BIPN 100 Lecture Notes - Lecture 26: Renal Corpuscle, Distal Convoluted Tubule, Proximal Tubule
13 Jun 2018
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BIPN 100 Lecture 26
6/6/2018
• The nephron is the functional unit of the kidney
•
• Real orpusle is here filtratio happes gloerulus ad Boa’s apsule
• Filtratio is oeet of fluid fro gloerulus ito Boa’s apsule, ad oe it
enters the ephro, it’s alled filtrate
• Filtrate and blood plasma have very similar compositions, they are isosmotic
• Renal tubule is the proximal tubule, loop of Henle, and distal tubule
• Proximal tubule
o Where most of the reabsorption happens
o In the cortex
o 300 mOsm filtrate
• Descending limb of the loop of Henle
o Permeable to water
• Ascending limb of the loop of Henle
o Impermeable to water
o Permeable to solutes
• Loop of Henle goes deep into the medulla
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• Distal tubule
o In the cortex
o Can reabsorb water and certain solutes depending on hormonal regulation
• Collecting duct
o Can reabsorb water and certain solutes depending on hormonal regulation
• Distal nephron= distal tubule + collecting duct
•
• Capillary pressure causes filtration
o Filtration across the walls of the glomerular capillaries is caused by hydrostatic
pressure (capillary blood pressure PC)
o Opposed by:
▪ Capillary colloid osmotic pressure (capillary oncotic pressure)
▪ Fluid pressure reated fluid i Boa’s apsule apsule fluid
pressure)
• Glomerular filtration rate (GFR)
o Is the amount of filtrate formed in both kidneys every minute
• The afferent arteriole has a large radius than the efferent arteriole, which helps to
maintain a high capillary hydrostatic pressure
o Net filtration pressure resulting is ~10 mmHg
• Resistance in the afferent and efferent arterioles is the easiest way to change the GFR
• Vasoconstriction of afferent arteriole, efferent remains unchanged
o Most of the blood flow that would have gone to the kidney will go to other
organs
o Capillary pressure decreases because a smaller amount is going in, while the
output remains the same (due to no change in the efferent arteriole)
o There is a decreased PC
• Increased resistance in the efferent arteriole
o Same goes in, less comes out of the arterioles, causing increased capillary
pressure
o Decreases renal blood flow but increases hydrostatic pressure and GFR
• Afferent arteriole dilating
o Decreased resistance in afferent arteriole
o Efferent arteriole remains the same
o Causes a GFR increase due to increased capillary pressure
• Sodium reabsorption
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
In the cortex: 300 mosm filtrate, descending limb of the loop of henle, permeable to water, ascending limb of the loop of henle. Impermeable to water: permeable to solutes, loop of henle goes deep into the medulla, distal tubule. Inhibitory interneuron before the a-alpha motor neuron releases ach which binds to nicotinic muscle cholinergic receptors on the motor end plate of the skeletal muscle sphincter. If threshold is reached, contraction and constriction will happen: at the same time, another interneuron tells a parasympathetic neuron to release ach into nicotinic neural cholinergic receptors on the postganglionic sympathetic neuron. It then releases ach onto the smooth (cid:373)us(cid:272)le of the (cid:271)ladder (cid:449)all. A(cid:272)h is e(cid:454)(cid:272)itator(cid:455) i(cid:374) s(cid:373)ooth (cid:373)us(cid:272)le (cid:894)it"s a muscarinic 3 cholinergic receptor). Activates a conduction pathway that causes contraction of the smooth muscle, squeezing the bladder: all this leads to peeing, kidneys are the main route for water and ion removal.
