Circulatory System Flashcards
why is the lymphatic system considered a “one-way” system?
lymph is taken only towards heart, via systemic veins
contrast to cardiovascular system, in which blood travels to and from heart and tissues (two-way system)
describe how synovial fluid, cerebrospinal fluid, aqueous humor, and endolymph (ears) circulate in the circulatory system, in contrast to lymph or blood
these are non-vascular components: fluid moves between vasculature and extravascular compartments
how do anastomoses function to prevent ischemia when there is obstruction in an artery? Contrast this to what would happen in an end artery
obstruction in end artery —> ischemia, cell death
anastomoses allow for collateral circulation, dictated by pressure gradient —> blood travels to areas of low pressure (where obstruction has cut off blood supply)
*note that this may allow blood to flow in vessels in a direction that is opposite of original flow
do arteries have valves?
no arteries have valves - due to this, blood can flow in any direction as dictated by pressure gradients (ex - anastomoses)
some veins have valves that prevent back-flow and ensure unidirectional flow
elastic arteries, aka ____
muscular arteries, aka ____
elastic arteries = conducting arteries
branch into…
muscular arteries, aka distributing arteries
branch into arterioles
what are the layers of blood vessel tunics? (3)
tunica intima: simple squamous endothelium, thin connective tissue
tunica media: vascular smooth muscle cells
tunica adventitia: connective tissue
atherosclerosis
arteriosclerosis = hardening of arteries, causing arterial walls to loose elasticity
atherosclerosis is type of arteriosclerosis caused by plaques of fatty cholesterol buildup and calcium deposit
what is clinically significant about the fact that veins communicating between superficial veins of the face/scalp and deep intracranial veins do not have valves?
valves prevent back-flow
in veins without valves, direction of flow is dictated by pressure gradient
because these do not have valves, an infected thrombus can travel from superficial veins of the triangular “danger zone” in the face to deep intracranial veins
what do portal systems do?
carry blood between 2 capillary beds
ex: hepatic portal vein connects first capillary bed which supplies oxygen and nutrients to gut tissue and picks up absorbed substances from food, to second capillary bed (liver sinusoids) that filters what is absorbed
*note these systems do not have valves
true end artery vs functional end artery
true end artery: no anastomoses, no collateral circulation (ex: retinal artery)
functional end artery: have weak anastomoses and ineffectual collateral circulation (ex: heart and brain)
