The Kidney: Filtration, Reabsorption and Secretion

Label this image to describe the gross anatomy of the kidney.

Label this image to show the functional unit of the kidney - the nephron.

Label this image to show the anatomy of the renal corpuscle.

Why do capillaries in the glomerulus have relatively high permeability?

Label this image to show the cells surrounding a glomerular capillary.

The basement membrane of the glomerulus has fixed anions throughout.

The branching processes of the podocytes make contact with those neighbouring them.

Which proteins listed here are responsible for the joining of podocyte foot processes to contibute towards filtration?

How does nephrin between the podocyte foot processes contribute towards filtration?

Which cells of the juxtaglomerular apparatus have smooth muscle properties that change the surface area of the basement membrane?

What is the function of the granular juxtaglomerular cells?

Which cells of the juxtaglomerular apparatus detect sodium concentration of the fluid in the ascending loop of Henle?

What do we describe the peritubular capillaries as in relation to the loop of Henle?

Glomerular filtration is passive.

What is true of the relationship to glomerular filtration of molecular size?

What is true of the relationship between glomerular filtration and molecular charge?

Glomerular filtration rate is the [blank_start]volume[blank_end] of fluid filtered from glomeruli per [blank_start]minute[blank_end]. It is measured in [blank_start]ml[blank_end]/[blank_start]min[blank_end]. GFR depends on [blank_start]Starling[blank_end] force, the [blank_start]surface area[blank_end] of the filtration interface and the [blank_start]permeability[blank_end] of the capillaries. It is regulated by both [blank_start]neural[blank_end] and hormonal input.

Fill in the blanks to describe the four Starling forces that contribute towards glomerular filtration rate. The [blank_start]hydrostatic[blank_end] pressure of the capillaries is [blank_start]higher[blank_end] than the [blank_start]hydrostatic[blank_end] pressure of the Bowman's space. Thus, fluid is inclined to move [blank_start]out of[blank_end] the capillaries. The [blank_start]colloid oncotic[blank_end] pressure in the capillary is [blank_start]higher[blank_end] in the capillaries than in the Bowman's capsule. Thus, fluid is inclined to move [blank_start]into[blank_end] the capillaries. Despite this, the net glomerular filtration pressure is [blank_start]positive[blank_end], so fluid moves [blank_start]out of[blank_end] the capillaries.

If we constrict the afferent arteriole... We [blank_start]reduce[blank_end] the hydrostatic pressure in the capillaries and [blank_start]decrease[blank_end] GFR. If we dilate the afferent arteriole... We [blank_start]increase[blank_end] the hydrostatic pressure in the capillaries and [blank_start]increase[blank_end] GFR. If we constrict the efferent arteriole... We [blank_start]increase[blank_end] the hydrostatic pressure in the capillaries and [blank_start]increase[blank_end] GFR. If we dilate the efferent arteriole... We [blank_start]reduce[blank_end] the hydrostatic pressure in the capillaries and [blank_start]decrease[blank_end] GFR.

Which nervous system innervates the glomerular mesangial cells covering the capillaries?

How do we increase glomerular filtration rate by changing the surface area of the filtration interface?

Secretion is the movement of solutes from the peritubular capillaries into the tubules AND the movement of molecules from the wall of the tubule directly into its lumen.

Fill in the blanks below to describe the secretion of organic acids (anions) into the tubule. 1. Organic anion enters tubule epithelial cell from blood in exchange for [blank_start]dicarboxylate[blank_end] via an [blank_start]ATP[blank_end] dependent organic anion transporter (OAT). 2. [blank_start]Dicarboxylate[blank_end] accumulates in cell by [blank_start]metabolism[blank_end] and the action of [blank_start]Na+[blank_end] coupled transport to drive this co-transport. 3. The organic anion enters the tubule lumen via [blank_start]ATP[blank_end]-dependent transporters.

What molecule do organic acids (anions) enter the tubule epithelial cells with from the blood in secretion?

What transporters do organic cations enter the tubule epithelial cells via?

Which ions do organic bases enter the tubule lumen in exchange for during secretion?

Which transporters do organic bases (cations) enter the tubule lumen via?

Reabsorption occurs in the [blank_start]proximal tubule[blank_end]. The epithelium here is [blank_start]simple columnar[blank_end] and has a [blank_start]brush-border[blank_end] to increase surface area. This epithelium is dense in [blank_start]mitochondria[blank_end] to supply primary and secondary active transporters. The tubule has [blank_start]Na+[blank_end] coupled cotransporters, a [blank_start]tubular maximum[blank_end] system whereby the membrane can be saturated and specific transporters for [blank_start]glucose[blank_end] and amino acids respectively.

How are glucose, amino acids, phosphates and sulphates reabsorbed?

How are urea, chloride, potassium and calcium ions reabsorbed?

FIll in the blanks below to describe the reabsorption of glucose in the proximal tubule. 1. Glucose is taken up via [blank_start]sodium[blank_end]-dependent glucose co-transporters (SGLT) on the [blank_start]luminal[blank_end] membrane. 2. The [blank_start]GLUT[blank_end] facilitated transporters on the [blank_start]basal[blank_end] membrane allows [blank_start]facilitated[blank_end] diffusion into the capillaries upon binding of [blank_start]glucose[blank_end]. 3. The Na+/K+ [blank_start]ATPase[blank_end] maintains a [blank_start]concentration gradient[blank_end] of sodium by moving sodium out of the cell into the [blank_start]capillary[blank_end].

Why is there a renal threshold of glucose reabsorption?

The transporters required for reabsorption of amino acids in the tubule are specific to their properties (uncharged, acidic, basic etc)

How many sodium-dependent amino acid transporters are there?