Vascular System Flashcards
What is the primary function of cardiovascular system?
transport of O2/CO2 and nutrients/metabolic waste
What are the secondary functions of the cardiovascular system?
thermoregulation, transport of immune cells/hormones
What makes up the vascular system?
heart and blood vessels
What are the two components of the circulatory system?
pulmonary and systemic circulation
What is pulmonary circulation?
RA and V -> pulmonary artery -> lungs -> pulmonary veins -> left atria
What is systemic circulation?
LA and V -> aorta -> rest of body
What is the lymph vascular system?
passive drainage system for returning extravascular fluid to the blood vascular system
Does the lymph system have an intrinsic pump?
no, it relies on muscle contraction and body movement
What are the three layers of the cardiac wall?
endocardium, myocardium, epicardium
What is the endocardium?
lined by endothelium with underlying layers of CT, middle layer of smooth muscle and elastic CT, and a subendotheiual layer containing modified cardiac muscle fibers
What is the myocardium?
thickest layer of the heart wall and contains cardiac muscle, connective tissue, and small blood vessels
What is epicardium?
lined by mesothelium with an underlying layer of loose CT that is rich in adipose tissue and contains small nerves and blood vessels
(also called visceral pericaridum)
What is the tunica intima?
the innermost layer of simple squamous endothelium cells lining lumen
-very thin layer, 1-2 cell thick
-form semi-permeable barrier supported by basement membrane
-specialized discontinous tight junctions (fascia occludens)
-variable amounts of subendothelial CT
What is the internal elastic lamina?
elastic tissue that separates tunica intima and media
What is the tunica media?
highly variable middle layer
-smooth muscle cells and fibroblastic CT
-in arteries, thickest of the layers, may contain reticulin and elastic fibers
What is the external elastic lamina?
elastic fibers located between the tunica media and adventitia
What is the tunica adventitia?
outer most layer of blood vessels
-thickest layer in veins
-contains vasa vasorlum (mall blood vessels to supply the media and adventitia)
-contains nervi vasculares (autonomic nerves)
What causes vasoconstriction?
sympathetic, post ganglionic fibers
What is the process of vasodilation?
passive
-occurs in absence of sympathetic stimulation
-indirect parasympathetic innervation
Where are baroreceptors located and what do they do?
in carotid sinus and aortic arch
-detect blood pressure
Where are chemoreceptors and what do they do?
at bifurcation of carotid artery and aortic bodies in aortic arch
-detect changed in O2, CO2 tension, and pH
What do arteries do?
conduct blood from the heart to the capillaries
-store pumped blood during cardiac systole to ensure flow during cardiac diastole
What are the three major tunic/layers of arteries?
-tunica intima
-tunica media
-tunia externa
What are the three major groups of arteries?
-large elastic arteries
-medium sized muscular arteries
-small arteries/arterioles
In which blood vessel is blood pressure the largest?
aorta/arteries
What are elastic arteries?
> 1cm in diameter
-large conducting vessels (aorta, common carotid, subclavian, pulmonary arteries)
-have sheets of elastic tissue in tunica media, help maintain bp between systole and diastole
-have both internal and external elastic laminae
What is the thickest layer of elastic arteries?
tunica media
Two major characteristics of large elastic arteries:
-they receive blood from the heart under pressure
-keep blood circulating continuously while the heart is pumping intermittently
What do large elastic arteries do during systole?
distend
What do large elastic arteries do during diastole?
recoil
Where are large amounts of fenestrated elastic sheaths found in large elastic arteries?
tunica media
What are the blood vessels within large elastic arteries?
vasa vasorum
What are nerves in the large elastic arteries?
nervi vasorum
Where are the vasa vasorum, nervi vasorum, and lymphatics of large elastic arteries located?
tunica adventia
What are examples of large elastic arteries?
aorta and its largest branches (brachiocephalic, common carotid, subclavian, and common iliac)
What are muscular arteries?
2-10 mm in diameter
-more smooth muscle and less elastin in tunica media than elastic arteries
-tunica media is the thickest layer
-internal elastic layer and may or may not have external elastic lamina
What do muscular arteries do?
allow selective distribution of blood to different organs in response to functional needs
What are the three layers of tunica intima of muscular arteries?
-endothelium
-subendothelium
-internal elastic lamina
Examples of medium sized arteries:
radial, tibial, splenic, mesenteric, and intercostal arteries
What are arterioles?
-final branches of arterial system
-10-100 um in diameter
What do arterioles do?
regulate distribution of blood to different capillary beds by vasoconstriction/vasodilation
Where does partial contraction/tone happen?
arterioles
What regulates distribution of blood into capillaries?
pre-capillary sphincters
What are metarterioles?
small diameters arterioles; intermediate in size between arterioles and capillaries
-characterized by discontinuous of smooth muscle in tunica media
What are postcapillary venules?
drain capillary beds
What part of the capillary bed always have blood in them?
thoroughfare
What part of the capillary bed may or may not have blood in it?
true capillaries
What are functional units of the cardiovascular system?
capillaries
What are the layers of the capillaries?
only has the tunica intima
-basement membrane and endothelium only
-small # of pericytes
do capillaries have vasomotor activity?
no
-vasodilation and vasoconstriction accomplished via smooth muscle contraction in arterioles and pre-capillary sphincters
What are continuous capillaries?
lined with endothelium with tight junctions and a basal lamina with pericytes
What are fenestrated capillaries?
have pore or fenestrate (holes)
What are sinusoid capillaries?
discontinuous
-incomplete endothelial lining and basal lamina with gaps and holes
What does Nitric oxide and prostacylin do?
relaxation of smooth muscle
What can prostacylin do to blood clotting?
prevent platelet adhesion and clumping
What is endothelin 1?
potent vasoconstriction peptide
What type of cells have the greatest permeability to leukocytes?
postcapillary venules
What activates activated endothelium?
cytokines
What does activated endothelium allow?
-emigration of lymphoid cells
-express cell adhesion molecules for neutrophils
What are Weibel-Palade bodies?
storage granules found in endothelium of arteries, veins, and endocardium
What is inside Weibel-Palade bodies?
von Willebrand factor and P-selectin
What is von Willebrand factor?
factor essential for blood coagulation
-binds with factor VIII and leads to platelet adhesion
What does P-selectin do?
increase permeability of endothelium and facilitate leukocytes leaving the blood stream
What is a vasoactive factor that cause cells to lose attachment to one another?
histamin
Do both arteries and veins have valves?
no just veins
What are post capillary venules?
beginning of venous system right after capillaries where blood cells migrate into tissues
Which have thinner walls, arteries or veins?
veins
Small muscular arteries…
may or may not contain internal elastic lamina
Medium muscular arteries…
contain external elastic lamina only
large muscular arteries…
contain internal and external elastic laminae
What do vasoactive substances do to venules?
enlarge intercellular spaces
-increase permeability of vessel
What causes varicose veins?
valves of the veins do not close properly and allow the blood to pool in the veins
What are AV shunts?
direct connections between the arterial and venous system
-bypass capillary
What are portal vessels?
vein or artery directly connecting two capillary beds
What is vasculitis?
inflammation of blood vessel
-causes changes in walls of blood vessels (thickening, weakening, narrowing, and scarring)
-restrict blood flow, resulting in organ and tissue damage
What is atherosclerosis?
thickening and hardening of walls of arteries caused by plaques of lipids, cells, and CT in tunica intima
Where is atherosclerosis frequently seen?
in arteries sustaining high blood pressure
What genetic defect is associated with atherosclerosis?
familial hypercholesterolemia
What are foam cells?
byproducts of macrophages trying to remove the cholesterol build up in arteries
What is often associated with atherosclerosis?
hypertension
-decrease vessel diameter and increase in systolic BP
What is an embolus?
when a piece of thrombus breaks off
What can an embolus cause?
acute ischemic event
-lack of blood flow
What can anoxia cause?
angina
What is the most common cause of ischemic heart disease?
atherosclerosis
What is gradual narrowing called?
stenosis
What is myocardial infarction?
when portion of the heart muscle dies
Can heart muscle cells regrow?
no, they are terminally differentiated so healing occurs via fibrosis
-causes loss in function
What is a stroke?
similar to MI, just in the brain
What is the result of a stroke?
cerebral infarct
-location of clot determines symptoms and severity
What do lymphatic vessels do?
conduct immune cells and lymph to lymph nodes
-remove excess fluid accumulated in interstitial spaces
-transport chylomicrons and lipid containing particles
The endothelial cells of lymph vessels are…
highly phagocytic
Are there valves in lymph vessels?
yes
Difference between lymph vessels and capillaries?
there are no red blood cells in lymph vessels
Where are lymphatic capillaries found?
in all tissues
EXCEPT- cartilage, bone, epithelia, CNS, and placenta
What does the lymph vascular system do?
drain excess fluid from ECS and return to blood stream
Why is lymph formed?
result of high hydrostatic pressure in arterioles; exceeds colloidal oncotic pressure exerted by plasma proteins
Characteristics of lymph nodes:
thin walled, lack blood, eosinophilic, proteinaceous fluid, and occasional WBC
Where does the lymph vascular system converge?
on thoracic duct and right lymphatic duct
When does lymph return to the blood stream?
at junction of L internal jugular vein and L subclavian vein
How is lymph movement controlled?
skeletal muscle contraction and body movement
immobility can lead to…
edema (swollen feet)
Intrinsic contraction for lymphatic drainage:
when vessels become expanded by lymph, the smooth muscle of the wall contract
Extrinsic contraction for lymphatic drainage:
external factors such as contraction of the surrounding muscles during exercise, arterial pulsation, and compression of tissues by forces outside the body
lymphedema
defect in transport of lymph because of abnormal vessel development or damaged lymphatic vessels
filariasis (elephantiasis)
parasitic infection of lymphatic vessels
-transmitted by mosquito bites
-in tropical countries
What are chylous ascites and chylothorax?
accumulation of high fat containing fluid or chyle in abdomen or thorax as result of trauma, obstruction, or abnormal development of lymphatic vessels
