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Lecture 17

BIO310H5 Lecture Notes - Lecture 17: Macula Densa, Afferent Arterioles, Juxtaglomerular CellPremium

2 pages123 viewsFall 2018

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Nagham Abdalahad

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BIO310 Lecture 17
Juxtaglomerular Apparatus
Macula densa cells: Chemoreceptors (monitor [Na+ ]) ,
also detect rate of flow of filtrate in DCT (act to cause
vasoconstriction/vasodilation of afferent arteriole)
Juxtaglomerular cells (granular cells) in wall of afferent
arteriole: Baroreceptor (monitors pressure) and releases
Sympathetic innervation: Stimulates JGA cells to
release renin (direct effect) or causes vasoconstriction of
the afferent arteriole which drops pressure and leads to
renin release (indirect effect).
Renin liberated into blood in response to:
1 Drop in plasma Na+ concentration (monitored by macula densa cells)
2 Local stimuli - loss of distension, ie. Drop in blood pressure
3 Circulating catecholamines
Renin-Angiotensin System
Antidiuretic hormone(ADH)/vasopressin
ADH regulates water permeability in the collecting duct -is secreted by
hypothalamic neurons at the posterior pituitary
Factors regulating ADH secretion
Major: osmoreceptors in the brain & cardiovascular baroreceptors
Other: Angiotensin II stimulates ADH release & ANP inhibits ADH
Regulation of Blood Volume
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