Let's review River's lab results to figure out what may be wrong:

Test
    

River’s Results

Blood Tests
    

CK Very High

Creatine High

Calcium Low

Vitamin D Normal

Urine
    

Myoglobin Present

Low Urine Output

Step 1

You perform additional research to interpret these results while River is being treated.
1a) What are CK, Creatine, and Myoglobin?

CK (Creatine Kinase): An enzyme found in skeletal muscle, heart muscle, and brain.

1b) What are the functions of those molecules?

• CK (Creatine Kinase):l;.

• Myoglobin acts as an oxygen buffer, facilitates oxygen diffusion, and may catalyze reactions

1c) What condition does River have?

CK Very high resulting  possible muscle damage .

Creatine High-Elevated CK and myoglobin suggest muscle injury, possibly due to rhabdomyolysis.

Calcium Low

1d) How do the results relate to that condition?

 Myoglobin is a protein released from damaged muscle cells, and its presence may contribute to kidney dysfunction, leading to reduced urine production .

Please answer the above questions and submit your responses here. Make sure to label your responses as 1a), 1b), etc. Please keep your answers to ONE SENTENCE per question to describe what may be going on!

When Ca2+ binds to troponin and causes tropomyosin to shift?

Troponin C - an overview | ScienceDirect Topics

(a) In the absence of Ca2+, tropomyosin prevents the binding of myosin heads to actin. 

(b) When the [Ca2+] rises, Ca2+ binds to a subunit of troponin, which causes the tropomyosin to shift slightly into the groove of the actin filament. 

The shift in position of tropomyosin allows the myosin heads to bind to actin.

myosin

 

What kind of filament is myosin?

Introduction. Myosin filaments (also called thick filaments) are key components of muscle and non-muscle cells. In striated muscle, they overlap with thin (actin-containing) filaments in an orderly array, making a repeating pattern of sarcomeres, the basic units of contraction [1] (Figure 1a).

 Myosin filaments consist of myosin molecules, each having a tail of length 1500 Å and two elongated globular myosin heads, each with a dimension of 150 Å (Figure 3a). Myosin molecules comprise two heavy chains and four light chains.

Tropomyosin

 Tropomyosin is the prototypical two-chained, α-helical coiled coil protein that associates end-to-end and binds to both sides of the actin filament. Each tropomyosin molecule spans four to seven actin monomers in the filament, depending on the size of the tropomyosin.

 Is tropomyosin a thick or thin filament?
The thin filaments contain actin, tropomyosin, troponins C, I, and T and nebulin. 

The thick filaments are composed of myosin with the globular heads forming cross-bridges with thin filaments.Jul 16, 2008

Troponin

 Troponin I is part of a heteromeric thin filament regulatory complex that governs skeletal and cardiac muscle contraction. Troponin I is composed of three subunits: troponin I (TnI), troponin T (TnT), and troponin C (TnC), and each of these components plays a different functional role.

Muscle Contraction - Cross Bridge Cycle, Animation.

Sliding Filament Theory Of Muscle Contraction Explained

Difference between Troponin and Tropomyosin

 Out of the three, cardiac and skeletal muscles are composed of thin and thick filaments called sarcomere that enable muscle contraction. 

Troponin and tropomyosin are two proteins that are present on the thin filaments of the muscle cells and help in the contraction of muscles.

https://byjus.com/biology/difference-between-troponin-and-tropomyosin/#:~:text=Out%20of%20the%20three%2C%20cardiac,in%20the%20contraction%20of%20muscles.

Is tropomyosin a thick filament?

The thick filaments are made up of myosin while the thin filament is made up of three proteins actin, troponin, and tropomyosin.Jan 9, 2020

The thick filaments of muscle consist of several hundred myosin molecules, associated in a parallel staggered array by interactions between their tails (Figure 11.23).

 The globular heads of myosin bind actin, forming cross-bridges between the thick and thin filaments.

Week 10 - Muscle Contraction: Explain 2

 Week 10 - Muscle Contraction: Explain 2

So far, we know that muscle stimulation is activated by a series of electrical nerve impulses sent from the brain to our muscles. As an action potential arrives at the neuromuscular junction within a muscle cell, acetylcholine (ACh) is released and causes actin and myosin to change shape. The interactions between ACh, calcium, actin, and myosin is what causes muscles to mechanically contract. This is referred to as excitation-contraction coupling. But how does calcium specifically aid in this process though? Please review the diagram below and see if you can connect the dots from last week to this week.

There is a lot going on at the cellular and molecular level for muscles to contract! Please re-review the excitation-contraction couplingLinks to an external site., specifically the section related to Figure 10.8 (left image below), of your textbook that you learned last week. Relate your understanding of the excitation process of muscle contraction you studied last week to the next step in the contraction process between actin and myosin within sarcomeres (image to the right below).

To further strengthen your understanding, please review these two videos: 

Sliding Filament TheoryLinks to an external site.

Cross-bridge cycleLinks to an external site.

Week 10 - Muscle Contraction Review: Explain 1

 Week 10 - Muscle Contraction Review: Explain 1

From Muscle Excitation to Contraction: A Review

Please review the following information to help us remember how muscle cells generate contraction:

A motor unit is a single motor neuron comprised of an “upper-motor neuron” and “lower-motor neuron”. When your brain decides to move a muscle 

• (1), “upper motor neurons” from your motor cortex send a message down your spinal cord
• (2), where they synapse with "lower motor neurons"
• (3). These motor neurons then synapse with muscle fibers 
• (4), and releaser ACh across the neuromuscular junction 
• (5). Each muscle fiber contains myofibrils. Each myofibril within a muscle fiber contains sarcomeres, comprised of actin and myosin contractile proteins. 
• (6a), that allow for contraction.
• (6b), via myosin/actin chains sliding across each other.
• (6c). This is the final step in the contraction cycle that causes muscles to physically shorten and contract.

1. But what exactly happens after ACh is released from the neuromuscular junction that allows actin and myosin to pull on each other?
2.  Does it require energy? If so, where does that energy come from? Let's explore a bit more!

Week 10 - Muscle Contraction: Engage/Explore

 Based on what you have been learning about muscles so far, what specific events are taking place at the cellular and molecular level of actin and myosin that allow you to contract muscles during these workouts?   

Please try to write at least 3 sentences to share what mechanisms are taking place to allow muscle movement and muscle building.  If you are uncertain, that's completely OK!  No research is necessary now.  This is just a chance to explore your existing ideas.

submission

1. During strength training, such as CrossFit workouts, muscle fibers experience microscopic damage due to the intense contractions.
2.  The body activates satellite cells, which fuse with existing muscle fibers.
3. These fused cells contribute additional nuclei to the muscle fiber, enhancing its capacity for protein synthesis.
4. The increased protein synthesis leads to muscle hypertrophy, where the muscle fibers grow thicker and stronger.

Copilot Chat GPT

Certainly! Let’s delve into the fascinating world of muscle contraction and building. 🏋️‍♂️

Muscle Contraction Mechanism:

At the cellular level, muscle contraction primarily involves the interaction between two key proteins: actin and myosin.

When you perform a movement like a push-up or squat, nerve impulses from your brain travel to the muscle fibers.

These impulses trigger the release of calcium ions within the muscle cell, which bind to troponin (a regulatory protein) and cause a conformational change in tropomyosin (another regulatory protein).

This conformational change exposes the binding sites on the actin filaments.

Myosin heads (part of thick myosin filaments) then attach to these exposed binding sites on actin, forming cross-bridges.

ATP (adenosine triphosphate) provides energy for myosin heads to pull the actin filaments toward the center of the sarcomere (the basic contractile unit of muscle).

This sliding of actin and myosin filaments results in muscle contraction.

Muscle Building Mechanism (Hypertrophy):

During strength training, such as CrossFit workouts, muscle fibers experience microscopic damage due to the intense contractions.

In response, the body activates satellite cells, which fuse with existing muscle fibers.

These fused cells contribute additional nuclei to the muscle fiber, enhancing its capacity for protein synthesis.

The increased protein synthesis leads to muscle hypertrophy, where the muscle fibers grow thicker and stronger.

Key factors for muscle growth include protein intake, adequate rest, and progressive overload (gradually increasing resistance during workouts).

Energy Systems for Muscle Activity:

Muscles rely on different energy systems during exercise:

Phosphagen System: Provides rapid energy for short bursts of intense activity (e.g., sprinting, heavy lifting). Creatine phosphate stores are rapidly broken down to regenerate ATP.

Glycolysis: Breaks down glucose to produce ATP. It’s essential for moderate-intensity activities lasting several minutes.

Oxidative Phosphorylation: Utilizes oxygen to generate ATP from stored carbohydrates and fats. It’s crucial for endurance activities (e.g., long-distance running).

Remember, these processes occur simultaneously, allowing you to perform those challenging CrossFit workouts and build stronger muscles! 💪🔥12

Week 10 - Introduction & Goals Revisiting Muscle Stimulation

 Last week, we learned about muscle stimulation and the neuromuscular junction. We also learned how multiple consecutive stimuli over the neuromuscular junction activate certain motor units and shorten muscles to cause a contraction (refer to your textbook Links to an external site. for a review or here for a modular review)

This Week's Goals

The fact that our muscles can adapt to stimuli that allow us to dance, shake, workout, run, and play is phenomenal! If we didn’t have this mechanism, we’d never be able to move our bodies or lift any amount of weight. But what exactly is happening at a cellular level that causes our muscles to power contractions when we make efforts to move our bodies? This week, we are going to take muscle stimulation one step further by digging deeper into the role of energy and contractile proteins (actin and myosin) that mechanically aid in muscle contraction.

Woman weightlifting  

More specifically, we will seek to...

Explore the mechanisms involved in sliding filament model, the cross-bridge cycle, and ATP

Apply muscle fatigue to homeostatic perturbations involved in exercise overload