1. The Urinary System
HLTAP301A

2. The urinary system
One of four excretory systems that contribute to waste management in the body
Digestive system (faeces)
Respiratory system (CO2)
Skin (water and salts)
Urinary (urine)

3. The urinary system Functions
To filter and eliminate waste from the body
To regulate body fluids
Helps to maintain homeostasis
Maintains blood pressure, electrolyte balance and blood pH
Involved in production of RBC
Organs, tubes, muscles and nerves work together to create, store and carry urine

4. Urinary System

5. The urinary system How does it work?
Body takes nutrients from food and uses them to maintain all bodily functions including
Energy
Self repair
Waste products remain in blood and bowel
Works with lungs, skin, intestines to keep chemicals and H2O balanced

6. The urinary system Urea
Produced when foods containing proteins are broken down
Carried in blood stream to kidneys where it is removed from blood as waste product

7. The urinary system Structures Two kidneys Two ureters Urinary bladder
Urethra

8. The urinary system Kidneys Bean shaped organs
Situated behind peritoneum on posterior wall of abdominal cavity either side of vertebral column
Right kidney slightly lower than left
Receive oxygenated blood from aorta via left and right renal arteries
Returns de-oxygenated blood to inferior vena cava via renal veins

9. The urinary system Kidneys cont…..
Surrounded by three layers of tissue
Fibrous renal capsule
Adipose capsule
Renal fascia
Microscopic functional units are nephrons
Form urine by filtering blood and removing metabolic waste
Consists of a ball formed of small blood capillaries and a tube called renal tubule

10. The kidney

11. The urinary system Formation of urine
Occurs within nephrons and collecting tubules and ducts
Three phases
Filtration
Re-absorption
Secretion

12. The urinary system Filtration Occurs when blood enters glomerulus
Blood pressure forces H2O and dissolved components through walls of glomerulus into glomerular capsule
Amount of filtrate formed in one day is approx – 180 litres
Amount actually excreted as urine approx 1 – litres
Most of volume of filtrate is reabsorbed

13. The urinary system Reabsorbtion Approx 99% of filtrate reabsorbed
This consists of H2O, nutrients and ions
Some H2O, wastes and substances are excreted
Microscopic nephron

14. The urinary system Secretion Urine
Tubular secretion moves additional substances from blood into nephron
Release of hormone ADH by pituitary gland allows more H2O to be reabsorbed from nephron
Urine
Clear amber coloured fluid
Slightly acidic
96% H2O
Mineral salts
Urea
Uric acid
Creatinine

15. The urinary system Ureter Two thin tubes connecting kidneys to bladder
Approx 17 – 20cms long
Muscles in walls contract and relax to force urine downwards (peristalsis)
Small amounts or urine empty into bladder from ureters every 10 – 15 secs.

16. The urinary system Urinary bladder
Hollow balloon shaped muscular organ
Situated in pelvis
Attached by ligaments to other organs and pelvic bones
Stores urine until urge to urinate
Can hold up to 2 cups of urine comfortably for 2 – 5 hours
Sphincters help keep urine from leaking
When full, brain signals muscle to tighten, squeezing urine out
Brain also signals sphincter muscle to relax
Urine exits bladder through urethra

18. The urinary system The urethra Muscular tube
Passage for urine from bladder out of body
Passing urine called micturition
Female urethra 2.5 – 4cms long
Male urethra 15 – 20cms long and opens at tip of penis
Passage way for both urine and semen

19. The urinary system Two systems controlling kidney function
Nervous system
Controls blood pressure required for filtration
Endocrine system
Hormonal control
When body needs to conserve H2O, kidneys excrete less urine
Urine appears darker and is more concentrated

20. The urinary system Blood pressure If blood pressure falls
Blood pressure in renal artery falls
Kidneys secrete hormone renin
Renin causes blood vessels to constrict
Decrease H2O and electrolytes
Blood pressure is raised

21. The urinary system Problems Caused by aging, illness, injury
Aging muscles in urinary system loose strength
More urinary infections
Incontinence
Urinalysis is a test studying content of urine for abnormal substances
Benign prostatic hyperplasia is enlargement of prostrate gland interfering with urination
Kidney stones can be found anywhere in urinary system and cause severe pain
Urinary tract infections caused by bacteria
treated with antibiotics

24. The urinary system Points to remember
Urinary system filters waste and extra fluid from blood
Problems include
Kidney failure
UTI
Kidney stones
Prostate enlargement
Bladder control problems
Health professionals treating urinary problems include
GPs
Paediatricians
Urologists
Gynaecologists
Nephrologists