Functional Anatomy

Question 1

What is the Epimysium

Answer 1

Connective tissue surrounding each muscle

Question 2

What is the permimysium

Answer 2

Connective tissue that surrounds the fasicle

Question 3

What is a fasicle

Answer 3

Bundle of skeletal muscle fibres

Question 4

what is a myofibril

Answer 4

Comprised of actin and myosin

Question 5

Actin

Answer 5

Thin myofilament

Question 6

Myosin

Answer 6

Thick myofilament

Question 7

Motor end plates

Answer 7

attaches axon terminals to muscle fibers

Question 8

Whats a sarcomere

Answer 8

contractile component of muscle fiber, comprised of actin and myosin

Question 9

Z-line

Answer 9

Dark thin protein band, to which actin filaments are attached in muscle fiber, making boundaries in adjacent sarcomeres’

Question 10

A-band

Answer 10

Center of sarcomere containing both actin and myosin filaments

Question 11

H-zone

Answer 11

Center of A-band, free from myosin cross bridges

Question 12

I-band

Answer 12

The area of myofibril containing ONLY actin

Question 13

M-line

Answer 13

Found in H-zone, middle of sarcomere

Question 14

What is a motor unit

Answer 14

A single motor neuron and all of the corresponding muscle fibers

Question 15

All or nothing principle

Answer 15

When eletrical impulses reach a certain THRESHOLD all of the muscle fibres in the motor unit will contract at the same time, as forcefully as possible

Question 16

Explain fibre recruitment

Answer 16

• increase number of motor units recruited: increases strength of nerve impulses sent from the brain(stronger impulse) more activated muscle fibres
• increased frequency of motor unit discharge: Greater frequency of arrival of nerve impulses = greater force production

Question 17

Whats is preferential recruitment

Answer 17

Recruitment of the type of muscle fibre is determined by the intensity of the task

• endurance=slow twitch
• speed endurance= fast twitch a
• speed/power= fast twitch b

Question 18

Role of the brain in the nervous control of muscular contraction

Answer 18

interprets information and makes a decision on sensory input to then send messages to muscles to contract and movement occurs

Question 19

Role of the spinal cord in the nervous control of muscular contraction

Answer 19

Part of the central nervous system (CNS) that connects with the peripheral nervous system (PNS)
Pathway for motor information relaying information between the brain –> body and body –> brain.

Question 20

Sensory Neuron

Answer 20

Conveys nerve impulses to spinal cord bases on the information picked up from stimulus/ sensory receptors

Question 21

Motor Neuron

Answer 21

Moves impulses away from the CNS and effectively activates movements

Question 22

Characteristic of slow twitch muscle fibre (type 1)

Answer 22

-slow contraction speed
-low force of contraction
-high capacity for ATP production
-fatigue resistant
-contracts repeatedly for continuous activity
-posses high amounts of aerobic characteristics:
increased myoglobin, mitochondria, capillary density
-smaller fibres
-stimulated by smaller motor neurons

Question 23

Characteristics of fast twitch muscle fibre (type2b)

Answer 23

• rapid contraction speed
• high force of contraction
• large muscle fibres
• large motor unit stimulates muscle fibres
• posses anaerobic characteristics: increased glycotic enzymes, increased PC stores, increases glycogen
• simulated by large motor neurons
• fatigues quickly

Question 24

Characteristics of a fast twitch muscle fibre (type 2a)

Answer 24

• fast contraction speed
• moderate force of contraction
• relatively large muscle fibres
• stimulated by relatively large motor neurons
• possesses some aerobic characteristics: moderate levels of mitochondria, myoglibin and capilaries
• fatigue resistant (less than slow twitch)

Question 25

Force-length relationship

Answer 25

The force of muscle varies with varring muscle lengths
Max force is produced when the muscle is at resting length/ mid point of muscle
as cross bridge formation reaches optimal

Question 26

Force-Velocity relationship

Answer 26

The force created increases with velocity of shortening, the force the muscle resits increases with increases velocity of lengthening

Max force is produced as velocity decreases, this is due to increased time to form optimal cross bridge formation

Max force is resisted when velocities increase as there is less time for actin and myosin cross bridges to detach