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FAP Year 1 > Muscles > Flashcards

Muscles Flashcards

1
Q

What is muscle?

A

contractile tissue which serves to bring about movement

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2
Q

What does muscles contraction and relaxation bring about?

A
  1. Body movement
    - Movement of body levers
    - Enables locomotion via articulations
  2. Posture maintenance
    - Stabilisation of bony levers and articulations
    - Enables body position to be maintained
  3. Body substance movement / transport / storage
    - Movement and storage of digesta, blood, urine, etc within the body
  4. Heat generation
    - Conversion of ATP into muscle movement is inefficient
    - Only 25%of ATP energy produces muscle movement
    - Remaining 75% is converted to heat
    - Heat helps maintain body temperature
    - In cold environments involuntary contraction of skeletal muscle (shivering) further helps
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3
Q

What are the three types of muscle?

A

skeletal
cardiac
smooth

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4
Q

What is skeletal muscle?

A

voluntary
attached to skeleton
striated

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5
Q

How is muscle structured?

A

Fibres arranged in bundles known as fasicles

Surrounded by endomysium

Multiple bundles surrounded by perimysium

Muscle surrounded by epimysium

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6
Q

What are sarcomeres?

A

makes up muscle fibre and gives muscle a striated look

contraction occurs through sarcomeres through chemical reaction causing myosin and acts to bind and contract

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7
Q

How does contraction of the muscle occur?

A
  • Contraction cycle consists of excitation phase, contraction phase and relaxation phase
  • Excitation phase (aka latent period) involves stimulus arriving at the neuromuscular junction
  • Stimulus is transmitted to motor end plate
  • Sarcolemma depolarises
  • Action potential propagated from sarcolemma to t-tubules and then sarcoplasmic reticulum
  • Ca ions released into sarcoplasm
  • Ca bind with troponin causing troponin-tropomyosin complex to move from actin chain
  • Lasts ~ 5msec
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8
Q

What occurs in the Contraction Phase?

A
  • Adenosine Trihosphate ATP on myosin head hydrolysed to Adenosine Diphosphate (ADP) and Inorganic Phosphate (P)
  • Myosin head moves and attaches to actin chain
  • Hydrolysed P released triggering power stroke
  • Once energy used up movement stops
  • ATP from sarcoplasm binds to mysoin and another power stroke triggered
  • Sequence is repeated whislt [Ca ion] is high
  • Lasts 20-200 msec
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9
Q

What occurs the the relaxation phase?

A
  • Action potential ends
  • Ca actively pumped back into the sarcoplasmic reticulum
  • Takes 10-100 msec
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10
Q

What is the refractory period?

A
  • This is time period where a muscle has received one stimulus to contract and cannot respond to a further stimulus
  • ~ 5 msec for skeletal, ~300 msec for cardiac
  • Further stimulus after the refractory period leads to increased muscle contraction (summation) – due to only partial relaxation
  • Stimuli arriving at 80-100 / sec cause tetanic contraction
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11
Q

What are the three skeletal muscle fibre types?

A

Type I – slow oxidative
Type IIA – fast oxidative-glycolytic
Type IIB – fast glycolytic
•The ‘type’ refers to the form of myosin present
•The three forms of myosin have different ATPase activities and hence different contraction speeds

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12
Q

What is type I skeletal muscle?

A
  • Narrow
  • Least forceful
  • Aerobic only
  • Contain large numbers of mitochondria
  • Supplied by large numbers of capillaries
  • Contain large concentration of myoglobin
  • Slow contractions (~ 100-200msec)
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13
Q

What is type IIA skeletal muscle?

A
  • Intermediate diameter
  • Intermediate forces
  • Large numbers of mitochondria
  • Large concentrations of myoglobin
  • Supplied by large number of capillaries
  • Produce ATP aerobically and anaerobically
  • Faster contraction speed (<100msec)
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14
Q

What is type IIB skeletal muscle?

A
  • Widest
  • Produce greatest forces
  • Supplied by relatively few capillaries
  • Small number of mitochondria
  • Low concentration of myoglobin
  • High glycogen content
  • Anaerobic
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15
Q

What is distribution of fibres within muscles determined by?

A

Muscle function
Genetics
Exercise and training

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16
Q

How does exercise effect muscle fibre types?

A
  • Postural muscles have high type I contents
  • Exercise stimulates conversion from IIA to IIB and vice versa
  • Increased muscle use causes hypertrophy – due to increased nervous stimulation. More myofibrils, mitochondria and sarcoplasmic reticulum. Stronger
  • Lack of use causes fibre atrophy – due to lack of stimulation causing loss of myofibrils
  • Type I fibres most affected
17
Q

What are the four properties of muscle tissue?

A
  1. Excitability – muscle responds to stimuli and produces action potential for movement
  2. Contractility - muscle responds to an action potential by producing a force
  3. Extensibility - ability of muscle to stretch (without damage) and still exert a force
  4. Elasticity - muscle always returns to its resting state (length, shape, etc.) after contraction is finished or following extension
18
Q

How many muscle layers does the horse have?

A

4
cutaneous trunci- first layer that can spasm

superficial layer- large, broad muscles, production of locomotion

middle layer- more finer tuned movements eg; steering

deep layer- smaller and densely compact muscles that are involved in posture and stabilisation of joints

19
Q

How many muscle layers does the dog have?

A

4
cutaneous trunci

superficial layer- large, broad muscles, production of locomotion

middle layer- more finer tuned movements eg; steering

deep layer- smaller and densely compact muscles that are involved in posture and stabilisation of joints

20
Q

What does intrinsic mean?

A

stays within a system eg; muscle with origin and insertion in axial skeleton

21
Q

What does extrinsic mean?

A

crosses systems eg; muscle with origin in axial skeleton but insertion in appendicular

22
Q

What are the different muscle shapes?

A

fusiform () eg; biceps brachii

parallel I I eg; rectus abdominis

convergent V eg; latissimus dorsi

unipennate /J eg; found in limbs

bipinnate U eg; rectus femoris

Multipennate. \U/ eg; deltoid

Circular O eg; internal muscles- in digestive system

23
Q

What is concentric contraction?

A

shortening contraction

24
Q

What is isotonic contraction?

A

change in length with constant force

25
Q

What is ballistic contraction?

A

contraction with momentum

26
Q

What is eccentric contraction?

A

lengthening contraction, whilst still under control (resisting gravity)

27
Q

What is ballistic contraction?

A

eccentric or concentric contraction with momentum (gives extra degree of movement)

28
Q

What is a synergist muscle action?

A

acts to help the agonist at a specific joint

29
Q

How are muscles classified?

A

by their actions at the joint

30
Q

What is a synergist muscle action?

A

acts to help the agonist at a specific joint- stabilises

31
Q

what are extensors?

A

extend the joint

32
Q

What are abductors?

A

move muscles/ joints away from the midline

33
Q

What are adductors?

A

move muscles/ joints back towards from the midline

34
Q

What is muscle tone?

A

All muscles will continually receive a small amount of stimuli from nervous system even when at rest with gives the muscle “resting tone”
•Some animals will have high resting tone some have low
•Resting tone can have an impact on muscular training

35
Q

What are muscle issues?

A
  • Adhesion
  • Hypertonicity
  • Spasm
  • Contracture
  • Ruptures
  • Injuries
  • Pathologies affecting muscle quality
36
Q

What are muscle issues?

A
  • Adhesion
  • Hypertonicity- increased tone in the muscles
  • Spasm- muscle turns on and off without control
  • Contracture- consistent message to muscle that make the muscle stay contracted
  • Ruptures- one or several muscle fibres break
  • Injuries- traumatic resulting in ruptures
  • Pathologies affecting muscle quality

FAP Year 1 (13 decks)

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