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
2
Q
name 4 characteristics of skeletal muscle
A
- long, cylindrical cells
- striated
- multiple, peripherally located nuclei
- innervated by somatic nervous system
3
Q
what is endomysium?
A
connective tissue layer surrounding a single muscle fibre
4
Q
what is a fascicle?
A
bundle of muscle fibres
5
Q
what is the name given to the connective tissue layer surrounding a fascicle?
A
perimysium
6
Q
what is a group of fascicles called?
A
muscle
7
Q
what is epimysium?
A
connective tissue layer surrounding a muscle
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
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
10
Q
type IIa vs IIb muscle fibres
A
IIa — intermediate fast twitch, use both aerobic and anaerobic respiration
IIb — use only anaerobic
11
Q
who is most likely to have type I/II fibres?
A
I — marathon runners
II — sprinters, jumpers, weight lifters
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)
13
Q
what detect fibre length?
A
sensory stretch receptors = muscle spindle
14
Q
how does muscle spindle lie in relation to muscle fibres?
A
in parallel
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
16
Q
what happens when a muscle fibre is stretched?
A
receptors stretched — reflex — muscle shortens
17
Q
what kind of innervation do spindle cells also receive? function?
A
motor innervation from CNS by gamma neurons — regulates sensitivity of receptor
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
19
Q
cartilage consist of what cartilage cells suspended in an ECM?
A
- chondrogenic cells — stem cells : differentiate into chondroblasts
- chondroblasts — immature cells
- chondrocytes — mature cells : maintain matrix
20
Q
most cartilage is surrounded by what?
A
perichondrium = connective tissue layer
21
Q
cartilage is ___ so gains nutrients via diffusion
A
avascular
22
Q
what are the 3 types of cartilage?
A
hyaline, elastic and fibrous
23
Q
what are the 2 types of cartilage growth?
A
- appositional — occurs just deep to the perichondrium
- interstitial — occurs within actual tissue of cartilage - in areas with no perichondrium. occurs by mitosis of chondrocytes
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
25
what are the functions of hyaline cartilage?
- 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
26
why does the ECM in hyaline cartilage appear smooth and glassy?
because the fibres and ground substance are of similar refractive properties
27
what type collagen fibres does hyaline cartilage contain?
type II collagen fibres
28
what are chondrocytes located in in hyaline and elastic cartilage?
lacunae
29
what does hyaline cartilage possess (except over articular surfaces)?
perichondrium
30
in hyaline cartilage in areas where interstitial growth is occurring, the chondrocytes appear in clusters termed what?
isogenous groups
31
territorial vs inter territorial matrix
territorial — surrounds chondrocytes
inter territorial — between chondrocytes
32
functions of elastic cartilage
provides elasticity and firm support
33
what does elastic cartilage contain?
type II collagen fibres plus numerous elastic fibres in the matrix
34
why can elastic cartilage have both appositional and interstitial growth?
possesses a perichondrium
35
gives examples of elastic cartilage in the body
auricle, epiglottis, corniculate and cuneiform cartilages
36
where is fibrocartilage located?
where support and tensile strength are required — it is very tough
iv discs, menisci, symphysis pubis
37
functions of fibrocartilage
- resistant to tearing and compression
- prodigies strength and resilience
located where support and tensile strength are required — it is very tough
38
what does the matrix of fibrocartilage contain?
type II collagen fires and large bundles of type I collagen fibres
39
fibrocartilage consists of alternating layers of what?
hyaline cartilage matrix and thick layers of dense collagen fibres
40
how are chondrocytes arranged in fibrocartilage?
chondrocytes are small and few and arranged in parallel rows along side the fibres
41
how does growth of fibrocartilage occur and why?
via interstitial growth as no perichondrium
42
what kind of cartilage is this?
elastic
43
what kind of cartilage is this?
fibrocartilage
44
what kind of cartilage is this?
hyaline
45
what is the organic component of bone? describe
osteoid = glycoproteins ground substance with type 1 collagen fibres
- strong, flexible, but easily compressed
46
what is the inorganic component of bone? descirbe
mineral salts mainly calcium hydroxyapatite
- hard, relatively inflexible and quite brittle
47
describe osteoblasts
- 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
describe osteocytes
- mature bone cells
- cannot divide
- located in lacunae within the bone
- maintain the matrix
49
as the ____ mineralises, the _____ become entombed between the lamellae in ______ where they mature into osteocytes
- osteoid
- osteoblasts
- lacunae
50
describe osteoclasts
- remove mineral from the matrix
- responsible for bone remodelling
- large and multi nucleated
51
describe osteogenic stem cells
aka osteoprogenitor cells
- found in periosteum and endosteum
- develop into osteoblasts
52
bone consists of what 2 types of tissue?
compact bone and cancellous (spongy) bone
53
why are osteons in compact bone aligned in the same direction?
to increase unidirectional strength
54
what is in haversian canals in compact bone?
blood vessels
55
what surrounds the haversian canal?
sheets of bone - concentric lamellae
56
where are osteocytes in compact bone?
in lacunae between concentric lamellae
57
osteocytes in compact bone communicate with each other via what?
canaliculi
58
- 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 __________)
form interstitial lamellae (between concentric lamellae)
59
what is the lamellar bone that surrounds the outside of the bone called?
circumferential lamellae
60
blood vessels from the periosteum enter through ________ and communicate with the vessels in the ______
- enter through Volkmann canals (perpendicular channels)
- haversian canal
61
trabeculae of cancellous bone is arranged haphazardly to form a network of interconnecting struts designed to provide what?
maximum strength for minimum mass
62
what do spaces between trabeculae in spongy bone contain?
bone marrow
63
where do osteocytes in cancellous bone lie?
lie in lacunar near the surface of the trabeculae (instead of between lamellae like in compact bone)
64
how are trabeculae orientated in cancellous bone?
along the lines of stress
65
what do yellow and red bone marrow contain?
yellow — adipocytes
red — haematopoietic stem cells
66
spongy bone contains no ____ or _____ unlike compact bone
Volkmann’s or Haversian canals
67
a sheet of bone that encircles an osteon is termed a what?
concentric lamellae
68
fibrocartilage increases size by what?
interstitial growth
69
