Cardiovascular System Flashcards
cardiovascular system
left atrium and left ventricle
aorta
arteries
arterioles
capillaries
venules
veins
inferior/superior vena cava
right atrium and right ventricle
pulmonary artery
alveolar capillary network
pulmonary vein
tunica intima (inner layer)
consists of endothelial cells, connective tissue, and a basal layer of elastic tissue that separates the tunica intima from the tunica media
tunica media (middle layer)
characterized by the presence of layers of vascular smooth muscle cells and an elastin-rich extracellular matrix
tunica adventitia (outer layer)
consists primarily of fibroblasts, collagen, and nerve endings and is critical in the regulation of the dynamic lumen size
arterial tree
there are changes in the structural makeup of arteries throughout the arterial tree which is critical for organ perfusion and the delivery of nutrients to metabolically active tissues
conducting (elastic) arteries
characterized by layers of elastic fibers to adequately stretch to accommodate the blood surge with each ventricle contraction
conduit (muscular) arteries
characterized by many smooth muscle cells for adequate vasodilation and vasoconstriction to occur for blood delivery as needed
arterioles
consists of a tunica media that has no more than six rings of smooth muscle and a tunica adventitia that is similar in size
blood flow through the arteries is regulated by
blood pressure which is the pressure of circulating blood on the walls of blood vessels
maintenance of normal blood pressure is dependent on
the balance between cardiac output and peripheral vascular resistance
systolic blood pressure
indicates how much pressure your blood is exerting against your artery walls when the heart contracts
first Korotkoff sound
diastolic blood pressure
indicates how much pressure your blood is exerting against your artery walls while the heart is resting between beats
fifth Korotkoff sound
conducting and conduit arteries
have the highest blood pressure
thicker and more elastic to accommodate the higher pressure
arterioles
have a lower blood pressure
blood pressure regulation
autonomic nervous system:
vasoconstriction (increase BP)
increase in sympathetic input (epinephrine and norepinephrine)
vasodilation (decrease BP)
increase in parasympathetic (acetylcholine)
decrease in sympathetic input (epinephrine and norepinephrine)
renin-angiotensin-aldosterone system
nitric oxide
synthesized in response to shear stress by endothelial cells from arginine
attenuates sympathetic nervous system vasoconstriction to vasodilation to decreased blood pressure
hypertension
a condition in which the force against the artery wall is too high
primary hypertension
no identifiable cause of high blood pressure but tends to develop gradually over many years
accounts for 90-95% of hypertension cases
secondary hypertension
high blood pressure caused by an underlying condition which tends to appear suddenly
underlying conditions: obstructive sleep apnea, adrenal gland tumors, kidney disease, thyroid problems, congenital vascular defects, prescriptions drugs, illegal drugs
the development of hypertension is complex because of
the multiplicity of causal factors potentially implicated in its pathophysiology, including genetic, environmental, lifestyle, and metabolic factors as well as physiological vascular ageing
sympathetic over-activity causes damage to the vascular wall
increased collagen and decreased elastin result in increased vascular stiffness (increased blood pressure)
less elastic vessels cause the left ventricle to work harder to supply enough blood to the body
inappropriate activation of the renin-angiotensin system
increase in sodium and water reabsorption at the kidney when not necessary causing an increase in blood pressure
endothelial damage
increased blood pressure and therefore shear stress (friction) causes damage to the tunica intima
impaired secretion and/or activity of local vasodilating metabolites
capillaries
humans have about 2000-3000 capillaries per square millimeter of tissue
contains 6% of total blood volume
blood flow velocity relates inversely to cross sectional area
precapillary sphincters control blood flow into a specific capillary to meet metabolic requirements
at rest 1 of every 30-40 capillaries in skeletal muscle remains open
factors influencing relaxation of precapillary sphincter
increased blood pressure
intrinsic neural control
local metabolites produced during exercise
systemic venous vessels
serve as blood reservoirs as they contain 65% of total blood volume at rest
blood pressure declines in direct proportion to the resistance it encounters in the vascular circuit
venous return is therefore only possible because of valves
skeletal muscle pump
rhythmic action of muscular activity and consequent compression of thin veins contributes to venous return
active recovery cool-down
facilitates blood flow via skeletal muscle contraction through the venous system back to the heart
increased skeletal muscle blood flow by dilation
skeletal muscle blood flow closely couples to metabolic demands
open dormant capillaries
increase total muscle blood flow
deliver large blood volume with minimal increase in blood flow velocity
increase surface for gas and nutrient exchange
reduced blood flow to non-active tissue
increased sympathetic nervous system outflow
local chemicals that stimulate vasoconstriction
