Cardiovascular pressure and capacitance Flashcards
What are the 3 layers of the walls of blood vessels?
Tunica interna
Tunica Media
Tunica externa
What does tunica interna have?
epithelial inner lining
endothelium, BM (collagen fibres) Internal elastic lamina (elastic fibres)
What does tunica media have?
Elastic fibres and circular smooth muscle cells, arteries present
What does tunica adventitia have?
Elastic and collagen fibres
support and vaso vasorum
How many types of blood vessels are there?
5
What are the 2 types of arteries?
Elastic conducting
Muscular distributing
What do large arteries do?
propel blood while ventricles are relaxing - pressure reservoir
What do medium size arteries do?
Transport blood over long distances with little drop in BP
What are 3 layers of arteries?
Tunica interna - squamous epithelium BM Lamina
Thick tunica media smooth muscle
Tunica externa
Describe Arterioles?
Thin tunica interna fenestrated elastic lamin dissappears at terminal end
tunica media - 2 layers smooth circle muscle
tunica externa - elastic and collagen
smaller than arteri
Why are Arterioles important?
By vasoconstriction and vasodilation influence peripheral resistance and modify blood flow from arteries to capillaries - Resistance vessels
What is the terminal end of the arteriole?
Metarteriole - tunica interna surrounded by loose smooth mc
What is at the metarteriole capillary junction?
distalmost muscle cells from precapillary spincter monitor blood flow to capillar
What is at the distal end of a vessel?
Thoroughfare channe; - provides direct route for blood from arteriole to venule bypassing capillaries
What is Vasomotion?
Intermittent blood flow due to alternating contraction and relaxation of smc of metarterioles
How do capillaries function?
Allow exchange of fluid and metabolites between blood circ system and tissue - are exchange vessles
What do tissues with high and low metabolic rates have?
High rate (brain, liver, kidney) - abundance of capillaries Low rate - (lining epi, cornea, cartilage) few capillaries
What do venules do?
Collect blood from capillaries and consist of tunica interna and media with SMC
What are the venule walls?
Porous and function as sites for exchange of nutrients and waste and WBC - merge steadily to form larger venules to form veins
What do Veins do?
thin tunica interna and media , externa is a thick layer, large lumen
Take blood to heart
What are low pressure vessels called?
Capacitance vessels
How much of bodys blood is in veins?
64% - rest are capillaries and arteries
What are blood reservoirs?
Veins and Venules
What are the 3 routes where substances enter or leave the capillaries?
diffusion, transcytosis and bulk flow
What occurs in diffusion?
involved with flow of materials in and out of the capillaries -movement from high conc to low conc
What occurs in transcyotsis?
Small materials transported across capillary walls encapsulated within invaginations of serosal membrane (pinocytosis) transport to release by exocytosis- large hydrophilic insulin transported
What is bulk flow?
body fluid derived from ingested water and stored in blood plasma and intersitial fluid - fluid flows from blood to tissues via filtration
what does movement of blood fluids depend on?
blood hydrostatic pressure BHP
Interstitial fluid osmotic pressure IFOP
What happens in reabsorption?
pressure driven movement from interstitial fluid into blood capillaries depends on blood colloid osmotic pressure BCOPand in less on interstitial fluid hydrostatic pressure IFHP the flow of fluid from blood to tissues and back depends on forces of net filtration pressure NFP
What % of fluid is filtered out of capillaries is reabsorped?
85% excess fluid enters lymph capillaries
What is Oedema?
Increased in the interstitial fluid volume noticeable when fluid increased by 30%
What happens with excess filtration?
Oedema caused by increase capillary BP and IFOP
What happens with inadequate reabsorption?
Decrease in conc of plasma proteins and kidney disease
