The Urinary System Flashcards
1
Q
What does the urinary system consist of ?
A
- (The organs of the urinary system include kidneys, urethras, urinary bladder and urether)
- The kidneys filter blood and return most of the water and solutes to the blood, the remaining water and solutes form urine
- Regulate blood composition, electrolytes balance, blood volume, blood pressure, blood ph
- Release calcitriol and erythropoietin and excrete wastes and foreign substances
2
Q
Functions of the urinary system
A
- (Regulate blood volume and composition, regulate blood pressure and ph, produce two hormones and excrete wastes)
- Transports urine from the kidneys to the urinary bladder
- The urinary bladder stores urine and expels it into the urethra
- The urethra discharges urine from the body
3
Q
Structure
A
- Lie on either side of the vertebral column between the peritoneum and the back wall of the abdominal cavity – 10-12 cm
- Each kidney is enclosed in a renal capsule which is surrounded by adipose tissue
- Internally the kidneys consist of a renal cortex, renal medulla, renal pyramids, renal columns, major and minor calyces and a renal pelvis
- Blood enters the the kidney through the renal artery and leaves through the renal vein
- The nephron is the functional unit of the kidney. consist of glomerulus and glomerular bowman’s capsule and a proximal convoluted tubule and distal convoluted tubule . each nephron has a blood supply. the distal convoluted tubules empty into common collecting ducts
4
Q
Functions of nephrons
A
- Non selective glomerular filtration, selective tubular reabsorption, tubular secretion
- The podocytes and glomerular endothelium form a leaky filtration membrane that permits the passage of water and solutes from the blood into the capsular space. blood cells and most plasma proteins remain in the blood because they are too large to pass through the filtration membrane. the pressure that causes filtration is the blood pressure in the glomerular capillaries
- The amount of filtrate that forms in both kidneys every minute is the glomerular filtration rate
- Most water is reabsorbed by osmosis together with reabsorbed solutes mainly in the proximal convoluted tubule
- Tubular reabsorption retains substances needed by the body including water, glucose, amino acids and ions
- Tubular secretion discharges chemicals not needed by the body into the urine, included are excess ions, nitrogenous wastes, hormones and certain drugs. the kidneys help maintain blood ph by secreting H+. tubular secretion also helps maintain proper levels of K+ in the blood
- (Filtration – in the glomerular blood plasma and dissolved substances get filtered into the glomerular capsule)
- (Reabsorption – all along the renal tubule and collecting duct, water ions and other substances get reabsorbed from the renal tubule lumen into the peritubular capillaries and ultimately into the blood)
- (Secretion – All lining the renal tubule and collecting duct, substances such as wastes drugs and excess ions get secreted from the peritubular capillaries into the renal tubule, these substances make there way into the urine)
5
Q
Glomerular filtration
A
- The glomerulus has a semi-permeable basement membrane that offers minimal resistance to fluid but prevents loss of larger cells and proteins
- Blood cells and most plasma proteins remain in the blood because they are too large to pass through
- Filters 100-120mls/min
- 180 litres/day
- 99% is reabsorbed in the renal tubules and collecting ducts leaving a urine output of 1-2 litres/day
6
Q
Negative feedback of water reabsorption of ADH
A
- Negative feedback blood water concentration down = dehydrated
- (ADH released by hypothalamus which increases reabsorption of water and sodium from the duct back into the blood stream and blood more dilute which increases in blood water concentration = rehydrated or in excess fluid overloaded sits outside the cells causes oedema)
7
Q
Composition of normal urine
A
- Water 96%
- Urea 2%
- Uric acid, ammonia, creatinine, sodium, potassium, chlorides, phosphates, sulphites 2%
8
Q
Physical characteristics of normal urine
A
- Volume – one to two litres in 24 hours
- Yellow or amber. colour is due to urochrome and urobilin. concentrated urine is darker in colour. diet affects colour. kidney stones may produce blood in urine
- Turbidity – transparent when freshly voided but become turbid after a while
- Odour – mildly aromatic but becomes ammonia
- Ph – ranges between 4.6-8 average is 6
- Specific gravity – specific gravity is the ratio of the weight of a volume of a substance to the weight go an equal volume of distilled water. ranges from 1.001 to 1.035
9
Q
Transportation, storage, elimination of urine
A
- The ureters transport urine via peristalsis from the renal pelvis of the right and left kidneys to the urinary bladder and consists of a mucosa, muscularis and adventitia
- The urinary bluffer is posterior to the public symphysis. its function is to store urine prior to micturition. the mucosa of the urinary bladder contains stretchy transitional epithelium. the muscular layer of the wall consists of three layers of smooth muscle together referred to as detrusor muscle
- The urethra – the canal from the back of the neck of the bladder to the exterior
- Function is to is charge urine from the body
- The micturition reflex discharges urine from the urinary bladder by means of parasympathetic impulses that cause contraction of the detrusor muscle and relaxation of the internal urethral sphincter muscle and by inhibition of somatic motor neurons to the external urethral sphincter
10
Q
Functions of the kidney
A
- Excrete urine – removal of metabolic waste products such as urea and creatinine toxins and water soluble drugs
- Regulation of body water volume
- Regulation of electrolyte balance
- Production of erythropoietin
- Control of blood pressure via water and salt regulation and renin production
- Regulation of acid base balance PH by re absorbing bicarbonate and excreting hydrogen ions
- Activates vitamin D
- When the body needs energy, fats and proteins synthesised via the kidney to produce new glucose as energy and release into the blood
11
Q
Ureters
A
- Transports urine from the kidneys to the urinary bladder
- The ureters tunnel a short distance within the urinary bladder wall
- As the urinary bladder fills it expands and compresses the ureters thereby preventing the back flow of urine
12
Q
Rugae
A
In the mucosa of the urinary bladder and the lining transitional epithelium allow the urinary bladder to expand as it fills
13
Q
Peritoneum
A
Helps hold the urinary bladder in place
14
Q
Internal urethral sphincter
A
Smooth muscle that opens and closes the urethra involuntarily
15
Q
External urethral sphincter
A
Skeletal muscle that opens and closes voluntarily
