Week 5 - Muscles

Question 1

what are the 3 types of muscle ?

Answer 1

• cardiac muscle
• smooth muscle
• skeletal muscle

Question 2

what are the properties of cardiac muscle ?

Answer 2

• made of actin and myosin
• stimulated by node cells
• generates force through sliding filament mechanics

Question 3

what are the properties of cardiac muscle ?

Answer 3

• surround hollow structures

- generates force through sliding filament mechanisms

Question 4

what are the properties of skeletal muscle ?

Answer 4

• change in length = movement
• generates force through sliding filament mechanisms
• controlled by motor neurons (voluntary)

Question 5

what are the characteristics of a skeletal muscle fibre ?

Answer 5

• many mitochondria
• transverse tubules
• myofibrils and sarcomeres

Question 6

define sarcomella

Answer 6

plasma membrane

Question 7

define sarcoplasm

Answer 7

the cytoplasm of muscle cells

Question 8

define sarcoplasm reticulum

Answer 8

where Ca2+ is stored and released following muscle excitation

Question 9

what are thin filament made of ?

Answer 9

actin

Question 10

what are thick filaments made of ?

Answer 10

myosin

Question 11

what 2 proteins are bound to actin that prevent myosin from binding ?

Answer 11

• tropomyosin

- troponin

Question 12

define excitation

Answer 12

stimulation by a neauron

Question 13

what is the 1st stage of excitation-contraction coupling ?

Answer 13

Ca2+ released into t-tubles

Question 14

what is the 2nd stage of excitation-contraction coupling ?

Answer 14

Ca2+ released from sarcoplasmic reticulum

Question 15

what is the 3rd stage of excitation-contraction coupling ?

Answer 15

Ca2+ binding to troponin removes tropomyosin from blocking myosin

Question 16

what is the 4th stage of excitation-contraction coupling ?

Answer 16

cross-bridged form between actin and myosin and generate force

Question 17

what is the 5th stage of excitation-contraction coupling ?

Answer 17

when action potential stops, Ca2+ is taken back into sarcoplasmic reticulum

Question 18

what is the 6th stage of excitation-contraction coupling ?

Answer 18

Ca2+ removal from troponin restores tropomyosin, blocking myosin binding to actin

Question 19

define motor unit

Answer 19

a motor neuron and the muscles fibres it stimulates

Question 20

define neuromuscular junction

Answer 20

a synapse between a motor neuron and a muscle

Question 21

what is the 1st stage of events that occurs at a neuromuscular junction ?

Answer 21

action potential is sent down the motor neuron

Question 22

what is the 2nd stage of events that occurs at a neuromuscular junction ?

Answer 22

Ca2+ enters voltage-gated channels

Question 23

what is the 3rd stage of events that occurs at a neuromuscular junction ?

Answer 23

acetylcholine is released from vesicle in motor neuron

Question 24

what is the 4th stage of events that occurs at a neuromuscular junction ?

Answer 24

acetylcholine binds to receptors on motor end plate, opening ion channels in muscle fibre

Question 25

what is the 5th stage of events that occurs at a neuromuscular junction ?

Answer 25

Na2+ enters muscle fibre = depolarization

Question 26

what is the 6th stage of events that occurs at a neuromuscular junction ?

Answer 26

current spreads from motor end plate to T-tubules

Question 27

what is the 7th stage of events that occurs at a neuromuscular junction ?

Answer 27

muscle fibre action potential initiated

Question 28

what is the 8th stage of events that occurs at a neuromuscular junction ?

Answer 28

action potential moves along T-tubules to sarcoplasmic reticulum

Question 29

define twitch contraction

Answer 29

the response of a muscle fibre to a single action potential

Question 30

what are the 3 phases of a twitch contraction ?

Answer 30

- latent period - contraction phase - relaxation phase

Question 31

what happens in the latent period of a twitch contraction ?

Answer 31

- the period of time from the action potential to the onset of contraction - the time delay is due to the excitation-contraction coupling

Question 32

what happens in the contraction phase of a twitch contraction ?

Answer 32

the time that tension is developing due to the cross-bridge cycling

Question 33

what happens in the relaxation phase of a twitch contraction ?

Answer 33

- the time that tension is decreasing (relaxing)

Question 34

define tetanic contraction

Answer 34

where force remains relatively constant for the period of activation

Question 35

type I: primary source of ATP

Answer 35

oxidative phosphorylation

Question 36

type IIa: primary source of ATP

Answer 36

oxidative phosphorylation

Question 37

type IIx: primary source of ATP

Answer 37

glycolysis

Question 38

type I: mitochondria

Answer 38

many

Question 39

type IIa: mitochondria

Answer 39

intermediate

Question 40

type IIx: mitochondria

Answer 40

few

Question 41

type I: capillaries

Answer 41

many

Question 42

type IIa: capillaries

Answer 42

many

Question 43

type IIx: capillaries

Answer 43

few

Question 44

type I: myoglobin content

Answer 44

high (red muscle)

Question 45

type IIa: myoglobin content

Answer 45

high (red muscle)

Question 46

type IIx: myoglobin content

Answer 46

low (white muscle)

Question 47

type I: glycolytic enzyme activity

Answer 47

low

Question 48

type IIa: glycolytic enzyme activity

Answer 48

intermediate

Question 49

type IIx: glycolytic enzyme activity

Answer 49

high

Question 50

type I: glycogen content

Answer 50

low

Question 51

type IIa: glycogen content

Answer 51

intermediate

Question 52

type IIx: glycogen content

Answer 52

high

Question 53

type I: rate of fatigue

Answer 53

slow

Question 54

type IIa: rate of fatigue

Answer 54

intermediate

Question 55

type IIx: rate of fatigue

Answer 55

fast

Question 56

type I: myosin-ATPase activity

Answer 56

low

Question 57

type IIa: myosin -ATPase acivity

Answer 57

intermediate

Question 58

type IIx: myosin-ATPase acivity

Answer 58

high

Question 59

type I: contraction velocity

Answer 59

slow

Question 60

type IIa: contraction velocity

Answer 60

fast

Question 61

type IIx: contraction velocity

Answer 61

fastest

Question 62

type I: fibre diameter

Answer 62

small

Question 63

type IIa: fibre diameter

Answer 63

large

Question 64

type IIx: fibre diameter

Answer 64

large

Question 65

type I: size of motor neuron innervating fibre

Answer 65

small

Question 66

type IIa: size of motor neuron innervating fibre

Answer 66

intermediate

Question 67

type IIx: size of motor neuron innervating fibre

Answer 67

large

Question 68

what are the 3 pathways by which ATP can be synthesized ?

Answer 68

- phosphorylation of ADP by creating phosphate - oxidation phosphorylation of ADP in mitochondria - glycolytic phosphorylation of ADP in the absence of oxygen

Question 69

define muscle cramp

Answer 69

an involuntary contraction of skeletal muscle that occurs during or immediately after exercise

Question 70

what are the two hypotheses surrounding muscle cramp

Answer 70

- electrolyte depletion and dehydration | - altered neuromuscular control

Question 71

what is the electrolyte depletion and dehydration hypothesis ?

Answer 71

- change in sodium potassium, magnesium, or calcium concentration in plasma - no prospective studies to support

Question 72

what is the altered neuromuscular control hypothesis ?

Answer 72

- altered reflex control due to fatigue | - excitatory input overwhelms inhibitory input

Question 73

define delayed onset of muscle soreness

Answer 73

microdamage to muscle which in minor inflammation and pain

Question 74

define muscular dystrophy

Answer 74

- weakening and breakdown of muscle over time | - results in premature death

Question 75

what is Duchenne muscular dystrophy ?

Answer 75

mutation in a gene on the X chromosome that codes for the protein dystrophin

Question 76

what is dystrophin ?

Answer 76

extremely large protein that forms links between myofibrils and sarcolemma