DONE Muscles Flashcards
Striated muscle
Both skeletal + cardiac
Non-striated
Smooth muscle
Skeletal muscle
Myoglobin
Voluntary
Direct nerve-muscle communication
Cardiac muscle
Myoglobin
Involuntary
Indirect nerve-muscle communication
Smooth muscle
Myoglobin absent
Involuntary
No direct nerve-muscle communication
No sarcomeres/troponin
Myoglobin
Red protein, oxygen storing molecule, no affinity for CO2
Sarcolemma
Outer mem. of muscle cell
Sarcoplasm
Cytoplasm of muscle cell
Sarcosome
Mitochondrion
Sarcomere
Contraction unit in striated muscle
Sarcoplasmic reticulum
Smooth ER of muscle cell, calcium store
Structure + function of skeletal muscle
To contract
3 layers of CT = endomysium (loose, inner CT), perimysium (loose CT, surrounds fascicles), epimysium (outer, dense CT)
What colour are slow twitch fibres?
Red = lots of myoglobin, mitochondrion, cytochrome
Structure of cardiac muscle
Central nuclei (peripheral in skeletal) Sarcomere less developed than skeletal 1 contractile cell type (cardiomyocyte)
Smooth muscle structure
Spindle-shaped (fusiform)
Single, large, central nucleus
No sarcomeres
Slower contraction than skeletal
How do mature skeletal muscle cells repair?
Cells can’t divide
Regenerate via satellite cells = hyperplasia
How do mature cardiac muscle cells regenerate?
Can’t
Fibroblasts invade, lay down scar tissue
How do mature smooth muscle cells regenerate?
Retain mitotic activity
Tropomyosin
Bonds along actin, prevents myosin binding
Troponin-C
Calcium binding unit on troponin
Troponin-I
Binds to actin, holds actin-tropomyosin complex in place
Troponin-T
Pulls tropomyosin to expose myosin binding site
Creatine kinase
Catalyses ATP to ADP and Pi for energy for muscle contraction
Myasthenia gravis
Autoimmune disease
Antibodies block ACh receptor
Reduced synaptic transmissions = intermittent mucle weakness
Compartment syndrome
Limb divided into compartments by fascia
Trauma in 1 compartment = internal bleeding = pressure on blood vessels + nerves
SYMPTOMS = oedema, prolonged capillary refill time, paresthesia (pins + needles), deep + localised pain
Muscle tone
Tension in a muscle @ rest (healthy muscle never fully relaxed)
Muscular atrophy
Destruction > replacement (hypertrophy = opposite)
Muscular hypertrophy
New muscle fibrils + sarcomeres produced due to overstretching
Muscular atrophy
Disuse (bed rest), surgery (denervation of muscle), disease
Duchene muscular dystrophy
X-linked recessive
Dystrophin gene mutation
More calcium enters cell, taken up by mitochondria, H2O into mitochondria = burst, muscle cells burst (rhabdomyolysis), creatine kinase + myoglobin levels high in blood
Muscle cells replaced by adipose tissue
SYMPTOMS = stomach sticks out due to weak belly muscles, poor balance, thick lower leg muscles (mainly fat), sway back
Botulism toxin
Produced by Clostridium botulinum
Blocks neurotransmitter release @ motor end plate
Cause non-contractile skeletal muscle (flaccid paralysis)
Treat muscle spasms, botox
Organophosphate poisoning
Pesticides, inhibit ACh esterase (which stops signalling processes)
MUSCARINIC SYMPTOMS = SLUDGE (salivation, lacrimation, urination, defecation, GI cramp, emesis = vomiting)
NICOTINIC SYMPTOMS = MTWTF (muscle cramps, tachycardia, weakness, twitching, fasciulations)
Creatine kinase
Released into blood by damaged skeletal muscle and brain (from Intramuscular injections, a fall, rhabdomyolysis, muscular dystrophy)
