The Urinary System HLTAP301A

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)

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

Urinary System

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

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

The urinary system Structures Two kidneys Two ureters Urinary bladder Urethra

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

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

The kidney

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

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 150 – 180 litres Amount actually excreted as urine approx 1 – 1.8 litres Most of volume of filtrate is reabsorbed

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

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

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.

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

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

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

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

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

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