Session 5-Control Of Blood Pressure Flashcards
What is the equation for cardiac output?
CO=SV x HR
Cardiac output=stroke volume x heart rate
What is the mechanism for short term regulation of blood pressure?
Baroreceptor reflex
Which nerve endings are sensitive to stretch?
Those in the carotid sinus and aortic arch
True or false: decreased arterial pressure stretches baroreceptors
FALSE - increased pressure stretches
True or false: baroreceptor reflex works well to control acute changes in BP (up to 15 minutes)
TRUE
Why does the baroreceptor reflex not control sustained changes in BP?
The threshold for baroreceptor firing resets
What are medium and longer term controls of BP directed at?
Controlling sodium balance and thus extracellular fluid volume
What controls plasma volume?
Control of extracellular fluid volume - water follows sodium therefore controlling total body sodium levels controls plasma volume
What are the four neurohumoral pathways controlling circulating volume and therefore BP?
1) Renin-angiotensin-aldosterone system (RAAS)
2) Sympathetic nervous system
3) Antidiuretic hormone (ADH)
4) Atrial natriuretic peptide (ANP)
Which cells release renin?
Granular cells of juxtaglomerular apparatus (JGA)
Which factors stimulate renin release? (3)
1) reduced NaCl delivery to distal tubule
2) reduced perfusion pressure in kidney causes release of renin
3) sympathetic stimulation to JGA increases release of renin
Which reaction does renin catalyse?
Angiotensinogen -> angiotensin
Which enzyme catalyses the conversion of angiotensin I to angiotensin II?
Angiotensin converting enzyme (ACE)
How does angiotensin II affect the body? (3)
1) vasoconstriction
2) stimulates Na+ reabsorption at kidney
3) stimulates aldosterone from adrenal cortex which then stimulates no. 2)
What are two types of angiotensin II receptors?
Angiotensin 1 (AT1) Angiotensin 2 (AT2)
True or false: the main actions are via AT1 receptor which is a GPCR
TRUE
What action do the angiotensin II receptors have at the following sites:
1) sympathetic nervous system
2) hypothalamus
1) vasoconstriction
2) increases thirst sensation (stimulates ADH release-antidiuretic)
What are the actions of aldosterone? (4)
1) acts one principal cells of collecting ducts
2) stimulates Na+ and therefore water reabsorption
3) activates apical Na+ channel and apical K+ channel
4) increases basolateral Na+ extrusion via Na/K ATPase
What is the apical Na+ channel called?
ENaC (Epithelial Na Channel)
True or false: bradykinin, found in the lung, has vasoconstrictor actions
FALSE - vasodilator
What does angiotensin converting enzyme break bradykinin into?
Peptide fragments