physiology Flashcards
functions of skeletal muscle
- posture
- movement
- respiratory movement
- heat production
- whole body metabolism
is smooth muscle striated
no
is skeletal muscle neurogenic or myogenic
neurogenic
is there a neuromuscular junction in skeletal or cardiac muscle
skeletal
what is the transmitter at a neuromuscular junction
acetylcholine
what is a motor unit
it encompasses all the muscle fibres innervated by a single alpha motor neuron
what is the sarcomere
the functional unit of skeletal muscle
what are the four zones in sarcomere
A band
H zone
M line
I band
is actin thin or thick
thin
is myocin thin or thick
thick
in sliding filament theory, what is force generation dependant on
ATP-dependant interaction between myosin and actin
what is excitation contraction coupling
the process whereby the surface action potential results in activation of the contractile structures of the muscle fibre
why is there no cross bridge binding when the muscle fibre is relaxed
because the cross-bridge binding on the actin is physically covered by the troponin-tropomyosin complex
what happens when muscle fibre is excited
calcium binds with troponin pulling troponin-tropomyosin complex aside to expose cross bridge binding site - cross bridge binding occurs
where is Ca++ derived from
sarcoplasmic reticulum in skeletal muscle
what is ATP needed for during relaxation
to release cross bridges and to pump calcium back into the sarcoplasmic reticulum
is a single twitch useful
no need a double twitch
when is maximal tetanic contraction achieved
when the muscle is at its optimal length before the onset of contraction
isotonic muscle contraction
muscle tension remains constant as the muscle length changes
isometric muscle contraction
muscle tension develops at constant muscle length
what are some metabolic pathways that supply ATP in muscle fibre
- transfer of high energy phosphate from creatine phosphate to ADP
- oxidative phosphorylation
- glycolysis
what are slow oxidative type 1 fibres used for
prolonged relatively low work aerobic activities
three types of joints
synovial
fibrous
cartilaginous
fibrous joint
- bones united by fibrous tissue
- doesnt allow any movement
cartilaginous joint
allow limited movement
-intervertebral discs
synovial joints
- separated by a cavity and united by a fibrous capsule
- knee
what are simple and compound synovial joints
simple - one pair of articular surfaces
compound - more than one pair of articular surface
what is joint lubrication provided by
- cartilage interstitial fluid
- synovium
- synovium-derived lubrcin
functions of synovial fluid
- lubricates joint
- facilitates joint movements
- helps minimise wear and tear of joints
- aids in nutrition of articular cartilage
- supplies chondrocytes with O2 and nutrients and removes CO2 and waste products
does synovial fluid have high or low viscosity
high
what is rapid joint movement associated with in terms of viscosity and elasticity
decreased viscosity and increased elasticity
viscosity of inflammatory synovial fluid, high or low
low
functions of articular cartilage
- low friction lubrication
- distributes contact pressure to subchodral bone
4 zones of cartilage
- superficial zone
- middle zone
- deep zone
- calcified bone
what are the mechanical properties of the cartilage
water
collagen
proteoglycan
what is the extracellular matrix of the articular cartilage synthesised, organised, degraded and maintained by
chondrocytes
what can happen if the rate of ECM degradation exceeds the rate of its synthesis
joint disease
what are the catabolic factors of cartilage matrix turnover and what do they do
tumour necrosis factor (TNFalpha)
IL-1
they stimulate proteolytic enzymes and inhibit proteoglycan synthesis
what are the anabolic factors of cartilage matrix turnover and what do they do
Stimulate proteoglycan synthesis and counteract effects of IL-1
Tumour growth factor (TGF)-β
Insulin-like growth factor (IGF)-1
definition of pain
An unpleasant sensory and emotional experience, associated with actual tissue damage or described in terms of such damage
what are the four processes in the physiology of pain
- transduction
- transmission
- modulation
- perception
what is tranduction
translation of noxious stimulus into electrical activity at the peripheral nociceptor
what is transmission
propagation of pain signal as nerve impulses through the nervous system
what is modulation
modification/hindering of pain transmission in the nervous system e.g. by inhibitory neurotransmitters like endogenous opioids
what is perception
Conscious experience of pain. Causes physiological and behavioural responses
what does pain begin with
the activation of nociceptors
what are nociceptors
they are specific primary sensory afferent neurones normally activated by intense noxious stimuli Nociceptors are first order neurones that relay information to second order neurones in the CNS by chemical synaptic transmission
what do the second order neurons do
ascent the spinal cord in the anterolateral system (terminate in the thalamus)
what does the anterolateral system compose of
- the spinothalamic tract
- the spinoreticular tract
what is the STT involved in
pain perception
what is the SRT involved in
autonomic responses to pain, arousal, emotional responses, fear of pain
where is the sensory information relayed to from the thalamus
via third order neurons to the primary sensory cortex
what are the different types of fibres in nociceptors
Adelta fibres
C fibres
what are A delta fibres
are mechanical/thermal nociceptors that are thinly myelinated (conduction velocity of 6.0-30.0 ms-1 ) - respond to noxious mechanical and thermal stimuli. Mediate ‘first’, or fast, pain
what are C fibres
are nociceptors that are unmyelinated (conduction velocity of 0.5-2.0 ms-1) – collectively they respond to all noxious stimuli (e.g. they are polymodal). Mediate ‘second’, or slow, pain
what are the 4 ways to classify pain
- mechanisms
- time course
- severity
- source of origin
what is nociceptive pain usually in response to
injury of stimulus by noxious stimuli
only provoked by intense stimulation of nociceptors
what is neuropathic pain caused by
damage to neural tissue
examples of dysfunctional pain
IBS, tension headache, interstitial cystitis
what is referred pain caused by
caused by convergence of nociceptive visceral and skin afferents upon the same spinothalamic neurons at the same spinal level
