A&P Lecture Exam 4 Flashcards
Myo, Mys, Sarco
prefixes meaning muscles.
Skeletal muscle
Attached to bones, has striations, voluntary (doesn’t contract till brain tells it to). Responsible for body motility, adapts to environment and tires out quickly.
Cardiac muscle
Walls of the heart, has striations, involuntary (contracts all the time, heart beats on its own without nervous system stimulating it. Beats faster when under serious exercise and slows down normal when resting.
Smooth muscle
Walls of the hollow organs, no striations, involuntary (lungs breathe on their own, digest itself). Visceral
Excitability
Responsiveness. Ability for cell to receive and respond to stimulus by changing the membrane potential (usually stimulus from nervous system)
Contractility
Contract/getting shorter. Ability to shorten when stimulated, sets muscle apart from other tissue types.
Extensibility
Extends and stretches (gets larger). Muscle cells shorten when contracted, and can be stretched when relaxed.
Elasticity
Recoil and resume its resting length after stretching.
What are the 5 functions of muscles.
- Movement
- Maintain posture
- Stabilizes joints
- Generate heat: when contracting, plays a role in maintaining normal body temp.
5.Protect organs, form valves, control pupil size, cause “goose bumps.”
What are skeletal muscles served by?
Served by one artery, one nerve, and one more veins. This is how blood gets to muscle to heal, notorious, waste products out, oxygen to muscle to form ATP.
What are the 3 connective tissue sheaths?
- Epimysium
- Perimysium
- Endomysium
Epimysium
Fascicles wrapped together to make one muscle. The most superficial layer, surrounds the whole muscle.
Perimysium
each skeletal muscle is grouped into fascicles (bundles). Perimysium surrounds these bundles as a layer of dense irregular connective tissue, around the muscles.
Endomysium
Sheath of connective tissue surrounding each muscle fiber (1 each). Consists of areolar connective tissue.
Insertion
Muscle attaches to moveable bone in joint. Distal
Origin
Site where bone and muscles attach, bu do not move. Proximal
Direct attachment
Epimysium of muscle fused to periosteum of bone. (don’t need tendon to connect
Indirect attachment
muscles connective tissue wrap extends beyond muscle as tendon. Tendon anchors the muscle to connective tissue of bone to fascicles of muscle.
Sarcolemma
muscle fibers plasma membrane, able to conduct electrical impulses.
Sarcoplasm
Calcium is released here. “cytoplasm” of muscle fibers. Contains large amounts of glycosomes and myoglobin.
Myofibrils
single muscle fibers stuffed with these, made of proteins arranged in specific patterns. Makes up 80% volume of muscle fibers, it’s what exhibits striations.
Sarcoplasmic reticulum
draped around myofibrils (endoplasmic reticulum- but in muscle fibers) releases calcium.
Sarcomeres
Pattern that myofibril are arranged in and how proteins line up (myosin and actin).
H Zone
thick filaments only, middle of sarcomere
M Line
thick filaments linked by accessory proteins (myosin)
Z Discs
A Band
contains actin and myosin, (thick and thin filaments overlap)
I Band
only actin protein present (thin filaments)