Skeletal and smooth muscle Flashcards
(22 cards)
What is the name os a muscle cell membrnae?
Sarcolemma
What is the name of a muscle cell cytoplasm?
Sarcoplasm
Where are skeletal muscle fibres attached to?
Directly to bones - the periosteum
What happens to the origin and insertion during contraction?
Origin remains stationary
Insertion is attached to a bone and moved
Muscle fibres contain a lot of what?
Mitochondria
What 2 structures make up myofibrils?
Myosin (thick filament) and actin (thin filament)
What is the sliding filament theory?
Muscle contraction occurs when thick and thin filaments slide over each other
What needs to happen to calcium levels for muscles to relax?
the conc of Ca2+ needs to return to basal levels. This is achieved by active pumping of calcium into the SR and out of cells through the sarcolemma.
Where are calcium ions stored and released from?
Sarcoplasmic reticulum
What causes a muscle twitch?
Single stimulus contraction-relaxation sequence in a muscle fibre
What does an isotonic contraction cause?
Limb movement
What does the force of contraction depend on?
Number of cross-bridges
During muscle contraction, what is ATP required for?
Myosin ATPase and for calcium pumps
What is a high energy store unique to skeletal muscle?
Creatine
What is oxygen debt?
Amount of oxygen payment required after exercise in skeletal muscle to:
- replenish ATP stores
- Replenish creatine phosphate and myoglobin stores
- convert lactate back into pyruvate
Does myoglobin have a greater or lesser affinity for oxygen than haemoglobin?
Greater (shift to the left0
Why does the pH of skeletal muscle decreases during intense exercise?
Because pyruvate production also produces H+
Where is smooth muscle found in the body?
- GI tract (peristalsis)
- Uterus
- Bladder
- Eye
- Blood vessels
Compare smooth muscle structure to skeletal muscle
- similar amount of actin, less myosin
- Maximum contractile force similar to skeletal muscle
- Uses less energy than skeletal muscle to generate and maintain a given amount of force
- no neuromuscular junction
- no t-tubules
- no troponin
- less well-developed SR
- no sarcomeres
What allows direct communication between smooth muscle cells?
Gap junctions
Why does smooth muscle contract and relax much more slowly than cardiac and skeletal muscle?
Due to relative slow changes in sarcoplasmic [Ca]
What are the roles of smooth muscle in vessels?
- changes resistance to flow
- changes blood pressure
- changes perfusion
