Unit 3 Circulatory Flashcards
CS function
distribution of hormones
transport of waste products to excretory organs
CS components
heart - pump
arteries
veins
capillaries
arteries
- carry blood away from he heart
- vessels get progressively smaller
- thicker wall than veins
- resist changes in BP in larger arteries
- regulate blood flow in arterioles
veins
- return blood to heart
converge into progressively larger vessels - lower pressure then arteries
- thinner walls and larger lumens than corresponding artery
- have endothelial covered valves to ensure one-way flow
capillaries
large number of thin walled vessels
site of exchange between blood and tissue
pulmonary (RS) circuit
receives oxygen poor blood from tissues
pumps blood to lungs to get rid of CO2, pick up O2
systemic (LS) circuit
receives oxygenated blood from lungs
pumps blood to body tissues
atria
thinner walled
receive good from systemic
ventricles
thicker walled
distributes blood to pulmonary or systemic circulation
valves
- maintain unidirectional flow of blood through heart
- atrioventricular valves separate atria from ventricles
- pulmonic valve separates right ventricle from pulmonary trunk
- aortic valve separates left ventricle from ascending aorta
cardiac skeleton
- central region of heart surrounding valves
- dense CT; may become calcified
- provides support for valves and great vessels
- anchors cardiac muscle
- annuli fibrosae
- triton fibrosae
annuli fibrosae
surround valves
triton fibrosae
triangular masses between annuli
heart wall
- endocardium
- myocardium
- epicardium
endocardium
- lined with endothelium
- subendothelium
- wubendocardial layer
subendothelium
loose CT
subendocardial layer
CT, nerves, conducting system of heart (purkinje fibers)
myocardium
thickest layer, cardiac muscle, fibrous skeleton
epicardium
aka visceral layer of pericardium
- mesothelium
- loose CT w/veins, nerves, autonomic ganglia
- adipose tissue
heartbeat impulse
- Modified cardiac muscle cells
- Sinoatrial node: in wall of right atrium near entrance of superior vena cava; cells spontaneously depolarize and initiate impulse
- internodal tracts connect sinoatrial node with atrioventricular node
- atrioventricular node – inferior wall of right atrium
- interventricular bundle of His
- left and right bundle branches – Purkinje cells
- Purkinje cells conduct to apex of heart where contraction initiated
vessel structure
- tunica intima
- tunica media
- tunica adventitia
tunica intima
inner lining of endothelium
subendothelial CT
internal elastic lamina (arteries)
tunica media
middle, concentric layers of sm
elastic/reticular fibers, proteoglycans
ext. elastic lamina (lg. arteries)
tunica adventitia
longitudinally arranged type I collagen fibers, elastic fibers, continuous with CT of surrounding organs
vasa vasorum
- walls of lg. vessels
- provide nutrition for outer layers of media and adventitia of lg. vessels
- more frequent in veins
capillaries
- 7-9 microns diameter
- single layers of endothelial cells resting on basal lamina
- cells held together by tight junctions
- pericytes
pericytes
- in capillaries and post capillary venules
- outside endothelial layer
- after tissue injury can proliferate and differentiate to rebuild vessels
types of capillaries
continuous
fenestrated
sinusoidal
continuous capillary
- widespread in muscle, lung, connective tissue, exocrine glands, nervous tissue
- no pores (fenestrae)
pinocytic vesicles invovled in transcellular transport
fenestrated capillary
- endothelial cells with fenestra (pores) and continuous basal membrane
- where rapid exchange occurs
kidney, intestine, endocrine glands
sinusoidal capillary
- much larger diameter
- discontinuous endothelia wall with fenestra
- macrophages in gaps between endothelial cells
- in liver, bone marrow, spleen
anastomoses
interconnections of blood vessels; connects arterioles and venules
sphincters open
blood flows through true capillaries
sphincters closed
blood flows through metarteriole bypassing true capillaries
metarteriole
thoroughfare channel
portal system
two capillary beds separated by vein or artery
hepatic portal system
capillaries of gut to drain to hepatic portal vein then empty into capillaries of liver
kidney portal system
glomerulus drains to efferent arteriole then to peritubular capillaries
large arteries
elastic or conducting arteries
- thick tunica intima
- thick tunica media: fenestrated elastic lamina, smooth muscle
- tunica adventitia relatively thin
medium arteries
distributing, muscular arteries
- media has more smooth muscle, less elastin
- prominent internal and external elastic lamina
small arteries/arterioles
- tunica media 5-10 layers smooth muscle in small arteries; 1-4 layers in arterioles
- adventitia: thin, blends in with surrounding connective tissue
post capillary venules
- similar to capillaries; larger lumen
2. similar función to capillaries
small and medium veins
- thin media
- well-developed adventitia
- valves
large veins
- well developed intima
- thin media
- thick adventitia: in veins inferior to heart contains longitudinally arranges bundles of smooth muscle