1. The Excretory System

2. Functions of the Urinary System
Filtration of the blood
Occurs in the glomerulus of the kidney nephron
Contributes to homeostasis by removing toxins or waste

3. Urinary System Renal artery Renal Vein Kidney Ureter Urinary Bladder
For sphincters, see next slide
Unit 1 - Objective 1

4. Functions of the Urinary System
Reabsorption of vital nutrients, ions and water
Occurs in most parts of the kidney nephron
Contributes to homeostasis by conserving important materials

5. Urinary System Female Sphincters Male Sphincters
Internal urethral sphincter
External Urethral Sphincter
Unit 1 - Objective 1

6. Functions of the Urinary System
Secretion of excess materials
Assists filtration in removing material from the blood
Contributes to homeostasis by preventing a build-up of certain materials in the body such as drugs, waste,etc.

7. Functions of the Urinary System
Activation of Vitamin D
Vitamin D made in the skin is converted to Vitamin D3 by the kidney
Active Vitamin D (D3) assists homeostasis by increasing calcium absorption from the digestive tract
Unit 1 - Objective 1

8. Functions of Kidney Structures
The Renal Artery
Transports oxygenated blood from the heart and aorta to the kidney for filtration

9. Functions of Kidney Structures
Renal Vein
Transports filtered and deoxygenated blood from the kidney to the posterior vena cava and then the heart

10. Functions of Kidney Structures
Nephron
The physiological unit of the kidney used for filtration of blood and reabsorption and secretion of materials
Unit 1 - Objective 1

11. Functions of Kidney Structures
Capsule
The outer membrane that encloses, supports and protects the kidney

12. Functions of Kidney Structures
Cortex
The outer layer of the kidney that contains most of the nephron; main site for filtration, reabsorption and secretion

13. Functions of Kidney Structures
Medulla
inner core of the kidney that contains the pyramids, columns, papillae, calyces, pelvis and parts of the nephron not located in the cortex; used for salt, water and urea absorption
Unit 1 - Objective 1

14. Functions of Kidney Structures
Ureter
Transports urine from the renal pelvis to the bladder
Unit 1 - Objective 1

15. Functions of Kidney Structures
Renal Pyramids
Triangular shaped units in the medulla that house the loops of Henle and collecting ducts of the nephron; site for the counter-current system that concentrates salt and conserves water and urea

16. Diagram of Kidney Nephron
Efferent arteriole
Afferent arteriole
Bowman’s capsule
Collecting duct
Proximal convoluted tubule
Glomerulus
Peritubular capillaries
Vasa recta
Decending limb of loop of Henle
Ascending limb of loop of Henle
Distal convoluted tubule

17. Functions of Nephron Structures
Glomerulus
The site for blood filtration
operates as a nonspecific filter; in that, it will remove both useful and non-useful material
the product of the glomerulus is called filtrate

18. Functions of Nephron Structures
Bowman’s Capsule
A sac that encloses Bowman’s Capsule and transfers filtrate from the glomerulus to the Proximal Convoluted Tubule (PCT)

19. Functions of Nephron Structures
The primary site for secretion (elimination) of drugs, waste and hydrogen ions
Saves water for the body
Unit 1 - Objective 1

20. Site of Filtration Glomerulus the Glomerulus is the site of filtration
the filtration mechanism is sieve-like and consists of fenestrated glomerular capillaries, podocytes and a basement membrane that allows free passage of water and solutes smaller than plasma proteins

21. The Juxtaglomerular Apparatus
Used in maintaining blood pressure

22. Disorders of the Urinary System
Renal Calculi (kidney stones)
caused by the crystallization of calcium, magnesium or uric acid salts that precipitate in the renal pelvis.
If the calculi become large and travel down the ureter, they can cause excruciating pain

23. Disorders of the Urinary System
Cystitis
typically caused by bacteria from the anal region, but, can also be caused by sexually transmitted diseases and various chemical agents
can lead to inflammation, fever, increased urgency and frequency of urination and pain

24. Disorders of the Urinary System
Glomerulonephritis ( Bright’s Disease)
caused by inflammation of the glomeruli due to an abnormal immune response (autoimmune, streptococcal antibody complexes).
Inflammation of the glomeruli leads to faulty filtration (passage of blood cells and proteins) and possible kidney failure.

25. Disorders of the Urinary System
Incontinence
caused by loss of the ability to control voluntary micturition (releasing urine from the bladder) due to age, emotional disorders pregnancy, damage to the nervous system, stress, excessive laughing and coughing
leads to wetting of clothing, discomfort and embarrassment
Unit 1 - Objective 1

26. Dialysis Therapy
Dialysis is a process that artificially removes metabolic wastes from the blood in order to compensate for kidney (renal) failure.
Kidney failure results in the rapid accumulation of nitrogen waste (urea, etc.) which leads to azotemia.
Uremia and ion disturbances can also occur. This condition can cause acidosis, labored breathing, convulsions, coma and death.

27. Dialysis Therapy
The most common form of dialysis is hemodialysis which uses a machine to transfer patient’s blood through a semipermeable tube that is permeable only to selected substances.

28. Dialysis Therapy Some key aspects of hemodialysis are:
- blood is typically transferred from an arm artery
- after dialysis, blood is typically returned to an arm vein
- to prevent clotting, blood is typically heparinized
- dialysis sessions occur about three times a week
- each dialysis session can last four to eight hours!
- long term dialysis can lead to thrombosis (fixed blood clots),
infection and death of tissue around a shunt (the blood access
site in the arm)

29. Source:
Modified from Robert F. Allen