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126 Cards in this Set

  • Front
  • Back
Why are muscle fibers striped?
Because myofibrils are striped
repeating unit, from z line to z line
thikc filament, A band (dark)
thin filament, I band (light)
H band
area created when muscle is relaxed and is and area where myosin is present but not actin
thick filament structure
many myosin proteins wound together. each myosin protein has a thickened region on the head
thin filaments
actin protein molecules twisted into a double helix
proteins that block binding sites on actin at low calcium concentrations, the muscle is relaxed
calcium binds to this protein which causes a conformational change in tropomyosin, allowing myosin heads to bind to actin and cause muscle contraction
sacroplasmic reticulum
stores calcium, muscle fiers
somatic motor neurons
nerve cells found on skeletal muscle
made by axons of somatic motor neurons with many fibers
motor unit
the set of muscle fibers in contact with (innervate by) all axonal branches of a given motor neuron
the numbers and sizes of motor units vary and variation allows for gradations in motor movement (needed for coordination)
fine degree of control
few muscle fibers per neuron (smaller motor units)
muscles that need power and force
require large numbers of fibers per neuron (larger motor units), leg muscles
selective activation
most muscles contain a variety of motor unit sizes
weak/strong contractions
activation of a few small motor units/additional motor units are activated
type I fibers
slow twitch, muscle in the leg=sustained contraction, low fatigue, high number of capillaries, respiratory enzymes, myoglobin, mitochondria, red fibers
type II fibers
fast twitch, eye, high fiber thickness, low number of capillaries, mitochondria and myoglobin, hence white fibers
intermediate muscles
between fast and slow, calf muscle
Where do skeletal muscles at rest obtain energy from?
aerobic respiration
During exercise
anaerobic respiration occurs for 45-90 seconds, then glycogen and blood glucose are used
intensity of exercise level varies with
individuals capacity for oxygen uptake
muscle fatigue
decrease in muscles ability to generate force, directly related to high lactic acid formation
weight training does what to cells?
increase cell size, called hypertrophy
cardiac muscle
makes up heart, cells interconnect and link (at structures called intercalated discs) creating a single, functional unit, the myocardium
smooth muscle
no striations, surround vessels and organs. many are under involuntary, neural control
what composes the overall digestive system?
alimentary canal and solid organs
innermost layer
mucose, lines the lumen (opening). functions vary with location (ex. esophagus-lubrication; small intestine-absorption)
2nd layer
submucosa, contains blood and lymph vessels
3rd layer
muscalaris, contains external muscles for support (circular, longitudinal, oblique-stomach only)
outermost layer
serosa (aka peritoneum), a thin layer of connective tissue surrounding the abdominal cavity
mechanical digestion
teeth breakdown the food forming a ball (bolus) of food
chemical digestion
saliva and enzymes secreted from salivary glands. polysaccharides broken down into dissacharides by salivary amylase
blocks the trachea
food moves through the alimentary canal by
peristalsis contraction of smooth muscle
STOMACH function
breakdown (AKA digestion, AKA hydrolysis), partial breakdown of protein
gastric pits of mucosal cell layer contain gastric glands that secrete
parietal cells secrete
chief cells secrete
pepsinogen, breaks down protein
solid food is converted to a semi-liquid called chyme
pyloric shincter
terminal digestion of carbs, lipids, proteins occur and digestion products (monomers of these molecules) are absorbed
terminal digestion and absorption
sections of the small intestine
duodenum, jejunum, ileum
accessory (solid) organs produce HCO3 which
neutralizes acid as chyme enters the duodenum and jejunum
pancreas secretes
digestive enzymes
liver secretes
bile which stimulates the gall bladder to secrete bile (helps breakdown)
these organs secrete into ducts
that empty into the duodenum
small cytoplasmic finger-like projections, in the small intestine, epithelial cells of the mucosa
LARGE INTESTINE (colon) function
concentration of waste, reabsorption of water, ions, vitamin K
cecum and appendix are
vestigial structures
three main portions of the large intestine
ascending, transverse, descending (rectum)
e coli function
consume undigested food and secrete amino acids and vitamin K for absorption
fecal matter
dead bacteria, undigested food, plant fibers, cell debris
exocrine organ
secretes enzymatic fluid into duodenum through pancreatic duct
endocrine gland
islets of langerhans. cells in this region secrete important hormones
alpha cells secrete
beta cells secrete
insulin, together regulate blood glucose levels
(exocrine)=bile pigments and salts
liver function
produces bile, storage and/or break-down of glycogen, synthesis of glucose, production of blood plasma proteins, destruction of RBCs, detoxification of drugs and alcohol, regulates lipid metabolism, involved in lactic acid metabolism
gall bladder
stores bile
hormone which triggers release of HCl and pepsinogen when food is seen
hormone secreted in response to fat. stimulates addition of bile to duodenum
CHAPTER 49, circulation
Open circulatory system
circulating fluids (blood) and extracellular fluid body tissues (aka interstitial fluid aka lymph) are mixed collectively called hemolymph
closed circulatory systems
blood is enclosed within vessels and circulated by a pump, the heart
countercurrent heat exchange
cold, incoming blood from surface areas (skin) is warmed by warm blood from torso because arteries and veins are right next to each other
constriction of vessels
vasoconstriction, low blood flow, low heat loss. dilation of vessels (vasodialtion)-high blood flow, high heat loss
leaves the heart
goes to the heart
Inner artery later
middle artery layer
smooth muscle dilates or contracts to accomodate pressure
connective tissue (collagen) for support and elasticity
expansion and contraction of elastic, arterial wells. (evens out the blood spurts as the blood leaves the heart under high pressure)
veins function
transport, contain some tissues, but not as thick as artieries
Why can veins move easily to the heart?
thin walls, large lumen (vessel openings) cause a low resistance to blood flow
capillary function
capillary composition
madae of endothelial cells, only 1 cell layer thick (for diffusion)
enxtensive branching causes...
low speed of blood flow for more efficient exchange
small vessel diameter means...
high resistance to flow
3 ways to exchange across capillaries
1. across cell membrance of endothelial cell
2. endocytosis/exocytosis
3. pores and clefts (between cells-except in NS) allow water and ions to cross
exchange is based on
osmotic pressure (due to osmotic concentration) and hydrostatic pressure (pressure of fluid in vessel)
lymphatic system functions
drainage of extracellular fluid, part of immune system, absorption of fat from intestines
pathways of the lymphatic system
fluid in extracellular spaces goes to lymph pores (lacteals) goes through lymph system to heart, lymph collects in thoracic duct and is returned to bloodstream via syperior vena cava (in neck)
transport in lymphatic system
aided by body (skeletal) muscle contraction and smooth muscle contraction in vessels
leave the heart
go to the heart
cardiac output
CO (volume of blood moved per contraction)
blood flow
both atria fill simultaneously, both atria contract, both ventricles fill, both ventricles contract
sino-atrial (SA) node. bundle of tissue in wall of right atrium
atrio-ventricular node (AV node)
a bundle of tissue between the right atrium and right ventricle
bundle of his and Purkinje fibers
conducting nerve fibers that go from AV node around both ventricles
heart sounds: lub
atrial ventricle valces closing
valves between ventricle and arteries closing
arterial blood pressue is determined by...
total volume of blood being pumped(C0) and resistance to blood flow
blood pressue measured as:
(systolic pressure=ventricular contraction)/(diastolic pressue=atrial filling)
receptor cells in carotid arteries (neck) and in arch of aorta that detect changes in arterial pressure
thirst stimulates release of ADH from posterior pituitary. Cause kidneys to keep more water in blood, less excited, raises blood volume
kidneys experience decreased blood flow and release angiotensis II causing vasoconstriction. Causes stimulation of adrenal cortex, releasing aldosterone. net result: high sodium and water retention in blood
atrial natrioretic hormone
opposite action of aldosterone. high blood volume stretches right atrium which release atrial natriuretic hormone. action=low sodium, water in blood
nitric oxide
a gas that causes smooth muscle to relax, vessels dilate, blood flow increases.
fick's law
diffusion rates across membranes vary with surface area, concentration differences (gradients) and distance
barometric pressure
pressure of all gases in atmosphere at sea level or atmospheric pressure=760 mm Hg
Where are gills located
between mouth and operculum (flap)
What does opening and closing of the mouth do?
opening the mouth forces out water into cavity, closing mouth forces water over gills
Why were gills replaced by lungs?
1.complex structure of the gills could not be supported by air (requires water to buoy it up)
2.The large surface area of gills would cause rapid decline in water from gills to air
amphibians breathing
have low surface area and positive pressure breathing. supplement oxygen uptake with diffusion across skin (cutaneous)
all other terrestrial vertebrates
negative pressure breathing (higher pressure outside the body, gases want to come in)
Mammals pathway
O2 in nose and mouth ->
pharynx ->
larynx ->
trachea ->
split into two lungs, bronchi ->
bronchioles ->
aluedi, lined with capillaries
Why do birds have the most efficient respiration?
cross-current flow of air and blood plus unidirectional air flow as a result of air sacs allow this to happen
mechanical control of breathing
breath (inhalation or inspiration) causes intercostals and diaphragm to expand increaing the volume in the thoracic or chest cavity. pressure is higher outside (negative pressure) so air rushes in
relaxation of muscles and diaphragm
oxygen is carried in the blood by
the tetrameric (4 chain) protein hemoglobin (Hb)
HB + 4O2 yields
binding to Hb involves
allosteric effect (AKA conformational change in Hb protein aka cooperativity)
The Bohr effect
when CO2 levels are high, acidity increases
increase CO2, increase H+, Hb release O2
decrease CO2, decrease H+, Hb binds CO2
hemoglobin binding sites can also bind
NO, affects blood flow, and CO leads to irreversible competitive inhibition and death