X A&P - Chp 8 - The Muscular System Flashcards
3 types of Muscle
Smooth
Cardiac
Skeletal
Smooth muscle
- walls of hollow body organs
- contracts involuntarily
- produces peristalsis
- can regulate diameter of an opening
- tapered at end
- single central nucleus
- no striations
Cardiac Muscle
- hearts wall
- creates pulsing action of heart
- Striated
- one nucleus per cell
- branching interconnections
- electric impulse travel rapidly through them
Intercalated discs
membrane between cardiac muscle cells (show as dark lines) allow electric impulses
Skeletal Muscle
- appear heavily striated
- long and cylindrical cells
- multiple nuclei per cell
- attached to bone and produce movement at joints
Skeletal Muscle ? % of body weight
40%
largest amount of body’s muscle tissue
Primary functions of skeletal muscles
- movement of skeleton
- Maintenance of posture
- Generation of heat (shivering)
Fascilcles
bunch of muscle fibers
Endomysium
connective tissue around individual fibers in fascicles
Perimysium
connective tissue encasing each fascicle
Epimysium
connective tissue encasing entire muscle
innermost layer of the Deep Fascia
Neuromuscular Junction
point where nerve contacts muscle cell
Acetylcholine (ACh)
a nuerotransmitter
Motor end plate
muscle cell’s receiving membrane
?????
Difference btwn Motor end plate and Neuromuscular Junction
Action Potential
spreading wave of electric current.
Contractility
muscle fiber’s capacity to undergo shortening, becoming thicker.
Proteins that make up muscle fiber
Actin - thin and light
Myosin - thick and dark
Sarcomere
contracting sub-unit of skeletal muscle
What triggers Myosin heads to move?
ATP
What needed to allow crossbridge to form between actin and myosin
Calcium
Calcium stored where
Sarcoplasmic Reticulum
Troponin and Tropomyosin cover sites on actin where cross bridges form until
Calcium attaches to troponin and they move aside allowing access to bonding sties
Calcium released into cytoplasm when
muscle is stimulated by nerve cell
Steps of muscle contraction
1) ACh released from nueron to synaptic cleft at NMJ
2) ACh binds to muscles motor end plate and produces action potential
3) Action Potential travels to SReticulum
4) SR releases Ca into cytoplasm
5) Ca shifts troponin and tropomyosin so binding sites on actin are exposed
6) Myosin heads bond to Actin forming cross-bridges
7) using stored energy, Myosin heads pull filaments together within sarcomere (cell shortens)
8) New ATP is used to detach myosin heads and move back for another stroke
9) Muscle relaxes when stimulation ends and Ca pumped back into SR.
Myoglobin
stores O2 in muscles, similar to hemoglobin in blood
Glocogen
storage form of glucose
Types of Muscle Contractions
Isotonic
Isometric
Isotonic contractoin
tension remains the same
movement