test 3 - CV system pt 3 Flashcards
where does the pulmonary circuit begin and end?
- starts at pulmonary trunk
- ends at left atrium receiving blood from pulmonary vein
where does the systemic circuit begin and end?
- begins at aorta
- ends at right atrium
what are the 3 layers of a blood vessel wall from superficial to deep?
1) adventitia
2) media
3) intima
blood vessel wall layer: adventitia
- superficial
- thick CT (mostly collagen, some elastin) that binds vessels to surrounding tissues
- thickest layer in veins
blood vessel wall layer: media
- middle
- smooth muscle and loose CT
- alters vessel diameter and BP (vasoconstriction and dilation)
- external elastic membrane
blood vessel wall layer: intima
- deepest
- endothelial lining and dilation of CT
- internal elastic membrane
what are the 3 types of arteries?
1) elastic
2) muscular (aka distribution)
3) arterioles
what are examples of elastic arteries?
- aorta
- pulmonary trunk and arteries
- brachiocephalic trunk
- subclavian artery
- common carotid and iliac arteries
elastic arteries - characteristics
- large lumen
- thick intima
- media has a lot of elastic fibres (high pressure)
- few myocytes (do not respond to SNS or local factors)
what are examples of muscular (aka distribution) arteries
- radial
- ulnar
- basilar
- popliteal
- brachial
- vertebral
- splenic
- renal
muscular arteries - characteristics
- moderate lumen
- media is thicker with many more myocytes (under SNS and local factor control)
- prominent internal elastic membrane
arterioles - characteristics
- small lumen
- only visible with a microscope
- thin adventitia
- media is 1-2 layers of myocytes
- control BF between arteries and capillaries
atherosclerosis - def
- build up of plaque in artery
- can cause angina or myocardial infarction if in coronary artery
what are the 3 types of capillaries?
1) continuous
2) fenestrated
3) sinusoids
which are our most common capillaries?
-continuous - found everywhere except epithelia and cartilage (need blood flow)
continuous capillaries
- found everywhere except in epithelia and cartilage
- endothelium forms a complete lining, and endothelial cells connected by tight junctions and desmosomes
- single endothelial cell wraps all the way around the lumen
-only small molecules (e.g. ions) can pass
fenestrated capillaries
- contain windows, or pores, in their walls, due to incomplete or perforated endothelial lining
- far more permeable - allows molecules as large as peptides and small proteins to pass
- e.g. choroid plexus of brain, small intestine, endocrine glands, kidneys
sinusoids
- discontinuous capillaries
- resemble fenestrated capillaries that are flattened and irregularly shaped
- sinusoids are larger, and have gaps between endothelial cells
- sinusoids have thin basement membrane (sometimes absent)
- e.g. liver, bone marrow, spleen, adrenal glands
what is a capillary bed?
network of capillaries supplying blood to a specific organ or area of the body
what happens in a capillary bed?
-facilitates the exchange of nutrients, gases, wastes, and hormones between the blood and tissue cells
is the rate of blood flow constant in capillary beds?
- no
- blood flow can vary considerably
- BF occurs in series or pulses
- BF also changes due to anastomoses, metarterioles (precapillary sphincters)
what are the 3 types of veins?
1) large veins
2) medium sized veins
3) venules
give examples of large veins
- superior and inferior vena cava
- subclavian vein
- renal vein
- portal veins
large veins - characteristics
- intima and media are thin and difficult to distinguish
- adventitia is thick (collagen, elastin, and some myocytes)
