A&P Unit Exam 3

How much of the bodies mass is made up of muscle?

1/2

How do muscles work?

by pulling

What are the 7 functions of the muscular system?

movement, maintain posture, stabilize joints, generate heat, protection, breathing, and communication

How much of the body’s heat is produced from skeletal muscles contracting?

50-80%

How do skeletal muscles cause movement?

exterting force on tendons, pulls bone

What is the origin?

attachment of tendon to stationary bone at the beginning of muscle and proximal

What is the insertion?

attachment of muscle’s other tendon to movable bone, at end of muscle and distal

What are actions?

main movements of muscle that occur during contraction

What are fiber patterns?

different organization of fascicles

What are circular muscles?

fascicles look like a circle. Creates a sphincter that can open and close

What are parallel muscles?

fascicles run parallel to muscles long axis

What are convergent muscles?

fascicles merge towards a common site and can pull in varying directions

What are pennate muscles?

fascicles are organized as if part of a large feather

What are the 3 types of pennate muscles?

unipennate, bipennate, and multipennate

What are unipennate muscles?

fascicles on same side of tendon

What are bipennate muscles?

fascicles on both sides of tendon

What are multipennate muscles?

multibranches

What does muscle coordination mean?

what one muscle group does another undoes

What is the prime mover or agonist?

produces main movement

What is the antagonist?

reverses main movement. On the opposite sides of joint across which they act

What is the synergist?

helps prime mover by adding extra force or by reducing unnecessary movement

What is the fixator?

also a synergist and immobilizes the muscles origin giving a stable base for the prime mover

How are muscles named?

size, shape, action, direction of fibers, origin & insertion, location, and number of heads/origins

What are the 4 things all muscles have?

excitability, contractibility, extensibility, and elasticity

What is excitability or repsonsiveness?

ability to receive and respond to stimuli. 

What is the response to a stimulus in a muscle cell?

An action potential (AP) that can trigger muscle contraction.

What is the response to a stimulus in a neuron?

A neural impulse (nerve signal).

What causes a cell to respond to a stimulus?

Electrical changes in the membrane or chemical signals that activate ion channels.

Voltage-gated channels

respond to changes in membrane voltage

Ligand-gated channels

respond when a chemical messenger binds to them

What is contractility?

the ability of muscle to produce force and shorten when stimulated

What is an isometric contraction?

Muscle produces tension without changing length. Example: holding a book still with your arm outstretched

What is an isotonic contraction?

Muscle produces tension while changing length. Example: lifting a book off a table.

What is extensibility?

The ability of muscle to be stretched without being damaged

What is elasticity?

the ability of muscle to return to its resting length after being stretched.

What is in the muscle organ?

muscle tissue, connective tissue, blood vessels, nervous tissue

What is a myofiber?

each muscle is a separate organ composed of hundreds of thousands of elongated fibers(cells)

What are the other names for a myofiber?

muscle fiber or muscle cell

What surrounds myofibers, fascicles, and muscles?

connective tissue

What is hypertrophy?

enlargement of cells. Stimulated by testosterone and GH

What are satellite cells?

support cells, help regenerate damaged muscle fibers

What are somatic motor neurons?

neurons that stimulate skeletal muscles

What are neurons in contact with?

every muscle fiber and capillaries

What is fascia?

sheet or band of irregular connective tissue(collagen) that surrounds muscles. Fibrous CT

What is epimysium?

denser CT surrounding entire muscle,  extends as tendon to muscle

What is perimysium?

fibrous CT surrounding fascicles

What is endomysium?

fine areolar CT surrounding each fiber

What is a tendon?

cord that attach a muscle to bone

What is aponeurosis?

broad, flattened tendon

What is a fascicle?

bundle of muscle fibers

What is a myofibril?

rod-like structures that make up myofiber. Runs along muscle fiber length. makes up 80% of muscle fiber

What is a muscle?

bundle of fascicles

What is a myofilament?

protein filaments that make up myofibrils and sarcomeres

What is actin?

Thin filament that binds myosin heads involved in contraction.

What is tropomyosin?

blocks myosin binding sites in relaxed muscles.-regulatory protein

What is troponin?

binds tropomyosin, binds actin, and binds calcium-regulatory protein

What is myosin?

thick filament, thin tail with 2 heads. The head binds actin and ATP

What’s the development of skeletal muscle?

Embryonic cells(myoblasts) fuse together with multiple nuclei, long fibers. Some will remain as single cells, called satellite cells

What is the sarcolemma?

cell membrane

What are t-tubules?

 folds of sarcolemma. Runs between cisternae pairs. Pass electrical signals to the myofibrils

What is the sarcoplasmic reticulum?

Interconnecting tubes surround myofibril where calcium is stored. Regulates intracellular calcium

What is sarcoplasm?

cytoplasm of muscle fiber

What is the mitochondria?

location of aerobic respiration and responsible for high amounts of ATP production

What does myoglobin do?

holds oxygen in myofibers

What do glycosomes store?

glycogen

What are sarcomeres?

smallest contractile unit

What are filaments?

function in contractile process. actin (thin) and myosin (thick)

What are structural proteins used for?

 help align thick and thin filaments, hold them together. 

What does titin/connectin do?

stabilizes myosin and anchors thick filament to Z disc and M line

What does dystrophin do?

links thin filaments to sarcolemma

What is striation?

striped appearance by alternating light and dark bands

What is a A band?

dark band that contains thick filaments

What is the I band?

light band that contains thin filaments

What is the H zone?

lighter center of A band

What is the M line?

middle of sarcomere

What is the Z disc(z line)?

boundary of sarcomere and the thin filaments attatch here

What is membrane potential?

steady electrical charge difference across a membrane when cell is not sending a signal. At rest and has potential to send a signal

What is resting membrane potential?

potential when a cell is at rest

What are the two conditions needed for RMP?

unequal ion distribution and unequal positive/negative charges

Where is potassium more concentrated?

inside cell

Where is sodium more concentrated?

outside the cell

What maintains the unequal distribution of potassium and sodium?

The sodium potassium pump that moves sodium out and potassium in

Which side of the membrane is more positive at rest?

the outside

What is the electrical charge inside a resting cell?

negative

What is action potential?

a rapid change in membrane potential that rises and falls

What is depolarization?

inside of cell becomes less negative(more positive)

What is a nerve impulse?

electrical signal produced by action potentials traveling along a neuron

What is the first stage of contraction?

excitation of skeletal muscle fiber

What is the 2nd stage of skeletal muscle contraction?

excitation/contraction coupling

What is the 3rd stage of skeletal muscle contraction?

crossbridge cycling

What is neuromuscular junction?

meeting point where motor neuron communicates with muscle fiber

What are the 3 main parts of the neuromuscular junction?

synaptic knob, synaptic cleft, and motor end plate

What is another name for the neuromuscular junction?

motor unit

What are the other names for synaptic knob?

synaptic terminal, synaptic bulb, and presynaptic membrane/cell

What are other names for motor end plate?

post synaptic membrane/cell/sarcolemma

What is the synapse/junction?

meeting of two cells, region where communication occurs between nerve/muscle, nerve/gland, and nerve/nerve

What is the synaptic cleft?

gap that separates the two cells

What is a neurotransmitter?

chemical released by initial cell communicating 

What are the synaptic vesicles?

 sacs suspended within synaptic end bulb

What happens in excitaiton?

Calcium entry at synaptic knob. Nerve signal travels down axon, opens voltage gated calcium channels. Calcium diffuses into synaptic knob. Calcium binds to proteins on surface of synaptic vesicles. Release of acetylcholine from synaptic knob