MEMBRANE PROTEINS - Types and Functions

Cell membrane

 The cell membrane is an extremely pliable structure  

composed primarily of back-to-back phospholipids (a “bilayer”). 

Cholesterol is also present, which contributes to the fluidity of the membrane, 

There are various proteins embedded within the membrane that have a variety of functions.

A single phospholipid molecule has a phosphate group on one end, called the “head,”which have negativity charge making head polar and hydrophilic or water loving.

Hydrophilic attract on water on both extracellular and intracellular enviroment.

Two side-by-side chains of fatty acids that make up the lipid tails.

 The lipid tails, on the other hand, are uncharged, or nonpolar, and are hydrophobic—or “water fearing.” 

A hydrophobic molecule (or region of a molecule) repels and is repelled by water.

 Some lipid tails consist of saturated fatty acids and some contain unsaturated fatty acids. 

This combination adds to the fluidity of the tails that are constantly in motion.

Phospholipids are thus amphipathic molecules.

 An amphipathic molecule is one that contains both a hydrophilic and a hydrophobic region. 

In fact, soap works to remove oil and grease stains because it has amphipathic properties. 

The hydrophilic portion can dissolve in water while the hydrophobic portion can trap grease in micelles that then can be washed away.

Application Question 14- exercise related with ATP and muscle stimulation

 
Application Question 14

    Due Mar 10 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.
Let's return to our scenario...

DumbellsPretend you have a friend who has recently gotten very excited about fitness and exercise. Now all she wants to talk about is what’s happening in her body during workouts! She’s started a new weight lifting program for her arms where she cycles quickly through various dumbbell exercises for a few minutes before resting and repeating later. She asks you to help her understand what’s happening in her muscle cells during and after those workouts.

Briefly explain (just a sentence or two for each point) how...

    Her muscles generate energy (ATP) to do this work?
    Her nervous system coordinates the stimulation/action potentials to her muscle cells?
    Her muscle cells will change over time as a result of her workouts?

Mostly Complete (10 pts): Address each of the three topics above with information about how muscles change during exercise. For #1, more than one energy harnessing method should be addressed, since the length of the exercise would require at least a couple ATP generation strategies. See the three pages immediately before this question for information about what to share for each of these three topics!

               I would explained my friend that during weight lifting,her muscles primarily produce energy (in the form of ATP) through aerobic respiration, which involves using oxygen to break down glucose and fuel muscle contractions.When her muscles contract, ATP molecules had to broken down to release energy.The frequency and intensity of these signals determine the force and duration of muscle contractions.

(1)  For short bursts of intense activity like weight lifting , her muscles rely on stored creatine phosphate (CP) to rapidly regenerate ATP.

(2)  For moderate-intensity exercise, glucose breakdown via glycolysis generates ATP.

(3) For longer activity oxygen is used to break down glucose into ATP molecules, providing sustained energy

            When lifting weights, the nervous system coordinates the firing of motor neurons, which stimulate muscle fibers to contract.Initially, muscle contractions are often partial and not strong enough to fully shorten the muscle cell.To achieve full muscle cell shortening and sustained contraction, the muscle cell must receive multiple signals in succession from the neuron.

       During workouts, the interaction between actin and myosin generates force in the muscle. Increasing the amount of actin and myosin results in greater force production and thicker, more defined muscles when lifting heavier weights.

         Consistent work out perform training, muscle fibers increase in size due to increased protein synthesis and the addition of contractile proteins actin and myosin. Aerobic exercise promotes mitochondrial growth within muscle cells. More mitochondria mean better ATP production through aerobic respiration.

Application Question 13 -Black Widow Spider Latrotoxin

 
Application Question 13

    Due Mar 10 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Look back over the responses from your classmates in the preceding discussion.  If you are satisfied with your original response to this question, simply copy and paste that response here!  If you wish to edit your original response based on what you saw in the discussion, make those changes before submitting.

Black Widow SpiderLatrotoxin is a compound produced by spiders in the genus Latrodectus (such as black widow spiders). Latrotoxin creates tiny holes in cell membranes at axon terminals that allow small hydrophilic particles to pass through the membrane.  Consider the above information and what we have learned thus far about activities in the neuromuscular junction.

What impacts would latrotoxin have on your muscles?

Discuss ACh, sodium, and calcium in your explanation.

Mostly Complete (10 pts): Muscles will be overstimulated/constantly contracting when exposed to venom.  Note that calcium would get into the axon terminal through the tiny holes and trace chain of events after that, including ACh and sodium.  View this video if you wish to review the steps that occur after calcium entry. Focus especially on the specific locations of ACh, calcium, and sodium and the order of the steps.

Partially Complete (6 pts): Answer is partially on track but incorrectly identifies the roles of either ACh, sodium, or calcium.

      Base on my understanding the sodium ions play a important role in muscle cell depolarization. Calcium ions are essential for muscle contraction. During normal muscle contraction, sodium channels open, allowing sodium ions to flow into the muscle cell.
           (1)   Latrotoxin effects affect cell membrane which sodium and calcium currents depolarize the membrane that allow influx of sodium and calcium ions .Binding to neuronal receptors disrupt normal neuromuscular junction function.

           (2)  Sodium ions play a critical role in muscle cell depolarization, when increase sodium ions into muscle cells triggers the release of calcium ions.

           (3)   Increase calcium ion [Ca2+] ion resulting in increase release ACH.  

           (4)   Excessive release of acetylcholine (ACH) at the neuromuscular junction,   resulting in increase muscle contraction of skeletal muscle and cardiac muscle.   Latroxin caused prolonged muscle contractions, spasms , muscle pain or  muscle damage.

Application Question 12 - Luis growth and height

 
Application Question 12

    Due Mar 3 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Look back over the responses from your classmates in the preceding discussion.  If you are satisfied with your original response to this question, simply copy and paste that response here!  If you see something in classmates' responses you wish to incorporate, add that information in before submitting.

One day your friend, Luís, who has always been somewhat short, comes up to you and says, “Okay, you A&P expert, I have a question for you! I exercise lots, eat calcium rich foods, and take vitamin D supplements, but I never get taller! Clearly my bones can grow, since I had a little growth spurt in high school, but I’ve been pretty much the same height ever since then. What was going on with my bones back then that isn’t happening now and why?” You sigh and pull out your A&P book to try to explain.

How do you respond to Luís?

Use the words “chondrocyte,” “osteoblast,” and “estrogen” in your explanation.

Mostly Complete (10 pts): Make appropriate use of the terms chondrocyte, osteoblast, and estrogen to describe activities in epiphyseal growth before and after puberty.  Recall that chondrocytes in the epiphyseal plate reproduce rapidly during puberty stacking on top of one another and lengthening long bones with new cartilage.  That cartilage is then calcified by osteoblasts so the bones are longer and the person is taller.  What happens toward the end of puberty and why?

Partially Complete (6 pts): Missing an accurate description of changes in epiphyseal growth during/after puberty including the roles of chondrocytes, osteoblasts, or estrogen.

   I will explain to Luis that

(1) chondrocytes are specialized cells found in the growth plates of our bones.

(2) Before puberty, chondrocytes divide and contribute to bone lengthening.

(3) The estrogen hormone released during puberty that triggered shortens the life of chondrocytes, leading to the cessation of bone elongation.

(4) At this stage, osteoblasts take over, binding calcium phosphate to harden the bone. Osteoblasts work hard to create new bone tissue, which lengthens  long bones and contributing to our height. Luis's bones settled into their final dimensions, and that’s why he hasn’t experienced significant height changes.As a result, Luis 's height stops at puberty, and so that Luis will no longer grow taller at this point.

Application Question 11 Vitamin D and clacium relating with osteoporosis

 
Application Question 11

    Due Feb 25 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Look back over the responses from your classmates in the preceding discussion.  If you are satisfied with your original response to this question, simply copy and paste that response here!  If you see something in classmates' responses you wish to incorporate, add that information in before submitting.

Pretend you overhear a conversation about skeletal health while on the bus. A woman is saying, “You wouldn’t believe this new doctor I’m seeing! I had all my blood tests done and they all came back great, except for low on vitamin D. And what does the doctor do? She tells me I should get a bone checkup for osteoporosis! Now you know I eat lots of food with calcium in it, and get this, my calcium blood levels are normal! What kind of doctor thinks you can get osteoporosis when your calcium levels are perfectly fine? I’m not getting that silly bone checkup.”

What would you be thinking during this conversation? If you were this woman’s doctor, how would you explain the recommendation to get a bone density test?

Mostly Complete (10 pts): Discuss the main point, which is that the only reason she has normal blood calcium is that her body is taking calcium from her bones to keep blood levels normal. Delve into the cellular/chemical aspect of this situation, including a reference to the involvement of important cells/chemicals in this feedback loop (i.e., the PTH/calcium feedback loop/vitamin D).

       According to the conversating the women stating that low level of vitamin D even though her  blood calcium is normal her doctor want her to do checkup for osteoporosis .  Vitamin D levels are tightly regulated by the body to maintain homeostasis. Vitamin D is essential for calcium absorption from the intestines. Low level of vitamin D resulting impaired calcium absorption. When blood calcium levels drop  the parathyroid glands release PTH. PTH/calcium feedback loop and vitamin D work together to maintain calcium homeostasis in the body. When blood calcium drops, PTH stimulates osteoclasts (bone-resorbing cells) to break down bone tissue, releasing calcium into the bloodstream. Therefore, a bone density test need to be recommended to check the bone density because osteoporosis can occur due to factors beyond on blood calcium levels.

Application 10 Indequated diagnosed for skin disease based on skin color

 
Application Question 10

    Due Feb 25 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Before we move on to some new topics, let's take a moment to reflect on our discussions in our last class meeting.  Feel free to look back at your notes or the lecture recording of the last meeting to refresh your memory!

Jenna Lester  Some of our discussions in our last lecture meeting focused on the following quote from one of Dr. Jenna Lester's papers.

"While fair-skinned people are at the highest risk for contracting skin cancer, the skin cancer mortality rate for African Americans is considerably higher."

On the surface, this might seem like a self-contradictory statement, but we learned this is just one of many examples of a health disparity related to the skin.  Describe at least one data point or statistic from one of the papers

Links to an external site. we read and explain what that data point or statistic tells us about how skin health disparities can come about.

Mostly Complete (10 pts): All of the papers we read discussed one of the causes (but by no means the only cause) of skin health disparities: the fact that skin of color is largely absent when looking at important sources for medical information.  In your answer, you should mention at least one finding or statistic from at least one of the papers to support the idea that skin of color is underrepresented in a medical or health source.  That underrepresentation could lead to less frequent diagnosis of diseases among persons of color or could lead to less relevant health recommendations to persons of color.

               According to the Skin Physiology Health Disparity Paper 2 in the study conducted among dermatologist ,47 percent of them expressed that their training was inadequate diagnosed for skin disease based on skin of color. This finding indicating that significant gap and underscore in medical education and it needs to improve training and awareness. The healthcare disparity related to skin of color is a critical issue that need focus on inadequate matters and need to take some action in order to improve the diagnosis and treatment plan. Lack of representation in medical education and clinical observation caused disparities in dermatological care such as misdiagnosis or delay diagnosis , delay treatment could affect the  outcome of patient health condition. Dermatologists must actively work toward bridging this gap by enhancing our understanding of skin diseases across diverse populations and advocating for equitable care for all patients.

Application 9 - Aging relation over Keratinocytes Fibroblasts Collagen/Elastin Lipids

 
Application Question 9

    Due Feb 18 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Changes in the skin often serve as the most immediately noticeable signs of aging for humans. Hopefully we are now using an A&P mindset when thinking about aging!

To demonstrate that A&P mindset, discuss how each of the following cells or molecules relate to a symptom of aging in the skin:

    Keratinocytes
    Fibroblasts
    Collagen/Elastin
    Lipids

Feel free to open up another window so you can refer back to earlier discussion boards or other pages in this module!  You can also refer to the complete set of article excerpts

Download complete set of article excerpts on this topic.

Mostly Complete (10 pts): Response should mention 1. a symptom of aging related to each of the cells/molecules above as well as 2. some brief note about how the cell/molecule relates to that symptom (e.g., "collagen and elastin relate to reduced skin thickness, because there is less of those proteins in the dermis with age making it thinner").

Partially Complete (6 pts): One or more cell/molecule from list not discussed or discussions do not adequately connect the cells/molecules with their symptom (e.g., only saying "collagen and elastin relate to reduced skin thickness")

 

Application Question 8 - Skin Problem

 
Application Question 8

    Due Feb 18 by 11:59pm Points 10 Submitting a file upload Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Before we move on to some new topics about the skin, let's take a moment to reflect on our discussions in our last class meeting.  Feel free to look back at your notes or the Zoom recording of the last meeting to refresh your memory!

Some sort of disease, injury, or infection has afflicted someone’s skin! Your job is to figure out what’s going on and show your evidence for conclusion.

Clues
Keratinocyte: Desmosomes disrupted. Sending cytokines to attract WBCs. Keratinocyte Stem Cell: Dividing more rapidly to replace cells. Making complement proteins to seek out microbes. Melanocyte: Momentarily detected increased UV radiation in the skin but then the stimulus went away. Langerhans Cell: Identified numerous targets and am eliminating them. Fibroblast: There’s a need for a small amount of new dermal protein fibers. Dermal Dendritic Cell: No unusual activity requiring my services. Merkel Cell: Sensed a sudden increase in pressure in one area of the skin. Lamellated Corpuscle: No signals out of the ordinary.

Using a spare piece of paper or an index card or post it, create a diagram of the skin based on the clues. All 8 cell types and information from the clues should be represented. Show or label your idea of what the skin problem is!

Take a picture of your diagram and upload it here.

Don't spend too much time on the artistry!  Remember that we started this together during Zoom and I showed some ways to do this with simple lines and abbreviations!

Note: This is intended to be done on paper, not on a computer. If you're using the Canvas phone/table app, you can take a picture of your diagram with your device and upload it directly from there within the Canvas app.  If you're not using the app, you can send the picture to yourself by email and then upload it here on your computer.

Mostly Complete (10 pts): Diagram shows all 8 cell types in their appropriate positions/layers.  To clarify the locations of cells, check the location information in the clues in this sorting activity
Links to an external site..  You might compare those location descriptions to a diagram of the skin's layers, such as this one

Links to an external site..  Diagram shows or mentions a reasonable injury, disease, or infection based on the evidence in the clues.

Partially Complete (6 pts): One or more of the 8 cell types is not shown or appears in the wrong location in diagram.  Or information on a skin problem related to clues is absent.

Application Question 7-Abestos

 

Application Question 7

• Due Feb 11 by 11:59pm
• Points 10
• Submitting a text entry box
• Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Now that you have had an opportunity to reflect on this question and get some ideas from colleagues, take this opportunity to more formally record a response...

Pretend you’re called as an expert witness in a court case about asbestos. The person suing (the plaintiff) worked in an asbestos mine in Canada and says it is now hard for him to breathe due to exposure to asbestos. As an expert witness, use your A&P knowledge to describe to the judge how the asbestos could relate to the plaintiff's difficulties.  You should...

Describe two different membranes that you think are likely impacted, including where those membranes are located, what specific tissue types they're are made of, and how you think the presence of spiky asbestos within those membranes could inhibit their normal functions.

You might want to open another window to go to earlier pages in this module and remind yourself of where asbestos can go to in the body.

Mostly Complete (10 pts): Describe mucous membranes and serous membranes in terms of their locations and cell/tissue composition.  Please be specific regarding tissue types (e.g., what type of epithelial or what type of connective tissue)!  Make a prediction (at least a guess!) at how the functions of those membranes might be impeded if stiff, spiky asbestos was embedded within them.

Partially Complete (6 pts): Mucous and serous membranes identified, but one of above details missing.

 

                 When asbestos fibers are inhaled, they can reach the alveoli, a tiny air sac of the lungs. Asbestos fibers are not only penetrate the pleura but also reach the alveoli. The pleura consists of a serous membrane, composed of a layer of simple squamous cells called mesothelium which is supported by connective tissue. The pleura located double-layered membrane in the thoracic cavity covers the lungs called parietal pleura and visceral pleura consist of a serous membrane.The pleura acts as protective barrier, reducing friction during lung movement and facilitating efficient breathing.  

                When inhale asbestos fibers, that spiky asbestos fibers embedded within mucous membranes and serous membranes. Asbestos fibers stuck on the alveoli  cause chronic inflammation and damage to the alveolar cells and endothelial cells.Asbestos fibers can lead to fibrosis and scarring of the epithelial lining.Fibrosis develops within  squamous epithelial cells that form the alveolar walls .Asbestos fibers on cells affect blood flow within the alveolar  membrane. Chronic inflammation leading to thickening of the pleura that caused reduce the pleura’s elasticity and impair lung expansion follow by impaired gas diffusion, reducing the efficiency of oxygen uptake and carbon dioxide removal so that the patient presenting with breathing difficultly progressive shortness of breath.

Application Question 6- Acne

 
Application Question 6

    Due Feb 11 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Now that you have had an opportunity to reflect on this question and get some ideas from colleagues, take this opportunity to more formally record a response.

acnePretend a friend tells you, “I can’t believe I still get pimples even though I’m not a kid anymore! My doctor keeps telling me not to poke or scratch at my pimples, but I always want to just get them off!”

Use an A&P perspective to explain why your friend’s doctor would say to not poke or scratch pimples. Use the words “myofibroblasts,”  “collagen,” and "migrate" in your answer.

Feel free to refer to the journal article excerpt

Download journal article excerpt about "wound healing vs. fibrosis," the last segment of the Zoom recording from class.

Mostly Complete (10 pts): Include myofibroblasts, collagen, and migrate in your response. In particular discuss the special characteristics of myofibroblasts and how this situation could lead to excess collagen production and that would form a scar.  Refer to the article linked above and especially some of the info at the end about how/why fibrosis occurs. There are some specific roles for collagen, especially, that might occur if this person is constantly irritating the skin.

Partially Complete (6 pts): Discuss relevant information related to the three key terms, but answer does not connect excess collagen production to the scenario/fibrosis.

         When you scratch a wound, it disrupts the delicate balance of skin cells and collagen fibers involved in the repair process. While wound healing is essential, chronic inflammation and excessive repair can trigger the accumulation of extracellular matrix (ECM). Myofibroblasts, responding to chemical signals, migrate to the wounded area and produce collagen and other extracellular matrix proteins. Although myofibroblasts play a role in wound contraction, their persistent presence can lead to excessive scar tissue formation, known as fibrosis. This occurs when the synthesis of new collagen by myofibroblasts exceeds the rate at which it is degraded, resulting in an overall increase in collagen content over time.Continuously scratching the healing process disrupts the formation of smooth collagen, leading to irregular scar tissue and permanent scarring. Therefore, doctors advise against poking or scratching pimples, as it not only worsens inflammation but also contributes to fibrosis or scarring.

Application Question 5-identical twin

 
Application Question 5

    Due Feb 4 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Now that you've gotten to check your ideas by seeing some of your classmates' responses, let's take an opportunity to record your final thoughts for now.  Your response might be the same or different from in the previous discussion, but please re-write (or paste in) your complete answer.

Screen Shot 2018-10-04 at 11.49.08 AM.png

You run into your old friend, Aaron, who tells you that (strange as it sounds) he and his identical twin brother Jared got married to identical twin sisters! He says it’s going to be really exciting, because both couples just had baby girls, so his and Jared’s kids will also be identical twins!

Using your understanding of meiosis (e.g., including crossing over/recombination & independent assortment), what do you say to Aaron in response?

(Hint: since the important processes here act on pairs of chromosomes, it can be helpful to use "within pairs" or "between pairs" or "from each pair" frequently in your responses!)

 

Mostly Complete (10 pts): Describe issues related to both independent assortment and crossing over/recombination.  Both of those processes mean it's extremely unlikely Aaron and Jared will produce identical sperm, much less that those sperm will fertilize identical eggs from their partners.  Make sure response is clear that those processes occur between each pair of chromosomes (not between chromosomes from different pairs) in each individual's body.  The Week 5 lecture recording includes a discussion/clarification of this!

Partially Complete (6 pts): Explain just one of the two concepts described above.  Also note that responses will be marked only partially complete if they indicate that crossing over happens between mother/father or male/female or egg/sperm chromosomes.  Crossing over happens before fertilization within a single individual's body between that person's chromosome pairs.  Crossing over is not expected to happen between egg and sperm chromosomes after fertilization.

           Jared  and Aaron 's DNA that is passed along to their baby will include new combinations of codes due to crossing over. Crossing creates the new combinations of genetic material on chromosomes that is not possible  for these twins to create identical twin babies.  Cross over,  created their reproductive cells are made in independent assortment, there are numerous different combinations using the equation of 2 to the power of how many pairs of chromosomes they have (23), which makes more than around 8 million combinations.

        Meiosis is a division that a single cell divides twice and produces four daughter cells which  contain half the amount of genetic material from parents called sex cells (gametes).Meiosis produces cells that are genetically unique from the parents and contain only half DNA from parents.  Although the baby can inherit some traits from the parents their baby can not become identity twins liked Jared  and Aaron.


 

Application Question 4 - Disscussion about Cancer

 
Application Question 4

    Due Jan 28 by 11:59pm Points 10 Submitting a text entry box Available until Mar 26 at 1pm

This assignment was locked Mar 26 at 1pm.

Now that you've had a chance to clarify your ideas by reviewing some of your colleagues' responses, take a moment to share some of your final thoughts on the prompt below.

Prompt:

DNA Your friend tells you she recently had genetic testing done, and her doctor said she “inherited a single mutation in a gene that is connected to breast cancer.”

Your friend is unsure what this means and is worried she will definitely get breast cancer later in life.

We’ve now discussed many reasons why your friend would not be 100% guaranteed to get cancer - particularly aggressive cancer - based on just 1 mutation!

Explain at least three specific, cell biology reasons why.

Mostly Complete (10 pts): 

• Discuss the roles of at least three of the following in cancer development: 
• Cyclins
• Oncogenes, 
• Tumor Suppressors,
•  Metastasis, 
• Angiogenesis, 
• Desmosomes/
• Adherens Junctions, 
• Cell Specialization, etc.

Partially Complete (6 pts): Discuss only one or two of the factors above, or discuss three things but with incomplete or incorrect descriptions of their roles.

 

Based on just one genetic mutation my friend may not get cancer.Oncogene is a mutated gene that has the potential to cause cancer. The normal healthy adult their genetic and cellular mechanisms can prevent the growth and spread of the cancer mutation.

Cyclins control the progression of the cell cycle by activating particular enzymes one kinase in humans activates the proteins that carry out DNA replication.In healthy adult the DNA damage everyday which called mismatch ,but  DNA fixed by itself.The error form different form sometime nucleotide match the correct way. Each nucleotide contain base each DNA during replication the enzyme DNA polymerase help to bring the right partner pair with every base. The enzyme catches the mismatch and repair it right away which called mismatch repair.

 The healthy adult body the DNA mismatch repair by it self. Sometime lots of different molecules could cause chemical changes to nucleotide which was the trigger such as exposure from our environment chemicals , substances , UV light, contain chemical compound in smokes that caused DNA damage.  But our body have specific enzyme to reverse or correct the damage. Our body cell also has more general repair pathways . Just one base is damaged it can usually fixed by a process called base excision repair.  

If  double strand DNA is not damage she may not get cancer.   Cancer needs a blood supply to grow or spread  is called angiogenesis. Metastasis is spreading the cancer to other part of the body.

Application Question 3 -Imatinib drug

 This assignment was locked Mar 26 at 1pm.

Now that you've had a chance to think about this and refine your ideas by seeing some colleagues' responses, let's take a chance to record your final (for now) thoughts on this prompt.  I highly encourage you to review your colleagues' responses to in the past discussion before submitting your answer here!

• Imatinib is a drug that is used to treat leukemia.
•   It dissolves easily in water and has been found to build to very high concentrations in diseased cells.

Recall that we discussed four ways materials move across membranes:

1) simple diffusion
2) facilitated diffusion
3) active transport
4) endo/exocytosis.

Refer to this yes/no decision tree

Download yes/no decision tree for determining modes of transportation for chemicals.

Given the information above, you should be able to eliminate some of those 4 methods as possibilities for imatinib.

Which of the four transport methods can you eliminate in this case and how do you know imatinib is not using those transport methods to get through cell membranes?

In case it helps, the slides for this topic can be found here and there's also a video

Links to an external site. about membrane transport.

Mostly Complete (10 pts): Note that because this chemical moves to higher concentrations (goes against concentration gradient) that means it cannot be moving by any form of diffusion.  So we can eliminate BOTH of our forms of diffusion.  The drug is hydrophilic, so that's yet another reason it cannot move by simple diffusion, which is reserved for hydrophobic chemicals.

Click here to see information on revising application questions for additional points

Imatinib drug is easy to dissolved in water , so that it cannot be simple diffusion .  It is not facilitate diffusion because  Imatinib drug build up highly concentration. The molecule is large it cannot across lipid bilayer so that it  need assistant to eliminate  by endo/exocytosis.

 

Application Question 2- Body temperature homeostasis

              When the person was infected  corona virus the patient having the symptom of high temperature. During a fever, the body is maintaining a temperature of 101°F, it is actually operating within a negative feedback loop.The hypothalamus, a part of the brain, acts as the body’s thermostat and detects the elevated temperature. Chemical signals are released to the brain, alerting it to the increased temperature.In response, the hypothalamus triggers various physiological mechanisms to reduce the body temperature and restore it to the normal range.These efforts include sweating and vasodilation (expansion of blood vessels), which aim to bring the temperature back to normal. The normal body temperature typically hovers around 98.6°F (37.0°C). During a fever, a new set point temporarily shifts upward (from 98.6°F to 101°F) due to infection.The negative feedback loop then works to bring the elevated temperature back toward this new set point. Maintaining a temperature of 101°F during a fever example of rheostasis, where the body adjusts its set point to respond to specific conditions.The negative feedback loop ensures that deviations from this adjusted set point are corrected, promoting overall health and stability.

 

Application Question 1- Homeostasis osteoporosis

    Our body maintains calcium by homeostasis. When we don’t consume enough calcium through our diet, the body compensates by adjusting calcium levels.A special gland parathyroid gland is the control center that  senses changes in blood calcium levels and responds accordingly. Low calcium (stimulus) triggers the (effector) parathyroid hormone release.Parathyroid hormone stimulates bone cells  to break down bone tissue this process is called resorption. As a result, calcium is released from the bones into the bloodstream.When blood calcium returns to normal, PTH secretion stopped.This is the example of Negative Feedback Loop.The system self-regulates to prevent extreme deviations from the set point.Ultimately, this helps prevent conditions of osteoporosis.

Biology Instructor Receives Teaching Award

 

Biology Instructor Receives Teaching Award

 

Biology instructor Jeff Schinske was recently selected as the 2018 recipient of the Outstanding Undergraduate Science Teaching Award (OUSTA) from the Society for College Science Teaching. Schinske is the first community college instructor to receive this prestigious award. 

The OUSTA recognizes the achievements of science teachers who have enhanced the profession through excellence, scholarship and service. Schinske will accept the award and present at the National Science Teachers Association conference in March. 

In his current position, Schinske co-coordinates Foothill's anatomy and physiology courses and serves as the lead biology curriculum reviewer for California's statewide articulation system, C-ID. His current research focuses on equity and inclusion in science classrooms, the underrepresentation of community colleges in biology education research, and STEM faculty development. 

Schinske has published numerous peer-reviewed articles on STEM teaching and learning, has served as PI or Co-PI on four NSF grants, was interviewed by Nature for an article on community college teaching, and recently appeared as a senior author on an article in the Proceedings of the National Academy of Sciences (PNAS) on measuring faculty teaching practices in STEM classes. He is frequently invited as a plenary speaker on issues of equity and diversity in STEM education and has facilitated discussions on the topic at institutions ranging from small community colleges to large universities. 

 

https://www.lifescied.org/doi/10.1187/cbe.16-01-0002 

 

Langerhans cells

 
Langerhans Cell
Kate Latham
By:
Kate Latham
Biologydictionary.net Editors. (2021, April 26). Langerhans Cell. Retrieved from https://biologydictionary.net/langerhans-cell/
Reviewed by: BD Editors
Last Updated: April 26, 2021

Langerhans cells are a type of immune cell found primarily in the epidermis that have important roles in the stimulation and suppression of the adaptive immune response. They are members of the dendritic cell family and function as antigen-presenting cells. When a Langerhans cell encounters a pathogen, it engulfs the infectious agent and breaks it down into protein fragments. Some of these fragments are displayed on the surface of the cell and presented to naïve T cells in the lymph nodes to stimulate an immune response.

 What is a Langerhans Cell?

Langerhans cells are a type of immune cell found in the skin (AKA the epidermis). Like all immune cells, Langerhans cells are formed in the bone marrow. Once released from the bone marrow, they circulate in the blood before migrating to the skin, where they guard the epidermis against infection from pathogens.

Langerhans cells are members of the dendritic cell family and function as antigen-presenting cells (APCs) in the skin. They capture any pathogens they find roaming the epidermis and display their antigens on their surface to stimulate other immune cells into action.
Where Are Langerhans Cells Found?

Langerhans cells are present in all layers of the epidermis and the respiratory, digestive, and urogenital tracts. When they encounter a pathogen, Langerhans cells migrate to the lymph nodes to present their antigens to naïve T cells and activate the adaptive immune response.

 Function of Langerhans Cells

Langerhans cells are members of the dendritic cell family. Their main role is to alert other components of the adaptive immune system to the presence of pathogens and other infectious agents on the skin.
Langerhans Cells as Antigen-Presenting Cells (APCs)

Langerhans cells are phagocytic cells, meaning they engulf other cells or particles. They are also antigen-presenting cells (APCs), and can display fragments of engulfed pathogens on their cell surface to stimulate an adaptive immune response.

When a Langerhans cell encounters a harmful pathogen in the skin, it ingests it and breaks it down into protein fragments. Some of these fragments are displayed on the surface of the Langerhans cells as part of the Major Histocompatibility Complex (MHC).

Next, the Langerhans cells migrate to the lymph nodes to present their antigens to naïve T cells. This activates the T cells to launch an immune response and stimulates them to find and destroy the invading pathogen.
Langerhans cells present antigens to naive T cells
Langerhans cells are antigen-presenting cells
Immune Suppression by Langerhans Cells

Langerhans cells play a role in stimulating the adaptive immune response against pathogens, but they are also known to suppress immune function. The skin is naturally populated by ‘friendly’ bacteria which, although ‘foreign’ to the body, are not known to cause disease. In the presence of non-pathogenic bacteria, the Langerhans cells coordinate immune tolerance, i.e., they prevent the immune system from responding. This prevents unnecessary and potentially harmful activation of the immune system.
Langerhans Cells Prevent Autoimmunity

Langerhans cells help to prevent autoimmunity (an immune response against healthy cells) by promoting immune tolerance.

Under ‘non-dangerous’ conditions (i.e., when there are no pathogenic agents present), Langerhans cells promote the activation and proliferation of T regulatory (Treg) cells in the skin. Treg cells secrete cytokines that promote immune tolerance and, in doing so, prevent unnecessary and potentially harmful immune activation.

In the presence of a pathogen, however, Langerhans cells promote the activation of effector T cells and limit the activation of Treg cells. They stimulate the effector cells (namely, helper and cytotoxic T cells) to launch an immune response against the foreign invader and clear infections from the skin.
Langerhans cells may stimulate either Treg or effector T cells
Langerhans cells stimulate Treg cells to promote immune tolerance
What is Langerhans Cell Histiocytosis (LCH)?

Langerhans Cell Histiocytosis (LHC) is a rare type of cancer in which abnormal Langerhans cells grow and multiply rapidly. This leads to a build-up of Langerhans cells in various regions of the body, including the skin, mouth, lymph nodes, thymus, eyes, endocrine system, central nervous system (CNS), liver, spleen, lungs, or bone marrow. The abnormal proliferation of Langerhans cells can cause tissue damage and lesions to form in affected body parts, and symptoms vary depending on which region of the body is affected.

In approximately 80% of cases, LCH affects the bones (typically the skull or the bones of the arms or legs). This causes pain and swelling and may lead to bone fracture. LHC is also known to frequently affect the skin, where it may cause rashes, bumps, and blisters that can be mild or severe. If the pituitary gland is affected, LHC may disrupt hormone production, which may lead to infertility or, in adolescents and children, delayed or absent puberty. LHC may also affect the thyroid, leading to the disruption of the patient’s normal skin and hair texture, body temperature, and behavior.

Melanocytes

 

Lamellated corpuscle

 The lamellar corpuscle is a type of large, ovoid, rapidly adapting, encapsulated nerve ending sensitive to pressure, touch, and vibration. The most complicated of the nerve endings, its core contains the nonmyelinated nerve terminal and its Schwann cells, surrounded by concentric layers of modified fibroblasts, in cross-section resembling a sliced onion. It is found in the skin and deeper tissues, particularly in the palms, soles, digits of hands and feet, joints, external genitalia, and breasts (Dorland, 2011).

application 8 revised

     I would explained my friend that during weight lifting,her muscles primarily produce energy (in the form of ATP) through aerobic respiration, which involves using oxygen to break down glucose and fuel muscle contractions.When her muscles contract, ATP molecules had to broken down to release energy.The frequency and intensity of these signals determine the force and duration of muscle contractions.

(1)  For short bursts of intense activity like weight lifting , her muscles rely on stored creatine phosphate (CP) to rapidly regenerate ATP.

(2)  For moderate-intensity exercise, glucose breakdown via glycolysis generates ATP. 

(3) For longer activity oxygen is used to break down glucose into ATP molecules, providing sustained energy

            When lifting weights, the nervous system coordinates the firing of motor neurons, which stimulate muscle fibers to contract.Initially, muscle contractions are often partial and not strong enough to fully shorten the muscle cell.To achieve full muscle cell shortening and sustained contraction, the muscle cell must receive multiple signals in succession from the neuron.

       During workouts, the interaction between actin and myosin generates force in the muscle. Increasing the amount of actin and myosin results in greater force production and thicker, more defined muscles when lifting heavier weights.

         Consistent work out perform training, muscle fibers increase in size due to increased protein synthesis and the addition of contractile proteins actin and myosin. Aerobic exercise promotes mitochondrial growth within muscle cells. More mitochondria mean better ATP production through aerobic respiration.

     

 

 

 1.During her weightlifting workout, her muscles generate energy (ATP) primarily through a process called aerobic respiration, where oxygen is used to break down glucose into ATP molecules, providing the necessary energy for muscle contraction. Additionally, muscles could use stored energy in the form of creatine phosphate (CP). Another way that uses energy stored within carbohydrates from the blood or from muscle cell reserves to generate ATP.

2.During her workout, her nervous system sends signals to her muscle cells through neurons, triggering action potentials that result in muscle contraction. The frequency and intensity of these signals are adjusted by her nervous system to match the demands of the exercise.

However, this contraction isn't usually strong enough to fully shorten the muscle cell and it's more like a partial contraction.

To fully shorten the muscle cell and keep it contracted, it needs to receive multiple signals, one after the other, from the neuron. The more signals it gets in a row, the more the muscle cell shortens, and the longer it stays contracted.

When she workout, the pulling of actin by myosin provides force in her muscle, therefore adding more actin and myosin will get more force. That will also make your muscles thicker and appear more muscle when she continues lifting heavier weights.
 

 1.During her weightlifting workout, her muscles generate energy (ATP) primarily through a process called aerobic respiration, where oxygen is used to break down glucose into ATP molecules, providing the necessary energy for muscle contraction. Additionally, muscles could use stored energy in the form of creatine phosphate (CP). Another way that uses energy stored within carbohydrates from the blood or from muscle cell reserves to generate ATP. 

2.During her workout, her nervous system sends signals to her muscle cells through neurons, triggering action potentials that result in muscle contraction. The frequency and intensity of these signals are adjusted by her nervous system to match the demands of the exercise.

However, this contraction isn't usually strong enough to fully shorten the muscle cell and it's more like a partial contraction.

To fully shorten the muscle cell and keep it contracted, it needs to receive multiple signals, one after the other, from the neuron. The more signals it gets in a row, the more the muscle cell shortens, and the longer it stays contracted.

When she workout, the pulling of actin by myosin provides force in her muscle, therefore adding more actin and myosin will get more force. That will also make your muscles thicker and appear more muscle when she continues lifting heavier weights.

   I would explained my friend that during weight lifting, muscle contraction requires energy, and when ATP is broken down

oxygen need to breakdown produce energy in the form ATP (adenosine triphosphate) to contract and perform work. 

 When the muscle cell is at rest, it uses some of its ATP to add a phosphate group to creatine, forming CP. When ATP levels drop during intense exercise, CP steps in. It’s rapidly broken down to generate more ATP, providing a burst of energy for about 8–10 seconds. Motor neurons transmit electrical signals from the brain , spinal cord to the muscle. When lifting weights, the nervous system coordinates the firing of motor neurons, which stimulate muscle fibers to contract.The frequency and intensity of these signals determine the force and duration of muscle contractions.Consistent work out perform training, muscle fibers increase in size due to increased protein synthesis and the addition of contractile proteins actin and myosin. Aerobic exercise promotes mitochondrial growth within muscle cells. More mitochondria mean better ATP production through aerobic respiration.

four forms of energy important in human functioning

 four forms of energy important in human functioning

Decompression sickness (DCS)

 Decompression sickness (DCS) is a condition in which gases dissolved in the blood or in other body tissues are no longer dissolved following a reduction in pressure on the body. This condition affects underwater divers who surface from a deep dive too quickly, and it can affect pilots flying at high altitudes in planes with unpressurized cabins. Divers often call this condition “the bends,” a reference to joint pain that is a symptom of DCS.

 In all cases, DCS is brought about by a reduction in barometric pressure. At high altitude, barometric pressure is much less than on Earth’s surface because pressure is produced by the weight of the column of air above the body pressing down on the body. The very great pressures on divers in deep water are likewise from the weight of a column of water pressing down on the body. For divers, DCS occurs at normal barometric pressure (at sea level), but it is brought on by the relatively rapid decrease of pressure as divers rise from the high pressure conditions of deep water to the now low, by comparison, pressure at sea level. Not surprisingly, diving in deep mountain lakes, where barometric pressure at the surface of the lake is less than that at sea level is more likely to result in DCS than diving in water at sea level.

 

 n DCS, gases dissolved in the blood (primarily nitrogen) come rapidly out of solution, forming bubbles in the blood and in other body tissues. This occurs because when pressure of a gas over a liquid is decreased, the amount of gas that can remain dissolved in the liquid also is decreased. It is air pressure that keeps your normal blood gases dissolved in the blood. When pressure is reduced, less gas remains dissolved. You have seen this in effect when you open a carbonated drink.

 Removing the seal of the bottle reduces the pressure of the gas over the liquid. This in turn causes bubbles as dissolved gases (in this case, carbon dioxide) come out of solution in the liquid.

The most common symptoms of DCS are pain in the joints, with headache and disturbances of vision occurring in 10 percent to 15 percent of cases. Left untreated, very severe DCS can result in death. Immediate treatment is with pure oxygen. The affected person is then moved into a hyperbaric chamber. A hyperbaric chamber is a reinforced, closed chamber that is pressurized to greater than atmospheric pressure. It treats DCS by repressurizing the body so that pressure can then be removed much more gradually. Because the hyperbaric chamber introduces oxygen to the body at high pressure, it increases the concentration of oxygen in the blood. This has the effect of replacing some of the nitrogen in the blood with oxygen, which is easier to tolerate out of solution.

The dynamic pressure of body fluids is also important to human survival. For example, blood pressure, which is the pressure exerted by blood as it flows within blood vessels, must be great enough to enable blood to reach all body tissues, and yet low enough to ensure that the delicate blood vessels can withstand the friction and force of the pulsating flow of pressurized blood.

 

 definitive of human life: organization, metabolism, responsiveness, movement, development, and reproduction.

Every cell in your body makes use of a chemical compound, adenosine triphosphate (ATP), to store and release energy.

 The cell stores energy in the synthesis (anabolism) of ATP, then moves the ATP molecules to the location where energy is needed to fuel cellular activities.

Then the ATP is broken down (catabolism) and a controlled amount of energy is released, which is used by the cell to perform a particular job.

Metabolic processes 

anabolic reactions- involve bulding require energy to proceed 

catabolic reaction- breakdown suger to release energy

ATP adenosene tri phosphate contain phosphate ion is release 

ADP cellular repiration 

Week 11 - Reflecting On Learning

 Recall that reflecting on what you have learned and how you learned those things is a critical process for strengthening synapses, and therefore strengthening memories.  Think broadly about your Bio 40A experiences, going all the way back to the first day of class and extending through the present.  Take plenty of time to reflect and consider...

1.     the coursework and Canvas assignments you completed
2.     our on-campus meetings
3.     your interactions with classmates and with me
4.     any new skills, strategies, attitudes, or mindsets you have developed
5.     relevant conversations you've had with friends and family
6.     any other official or unofficial experiences related to your participation in Bio 40A over the last 11 weeks!

As you reflect on the above, compose a 500 word or more reflection on the prompt...

    What from Bio 40A do you think you will remember and continue to use/practice/act on years from now?
    Why did you choose those things?
    How do you think you learned those things?

There are absolutely no right or wrong answers and nothing would please me more than to see a wide range of ideas from one student to the next!  You will receive credit based on...

    4 points - Writing at least 500 words (your word count will be displayed in the bottom right as you type)
    8 points - Providing details, examples, and a candid analysis of your experiences, personal progress, anticipated memories, and applications of what you've learned going forward

In this class]

• I realling like learning on case scanerio , it really helpful think out of the box which help me improve critical thinking.
• researching on the internet and discuss with the classmate .
• engage in meaningful discussions with classmates.
•  

Lab experiences 

in the past i was afraid the lab

not familier about using microscopes don't know how to adjust the magnifier .

I felt not enough to practice in lab 

I purchase small not expensive microsocope and practice 

 confident on using microscopes  

now i am enjoying using microscopes 

fell in love study in with science 

Overcoming the initial fear and unfamiliarity with microscopes, I took the initiative to practice and become confident in using them. Lab hand on assignment not only improved my skills but also sparked a love for science. Lab hands-on experience help me transform apprehension into enjoyment and passion for learning science. I love to continue to explore the microscopic world.

In my earlier years, I harbored a fear of science. Science classes used to make my heart race, especially when I started learning biological concepts in high school. When I started learning Biology 40A in college, I noticed that my fear of the subject had diminished compared to high school. Perhaps the teaching approach played a significant role in making science enjoyable for me. The teaching methods seemed to foster a newfound appreciation for learning science. Biology 40A covers human anatomy and physiology. It delves into the fascinating world of cells, tissues, organs, and systems within the human body. I enjoyed participation in both classroom and online activities. I find learning through case scenarios is truly beneficial. It encourages me to think outside the box and enhances critical thinking skills. In class activity research on specific scenarios and case study online, broadening my understanding. Engaging in meaningful discussions with classmates enriches my learning experience. Collaborating with peers provides diverse perspectives and fosters deeper understanding. Another thing is that regular assessments, quizzes, and feedback loops help me gauge my progress and identify areas for improvement.

Overcoming the initial fear with the lab because I was unfamiliar with using microscopes. I purchased a little microscope and diligently practiced, which help me not only boosted my confidence but also ignited a genuine love for science. Lab hand on assignment not only improved my skills but also sparked a love for science. Lab hands-on experience helps me transform apprehension into enjoyment and passion for learning science. I’m eagerly looking forward to delving deeper into the microscopic realm next semester as I explore Biology 40B, 40C, and the fascinating field of microbiology.
In the class of Biology 40A, I forged more than just scientific knowledge. I honed my analytical skills, navigated complex concepts, and discovered the art of inquiry. Beyond textbooks and lab reports, I unearthed the power of active engagement, self-reflection, and continuous feedback. These lessons, like seeds planted in fertile soil, will bear fruit throughout my academic and personal voyage. Armed with curiosity and resilience, I set sail—a lifelong learner charting uncharted waters