Urinary Session 1- Introduction And Imaging Flashcards
Describe the main functions of the kidney
Regulation- Control concentration of key substances in ECF
Excretion- Excretes waste products
Endocrine- Synthesis of renin, erythropoietin, prostaglandins
Metabolism- Active form of vitamin D, catabolism of insulin, PTH, calcitonin
Define osmolality
Number of osmolality of solute per kg of solvent
Define osmolarity
Number of osmolarity of solute per litre of solvent
In normal conditions what is the osmolality of plasma?
280-310 mOsm/kg or 280-310 mmol/L
Same as interstitial/intracellular fluid
What ions is osmolality mainly determined by?
In ECF- Na+ and Cl- (80%)
In ICF- K+ (50%)
If osmolarity is higher in ECF which way will the water move?
Out of the cell (water moves from low to high osmolarity)
What are the differences in electrolyte composition of ICF and ECF?
ICF- high K+, low Na+, many large organic anions
ECF- low K+, high Na+, main anions Cl- and HCO3-
How are electrolyte differences between ECF and ICF maintained?
Active transport via sodium pumps
What are the consequences if the kidneys fail to control ECF?
Failure to control volume = changes in BP, tissue fluid and cell function
Failure to control osmolarity = cells shrink or swell
What ion in plasma can affect the pH of ECF?
Bicarbonate
How much urine is produced on average per day?
1.5L out of 180L/day that is filtered!
What structure is described as the functional unit of the kidney and how many are there per kidney?
1.5 million nephrons per kidney
Name all the sections of the nephron in the order in which fluid passes through them
Glomerulus Proximal convoluted tubule Loop of Henle Distal convoluted tubule Collecting duct
If all tubes within the urinary system are lined with epithelium, which direction does reabsorption occur in?
From inside the tube back into the body
Which substances are 100% reabsorbed?
Bicarbonate
Glucose
Amino acids
Why are more H+ ions lost in urine than are filtered?
It is actively secreted in the distal convoluted tubule
What blood flow do the kidneys need?
4ml/g/min
What percentage of CO do the kidneys need at rest?
22%
What substances are filtered out of the blood by the glomerulus?
Water, electrolytes and small molecules
What is the glomerular filtration rate determined by and what is the rate?
Afferent and efferent arterioles
125ml/min or 180L/day
What is the main function of the proximal convoluted tubule?
Reabsorption
Which substances are reabsorbed in PCT and how much of each (%)?
60-70% sodium and water
80-90% potassium
90% bicarbonate
100% glucose and amino acids
Is the filtrate isotonic or hypotonic at PCT?
Isotonic
How do reabsorbed materials leave PCT?
Peritubular capillaries
