Chapter 10: Skeletal Muscle Flashcards
1
Q
Types of muscle
A
- Skeletal muscle: multinucleated, striated
- Cardiac muscle: striated
- Smooth muscle: non striated
2
Q
4 functions of muscle contraction
A
- Movement of bones
- Stabilization of positions
- Movement of substances
- Generation of heat: thermoregulation through shivering
3
Q
Movement of muscles
A
- Agonist: muscle responsible for contraction
- Antagonist: muscle responsible for stretching
- Synergy is when more than 1 muscle moves to produce movement
4
Q
Skeletal muscle structure
A
- Sacromere is the smallest functional unit and is composed of thick and thin filament
- Sacromere are positioned end to end which forms myofibrils
2a. Each myofibrils is surrounded via sacroplasmic reticulum (SR) - Sacrolemma wraps several myofibrils together to form muscle fiber
- Groups of many muscle fibers are bound to a faciculus
- Many fasciculi form muscle
5
Q
Thick vs thin filament
A
- Thick filament: made of myosin
- Thin filament: made of actin which is attached to troponin and tropomyosin
6
Q
Sections of a sacromere
A
- A band: where myosin is present
- M line: midline of myosin fibers
2a. Only thing that doesn’t shorten - Z line: anchors actin and is the boundaries for sacromere
- I band: area only with actin
- H zone: only myosin (within A band)
7
Q
Skeletal muscle contraction
A
- Neuromuscular junction is the synapse between a motor neuron and the motor end plate
- An action potential triggers release of Ach into NMJ where they bind to receptors on sarcolemma of muscle which opens ion channels and propagates AP
- AP moves into muscle via T tubules and it releases Ca2+
- Sliding filament theory occurs:
4a. Ca2+ binds troponin which pulls back tropomyosin to expose active side
4b. Myosin head binds to active site which forms cross bridge
4c. Myosin expels Pi and ADP and walks w actin in a power stroke which shortens sacromere
4d. New ATP attaches to myosin which causes myosin to be released from active site
4e. ATO hydrolyses into Pi and ADP which continues cycle
8
Q
How does Ca2+ go back into SR after contraction
A
- SERCA (Ca2+-ATPase pump): needs energy because Ca2+ is pumped against gradient
9
Q
Motor unit
A
- Has 2-2000 fibers
- What gets activated
10
Q
Creatine phosphate
A
- Transfers phosphate onto ADP and the phosphates system is used up quickly
- As phosphagen system is used up, glycogen-lactic acid system becomes dominant supplier of ATP
11
Q
Cori cycle
A
- Glycolysis produces lactate
- Lactate goes to liver and undergoes gluconeogenesis to be sent back as glucose
12
Q
3 types of muscle fiber types
A
- Slow oxidative (type 1): red (high myoglobin), high mitochondria, low glycogen, endurance
- Fast oxidative-glycolytic (type 2a): strength
- Fast glycolytic (type 2b): low myoglobin, low mitochondria, high glycogen, power
13
Q
Cardiac muscles
A
- Cardiomypcytes are seperated via intercalated discs (gap junctions) which allows fast depolarization
14
Q
Smooth muscle: single unit
A
- Visceral
- Connected by gap junctions spreading the action potential from a single neuron through a large group of cells and allows cells to contract as a single unit
15
Q
Smooth muscle: multi unit
A
- Attached to a neuron
