2/3- Muscular System (Exam 1) Flashcards
What is fascicules?
Tissue in muscle cells
What is epimysium?
CT holding muscle together
What is perimysium?
Bonds fascicules together
What is endomysium?
Delicate CT wraps individual muscle cells
Blood vessel supply
Has capillaries
Nerve fibers that connect to muscle cells
Satellite cells
Why do muscles cells have satellite cells?
Stem cells
There just in case muscle cells need to be replaced
What does CT have that has tensile strength and in epimysium and emdomysium?
Collagen
What are tendons?
Muscle to bone
Formed by CT at the end of the muscle
Rope like structure
Super strong
Attaches to skeleton
Made of collagen
What is periosteum?
CT sheath around bone
Tendon anchors on this
What is a flat muscle with sheet like tendon called?
Aponeurosis
What is the point of muscle attachment that doesn’t move when contracted called?
Origin
- more proximal for arms and legs
What is the point of muscle attachment that does move when contracted?
Insertion
- more distal in arms and legs
What are the 3 strange aspects of skeletal muscle cells?
1) BIG
- huge diameter
- muscle cells are as long as muscles it’s in
2) multinucleate
- many nuclei
- has genetic code all over
3) striated
- alternating dark and light lines
What are the dark lines in a striation called?
A bands
What are the light lines in a striation called?
I bands
What are myoblasts?
Stem cells that are in embryo
Have one nucleus each
Fuse during development and fuse nuclei together
Live in delicate tissue in muscle cells
Becomes satellite cells when stored
What are the 3 basic kinds of skeletal muscle cells?
1) fast fibers or white fibers
2) slow fibers or red fibers
3) intermediate fibers
What are fast or white fibers?
Majority
Contract quickly
Large diameter
Produce powerful contractions
Fatigue easily
What are slow or red fibers?
Take 3 times longer to contract
Half the diameter of fast fibers
Resist fatigue
Red fibers
What is the slow or red fibers red?
Pigmented protein Myoglobin (carries O2)
What are intermediate fibers?
Intermediate diameter
Fast contraction (not as fast fibers)
Resist fatigue (not as resistant as slow fibers)
Pale in color
What is white muscle?
Muscles that are dominated by fast fibers
Ex: hand, muscles moving eyeballs
What are red muscle?
Muscles dominated by red fibers
Ex: legs, back
Do muscle contractions begin with nerve impulses?
Yes
What is a neuromuscular junction or motor end plate?
Space/ synapse between axon terminal branch of somatic motor neuron and muscle cell
What is a somatic motor neuron?
Motor nerve connected to muscle
What is Acetylene (Ach)?
Only neurotransmitter used when nerve impulse goes down an axon and hits axon terminal branches and across synaptic cleft and depolarizers muscle (shortens muscle)
What is a twitch?
When a muscle receives one nerve impulse
Muscle shortens and returns to normal length quickly
All muscle action is based on this
What are the 2 parts of a twitch and explain
1) Contraction Phase- tension is building
2) Relaxing Phase- pass peak of tension and relaxing
What is a latent period?
Short delay between stimulus and contraction
What is a wave summation or summation?
Several nerve impulses after the other before muscle straightened out and gets even shorter
What is a tetanus or tetany?
Nerve impulses so fast you see no or little relaxation period and becomes a smooth contraction
What is a complete tetanus?
No visible relaxation
How muscles operate
What is incomplete tetanus?
Slight relaxation
What is a motor unit?
Thing inside muscle that makes it work
Always active
100s cells working and have tension but not enough to contract
Keep working until they fatigue
Recruitment
The tension made by muscle units and make the muscle rubbery is called?
Muscle tone or Tonus
What is recruitment?
Control strength of muscle
Start with small and few motor units and recruit additional that are larger for the tension needed
What is resistance?
Muscle working against some force
Either isometric or isotonic
What is isotonic?
Muscle length is changing
What is concentric isotonic contraction?
Classic kind
Muscle gets shorter
What is eccentric isotonic contraction?
Muscle is contracting but getting longer because something else is pulling on it and stretching it
Gently letting something down
Less tension
What is isometric?
Length of muscle doesn’t change
Trying to get shorter but can’t
What is a sacromere?
Basic functional unit of every muscle cell
Makes muscle cell work
Several proteins
What are the 4 proteins in sarcomeres?
1) Actin
2) myosin
- give movement
3) Tropomyosin
4) Troponin
- on/ off switch
Shorten muscle when you want and stop it when you want
What are Actin and myosin?
Microfilaments
Actin- thin microfilament
Myosin- thick microfilament
What are long chains of sarcomeres in muscle cells called?
Myofibrils
