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
