Cardiovascular Flashcards
Define blood pressure
- the pressure that keeps the blood moving in the circulation (high on arterial side, low on venous side)
- the pressure exerted by the blood on the blood vessel wall
What is the equation for mean arterial blood pressure?
MABP = diastolic pressure + 1/3(systolic pressure - diastolic pressure)
How does ANP effect blood pressure?
decreases blood pressure by increasing urination, decreasing cardiac output, suppressing thirst, and vasodilation
What stimulates the release of ANP?
release from myocardial cells stimulated by atrial stretching due to increase venous return
How does ADH effect blood pressure?
increases blood pressure by decreasing urination, increasing cardiac output, and vasoconstriction
What stimulates the release of ADH?
decreased blood volume or blood pressure
How does Aldosterone effect blood pressure?
increases sodium retention by the kidneys, so increases blood volume and blood pressure
How does Angiotensin II effect blood pressure?
vasoconstriction, so enhances venous return, and increases blood pressure
If the radius of the vessel decreases, what happens to TPR?
What happens to blood pressure?
TPR will increase, and blood pressure will therefore increase
Explain the baroreceptor reflex when blood pressure is increased
- baroreceptor firing increases
- parasymp. stimulation increases: decreased heart rate
- symp. stimulation decreases: decreased contractility and decreased vasoconstriction
Explain the baroreceptor reflex when blood pressure is decreased
- baroreceptor firing decreases
- symp. stimulation increases: increased contractility and vasoconstriction
- parasymp. decreases: increased heart rate
Describe what happens when an animal goes from a lying position to a standing position
- gravity causes blood to pool in lower extremities (expanded veins)
- decreased venous return to heart, so decrease EDV, SV, and CO
- decrease in blood pressure
- baroreceptor firing decreases: symp. increases, parasymp. decreases
What is the starling equation?
What does each variable stand for?
Kf [(Pc + πi) - (πc + Pi)] Kf - hydraulic conductance Pc - capillary hydrostatic pressure πi - interstitial osmotic pressure πc - capillary osmotic pressure Pi - interstitial hydrostatic pressure
What happens when muscle tissue becomes more active?
- more pre-capillary sphincters relax, leading to more open capillary beds
- arteriolar vasodilation occurs, leading to more blood flow into the capillaries
- this leads to increased surface area and total volume, so diffusion and bulk flow increase
What factors effect lymph flow?
- myogenic effect of smooth muscle
- skeletal muscle pump
- one-way valves
- respiratory pump
What are the causes of edema?
- increase in capillary hydrostatic pressure
- decrease in capillary osmotic pressure
- increase in hydraulic conductance
impaired lymphatic drainage
What factors influence venous return?
- venous capacity
- bulk flow across capillary walls
- renin-angiotensin-aldosterone system
- sympathetic nervous system
- gravity
- skeletal muscle pump
- one-way valves
- respiratory pump
- cardiac suction
What is circulatory shock?
when blood pressure falls so low, that adequate blood flow to the tissues can no longer be maintained
What are the parameters and effects of Hypovolemic shock?
- hemorrhage, burns, surgery and trauma, and severe diarrhea and vomiting
- all lead to loss in blood volume
What are the parameters and effects of Vasogenic shock?
septic shock: endotoxin release by invading bacteria stimulate nitric oxide release from macrophages
- overproduction leads to vasodilation, decreasing TPR
anaphylatic shock: release of histamine
- vasodilation and increased permeability of capillaries
What are the parameters and effects of Cardiogenic shock?
heart failure, weakened heart muscles, decreases cardiac output
What are the parameters and effects of Neurogenic shock?
- decreased symp. activity leading to loss of vascular tone
- vasodilation which decreases TPR
What are the immediate compensatory measures for hemorrhage?
- vasoconstriction, venoconstriction, and increased heart rate
- due to increased symp. tone, angiotensin II, vasopressin, and epinephrine
What are the medium term compensatory measures for hemorrhage?
- movement of interstitial fluid into vasculature
- due to reduced capillary pressure, and increased interstitial fluid osmolarity
What are the long term compensatory measures for hemorrhage?
- recovery of fluid volume, plasma protein synthesis, erythropoiesis
- due to reduced urine output, increased fluid uptake, protein synthesis in liver, and erythropoietin production in kidneys
Describe the Renin-Angiotensin-Aldosterone System
- decrease blood pressure leads to decreased amount of O2 to kidneys
- stimulates release of Renin by kidneys, which converts angiotensinogen to angiotensin I
- angiotensin I is converted to angiotensin II
- angiotensin II goes to the adrenal cortex and stimulates the release of aldosterone, which increases sodium reabsorption in the kidney, increasing blood volume
- angiotensin II also causes vasocontriction in the blood vessels
