L1 Intro To Renal Function

Question 1

Functions of the Kidneys

Answer 1

Regulation of water and inorganic ion balance

Regulation of body fluid osmolality and volume

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

Excretion of foreign chemicals (ie drugs, pesticides, food additives)

Secretion of hormones (Renin, Erythropoietin, 1,25-dihydroxycholecalciferol)

Regulate blood bicarbonate levels

Question 2

Normal daily water input

Answer 2

Food and water = 1900 ml
Oxidative water = 400 ml

Total = 2300 ml

Question 3

Normal daily water output

Answer 3

Fecal = 150 ml
Sweat = 250 ml
Insensible = 800 ml

Total output = 1200 ml

Question 4

If total water input = 2300ml and total water output = 1200ml, what happens to the remaining 1100ml/day?

Answer 4

Urine flow

If urine output = 1100ml/day, then the subject is in steady state

If urine output > 1100ml/day, then the subject is in negative water balance

If urine output < 1100ml/day, then the subject is in positive water balance

Question 5

Examples of physiologic conditions leading to negative sodium and water balance

Answer 5

Diarrhea
Diuretic medications
Insufficient aldosterone (ie adrenal dysfunction)

Basically, more water/sodium lost than brought in to the body

Question 6

Examples of physiological conditions resulting in a positive sodium and water balance

Answer 6

Excess steroids (anabolic substances)
Congestive heart failure
Salt-retaining disease (ie hyperaldosteronism)

Question 7

Gross structures of the kidney

Answer 7

Cortex (granular in appearance)

Medulla (striated)

• Renal pyramids
• Urine excreted from papillae into calyces

Pelvis - calyces drain into the renal pelvis

Ureter

Question 8

Basic functional unit of the kidney:

Answer 8

The Nephron

Millions in each kidney

Consists of tubular component and a vascular component, as well as a combined component (JGA)

Question 9

Different components of the nephron

Answer 9

Renal corpuscle (incl glomerulus and Bowman’s capsule)

Proximal tubule

Loop of Henle

Juxtaglomerular apparatus (JGA)

Distal convoluted tubule

Collecting duct

Question 10

_______ drains the Bowman’s capsule, and site of 60-80% of filtered solute and water reabsorption (isosmotic)

Answer 10

Proximal Tubule

Question 11

________ generates osmotic gradients in the medulla that allow kidney to concentrate the urine

Answer 11

Loop of Henle

Includes descending and ascending loops

Question 12

Where the thick ascending limb passes between the afferent and efferent arteriole

Answer 12

Juxtaglomerular apparatus (JGA)

Question 13

Site where final concentration of urine is adjusted (to make urine iso-, hypo-, or hyperosmotic)

Answer 13

Collecting duct

Water permeability controlled by vasopressin

Question 14

Nephrons with glomeruli in outer cortex and short loop of Henle that does not extend into the inner medulla

Answer 14

Cortical nephrons

Question 15

Nephrons with glomeruli near the corticomedullary border and long loop of Henle extending deep into the inner medulla

Answer 15

Juxtamedullary nephrons

Question 16

Ability to produce concentrated urine is thought to be proportional to…

Answer 16

The number of juxtamedullary nephrons

Question 17

All nephrons function in ______.

Answer 17

Parallel

Collecting ducts shared by many nephrons

Question 18

The three layers of the filtration barrier within the renal corpuscle

Answer 18

Capillary endothelium

Glomerular basement membrane (=basal lamina)

Visceral epithelial cells (=podocytes)
Peddles are extensions of the podocytes
Slits between podocytes constitute the path of filtrate flow into Bowman’s capsule

Question 19

Components of the juxtaglomerular apparatus (JGA)

Answer 19

Macula dense (MD)
Extraglomerular mesangial cells (EGM)
Granular cells (G, aka juxtaglomerular cells)

Question 20

Function of the juxtaglomerular apparatus (JGA)

Answer 20

Helps control GFR

Controls renin secretion (which in turn controls blood pressure and volume)

Question 21

_________ Cells between capillary loops contract in response to hormone angiotensin II

Answer 21

Mesangial cells

Question 22

The two capillary beds that comprise the renal vasculature

Answer 22

Glomerular

Peritubular
• Corticol
• Vasa Recta (follow LOH of juxtamedullary nephrons in the medulla)

Question 23

Corticol arteries give off ____________

Answer 23

Afferent arterioles

One afferent arteriole per glomerulus

Question 24

Fluid not filtered goes to __________.

Answer 24

Efferent arteriole, then to peritubular capillaries

Question 25

The two arterioles (afferent and efferent) and two capillary beds (glomerular and peritubular) are in ________.

Answer 25

Series

Question 26

Specialized peritubular capillaries of juxtamedullary nephrons

Answer 26

Vasa Recta

Long, hairpin shaped capillaries that follow the LOH

Question 27

__________ supply nutrients to medullary tissue and are important for recovery of water

Answer 27

Vasa Recta

Question 28

Renal nerves are _________

Answer 28

Sympathetic (release norepinephrine and dopamine

Alpha-1 receptors present on afferent and efferent arterioles, but primarily afferent arterioles

NO parasympathetic innervation

Question 29

Stimulation by the SNS tends to ….

Answer 29

Reduce RBF and GFR, but the simulaneous release of prostaglandins PGE2 and PGI1 oppose the effect so reductions in RBF and GFR are minimized

Question 30

Granular cells are innervated by ______ and _______ is released upon stimulation of ______ receptors

Answer 30

SNS; renin; beta receptors

Question 31

Production of a protein-free filtrate is called

Answer 31

Glomerular filtration

GFR is usually 120-125 ml/min

Question 32

Other components of renal function besides glomerular filtration

Answer 32

Tubular reabsorption (from tubular lumen to PTC)
Tubular secretion (from PTD to tubular lumen)
Excretion (substance appears in urine)