Flashcards in Urinary System Deck (65):
What does the urinary system consist of?
2 kidneys, 2 ureters, urinary bladder, urethra
What are 3 functions of the kidneys?
- formation and secretion of urine, regulates total body water, electrolyte and acid base balance and enables secretion of waste products.
- production and secretion of erythropoietin, the hormone that stimulates formation of red blood cells.
- production and secretion of renin, an important enzyme in the control of blood pressure.
What are the functions of the ureters?
Propel urine from the kidneys into the bladder by peristaltic contraction of the smooth muscle layer.
Is the intrinsic property of the smooth muscle is NOT under what control?
autonomic nerve control
Where does peristalsis originate?
In a pacemaker in the minor calyces.
What is the function of the urinary bladder?
Reservoir for storing urine
What is the function of the urethra?
Passes urine from bladder to exterior
What happens during the formation of urine?
Kidneys form urine which passes through the ureters to the bladder, waste products of metabolism are excreted, electrolyte levels are controlled and PH levels are maintained by the excretion of hydrogen ions.
What are the 3 processes involved in the formation of urine? Where do they occur?
Filtration - glomerus and glomerular capsule
Selective reabsorption - proximal convoluted tubule
Secretion - convoluted tubule.
What happens during filtration?
Water and other molecules filter through, blood cells, plasma proteins and other large molecules are too big so stay in the capillaries.
Why does filtration take place?
Difference between pressure in glomerulus and glomerular capsule.
Efferent arteriole is narrower than the afferent arteriole. Pressure builds up in the glomerulus, opposed by the pressure of the blood.
What is the glomerular filtration rate?
Volume of filtrate formed by both kidneys each minute. (125ml/min in a healthy adult)
What are the walls in the proximal convoluted tubule lined with?
Micro villi to increase surface area for absorption.
What materials essential to the body are reabsorbed?
Water, electrolytes, glucose
What type of absorption occurs spp during the reabsorption?
Some passive some active
How much of the filtrate reaches the nephron?
What is reabsorbed in the loop?
Water, sodium, chloride
How much of the filtrate reaches the distal convoluted tubule?
What is the filtrate like entering the collecting ducts?
What do the collecting ducts do?
Reabsorb as much water as the body needs.
What constitutes of glomerular filtrate not normally appear in Rhine unless blood levels are excessive?
Glucose, amino acids.
Transport maximum/renal threshold is...
Maximum capacity for reabsorption of a substance
Which substances are reabsorbed by active transport?
Sodium, calcium, potassium, phosphate and chloride.
What regulates the absorption of sodium, calcium, potassium, phosphate and chloride?
Which hormone regulates calcium reabsorption?
The anti diuretic hormone does what?
Increases water reabsorption
Which hormone increases reabsorption of sodium?
What does atrialniuretic peptide (ANP) do?
Decreases reabsorption of sodium and water
What is secreted during tubular secretion?
Substances not required and foreign materials eg drugs- penicillin and aspirin. Excreted in urine
Why is the excretion of hydrogen ions important?
Maintains blood PH
Describe the composition of urine
Oxalates - 2%
Why would urine be amber?
Due to the presence of uroblin
What is the normal PH of urine
What in the hypothalamus detects osmotic pressure in blood?
Where is water reabsorption stimulated in the kidneys?
Distal convoluted tubules and collecting ducts.
Describe the renin - angiotensin - aldosterone system
Low blood volume or low BP - sympathetic nerve stimulation - renin - angiotensin - angiotensin 1 - ACE converts to angiotensin 2 - potent vasoconstrictor - BP increases.
Renin + raised blood potassium levels stimulate the adrenal gland to release aldosterone - water reabsorbed with sodium increasing blood volume and reducing renin secretion - negative feedback
What is the role of ANP when blood volume is increased?
Stretch receptors in atria release ANP, reduces reabsorption of sodium and water, meaning more sodium and water is excreted lowers BP - negative feedback, inhibits secretion of ADH
How is PH balanced?
Cells of proximal convoluted tubules secrete hydrogen ions.
What do hydrogen ions (H+) form with to make?
Bicarbonate (HCo-3) forming carbonic acid (H2CO3)
Ammonia (NH3) forming ammonium ions (NH+4)
Hydrogen phosphate (HPO23-) forming dihydrogen phosphate (H2PO-3)
What is carbonic acid converted to?
CO2 and H20
What do the kidney and liver do to vitamin D?
Covert vit D to active metabolites, important in regulation of blood levels of calcium and phosphorus
How much of the arterial output do the kidneys receive?
Where does blood enter the kidney?
Through he renal artery at the hilium
What enters the glomerular capsule and subdivides into a cluster of tiny arterial capillaries forming the glomerulus?
What is between the capillaries?
Connective tissue phagocytic mesangial cells, monocyte - macrophage system
Which arteriole has a larger diameter?
The afferent arteriole
What does the efferent arteriole divide into?
Where does venous blood drained from the kidney leave?
Through the renal vein which empties into the inferior venae cavae
What are the walls of the glomerulus and glomerular capsule?
Single layer of flattened epithelial cells - more permeable.
What is the epithelium of the nephron and collecting duct?
Simple squamous epithelium
Blood vessels of the kidney are supplied by what?
Both SNS and PNS
What is metabolic acidosis?
PH below 7.35, depression of CNS disorientation, coma
What is metabolic alkalosis?
PH above 7.45 - convulsions, respiratory spasms
What mechanism is urine expelled from the body by?
What happens when urine is expelled from the body?
Destructor muscle contracts, internal sphincter relaxes and external sphincter relaxes
What is acute renal failure
Sudden and severe reduction in glomerular filtration rate and kidney function.
What can cause acute renal failure?
Severe or prolonged shock
Damage of the kidney
Obstruction to the outflow of urine
What is chronic renal failure?
Irreversible damage to 75% of nephrons
What are the main causes of chronic renal failure?
Diabetes, glomerulonephritis and hypertension
What are the symptoms of chronic renal failure?
Nausea, vomiting, GI bleeding, anaemia and pruritus (itching)
What is polyuria?
Large volumes of dilute urine
What is nochuria?
Needing the toilet at night
Deficiency of erythropoietin can cause what?
What is a consequence or a cause of renal failure?