Exam 3- Muscles

Question 1

function of muscular system

Answer 1

movement

Question 2

term for a single cell

Answer 2

muscle fiber

Question 3

moving skeleton

Answer 3

skeletal muscle

Question 4

moving contents, usually within a tube, it surrounds

Answer 4

smooth muscle

Question 5

pumping blood

Answer 5

cardiac muscle

Question 6

neurons who’s axons innervate SM fibers- somatic

Answer 6

motor neuron

Question 7

somatic motor neurons and the skeletal muscle fibers it innervates

Answer 7

motor unit

Question 8

allow contraction strength to vary due to number of motor units active

Answer 8

graded contractions

Question 9

-Ca2+ enables ACh to be released across the space between the axon terminal and the motor end plate
-ACh binds to nicotinic ACh receptors
*Electrical excitation of a muscle results in muscle contraction
—Meaning: Nervous system stimulates muscle fiber, action potential in muscle fibers contracts it

Answer 9

excitation-contraction coupling

Question 10

thick filaments: made almost entirely of __

Answer 10

myosin

Question 11

polypeptide chains form two globular heads and a tail

Answer 11

thick filaments: myosin

Question 12

area that exerts force on the thin filament

Answer 12

heads of myosin forms crossbridge

Question 13

thin filaments: mostly made of the protein ___ and also includes the regulatory proteins ___ and ___

Answer 13

actin; troponin & tropomyosin

Question 14

overlaps binding sites blocking cross bridge

Answer 14

tropomyosin

Question 15

Ca2+ binding to _____ regulates skeletal muscle contraction bc it moves the tropomyosin away and allows myosin to interact with the actin

Answer 15

troponin

Question 16

• AP starts in Muscle Cell
• T-tubule Voltage gated calcium channel: open when membrane is depolarization
• Direct link to Ca2+ release channels in Sarcoplasmic reticulum
• Relaxation results as Ca2+ is pumped into S. Reticulum when AP stop

Answer 16

the neuromuscular junction: post-synaptic-muscle cell

Question 17

• Initiated when excitation-contraction coupling increases cytosolic Ca2+ and binding sites on actin are exposed

Answer 17

the cross-bridge cycle

Question 18

what step of the CBC?

the active site on actin is exposed as Ca2+ binds troponin

Answer 18

step 1

Question 19

what step of the CBC?

the myosin head forms a cross bridge with actin

Answer 19

step 2

Question 20

what step of the CBC?

during the power stroke, the myosin head bends, and ADP and phosphate are released

Answer 20

step 3

Question 21

what step of the CBC?

a new molecule of ATP attached to the myosin head, causing the cross bridge to detach

Answer 21

step 4

Question 22

what step of the CBC?

ATP hydrolyzes to ADP and phosphate, which returns the myosin to the “cocked” position

Answer 22

step 5

Question 23

what is happening in steps 1 & 2 of CBC

Answer 23

bind actin + myosin –> lose phosphate

Question 24

what is happening in step 3 & 4 of CBC

Answer 24

lose ADP powerstroke

Question 25

what is happening is step 5 & 6 in CBC

Answer 25

gain ATP & gain energy

Question 26

The overlapping thick and thin filaments in each sarcomere move past each other, propelled by movements of the cross-bridges. Filaments do not change length but slide. - I band decreasing in length

Answer 26

sliding filament mechanism

Question 27

excitation = contraction coupling __ Ca2+

Answer 27

decreases

Question 28

Excitation =. AP, depolarized, all from neuron up until _____

Answer 28

Ca2+ release

Question 29

fluid in skeletal muscle

Answer 29

sarcoplasm

Question 30

cell membrane

Answer 30

sarcolemma

Question 31

- ______ muscles surround hollow structures and organs that undergo changes in volume with accompanying changes in the lengths of the smooth muscle fibers. ex. stomach, intestines, blood vessels

Answer 31

smooth muscle

Question 32

in smooth muscle nerves are part of _____ division

Answer 32

autonomic (instead of somatic division like other muscle types)

Question 33

in smooth muscle calcium bind to ____

Answer 33

calmodulin (NO troponin in smooth muscle)

Question 34

how smooth differs from other muscle types

Answer 34

- Smooth muscle cells (SMC) have a single nucleus and have the capacity to divide throughout the life of an individual. - The thick and thin filaments are not organized into myofibrils, and there are NO sarcomeres.

Question 35

sources of cytosolic Ca2+ (Two sources of Ca2+ contribute to the rise in cytosolic Ca2+ that initiates smooth muscle contraction)

Answer 35

1. The sarcoplasmic reticulum 2. Extracellular Ca2+ entering the cell through plasma-membrane Ca2+ channels.

Question 36

sources of cytosolic Ca2+: To relax, the Ca2+ has to be removed using the _______

Answer 36

Ca-ATPase pump

Question 37

action potentials spontaneously in the absence of any neural or hormonal input

Answer 37

pacemaker cells

Question 38

___ ___ holding Ca2+ concentrations high is termed latch state where muscle holds tension for long periods. - Ex. sphincter muscles of the GI tract.

Answer 38

prolonged stimulation

Question 39

- striated and use the sliding filament mechanism to contract - myocardium contracts fully every time its stimulated - hold the appearance of skeletal filaments & T-tubule - arranged like smooth muscle: around a hollow tube w/ gap junctions

Answer 39

cellular structure of cardiac muscle

Question 40

pacemaker potentials are regulated by ____ innervation

Answer 40

autonomic

Question 41

the heart cannot exhibit ___ & ____

Answer 41

summation & tetanus

Question 42

why cant the heart exhibit summation & tetanus

Answer 42

- due to refractory period - due to filling heart with blood

Question 43

_____is initiated by one AP (one electrical followed by one mechanical event)

Answer 43

one heart beat

Question 44

- The sequence of events from an action potential that activates force-generating mechanisms - This occurs in skeletal, smooth and cardiac muscles - In all muscles there is an increase in cytosolic Ca2+concentration

Answer 44

excitation-contraction coping in all muscle types