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Anatomy CH7 Muscle System

Terms in this set (126)

skeletal muscles move

bones (directly or indirectly)

smooth muscles move

substances in tubes/organs (involuntary)

characteristics of cardiac muscle

- branched
- contain intercalated discs
- striated
- small, one nucleus
- has desmosones and gap junctions attaching to nearby fibers
- involuntary, controlled by pacemaker cells in the atrium
- no summation, no tentanus
- Ca+ comes from sarcoplasmic reticulum
- contains myoglobin

cardiac muscle is ___ meat and ____ twitch

dark meat and slow twitch (bc needs to be aerobic so the heart keeps beating)

stores oxygen in muscle cells giving them aerobic respiration and a dark color

cardiac muscle does not

get stimulated by a neuron

How many skeletal muscles are there?

cardiac muscle moves

blood in and out of the heart

characteristics of skeletal muscle

- voluntary
- striated
- multinucleated
- not branched
- has summation and tentanus
- anerobic and aerobic respiration
-red and white meat

characteristics of smooth muscle

- small, one nucleus
- involuntary, can self stimulate (no nerve impulses) and be stimulated by the involuntary part of the brain
- unbranched
- nonstriated
- fibers look unorganized
- calcium is replaced by sarcoplasmic reticulum
- no tetanus or summation -*anaerobic respiration? rapid contractions? white?

all muscles _____ and are built to get _______

all muscles contract, and are built to get shorter

list the 5 functions of the muscular system

1.) move the skeleton- use voluntary skeletal muscles

2.) maintain posture/body position- baby can't sit up on own

3.) support soft tissue- shield the body from blows, found at the bottom of cavities, and support the weight of organs

4.) guard entrances/exits- beginning of digestive system/urinary system

5.) Maintain body temp- contact muscle -> use ATP -> get ATP from breaking down glucose -> only 20% of glucose goes to ATP, 60% given off as body heat

muscle cells are

elongated (and referred to as muscle fibers)

List the types of tissue found in a muscle

connective tissue, blood vessels, nerves

connective tissue contains

3 layers
epimysium, perimysium, endomysium

outermost layer around the muscle, mostly made of collagen with elastic fibers. used to attach to other structures

connective tissue that surrounds a group of muscle fibers/cells aka FASICLES. supplies the fassicle w blood vessels and nerves

connective tissue that surrounds 1 individual muscle fiber and attaches itself to other neighboring fibers. contain stem cells which repair damaged tissue.

the perimysium and the endomysium are used to

bring in blood vessels and nerves

blood vessels within the muscle cause the muscle to

require lots of oxygen

bands of collagen fibers attach skeletal muscle to bones and the fibers are interwoven with the periosteum of the bone

connect different skeletal muscles to each other

at the ends of the epimysium, perimysium, and endomysium ( a muscle)

the collagen fibers all come together at the ends (candy shape) to determine whether it is a tendon or aponeurosis

muscle fibers can be up to

2 feet long, and are multinucleated. that is huge

outer membrane that can conduct electricity and contain little holes that transverse (go across/through) the entire cell. highly excitable

these small holes/tubes within the sarcolemma are called

T tubules. (opening of outer membrane that goes through the entire cell). they are filled with extracellular fluid

cytoplasm of a muscle cell (fiber)

sarcoplasmic reticulum

surround each myofibril, contain high amounts of calcium (which is then used to uncover the actin/beads)

Myofibrils are composed of

composed of 2 types of microfilaments- thin filament (actin/beads) and thick filament (myosin/heads)

myofibrils contain ?

1000s of sacromeres (smallest functional unit of a muscle fiber), along with actin and mysoin

the A band characteristics

myosin, dark, doesn't change length

the I band characteristics

light, actin, contracts/shortens

gets smaller when contracts

zone of overlap

where thick and thin filaments overlap, gets bigger when muscles contract (bigger gap)

Middle of sarcomere, holds thick filament in place, doesn't move

skeletal muscles only contract

under stimulation of the CNS. axons penetrate the epimysium, go through the perimysium, and enter the endomysium. this means most muscles have voluntary control but some are subconscious

thick filaments (myosin)

look like golf clubs (heads)term-42

thin filaments (actin)

look like pearl necklaces (beads)

the actin beads have a high __________ towards myosin

affinity/attraction.

since they have this high attraction, actin beads must be ___....

covered by tropomyosin so that they do not attach to myosin when not contracting

is held in position by toponin, which is bound by the actin strand.

if calcium attaches to troponin,

the tropomyosin strands unlock the actin/myosin filaments, allowing them to bond together, creating cross bridges that allow for muscle contraction

once the crossbridges are formed ?

they snap towards the middle (M Line) pulling the actin filaments with it, creating a contraction

there is a high concentration of calcium in

the sarcoplasmic reticulum

what causes the release of calcium onto troponin

Sodium (Na+) is located outside the muscle fiber on the sarcolemma, the Na gates open and Na rushes into the synaptic terminal space (the cleft)

the synaptic terminal is

the end of motor neuron which releases a chemical (neurotransmitter) into the space (synaptic cleft) between nerves and muscles

nerve cell which controls the skeletal muscle and branch through the perimysium to reach several muscle fibers (fassicles)

how to the sodium (Na+) gates open

ACh (neurotransmitter) opens the gates by attachment

Why is ACh released?

Calcium is located in high amounts outside the synaptic terminal, when the impulse reaches the synaptic terminal, calcium rushes in and forces exocytosis of the vesicles that hold ACh

overview of this whole process

1.) actin becomes exposed after troponin bonds with calcium, and myosin bonds form (cross bridges) w/ the actin. the myosin snaps inwards toward the middle
2.) ATP breaks the crossbridge and myosin goes back to its normal position, bonds with a new actin, and repeats the process
3.) This process continues until calcium is pumped back (calcium returns to normal levels) into the sarcoplasmic reticulum and the tropomyosin covers the actin

sacromere shortening + tension : tension

myosin heads grab the actin and pull causing a contraction.

sacromere shortening + tension : ACh

ACh opens the Na+ gates of the sarcolemma of the muscle fiber

sacromere shortening + tension : resistance

a force that opposes tension

sacromere shortening + tension : Achase

acetylcholinesterase. enzyme that destroys the neurotransmitter

MUSCLE FIBERS CAN ONLY

CONTRACT. there is NO way to lengthen a sarcomere

push applied to an object

generic order of a twitch

1st impusle by neuron -> gate released = contraction -> calcium pumped out

3 phases of a twitch

latent, contraction, relaxation

ACh is released and attached to the Na+ gates, they open -> Na+ rushes in and forces the release of calcium by sarcoplasmic reticulum (calcium is on the actin). no tension yet. 2msec

contraction phase

how long the calcium stays on the actin/rope. maximum tension after 15 msec

relaxation phase

ACh is destroyed by ACh ase, sodium gates close and Na+ gets pumped out, Ca+2 is pumped back into the sarcoplasmic reticulum

true or false: you only need one stimulation/twitch of a muscle fiber to contract a muscle

FALSE. you need THOUSANDS of impulses per second

muscles are always using multiple

impulses bc ACh is always released into cleff and Na+ is always going into a muscle cell

muscles twitches that add onto each other (bumpy hill)

2 reasons for a muscle to contract

1.) frequency (how many impulses are sent)
2.) # of muscles/ muscle fibers used

2 types of frequency

incomplete tetanus and complete tetanus

incomplete tetanus

bumpy hill
lots of muscle stimulation /summination but is not necessarily smooth. all muscle contractions have incomplete tetanus. Does not go above maximum tension

complete tetanus

fast impulses that reach maximum resistance/tension to smoothly contract (appears as smooth contraction w/ no time in between). relaxation phase eliminated. action potential arriving so fast the sarcoplasmic reticulum do not have time to reclaim calcium ions

Explain # of muscles/ muscle fibers used effect on contraction

- always try to stimulate the least amount of fibers
- motor units

the nerve and numbers of muscle fibers it stimulates..

if a motor unit stimulates lots of muscle fibers

you get more power (calf)

if a motor unit stimulates a small amount of muscle fibers

you get precision (fingers)

recruitment happens when

one (1) motor unit is not able to overcome the resistance on its own, and is not enough.
it will recruit other motor units within that muscle, or gain help from other muscles

motor units must be able to

communicate with surrounded motor units

if 3 motor units control a muscle, and one of the motor unit starts contracting

only 1/3 of the muscle will contract

every muscle in the body must have a small % of it contracting at all times (rotate between motor units). if this does not happen, the muscle dies from lack of use.

stiffness of the body that sets in several hours after death

muscle death after lack of muscle tone (use)

tension depends on

how many hands (myosin) on the rope (actin) and are actively shortening, the fibers resting length at the time of stimulation (H band) and the frequency of stimulation (effects how much Ca on the tropomyosin)

overcome resistance

there is no regulation of how many

sacromeres in a myofibril can contract at once, it just depends on whenever the calcium is released by the sarcoplasmic reticulum

what are the 2 types of muscle contractions

isotonic and isometric

isotonic contractions

tension increases but exceeds the resistances (hill crosses line), and the muscle shortens/contracts. Ex: bending of the arm, lifting a weight

isometric contractions

the tension increases but does not exceed the resistance and the muscle never changes length/contracts. Ex: sitting straight up, pushing a pull door, lifting truck, pushing a wall

how does the muscle get back to its resting length

1.) it has an opposing muscle- biceps when contracted, shorten the biceps movement. triceps contract it lengthens the bicep.
2.) the 3 conn tissue layers around the muscle (epi, peri, endomysiums) have elastic fibers that extend the muscle at rest.
3.) Gravity pulls it back

fassicles/cells are the ???

same length as the organ

When a muscle fiber contracts

it uses 600 trillion ATPs per second

aerobic respiration

the production of ATP by breaking down glucose (organic compounds) with the use of oxygen
has 3 stages- glycolosis, Krebs cycle, and ETC

taking sugar (glucose) and cutting it in half by enzymes so it can fit in the mitochondria
2 C6H12O6 becomes 2 C3H6O3 (pyruate). then the 1 H is taken by carriers to get 2 C3H5O3. These carriers are NADH. This produces 2 ATPs. Occurs in the cytosol of the cell.

FINAL PRODUCT: two C3H5O3 (pyruvate) , two NADH (carriers), and 2ATPs

take the pyruvates (glucose) and strip the remaining Hs off.
where? mitochondrial matrix (cytosol).
who? enzymes
in -> 2 pyruvates
out > 10 carries (H) and 2 ATPs
waste -> O2

ETC (electron transport chain)

take all 12 carriers (2 from glycolysis, 10 from Kreb) and take them to the membrane. Takes all the energy off the electrons in Hydrogen to one side of the membrane which creates a high concentration of H+s. Pumps the hydrogen from an area of low concentration to high.

produce ATP from ADP + P (No Oxygen)
1 molecule of glucose = 2 ATPs = anerobic respiration

adenosine diphosphate

adenosine triphosphate

the movement of oxygen

resting muscles store

more ATP than how much is used, and 6x the amount of phosphates on a protein called creatine.

ATP in resting muscles

stored and lasts for about 2 seconds (after 2 seconds you put the phosphates on the creatine).

creatine + ATP in resting muscles

creatine phosphate + ADP
creatine phosphate speeds up the movement of phosphate to creatine
ATPs control the creatine phosphate

reverse reaction of creatine phosphate in resting muscles

CP + ADP --> ATP + Creatine

- run out of ATP in 2 seconds
- next 10-12 seconds -> use CP to give ADP another phosphate
- now anerobic or aerobic respiration must occur

if you can breathe during your exercise

aerobic.
glycolosis (2 ATPs), Kreb (2 ATPs), ETC (32 ATPs).
mitochondria needs oxygen

if you are gasping/gassed during your exercise

anerobic respiration (glycolysis only)

anaerobic respiration

Hydrogens are given back from the carrier proteins to create
2 HC3H5O3 -> Lactic Acid. This lactic acid then is dumped into the blood, which makes you gasp for air. Lactic acid goes to the liver to get converted back to pyruvate (glucose). but this requires a TON of ATP and aerobic respiration making this type of work out more taxing.

muscle cannot contract even when stimulated by nerve because it is out of energy/glucose, has too much lactic acid buildup, and not enough oxygen

2 types of muscle fibers

fast twitch and slow twitch

fast twitch fibers

- contract in 0.01 seconds
- fattest/widest muscle fibers
- filled to the max with myofibrils (means less space for mitochondria)
- stored with glycogen (long chains of glucose)
- used for power but get tired/fatigued really quickly (hands and eyes)
- build up on each other
- anerobic exercises (sprints)

fast twitch, anerobic

slow twitch fibers

- smaller in width/narrow
- have less myofibrils (therefore less power)
- filled with capillaries, arteries, and veins (bring/store O2)
- have lots of mitochondria
- contain myoglobin
- slower muscles bc it takes longer to activate mitochondria
- aerobic, last longer and don't run out of energy quickly

examples of slow twitch muscles

calves (gastronemceius), back muscles

slow twitch, contain myoglobin

3 reasons slow twitches get more oxygen

1.) they have more capillaries, arteries, and veins to bring O2 into the cell
2.) storage- contain myglobin, which stores oxygen within the cell
3.) use more mitochondria

how does ageing effect the skeletal muscle system

- mitosis goes slower
- injury becomes more long term
- less ability to do anerobic workouts
- don't have elastic fibers in muscles/ not able to stretch

where the muscle starts

where the muscle ends and moves the bone

move away from the middle

moving toward the middle

same length as the organ

fasicles, muscle fibers, myofibrils

not same length as the organ

label the sacromere

constricts entrances and exits

3 types of primary actions and their function

primary- muscle that moves the bone
antagonist- opposing muscle of the primary
synergist- two or more muscles working together to move the same bone

myofibrils are responsible for

muscle fiber contractions

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