9 - skeletal muscle, cartilage and bone histology Flashcards
functions of skeletal muscle
- moves and stabilises the skeleton
- forms sphincters in digestive and urinary tracts
- involved in respiration
name 4 characteristics of skeletal muscle
- long, cylindrical cells
- striated
- multiple, peripherally located nuclei
- innervated by somatic nervous system
what is endomysium?
connective tissue layer surrounding a single muscle fibre
what is a fascicle?
bundle of muscle fibres
what is the name given to the connective tissue layer surrounding a fascicle?
perimysium
what is a group of fascicles called?
muscle
what is epimysium?
connective tissue layer surrounding a muscle
describe slow twitch muscle fibres
- 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
describe fast twitch fibres
- 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
type IIa vs IIb muscle fibres
IIa — intermediate fast twitch, use both aerobic and anaerobic respiration
IIb — use only anaerobic
who is most likely to have type I/II fibres?
I — marathon runners
II — sprinters, jumpers, weight lifters
all the fibres of a single ______ are of the same type
motor unit (an individual motor neuron and all the muscle fibres that it innervates)
what detect fibre length?
sensory stretch receptors = muscle spindle
how does muscle spindle lie in relation to muscle fibres?
in parallel
what does muscle spindle consist of?
- 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
what happens when a muscle fibre is stretched?
receptors stretched — reflex — muscle shortens
what kind of innervation do spindle cells also receive? function?
motor innervation from CNS by gamma neurons — regulates sensitivity of receptor
what are the functions of cartilage?
- framework in resp tract
- shock absorption and facilitation of joint movement
- covers articular surfaces
- development of long bones
cartilage consist of what cartilage cells suspended in an ECM?
- chondrogenic cells — stem cells : differentiate into chondroblasts
- chondroblasts — immature cells
- chondrocytes — mature cells : maintain matrix
most cartilage is surrounded by what?
perichondrium = connective tissue layer
cartilage is ___ so gains nutrients via diffusion
avascular
what are the 3 types of cartilage?
hyaline, elastic and fibrous
what are the 2 types of cartilage growth?
- appositional — occurs just deep to the perichondrium
- interstitial — occurs within actual tissue of cartilage - in areas with no perichondrium. occurs by mitosis of chondrocytes
where is hyaline cartilage found?
= 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
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
why does the ECM in hyaline cartilage appear smooth and glassy?
because the fibres and ground substance are of similar refractive properties
what type collagen fibres does hyaline cartilage contain?
type II collagen fibres