Muscle Morphology and Mechanics Flashcards Preview

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Flashcards in Muscle Morphology and Mechanics Deck (21)
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1
Q

What shape is the pectoralis major?

A

Convergent

2
Q

What shape is the deltoid?

A

Multipennate

3
Q

What shape is the biceps brachii?

A

Fusiform

4
Q

Describe fasciculation and a disease where it becomes pathological.

A

Muscle twitching. Normal to have it slightly.

Pathological when excessive e.g. motor neuron disease

5
Q

Describe isotonic muscle contraction

A

Equal force, muscle changes in length to move the load.
Can be concentric: muscle shortens, e.g. to lift the load in the hand.
Or eccentric: muscle exerts force while being extended e.g. walking downhill. Linked to delayed onset muscle soreness.

6
Q

Describe isomeric muscle contraction

A

Constant length, variable extention.
e.g. hand grip
Has a profound effect on blood pressure

7
Q

Describe the difference between slow and fast twitch muscle fibres.

A

Slow - many mitochondria so not fatigueable

Fast - fewer mitochondria

8
Q

What is proprioception? Give a drug that can interfere with it.

A

Feedback control of movement, awareness of self.
Muscle spindles tell the brain about force and stretch. They are specialised muscle fibres with associated nerve endings, enclosed in a capsule.
Alcohol interferes with it.

9
Q

What is one motor unit?

A

A muscle fibre and the fibre it innervates. Signal molecules.

10
Q

Give an example of signal molecules used between the nerve end and muscle which is not a neurotransmitter.

A

Neurotropins e.g. neurotropin 3
Cytokines e.g. cardiotrophin-1
Insulin-like growth factor e.g. ILGF-1

11
Q

Where in the brain are motor control centres for the muscles found?

A

Cerebrum

12
Q

Describe hypotonia and give a disease which can cause it.

A
Loss of muscle tone.
Cerebral/spinal neural shock
Lesions of the cerebellum
Motor nerve lesions: polyneuritis
Primary degeneration of muscles: myopathy
13
Q

Describe excitation-contraction coupling

A

Action potential travels down t-tubules, activating the sarcoplasmic reticulum to release calcium ions.

14
Q

Describe spatial summation

A

More motor neurons are activated so more muscle fibres are recruited to develop an increased force.
Reflex pathway from muscle spindles, joint receptors and golgi tendon organs. Have a role in recruitment.

15
Q

Describe temporal summation

A

Contraction depends on the frequency of stimuli.

16
Q

What is electromyography used for?

A

In diagnosis of diseases disrupting muscle contraction, such as motor neuron disease.
Electrodes are places above or in the muscle to see if contraction and electrical signals match.

17
Q

What happens to calcium in muscle cells after contraction?

A

Most is pumped back into the sarcoplasmic reticulum, some binds calmodulin.

18
Q

State sources of energy for ATP that allows myosin head detachment from actin.

A

Stores, creatine phosphate, glycolysis, oxidative phosphorylation

19
Q

What causes muscle cramp?

A

Lactate build up

20
Q

What is peripheral fatigue?

A

A depletion of muscle glycogen which occurs within one minute if there is interrupted blood flow.

21
Q

Describe contracture

A

A state of continuous contraction. Due to depletion of ATP as myosin heads are unable to detach.
E.g. rigor mortis