4. CIRCULATORY SYSTEM Flashcards
arteries
taking blood away from the heart
-absorbs and stores pressure to even flow to capillary bed
veins
returning blood to the heart
lymphatics
thin walled vessels, blind ended
- collect fluid and return it to primary circulatory system
endothelial cells
prevent clotting, allow macrophages to infiltrate tissue, help control growth
what do endothelial cells secrete?
paracrine factors
what pressure does the pulmonary circuit work at?
low pressure
what happens if the lungs are at high pressure
edema
what is edema?
lungs fill w fluid and no gas exchange can occur
what 4 things make up the pulmonary circuit?
pulmonary veins
pulmonary arteries
right atrium
right ventricle
what makes up systemic circulation
left atrium
left ventricle
aorta to systemic arteries
systemic veins
what pressure does the systemic circuit operate at?
high pressure bc long distances
myogenic
contracts spontaneosly
autorythmic
controlled by sinoatrial node (pace makers set rythm)
right ventricle
delivers blood to polmonary circuit
pericardium
fluid filled sac
reduces friction from heart beating (reduces damage)
perkinje fibres
conducting systm in ventricles
where does contraction of the ventricles start?
at the apex which forces blood up
what does the left ventricle do?
muscular-pumps to the systemic circuit
what is the endocardium made up of?
endothelium –> squamous cells
what is the subendocordial layer
conducting signal for contraction
what does the subendocordial layer possess?
modified myocytes, fewer myofibrils, purkinje fibres
what are mesothelial cells important for?
fluid secretion (into pericardium)
epicardium
outer wall of heart
coronary vessels
blood supply to the heart
windkessel
elastic resevoir in artery walls for an even flow
venules, veins
functions at low pressure
acts as volume resevoir
velocity =
1/ x-sectional area
mesothelium
present in blood vessels in cavity
not present when vessel is embedded in tissue/organ
artery vs vein
arteries
-thick wall and small lumen
-more elastic
-low compliance
veins
-have thin wall and large lumen
- high compliance
elasticity
tendency to return to intial structure thats being distended (recoil)
from inside in what are the layers of arteries and veins?
intima
endothelium
subendothelial layer
internal elastic lamina
media
external elastic lamina
adventitia
vasa vasorum
what is vaso vasorum
like a coronary vessel in heart (but for large blood vessels)
- oxygenated + nutrient rich blood delivery
why is the adventitia bigger in veins then arteries?
takes up more space in veins to replace area
what is intima made up of?
squamous epithelia; loose connective tissue
-may have some smooth muscle
- fenestrated
what is media made of?
concentric layers of helically arranged smooth muscle
- reticular fibres and proteoglycans
what is adventitia made of?
connective tissue layer, type i collagen , elastic fibres
function of the muscular artery
distribution of blood + organs
help regulate blood pressure + blood flow
muscular artery ; vasoconstriction
smaller diameter
muscular artery; vasodilation
larger diameter
what does smooth muscle do?
wrap arterioles and metarterioles
- regulate blood flow and contribute to blood pressure regulation
what is the metarteriole
the terminal arteriole branch before capillary bed
relaxed precapillary sphincters
ring of smooth muscle cells
relaxed blood flow to capillary beds
shunting
temperature regulation (avoid blood going to skin)
capillaries
smallest vessel
thin wall
extensive surface area
optimized for exchange
pericycle role?
contractile
secretes ECM
regulates permeability of capillaries
three types of capillaries
- continuous capillary
- fenestrated capillary
- sinusoid
continuous capillary
most common
least permeable
regulates and transcellular exchange
fenstrates capillary
fenstrates capillary
holes and gaps within endothelial cells
junctions in between
more leaky
sinusoid
very large gaps/holes
high rate of exchange = important in liver
where are fenstrated capillary found?
intestine and kidney
where are sinusoidal capillary found?
bone marrow and liver
venous return
- smooth muscle contraction- movement
- muscle pumping surrounding skeletal muscle
- valves- prevent unidirectional flow
lymphatic capillary
blind ended
collection
no red blood cells
lymphatic vessels
go to lymnodes then return to the venus system
three major tunics/ layers of blood vessels
intima, media, adventitia
