Muscle

Question 1

What are the three types of muscle

Answer 1

Skeletal (phasic + twitch)

Cardiac

Smooth (viscera/blood vessles)

Question 2

What is myosin

Answer 2

A complex group of proteins which form the motivating force in muscle contractions

Myosin heads contain an enzyme called myocinATPase

Question 3

What is Type 1 (I) Muscle fiber

Answer 3

Slow twitch muscle fibre

smallest fibre type

produces small amount of force when contracting

has high amounts of mitochondria as needs lots of O2 for energy

Highly fatigue resistant

Question 4

What is Type 2 (IIa) Muscle fiber

Answer 4

Moderate fast twitch

moderate size

uses oxygen and glucose as energy source

quick contracting speed and higher force output

reduced fatigue resistant compared to type 1

typically activated during anerobic exercise

Question 5

What is Type 2x (IIx) Muscle fiber

Answer 5

Fast twitch fibre

large size

generates most force

has lots of glucose stored as glycogen for energy

fibres fatigue quickly ( after 15-30seconds)

Question 6

What is hennemans size principle?

Answer 6

When muscle activity follows the order of type I, IIa then IIx. Once one of the fibres is fatigued then another fibre is activated.
This helps minimise muscle fatigue as allows precise motor control by using no more than the force needed to complete a movement

Question 7

Which muscle fibre is unique to dogs?

Answer 7

IId

It contains both IIa and IIx fibres making it good for multipurpose uses.

Question 8

Name the 4 muscle contractions and what they do

Answer 8

Concentric - active shortening (uses energy, actin/myosin is pulled together)

Eccentric - active lengthening (controlled, actin/myosin is pulled apart)

Isometric - constant length (stays the same length as the load changes)

Stretching - passive elongation (no energy required, actin/myosin is pulled apart through external forces)

Question 9

What is the main compound used to produce ATP?

Answer 9

Glucose

It is stored in the muscle and liver as glycogen and is easily broken down into glucose

Question 10

What are the differences between eccentric and concentric contractions

Answer 10

Eccentric is 80% more stronger than concentric due to more cross bridges stuck

Eccentric is more likely to damage connective tissues

Eccentric - actin/myosin pulled wrong way as muscle lengthens so more likely to cause injury

Concentric - actin/myosin is pulled together as the muscle shortens

Question 11

What are the three components needed for ATP regeneration in relation to muscle contraction

Answer 11

Mitochondrial Respiration

First source is Mitochondrial Respiration during aerobic respiration

Phosphocreatanine

During high muscle activity or longer periods of exercise ATP is then produced through phosphocreatanine system. This is an anaerobic system where a phosphate group is added to ADP to turn it into ATP.

Glycolysis

Once phosphocreatanine stores have run out ATP is produced through Glycolysis. An anaerobic process. The byproduct of this is lactate which causes muscle fatigue.

Question 12

What are actin-myosin cross bridges?

Answer 12

When myosin heads attach and release from actin in a cycle

Question 13

Explain how a muscle contraction occurs

Answer 13

Nervous impulse occurs (excitation contraction coupling) which in tern moves the tropomysin revealing myosin binding sites

The myosin binds to the actin. Once bound it releases the phosphate molecule which creates the power stroke and the actin is pulled towards the middle of the sarcomere.

ADP molecule is then released.

New ATP molecule binds to myosin head which unbinds the actin and myosin.

ATP is then hydrolysed which cocks the myosin head back into position ready for another cycle when ADP - Phos molecules bind again.

Question 14

Explain the process of contraction coupling

Answer 14

Ach is released from synaptic terminals and depolarises muscle which triggers an action potential

AP goes down T tubules which triggers calcium release from the sytoplasmic reticulum

Calcium binds to the tropin which moves the tropomysin revealing the myosin binding sites on the actin

Myosin heads attach to the actin and cross bridge cycle occurs

Contraction terminates when calcium is pumped back into the sytoplasmic reticulum via ATP driven pumps. This then means tropomysin covers the myosin binding sites on the actin and no further contractions occur

Question 15

what are the 5 muscle energy sources and there ordered use.

Answer 15

1. Purine nucleodite (first few seconds)
2. Creatinine Phosphate - (1-15 sec)
3. Anaerobic Glycolysis (15-45sec)
4. Krebs cycle (30-45 sec)
5. Free fatty acids (Mins - hrs) - second wind

Lots of the energy sources overlap to ensure more than one supply of ATP is available.

Question 16

What are the four cardinal signs of inflammation

Answer 16

heat
redness
pain
swelling

Question 17

3 stages of muscle healing

Answer 17

Inflammation (first few days)
Regeneration (First week)
Fibrosis (2nd-3rd week post injury)

Question 18

How are muscle injury’s graded and what are the clinical signs and recovery times.

Answer 18

Grade 1 -
tear of only a few muscle fibres
minimal loss to strength and function
7-21 day recovery

Grade 2 -
More sever partial muscle tear
evident decrease in strength/function
2-3mth recovery

Grade 3 -
Complete rupture of muscle
complete loss of strength and function
6 month + recover (poss surgery)

Question 19

Why is pain and lameness reduced in muscle injuries?

Answer 19

The muscle belly doesn’t have any pain fibres + there are very minimal pain fibres around the outside of the muscle

Question 20

Two types of muscle injury

Answer 20

Over work = leads to DOMs, then CRAMP and if further exercise is carried out then it causes an intracellular acidosis leading to metabolic acidosis.

Physical damage = strain

Question 21

where does cramp occur

Answer 21

only in muscles which cross 2 joints