The kidney is composed of an outer cortex and inner medulla, and contains over 1 million functional filtration units called nephrons. Each nephron contains a renal corpuscle for blood filtration and a renal tubule for reabsorption and secretion. Urine is formed in 3 steps - filtration of blood into nephron filtrate, reabsorption of useful substances back into blood, and secretion of waste products into filtrate. Hormones like antidiuretic hormone regulate water and electrolyte balance by controlling reabsorption in the kidney tubules.

1. Kidney Physiology (pg 4)

2. Macroscopic Structure of the Kidney
• Cortex: Outer region

3. Macroscopic Structure of the Kidney
• Cortex: Outer region
• Medulla: Inner region

4. Macroscopic Structure of the Kidney
• Cortex: Outer region
• Medulla: Inner region
• Renal pelvis: large cavity that collects the
urine as it is produced. Continuous with ureter

5. Nephrons
• Nephrons are the functional unit of the kidney

6. Nephrons
• Nephrons are the functional unit of the kidney
• Over 1 million nephrons per kidney

7. Nephron Structure
Nephrons have two parts:

8. Nephron Structure
Nephrons have two parts:
1. Renal corpuscle
a. Glomerulus: cluster of capillaries

9. Nephron Structure
Nephrons have two parts:
1. Renal corpuscle
a. Glomerulus: cluster of capillaries
b. Glomerular (Bowman’s) Capsule: cup that
surrounds the glomerulus and receives
blood filtrate from it

10. 2. Renal tubule
a. Proximal convoluted tubule: Highly coiled.
Located in cortex

11. 2. Renal tubule
a. Proximal convoluted tubule: Highly coiled.
Located in cortex
b. Loop of Henle: A hairpin loop that dips into
the medulla, makes a U-turn, and ascends
back to the cortex

12. 2. Renal tubule
a. Proximal convoluted tubule: Highly coiled.
Located in cortex
b. Loop of Henle: A hairpin loop that dips into
the medulla, makes a U-turn, and ascends
back to the cortex
c. Distal convoluted tubule: Coiled, in cortex

13. Urine Formation
• Nephrons form urine in 3 steps
1. Filtration: Water and small solutes enter the
nephron (blood cells and proteins do not
enter). Filtrate is similar to blood plasma.

14. Urine Formation
• Nephrons form urine in 3 steps
1. Filtration: Water and small solutes enter the
nephron (blood cells and proteins do not
enter). Filtrate is similar to blood plasma.
2. Reabsorption: Useful substances (water,
glucose, amino acids, needed ions) are
transported out of the filtrate and back into
the blood

15. Urine Formation
• Nephrons form urine in 3 steps
1. Filtration: Water and small solutes enter the
nephron (blood cells and proteins do not enter).
Filtrate is similar to blood plasma.
2. Reabsorption: Useful substances (water,
glucose, amino acids, needed ions) are
transported out of the filtrate and back into the
blood
3. Secretion: Harmful substances (H+, excess K+,
some drugs and poisons) are removed from the
blood and put into the filtrate

16. Output (pg 5)
• Color code nephron diagram

17. Hormonal Control
• Hormones regulate the reabsorption of water
and electrolytes by the kidneys

18. Hormonal Control
• Hormones regulate the reabsorption of water
and electrolytes by the kidneys
• If blood volume drops, the pituitary gland
releases antidiuretic hormone (ADH)

19. Hormonal Control
• Hormones regulate the reabsorption of water
and electrolytes by the kidneys
• If blood volume drops, the pituitary gland
releases antidiuretic hormone (ADH)
• ADH causes the kidney duct cells to reabsorb
more water and produce less urine

20. Hormonal Control
• Hormones regulate the reabsorption of water
and electrolytes by the kidneys
• If blood volume drops, the pituitary gland
releases antidiuretic hormone (ADH)
• ADH causes the kidney duct cells to reabsorb
more water and produce less urine
• Alcohol inhibits ADH production

21. Hormonal Control
• Hormones regulate the reabsorption of water
and electrolytes by the kidneys
• If blood volume drops, the pituitary gland
releases antidiuretic hormone (ADH)
• ADH causes the kidney duct cells to reabsorb
more water and produce less urine
• Alcohol inhibits ADH production
• Inability to produce ADH is called diabetes
insipidus (water diabetes). Affected individuals
produce up to 25 liters of very dilute urine per
day and are constantly thirsty