Module 10 Muscular System Flashcards
my/o
muscle
sarc/o
flesh
sthen/o
strength
origin
attachment of a muscle to a bone or structure that does not move when the muscle contracts
insertion
attachment of a muscle to a bone or structure that DOES move when the muscle contracts
intrinsic muscle
muscle that has its origin and insertion located in the same body region
extrinsic muscle
muscle that has its origin located in a region different from that of its insertion; ex. sternocleidomastoid
fixator
a muscle that holds an origin stable for another muscle
synergists
muscles that have the same action
prime mover
the main muscle that performs the action, helped by synergists
antagonist
a muscle that has an opposing action
sarcolemma
muscle cell’s cell membrane
sarcoplasmic reticulum
muscle cell’s ER
myofibrils
a bundle of myofibrils make up a muscle fiber
single muscle structure (smallest to largest)
individual muscle cell (muscle fiber) is surrounded by endomysium; muscle fibers are grouped together to form a fascicle which is surrounded by perimysium; fascicles together make up the muscle which is surrounded by epimysium
fascia
tough, fibrous tissue that does not allow for expansion; forms muscle compartments and separates muscle from the hypodermis
sarcomere
section of myofibril extending from one z line to the next; the overlapping of the myofilaments near the center of the sarcomere is what causes the striated appearance of skeletal muscle tissue
myosin
several hundred protein molecules that make up thick myofilaments; includes: actin, tropomyosin, and troponin
5 physiological characteristics of muscles
- excitability- ability to be stimulated by a nerve to contract
- conductivity
- contractility- can shorten with force
- extensibility- can be stretched; muscles are stretched by the contraction of other muscles
- elasticity
neuromuscular junction
shows excitability; nerve ending and muscle cell don’t touch, instead receptors with specific shape are located on the muscle cell
Acetylcholine
(ACh) neurotransmitter released for skeletal muscle tissue that signals the muscle cell to contract
threshold
minimum amount of ACh required in receptors for the muscle to react; creates an all or nothing response
synaptic cleft
AKA synapse; indentation in the muscle cell that forms a gap where the nerve ending meets the muscle; allows receptors to communicate between nerve ending and muscle cell
muscle twitch
contraction of one muscle cell due to one nerve impulse
phases of muscle twitch- 1. latent phase
muscle cell has not shorted during this phase; nerve impulse comes down the neuron; ACh is released and fits into the receptors; sarcoplasmic reticulum releases Ca+; Ca+ binds to troponin; tropomyosin shifts position to expose the active sites; myosin grabs ahold of actin
phases of muscle twitch- 2. contraction phase
myosin pulls (power stroke; the muscle cell shortens
phases of muscle twitch- 3. relaxation phase
myosin lets go; muscle goes back to its shape because it is elastic
phases of muscle twitch- 4. refractory phase
Ca+ is actively transported back to the sarcoplasmic reticulum and the muscle produces acetylcholinesterase; muscle appears to be relaxed
tetany
sustained muscle contraction due to frequency of nerve impulses that come and complete their latent phases before the muscle cell can even begin to enter the relaxation phase from the first nerve impulse
motor unit
a single nerve cell and all the muscle cells its stimulates; one nerve cell can have more than one nerve ending
recruitment
getting more and more motor units involved to get a bigger motion
isotonic contraction
tension remains constant and motion was the result
isometric contraction
increased muscle tension without movement; ex. flexing muscles
lever
rigid object that can be used to lift something; has 3 basic parts: resistance (weight to be lifted) , effort (force applied to lift), and fulcrum (pivot point)
aerobic respiration
glucose molecule (process is glycolysis)-> pyruvic acid producing 2 ATP molecules; the addition of oxygen results in CO2 and H2O and produces enough energy to form 36 ATP
muscle metabolism
chemical reactions a muscle cell uses to process energy; energy produced in mitochondria through cellular respiration; two forms: aerobic and anaerobic respiration
creatine phosphate
energy storage molecule; when energy is not immediately needed, creatine is added to ATP resulting in creatine phosphate
anaerobic respiration
glucose molecule (undergoes glycolysis) -> pyruvic acid -> converted to lactic acid (waste product); only produces 2 total ATP
fatigue
muscle inability to fully respond to nerve impulse; eventually the muscle may weaken to the point of not being able to respond at all
physiological contracture
complete fatigue in which the muscle appears to be stuck; cannot relax of contract
oxygen debt
the amount of oxygen needed to remove the built up lactic acid; once debt has been paid then the fatigue is over
slow-twitch fibers
some skeletal muscles that are specifically adapted to stay aerobic, so they are less likely to fatigue; have extra mitochondria, better blood supply (for oxygen and glucose), glycogen stores within the muscle, and myoglobin to store oxygen until needed
fast-twitch fibers
skeletal muscles that excel at anaerobic respiration
3 types of muscle tissue
skeletal, smooth, and cardiac
skeletal muscle:
long, striated with many nuclei per cell; voluntary nerve stimulus; aerobic and anaerobic; associated with bones
cardiac muscle:
striated with a single nucleus, self-stimulating, aerobic, heart
smooth
spindle-shaped cells with no striations and a single nucleus; involuntary; aerobic; hollow organs and blood vessel walls
nonessential amino acids
11 amino acids that the body can make; include alanine, cysteine, glutamic acid, glutamine, tyrosine
essential amino acids
other 9 amino acids that must come from the diet; lysine, leucine, methionine, tryptophan, etc.
complete proteins
have all nine of the essential amino acids
incomplete proteins
missing one or more of the 9 essential amino acids
functions of the muscular system
- movement
- stability
- control of body openings and passages
- communication
- heat production
effects of aging on the muscular system
lean muscle mass decreases (atrophies); fat is deposited in muscle, muscle fibers shrink; begins in the 20s for men and 40s for women; rate of atrophy genetically determined;
EMG
electromyography; procedure that asses the health of the muscles by testing how a muscle responds to electric stimuli
spina bifida
congenital; bifid=forked; results from a failure of the neural tube to close in lumbar/sacral region; spinal cord incompletely enclosed
spinal stenosis
narrowing of vertebral canal or intervertebral foramina caused by hypertrophy of the vertebral bone; occurs most frequently in middle-aged and elderly people; as the bone grows it compresses the roots of the spinal nerves
degenerative disc disease
occurs when gelatinous nucleus pulposus becomes replaced by fibrocartilage with age, sometimes destabilizing the spine and leading to subluxation of vertebrae and ruptured discs
spondylolysis
laminae of the vertebrae are defective; defective vertebrae may be displaced anteriorly, and stressed ca cause microfractures in a defective lamina and eventual dissolution of the lamina
spondylolisthesis
occurs when a defective vertebra slips anteriorly especially at the L5-S1 level; less severe may only call for pain treatment while more severe may require surgery
osteoporosis
progressive metabolic bone disease that decreases bone density, with deterioration of the bone structure; effects bone density and strength; peak bone strength is around 30yo
types of osteoporosis
Primary- occurs spontaneously; major cause is lack of estrogen in menopausal women;
Secondary- caused by another disorder or by a drug; ex. chronic kidney disease, hormonal disorders, multiple myeloma, progesterone, corticosteroids
Idiopathic- rare; cause unknown
symptoms of ostoporosis
vertebral compression fractures (fractures of spinal vertebrae), fragility fractures (common in radius, femur, trochanter, humerus and pelvis)
diagnosis of osteoporosis
bone density testing, vitamin D level, tests of causes of secondary osteoporosis
people susceptible to osteoporosis
all women 65+, women between menopause and 65 that have risk factors, all men and women who have had a fracture caused by little or no force, 65+ who have unexplained back pain or loss of 1.2” body height, thin bones (visible on xrays)
bone density testing
used to detect of confirm osteoporosis; DEXA; often checks spine and hip because they’re the most common place of major fractures
osteoporosis prevention
managing risk factors, consuming adequate amounts of calcium and VitD, engaging in weight-bearing activities, taking certain drugs (for some people)
osteoporosis treatment
calcium and VitD, weight-bearing exercise, drugs, treatment of fractures
biphosophonates
useful in preventing and treating all types of osteoporosis; shown to reduce bone turnover; can rarely cause osteonecrosis of the jaw; long-term use of bisphosphonates may increase the risk of developing unusual fractures of the femur, so doctors recommend taking bisphosphonate holidays (breaks)
calcitonin
inhibits the breakdown of bone; not prescribed frequently; doesn’t reduce risk of fracture, bud does help relieve pain they cause; nasal spray; can decrease blood levels of calcium, so levels need to be monitored
hormonal therapy
ex. estrogen; most effective when started within 4-6 years of menopause; risks may exceed its benefits for many women so not usually the option chosen
raloxifene
estrogen-like drug that may be useful in preventing and treating bone loss without estrogen’s negative side effects;
Denosumab
prevents bone loss; injection 2x a year; should not miss a dose or go on drug holiday because it may cause a loss in gone density and increased risk of vertebral fractures
Romosozumab
increases bone density in the hip and lumbar spine and reduces the risk of fracture in postmenopausal women; inject 1x a month for one year
anabolic agents
ex. Teriparatide and abaloparatide; increase the formation of new bone, increase bone density, and decrease the likelihood of fractures
