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PBL SEM 3 > 9 - skeletal muscle, cartilage and bone histology > Flashcards

9 - skeletal muscle, cartilage and bone histology Flashcards

1
Q

functions of skeletal muscle

A
  • moves and stabilises the skeleton
  • forms sphincters in digestive and urinary tracts
  • involved in respiration
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2
Q

name 4 characteristics of skeletal muscle

A
  • long, cylindrical cells
  • striated
  • multiple, peripherally located nuclei
  • innervated by somatic nervous system
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3
Q

what is endomysium?

A

connective tissue layer surrounding a single muscle fibre

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4
Q

what is a fascicle?

A

bundle of muscle fibres

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5
Q

what is the name given to the connective tissue layer surrounding a fascicle?

A

perimysium

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6
Q

what is a group of fascicles called?

A

muscle

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7
Q

what is epimysium?

A

connective tissue layer surrounding a muscle

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8
Q

describe slow twitch muscle fibres

A
  • type 1
  • involved in aerobic respiration
  • red — rich myoglobin and mitochondria
  • rich blood supply (rich capillary beds)
  • generate more ATP for continuous, extended contraction
  • fire more slowly
  • resist fatigue
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9
Q

describe fast twitch fibres

A
  • type II
  • use anaerobic respiration
  • good for short bursts of strength or speed
  • fatigue quickly
  • few mitochondria and little myoglobin
  • white — less extensive blood supply
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10
Q

type IIa vs IIb muscle fibres

A

IIa — intermediate fast twitch, use both aerobic and anaerobic respiration

IIb — use only anaerobic

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11
Q

who is most likely to have type I/II fibres?

A

I — marathon runners

II — sprinters, jumpers, weight lifters

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12
Q

all the fibres of a single ______ are of the same type

A

motor unit (an individual motor neuron and all the muscle fibres that it innervates)

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13
Q

what detect fibre length?

A

sensory stretch receptors = muscle spindle

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14
Q

how does muscle spindle lie in relation to muscle fibres?

A

in parallel

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15
Q

what does muscle spindle consist of?

A
  • spindle cells — 2 types = nuclear bag fibres and nuclear chain fibres - surrounded by an internal capsule
  • internal capsule within fluid filled space surrounded by an external capsule
  • sensory nerve endings wrapped around spindle cells — detect stretch
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16
Q

what happens when a muscle fibre is stretched?

A

receptors stretched — reflex — muscle shortens

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17
Q

what kind of innervation do spindle cells also receive? function?

A

motor innervation from CNS by gamma neurons — regulates sensitivity of receptor

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18
Q

what are the functions of cartilage?

A
  • framework in resp tract
  • shock absorption and facilitation of joint movement
  • covers articular surfaces
  • development of long bones
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19
Q

cartilage consist of what cartilage cells suspended in an ECM?

A
  1. chondrogenic cells — stem cells : differentiate into chondroblasts
  2. chondroblasts — immature cells
  3. chondrocytes — mature cells : maintain matrix
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20
Q

most cartilage is surrounded by what?

A

perichondrium = connective tissue layer

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21
Q

cartilage is ___ so gains nutrients via diffusion

A

avascular

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22
Q

what are the 3 types of cartilage?

A

hyaline, elastic and fibrous

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23
Q

what are the 2 types of cartilage growth?

A
  1. appositional — occurs just deep to the perichondrium
  2. interstitial — occurs within actual tissue of cartilage - in areas with no perichondrium. occurs by mitosis of chondrocytes
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24
Q

where is hyaline cartilage found?

A

= most common form of cartilage in the body

  • articulating surfaces, resp tract (nasal septum, larynx, trachea, bronchi), costal cartilages, epiphyseal plates of developing long bones
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25
Q

what are the functions of hyaline cartilage?

A
  • provides structural support for the resp tract
  • forms a smooth surface at joints to enable free movement
  • involved in the development and growth of long bones
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26
Q

why does the ECM in hyaline cartilage appear smooth and glassy?

A

because the fibres and ground substance are of similar refractive properties

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27
Q

what type collagen fibres does hyaline cartilage contain?

A

type II collagen fibres

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28
Q

what are chondrocytes located in in hyaline and elastic cartilage?

A

lacunae

29
Q

what does hyaline cartilage possess (except over articular surfaces)?

A

perichondrium

30
Q

in hyaline cartilage in areas where interstitial growth is occurring, the chondrocytes appear in clusters termed what?

A

isogenous groups

31
Q

territorial vs inter territorial matrix

A

territorial — surrounds chondrocytes

inter territorial — between chondrocytes

32
Q

functions of elastic cartilage

A

provides elasticity and firm support

33
Q

what does elastic cartilage contain?

A

type II collagen fibres plus numerous elastic fibres in the matrix

34
Q

why can elastic cartilage have both appositional and interstitial growth?

A

possesses a perichondrium

35
Q

gives examples of elastic cartilage in the body

A

auricle, epiglottis, corniculate and cuneiform cartilages

36
Q

where is fibrocartilage located?

A

where support and tensile strength are required — it is very tough

iv discs, menisci, symphysis pubis

37
Q

functions of fibrocartilage

A
  • resistant to tearing and compression
  • prodigies strength and resilience

located where support and tensile strength are required — it is very tough

38
Q

what does the matrix of fibrocartilage contain?

A

type II collagen fires and large bundles of type I collagen fibres

39
Q

fibrocartilage consists of alternating layers of what?

A

hyaline cartilage matrix and thick layers of dense collagen fibres

40
Q

how are chondrocytes arranged in fibrocartilage?

A

chondrocytes are small and few and arranged in parallel rows along side the fibres

41
Q

how does growth of fibrocartilage occur and why?

A

via interstitial growth as no perichondrium

42
Q

what kind of cartilage is this?

A

elastic

43
Q

what kind of cartilage is this?

A

fibrocartilage

44
Q

what kind of cartilage is this?

A

hyaline

45
Q

what is the organic component of bone? describe

A

osteoid = glycoproteins ground substance with type 1 collagen fibres
- strong, flexible, but easily compressed

46
Q

what is the inorganic component of bone? descirbe

A

mineral salts mainly calcium hydroxyapatite
- hard, relatively inflexible and quite brittle

47
Q

describe osteoblasts

A
  • produce new bone
  • secrete osteoid
  • responsible for mineral deposition
  • as osteoblasts surround themselves with ECM, they become trapped in their secretion and become osteocytes
48
Q

describe osteocytes

A
  • mature bone cells
  • cannot divide
  • located in lacunae within the bone
  • maintain the matrix
49
Q

as the ____ mineralises, the _____ become entombed between the lamellae in ______ where they mature into osteocytes

A
  • osteoid
  • osteoblasts
  • lacunae
50
Q

describe osteoclasts

A
  • remove mineral from the matrix
  • responsible for bone remodelling
  • large and multi nucleated
51
Q

describe osteogenic stem cells

A

aka osteoprogenitor cells

  • found in periosteum and endosteum
  • develop into osteoblasts
52
Q

bone consists of what 2 types of tissue?

A

compact bone and cancellous (spongy) bone

53
Q

why are osteons in compact bone aligned in the same direction?

A

to increase unidirectional strength

54
Q

what is in haversian canals in compact bone?

A

blood vessels

55
Q

what surrounds the haversian canal?

A

sheets of bone - concentric lamellae

56
Q

where are osteocytes in compact bone?

A

in lacunae between concentric lamellae

57
Q

osteocytes in compact bone communicate with each other via what?

A

canaliculi

58
Q
  • continuous resorption and re disposition of compact bone results in new haversian systems being found amongst partially resorped systems
  • the remnants of the partially resorbed systems form ________ (between __________)
A

form interstitial lamellae (between concentric lamellae)

59
Q

what is the lamellar bone that surrounds the outside of the bone called?

A

circumferential lamellae

60
Q

blood vessels from the periosteum enter through ________ and communicate with the vessels in the ______

A
  • enter through Volkmann canals (perpendicular channels)
  • haversian canal
61
Q

trabeculae of cancellous bone is arranged haphazardly to form a network of interconnecting struts designed to provide what?

A

maximum strength for minimum mass

62
Q

what do spaces between trabeculae in spongy bone contain?

A

bone marrow

63
Q

where do osteocytes in cancellous bone lie?

A

lie in lacunar near the surface of the trabeculae (instead of between lamellae like in compact bone)

64
Q

how are trabeculae orientated in cancellous bone?

A

along the lines of stress

65
Q

what do yellow and red bone marrow contain?

A

yellow — adipocytes
red — haematopoietic stem cells

66
Q

spongy bone contains no ____ or _____ unlike compact bone

A

Volkmann’s or Haversian canals

67
Q

a sheet of bone that encircles an osteon is termed a what?

A

concentric lamellae

68
Q

fibrocartilage increases size by what?

A

interstitial growth

69
Q
A

PBL SEM 3 (49 decks)

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