Renal Function and Electrolytes Flashcards
What are four general functions of the kidneys?
- removal of unwanted substances
- homeostasis
- electrolyte and acid/base balance (and water balance)
- hormonal regulation
what encloses each kidney
a fibrous capsule of connective tissue
what are the two regions of the kidney?
outer region: cortex
inner region: medulla
what is the function unit of the kidney? And what are the parts of this unit (in order of flow?)
the nephron
- glomerulus
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collection duct
What surrounds the glomerulus? What carries the blood in and out?
capillary tuft surrounded by the Bowman’s capsule
afferent arterioles carries the blood in
efferent arterioles carries the blood out
What factors affects the filtration of the glomerulus?
glomerular capillaries (between two arterioles) induce steep glomerular filtration
the semipermeable membrane
what is the function of the semipermeable membrane?
allows water, electrolytes, and small solutes (eg glucose, amino acids, low molecular weight proteins) to pass through the basement membrane and enter the proximal convoluted tubule
keeps large molecular weight molecules (bilirubin, lipids, and albumin) unfiltered
neg particles repelled due to basement membrane being negatively charged
1200 - 1500 mL of blood is received in the kidneys, and the glomerulus filters out 125 - 130 mL of protein-free, cell-free fluid called ______ ______
glomerular filtrate
what is the function of the proximal convoluted tubule?
returns the bulk of each valuable substance (in the glomerular filtrate) back into blood circulation
what are the reabsorbed substances (from the proximal convoluted tubule?)
75% of water, 100% glucose, Na+, Cl-, amino acids, vitamins, proteins, ect
What happens when the concentration of a filtered substance exceeds capacity? What is this called? What is this used for?
the substance is excreted into the urine (when it exceeds capacity). This is called the renal threshold.
Renal threshold assess tubular function and non-renal disease states
what is the loop of henle’s function?
it maintains osmolality that develops in the medulla by facilitating the reabsorption of water, sodium, and chloride
what are the two parts of the loop of henle? What is the downwards flow and upwards flow through these two limbs called, and what are the functions of the two parts?
Descending limb: permeable to water but not to Na+ and Cl-, so urine is more concentrated in this section
Ascending limb: sodium and chloride actively and passively reabsorbed (into the medullary interstitial fluid) while water is not passed, so and the urine becomes hyperosmotic (dilute)
Concurrent flow is the flow between the two limbs
what is the function of the distal convoluted tubule since most of the filtration steps have nearly been completed by the proximal tubule and loop of henle?
the DCT only has to make small adjustments to achieve electrolyte and acid-base balance homeostasis
what are the two hormones that control distal convoluted tubule function, and what do they each do?
Argenine vasopressin (also called ADH: antidiuretic hormone) stimulated when blood volume DECREASES, so it allows for water reabsorption in the DCT
Aldosterone: made by the adrenal cortex under renin influence and secreted when blood flow is low.
- Stimulates sodium reabsorption into the DCT
- Stimulates K+ and H+ ion secretion
the collecting duct is the final site for either _______ or ________ urine. ADH (AVP) and aldosterone act on this duct to control reabsorption of what two things? What additional two things are reabsorbed here?
concentrating or diluting
water and sodium
chloride and urea
what are nonprotein nitrate compounds? What are the three that the kidneys need to excrete?
they’re waste products made as a result of degradation/metabolism of nucleic acids, amino acids, and proteins
need to get rid of
- urea
- creatinine
- uric acid
Urea is the nonprotein nitrogen compound found in _______ concentration in the blood. How is it formed?
it’s found in highest concentration in the blood (in comparison to the rest of the NPN compounds)
it’s made in the liver from amino groups and free ammonia (which is toxic) during protein catabolism
how is creatinine formed?
Creatine kinase adds a phosphate to creatine to make phosphocreatine. Phosphocreatine then takes that phosphate and adds it to ADP to make ATP (energy for muscles). In doing this, phosphocreatine is turned into creatinine.
Uric acid is a waste product of _______ metabolism.
purine metabolism
- adenine and guanine