Physiology Flashcards
three types of muscle
skeletal, cardiac, smooth
striated muscle
cardiac and skeletal
unstriated muscle
smooth muscle
how is striation visualised under a microscope
alternating dark bands (myosin) and light bands (actin)
voluntary muscles innervated by somatic nervous system
skeletal
involuntary muscles innervated by ANS
cardiac and smooth
where and when is calcium released from
lateral sacs of sarcoplasmic reticulum when surface action potential spreads down transverse t tubules
what is a motor unit
single alpha motor neuron and all the skeletal muscle fibres it innervates
do muscles which serve for fine movement have more or fewer fibres per motor unit?
fewer
levels of muscle organisation
muscle - muscle fibre - myofibril - sarcomere
light appearance in myofibril
actin
dark appearance in myofibril
myosin
what are the functional units of muscle
sarcomeres
what is the functional unit of any organ
the smallest component capable of performing all the functions of that organ
What is an A band
thick filaments along with portions of thin filaments that overlap in both ends of thick filaments
What is an H zone
lighter area within middle of A band where thin filaments don’t reach
What is an M line
extends vertically down middle of A band within the centre of H zone
What is an I band
consists of remaining portion of thin filaments that do not project in A band
what produces muscle tension
sliding of actin on myosin
factors determining gradation of skeletal muscle
number of muscle fibres contracting within the muscle and tension developed by each contracting muscle fibre
Prolonged muscle contraction resulting from many APs in a short time
tetanus
can cardiac muscle be tetanised?
no
name for a single contraction in skeletal muscle
twitch
two types of skeletal muscle contraction
isotonic and isometric
what is isotonic contraction used for
body movements and moving objects
muscle tension constant when muscle length changes
what is isometric contraction used for
supporting objects in fixed positions and maintaining body posture
muscle tension develops at constant muscle length
Knee jerk
spinal segment L3/4
femoral nerve
Ankle Jerk
S1/2
tibial nerve
Biceps jerk
C5/6
musculocutaneous nerve
brachioradialis jerk
C5/6
radial nerve
Triceps jerk
C6/7
radial nerve
what are the sensory receptors for the stretch reflex
muscle spindles/intrafusal fibres
Type 1 fibres
slow oxidative
prolonged relatively low-work aerobic activities - posture, walking
Type 2a fibres
fast oxidative
aerobic and anaerobic metabolism and useful in prolonged relatively moderate work activities - jogging
Type 2x fibres
fast glycolytic
anaerobic metabolism, used for short term high intensity activities like jumping
stages of synaptic transmission
synthesis storage release receptor activation transmitter inactivation
neurotransmitter at NMJ
acetylcholine
end plate potential (epp)
depolarisation of skeletal muscle fibres as a result of neurotransmitter binding to postsynaptic membrane in NMJ
electrical response to one quantum of transmitter
miniature end plate potential (mepp)
auto-antibodies in neuromyotonia (Isaac’s syndrome)
voltage activated potassium channels in the motor neurone
auto-antibodies in Lambert-Eaton myesthenic syndrome
voltage activated calcium channels in motor neurone terminal
auto-antibodies in myasthenia Gravis
nicotinic ACh receptors in the endplate
drugs for neuromyotonia
anti-convulsants
drugs for Lambert Eaton syndrome
anticholinesterases and potassium channel blockers
drugs for myasthenia gravis
anticholinesterases in diagnosis and pyridostigimine for long term treatment along with immunosuppressants
three main types of joint
fibrous (synarthrosis)
cartilaginous (amphiarthrosis)
synovial (diarthrosis)
why does synovial fluid have a high viscosity?
due to presence of hyaluronic acid
functions of synovial fluid (5)
lubrication
facilitates joint movement
minimises wear and tear
aids in nutrition of articular cartilage
supplies chondrocytes with O2 and nutrients and removes CO2 and waste
structure of ECM of articular cartilage
water, collagen and proteoglycans
function of water in ECM
maintains resiliency of tissue and contributes to nutrition and lubrication system
function of collagen in ECM
tensile stiffness and strength
function of proteoglycan in ECM
responsible for compressive properties associated with load bearing
how do chondrocytes receive nutrients and oxygen?
via synovial fluid because articular cartilage is avascular
catabolic factors of cartilage matrix turnover
stimulate proteolytic enzymes and inhibit proteoglycan synthesis e.g. TNFa and IL1
anabolic factors of cartilage matrix turnover
stimulate proteoglycan synthesis and counteract effects of IL1 e.g. TGFb and IGF1
markers of cartilage breakdown
serum and synovial keratin sulphate and type 2 collagen
three types of pain
nociceptive
inflammatory
pathological
adaptive pain
nociceptive
inflammatory
maladaptive pain
pathological
pain responsible for withdrawal reflex
nociceptive
pain which is activated by the immune system
inflammatory
pain which results from abnormal nervous system function
pathological
subtypes of nociceptor
A-delta fibres
C fibres
A-delta fibres
thinly myelinated
mechanical/thermal nociceptors
mediate fast/first pain
C fibres
unmyelinated
second or slow pain
subset of C fibres
peptidergic polymodal nociceptors
afferent and efferent
function of afferent C fibres
transmit nociceptive information from CNS via release of glutamate and peptides within dorsal horn
function of efferent C fibres
release pro-inflammatory mediators from peripheral terminals - neurogenic inflammation
Two peptides involved in neurogenic inflammation
SP and CGRP
function of SP
causes vasodilation and extravastion of plasma proteins and a release of histamine from mast cells and sensitisation of surrounding nociceptors
function of CGRP
induces vasodilation
primary neurotransmitter in dorsal horn
glutamate
in which laminae of Rexed do nociceptive c and a-delta fibres terminate
I and II
Cells receiving A-beta fibres are
proprioceptive
two major nociceptive tracts
spinothalamic and spinoreticular tracts
what does spinothalamic tract detect
where is the pain coming from and how bad is it
what does spinoreticular tract detect
autonomic responses to pain - emotional side, how bad is it etc.
largely transmits slow C fibre pain
