Revision 1: Introduction to CVS/Anatomy of CVS Flashcards
Factors affecting exchange of substances between blood in capillaries and surrounding tissue
98% of exchange is done by diffusion, which is affected by:
1) area available -> cap. density
2) diffusion resistance -> nature of barrier and molecules, also the distance that diffusion occurs over, the path length
3) conc. gradient, depends on flow of blood through capillaries to maintain this
Blood flow in the body
ml/min
Brain 750
kidneys 1200
heart 300->1200
gut 1400->2400
skel. muscle 1000->16000
skin 200->2500
rest of body 200
OVERALL ~5000->24,500
describe the major functional components of a circulation system -> CVS
pump -> heart
distribution vessels -> vessels
flow control -> via resistacne vessels, the arterioles and pre-capillary sphincters
capacitance -> veins store blood that can be used when a higher CO is necessary
distribution of blood volume over major parts of circulation
67% in veins
17% in heart and lungs
11% in arteries and arterioles
5% in capillaries
Artery types, defining features and structures
Elastic/Large arteries: intima: endothelial cells arranged w/ long axis parallel to artery length
Media: main feature is 40-70 fenestrated elastic membranes w/ SMCs and collagen in between the lamella
Adventitia: layor of fibroelastic CT w/ vaso vasorum, lymphatic vessels and nerve fibres
Muscular: intima: endoth w/ subendo. layer, thick intenral elastic lamella
media: main feature is 40 layers of SMCs w/ prominent external elastic lamella
adventitia: non-prominent vaso vasorum w/ lymph vessels and nerve fibres
Arterioles: defining feat. is a diameter <0.1mm, 1-3 SMCs in media (in smaller ones a single SMC encircles the vessel), scant adventitia
-Metarterioles: supply blood to cap. bed, different from arterioles as they have a non continuous layer of SMCs - pre cap. sphincters that allow for flow control
layers of a blood vessel
tunic intima (endothelium and sub-endothelial layer)
internal elastic lamella
tunica media (SMCs, collagen)
external elastic lamella
tunica adventitia (CT, w/ vaso vasorum sometimes)
capillary types and structure
Continuous: most common, found in nervous, muscle and CT, lungs, exocrine glands
- continuous endoth layer joined by tight/occluding junctions
Fenestrated: found in gut, endo. glands, renal glomerulus
-windows/interruptions exist across thin parts of endoth.
Discontinuous/sinusoidal (aka sinusoids): found in liver, spleen, bone marrow
-gaps allow whole cells to move across, the lumen is much wider than usual and the flow rate is slower
Pericytes form a branching network on the outer surface of the endoth., can divide to muscle cells/fibroblasts in angiogenesis, tumour growth, wound healing
veins types, defining features and structures
Venules: diam. 0.05-1mm, SM fibres begin to assoc. w/ endoth (media starts to form)
-post capillary: more permeable than cap.s, w/ a similar structure (has pericytes), low press. so fluid drains into it, site where WBCs enter blood
Medium/small veins: well developed adventitia, superf. veins of legs have well defined muscle wall to resist distension from gravity, valves act w/ contraction to return blood to heart
Large veins: eg vena cava, iliac, internal jugular, well developed longitud. orientated SMCs in adventitia in addition to circularly arranged SMCs in media
name major arteries
name major veins
name major coronary arteries and cardiac veins
anterior interventricular=left anterior descending
name major coronary arteries and cardiac veins of posterior heart
