Functional Anatomy

Question 1

what is an epimysium ?

Answer 1

connective tissue sheath surrounding each muscle

Question 2

what is the fascicle?

Answer 2

bundle of skeletal muscle fibres surrounded by the perimysium

Question 3

what is the perimysium?

Answer 3

connective tissue which surrounds each bundle of muscle fibre

Question 4

what is muscle fibre?

Answer 4

long lengths of muscle cells that make up skeletal muscles

Question 5

what is the endomysium ?

Answer 5

connective tissue that surrounds each muscle fibre

Question 6

what are myofibrils?

Answer 6

small thread like strands that rum through each muscle fibre

Question 7

what are the steps to the sliding filament theory?

Answer 7

1. 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
   2.Breakdown of ATP releases energy to stimulate cross bridges
2. Myosin filaments attach to the actin via the myosin heads which creates crossbridges. These cross bridges attach and reattach at different times along the actin pulling on them to create movement and maintain tension
   4.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.
3. As each sarcomere shortens, so does the total length of each muscle fibre
4. 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 8

what is the function of a dendrite?

Answer 8

passes information from the sensory receptor to the cell body of the sensory neuron

Question 9

what is the function of a axon?

Answer 9

transmit electrical information away from cell body to the muscle fibre

Question 10

what is the function of the spinal cord?

Answer 10

transmit electrical messages from the brain to parts of the body

Question 11

what is the function of the motor unit ?

Answer 11

causes contraction of the associated muscle fibre

Question 12

what is the function of a neuron?

Answer 12

a cell within the nervous system that transmits impulses to other nerve cell

Question 13

how is a message transmitted?

Answer 13

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.
4. Influx of calcium triggers a biochemical cascade
5. 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 14

what is the all or nothing principle ?

Answer 14

if the electrical threshold of the motor neuron is reached than all the muscle fibres which are connected to the motor unit will contract at the same time and force

Question 15

how can you produce more force?

Answer 15

• greater number of motor units
  -type of fibre
  -size of motor unit

Question 16

what is the relationship between force and velocity?

Answer 16

• concentric contraction - the more force required the slower the movement
  -eccentric contraction - more force is required the faster the movement

Question 17

what is the relationship between force and length?

Answer 17

relates to the amount of muscle force that can be produced at varying lengths maximal force is produced at mid range

Question 18

what are the characteristics of type 2 a?

Answer 18

• fast contraction speed
• moderate force contraction
• medium fatigue resistance
• moderate levels of myoglobin, mitochondria, blood capillaries
  -stimulated with large motor with moderate frequency

Question 19

what are the characteristics of type 2 b?

Answer 19

-rapid contraction speed
-high force contraction
- fast fatigue
-high capacity for anaerobic ATP production
-high levels of glycogen
-low levels of myoglobin, mitochondria, blood capillaries
-stimulated with large motor with high frequency

Question 20

what are the characteristics of type 1?

Answer 20

-slow contraction speed
-low force contraction
-contracts repeatedly
-high force contraction
-fatigue resistance
-high levels of myoglobin, mitochondria, blood capillaries
-stimulated with small motor with low frequency