Chao 9

excitation contraction coupling steps

1. Action potential will enter axon terminal, calcium will also go into axon terminal allowing ACh to dock onto synaptic cleft

2. ACh will attach itself to the receptors of ligand gated channel which will open and allow sodium to go in

3. Once sodium is on motor end plate, turns into end plate potential since there is a difference in charge from - to +

4. End plate potential doesn’t stay in one place so it spreads, causing a new channel to open (voltage sodium gated channel) which allows more sodium to go in

5. Action potential occurs since positive charges are spread throughout sarcolemma. Starts going down t tubules

6. Opens DHP channel, which will automatically open RYR channel and release calcium

7. Calcium will flood down to the cell

8. Released calcium (the key) will bind to troponin (the gatekeeper) to move tropomyosin (the gate) out of the way to expose myosin’s binding site on actin

9. Will form a cross bridge, phosphate will be removed from ADP

10. Actin will move towards m like of Sarcomere

11. ATP binds myosin’s head, detaching from actin causing relaxation

12. Myosine ATPase turns ATP into ADP+phosphate to cause contraction

Smooth muscle contraction

1. Calcium goes into cell and binds with calmodulin

2. Both activate myosin light chain kinase

3. Mlck phosphorylates myosin light chains

4. Myosin’s interacts with cross bridge formation and filaments slide pass

5. Cell contracts

6. Relaxation happens when calcium is removed and mysoin light chain removes phosphate

When muscles contract

• Sarcomeres shorten

• H band shortens (or disappears)

• I band shortens

• Z discs move closer

• a bands move closer together

• Zone of overlap get bigger

What does rigor morris mean

Rigidity of death

• muscles don’t contract

• ATP depletion

What is i band made of and what does it do when muscle contracts

Made of thin actin filaments, shortens

What is A band made of and what does it do when muscles contract

Thick myosin filaments, moves closer together

What is h band made of and what does it do when muscles contract

Myosin, shortens

Where is m band located

Middle of h

What is z discs made of and what does it do when it contracts

Actinin move closer

What connects myosin to z disc

Titin

What are the two lines on the right and left ends

Z line

What is the slightly lightened area in the middle

H band

The line in the middle

M line

What are the darkened areas in the middle, on the sides of the lightened line

zone of overlap

What is the white square

I band

What is the dark square

A band

Starting from the two black lines going in, what id that called

Sarcomere

What does ACh bind with

Nicotinic Cholinergic receptors

ATP is for what

Contraction

Adp is for what

Relaxing

What neurotransmitter triggers muscle contraction

ACh

What ions are released by sarcoplasnic reticulum

Calcium

What are the end borders of the sarcomere

Z line

Which bands shortens when contracted in the sarcomere

I band and h band

(H can disappear

What causss contraction from a muscle relaxation

Myosine ATPase turns ATP to Adp +phosphate which causes contraction also ACh

What causes relaxation

ATP binds to Myosine head and detached from actin