basics Flashcards
what are the features of smooth muscle?
involuntary
non-striatedw
what are the features of cardiac muscle?
involuntary
striatedw
what are the features of skeletal muscle?
voluntary
striated
what is found in both skeletal and cardiac muscle?
sacromeres
what is a sacromere?
unit of striated muscle that can contract by sliding filaments
where are the sacromeres in skeletal muscle found?
neuromuscular junctions (neurogenic)
where are the sacromeres in cardiac muscle found?
gap junctions (myogenic)
what is skeletal muscle arranged into and what does it contain?
motor units
muscle fibres supplied by single alpha neuron
less muscle fibres per motor unit is required for?
precision
more muscle fibres per motor unit is required for?
power
what causes muscle tension?
actin sliding over myosin
what are the stages of muscle tension?
- Ach from motor neuron
- AP across and down T-tubules
- triggers Ca2+ release from S.R
- cross-bridge formation -> muscle contraction
- ATP needed to power and release cross-bridges and pump Ca2+ back into S.R
in slower lifting what allows for greater contraction?
more time for myosin to bind
why do action potentials summate to give contraction if in a short time frame?
no relax time for Ca2+ reabsorption
in which type of muscle action potentials do not summate to give contraction, and why?
cardiac
due to refractory period
what is the refractory period?
the period of time after an action potential initiates - unable to initiate another action potential - usually 250ms
what is isotonic contraction?
constant tension as muscle length change
body movements, moving objects
what is isometric contractions?
tension develops at constant muscle length
supporting fixed objects, posture
where is ATP supplied from?
creatinine phosphate -> ADP
oxidative phosphorylation
glycolysis
what are the features of type I muscle fibres?
slow twitch
aerobic
walking
what are the features of type IIa muscle fibres?
fast twitch
aerobic and anaerobic
jogging
what are the features of type IIx muscle fibres?
fast glycolytic
anaerobic
jumping
what is the stretch reflex?
muscle spindles are the sensory receptors (in belly of muscle)
what is the stretch reflex supplied by?
gamma motor neurons
where is the synovial membrane found?
vascular connective tissue
what does the synovial membrane contain?
fibroblasts
synovial fluid
what does synovial fluid do?
lubricates
supplies chondrocytes with oxygen
removes CO2 and waste
what does clear synovial fluid indicate?
nothing - normal
what does straw/yellow synovial fluid indicate?
inflammation
what does red synovial fluid indicate?
trauma
what does opaque synovial fluid indicate?
sepsis
what type of vascularity does articular (hyaline) cartilage have?
avascular
what does avascular mean?
lack of blood vessels
what are the characteristics of articular (hyaline) cartilage?
low friction gliding surface to prevent wear and tear
ECM
what is the ECM maintained by?
chondrocytes
what are the signs of disease in the ECM?
composition changes
rate of degradation > synthesis
markers - keratin sulphate/type 2 collagen in synovial fluid
what are the two types of cartilage matrix turnover?
anabolic
catabolic
what is anabolic cartilage matrix turnover?
proteoglycan synthesis (TGF-beta, IGF-1), IL-1 countered
what are the features of catabolic cellular matrix turnover?
stimulate proteolytic enzymes (IL-1, TNF-alpha)
what are nocicpetors?
sensory afferent (first-order neurons) activated by noxious stimuli
what is noxious stimuli?
pain
what are the subtypes of nociceptors?
Adelta fibres
C-fibres
what are the features of A-delta-fibres?
fast
mechanical/thermal, thinly myelinated
what are the features of C-fibres?
slow
all stimuli
unmyelinated
which fibres does the stimulus pass through first?
A- delta
what type of pain is primary pain/ do A-delta fibres feel?
stabbing
pricking
what type of pain is secondary pain/do C-fibres feel?
burning
throbbing
cramping
aching
what are the pathologies of the neuromuscular junctions?
neuromyotonia
Lambert-Eaton syndrome
myasthenia gravis
what causes neuromyotonia?
antibodies against potassium channels
what causes Lambert-Eaton syndrome?
antibodies against calcium channels
what causses myasthenia gravis?
IgG binding with acetylcholine on muscle cells
what are the investigations for myasthenia gravis?
anti-AChR IgG
what are the signs of myasthenia gravis?
droopy eyelid
sore swallowing
