chapter 6 muscular system Flashcards
how many skeletal muscles are in the human body?
over 700
what are the 3 types of muscle?
1) skeletal muscles
2) cardiac muscles
3) smooth muscles
what do skeletal muscles attach to?
1) attached to bones
2) some facial muscles attach to skin
where is cardiac muscle found?
walls of the heart
where is smooth muscle found?
mostly in the walls of hollow internal organs(except heart)
how is skeletal muscle controled?
voluntarily controled by nervous system
how is cardiac muscle controlled?
involuntarily controlled by the nervous system and hormones
how is smooth muscle controlled?
involuntarily controlled by:
1) nervous system
2) hormones
3) chemicals
4) stretch mechanism
what attaches skeletal muscle to bone?
tendons
what is endomysium?
connective tissue that encloses a single muscle fiber(cell)
what is perimysium?
connective tissue that wraps around a fascicle
what is epimysium?
connective tissue that covers the entire skeletal muscle
what is fascia?
connective tissue on the outside of epimysium
what is a fascicle?
a bundle of muscle fibers
what are the 4 important roles of skeletal muscle?
1) contract to cause or prevent movement
2) maintain posture and body position
3) stabilize joints
4) generate heat
what is sarcolemma?
specialized plasma membrane of muscle cells
what are myofibrils?
long fiber like organelles within skeletal muscle cells
what are I bands and A bands?
(I) light and (A) dark bands on myofibril that gives muscle cells a banded appearance
what are thin myofilaments made of?
actin protein
what are thick myofilaments made of?
myosin protein `
what is a sarcomere?
the contractile unit of a muscle fiber (cell)
what is the functional and structural unit of a skeletal muscle cell?
sarcomere
what is the length of a sarcomere?
the length between one Z disk and the next
myofilaments with myosin heads =
thick filaments
filaments made of actin =
thin filaments
what is actin?
contractile protein
what is actin anchored to in a muscle cell?
Z disks
when do H zones in muscle cells disappear and why?
during contraction because actin and myosin filaments overlap
what filament contains ATPase?
thick filaments
what does ATPase do within muscle cells?
split ATP to release energy for muscle contractions
what are the special functional properties of skeletal muscle?
1) irritability
2) contractility
3) extensibility
4) elasticity
what is irritability?
AKA responsiveness- the ability to receive and respond to stimuli
what is contractility?
ability to forcibly shorten when an adequate stimulus is received
what is extensibility?
ability to be stretched
what is elasticity?
the ability to recoil and resume resting length after stretching
what do skeletal muscles need to be stimulated by in order to contract?
a motor neuron (nerve cell)
what is a motor unit?
one motor neuron and all the skeletal muscle cells stimulated by it
what is a neuromuscular junction?
association site between the axon terminal of a motor unit and the sarcolemma of a muscle cell
what is a neurotransmitter?
a chemical released by a nerve upon the arrival of a nerve impulse in the axon terminal
what is acetylcholine and how is it abbreviated?
the neurotransmitter that stimulates skeletal muscle (ACh)
what is a synaptic cleft?
the gap between nerve and muscle filled with interstitial fluid
do nerves and muscles make contact?
no
what is the only energy source that can be used to directly power muscle contraction?
ATP (adenosine triphosphate)
what are the 3 pathways to ATP regeneration?
1) direct phosphorylation of ADP by creatine phosphate
2) aerobic respiration
3) anaerobic glycolysis and lactic acid formation
what is the fastest method of ATP regeneration?
direct phosphorylation of ADP by creatine phosphate
where is CP stored?
muscle cells
how does direct phosphorylation of ADP by CP work?
1) after ATP is depleted, ADP remains
2) CP transfers a phosphate group to ADP to regenerate ATP
how quickly does it take for CP to regenerate ATP?
15 seconds
how much ATP does 1 molecule of CP produce?
1 ATP
where does aerobic respiration occur?
mitochondria
when does aerobic respiration supply ATP?
during rest and light/moderate exercise
what does mitochondria use as energy sources?
1) glucose
2) fatty acids
3) amino acids
what does mitochondria break glucose down into and how much ATP is produced?
1) glucose is broken down into carbon dioxide and water
2) about 32 ATP is produced from 1 glucose molecule
how quickly does aerobic respiration produce ATP and what is required?
slow reaction that requires continuous delivery of oxygen and nutrients
what does anaerobic mean?
without oxygen
what is the full term for anaerobic pathway?
anaerobic glycolysis and lactic acid formation
what does lactic acid do to muscles?
causes muscle soreness
what does anaerobic glycolysis and lactic acid formation break down, and what does it produce?
breaks down glucose and produces pyruvic acid
1 glucose molecule = 2 ATP
what element causes muscle soreness?
lactic acid
what are suspected factors that contribule to muscle fatigue?
1) ion imbalance
2) oxygen deficit and lactic acid accumulation
3) decrease in ATP supply
after exercise how is oxygen deficit repaid?
rapid deep breathing
if muscle activity is strenuous and prolonged, what occurs?
muscle fatigue
what are 2 ion imbalances that can occure?
1) calcium imbalance
2) potassium imbalance
which type of exercise makes metabolism more efficient?
aerobic exercise
what type of exercise is isometric?
resistance training
what type of exercise is aerobic exercise?
endurance exercise
note the rules for determining muscle actions
1
on appendages, where is the insertion point usually located?
the distal side
on appendages, where is the origin of the muscle usually located?
on the proximal side
flexion =
when the angle of the joint is decreased
extension =
the opposite of flexion
what is hyperextension?
when the angle of a joint is extended beyond 180 degrees
what are typical joints that flexion occurs in?
1) hinge joints
2) ball and socket joints
rotational movement =
movement of a bone around its longitudal axis
what type of joint is rotation common in?
ball and socket
what is abduction?
movement of a limb away from the body
what is adduction?
movement of a limb toward the body
what is circumduction?
when proximal end of bone is stationary and distal end moves in circle
what is circumduction a combonation of?
1) flexion
2) extension
3) adduction
4) abduction
what type os joint is circumduction common in?
ball and socket
dorsiflexion =
lifting the foot so the surface is closer to the shin
plantar flexion =
pointing toes away from the head
inversion =
turning sole of foot medially
eversion =
turning the sole of foot laterally
supination =
forearm rotates laterally so palms face anteriorly
pronation =
forearm rotates medially so palms face posteriorly
opposition =
moving the thumb to touch the tips of other fingers on the same hand
prime mover =
the muscle with the major responsibility for certain movement
antagonist =
the muscle that opposes or reverses a prime mover
synergist=
muscle that aids a prime mover in a movement or reduces undesireable movement
fixator =
they hold a bone still or stabilize the origin of a prime mover
what is muscle atrophy?
wasting of muscle tissue resulting in reduction of size, tone, and power
muscle hypertrophy =
increase in muscle size
how do muscles increase in size?
repetative stimulation of muscle fibers
what happens inside a muscle cell to make it bigger?
myofibrils and myofilaments increase in numbers thus increasing size of cell
what is a charley horse?
sudden involunary contraction of one or more muscles
what can cause charley horses?
1) dehydration
2) pregnancy
3) age
4) certain medical conditions
whats a grade 1 muscle strain/pull?
stretching or minor tear
whats a grade 2 muscle strain/pull?
partial tear
whats a grade 3 muscle strain/pull?
muscle ruptured
what causes a strain/pull?
overuse or improper use of muscle
what does scar tissue on muscle increase and decrease?
increases risk of reinjury and decreases range of movement
what is the neurotransmitter that stimulates skeletal muscle?
acetylcholine (ACh)
