Npb_Renal Physiology

Front 1

Function of the
Urinary System

Back 1

regulate volume, electrolyte composition, pH of the internal environment

Front 2

Components of the
Urinary System

Back 2

- pair of kidneys: forms urine
- pair of ureters: carries urine to the urinary bladder
- urinary bladder: stores urine
- urethra: empties the bladder of urine

Front 3

Function of the
Kidney

Back 3

- Maintaining H2O balance in the body

- Regulating the quantity and concentration of most extracellular (ECF) fluid ions

- Maintaining proper plasma volume

- Helping maintain proper acid-base balance of the body

- Maintaining the proper osmolarity of body fluids

- Excreting the end products of bodily metabolism such as urea and uric acid

- Excreting foreign compounds such as drugs, food additives, pesticides

- Secreting erythropoietin, a hormone that stimulates red blood cell production

- Secreting renin, a hormone important in salt conservation by the kidneys

- Converting vitamin D into its active form

Front 4

Blood enters the kidney via:

Blood leaves the kidney via:

Back 4

- rernal artery

- renal vein

Front 5

Define nephron.

Back 5

def. functional unit of the kidney
- consists of 3 components:
+ vascular component
+ tubular component
+ combined vascular/
tubular component

Front 6

3 components of a nephron

Back 6

- vascular component
- tubular component
- combined vascular/tubular component

Front 7

Parts of the Vascular Component

Back 7

- Afferent arteriole : brings blood to the glomerulus

- Glomerulus : tuft of capillaries that filters plasma into the tubular component

- Efferent arteriole : carries blood from the glomerulus; only arteriole in body post capillary

- Peritubular capillaries : supply the renal tissue; involved with exchanges with tubular lumen

Front 8

Parts of the Tubular Component

Back 8

- Bowman’s capsule - collects the glomerular filtrate

- Proximal tubule - uncontrolled reabsorption and secretion of selected substance

- Loop of Henle - establishes osmotic gradient that is important for concentrating urine

- Distal tubule and collecting duct - variable control of Na+ and H2O reabsorption and K+ and H+ secretion

Front 9

Parts that are Combined Tubular and Vascular Components

Back 9

Juxtaglomerular apparatus:
- region where the glomerulus and the ascending limb of the Loop of Henle are close to each other
- also region where ascending limb passes through the fork formed between the affereent and efferent arteriole
- secretes substances involved in the control of kidney function.

Front 10

2 layers composing the kidney

Back 10

- renal cortex : outer, granular layer
- renal medulla: inner, striated appearing

Front 11

2 types of nephrons

Back 11

1) cortical nephron
- 80%
- glomeruli located in outer layer of the cortex
2) juxtamedullary nephron
- 20%
- Glomeruli located in inner layer of renal cortex
- Loop of Henle present

Front 12

3 Processes in the
Formation of Urine

Back 12

1. Glomerular filtration – nondiscriminant filtration (except for red blood cells) of a protein-free plasma from the glomerulus into the Bowman’s capsule
2. Tubular reabsorption - selective movement of filtered substances from the tubular lumen into the peritubular capillaries
3. Tubular secrtetion - selective movement of nonfiltered substances from the peritubular capillaries into the tubular lumen

Front 13

Of the 180 liters of plasma filtered per day, how much is reabsorbed?

Back 13

178.5 liter

Front 14

3 Layers of the
Glomerular membrane

Back 14

1. Wall of the glomerular capillaries
- consists of large pores called genestrae
- >100 x permeable to H20 & solute than other capillaries

2. basement membrane : acellular gelatinous layer
- consists of collagen to provide structural support & glycoproteins which is negatively charged, repelling proteins(ex. albumin)

3. inner layer of Bowman's capsule
- consist of podocytes that intertwine w/foot processes to form filtration slits

Front 15

3 physical forces involved in glomerular filtration

Back 15

(1) glomerular capillary blood pressure : the fluid pressure exerted by blood within the glomerular capillaries (favors filtration)
*most susceptible to changes for GFR

(2) plasma-colloid osmotic pressure
- caused by unequal distribution of plasma proteins across the plasma membrane. H2O wants to move down osmotic gradient from Bowman’s capsule into glomerulus (opposes filtration)

(3) Bowman’s capsule hydrostatic pressure
- the fluid pressure exerted by filtrate in the Bowman’s capsule (opposes filtration)

Front 16

Factors affecting Glomerular filtration Rate (GFR)

Back 16

1) the net filtration pressure
2) the amount of glomerular surface area available for penetration
3) the permeability of the glomerular membrane

Front 17

2 Mechanism of GFR regulation

Back 17

1) Sympathetic Control - involves baroreceptor reflex

2) Autoregulation

Front 18

In glomerular filtration, what percentage of plasma is filtered and where are the destination of each type of plasma (filtered or unfiltered)?

Back 18

1) 20% filtered; excreted as urine
2) 80% unfiltered; exit via efferent arteriole to the venous system