Topic 10 - SKELETAL MUSCLE PHYSIOLOGY

Question 1

name 4 muscle characteristics

Answer 1

1. excitable
2. contractile
3. extensible
4. elastic

Question 2

muscle characteristic: excitable

Answer 2

respond to stimuli by producing action potentials

Question 3

muscle characteristic: contractile

Answer 3

can shorten, thicken

Question 4

muscle characteristic: extensible

Answer 4

stretch when pulled

Question 5

muscle characteristic: elastic

Answer 5

return to original shape after contraction or extension

Question 6

name 4 muscle functions

Answer 6

1. movement (walking, breathing)
2. posture, facial expression
3. heat production - 37º
4. protection of viscera - body wall

Question 7

neuromuscular junction

1. each _____ _____ (cell) innervated by _____ _ _______
2. axon of ______ ______ branches to _______ several _______ fibres
   
   1. _ ______ ⇒ approx. 150 fibres ______ the same ______ muscle
3. a single ______ ______ + ALL the ______ _____ it innervates = a _____ unit

Answer 7

• each muscle fibre (cell) innervated by only 1 neuron
• axon of motor neuron branches to innervate several muscle fibres
  
  • 1 neuron ⇒ approx. 150 fibres within the same whole muscle
• a single motor neuron + ALL the muscle fibres it innervates = a motor unit

Question 8

neuromuscular junction

1. _____ muscle fibre (___) _______ by only 1 neuron
2. ____ of motor neuron _______ to innervate _______ muscle fibres
3. 1 neuron ⇒ approx. ___ _______ within the ____ whole _______
4. a ______ motor neuron + ___ the muscle fibres it _______ = a motor ____

Answer 8

1. each muscle fibre (cell) innervated by only 1 neuron
2. axon of motor neuron branches to innervate several muscle fibres
3. 1 neuron ⇒ approx. 150 fibres within the same whole muscle
4. a single motor neuron + ALL the muscle fibres it innervates = a motor unit

Question 9

neuromuscular junction

no hints (4 points)

Answer 9

1. each muscle fibre (cell) innervated by only 1 neuron
2. axon of motor neuron branches to innervate several muscle fibres
3. 1 neuron ⇒ approx. 150 fibres within the same whole muscle
4. a single motor neuron + ALL the muscle fibres it innervates = a motor unit

Question 10

neuromuscular junction

structure

1. ________ ____ (neuron) with ____ in vesicles
2. postsynaptic cell (_____) membrane (__________) - specialized region with ___ _________ (=motor end plate)
3. ___ membranes ________ by synaptic cleft

Answer 10

1. presynaptic cell (neuron) with ACh in vesicles
2. postsynaptic cell (muscle) membrane (sarcolemma) - specialized region with ACh receptors (=motor end plate)
3. two membranes separated by synaptic cleft

Question 11

neuromuscular junction

structure

1. presynaptic cell (_____) with ACh __ _____
2. ___________ ______ (muscle) __________ (sarcolemma) - ________ _____ with ACh

receptors (=____ _____ _____)

3. two _______ separated by ______ _____

Answer 11

1. presynaptic cell (neuron) with ACh in vesicles
2. postsynaptic cell (muscle) membrane (sarcolemma) - specialized region with ACh receptors (=motor end plate)
3. two membranes separated by synaptic cleft

Question 12

neuromuscular junction

structure

no hints (3 points)

Answer 12

1. presynaptic cell (neuron) with ACh in vesicles
2. postsynaptic cell (muscle) membrane (sarcolemma) - specialized region with ACh receptors (=motor end plate)
3. two membranes separated by synaptic cleft

Question 13

neuromuscular junction

function (steps)

1. ___ reaches ______ ______ and synaptic end bulb of neuron
2. Ca++ _____ via voltage gates ⇒ causes ________ of _____
3. ____ binds to ____ _______ on motor end plate
4. Chemical gates _____ and Na+ ______ ⇒ EPP (________ GP)
5. EPP causes _______ of Na+ ______ gates on adjacent ________ ⇒ ___ (AP has same properties/channels as __ _ _____) - propagates ______ _________

Answer 13

1. AP reaches axon terminal and synaptic end bulb of neuron
2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
3. ACh binds to ACh receptors on motor end plate
4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
5. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Question 14

neuromuscular junction

function (steps)

1. AP _____ axon terminal and _____ ____ _______ of neuron
2. ____ enters via ______ _____ ⇒ _______ exocytosis of ACh
3. ACh ____ __ ACh receptors on ____ ____ _____
4. ________ ______ open and ___ enters ⇒ ____ (depolarizing ___)
5. ____ causes opening of _____ voltage gates on _______ sarcolemma ⇒ AP (AP has same ________________ as on a neuron) - _________ along sarcolemma

Answer 14

1. AP reaches axon terminal and synaptic end bulb of neuron
2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
3. ACh binds to ACh receptors on motor end plate
4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
5. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Question 15

neuromuscular junction

function (steps)

1. 2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
2. 4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
3. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ ???????

Answer 15

1. AP reaches axon terminal and synaptic end bulb of neuron
2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
3. ACh binds to ACh receptors on motor end plate
4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
5. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Question 16

neuromuscular junction

function

1. AP reaches axon terminal and synaptic end bulb of neuron
2. 3. ACh binds to ACh receptors on motor end plate
3. 5. ??????? ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Answer 16

1. AP reaches axon terminal and synaptic end bulb of neuron
2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
3. ACh binds to ACh receptors on motor end plate
4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
5. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Question 17

neuromuscular junction

function

what are the 5 steps

no hints

Answer 17

1. AP reaches axon terminal and synaptic end bulb of neuron
2. Ca++ enters via voltage gates ⇒ causes exocytosis of ACh
3. ACh binds to ACh receptors on motor end plate
4. Chemical gates open and Na+ enters ⇒ EPP (depolarizing GP)
5. EPP causes opening of Na+ voltage gates on adjacent sarcolemma ⇒ AP (AP has same properties/channels as on a neuron) - propagates along sarcolemma

Question 18

1 AP (neuron) ⇒ _________ ⇒ __________

i.e. always a critical stimulus because (3 things)

1. lots of ___ released
2. motor end plate has _______ ________
3. therefore, to inhibit _______ ______, must inhibit _______ ______

Answer 18

1 EPP ⇒ 1 AP (Always)

1. lots of ACh released
2. motor end plate has many receptors
3. therefore, to inhibit skeletal muscle, must inhibit motor neuron

Question 19

1 AP ⇒ 1 EPP ⇒ 1 AP (Always)

i.e. always a critical stimulus because:

1. lots of ACh ________
2. _______ ____ _______has many receptors
3. therefore, to ______ skeletal muscle, must ______ motor neuron

Answer 19

1 EPP ⇒ 1 AP (Always)

1. lots of ACh released
2. motor end plate has many receptors
3. therefore, to inhibit skeletal muscle, must inhibit motor neuron

Question 20

1AP ⇒ 1 EPP ⇒ 1 AP (Always)

i.e. always a critical stimulus because??

3 points

Answer 20

1AP ⇒ 1 EPP ⇒ 1 AP (Always)

1. lots of ACh released
2. motor end plate has many receptors
3. therefore, to inhibit skeletal muscle, must inhibit motor neuron