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year 1 - dentistry > muscles and joints > Flashcards

muscles and joints Flashcards

1
Q

what type of tissue is muscle and what is its function

A
  • contractile tissue

- essential for movement in animals

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2
Q

what are the three types of muscles

A
  • smooth
  • skeletal (also known as striated or voluntary muscle)
  • cardiac
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3
Q

what is smooth muscle composed of

A
  • small oval cells

- containing an irregular pattern of contractile protein fibres hence why it appears smooth under a microscope

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4
Q

how is smooth muscle function regulated

A
  • by the autonomic nervous system and is capable of long sustained contractions eg. those in the visceral tissue
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5
Q

where is skeletal muscle found and what is often connected to

A
  • it is widespread throughout the body and often connected to bones
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6
Q

what is skeletal muscle composed of

A
  • composed of cells containing regular arrays of contractile proteins (mainly actin and myosin)
  • this gives skeletal muscle its striated (stripy) appearance
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7
Q

what is the skeletal muscle controlled by

A
  • the somatic nervous system and is capable fo short, vigorous contractions
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8
Q

what is the cardiac muscle composed of

A
  • only found in the heart
  • branched muscle fibres
  • joined by intercalated discus (desmosomes and gap junctions) - allows movement of ions
  • central placed nucleus
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9
Q

what are the length of contraction for cardiac muscle and what is it controlled by

A
  • short duration contraction

- intrinsic contraction modified by autonomic nervous system - has its own rhythmic beat

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10
Q

what are the three layers of connective tissue in skeletal muscle

A
  • epimysium - around entire bulk of muscle
  • endomysium - around individual muscle fibres
  • perimysium - around fascicles

endomysium fuses with tendon
tendon fuses with bone

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11
Q

what are muscle fibres largely composed of and what are they made up of

A
  • composed of microfibrils

- made up of actin and myosin rich microfibrils

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12
Q

what is each microfibril made up of

A
  • myofilament (form functional unit)

- myofilaments contain actin and myosin filaments in specific arraignments)

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13
Q

what are the thick and thin filaments

A
  • myosin = thick filaments

- actin = thin filaments

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14
Q

what are the two types of muscle fibre

A
  • type 1 (slow twitch)

- type 11 A and B (fast twitch)

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15
Q

properties of slow twitch fibres

A
  • contains lots of mitochondria and capillaries
  • produces large amounts of energy slowly by aerobic metabolism
  • resistant to fatigue
  • contains myoglobin
  • slow contraction
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16
Q

properties of fast twitch fibres type 2A

A
  • contain small amounts of myoglobin
  • more extensive capillary network
  • mixture of oxidative and glycotic (anaerobic metabolism)
  • contract rapidly
  • some resistance to fatigue
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17
Q

properties of type 2b fibres

A
  • uses glycotic (anaerobic metabolism)
  • few capillaries, mitochondria
  • little myoglobin
  • produces large amounts of energy quickly therefore rapid contractions
  • early fatigue
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18
Q

how do muscles contract

A
  • muscle contraction occur when actin and myosin fibres making up the sarcomere slide over each other causing the sarcomere to shorten and therefore the whole muscle fibre
  • the shortening of the sarcomere form the striations
19
Q

what are the dark bands called

A
  • A bands (thick and thin filaments overlapping)
20
Q

what are the light bands called

A
  • I bands (made of actin)
21
Q

what is one sarcomere

A
  • z disk to z disk
22
Q

what is found between the microfibrils

A
  • mitochondria and sarcoplasmic reticulum
23
Q

what is the M band

A
  • myosin held together in centre
24
Q

what type of muscle fibres make up the postural muscles

A
  • mainly type 1
25
Q

what type of muscle fibres make up the arms, jaws, muscle of the eye

A
  • mainly type 2A and type 2B
26
Q

what is a motor unit

A
  • all muscle fibres innervated by a single motor neurone
27
Q

what does the ratio of motor nerves to muscle fibres determine

A
  • level of control

- high ratio will innervate lots of muscle fibres

28
Q

what is the force of muscle contraction controlled by

A
  • the number of activated motor units
29
Q

how many types of muscle fibres does one motor unit contain

A
  • only contains one type of muscle fibre - to meet the functional requirement, recruitment of different types of muscle fibres occur
30
Q

are all motor units always in use

A
  • no when some are fatigued, others can be recruited to maintain contraction
31
Q

what control system do muscles have

A

muscle spindles

32
Q

what detects change in length of a muscle

A
  • sensory receptors within the belly
33
Q

how do muscle spindles work

A
  • muscle spindles - detects change in muscles
  • muscle spindles contain intrafusal fibres that have their own innervation distinct from extrafusal fibres
  • sensory neurones from muscle spindles send information to the spinal cord and cerebellum (proprioception)
34
Q

as muscles acts what are there alterations in

A
  • length
  • tension
  • strength of contraction
35
Q

where is the synovial joint formed

A
  • formed between two or more bones enabling movement
36
Q

what does the shape of bone determine

A
  • mobility and stability
37
Q

what is good fit

A
  • stable joint but loses some mobility
38
Q

what is poor fit

A
  • very mobile but unstable
39
Q

what are the 5 characteristic features of synovial joints

A
  • articular cartilage
  • joint (synovial) cavity
  • synovial fluid
  • articular capsule
  • reinforcing ligaments
40
Q

why are boys covered by hyaline articular cartilage

A
  • for cushioning and smooth movement
41
Q

why is the synovial cavity filled with synovial fluid and where is secreted from

A
  • lubricates the joints and role is shock absorption

- secreted by synovial membrane on non articular surfaces

42
Q

where is the synovial fluid retained

A
  • in joints by capsule of connective tissue

- capsule is strengthened by ligaments to limit movement and strengthen joints

43
Q

what happens if a joint is moved too far in wrong position

A
  • stretch receptors fire and position readjusted
  • if position is not readjusted, pain endings will fire to reinforce warning
  • if still nothing done ligaments may stretch to stop dislocation of joint

year 1 - dentistry (24 decks)

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