Saturday, March 9, 2024

application question 13 -Latrotoxin

 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.

 


             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.
          Latrotoxin effects affect cell membrane which sodium and calcium currents depolarize the membrane that allow influx of sodium and calcium ions .

  • Sodium ions play a critical role in muscle cell depolarization, when increase sodium ions into muscle cells triggers the release of calcium ions.
  • Increase calcium ion [Ca2+] ion resulting in increase release ACH.   Binding to Neuronal Receptors disrupt normal neuromuscular junction function.
  • Excessive release of acetylcholine (ACH) at the neuromuscular junction,   resulting in increase muscle contraction of skeletal muscle and cardiac muscle.  




Week 9 - Muscle Stimulation: Elaborate


Consider the prompt below.  Compose a reply and post that to the discussion.  You will be able to view classmates' responses to this same prompt after you submit.  There is no requirement to reply to a classmate's post!

Discussion Prompt:

Black Widow Spider Latrotoxin 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.

 

Latrotoxin effects affect cell membrane which sodium and calcium currents depolarize the membrane that allow influx of sodium and calcium ions .

Increase calcium ion [Ca2+] ion resulting in increase release ACH  . Excessive release of acetylcholine (ACH) at the neuromuscular junction,   resulting in increase muscle contraction of skeletal muscle and cardiac muscle.  

Botulinum toxins

 Botulinum toxins block nerve functions and can lead to respiratory and muscular paralysis.

 Human botulism may refer to foodborne botulism, infant botulism, wound botulism, and inhalation botulism or other types of intoxication.

 (Choice A) Botulinum toxin irreversibly blocks acetylcholine release from presynaptic membranes of neuromuscular junctions. 

After exposure to the toxin, patients may develop cranial nerve abnormalities (including ptosis and facial weakness), symmetric descending weakness, and respiratory failure. However, autonomic abnormalities are common, and symptoms are rapidly progressive (hours rather than weeks) and do not worsen with repetition.

 The action of acetylcholine at the postsynaptic membrane is terminated by acetylcholinesterase, not by acetylcholine reuptake. Organophosphates (eg, pesticides, sarin gas) irreversibly inactivate acetylcholinesterase, causing cholinergic toxicity (eg, increased glandular secretions, widespread smooth muscle activation). Muscle weakness, including respiratory failure, can occur due to depolarizing blockade at the neuromuscular junction; however, other symptoms (eg, diarrhea, urination, miosis, bradycardia, emesis, salivation) would be expected.

Gram-positive bacilli (rods)

 Gram-positive bacilli (rods) subdivide according to their ability to produce spores. Bacillus and Clostridia are spore-forming rods while Listeria and Corynebacterium are not. Spore-forming rods that produce spores can survive in environments for many years.

https://www.ncbi.nlm.nih.gov/books/NBK470553/ 

 Inside each fascicle, each muscle fiber is encased in a thin connective tissue layer of collagen and reticular fibers called the endomysium.

 Sarin is a potent nerve agent used as a chemical weapon.  It is highly lethal, even at small concentrations, causing death in only a few minutes.  Sarin was outlawed as a "weapon of mass destruction" in 1993 as part of the UN Chemical Weapons convention.  Sadly, reports of sarin use continue, with most recent concerns centering around incidents in the Syrian civil war.  Sarin works by inhibiting the activity of acetylcholinesterase.

How do you think sarin would impact the muscles?

How could you justify those predicted impacts based on the chemical interactions at the neuromuscular junction?
Resources & Reminders

If desired, you could re-watch the video at this address (https://www.youtube.com/watch?v=8Hu5W_tFXLs) and review your book

Links to an external site., paying special attention to the role of acetylcholinesterase.

Consider specifically...

    Based on the information above, which parts of the video/book description would be most directly affected by sarin?
    What are the normal roles of those parts in muscle stimulation?
    What would happen differently in the presence of sarin and why?


Structure of Skeletal Muscle Explained in simple terms

Sliding Filament Theory | Muscle Contraction

Muscle Contraction - Cross Bridge Cycle, Animation.

Musculoskeletal System | Neuromuscular Junction | Sliding Filament Theor...

Neuromuscular Junction Muscle Contraction Part 1 Anatomy Tutorial NSCA C...

Muscle Contraction Part 1 Events at the Neuromuscular Junction

The contraction of a striated muscle fiber occurs

  The contraction of a striated muscle fiber occurs as the sarcomeres, linearly arranged within myofibrils, shorten as myosin heads pull on the actin filaments

Wound healing versus fibrosis

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