Muscle mechanics

Question 1

length-tension relationship

Answer 1

isometric muscle contraction - tension develops at initial length before contraction
initial length-tension relationship curve made by varying muscle length at rest and measure isometric tension when muscle is maximally stimulated at that length
tension depends on muscle length before it is contracted

Question 2

optimal length

Answer 2

length at which tension development is maximal

skeletal muscle is usually near optimal

Question 3

what bacteria causes infection tetanus

Answer 3

clostridium tetani

Question 4

tetanus

Answer 4

uncontrollable spasms of skeletal muscles

Question 5

how does bacteria cause muscle spasm in tetanus

Answer 5

toxin blocks inhibitory synapses in CNS - increased activity in motor nerves

Question 6

opisthotonus

Answer 6

a state of severe hyperextension and spasticity in which an individual’s head, neck and spinal column enter into a complete “bridging” or “arching” position

Question 7

tetanus in relation to action potential

Answer 7

muscle fibre stimulated so rapidly it cannot relax between stimuli - maximal sustained contraction

Question 8

summation

Answer 8

stimulation closer together do not allow muscle to relax fully

Question 9

twitches time length

Answer 9

The muscle cell twitch can have a duration of a
few hundred milliseconds and is never refractory
can be activated to contract many times before can relax

Question 10

summation with tetanus

Answer 10

at high frequencies of activation, there is a build up of tension which, when it reaches a maximum level of tension is called complete tetanus

Question 11

staircase phenomenom

Answer 11

When a muscle is stimulated repetitively at a frequency below that which causes summation, there is a progressive increase in the tension developed with each twitch until a maximum twitch is reached

Question 12

classification of muscle by appearance

Answer 12

striated and unstriated

Question 13

striated muscle

Answer 13

skeletal

cardiac

Question 14

unstriated muscle

Answer 14

smooth muscle

Question 15

classification of muscle by innervation

Answer 15

voluntary and involuntary

Question 16

voluntary muscle

Answer 16

skeletal muscle

Question 17

involuntary muscle

Answer 17

cardiac muscle

smooth muscle

Question 18

morphology of skeletal muscle

Answer 18

long cylindrical

Question 19

morphology of cardiac muscle

Answer 19

branched

Question 20

morphology of smooth muscle

Answer 20

spindle or fusiform

Question 21

nuclei of skeletal muscle

Answer 21

multiple located peripherally

Question 22

nuclei of cardiac muscle

Answer 22

one or 2 located centrally

Question 23

nuclei of smooth muscle

Answer 23

one located centrally

Question 24

what muscle has no t tubules

Answer 24

smooth muscle

Question 25

t tubules of skeletal muscle form

Answer 25

triad with sarcoplasmic reticulum

Question 26

t tubules of cardiac muscle form

Answer 26

dyad with sarcoplasmic reticulum

Question 27

which muscles doesn’t have electrical coupling of cells

Answer 27

skeletal muscle

Question 28

electrical coupling of cells of cardiac muscle

Answer 28

yes - with intercalated disks contain gap junction

Question 29

electrical coupling of cells of smooth muscle

Answer 29

yes - gap junction

Question 30

what is skeletal muscle regenerated with

Answer 30

satellite cells

Question 31

what muscle cannot regeneration

Answer 31

cardiac muscle

Question 32

what muscle requires Ca2+ for contraction

Answer 32

smooth muscle

Question 33

what regulates crossbridge formation for contraction

Answer 33

cardiac muscle
skeletal muscle
Ca2+ binding to troponin

Question 34

what nerves or receptors control contraction of skeletal muscle

Answer 34

motor neurons

Question 35

what nerves or receptors control contraction of cardiac muscle

Answer 35

autonomic nerves

beta adrenergic agonists

Question 36

what nerves or receptors control contraction of smooth muscle

Answer 36

autonomic nerves

hormones

Question 37

2 types of smooth muscle

Answer 37

multiunit

visceral

Question 38

examples of visceral smooth muscle

Answer 38

• Intestine
• Uterus
• Bladder
• Ureters
• Ducts of exocrine glands
• Precapillary sphincters
• Small blood vessels

Question 39

examples of multiunit smooth muscle

Answer 39

• Cilliary muscle
• Iris
• Piloerector muscles
• Large arteries and veins
• Arteriovenous shunt vessels
• Bronchial smooth muscle

Question 40

what regulates contraction of smooth muscle

Answer 40

Ca 2+ -calmodulin activation of myosin kinase and

phosphorylation of myosin

Question 41

what muscle does NOT cause summation of twitches by increased stimulus frequency

Answer 41

cardiac muscle