Chapter 7: Muscular System Flashcards
Cardiac muscle
Heart- involuntary
Has 1 centrally located nuclei
Rich in mitochondria
Contract heart to propel blood through the body
Functions of muscles
- Movement
- Maintain posture
- Respiration
- Production of body heat
- Communication
- Heart beat
- Contraction of organs and vessels
Smooth muscle
Located in walls or hollow organs, blood vessels, and glands
Function: to compress organs, ducts, tubes, and so on.
Has less actin and myosin
1 centrally located nucleus
Involuntary
Skeletal muscle
Voluntary Attached to the bone Many nuclei per cell Longest type of muscle 40% of body weight
Abilities of the skeletal muscles
- Contractibility: shorten
- Excitability: respond to stimuli
- Extensibility: stretch
- Elasticity: recoil
Coverings of the skeletal muscle
Endomysium
Perimysium
Epimysium
Endomysium
Fine connective tissue sheath that surrounds each muscle fiber.
Many nuclei
Muscle fiber
Skeletal muscle cells
Perimysium
Connective tissue that surrounds each muscle fasciculus
Muscle fasciculus
Bundle of muscle fibers
Epimysium (fascia)
Connective tissue that surround entire skeletal muscle (outside)
Myofibril
Thread like proteins that make up muscle fibers
Myofilament
Proteins that make up myofibrils
Ex. Actin and myosin
Sarcoplasm
Cytoplasm of muscle fiber
Sarcolemma
Cell membrane
-contains T-tubules
T-tubules (transverse)
Wrap around sarcomeres at A band
Associated with sarcoplasmic reticulum
Sarcoplasmic reticulum
Type of smooth ER (SER)
Surrounds myosin
Stores and releases Ca2+
Motor neuron
Nerve cells that carry action potentials to muscle fibers
Neuromuscular junction
(Synapse)
Stupid hoe couldn’t just say that. Shiet.
Where nerve cell and fiber meet.
I’m gonna leave random shit places now to bug you while you study. Holla.
Presynaptic terminal
End of nerve cell.
The axon bitch.
Postsynaptic membrane
Muscle fiber membrane
Synaptic cleft
Space between presynaptic terminal and postsynaptic membrane.
Synaptic vesicle
In presynaptic terminal (nerve side)
Store and release neurotransmitters
Ex. ACh
Resting membrane potential
Charge difference across the membrane of a resting cell.
Outside cell Inside cell
Na+ K+
+ charge - charge
No channels closed. Some K+ open
The inside of the cell is negative even though K+ is positive because it is able to diffuse out the cell freely but other larger negative molecules can’t.
Action potential
“Electricity”
Causes muscles to contract
Stimulus that causes rapid depolarization and repolarization
Depolarization
Change in charges
Inside becomes more positive and outside more negative
Na+ channel is open
Repolarization
Na+ channels close
Change back to resting potential
Hyperpolarization
To increase polarization of membranes of muscle cells
Neurotransmitter
Chemical that stimulates or inhibit a muscle fiber
ACh
Acetylcholine
Motor unit
Group of muscle fibers that motor neuron stimulates
Actin
Thin myofilament
Contain myosin binding sites
Troponin
Attachment site on actin for Ca2+
Tropomyosin
Filament on grooves of actin
Attachment site on actin for myosin (head)
Myosin
Thick filament Resemble golf clubs Have 3 properties: 1. Bind to attachment sites 2. Bend and straighten during contraction 3. Break down ATP
Sarcomeres
1 contractile unit
Contains actin and myosin