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Flashcards in Intro to Kidney Deck (47):

What does the kidney do?

-REGULATION of water and electrolyte balance (input = output) and blood pressure -EXCRETION of metabolic wastes, bioactive substances -MAKES red blood cells, vitamin D


How do kidneys respond to us VARYING how much water and electrolytes we take in?

kidneys respond by VARYING the amount of WATER CONTENT in MINERALS in the URINE we put out of our body- this is HOW kidneys maintain HOMEOSTASIS!


Why do our kidneys excrete metabolic waste?

Our bodies continuously form metabolic waste. Not all products of metabolism are useful (=NONFUNCTIONAL) or good for us. Some end products don't serve a useful function and in HIGH CONCENTRATIONs, they are even HARMFUL.


What are some examples of metabolic waste our kidneys excrete?

Urea (from proteins) Uric Acid (from nucleic acids) Creatinine (from Muscle creatine) Hb breakdown products Metabolites of various hormones (from endocrine system


What are examples of bioactive substances our kidneys excrete?

drugs (actively AND passively excreted), hormones (removed in parallel from the blood by kidneys too)


What does blood pressure ultimately depend on?

Blood volume


How do Kidneys regulate blood volume?

by maintaining sodium and water balance to regulate blood volume AND releasing VASOACTIVE substances to actively REGULATE SMOOTH MUSCLE in peripheral blood vessels


How do the kidneys regulate red blood cell production? And, how is secretion regulated?

by: 1. releasing erythropoietin (EPO) AND 2.controlling red blood cell production in bone marrow *Partial pressure of oxygen in the kidneys regulates how much EPO it makes and releases


What's the pathway by which sunlight on skin is turned into a substance that the kidney makes to maintain calcium balance in body? And the pathway for dietary intake?

7-Dehydrocholesterol pathway: Sunlight on skin produces 7-Dehydrocholesterol into Cholecalciferol (vitamin D3) goes into LIVER to produce 25-hydroxyvitamin D3 goes into KIDNEY to make 1,25 DiHydroxyvitamin D3 Dietary intake: eat fish, meat (vitamin D3), supplements (D2) goes to LIVER which turns it into 25,hydroxyvitamin D3 which the KIDNEY turns into 1,25 dihyrdoxyvitamin D3


What substance does the Kidney make from Vitamin D precursors or vitamin D from our diet to maintain calcium balance in the body?

1,25-dihydroxyvitamin D3


The CNS can only use _______ for energy!



When we don't eat carbs, how does our body make new glucose? How does this help with maintaining acid-base homeostasis?

kidneys make glucose from non-carb sources so from amino acids and glycerol!


When we don't eat carbs, how does our body make new glucose? How does this help with maintaining acid-base homeostasis?

kidneys make glucose from non-carb sources so from amino acids (ammonioagenesis) and glycerol! key pt: Kidney ammonioagenesis is critical to maintaining acid-base homeostasis!


What is the renal corpuscle?

It's a compact bunch of interconnected capillary loops, surrounded by a hollow capsule. It includes bowman's capsule and the glomerulus. Arterioles carry blood to Bowman's capsule. There's a fluid filled space within Bowman's capsule that filters blood!


Where does most reabsorption happen in the nephron?

in Proximal Tubule! The proximal tubule is made of 2 segments: 1. proximal CONVOLUTED and 2. proximal STRAIGHT tubule


What's the pathway by which the Kidneys filter blood? PUTTING THINGS TOGETHER

things go into Bowman's capsule, are drained from there into proximal tubule


What is the area between the Loop of Henle and the Distal Tubule called?

Macula Densa


What creates and maintains an osmotic gradient in the medulla?

Loop of Henle


What makes up the loop of henle?

thin and descending and ascending limbs and thick ascending limb


What is a continued area of reabsorption and regulation?

distal tubule


What's the last part of an independent nephron?

collecting duct


What is the part of a nephron that concentrates things?

collecting duct


Where can you find homogenous cells in the nephron?

within each structure before the distal convoluted tubule


What are the 2 types of cells found in the distal tubule?

principal (aka "primary") cells intercarlated cells (alpha + beta)


What is the only part of the nephron that has a heterogenous cell population within a nephron segment?

distal tubule


What are the different types of/populations of nephrons?

Outer Cortical (Superficial) which have capillaries = 80% of nephron Juxtamedullary (Deep) which have vasa recta = 20% of nephron


Does the Kidney have more cortical than juxtamedullary nephrons?



What is the most important difference between cortical and juxtamedullary nephrons?

length of loop of henle! (but they also differ in location and length of other segments which lead to different results)


Can you trace the renal blood flow pathway?

Renal artery to segmental to interlobar arteries to arcuate arteries to interlobular (cortical radial arteries) to afferent arteriole (site of regulation) to glomerulus (glomerular capillaries) to efferent arteriole (NOT venule) to either peritubular capillaries to venule to veins


Where can you find peritubular capillaries?

cortical efferent arterioles are distributed


What is normal renal blood flow?

20% of Cardiac Output = 1 L/min Filtered by glomerulus (blood flows through AFFERENT and leaves through EFFERENT arterioles)


What is normal renal blood flow (RBF)?

20% of Cardiac Output = 1 L/min Filtered by glomerulus (blood flows through AFFERENT and leaves through EFFERENT arterioles)


What is renal plasma flow?

When WHOLE BLOOD enters glomerulus but ONLY PLASMA is filtered by glomerular capillaries. Red blood cells are NOT filtered normally so RPF = RBF*(1-HCT)


What is normal renal plasma flow?

RPF = 1L/min*(1-.4) = 600ml/min


What are the major renal processes?



What is filtration?

process by which water and solutes leave vascular system (blood vessels) through filtration barrier and go into Bowman's Space


What is secretion?

process of moving substances from cytosol of epithelial cells that form walls of nephron into tubular lumen


What is reabsorption?

process of moving substances across epithelial layer into surrounding interstitium (*most of the time, this happens in 2 steps: substanes that are reabsorbed move from interstitium into surrounding blood vessels


What is excretion?

when substances exit the body (i.e. is present in final urine produced by body)


What is synthesis?

substance in construction from molecular precursors


What is catabolism?

substance is broken down into smaller component molecules


What percent of blood entering the kidney flows directly into the medulla without passing through the cortex?

0%! All blood must flow through the cortex before entering the medulla!


Substance T is present in urine. Does this prove that it entered the renal tubule by filtration at the glomerulus?

NO! It could have EITHER been FILTERED to go into the urine OR could have been SECRETED into urine


Substance J is NOT normally found in urine. Does this prove that it is neither filtered nor secreted?

NO! Substance J may have been filtered but 100% of it could have been reabsorbed back into blood stream. So, it could have been filtered but not appear in urine.


A substance is filtered in Bowman's space and excreted in the urine. How many cell membranes must it cross to exit the body?

0! Substances DON'T cross any cell membranes in the glomerulus. Instead, they need to pass through TIGHT defined spaces but not across any cell membranes.


A substance is FREELY filtered. Does this mean that it is all filtered?

No! FREELY FILTERED means that there's no barrier to its ability to be filtered. So, any substance that's freely filtered will show up in the TUBULE at the SAME CONCENTRATION as it appears in the PLASMA.


Where would you find macula densa cells -in the cortex or medulla?