Muscular system Flashcards
When do you use muscles
All the time
Types of muscle tissue
skeletal, cardiac and smooth
The main function of the muscle system
Movement of the body, maintenance of posture, respiration, production of body heat, communication, constriction of organs and vessels, contractions of the heart
Skeletal muscle
long, cylindrical muscles attached to the bones that allow for voluntary and involuntary movement
Smooth muscle
Spindle-shaped muscles that moves food through the digestive track, empties the bladder, regulates blood vessel diameter and contracts glands
Cardiac muscle
Branched muscles of the heart that contracts to pump blood
Contractility
the muscle’s ability to forcefully shorten or passively lengthen
Skeletal muscle contraction
movement
Cardiac muscle contraction
increases pressure in heart
Smooth muscle contraction
increases organ pressure
Excitability
muscles responding to stimulus
Skeletal muscle excitability
stimulus to contract comes from nerves
Smooth and cardiac muscle excitability
respond to hormonal and neural signals, but also contract spontaneously
Extensibility
stretching a muscle beyond it’s normal resting length without breaking and being able to function
Elasticity
muscle recoiling
Striated muscle
another name for skeletal muscle because of transverse bands that can be seen under a microscope
What is skeletal muscle made of
skeletal muscle tissue, nervous tissue, connective tissue, and adipose tissue
muscle fiber
a muscle cell
Layers of connective tissue
epimysium, perimysium, endomysium
Epimysium
connective tissue sheath made of protein fibers that surround the muscle that separate and connect it to the skin and other organs
perimysium
connective tissue that serves as a passage way for blood vessels and nerves, and subdivies the muscle
fascicles
bundles of muscle fibers
endomysium
delicate layer of connective tissue that separates each individual muscle fiber in the fascicles
Tendons
ends of connective tissues that connect the muscle to bone
Sarcolemma
cell membrane of muscle fibers
transverse tubules (t tubules)
carry electrical impulses into the center of the muscle fiber
Sarcoplasmic reticulum
specialized smooth ER that stores Ca+.
Ca+ function
the release of Ca+ charges the triad and causes contraction
sarcoplasm
cytoplasm of muscle fiber
Myofibrils
bundles of protein filaments that extend the length of the muscle fiber and cause shortening during contraction
Myofilaments
protein thread that help myofibrils
Actin myofilaments
thin filaments
myosin myofilaments
thick filaments
sarcomeres
functional units of skeletal muscles that are made of myofilaments and join to for myofibrils
Z disks
anchor for myofilaments
I bands
two lighter-staining regions that extend to the ends of the myosin myofilaments and only contain actin myofilaments
A bands
darker-staining band that contains both actin and myosin myofilaments
H zone
center of an A band that is only made of myosin myofilaments
M line
protein filaments that hold the myosin myofilaments in place in the center of the H zone
Actin
an attachment site on the actin myofilaments of the myosin myofilaments during contraction
tropomyosin
covers for the attachment sites on the actin that must be moved for muscle contraction
Troponin
anchors the troponin to the actin
prevents tropomyosin from uncovering
binds to Ca 2+
myosin molecules heads function
1) heads biind to active sites on actin molecules to contract
2) heads are attached to rod portion that bends and straightens during contraction
3) heads break down ATP for energy
Neuromuscular junction (synapse)
point of contact between nerve and muscle fiber
Acetylcholine
opens ligand-gated ion channels
Acetylcholine
opens ligand-gated ion channels
ligand
molecule that binds to a macromolecule
Sliding filament model
used to explain how actin and myosin myofilaments slide over each other during muscle contraction
resting membrane potential
charge difference across a resting cell
Action potential of a muscle cell
- when stimulated Na+ channels open and makes the cell positive
- Action potential is triggerd
- Depolarization phase
- permeability changes causes repolarization
5.Na + channels close and K+ channels open so K + can leave - resting membrane potential is restored by sodium-potassium pump
Neurotransmitter junction actions
- action potential opens the Ca2+ channel and diffuse into the axon terminal
- Ca2+ causes the secretion of vesicles
- Acetylcholine is released
- Acetylcholine bind to Na+ channels in the muscle membrane
- Na+ enters muscle and causes action potential in muscle
Muscle contraction
- action potential from Na + travels along sarcolemma and t tubule
- t tubules wrap around sarcomeres and carry action potentials to Ca 2+ channels
- Ca 2+ channels open and diffuse into the sarcoplasmic reticulum then to the sarcoplasm
- Ca2+ binds to troponin
- Troponin causes tropomyosin to move
- myosin heads bind to exposed actin
- ATP is broken down to move myosin heads
Myosin head movement(cross-bridge movement)
- myosin attaching to actin forms cross-bridges
- triggers rapid movement of myosin heads
- myosin myofilament is pulled towards the H zone
- Myofilaments slide
- ATP binds to the myosin head and detaches it
- Myosin head breaks down ATP into ADP
- Head returns to resting position
Recovery stroke
myosin head returning to resting position
Muscle relaxation
- Sodium-potassium pump transports Na+ out of the muscle fiber and K+ in
- recovery stroke
- ATP transports Ca2+ out
Slow-twitch
muscle fibers that contract slowly and are resistant to fatigue. They break down ATP slowly and have more mitochondria
Fast-twitch
muscle fiber that contract quickly and are prone to fatigue
Fast-twitch muscle fiber forms
Type 2a: rely on ATP production with and without O2
Type 2b: rely on ATP without O2
Separation of Slow and Fast twitch muscle fibers
Fast-twitch have very little dark-coloured myoglobin and slow-twitch are darker in colour, but humans have no clear separation of the two.
Effects of training
increase the size and capacity of both types of muscle fibres, increase vascularity, increases the number of motor units, improved metabolism, circulation, and number of capillaries
hypertrophie
muscles that increase in size with use
atrophie
muscles that decrease in size with use
autorhythmicly
the capacity of the smooth and cardiac muscles to generate action potentials spontaneously
intercalated disks
found in the gap of cardiac muscles, they allow action potentials to be conducted directly from cell to cell, so the cardiac muscle cells act as one unit
Cardiac muscle hormone
epinephrine
Retinaculum
dense regular connective tissue sheath holding down tendons in the wrist and ankle
origin
the fixed point of a muscle
insertion
end of the muscle attached to the bone that moves
belly
part of the muscle between the origin and insertion
agonist and antagonist muscles
when one muscle group is activated there is a counter muscle group also being activated
prime mover
the muscle that does the desired action
Muscle naming system
1 location
2 size
3 shape
4 orientation of fascicles
5 origin and insertion
6 number of heads
7 function
Fascicle arrangements
circular, convergent, parallel, pennate, fusiform
