Circulatory System Flashcards
function of circulatory system (2)
- rapidly transport substances throughout the body
- hormones, nutrients, immune cells, gases, waste
arteries
- blood vessels that carry blood away from the heart
veins
- blood vessels that carry blood toward the heart
general circulation patterns (2)
- arteries branch into network of smaller arterioles leading to the capillaries, where the exchange of nutrients, gases, and wastes take place
- blood drains from the capillaries into venules, then passes through a series of larger and larger venules, then into veins which carry the blood back to the heart
vasoconstriction (2)
- contraction of smooth muscle in walls of blood vessels
- decreases blood flow through vessel
vasodilation (2)
- relaxation of smooth muscle
- increases blood flow through the vessel
what does vasoconstriction and vasodilation allow for
- regulation of distribution of blood flow throughout the body, particularly in arterioles and small arteries
how is blood flow into the capillary beds controlled (3)
- precapillary sphincters: rings of smooth muscle that act as valves
- when they contract, they constrict blood vessels, reducing the flow of blood through that vessel
- when they relax, the vessel dilates, increasing the blood flow through that vessel
branchial circulation
- blood flow to and from the gills
systemic circulation
- blood flow through all the regions of the body except the gas exchange surfaces
single circulation
- when blood passes only once through the heart during a complete circuit
pulmonary circulation
- blood flow to and from the lungs
double circulation
- blood is passed twice through the heart during one complete circuit
hepatic portal system (3)
- all vertebrates
- delivers blood directly from lining of digestive system to the liver
- metabolize possible toxins from digestive tract and for storage/regulation of glucose
branchial circulation
heart -> ventral aorta -> afferent branchial artery of aortic arches -> capillaries -> efferent branchial artery -> dorsal aorta
actinopterygii
- aa III, IV, V, VI supply gills with blood
- sinus venosus, atrium, ventricle, bulbus arteriosus
basic structure of the heart
- 3-4 distinct chambers arranged in series
- chambers are separated with one-way valves
myogenic heart
- cardiac muscles can stimulate themselves to contract
sinus venosus (2)
- chamber with the fastest rhythm and sets rhythm for rest of heart
- cardiac muscle cells are electrically coupled
conus arteriosus (3)
- contractile heart chamber composed of cardiac muscle
- once ventricle has contracted fully and begins to relax, the conus arteriosus contracts to to prolong period of blood flow
- contraction also closes conal valves, preventing backflow of blood as the ventricle relaxes
bulbus arteriosus (4)
- heart chamber composed of smooth muscles; it does not contract, but is very stretchy
- when the ventricle contracts, this stretches and slowly recoils, gently squeezing blood into the ventral aorta
- prolongs period of blood flow, minimizes pressure surges
- bulbal valve prevents backflow of blood as ventricle relaxes
cardiac shunt
- crocodilians can control whether they send blood in right ventricle to the lungs or to systemic circulation
when do crocodilians use the cardiac shunt/when do organisms favour mixing of blood (3)
- used when diving or during feeding
- diving: deoxygenated blood still has some O2 to help with cellular respiration
- eating: deoxygenated blood delivered to the stomach capillaries to increase acidity in stomach and aid in chemical digestion
why do birds and mammals have no mixing of deoxygenated and oxygenated blood
- both need high metabolic rate to maintain endothermy, which requires efficient circulation and delivery of O2 to tissues
what would happen if right ventricle was as strong as the left ventricle (2)
- blood pressure in pulmonary arteries would be too high and fluid would be forced out of the capillaries into the alveoli or air capillaries
- pulmonary edema would results; essentially drowning
why is left ventricle so strong
- must pump blood to the entire systemic circuit, so it must generate a for large enough to overcome large resistance to blood flow of many systemic capillary beds of the body
mammal diving adaptations: vasocontriction (3)
- large amounts of vasoconstriction to areas that are not essential during diving
- helps to maximize available O2 use during long dives
- increases blood pressure as a result, but can be counteracted with slowing of heart rate
mammal diving adaptations: aortic bulb
- elastic, non-pumping enlargement of aorta helps to maintain constant blood flow while diving
