Functional Anatomy

Question 1

structure of skeletal muscle

Answer 1

epimysium
fascicle
perimysium
muscle fibre
myofibril

Question 2

Fascicle

Answer 2

a bundle of skeletal muscle fibres surrounded by the perimysium.

Question 3

Epimysium

Answer 3

connective tissue sheath surrounding each muscle.

Question 4

Perimysium

Answer 4

connective tissue which surrounds each bundle of muscle fibres

Question 5

Muscle fibre

Answer 5

surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm. Amuscle fibreis composed of many fibrils, which give the cell its striated appearance.

Question 6

Endomysium

Answer 6

connective tissue which surrounds each muscle fibre.

Question 7

Myofibril

Answer 7

small thread like strands that run through each muscle fibre.

Question 8

What is the slidinbg flimaent theory

Answer 8

Explains the shortening of the sarcomere (in a concentric contraction) and the resulting contraction of the muscle.

Question 9

Explain the sliding filament theory

Answer 9

When there is a neurochemical stimulation, calcium ions are released from the sarcoplasmic reticulum into the sarcomere prompting a reaction in each muscle fibre between the myosin and the actin filaments.
Myosin filaments creates crossbridges (myosin heads) at regular intervals. These cross bridges attach and reattach at different times along the actin pulling on them to create movement and maintain tension
This causes the actin to move into the centre of the sarcomere, shortening the myofibril and causing the actin and myosin filaments to be almost fully overlapped when in a fully contracted position causing the H Zone and I band disappear.
As each sarcomere shortens, so does the total length of each muscle fibre
When the contraction finishes, the myosin and actin filaments return to a relaxed position (ATP releases energy causing myosin to detach from the actin and crossbridge is broken)

Question 10

H.A.I.Z

Answer 10

H zone (distance between the actin filaments)
A band (length of the myosin filament)
I band (distance from the edge of myosin to the Z-Line)
Z line (edge of the sarcomere)

Question 11

during contraction

Answer 11

H zone disappears/becomes smaller.
I band disappears/becomes smaller.
A band does not change in size.

Question 12

motor unit

Answer 12

is the motor neuron and all the muscle fibres with which it connects to and stimulates.

Question 13

small motor unit

Answer 13

innovates a small number of muscle fibres and are not strong, but they provide subtle and precise control.

Question 14

large motor unit

Answer 14

innovates a large number of muscle fibres and are strong with little fine control.

Question 15

dendrites of sensory neurons

Answer 15

pass impuluse/signal from the sensory receptors to the cell body of the sensory neurons/eye

Question 16

axon of motor neurons

Answer 16

transmit impulse/signals away from cell body to the muscle fibres

Question 17

neuron

Answer 17

a cell within the nervous system that transmits impulse/signals to other nerve cells/muscle

Question 18

spinal cord

Answer 18

transmit impulse/signal from the brain to parts of the body

Question 19

motor unit

Answer 19

causes contraction of the associated muscle fibres

Question 20

force-velocity relationship

Answer 20

describes the inverse relationship between force production and the velocity of movement.

Question 21

Concentric contraction

Answer 21

as more force is required the speed of movement cannot be as fast (or as less velocity is required the more force can be produced).

Question 22

Eccentric contraction

Answer 22

as more force is required muscle velocity increases. As less force is required muscle velocity decreases.

Question 23

Force – length relationship

Answer 23

relates directly towards the amount of muscle force that can be produced at a varying muscle length.
When full flexed/extended (out range of the contraction), not as much force can be produced, compared to the mid-range (resting length).
The force length relates directly to the mid-range (resting length) of a muscle the greatest force production can be generated due to the maximal / optimal overlap of actin and myosin.

Question 24

All or none

Answer 24

motor unit receives stimulation/impulses/action potential to threshold, all the muscle associated with that motor unit will contract to their maximum level (all at the same time). Producing maximum force: more/greater number of motor units are used, activating large motor units, recruits appropriate muscle type 11

Question 25

Muscle fibre - Type IIa

Answer 25

Fast contraction speed – used for speed endurance based activities
Moderate force of contraction
Fatigue resistance but not as much as slow twitch fibres
Generate greater force and more powerful contractions as they are larger than red fibres
Possess some aerobic characteristics such as moderate levels of myoglobin, mitochondria and blood capillaries
Stimulated by relatively large motor neurons and are stimulated at a moderate frequency
E.g. 200m / 400m(up to 70% fast twitch)

Question 26

Muscle fibre - Type IIb

Answer 26

Rapid contraction speed – used for speed, strength and power based activities
High force of contraction
High capacity for anaerobic ATP production
Fatigue very quickly – no oxygen
Generate greater force and more powerful contraction as they are larger than red fibres
Possess very few aerobic characteristics such as low levels of myoglobin, mitochondria and blood capillaries, but very high anaerobic characteristics such as high levels of glycogen
Stimulated by very large motor neurons and are stimulated at a very high frequency
E.g. 100m / 200m Sprinter, High / Long Jumper, Thrower (up to 80% fast twitch),

Question 27

Muscle fibre - Type 1

Answer 27

Slow twitch
Slow contraction speed – used for endurance activities
Low force of contraction
High capacity for ATP production – generates ATP using the aerobic system
Fatigue resistant
Contract repeatedly for continuous activity
Possess more aerobic characteristics such as high levels of myoglobin, mitochondria and blood capillaries
Stimulated by relatively small motor neurons and are stimulated at a low frequency
E.g. 10,000m / Marathon Runner, Endurance swimmer / cyclist (up to 80% slow twitch)

Question 28

How the process of brain reciving signal

Answer 28

1. Brain receives a signal from the sensory nerve
2. Message travels via motor neurons- Structure Slide
3. Arrives at the neuromuscular junction and has to cross the synapses (RIVER/GAP)
4. Arrival of Action Potential which opens calcium channels Ca+ ions.
5. Influx of calcium triggers a biochemical cascade 6. This causes the release of Acetylocholine which is a neurotransmitter into the syapse.
6. Signal on the end plate then transmit nerve signals to the muscle fibre.
7. This signal releases the calcium from the sarcoplasmic reticulum causing Sliding Filament Theory
8. Nerves cells extend across the length of the Myofibril BUT only stimulate portions of the muscle belly

Question 29

relationship between muscle contraction and nerve function

Answer 29

In order for muscles to contract or shorten, muscle fibres must be stimulated by nerve or electrical impulses sent via motor neurons.
The sensory neurons receive a stimulus (such as the starter gun) and sends electrical impulse to the brain (Central nervous system).
A message is sent from the brain, in the form of an action potential, down the spinal cord through to the motor neuron.
The motor neuron receives the signal and transmits it to the muscle fibre, which activates muscle movement.