Function & Structure of the Kidney Flashcards Preview

Physiology Renal ABS 2018 > Function & Structure of the Kidney > Flashcards

Flashcards in Function & Structure of the Kidney Deck (90):

What are the 7 main kidney functions?

1. H20 &electrolyte balance
2. Waste product excretion
3. Bioactive substanc excretion
4. Arterial BP regualtion
5. RBC production (erythroipoitin)
6. Vitamin D regulation
7. *Metabolism


What are metabolic waste products?

something you metabolize/ make in your own body and it gets removed once you no longer need it


What are bioactive substances?

referring to drugs and hormones


What 2 types of waste products do we have in the body?

1. Metabolic
2. bioactive


Where is erythropoietin made?

by the kidney


What does balance mean?

Input= Output (What enters the body, must exit the body)


What are the 5 main metabolic waste products that can be harmful at high concentrations?

1. Urea
2. Uric acid
3. Creatinine
4. Hemoglobin waste products
5. Hormone metabolites


Where do the breakdown of the 5 main metabolic waste products comes from ?

1. Urea- from breakdown of proteins
2. Uric acid- from breakdown of nucleic acids
3. Creatinine- from the breakdown of muscle creatinine
4. Hemoglobin waste products- from the break down of Hb
5. Hormones metabolites- from endocrine system


What two ways are bioactive substances excreted from the body?

1. Actively
2. Passively


What 2 main ways do the kidneys use to regulate BP?

1. Control of blood volume
2. Release of vasoactive substances (active regulation of smooth muscle in peripheral vasculature)


High or Low blood volume = ?

High BP/ Low BP, respectively


What does Vitamin D tell the gut/GI tract to do ?

Increase Calcium absorption


What is the role of Vitamin D?

Huge role in Calcium level regulation


Explain the multistep process of Vitamin D. First and Last step?

1. UV rays (sunlight) through the skin
2. Liver also has a role
Last. Kidney converts it to vitamin D. Without a functioning kidney-- there is no Vitamin D!


In Metabolism, CNS uses what form of fuel?

ONLY Glucose


What happens where there is a drop in glucose levels? What 2 organs play a role?

Gluconeogenesis (where AA--> glucose)
Mainly Liver, but kidney also has a role.


What is renal ammonioagenesis? Why is this important?

1. Process by which the kidney makes ammonia (wast product) to release the acidity in the body
2. It maintains acid-base homeostasis


Where are the kidneys located?



What happens in the renal cortex?

1. ALL the filtration
2. A majority of reabsorption


What parts of the cortex extend in to parts of the medulla to separate it?

The renal columns (of the renal cortex)


Which part of the kidney contains more surface area?

The cortex - has more surface area than the medulla


What happens in the renal medulla?

1. Some reabsorption
2. Majority of collecting purposes
3. Final determinant of concentration or dilution of urine


What happens after the renal medulla?

Creation of finalized urine


What are the roles of the calyx, pelvis, etc of the kidney?

Drainage purposes


What is the functional unit of the kidney?

The nephron


What happens in the nephron?

1. Filtration
2. Reabsorption
3. determination of H20 & electrolyte balance


Where are the majority of the nephrons found?

Cortex- with a small portion found in the medulla


How many nephrons does each kidney have?

1 million


Where does filtration occur?



What gets filtered?

The plasma from the blood gets filtered through the glomerulus


Is there regulation of what enters the glomerulus?



How much fluid is filtered in the glomerulus per day?

180 L(plasma)/day


How much fluid is actually excreted/Urine output?

2L (urine)/ day


How much fluid is reabsorbed/ day?

Almost all of it


What makes up the renal corpuscle?

1. Glomerulus (capillary)
2. Bowman's capsule (balloon-like hollow capsule around the capillary)


What does the Bowman's capsule do?

Picks up the plasma that is filtered out of the glomerulus


What is the function of the Renal corpuscle?

Filter the blood


What is the fluid called once it leaves the Renal corpuscle?



How much reabsorption occurs at the Proximal tubule?

60 %


What is the proximal tubule? Name the 2 segments.

First part of the nephron
1. Proximal convoluted tubule
2. Proximal straight tubule


What is significant about the Loop of Henle? Specifically where in the kidney?

Creates a concentration gradient. (MEDULA osmotic gradient)


Normal osmolarity of ISF

300 mOSm/L


What is the only area in the body without an osmolarity of 300?

Area surrounding the loop of Henle


What happens moving down the length of the Loop of Henle in the ISF (surrounding LoH) ?

It gets more and more concentrated- from 300- max 1200 mOSm/L


What are the 3 segments of the loop of Henle?

1. Descending thin limb
2.Ascending thin limb
3.Thick ascending limb


What is the Macula Densa?

Demarkes the area b/w the Loop of Henle & Distal Tubule


What happens at the Distal tubule?Why is it significant?

1. Reabsorption of the rest of the stuff
2. Regulation occurs here- unlike in the proximal tubule


What occurs at the Collecting duct? Why is it significant?

1. A little Reabosprtion
2. H20 reabsorption


H20 reabsorption of the Collecting duct is regulated by which hormone? How does it work?

ADH- Anti-Dieuretic Hormone
1. ADH comes to the collecting duct and opens aquaporin channels (or inserts them on the membrane) to allow H20 to be reabsorbed back into the ISF/ leave collecting duct.


When does H20 leave the collecting duct?

When there is a concentration gradient. There must be a higher concentration gradient (of solutes)/ HIGHER OSMOLARITY outside the collecting duct- allows H20 to go to a place of higher concentration. NEED OSMOTIC PRESSURE


What happens in the case there is not a concentration gradient and ADH opens aquaporin channels? How concentrated will our urine get?

NO H20 would leave. the most concentrated our urine could be is 300 mOsm/L.


What are 2 important elements for H20 to leave the collecting duct?

1. ADH
2. Loop of Henle Concetration gradient established


Where in the nephron don't you have homogeneity of cell types?

Distal Tubule


What are the 2 cell types of the distal tubule? What are each of their roles?

1. Principal Cells- for reabsorption (primary role)
2. Intercalated Cells - for acid-base balance (2 kinds- alpha and beta cells) (HCO3- and K+ reabsportion; H+ secretion into tubular lumen)


What part of the nephron tubule actually touches the glomerulus? What is its significance?

the distal tubule (@ MACULA DENSA)
regulation of flow rate


What 2 major things occurs in the Renal Cortex? By which parts of the nephron?

Filtration- by the glomerulus
Majority of Reabsorption- by the proximal and distal tubule


What 2 major things occur in the Renal Medulla? By which parts of the nephron?

1.Concentration gradient- established by the loop of Henle
2.H20 Reaborsptlon- by the collecting duct- uses the concentration gradient to do this with ADH


What is the juxtaglomerular apparatus?

"next to the glomerulus"
Distal tubule (D.T) comes next to the glomerulus.
D.T -contains macula densa cells


What are macula densa cells?

Sensing cells of the D.T that sense flow rate


Explain the mechanism of macula densa cells.

LOW flow rate? -- will be sensed by the macula densa cells of the D.T. --> tell the juxtaglomerular cells this--> juxtaglomerular cells respond by RELEASING RENIN into the blood stream--> causes an INCREASE in flow rate (Increase amount of filtrate happening)


Where does Renin come from?

A substance released by the juxtaglomerular cells of the glomerulus to increase flow rate/ rate of filtration


5 actions of Angiotensin II in kidney? Where?

1. Increase Aldosterone release at D.T
2. Increases ADH release
3. Increases Vasoconstriction
4. Increase SNS activity
5. Tubular reabsorption of Na and CL; K excretion; H20 retention


What does each of these do?
1. Aldosterone (2 things)
2. ADH

a.Reabsorption of Na
b.Reabsorption of H20

2. opens aquaporin channels at collecting duct(to increase H20 reabosption)


What are the effects of vasoconstriction by Angiotensin II? what does it do to the glomerulus?

Increases total peripheral resistance (TPR) --> Increases blood pressure--> which in turn increases filtration amount at glomerulus


What determines the difference in nephrons?

The length of the loop of Henle


Name the 2 types of nephrons? 2 names? 3 names?

1. (outer) Cortical/ superficial nephrons- loop of Henle only extends until the cortex
2. Medullary/ Juxtamedullary/ Deep nephrons- loop of Henle extends into the medulla


What percent of our nephrons are cortical? juxtamedullary?

1. 80 % - cortical
2. 20 %- juxtamedullary


What percent of Cardiac Output (5 L/min) comes to the kidney?how many L?

20 % = about 1 L/min


How arteries go the kidney?branching?

1. Renal Artery
2. 1 million times to 1 million nephrons of the kidney (at each capillary)


What are the 7 branches of the renal artery?

Renal-->Segmental--> Interlobar--> Arcuate--> Interlobular--> Afferent Arteriole--> glomerulus--> Efferent Arteriole-->


What artery actually enters the glomerulus?

The afferent arteriole


Pathway of blood in Kidney.

Afferent--> Glomerulus (capuillary) --> Efferent Arteriole (should be a venule after a capillary)


Arteriole have what that venules don't?

Higher pressure due to smooth muscle


Arterioles of the kidney have what 2 advantages?

1. Higher pressure
2. Regulatory control


How many capillary systems does the kidney have? What are they? where?

1. Glomerulus (capillary)
2. For cortical nephrons: Peritubular capillaries (picks up everything that has been reabsorbed)
3. For juxtamedullary nephrons: vasa recta (surrounds loop of Henle)


Pathway of blood from Renal artery--> Renal Vein (13 steps)

1. Renal Artery
2. Segmental a.
3. Interlobar a.
4. Arcuate a.
5. Interlobular a.
6. Afferent Arteriole
7. Glomerulus
8. Efferent Arteriole
9. Peritubular capillaries (cortical) OR Vasa Recta (juxtamedullary)
10. Interlobular v.
11. Arcuate v.
12. Interlobar v.
12. Renal Vein


Pathway of blood from Renal artery--> Renal Vein (13 steps)

1. Renal Artery
2. Segmental a.
3. Interlobar a.
4. Arcuate a.
5. Interlobular a.
6. Afferent Arteriole (regulaltion site)
7. Glomerulus
8. Efferent Arteriole (regulation site/ NOT a venule)
9. Peritubular capillaries (cortical) OR Vasa Recta (juxtamedullary)
10. Interlobular v.
11. Arcuate v.
12. Interlobar v.
12. Renal Vein


What's the difference between plasma and blood?

NO RBCs in plasma!!


Renal Blood Flow. Normal value?

a. 1 L/ min of blood is filtered by the glomerulus
b. what enters the afferent arteriole and exits the efferent arteriole


Renal Plasma Flow. Normal value?

a. Renal Plasma Flow = Plasma Blood Flow/ (1 - Hct)
b. 600 mL/ min (if Hct = .4)---

RPF= RBF/ 1-Hct==>
600 mL/min= 1L/min/( 1-.4)


What is the normal filtration rate?

125 mL/min


What are the 3 processes that determine eventual urine output?

1. Glomerular Filtration
2. Tubular Reabsorption
3.Tubular Secretion


Excretion= ?

Excretion= Filtration - Reabsorption + Secretion (E=F-R+S)


What is secretion? Why it occurs?

1. Moves substances from the blood into the nephron to later be excreted.
2. The need to get rid of stuff that isn't filtered enough in the urine


Define Filtration.

The process by which H20 and solutes leave the vascular system through the filtration barrier and enter Bowman's space


Define Secretion.

The process of moving substances into the tubular lumen from the cytosol of epitihelial cells that form the walls of the nephron


Define Reabsorption. What happens in most cases?

the process of moving substances from the lumen across the epithelial layer into the surrounding interstitium
*IN most cases- reabsorbed substances then move from the interstitium into surrounding blood vessels (2 step process)


Define Excretion.

Exit of the substance from the body (substance is present in the final urine produced by the kidney)


Define Synthesis.

Substance in construction from molecular precursors


Define Catabolism.

The substance is broken down into smaller component molecules