Week 7 Flashcards
unique charcteristics of skeletal Muscle
Attach to bones & produce movement
Voluntary, Striated (“striped”), tubular, multi-nucleate
unique charcteristics of cardiac muscle
Only in heart
Involuntary, Striated, branched, uni-nucleate
unique charcteristics of smooth muscle
Gut muscle, blood vessels
Involuntary, Non-striated, spindle-shaped, uni-nucleate
general muscle charcteristics
- Excitability
- Ability to respond to stimulation
- Contractility
- Ability to shorten forcefully
- Extensibility
- Ability to stretch & still contract
- Elasticity
- Ability to resume resting length after contraction
functions of muscle
-Produce movement Locomotion: skeletal Blood pressure: --cardiac Propulsion: smooth -Maintain body positions and posture -Support soft tissues -Maintain body temperature -Store nutrients -Valves/Sphincters
What is Fasica
connective tissue that attaches the hypodermis to the muscle beneath
Fascia lies over the epimysium
what are the three CT layers associated with muscle
Epimysium
perimysium
endomysium
epimysium
CT that covers the entire muscle
perimysium
CT that covers the fascicles
fascicles
bundles of muscle fiber cells
endomysium
surrounds an individual muscle cell
what is the purpose of connective tissue in the muscle
Together, the three muscle connective tissue layers strengthen muscles (keep muscles from bursting under pressure) and come together to form tendons (attach muscle to bone) and aponeruoses (a tendon sheet)
levels of organization of muscle
fascicle, muscle cell, myofibril, sarcomeres, myofilaments
muscle cell
muscle fiber- covered by connective tissue endomysium, its cell membrane is called sarcolemma
sarcolemma
the fine transparent tubular sheath that envelops the fibers of skeletal muscle cells
myofibril
cylindrical structures made of repeating sarcomeres, 100s-1000s of myofibers in a muscle cell
sarcomere
the contractile unit of muscle, composed of myofilaments made of contractile filaments (~10,000 per myofibril)
myofilaments
3 kinds of filament make up the sarcomere, thick (myosin) thin (actin) elastic.
what are elastic filaments made up of
titin
what are myofibrils covered in?
sarcoplasmic recticulum
what is sarcoplasmic retculum
a specialized endoplasmic reticulum. Its job is to release calcium to induce muscle contraction
what are T tubules?
they are continuous with in the sarcolemma, and transmit the action potential throughout the muscle cell.
study the parts of the sarcomeres
STUDY IT
What do actin filaments do
actin filaments slide pass myosin filaments during muscle contraction.
what do myosin filaments do?
Myosin molecule heads bind the actin to keep the muscle from sliding backwards. Myosin heads will bind and release multiple times during a contraction, to move the thin filaments
do thin or thick filaments change length during muscle contraction?
No the thick and thin layers begin to overlap.
what happens when a muscle cells shortens
As a muscle cell shortens, the following events occur:
The I bands shorten
The distance between Z discs shortens
H bands disappear
Adjacent A bands move closer together (though their length does not change.)
what is action potential
Neurons generate an electrical impulse that is conducted down the length of the axon; the electrical impulse
At rest how is the neuron charged
negatively charged and the outside is positively charged.
what is depolarization
it is the process of equalizing out the charges between the outside of the neuron and the neuron itself
What makes the inside outside of neruron cells positive or negative?
the movement of ions
what is a synapse?
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
what is the motor end plate
motor neuron establishes synaptic contact with a striated muscle fiber.
what is the neuromuscular junction
the synapse/site of interaction between neuron & muscle cells – where neuron “meets” muscle fiber.
what are thin filaments surrounded by
troponin and tropomyosin
what are the two types of channels proteins that are responsible for action potential
- Passive channels (leak channels) are always open (potassium channels)
- Gated channels open and close in response to stimuli (sodium channels)
what ion does the membrane let out more readily.
Potatsium
where do all action potentials begin?
the brain sends an electrical signal down the axon to the muscle fibers and makes them contract
what is troponin
a binding spot for calcium on the muscle cells
what is tropmyosin
this is a organelle wall that moves and exposes the actin filaments when the troponin is unlocked
what is cross bridge formation
when myosin heads can bind to actin
what are the five steps of telling a muscle fiber to contract?
1: Action potential moves down motor neuron,
2: Neurotransmitter ACh is released into the synaptic cleft, it attaches to receptors on the sarcolemma
3: ACh binding triggers action potential in the muscle fiber being triggered.
4: Muscle Action Potential triggers Ca2+ release from the sarcoplasmic reticulum
5: Ca2+ initiates muscle contraction
what is another way to say action potential
electrical curent
what neruotransmitter signals the muscle cell?
Acetylcholine(ACh)
what is the function of titin
the function of elastic filaments(titin) is to anchor thin filaments.
what are the steps of bone reformation
- A Hematoma forms at the fracture site
- A soft callus of granulation tissue forms, regions begins to become vascularized.
- The soft callus is changed to bony callus, made of spongy bone. This takes about 2 months to complete.
- The bony callus is remodeled, excess material on diaphysis is removed, compact bone laid down to reconstruct shaft walls.
what are the six types of synovial joint
Gliding joints Hinge joints Pivot joints Ellipsoidal Saddle joints Ball and socket joints
rigormortis
is a fixed muscular contraction that occurs shortly after death, when muscle cells run out of ATP. Myosin heads cannot release from actin filaments without ATP.
what is a motor unit
a nueron and all the cells it is attached to
what is sustained tension
Allows motor units to rest in rotation
sustained tetnus
when every muscle fiber is contracted
what is meant by isotonic contraction
the muscles actually shorten
isometric contraction
the muscle stays the same length, tension is just built
what are the five steps in the contraction cycle/ cross bridge cycling
Step 0: Ca2+ binding to troponin, to move tropomyosin, which allows the active sites of actin (thin filament) to be exposed.
Step 1: Activated myosin head is drawn to and is attached to the active site on myosin, forming a cross-bridge.
Step 2: The myosin head pivots, which causes the “power stroke” to be performed, pulling actin towards the M line.
Step 3: ATP binds to the myosin head, causing the cross bridge to detach
Step 4: Myosin head is reactivate/”re-cocked” into position (to move back to step 1).
what is fine control compared to gross control in relation to a motor unit.
Fine control = 1-5 fibers (cells) per M.U. (eye)
Gross control= 1000’s of fibers (cells) per M.U. (leg)
