3. Cardiovascular system Flashcards
Functions of the vascular system
- > distribution system
- > variable resistance system
- > exchange system -> lungs CO2 to O2, Liver, uptake of nutrients and removal of waste
- > collection + reservoir system
- > oxygenated blood to upper and lower part of the system
- > comes back to right side of the heart
Distribution of blood in the different vascular compartments
- > 15 % systemic arterial system
- > 9 % pulmonary circulation
- > 7 % Heart
- > 18 % large veins
- > 21 % venous reservoirs
- > 25 % small veins + venules
- > 5 % capil
Types of blood vessels
ARTERY
conducts blood from heart to arteriole
ARTERIOLE
conducts blood to capillaries
CAPILLARY
exchange vessel
VENULE
conducts blood to a larger vein
VEIN
conducts blood back to heart
Vessel diameter
- > start with biggest artery - AORTA
- > very small diameter in capillary
- > builds up rapidly again
- > biggest diameter -> vena cava
Structure of vessels + The vascular system
TUNICA INTIMA (endothelial layer) -> pull up blood within the blood vessel controls vascular permeability, modulates vasconstriction (don't perform, cannot contract because not muscle cells), site of angiogenesis, regulates coagulation -> change pretty quickly and induce clotting => internal elastic Lamina + endothelial cells
TUNICA MEDIA (smooth muscle) embedded in extracellular matrix regulates vasoconstriction + vasodilation vessels => smooth muscle cells + elastic fibres
TUNICA ADVANTITIA (Collagenous material) fibroblast, innervated layer => smooth muscle cells, external elastic lamina, collagen
Tunica Intima
- > made up of vascular endothelial cells
- > cells anchored on top of internal elastic lamina
- > endothelial cells blood compatible
- > Haemangoblast: progenitors of endothelial (blood vessel) + Haemopoietic (bone marrow and then embed and become Haemangoblasts + blood) cells
Tunica media
- > made up of vascular smooth muscle cells (can change diameter of blood vessel, open up or close and increase pressure)
- > supported with elastic fibres -> elasticity
- > smooth muscle cells -> rhythmic contraction -> haemorpropulsion
- > SMC’s -> allow change to vessel diameter -> control blood flow
Tunica Adventitia
- > external elastic lamina
- > Some SMC’s
- > Highly thrombogenic (surround blood flow) -> forms haemostatic envelope (will stop bleeding and clot)
Vessel Structure : ARTERY
- > round with thick wall
- > endothelium rippled
- > elastic elements
- > thick tunica media
- > collagen + elastic fibres
Vessel Structure : VEIN
- > collapsed with thin wall
- > endothelium layer smooth
- > no elastic elements
- > thin tunica media
- > smooth muscle + elastic fibes, collagen -> compell blood forward and push blood forward
Capillary netweork
- > Collaterol arteries -> supplying arteries -> arteries but become smaller an change into capillaries
- > join together to become small venules but become vein
Total cross sectional area
-
Capillary structure
- > some are continuous -> some stocked next to each other
- > open structure with gaps between them so exchange can occur
- > exchange via slow diffusion
Capillary network
Continuous capillaries (exchange via slow diffusion)
Fenestrated capillaries (exchange via pores -> kidney, inestines)
Sinusoidal / Discontinuous capillaries (highly permeable -> liver, bone marrow, spleen)
Arterial side
- > higher fluid pressure compared to tissue
- > fluid leaks out into tissue
Venous side
- > Lower fluid pressure compared to tissue
- > fluid leaks from tissue back into the vessel
Capillaries - sites of exchange
=> thin walled vessels with endothelium tissue
- > CONTINUOUS (tight junction (proteins that hook together)
- > FENESTRATED (slightly holdign together -> still some exchange but not much can go through)
- > /SINUSOIDAL (open -> gaps so cells can pass through)
