L1 Intro To Renal Func

Question 1

Functions of the kidneys

Answer 1

Reg of water and inorganic ion balance

Reg of body fluid osmolality and vol

Excretion of metabolic waste (urea, uric acid, creatinine)

Excretion of foreign chemicals (drugs, pesticide, food additives)

Secretion of hormones (renin, erythropoietin, 1,25-dihydroxycholecalcoferol)

Reg blood bicarbonate levels

Question 2

Inputs

Answer 2

Beverages
Food
Metabolic

Question 3

Outputs

Answer 3

Insensible - water loss associated w skin evaporation and respiratory tract

Sweat

Fecal

Urinary

Question 4

Types of balance

Answer 4

Sodium balance

Water balance

Potassium balance

Others

Question 5

Balance equation

Answer 5

Total In - Total Out = Balance

Question 6

Negative sodium and water balance examples

Answer 6

Diarrhea

Diuretic meds

Insufficient aldosterone (ie adrenal dysfunction) regs Na reabsorption in kidney to maintain blood volume

Question 7

Positive sodium and water balance

Answer 7

Excess exogenous steroids

Congestive heart failure

Salt-retaining disease (ie hyperaldosteronism)

Question 8

Kidney gross anatomy

Answer 8

Cortex - granular

Medulla - striated
Renal pyramid
Urine excreted from papillae into calyces

Pelvis
Calyces drain into renal pelvis

Ureter

Question 9

Nephron anatomy

Answer 9

Basic unit of kidney

About 1 million per kidney

Tubular structure

Vascular elements

Juxtaglomerular apparatus (JGA) 
   Include two cell types: arteriolar supply of glomerular capillary, wall of nephron

Question 10

Components of nephron

Answer 10

Renal corpuscle

Proximal tubule

Loop of Henle

Juxtaglomerular apparatus JGA

Distal convoluted tubule

Collecting duct

Question 11

Renal corpuscle

Answer 11

Glomerulus - tuft of specialized capillaries

Bowmans capsule

Question 12

Proximal tubule

Answer 12

Drains bowmans capsule

60-80% of filtered solute and water reabsorbed (isosmotic)

Doesn’t concentrate urine

Also does a lot of secretion

Question 13

Loop of henle

LOH

Answer 13

Descending and ascending loops

Generates osmotic gradients in medulla that allow kidney to concentrate the urine

Ascending - thick

Descending - thin

It itself doesn’t do the concentrating

Question 14

Juxtaglomerular apparatus

JGA

Answer 14

Where thick ascending limb passes between afferent and efferent arteriole

Question 15

Distal convoluted tubule

Answer 15

Early distal tubule continues process of diluting urine

Some reabsorption of ions

Fluid hyposmotic

Question 16

Collecting duct

Answer 16

Water permeability controlled by vasopressin (ADH) anti-diuretic hormone

Site where final concentration of urine is adjusted- urine may be iso, hypo, or hyperosmotic

Question 17

Cortical nephrons

Answer 17

Glomeruli in outer cortex

LOH short and do not extend into the inner medulla

Most common type of nephron

Question 18

Juxtamedullary nephrons

Answer 18

Glomeruli near corticomedullary border

LOH long and extend deep into the inner medulla

Question 19

Two types of nephrons

Answer 19

Cortical and juxtamedullary

Ability to produce concentrated urine is proportional to the number of juxtamedullary nephrons (May or May not be true)

All nephrons function in parallel

Collecting ducts shared by many nephrons

Question 20

Renal corpuscle

Answer 20

Bowmans capsule Encompasses capillary tuft

Blood goes in through afferent arteriole and out through efferent arteriole

Capillaries within bowmans capsule have podocytes with individual projections called pedicels

Question 21

Filtration barrier consists of three layers

Answer 21

Capillary endothelium

Glomerular basement membrane = basal lamina

Visceral epithelial cells = podocytes
Pedicels are extensions of podocytes
Slits btw podocytes constitute the path of filtrate flow into the bowmans capsule

Question 22

Juxtaglomerular apparatus composed of

Answer 22

Macula densa

Extraglomerular mesangial cells EGM

Granular cells AK juxtaglomerular cells

Question 23

JGA function

Answer 23

Helps control GFR

controls renin secretion (BP and volume)

Question 24

Mesangial cells

Answer 24

Between capillary loops

Contract in response to hormone angiotensin II - compress glomerular tuft into tighter ball, decreases flow

Angiotensin II can enhance or retard GFR

Question 25

Renal vasculature

Answer 25

Two capillary beds: glomerular and peritubular

Question 26

Peritubular

Answer 26

Cortical division

Vasa recta division
Follow LOH of juxtamedullary nephrons
Found in medulla

Question 27

Blood supply to nephrons

Answer 27

Cortical arteries give off afferent arterioles

One afferent arteriole per glomerulus

Fluid not filtered goes to efferent arteriole

Then to peritubular capillaries which supple blood to nephron

Two arterioles (afferent and efferent) and two capillary beds (glomerular and peritubular) in series

Question 28

Vasa recta

Answer 28

Specialized peritubular capillaries of juxtamedullary nephrons

Long, hairpin shaped capillaries that follow LOH

Supply nutrient to medullary tissue and important for recovery of water

Question 29

Renal nerves

Answer 29

Sympathetic only- release norepinephrine and dopamine

Alpha1 receptors on afferent and efferent arterioles but primarily afferent

Stimulation by SNS tends to reduce RBF and GFR but the simultaneous release of prostaglandins PGE2 and PGI2 oppose alpha1 mediated vasoconstrictions. Reductions in RBF and GFR are minimized

Granular cells (JGA) innervated by SNS, renin released upon stimulation of B1 receptors

Question 30

Components of renal function

Answer 30

Glomerular function
Production of protein free filtrate
GFR is 120-125 ml/min

Tubular reabsorption
From tubular lumen to peritubular capillary

Tubular secretion
From peritubular capillary to tubular lumen

Excretion
Substance appears in urine