midterm 2 ch 6 Flashcards
Muscle tissue % of body weight
40% (males) 32% (females)
Skeletal muscle
produces movement, generally under voluntary control
Cardiac muscle
the heart
Smooth muscle
involuntary. (Food through digestive tract, diameter of blood vessels, etc.)
Muscles contract
distance shortened between bones (for skeletal muscles), then relax
Skeletal muscle moves bone, attached by
tendons
Synergistic
different muscles work together for a movement (turning the head)
Antagonistic
different muscles produce opposite motion. (reciprocal innervation: antagonistic groups do not contract at the same time)
triceps and biceps attached to bones by
tendons
when flexing, you bring tip of ulna closer to
shoulder
A muscle
all cells with the same insertation and origin are part of the same muscle.
Fascicles
bundles of cells, connective tissue surrounding each bundle joins, forming tendons.
single muscle cell
fiber
in each fiber there is
myofibril
in each myofibril there is
sacromere
Skeletal muscle cells are
multinucleic
Thick filaments
myosin
when we flex
sacromeres shorten, muscle shortens
skeletal muscle
is as long as the muscle itself
Thin filaments
strands of actin molecules
Contraction
formation of cross bridges between myosin and actin filaments
Relaxation
no more cross bridges, filaments passively slide back into place
important proteins of muscle contraction
Actin and myosin
Z lines
attachment points for actin. Muscle contraction: shortening many sarcomeres
Signal for muscle contraction begins in
frontal lobe of the cerebral cortex
_________________ take the message from the brain, down the spinal cord and to the muscles
Motor neurons
Motor neurons release ______________, (a neurotransmitter) which diffuses to the muscle cell membrane and binds to protein receptors
Acetylcholine A
______________________ is generated
Muscle electrical impulse
Electrical impulse stimulates release of calcium ions into the cell cytoplasm, from the ___________reticulum
sarcoplasmic
Steps of muscle contraction: Calcium binds with __________. Tropomyosin protein moves, exposing actin binding sites to myosin.
troponin
Energized myosin heads bind with actin, forming ______________. After binding, the myosin head bends, bringing Z-lines _______________. Next ADP + P released.
cross-bridges, closer together
ATP binds to __________ heads, causing them to release the actin filament.
myosin
Myosin heads split ATP into ___________ and the head becomes energized. It can now attach to actin again if the muscle is still being stimulated to contract (back to step 6 above).
ADP + P
Nervous stimulation causes release of
calcium ions
Nervous stimulation ends =
no more calcium ions released
Calcium is pumped back into the ___________________.
sarcoplasmic reticulum
Calcium removed from _________
troponin
Actin-binding site covered by ________________, myosin no longer can bind with actin
tropomyosin
Sarcomere ____________ as z-lines move further apart
relaxes
No nervous stimulation = no calcium ions =
muscle relaxation
One motor neuron stimulates _________ muscle cell.
more than one
A motor neuron + all muscle cells it stimulates are a _________
motor unit
All muscle cells in a motor unit _________ when nerve signal arrives.
contract
Skeletal muscles do not contract without ______________.
nerve input
Source of energy: ATP
1) ATP stored in cell used first by muscles (_____ sec)
10
ATP replenished by variety of means:
2) _______________________ (stored, transfers phosphate to ADP) (25 more sec)
Creatine phosphate
3) _______________ (in muscles, broken down anaerobically or aerobically) (5 - 10 more min.)
Stored glycogen
4) ______________________ with glucose, triglycerides, proteins. Increased heart rate / breathing rate takes a few minutes: anaerobic respiration and oxygen debt often occur before that
Aerobic cellular respiration
Muscle fatigue:
muscles cannot contract, even when stimulated by motor neurons to do so.
Why?
_________________ + __________ that accumulates in muscle cells can lead to muscle fatigue.
Low ATP supply, lactic acid
How do you stop fatigue?
________________________ and ________ (breaks down lactic acid and allows ATP to be replenished in muscle cells) Exercising aerobically only in the future.
Taking deep breaths, resting
______________: break down ATP slowly, sarcoplasmic reticulum not as close to myofibrils = contract slowly.
For endurance: more mitochondria, well supplied with blood (for oxygen / nutrient supply), stores oxygen in myoglobin
(“red” muscle), low glycogen, low creatine phosphate.
Better at long term, aerobic respiration.
Slow twitch fibers
___________________: break down ATP quickly,
sarcoplasmic reticulum close to myofibrils
For power: more glycogen and creatine phosphate
for generating ATP anaerobically, less mitochondria,
less blood vessels, no myoglobin (“white” muscle).
Better at short, anaerobic bursts of power.
Fast twitch fibers
Muscles have both types, in different relative amounts.
.
Muscles of back contracting for your posture: more _______ twitch fibers.
slow
Muscles of the fingers: more ______ twitch fibers.
fast
There are differences between people too, due to their _________ and the ________________ they have done in their life.
genetics, athletic training
_____ twitch (red muscle): endurance, long duration contraction. (Running marathons, long-distance swimming and biking)
Slow
____ twitch (white muscle): strength, short duration contraction. (Sprinting, weight lifting)
Fast
____ twitch muscle for quick bursts of power / strength
Strength training / Resistance training
_______, _________ workouts
Builds: more fast-twitch myofibrils, stores more glycogen and creatine phosphate
Builds more muscle mass / power
Fast, Short, intense
Well developed fast twitch muscle = more muscle mass = ____________, better ability to manufacture ATP anaerobically
more power
_____ twitch muscles for endurance.
Aerobic training / Endurance training
_____, ____________ work-outs
Increases blood vessels to muscle cells, more mitochondria, more myoglobin created in slow-twitch muscles
Builds endurance
Well developed slow twitch muscles = efficient creation of ATP aerobically for long time periods.
Slow, Long, sustained
Benefits of exercise for muscles:
Builds \_\_\_\_\_\_\_\_\_\_\_ (Strength training) Boosts \_\_\_\_\_\_\_\_\_\_ (Endurance training) \_\_\_\_\_\_\_\_\_\_\_\_: regular exercise slows muscle deterioration (some cells lost, other cells lose myofibrils as you age, starting at about age 30). Muscle tissue burns up calories (like fat), and more muscle mass means it is easier to control your weight.
muscle mass
endurance
Slows aging
______________ mimic testosterone, and cause more muscle protein synthesis.
This results in larger, more-powerful muscles.
Disadvantages to steroid use (men and women):
______ tumors / cancer, _________ tumors, _________, ________
(men): breast development, rage, shrinking testes, infertility
(women): facial hair, deepened voice, menstrual cycle change
(adolescents): premature halting of growth (loss of cartilage growth plate) = very short for the rest of their lives.
Anabolic steroids
Liver, kidney, severe acne, baldness
Location / function:
Skeletal: attached to _______ with tendons for voluntary movement
Smooth: ________ walls, _____ walls, _________ system, ____________ system, _________ system.
Involuntarily controls blood vessel diameter and hollow organ movements
Cardiac: heart, involuntarily pumps blood
bones
artery, vein, digestive, reproductive, urinary
Structure:
Skeletal: ______, _______ and ______________
Cardiac: _____, with blunt ends connected by gap junctions
Smooth: _____________ joined with gap junctions
Long, cylindrical, multinucleated
Short
Small spindle cells
_______________ allow contraction signals to move between cells quickly, such that large numbers of cells (joined together) basically contract simultaneously.
Gap junctions
__________ arrangement of actin and myosin shortens and fattens smooth muscle cells.
Always partially contracted, but do not fatigue, as they contract slowly and do not use up all their ATP
net-like
___________ muscles: some muscle cells pulled apart, if muscle becomes stretched too far
Pulled
____________ muscles: underused sarcomeres are damaged during exercise. Deteriorate and replaced, but hurt while this occurs
Sore
Muscle cramps: muscles contract uncontrollably. Usually after heavy exercise, caused by a combination of factors including: ___ depletion, __________, _____ imbalances and ___________ build up.
ATP, dehydration, ion, lactic acid
bacterial toxins over-stimulates nerves to muscles, resulting in constant contraction. Death by exhaustion or respiratory failure
Tetanus
sex-linked genetic disease in which muscles waste away. Death may occur as heart muscle or muscles for inhalation die, usually in the 20’s. The person is in a wheelchair in their teens.
Duchenne Muscular dystrophy
