Cardiovascular Physiology 4 Arterial Pressure Cardiovascular Disease Flashcards
what happens to hydrostatic pressure in the capillary if flow in > flow out
increases
what is the function of the arterial system and its regulation
keep MAP constant
-regulation: systemic
what is the flow out of the arterial system controlled by
TPR
what is the flow into the capillary system controlled by
resistance of tissue arteriole
what is the function of the capillary system
deliver O2 and nutrients, pick up CO2 and other metabolic waste
what controls the capillary system
local (active hyperemia)- match tissue blood flow to tissues metabolic activity
what is the flow to tissues in the capillary system controlled by (formula)
F tissue= MAP/R of tissue arteriole
what is the flow out of the capillaries dependent on
venous pressure
what is the function of the venous system
-peripheral venous pressure
- venous return
what is the regulation of the venous system
systemic
what does the baroreceptor reflex respoond to
changes in blood volume and/or MAP
what does a decrease in blood volume do to Venous pressure ,VR, atrial pressure, EDV, SV,CO and BP
decreases everything
describe the baroreceptor reflex
-stimulus: change in MAP
-reflex receptor: baroreceptors
-afferent pathway: visceral sensory neurons
-integrating center: medullary CV control centers in medulla oblongata (brainstem)
-efferent pathway: autonomic motor neurons
-effectors: cardiac muscle (AR and contractile cells), arteriolar smooth muscle, venous smooth muscle
-effector response: change rate and force of contraction (CO), change arteriolar resistance (TPR), change venous tone (VR -> EDV -> CO)
-feedback regulation: negative
what is happening with the sympathetic and parasympathetic nervous systems during the baroreceptor reflex
-decrease in sympathetic outflow to heart, arterioles, veins
- increase in parasympathetic outflow to heart
where are baroreceptors located
mainly aortic arch and carotid arteries but also large systemic veins, the pulmonary vessels, and the walls of the heart
what are the functions of the baroreceptor reflex
- immediate changes to restore MAP to homeostatic level
- allows time for other mechanisms to occur to eliminate disturbance
what happens to the baroreceptor reflex with prolonged increased MAP over time
adapt overtime and decrease rate of firing
-reflex functions around a higher than normal setpoint
how does high arterial pressure regulate blood volume? how does low blood volume negatively inhibit arterial pressure
decreases it
-acts on kidneys to increase excretion of water and sodium
negative feedback by acting on cardiac muscle to decrease CO, SV< EDV, VR, and VP
how does high blood volume regulate arterial pressure? how does arterial pressure negatively inhibit high blood volume
increases it
-acts on cardiac muscle to increase VP, VR, EDV, SV, and CO
negative feedback by increasing kidney excretion of water and sodium
what are some other stimuli that increase MAP
-decreased arterial [O2]
-increased arterial [CO2]
-decreased brain blood flow
-pain originating in skin
- stress
-anger
-eating
- sexual activity
what are stimuli that decrease MAP
-pain originating in viscera or joints
- sleep
-happy mood
what are the 4 causes of hypotension
-hemorrhage
-shock
- orthostatic
- other causes
what are the RAPID compensatory mechanisms for hemorrhage and explain each
- baroreceptor reflex: returns MAP toward normal, increases CO and TPR
- autotransfusion: movement of ISF, arteriolar constriction causing decreases Pc, net absorption of fluid into capillary
what is the LONG TERM compensatory mechanism of hemorrhage and describe each
-endocrine system: ANGII, aldosterone, ADH, erythrothropoietin
-behavior: thirst and consumption of water
what is shock
a condition in which there is inadequate blood flow to meet tissue needs
what are the 3 types of shock
-hypovolemic shock
- vascular shock
- cardiogenic shock
what is hypovolemic shock and what are the causes
-most common, results from a large loss of blood
-causes: hemorrhage, severe vomitting, severe diarrhea, and extensive burns
what is vascular shock and what are the causes
-blood volume is normal but circulation is poor due to abnormal expansion of the vascular bed caused by extreme vasodilation. huge drop in TPR leads to a drop in MAP
-causes:
anaphylaxis- loss of vasomotor tone due to allergic reactions
neurogenic shock- loss of autonomic control
septic shock- loss of vasomotor tone due to infections in the blood stream
what is cardiogenic shock and what are the causes
- this is pump failure, the heart can not sustain adequate circulation
-causes: myocardial damage following a severe MI or multple MIs
what is orthostatic hypotension and what is it causes by
-drop in MAP upon standing
-cause: effects of gravity cause a decrease in VR -> decrease in EDV -> decrease SV -> decrease CO -> decrease in MAP
what are the effects of training of cardiac performance
heart accomplishes same amount of work with less beats
what is hypertension defined as
chronically elevated MAP
why is hypertension a silent killer
most people dont know they have it until it has caused significant damage
what are the two forms of hypertension and what is the incidence and cause of both
-primary (essential) hypertension- 90%- idiopathic
- secondary hypertension- 10%- secondary to disease state. can be treated by treating disease
what are factors that are involved in the development of hypertension
-diet: high sodium, cholesterol
obesity
-age (signs appear around 40 y/o)
-gender (males> females until menopause)
-DM
- genetics (runs in families, black more prevalent than whites)
- stress
-smoking
what are the diseases associated with secondary hypertension
-tumor of the adrenal medulla (excess EPI)
- cushings disease (glucocorticoid excess)
-atherosclerosis of the renal arteries (RAS)
- renal hypertension (kidney disease)(RAS)
-arteriosclerosis
- hyperthyroidism (TH excess)
what are the treatments for hypertension
-diuretics
-beta-adrenergic receptor blockers (beta blockers)
- calcium channel blockers
- renin angiotensin aldosterone system inhibitors/blockers
-sympathetic nervous system modulators
what are the two pharmacologically relevant alpha receptors for hypertension and what to they do and where are they located
-alpha 1- peripheral receptor - stimulate VSM to contract
- alpha 2- central receptor- inhibit NE and EPI secretion
what are the two types of vascular remodeling in hypertension
inward eutrophic remodeling and hypertrophic remodeling
what happens in inward eutrophic remodeling
-small vessels that constrict in response to increased MAP
- VSM growth around narrowed lumen
- no change in total cross sectional area of vessel
what happens in hypertrophic remodeling
-large vessels that do not constrict in response to increased MAP
-size of VSM cells increase
-increase in EC matrix proteins to support wall
-increase in total cross sectional area of vessel
- makes large vessels stiffer (less compliant)
what are the 2 types of flow in vessels
laminar flow and turbulent flow
what can turbulent flow cause
- damage to endothelial cells and plaque development in wall of BV
- bruits and murmurs
-increases friction and the energy required to drive flow - increases the possibility of thrombotic events
when does laminar flow occur
when vessels are straight, endothelium is healthy, and smaller vessles
where is the velocity of flow greater in laminar flow in the BV
in the center of the vessel compared to the outside
describe the type of laminar flow
parabolic profile of flow
what is shear in laminar flow and what can it cause
when adjacent layers of blood move at different velocities- can break up RBC aggregates
what is reynolds number (Re)
the calculation of the tendency for turbulent flow
what does it mean if Re is greater than 2000
flow is mostly likely turbulent
what does it mean if Re is greater than 3000
always turubulent
what causes turbulent flow
increased velocity of blood flow, increased diameter of vessel, increased density of blood, decreased viscosity of blood (hematocrit)
what is heart failure (CHF) defiend as
heart fails to pump adequate CO
what are the two types of CHF
-diastolic dysfunction
-systolic dysfunction
what happens in diastolic dysfunction
-ventricles have reduced compliance
-creates problems with ventricular filling
-reduced EDV
what is the most common cause of diastolic dysfunction in CHF
hypertension- ventricular hypertrophy
what happens in systolic dysfunction
-ventricle has reduced contractility
-decreased SV at any given EDV
what is the most common cause of systolic dysfunction
myocardial damage as a result of myocardial infarct
what are the treatments for CHF
-diuretics
- beta blockers
- cardiac inotropic drugs
- renin-angiotensin-aldosterone system inhibitors/blockers
why does systemic Pc increase during right heart failure and not during left heart failure
accumulation of volume in systemic criculation
what type of heart failure is pulmonary edema seen in
LHF
what does the baroreceptor reflex do
alters Co and TPR to restore MAP to homeostatic levels
what system mediates the baroreceptor reflex
the nervous system
how fast is the baroreceptor reflex
short term response (minutes to hours)
can the baroreceptor reflex override local control
yes
