Functional Anatomy

Question 1

Order of Layers within a muscle belly

Answer 1

1. Epimysium
2. Muscle Belly
3. Perimysium
4. Fascicle
5. Endomysium
6. Muscle Fibres
7. Myofibrils
8. Sarcomere
9. Myofilaments

Question 2

Epimysium

Answer 2

Outer connective tissue that surrounds the muscle belly

Question 3

Perimysium

Answer 3

Middle connective tissue that surrounds the fascicle

Question 4

Endomysium

Answer 4

Inner connective tissue that surrounds the muscle fibres

Question 5

Muscle Belly

Answer 5

The muscle as a whole

Question 6

Fascicle

Answer 6

Bundle of muscle fibres surrounded by the perimysium

Question 7

Muscle Fibres

Answer 7

Individual muscle cells

Question 8

Myofibril

Answer 8

Individual strands of the muscle cell

Question 9

Sarcomere

Answer 9

Contractile unit of skeletal muscle, from one z-line to another

Question 10

Myofilament

Answer 10

Proteins of the myofibril (actin and myosin)

Question 11

Z-lines

Answer 11

Ending of one sarcomere, beginning of another

Question 12

Actin

Answer 12

Thin myofilament, attached to z-lines

Question 13

Myosin

Answer 13

Thick myofilament

Question 14

Myosin Crossbridges

Answer 14

Projections from myosin

Question 15

H-ZOne

Answer 15

contains just myosin

Question 16

I-Band

Answer 16

Contains just actin

Question 17

A-Band

Answer 17

COntains both (length of myosin)

Question 18

M-Line

Answer 18

Centre of the sarcomere

Question 19

Eccentric

Answer 19

Muscle length extends

Question 20

Concentric

Answer 20

Muscle length shortens

Question 21

Outline the steps in sliding filament theory

Answer 21

1. Neurochemical stimulations (acetylcholine) releases calcium from the Sarcoplasmic Reticulum
2. Calcium ions bind to troponin, changing the shape of actin, which moves tropomyosin exposing actin binding sites
3. Myosin heads attach to actin binding sites forming crossbridges
4. The breakdown of ATP releases energy causing the crossbridges to pull actin towards the m-line (power stroke)
5. Sarcomere shortens causing z-lines and h-zones to shorten as actin ‘slides’ over myosin.
6. Crossbridges attach and reattach to produce movement and maintain tension
7. When muscle impulse ends, muscle relaxes

Question 22

Force-velocity relationship

Answer 22

Force produced is dependant on the velocity of the contraction, this is due to the amount of crossbridges. When there is slow velocity, a high amount of force is produced due to high numbers of crossbridges and a slow sarcomere contraction. When there is high velocity, a low amount of force is produced as there is low crossbridge numbers and a fast sarcomere contraction.

Question 23

Force-muscle length relationship

Answer 23

Force produced is dependant on the starting length of a muscle. When a muscle is resting (in resting postition) there is optimal tension resulting in the greatest genertion of force, this is because there is optimal overlap between myosin and actin myofilaments. When a muscle is full contraction there is a lower generated force as overlap is too great and there is less crossbridge attachment. When a muscle is in full extension there is a lower generated force as overlap is too little and there is insufficient numbers of cross bridges.

Question 24

Nervous System functions

Answer 24

-recieves information from the body and environment and sends this information to the brain and spinal cord
-brain determines most suitable response
-brain sends commands to muscles to carry out selected response

Question 25

Central Nervous System is made up of?

Answer 25

Spinal Cord - sends information from the body to the brain and vice versa Brain - analyses information recieved from a sensory neruon - determines most suitable response - sends a message to targeted muscles

Question 26

What is the peripheral nervous system made of?

Answer 26

Sensory Division (Sensory Neurons) - carries meesages from the body and the environment to the CNS Motor Division (Motor Neurons) - carries messages from the brain to the muscles to respond

Question 27

All or none principle

Answer 27

When a motor unit receives a stimulus/action potential that exceeds their threshold, all associated muscle fibres contract to their maximum potential. Smaller units produce precise movements and require smaller AP's. Larger units produce gross motor skills and require larger AP's

Question 28

Preferential Recruitment

Answer 28

1st - Slow Twitch 2nd - Fast Twitch IIa 3rd - Fast Twitch IIb

Question 29

Ways to increase force production

Answer 29

- increase number of motor units recruited by increasing stimulus size -increase frequency of impulses