Week 9 Lecture

Question 1

_________ surrounds each muscle fiber and and encloses its contents

Answer 1

Sarcolemma

Question 2

________ contains the cell nuclei of muscle fiber

Answer 2

Sarcoplasm

Question 3

two main anatomical features of myosin

Answer 3

Polypeptide tail

Globular head

Question 4

___________ activates the myosin heads during crossbridging

Answer 4

ATP hydrolysis

Question 5

What enzyme splits ATP in the cross bridge

Answer 5

ATPase

Question 6

Skeletal muscle fibres differ in what three characteristics ?

Answer 6

• the primary mechanisms they use to produce ATP
• the type of motor neuron innervation
• the type of myosin heavy chain expressed

Question 7

What are the four common characteristics of type 1 fibers ?

Answer 7

1. Low myosin ATPase activity
2. Slow calcium handling ability and shortening speed
3. Less developed Glycolytic capacity
4. Large and numerous mitochondria

Question 8

What 6 main areas is the brain divided into ?

Answer 8

Medulla

Pons

Midbrain

Cerebellum

Diencephalon

Telencephalon

Question 9

What is the role of the Pyramidal tract ?

Answer 9

Activates skeletal musculature in voluntary movement

Question 10

What is the role of the Extrapyramidal tract

Answer 10

Controls posture and muscle tone

Question 11

What tasks may the reticular formation be involved in?

Answer 11

Posture during movements

CV

Respiration m

Sleep-wake Cycle

Question 12

What are the five common features of the NMJ

Answer 12

1. Schwann cells
2. ACH in terminal section of neuron
3. Basement membrane lining synaptic space
4. ACH receptors
5. Microtubules to transmit electrical signal to fiber

Question 13

What three factors produce neuronal facilitation?

Answer 13

1. Decreased sensitivity of the motor neuron to inhibitory neurotransmitters
2. Reduced quantity of inhibitory neurotransmitter substance transported into motor neuron
3. Combined effect of both mechanisms

Question 14

How are motor units classified ?

Answer 14

Based on the properties of the fibers they innervates. Properties:

• twitch characteristics
• tension characteristics
• fatigability

Question 15

What is Sarcopenia ?

Answer 15

Age-related loss of muscle mass

Question 16

Sarcopenia is due to what?

Answer 16

Decrease in muscle size

Decrease in number of fibers

Question 17

Describe the Actin filament structure

Answer 17

Two twisted monomers, bound my Tropomyosin polypeptide chains

Question 18

What are the two main descending pathways

Answer 18

Pyramidal

Extrapyramidal

Question 19

What is the reticular formation?

Answer 19

A set of interconnected Nuclei, located throughout the brain stem

Question 20

The reticular formation integrates information from what structures

Answer 20

• Spinal cord
• cerebral cortex
• Basal Ganglia
• Cerebellum

Question 21

The number of muscle fibres per motor neuron relates to what?

Answer 21

That particular muscles movement function

Question 22

IPSP is a result of what

Answer 22

Increased resting cell membrane potential

Question 23

What 2 mechanisms determine the force of a muscle contraction

Answer 23

Number of recruited motor units

Frequency of motor unit discharge

Question 24

List 2 changes to neural function with age

Answer 24

40% decrease in number of spinal cord axons

10% decrease in nerve conduction velocity

Question 25

Name the four mechanisms that contribute to declined endurance performance with age

Answer 25

1. Decreased max. HR
2. Decreased max. SV
3. Decreased max. a-vO2 difference
4. Lactate Threshold change