Chapter 42: Circulation and Gas Exchange Flashcards
circulatory systems
connect isolated cells to external environment to facilitate exchange
gastrovascular cavity
lack specialized circulatory system; have a high surface area to volume ratio. ie, cnidarians, flatworms
circulatory fluid
carries resources/wastes
interconnecting tubes
component of circulatory system thru which fluid travels
heart
muscular pump
open circulatory systems
circulatory fluid (hemolymph) in direct contact with organs; same as interstitial fluid; ie, arthropods, most mollusks
advantages of open circulatory system
lower pressures, can use fluid as hydrostatic skeleton
closed circulatory system
circulatory fluid (blood) in vessels, separate from interstitial fluid; ie, annelids, vertebrates
advantages of closed circulatory systems
faster delivery of O2, easier to regulate
cardiovascular system
vertebrate circulatory system
atrium
chamber of the heart that receives blood
ventricle
chamber of the heart that pumps blood away
arteries
carry blood away from heart; branch into arterioles
capillaries
where exchange takes place
capillary bed
network of capillaries
veins
carry blood back to heart
single circulation
blood pumped thru a single circuit; in fishes with 2-chambered hearts. runs at lower pressure, so lower velocity
double circulation
blood pumped thru two separate circuits; in tetrapods with 3- or 4-chambered hearts. maintains higher pressure/velocity of blood
pulmonary circuit
circuit that pumps blood to lungs
systemic circuit
circuit that pumps blood to body
steps in the flow of blood thru both circuits
right ventricle pumps blood to lungs via the pulmonary arteries, blood flows thru capillary beds of the left and right lungs (gas exchange) and then returns to left atrium via pulmonary veins. left ventricle pumps blood out to body via the aorta (including coronary arteries to the heart). one branch leads to capillary beds in head and arms, another branch leads to capillary beds in the head and arms, another branch leads to capillary beds in the abdomen and legs. deoxygenated blood drains head and arms via superior vena cava, drains the abdomen and legs via the inferior vena cava, and both empty to the right atrium.
cardiac cycle
complete sequence of pumping (systole) and filling (diastole)
heart rate
avg. 72 beats per minute
stroke volume
avg. 70 mL per ventricle
cardiac output
avg. 5 L/minute (per ventricle)
valves
one-way flaps, bigger than the opening they cover
valve types
atrioventricular valve (AV): between chambers
semilunar valve: between ventricles and arteries
heart murmur
defective valve leads to back-flow
pacemaker
autorhythmic cells of heart; contraction based upon own electrical impulses
sinoatrial node
beginning of electrical impulses, cause atria to contract
atrioventricular node
relay electrical impulses after 0.1 s delay, ventricles contract
vessels structure
open lumen lined by endothelium (single epithelial layer)
arterial structure
layer of smooth muscle, then layer of elastic connective tissue. thicker than veins (higher pressure), muscle can contract to control flow
vein structure
layer of smooth muscle and connective tissue; thinner with valves to prevent back-flow
blood pressure change in capillary beds
total cross-section area increases; velocity of blood decreases thru the capillaries
precapillary sphincters
close off paths through capillary beds; controlled by nervous system and hormones
exchange of water by pressure
blood pressure forces water out at arterial end, osmotic pressure draws water back at venous end
lymph
network of small vessels that drains excess interstitial fluid
blood
circulatory fluid in closed circulatory system made up of connective tissue cells and plasma
plasma
liquid matrix of blood; 90% water dissolved with salts, proteins, gases, wastes, hormones, etc.
erythrocytes
red blood cells, function mainly in O2 transport. lack nuclei, full of hemoglobin
hemoglobin
oxygen transport protein
leukocytes
white blood cells; perform various immune function
platelets
cell fragments involved in blood clotting
clotting
damage plugged by platelets and reinforced by fibrin protein
stem cells
located in bone marrow, produce new blood cells
partial pressure
fraction of the total pressure exerted by air
diffusion of oxygen
must be exchanged thru water; cell membranes need moist surfaces
gills
respiratory surface of fish
countercurrent exchange (fish)
moves surface of gills through medium, capillaries flow in the opposite direction; removes 80% of dissolved O2. won’t work on land
tracheal system
adaptation for breathing air in insects, series of air tubes that branches throughout body. does not involve circulatory system
lungs
adaptation for breathing air in vertebrates
nostrils function
filter, warm and moisten air as its taken in
larynx
receives air via pharynx and opens to trachea
bronchi
trachea branches into two bronchi, which continue to branch into bronchioles
bronchioles
surface covered by cilia and mucus to remove waste; end in alveoli
amphibians ventilation
positive pressure breathing; push air in by shrinking oral cavity
mammals ventilation
negative pressure breathing; pull air in
diaphragm
skeletal muscle that expands thoracic cavity to pull air in
breathing control centers
control breathing in brain by negative feedback; coordinated with circulatory system
bird ventilation
one way flow of air by use of posterior and anterior air sacs; more efficient and complex
partial pressures of O2 and CO2
net diffusion of O2 to the blood, CO2 diffuses from blood to air, O2 is transported throughout the body, CO2 is loaded from cells to the blood
necessity of hemoglobin
transports higher quantities of O2 than water to reduce necessary cardiac output
