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Flashcards in blood vessel structure Deck (15):

what is the pulmonary circuit

- supplied by right heart
- BV to and from heart to the lungs
- closed system


what is the systemic circuit

- supplied by left heart
- BV to and from heart to systemic tissues
- closed system


what is series flow

- blood flows in series through pulmonary and systemic circuits
- ensures all blood is oxygenated
- different pressure
- pulmonary and systemic
- exception: GI tract and liver connected in series


what is parallel flow

- blood flows in parallel through different capillary beds of systemic circuit
- systemic
- advantages: each capillary bed receives oxygenated blood, independent regulation, same pressure
- exception: GI tract and liver connected in series


what are blood vessels and the types of BV

- delivery system of dynamic structures
- ability to change shape and diameter
- heart, elastic arteries (big), muscular arteries, arterioles, capillaries, post capillary venules, small veins, large veins heart)


describe the general structure of BV

- lumen: hollow interior, flow of blood, bigger in veins than arteries
- inner lining: lines lumen, endothelial cells, flat, smooth, undisturbed flow of blood without turbulence
- muscle: some have smooth, fibrous / elastic connective tissue
- tunics: main coverings of BV, three main layers, intima, media and externa


describe the three main layers of tunics

- intima: most internal, endothelium (lines lumen), sub-endothelial layer and internal elastic membrane
- media: middle, smooth muscle, sheets of elastin, external elastic membrane, controlled by sympathetic vasomotor nerve fibres control, bigger in artery
- externa: collagen fibres (stability, protection, reinforcement) and vasa vasorum (vessels, nourish external layer)


what are / different types of arteries

- carry blood away from the heart
- oxygenated except for pulmonary arteries and umbilical vessels of foetus
- elastic (conducting): large thick walled (2.5cm), large lumen (low resistance), pressure reservoir, expansion following contraction of H, regain original shape, e.g. (carotids, subclavian, pulmonary artery, iliac artery - branch off aorta)
- muscular (distributing): distal to elastic arteries, deliver blood to organs, thin (2-10mm), thick tunica media, active in vasoconstriction, two elastic layers (IEL and EEL), affect peripheral resistance maintain pressure


what are arterioles

- small branch of arteries, conduct blood away from heart
- variable resistance, depends on contractile state of smooth muscle
- not many


how is blood vessel diameter regulated in arterioles

- nervous input regulates smooth muscles contraction in vascular system
- potent agents can affect diameter CO2 (dilate), NO (dilate), adrenaline / noradrenaline (constrict), ADH (constrict), caffeine, stimulants, histamine


what are / the types of capillaries

- microscopic, one cell thick, single RBC at a time
- contact tissue cells
- directly serve cellular needs
- passage of oxygen and nutrients
- all tissues except cartilage and epithelia
- continuous: abundant in skin and muscles, tight junctions connect endothelial
- fenestrated: contain pores, passage of bigger molecules, more permeable than continuous (kidney, intestine)
- sinusoidal: fewer tight junctions, larger intercellular clefts, large lumens, molecules pass between blood / tissue (liver only)


explain what / how the blood brain barrier is formed

- protective mechanism (stop toxic substances / bacteria / viruses from reaching brain), - endothelial cells attach without synaptic cleft
- movement via diffusion (passive or active)
- CO2, O2, and alcohol can diffuse into the brain
- therapeutic targets aim to cross the BBB (develop compound able to cross, treatment of strokes)


what are venules

- post capillary (PVC's)
- very porous, allows fluids / WBC into tissues
- endothelium, few pericytes, thin endothelial cells
- 1-2 layers of smooth muscle


what are muscular / medium veins

- from PVC's to small muscular venules
- lead to medium veins
- low BP, surrounded by skeletal muscle (contraction = pushes blood to heart)
- valves prevent back flow


what is atherosclerosis

- hardening of arteries and mild build up of plaque (fat, cholesterol, calcium)
- increased fatty diet, unhealthy lifestyle, genetic condition
- less BF to organ, inelastic arteries, increase BP
- plaque = clot, constriction, heart attack / stroke
- coronary artery: at risk, inside heart, gives blood and oxygen to heart tissue
- aorta at risk