Lecture 7 Test 3

Question 1

Skeletal muscle force generation

Answer 1

works when you have a muscle stretched to its natural state and a contraction force is measured after an action potential.

It won’t work if the muscle is over stretched or under stretched

Question 2

(heart) Load/contraction velocity

Answer 2

increased load = decreased muscle contraction speed

Question 3

What is quantal summation?

Answer 3

Number of motor units activated to produce more force of contraction

Question 4

What is temporal summation?

Answer 4

When you reach max Force generation compared to rate stimulation. Ex. 40 Hz caused a continuous contraction (tetany)

Question 5

What is tetany?

Answer 5

Ex. 40 Hz (supra maximal voltage)

When the AP aren’t able to go back to resting potential and Ca++ aren’t able to fully return into the SR. Causing another AP while previous Ca++ are still in the cytoplasm, resulting with continued contraction without rest.

Question 6

What is atrophy?

Answer 6

When muscles get smaller after no use.

Question 7

Which part of the muscles are affected by atrophy first?

Answer 7

Microfibrils

Question 8

Can heart muscles replace dead muscles?

Answer 8

Yes and we don’t know this is happening

Question 9

What happens to vascular beds when you workout?

Answer 9

When you have big healthy muscles, vascular beds get big as well.

Question 10

How much skeletal muscles are there in a body?

Answer 10

40% of body mass

Question 11

How many smooth muscles are there in a body?

Answer 11

10% of BW

Question 12

Where can you find smooth muscles?

Answer 12

ex. airway, intestines, eyes, blood vessels

Question 13

Compare the cross bridge process of skeletal muscles to smooth muscles.

Answer 13

in smooth muscles, slower pace, causing “latching” d/t the myosin head takes a longer time to release from the actin

Question 14

T/F: Smooth muscles are a lot stronger than skeletal muscles.

Answer 14

True

Question 15

smooth muscle strength is similar to what animal?

Answer 15

Boa constrictor strength with the continuous contraction

Question 16

Smooth muscles are connected to their neighbors by

Answer 16

Gap junctions

Question 17

Ratio for smooth muscle

Answer 17

Actin: Myosin
20:1

Question 18

Skeletal muscle ratio

Answer 18

Actin:Myosin
2:1

Question 19

(Skeletal muscle) actin filament anchor via

Answer 19

Z disk

Question 20

(Smooth muscle) actin filament anchor via

Answer 20

Dense bodies

Question 21

Skeletal muscles have huge stores of?

Answer 21

Calcium in the SR

Question 22

How are smooth muscles depolarized?

Answer 22

It has very leaky channels for calcium and sodium
V-G Ca ch
Ligand gated Ca ch
Some under developed SR

Question 23

What happens if your Ca++ is 0??

Answer 23

No BP, No Ca++ induced heart beat, Smooth muscles won’t contract, no tone.

Question 24

What is a visceral smooth muscle?

Answer 24

Unitary smooth muscle = functions as a unit spreading calcium amongst each cell via gap junctions

Question 25

Ex. of visceral smooth muscle

Answer 25

Intestines

Question 26

What is a multi unit smooth muscle and what is it used for?

Answer 26

Used for fine tune movements. Not dependent on gap junctions but is dependent on a neurotransmitter

Question 27

Ex. of multi unit smooth muscle?

Answer 27

Ciliary muscles, Iris

Question 28

Ex. of a hybrid of skeletal and visceral smooth muscle?

Answer 28

Esophagus

Question 29

Anatomy of a small artery (unitary smooth muscle)

Answer 29

Endothelium lined on the inside.Smooth muscle on the inside and connective tissue on the outside (Adventitia) structural support.

Question 30

What's the difference in anatomy between blood vessel and capillary?

Answer 30

Capillary only has endothelium. no smooth muscles.

Question 31

3 layers of blood vessel

Answer 31

Tunica intima Tunica media Tunica externa.adventitia

Question 32

Difference between smooth muscle and skeletal muscle contraction

Answer 32

skeletal muscles can shorten a little. and smooth muscles can shorten a lot. M line is empty.

Question 33

How does ACh work in different receptors?

Answer 33

varies per receptor Vascular beds = relaxation Small Intestines = contraction

Question 34

How are actin sites found in smooth muscles?

Answer 34

It is always exposed

Question 35

Does myosin do anything in smooth muscles?

Answer 35

Nothing, it's just there

Question 36

Explain smooth muscle contraction process

Answer 36

highly dependent on Ca++ influx Ca++ influx (leak, V-G, SR) > binds to calmodulin > Ca++ calmodulin complex > CAM kinase phosphorylate MLC > activates MLCK > contracts > Ca++ efflux > Myosin phosphatase removes phos > relaxation

Question 37

What other ways can you relax the smooth muscle?

Answer 37

Ca++ put back in SR PMCA- plasma membrane calcium atp-ase Na+/Ca++ exchanger (3:1)

Question 38

How else can you reduce MLCK activity?

Answer 38

* Nitrates > cGMP > PK-G > phosphorylate MLCK > reduce activity * PK-G > phosphorylate Ca++ ch > inactive

Question 39

How does ACh or bradykinin cause vascular relaxation?

Answer 39

ACh/bradykinin binds to a receptor > Ca++ release from ER > binds to calmodulin > eNOs > binds to Arginine > NO > binds to cGMP > PK-G > phosphorylate Ca entry channels > closes gate > vascular relaxation

Question 40

What does PDE-5 (sildenafil) do to vascular smooth muscle?

Answer 40

increase cGMP > increase PK-G > vascular relaxation

Question 41

What was PDE-5 previously used for?

Answer 41

treatment for Pulm HTN resulted with new treatment plan

Question 42

signal transduction cascade with A1, serotonin

Answer 42

A1 agonist > PIP-C > IP3, DAG (increase activity PK-C) > Ca++ from SR > binds calmodulin > activate

Question 43

Special fact about serotonin

Answer 43

constrict brain blood vessel

Question 44

Brain blood vessels only respond to one thing and not catecholamines

Answer 44

serotonin

Question 45

T/F: Calcium leakage can cause smooth muscle contraction without AP

Answer 45

True

Question 46

some smooth muscles can generate rhythmic motions in order to...

Answer 46

to produce some type of contraction

Question 47

Heart contraction process

Answer 47

Na+ influx > AP > (20%) Ca influx L-ype (T-type faster) > Ca induced Ca release from SR (80%) > contraction > 80% via SERCA > 20% via Na+/Ca++ exchanger 3:1 and Ca++ atpase

Question 48

What is calsequestrin?

Answer 48

A protein that helps the SERCA pack Ca++ into a container and remove it from the solution. Found in any muscle with an SR.

Question 49

What is phospholamban?

Answer 49

Inhibitor for the SERCA to allow ca+ to stay longer in the heart for a longer contraction.

Question 50

B1 receptor process

Answer 50

B1 agonist > activates Adenylyl cyclase > activates cAMP > PK-A > contraction

Question 51

ACh receptor process

Answer 51

ACh binds m-ACH-R > inhibit adenylyl cyclase > reduce cAMP > relaxation