Malpas Flashcards
What is the relationship between regulation of blood volume and blood osmolarity?
Blood osmolarity is controlled through the regulation of blood volume rather than solute concentration as osmolarity controls blood volume
What is effective circulating volume?
It is a physiological concept of blood volume not an anatomical compartment which allows it to be changed quickly by cardiovascular changes
What are the behavioural changes mediated by changes in blood volume?
Osmoreceptors in the brain detect osmolarity, they increase their activity with an increase in osmolarity. An increase in activity stimulates thirst and ADH release
What are the cardiovascular changes mediated by changes in the blood volume?
Changes are detected by baroreceptors or atrial stretch receptors or carotid bodies these all increase their signalling to the CNS with an increase in blood pressure/volume. This afferent signal is inversly proportional to SNA activity and through changes in vascular tone and heart rate will restore blood pressure but NOT blood volume
What are the renal changes mediated by changes in blood volume?
Changes in blood volume will induce a change in blood pressure and then a further change in GFR and tubular flow, which is inversely proportional to the amount of renin released. Renin controls the levels of angiotensin I, II and aldosterone These combine to control vascular tone and salt retention to regulate blood VOLUME
What is the neuronal signalling pathway for the baroreceptors?
Baroreceptors fire an afferent signal through their vagal nerve, to the Nucleus tractus solirail, this then signals either the Caudal Ventrolateral Medulla which signals the ventrolateral medulla to increase SNA
OR the N. Ambigous which regulates vagal nerve activity
What is the purpose of the baroreceptor reflex?
To maintain a constant blood pressure and by extension a constant perfusion pressure in the tissue through changing heart rate
What is the role of aldosterone?
Reduce Na secretion and increase reabsorption
What is the role of Angiotensin II?
Decrease Na secretion and mediate vasoconstriction
What is the role of ADH?
To increase water reabsorprtion
What is the role of Renin?
To decrease Na secretion
What is the role of Atrial Natriuretic peptide?
Increase Na Secretion
What role does the CNS have in vascular resistance?
Can allow blood to be redirected to flow to prioritized organs
