w8 exercise physiology Flashcards
what is pair of muscles that can pull the same bone in opposite directions
antagonists
what are fascicles
a bundle of structures, such as nerve or muscle fibers or conducting vessels in plants
what makes up muscle
fasicles
myofibrils
basic rod-like organelle of a muscle cell
actin and myosin which is thick or thin
actin - thin
myosin - thick
Z lines contain what protein and do what
alpha-actinin
defines the lateral boundaries of the sarcomere and anchores thin, titin and nebulin filaments
dark area between 2 Z lines that contains what filaments
A band, thick and thin filaments
light band either side of Z line and contains what filaments
I band, contains thin filaments
light area located in the middle of A band and contain what filaments
thick filaments
dark line in middle of sarcomere that contains what proteins that are critical for organization and alignment of thick filaments
M line, myomesin protein, thick filaments
thin filaments include what
actin, troponin, and tropomyosin
what plays a key role in regulating muscle contraction
troponin and tropomyosin
what does the alkali light chain do of myosin muscle
stablize myosin head
what does the regulatory light chain do of myosin muscle
regulate APTase activity of myosin
when does a muscle contract
when thin filaments slide along thick filaments
signals from what system, conveyed by what are required to initiate and sustain muscle contraction
signals from CNS, conveyed by motor neurons
when a motor neuron sends out an action potential, its synaptic terminals release what neurotransmitter, which diffuses across the synapse to the plasma membrane of the muscle fiber
acetylcholine
what is released from the ER when a motor neuron stimulates muscle contraction
Ca2+
action potential causes channels in the ER to open, releasing what where
releasing Ca2+ into the cytoplasmic fluid
when muscle fiber is in resting state, what blocks what
tropomyosin and tropnin block myosin binding sites on the actin molecules
Ca2+ allows what as it binds to what
Ca2+ binds to troponin, and tropomyosin moves away from the myosin binding site, allowing contraction to occur
the motor unit consist of what
a single motor neuron and all the muscle fibers it activates (one set of muscle fibers)
a typical skeletal muscle receives innervation from approx how many somatic motor neurons
100
a motor neuron pool consist of what
many motor neurons, each of which innervates a motor unit w the muscle
motor units are recruited in progressive order from
smallest (weakest) to largest (strongest)
Type I and Type IIa/IIb is fast or slow
Type I - slow twitch
Type II - fast-twitch
slow twitch and fast twitch mitochondrial content high or low and fatigue level
slow - high mitochondrial content, slow rate of fatigue
fast - low mitochondrial content, rapid rate of fatigue
does strength or endurance training increase capillary supply and mitochondrial content
endurance training
how does the body meet increased energy demand in active muscle (skeletal muscle has low metabolic rate)
locally from muscle glycogen and triacylglycerols
systemically from liver glycogen and adipose tissue triacyglycerols
what is the main source of ATP for power and speed
power - stored ATP and phosphocreatine (PCr)
speed - non-oxidative breakdown of carbohydrate stored as muscle glycogen
muscle cells contain creatine phosphate, which converts what
ADP to ATP thus replenishes ATP store during muscle contraction
when high-intensity continues for more than 10-60 sec, breakdown of ATP and PCr is followed by accelerated breakdown of what
intramuscular glycogen to glucose and then to lactate
lactic acid lowers pH from what to what, which inhibits what and leads to what
7.1->6.62
inhibits glycolysis and contributes to muscle fatigue
what (2) provides immediate but limited energy
ATP and phosphocreatine
what provides rapid, but self-limited source of ATP
anaerobic glycolysis (divert pyruvate to lactic acid)
what provides a slower but long-term source of ATP
oxidation of glucose, lactate, and fatty acids
oxidation of glucose uses what from where at what time point
glucose from liver glycogen (>1 min)
what from what twitch muscles can enter what twitch muscles where it is oxidized
lactate from fast twitch muscles can enter slow twitch muscles where it is oxidized
lactate can also travel to the liver for what
gluconeogenesis
> 1 minute what energy source for muscle
oxidation of glucose/lactate
what energy source for muscle for exercise lasting longer than 30-40min
oxidation of fatty acids as mobilization of lipids from adipocytes
fatty acids enter the skeletal muscle and are oxidized
type IIb uses what pathway
anaerobic glycolysis
type I uses what pathway
oxidation of glucose/lactate or fatty acids
after 1 hr what way is used to get energy
hepatic gluconeogenesis (hapatic glycogen stores become depleted)
what are the most important substrates for hepatic gluconeogenesis
lactate and alanine
during prolonged exercise what is the key substrate that is released into the contracting skeletal muscle for uptake by the liver, which synthesizes into what for uptake by the muscle via what
key substrate lactate
via cori cycle
cori cycle
glucose is metabolized to pyruvate and then to lactate in muscle, the lactate is released into the blood and carried to the liver, where it is reconverted to pyruvate and used for gluconeogenesis, and the resulting glucose is released and travels back to muscle
cahill cycle involves what
glucose and alanine
central fatigue is due to changes in which nervous system
CNS
peripheral fatigue is due to what
changes within the muscle
what results in difficult or impossible fast movements
impaired release and reuptake of Ca2+ from SR
central fatigue due to
altered input from muscle sensory nerve fibers to the brain
altered excitability of motor neurons to the muscle
reduced excitatory input to motor control centers o the brain and spinal cord
peripheral fatigue is caused by what (3)
ATP depletion
Lactic acid accumulation (fall in pH inhibits stuff)
glycogen depletion
aerobic training increases maximum O2 delivery to muscle and increases cardiac output by (2)
hypertrophy of the heart
increased cardiac stroke volume as a result of expansion of the plasma compartment
trained muscle can accommodate a greater maximal blood flow bc of growth of what
new microvessels, particularly capillaries
increased capillary density increases O2 delivery and this provides what (2)
greater surface area for diffusion
reduction of the diffusion distance for O2 between the capillary and muscle fibers
aeorbic training can effect capillary how
increased capillary length and volume
prolonged transit time of RBC along capillaries
endurance training can increase the what content of skeletal muscles by nearly 2 fold
mitochondrial content
primary benefit from mitochondria adaptation in aerobic condition is
capacity to oxidize substrates, particularly fat, and enhances endurance of muscle
apocrine sweat glands located where
in the axillary and anogenital regions of the body
apocrine sweat glands empty into what
hair follicles
what sweat gland type may act as a source of pheromones
apocrine
where has more eccrine sweat glands
palms of hands and sole of feet
essential role of eccrine sweating is what
temp regulation
eccrine sweat glands are tubules comprising a what gland and what duct
secretory coiled gland and reabsorptive duct
is sweat glands vascular or avascular
a rich microvascular network surrounds the entire sweat gland
the coiled gland of eccrine, located deep in the dermis, is innervated by what fibers that are what
sympathetic fibers that are cholinergic
what causes eccrine sweat glands to secrete into the lumen a clear, odorless solution, similar to protein-free plasma
release of acetylcholine
how is NaCl content of sweat related to rate of secretion
directly proportional
how does NaCl content relate w acclimatization of heat
NaCl content decreases
