Renal Anatomy
Nephron Anatomy
Hormones
Filtration
Reabsorbtion
100
What are the green structures in this image? What are their Purpose?
The renal pyramids exist to reabsorb water in the kidney.
100
What structure(s) are pictured here?
The renal corpuscle, including the Bowman's Capsule, Glomerulus, and arterioles
100
Antidiuretic hormone (ADH/AVP/Vasopressin) has what effect on micturation? How does it acheive this effect?
ADH causes freely available aquaporins to be deposited in the nephron, mainly on the principle cells in the collecting ducts.
100
What parts of blood do not filter through the filtration membrane (what stays in the blood)?
Cells, proteins, other large molecules
100
Where are glucose, amino acids, and most other valuable nutrients reabsorbed? How are they reabsorbed?
Mostly primary (with ATP) and secondary (cotransport) active transport in the proximal convoluted tubule PCT.
200
What is this structure, colored green called? What is it's purpose?
The renal cortex is the main site of filtration and accounts for the majority of filtrate reabsorption.
200
This structure is responsible for reabsorbing the majority of the filtrate.
The Proximal Convoluted Tubule (PCT)
200
Norepinephrine (NE) is a neurohormone released by the sympathetic nervous system. When released onto the kidneys, What effects does it have?
It constricts the afferent and efferent arterioles, which significantly reduces renal blood flow and lowers the glomerular filtration rate. It also triggers the release of renin, activating the Renin-Angiotensin-Aldosterone System. This can regulate water volume. NE also acts on the micturition reflex to prevent micturation.
200
What is the main waste product excreted by the kidneys?
Urea, Creatinine
200
What would happen to a person if their renal medulla was isotonic to filtrate in the descending loop?
If the concentration of the interstitial fluid in the renal medulla was isotonic to that of the filtrate, no water reabsorption would occur. They would urinate much more frequently, and would likely become dehydrated (polyuria).
300
What are these green structures called?
Renal Papillae are the exit points of the renal medulla that funnel filtrate into the calyces of the kidney.
300
This structure is responsible for water reabsorption.
The nephron loop/loop of henle
300
Aldosterone is a hormone secreted by the adrenal glands. What does it do? What triggers its release?
Aldosterone is a nonpolar (lipid soluble) mineralocorticoid hormone that acts as the body's primary regulator of blood pressure and electrolyte balance. Its release is primarily triggered by Angiotensin II. Aldosterone acts on the principle cells of the collecting duct by increasing transcription of ion transporters which will pump ions into the interstitial space, obligin water to follow, where it can then diffuse into the blood via the peritubular capillaries.
300
Why do carnivores tend to have more concentrated urine than herbivores?
Carnivores eat meat which is higher in protein. Protein catabolism produces more waste products than that of sugars, lipids, or nucleic acids. Carnivores therefore has more urea and creatinine to excrete and thus have more concentrated urine.
300
What would happen to a person if their ascending loop was impermeable to ions?
The renal medulla would have a lower than usual tonicity relative to the filtrate, causing less water to be reabsorbed. Furthermore, electrolytes would have less opportunities to be reabsorbed leading to electrolyte imbalances such as hypokalemia and hyponatremia.
400
What are invaginations of the renal cortex into the renal medulla called?
Renal columns
400
This structure acts to regulate the ph of the blood and fine tunes the electrolyte concentration of the filtrate based on electrolyte levels in the blood.
The distal convoluted tubule
400
Renin is a chemical messenger secreted by the juxtaglomerular apparatus of the kidneys. How do the kidneys "know" to release renin, and how does renin act to solve this problem?
The kidneys monitor blood pressure through the juxtaglomerular apparatus, which triggers renin release in response to low arterial pressure, decreased sodium levels, or sympathetic nervous system activation. Once secreted, renin acts as an enzyme that initiates the Renin-Angiotensin-Aldosterone System (RAAS) by converting hepatic angiotensinogen (which is always present in the blood) into angiotensin I. This is further converted by angiotensin converting enzyme (ACE [produced in the lungs]) into angiotensin II, a potent vasoconstrictor that narrows blood vessels to increase pressure and stimulates the adrenal glands to release aldosterone. This decreases blood flow around the kidneys and increases pressure.
400
If blood pressure increases, what would happen to glomerular filtration rate (GFR) in the absence of any homeostatic response?
It would increase as higher pressure would push blood across the filtration membrane.
400
Notomys mitchellii, a species of Desert hopping mice, have nephron loops 5.2 mm long! Human nephron loops are around 2.2 mm long.
Why does the desert mouse have such long nephron loops?!
What would you expect of a beavers nephron loops?
These mice evolved longer nephron loops because the water-scarce environment of the desert acted as a selection pressure for water conservation, which longer nephron loops facilitate by allowing more opportunities for water to be reabsorbed.
Beavers live in freshwater lakes and rivers, and thus have little need to reabsorb water. As a consequences they evolved fairly short nephron loops which often don't even reach into the renal medulla.
500
Located on the concave medial margin of the kidney, this structure is where blood vessels and the ureter interface with the kidney.
The Renal Hilum
500
This specialized structure, nestled between the afferent arteriole and the distal convoluted tubule, regulates blood pressure by secreting the enzyme renin in response to low sodium levels or a drop in blood volume.
The juxtaglomerular (next to the glomerulus) apparatus.
500
What would happen if a patient possessed a genetic mutation that renders the cells of the ascending limb of the loop of Henle impermeable to sodium ions? What would be the downstream effects of this on the patient as a whole? Why?
If the ascending limb is impermeable to sodium, the kidneys cannot create a high-concentration osmotic gradient in the medulla. Loss of the medullary gradient prevents the collecting ducts from reabsorbing water, resulting in the production of large volumes of dilute urine and severe dehydration. Consequently, the patient would suffer from profound electrolyte imbalances and chronically low blood pressure due to the inability to maintain fluid volume.
500
What homeostatic mechanisms exist to maintain the GFR?
The body regulates GFR through five mechanisms: the Myogenic Mechanism, Tubuloglomerular Feedback (TGF), the Renin-Angiotensin-Aldosterone System (RAAS), the sympathetic nervous system (Norepinephrine), and Atrial Natriuretic Peptide (ANP).
500
Matthew Carrington’s 2005 death is the most prominent case of hazing-induced water intoxication, caused by forced ingestion of massive quantities of water during a fraternity ritual.
Speculate as to the potential consequences of water intoxication.
Why or why wouldn't a drug that blocks ion pumps in the ascending loop work as a treatment for this conditions?
Fatal cerebral edema and seizures. In such emergencies, a loop diuretic like Furosemide is the standard treatment; it works by blocking the na/k/cl2- cotransporter in the Loop of Henle.