Physiology Flashcards
physiological functions of skeletal muscle?
purposeful movement metabolism heat production posture maintenance respiratory movement
what causes the striation in skeletal muscle
dark myosin filaments
light actin filaments
what nervous system innervates skeletal muscles and what control are they under
somatic
voluntary
what is a motor unit
single alpha motor neuron and all of the skeletal muscle fibres it innervates
true/false - muscles doing finer tasks have more muscles per motor unit
false - they have less
what is a myofibril
part of skeletal muscle cell containing actin and myosin filaments arranged into sarcomeres
what is the Z line
line connecting two sarcomeres
what is the A band
thick myosin filaments with strands of actin filaments overlapping
what is the H zone
middle of A band where actin filaments do not reach
what is the M line
runs down middle of A band within centre of H zone
what is the I band
remaining portion of actin filaments that do not project into the A band
during skeletal muscle contraction, when is ATP required?
during contraction and relaxation of the myosin cross bridge
describe the events of skeletal muscle contraction within the sarcomere
AP is carried down T tubules and causes calcium release
calcium binds to tropomyosin to expose myosin cross bridge binding site. myosin cross bridge binds after ATP phosphorylation and contracts
AP disappears, calcium reuptake by SR and tropomyosin covers binding site. cross bridge detaches
what are the 2 factors skeletal muscle tension are dependent on
tension developed by each contracting fibre
number of muscle fibres contracting
what is motor unit recruitment
stronger contraction achieved by stimulation of many motor units
true/false - the more APs to a muscle, the stronger the contraction
true
what is tetanus (physiologically)
maximal sustained contraction without rest
maximal tetanic contraction is achieved when muscle is ___
at optimal length
what is isotonic contraction and examples
muscle tension is constant but length varies
body movement and moving objects
what is isometric contraction and examples
tension varies but length remains constant
posture, supporting objects in a fixed position
state the 3 main differences in skeletal muscles
enzyme pathways for ATP synthesis
activity of myosin ATPase
resistance to fatigue
describe slow oxidative muscle fibres and examples
low work, aerobic activities
posture maintenance, walking
describe fast oxidative muscle fibres and examples
aerobic and anaerobic metabolism, prolonged moderate work
jogging
describe fast glycolic muscle fibres and examples
anaerobic metabolism for short term, high intensity activities
jumping
describe the stretch reflex arc
muscle spindle activated by stretch
afferent neuron firing increased, synapse in cord
alpha motor neuron innervate stretched muscle to contract
what is a muscle spindle
sensory receptor for stretch reflex
what is an intrafusal fibre
muscle spindle
what is an extrafusal fibre
ordinary muscle fibres
what do gamma motor neurons do
adjust tension within the muscle spindle as the muscle itself contracts
what muscle and tendon is activated in the knee-jerk reflex
patellar tendon
contraction of quadriceps femoris
describe cartilagenous joint and examples
limited movement, united by cartilage
IV discs, pubic symphesis, costochondral joints, part of sacroiliac joint
describe fibrous joint and attachment
fibrous tissue, no movement
fissures in skull
what is the synovial membrane and what makes it up
inner aspect of fibrous capsule
vascular connective tissue and synovial cells producing synovial fluid
what is a simple synovial joint
one pair of articular surfaces
what is a complex synovial joint
more than one pair of articular surfaces
how does a joint remain stable
shape of joint
ligaments
synovial fluid
functions of synovial fluid
lubricates joint facilitates joint movement minimise wear/tear nutrition of articular cartilage supplies chondrocytes with o2 and nutrients and removes co2 and waste
true/false - synovial fluid is a static pool
false
true/false - rapid joint movement decreases fluid viscosity and increases elasticity
true
true/false - synovial fluid is rich in WBC
false - unless there is an inflammatory process or septic arthritis
what type of cartilage is articular cartilage
usually hyaline
describe layers of cartilage
articular surface with shallow superficial zone, deeper middle and deep zone
what is the ECM made up of in articular cartilage
mainly water
type II collagen
proteoglycan
true/false- water in ECM is evenly distributed
false
what maintains ECM
chondrocytes
what does collagen do in ECM
stiffness/stength
what does proteoglycan do in ECM
compressive properties
artricular cartilage is vascular/avascular
avascular - receives nutrient by synovial fluid
describe the balance of synthesis/degradation in normal and pathological joints
synthesis/degradation should be balanced, degradation exceeds synthesis in pathology
anabolic factors for cartilage matrix turnover
stimulates proteoglycan synthesis
TGF-B
IGF-1
catabolic factors for cartilage matrix turnover
inhibits proteoglycan synthesis
TNFa
IL-1
define pain
unpleasant sensory or emotional experience, associated with actual tissue damage or described in terms of such damage
describe the 4 physiological steps of pain processing
transduction of stimulant to nociceptor
transmission through CNS
modulation in nervous system
perception
describe nociceptor activation and what it does
sense noxious stimulus and run through afferent 1st order neuron to CNS
synapse with 2nd order in spinal cord to carry to thalmus
relay to thrid order to carry to primary sensory cortex
what is the function of the spinothalmic tract
pain perception
what is the function of the spinoreticular tract
response to pain, arousal, emotional response
what are Agamma fibres
thin myelinated nociceptor subtype to carry pain quickly
only mechanical and thermal
what are C fibres
unmyelinated nociceptor subtype mediating slower pain to all noxious stimuli
describe nociceptive pain
normal response to tissue injury
pain is adaptive
early warning
describe inflammatory pain
activation of immune system due to tissue injury/infection
heightened pain sensitivity and sensitivity to innoculous stimuli
adaptive
discourage movement
what is allodynia
heightened sensitivity to non-noxious stimuli
what is hyperalgesia
heightened pain sensitivity
describe neuropathic pain
pain due to neural tissue damage
simple analgesia not enough, pain is maladaptive
manage antidepressants/antiepileptics
neuropathies, phantom limb, central pain
describe dysfunctional pain
no identifyable damage/inflammation IBS, tension headache not fully understood simple analgesia not enough, pain is maladaptive manage antidepressants/antiepileptics
describe referred pain
pain felt in body not related to cause
convergence of nociceptive visceral/skin afferents on same spinal level
