muscular system Flashcards
what are the 3 muscle type?
Smooth muscle cell
skeletal muscle
cardiac muscle
What is another name for skeletal muscle?
Strated (stripes) muscles or voluntary muscles
What is the structure of the skeletal muscle attachment?
Attached to bones by tendons (ligaments attach bone to bone
Why do muscle bone come in pair?
To move in opposite directions
one contracts and the other relaxes.
what does the skeletal muscle require to contract?
It requires nervous impulse to contract
if it’s from the spinal cord it’s a reflex.
what is the name of the muscle fiber cells?
muscle fibers (cells) Multi-nucleated.
what fibers bundle are muscle made up of? why?
Muscles are a bundle of parallel fibers to increase strength in one direction-unlike the branching fibers of the heart.
What is each cell of the skeletal muscle covered in?
Fascia aka connective tissue
what are muscle fibers (myofibrils) made up of?
myofibrils are made up of a series of small sections called sarcomeres.
what makes up each sarcomere?
Each sarcomere is made up of thin myofilaments(actin) and thick myofilaments (myosin)
What surrounds myofibrils (muscle cells)?
nuclei from stem cells
what happens as a result of the thin(actin) myofilaments extension?
thin extend beyond thick it creates a lighter area.
What happens as a result of the thick( myosin) myofilaments extension?
thick and thin together they create darker areas.
What forms as an alteration of the light and dark areas?
creates visible lines perpendicular to the muscle and are the striations.
what is the all or none theory for the muscular system?
they come together or don’t come at all
What happens when the actin and myosin slide together? what happens to the sarcomere?
this is a contracdation- sarcomere gets shorter.
What happens when the actin and myosin slide away from each other? what happens to the sarcomere?
this is relaxation- sarcomere gets longer
What is actin attached to?
actin is attached t the Z-line to the sarcomeres on either side
What is the lighter area of sarcomere called?
I band
What is the name of the dark area between the I bands?
A band
What is the H zone?
when the sarcomere is relaxed is called the H zone.
What are the characteristics of the skeletal muscle cell?
- ) Voluntary
- ) must have nervous innervation to contract
- )contraction controlled by cerebral motor cortex
- )Nerve connects to muscle at the motor endplate
What are the characteristics of the cardiac muscle cell?
- ) Heart muscle branching
- )Striated
- )Will contract without nervous innervation
- )Pacemaker SA node
- )Multinuclinated
- ) Intercalated discs
- )Pumps blood
- )Involuntary
Where are smooth muscles found?
- )Aorta
- )veins
- )the urinary bladder
- )respiratory tract
- )arrector pili of skin
- )the ciliary muscle distance
- )iris of the eye
- )glomeruli of the kidneys
What are characteristic of the smooth muscle cell?
- ) Nonstriated
- )Single nucleus
- )Spindle-shaped
- )Involuntary
- )Must have nervous innervation o contract
- ) from the brain stem.
What are the steps for muscle contraction?
1.)Motor Nerve
Impulse: Action potentials arrive at the synaptic end bulb the axon terminal, ole structure= neuromuscular junction
2.) Calcium ions diffuse into synaptic bulbs through voltage-gated calcium channels.
3.) Acetylcholine released by vesicles through exocytosis into the synaptic cleft.
4.)Then it binds to ACh receptors on the motor endplate (cell membrane of muscle across from the axon terminal)
5.) Na+ ion enters through these ion channels (and K+ leaves, just like in neuron, repolarization)
6.) Na+ entrance sets up an action potential on the sarcolemma. The sarcolemma is depolarized.
Where does muscle contraction occur?
Happens on multiple muscle fibers from one neuron with multiple terminal button.
How is ACh destroyed? What happens to the stimulus?
ACh is destroyed by AchEsterase or diffuses throughout the synaptic cleft. ACh also diffuses away.Stimulus stops when ACh is destroyed.
What covers up actin?
Actin is covered by a strip of tropomyosin with troponin molecules attached.
What covers up myosin?
movable myosin heads to move the actin.