carries blood to the glomerullus

surrounded by smooth muscle

carries blood filtered in the glomerulus back to the ret of the body. It carries back the formed elemetns.

surrounded by smooth muscle

A positive feedback when bp and volume in kidneys gets too low for filtration --> secretes renin

Forms a cuff-like arrangement of muscle cells at the point where each arteriole enters.

juxta(close to)glomerular(glomerulus)

It has 3 cellular components: mascula densa cells, extraglomerular mesangial cells, and granular cells.

Function as chemoreceptors or osmoreceptors. 

• Purposes:
• Allows more reapsorptionof Na and Cl, less reabsorption of NaCl in the ascending loop so less NaCL conc. at mascula densa
• Decreases resistance to blood flow in the A arterioles which increases glomerular hydrostatic pressureand in turn returns GFR to normal
• increases renin release from juxtaglomerular cells

Responsible for the production and secretion of renin involved in the renin-angiotensin system.

In afferent and afferent arteriole, enlarged smooth muscle cell.

Have phagocytic and contractile properto to apropriately filter.

Influences capillary function

vasopressin/angiotensin II affect mesnagial cell contraction

when cells are relaxed, surface area is maximal

when cells constrict, less surface area

When  the number substances to be absorbed exceeds the amount of carriers in the tubules needed to take out the substances.

Actively absorbed compounds are impacted by the number of carriers in the tubules that are available.

reabsorption of Na and Ca

secretion of drugs, ammonia, acids, and toxins

rebsorption of water (save best/most imp for last) and Na

secretion of acids, ammonia, drugs, and toxins

Cuboidal cells with microvilli

Cuboidal because things are being secreted and microvillik because of reabsorption.

Also the preence of vaculoue separate the proximal from distal tube.

squamous in thin ascending (good for releasing things for reabsorption)

 cuboidal in thick ascending

cuboidal cells with much fewer microvillie than the proximal tubule

(cuboidal for reabsorption)

mainly columnar cells, cuboidal as well.

Because it is carrying substances away.

Collecting ducts are characterized by clear-staining cytoplasm and a defined cell border.

• Wrap around the glomerular capillary.
• Podocyes confer size selectivty of the filtrates from its many cell-surface proteins which ensure tha tlarge proteins remain  in the bloodstream and don't pass through.
• Podocytes also help regulate glomerular filtration rate, when podocyes contract they cause closure of the filtration slits thus decreasing the GFR
• Have a high endocytic activity (process by which cells absorb molecules) due to many coated vesicles and pits, a large number of mulivesicular bodies and othe lysosomal components.
• They also contain an ER and a large Golgi apparatus, indicative of a higih capcity for protein synthesis and post-translational modifications
• "Pedicels" (or "foot processes") extend from the podocyte and increase the surface area.

Filter that lies between the blood and the interior of the glomerular capsule

Layers:

• Fenestrated capillary endothelium - of the glomerular capillaries
• basement membrane - composed of fused basal laminae of the otherlayers, restricts all but the smallest proteins
• Visceral membrane - of the glomerular capsule (podocytes)

• Change diameter of afferent arteriole (increasing the diamter increases GFR)
• Change diameter of efferent arteriole (decreaseing the diameter increases GFR)
• Change podocyte permeability
• Alter blood pressure
• Capsular Hydrostatic Pressure and Blood Colloidal Osmotic Pressure decrease GFR

Why does filtrate osmolarity increase from 300 mOsm in the proximal tubule to 1200 mOsm after the descending Loop of Henele.

Where is the fitlrate most concentrated in a nephron?

Where is it least concentrated?

most concentrated - at the end of the descending Loop of Henle (b/c H₂O is being reabsorbed out)

least concentration - after ascending Loop of Henle (b/c NaCl is being reabsorbed out)

maintains adequate gfr despite changes in bp and blood flow

smooth muscle cells: afferent and efferent arteriole feedback mechanisms - mechanorecetpor

tubular mechanism: distal tubule filtrate

Renin-Angiotensin System

increases/restores gfr by increasing bp

Renin, produced by juxtaglomerular cells, enzymatically changes aniotensinogen to angioten I. Aniotensin I travels to the lungs where it is converted to angiotensin II by the enzyme ACE. Angiotensin II is a vaoconstrictor - blood ressure rises. It's secretion stimulates - increases secretion of ADH, stimulates the adrenal cortex to produce aldosterone , and stimulates the hypothalamus to activate the thirst reflex all of which increases bp.