Lecture 17-18- Muscle Physiology

Question 1

The outer layer of the sarcolemma attaches to the…

Answer 1

Tendon

Question 2

Is actin or myosin the Thin Filament?

Answer 2

Actin

Question 3

A-band

Answer 3

gray area with actin and myosin

Question 4

M line

Answer 4

inside the H zone, middle of the myosin/sarcomere

Question 5

What structure intertwines with actin?

Answer 5

Tropomyosin, with troponin bound

Question 6

What does troponin bind?

Answer 6

calcium

Question 7

What does SR stand for?

Answer 7

Sarcoplasmic reticulum

Question 8

What does the SR surround?

Answer 8

myofibrils

Question 9

What does the SR store until muscle contraction

Answer 9

Calcium

Question 10

What are invaginations of the SR that aid in depolarization?

Answer 10

T tubules

Question 11

Order of events leading to muscle contraction after Ach is released at NMJ

Answer 11

Ach activates nicotinic receptors on sarcolemma
Na channels open causing depolarization
Ca released from SR
COntraction

Question 12

If there is less Ca available (milk fever) then what happens at the NMJ

Answer 12

less Ach is released –> less depolarization –> less contraction

Question 13

What is parturient paresis in dogs called?

Answer 13

Puerperal tetany

Question 14

Why is milk fever different between dogs and cows?

Answer 14

Dog cell membranes become more permiable to Na during hypocalcemia, aiding in depolarization

Question 15

what happens when troponin binds to Ca

Answer 15

allows myosin and actin to bind

Question 16

What happens to ATP when actin and myosin bind?

Answer 16

ATP is hydrolyzed and actin is pulled

Question 17

How are ADP and P released from myosin?

Answer 17

ATPase

Question 18

Why does rigor mortis occur?

Answer 18

There is no ATP to release contraction

Question 19

What are Type I muscle fibers?

Answer 19

Slow twitch

Question 20

What are the qualities of slow twitch fibers?

Answer 20

Darker color
Myoglobin
more mitochondria
More aerobic

Question 21

What are Type II muscle fibers?

Answer 21

Fast twitch

Question 22

What are qualities of Type II muscle fibers?

Answer 22

Larger
Extensive SR
fatigue quickly
More powerful

Question 23

What is the energy source of slow twitch fibers?

Answer 23

Oxidative phosphorylation

Question 24

What are the two classes of Type II fibers?

Answer 24

A: intermediate between slow and fast
B: traditional fast twitch

Question 25

Endurance canine athletes use what for fuel?

Answer 25

Fatty acids

Question 26

Sprinters have more of what type of muscle fiber?

Answer 26

Type II

Question 27

What is a motor unit?

Answer 27

LMN and all of the innervated muscle fibers

Question 28

Movement begins with small or large motor units?

Answer 28

small

Question 29

Is the sarcoplasmic reticulum more developed in cardia muscle or skeletal muscle

Answer 29

Skeletal muscle

Question 30

What type of muscle cell does not have T tubules?

Answer 30

Smooth muscle

Question 31

What type of muscle cell can be innervated by more than one neuron?

Answer 31

Smooth muscle

Question 32

Characteristics of Multiunit Smooth Muscle

Answer 32

Autonomic neuron intwines around each muscle cell Delicate movement Each fiber can contract independently

Question 33

Characteristics of Single unit smooth muscle

Answer 33

Contraction of many cells at once (peristalsis) cell membranes joined by gap junctions, allowing action potentials to travel between

Question 34

What are calveoli

Answer 34

invaginations in smooth muscle SR similar to T tubules

Question 35

Can smooth muscle receive inhibitory signals?

Answer 35

No

Question 36

What do smooth muscle cells have instead of NMJ?

Answer 36

Varicosities allowing large areas of smooth muscle to be affected at the same time

Question 37

What does smooth muscle have instead of troponin/tropomyosin?

Answer 37

Calmodulin

Question 38

What happens to smooth muscle once calcium binds calmodulin?

Answer 38

Activation of the myosin light-chain kinase

Question 39

What does smooth muscle use instead of ATP to cock myosin heads?

Answer 39

Myosin light-chain kinase

Question 40

What dephosphorylates the myosin light-chain kinase?

Answer 40

myosin phosphatase