Renal Flashcards
Reabsorption describes fluid moving from the _____ to ____
Lumen (of nephron) to epithelial cell (and ultimately into capillary)
Filtration describes the movement of fluid from _____ to ____
Glomerulus to the proximal convoluted tubule
The side of the epithelial cell that is closest to the lumen is called the ____membrane
Apical
The side of the epithelial cell that is closes to the capillary is called the ____membrane
Basolateral
____is the 2nd leading cause of renal failure
High blood pressure
The 5 functions of the kidneys are
- Remove waste/ toxins from blood
- Maintain water and electrolyte balance
(Excrete water and lytes or secrete renin) - Maintain pH of blood (excrete H+ and create HCO3-)
- Secrete EPO
- Activate vitamin D
Kidneys are responsible for 1. ridding the body of _____ soluble wastes and 2. Maintain homeostasis of _____ and _____
Water soluble. Homeostasis of fluid and electrolytes
Two endocrine functions of the kidney are:
- producing EPO
2. Activating vit D (cofactor for intestinal calcium absorption)
T/F: nephrons are regenerated when damaged.
False- one million in each kidney. Have these for life. Thats why older people tend to have more issues with renal disease
Serious renal impairment occurs when what percentage of nephrons are damaged?
75-90%. Clinical findings are usually late in the progression of disease
Secretion can be described as fluid or molecules moving from ____ to ___ and finally _____
Blood to epithelial cell and out to lumen
The structures of the urinary system includes
Kidneys
Ureters
Urinary bladder
Urethra
Nephrons lie in what structure of the kidney?
Pyramids
Nephrons drain into what structure of he kidney
Renal calyx
Describe the arterial supply of the kidney
Renal artery -> interlobar arteries -> arcuate artery -> interLOBULAR artery-> afferent arterioles
What percentage of CO is circulated to the kidneys?
25%
Efferent arterioles form peri tubular capillaries aka ____ that wrap around the nephron structures
Vasa recta
Filtration occurs mainly in the ___
Glomerulus
What prevents large cells and negatively charged molecules from passing into the proximal convoluted tubule?
Basement membrane and slit pores of podocytes
Injury to the glomerulus may result in what in the urine?
Blood and proteins
Proteinurea represents wha type of dysfunction
Basement membrane
Only (small/large) molecules and (+/-) charged molecules can pass through the glomerulus
Small and +
The glomerulus has 3 types of cells. They are:
- Endothelium
- Podocytes
- Mesangial cells
Four functions of mesangial cells:
- Provide structural support for glomerular capillaries
- secretes matrix of proteins
- phagocytosis
- regulates GFR
The majority of the absorption proteins, amino acids, bicarbonate, and glucose occur in the ____
Proximal tubule
What 2 molecules are the result of protein breakdown?
Creatinine -muscle breakdown
Urea- amino acid breakdown
These should be in urine only- if in blood there is some type of renal issue.
_____is a good marker of renal function because it is freely filtered, not reabsorbed and negligibly secreted.
Creatinine
____is responsible for concentrating urine in the ____ of the nephron
Urea. Reabsorbed in the collecting tubule in the medullary nephron
Describe the process of glucose reabsorption
Glucose is filtered freely. Under NORMAL conditions, all glucose is reabsorbed by SGLT2 in the proximal tubule. GLUT 2 then transport it into the capillary.
Glycosuria results from what?
SGLT2 transporters on the apical membrane are overwhelmed by excess tubular loads of glucose. The renal threshold is reached earlier, so glucose appears in urine.
How do the kidneys regulate acid-base balance?
Kidneys excrete excess H+ and regulate the concentration of bicarbonate (HCO3-)
HCO3- is filtered freely but needs to be effectively reabsorbed to maintain acid-base balance.
What is the one equation we should all know?
CO2+ H2O H2CO3 HCO3- + H+
What are the two buffers of urine that bind to H+ so that the kidneys can excrete an acid load?
HPO4(2-) and NH3: phosphate and ammonia
How do the kidneys compensate for abnormal lung function in terms of acidosis (high PaCO2)?
Excrete more H+ by creating new HCO3- formed by glutamine metabolism.
How do the kidneys compensate for abnormal lung function in terms of alkalosis (low PaCO2)?
Kidneys will excrete some of filtered load of HCO3-
Potassium excretion is promoted by the Na/K pump on the _____ membrane
Basolateral
_____regulates (increases) potassium excretion in what part of the nephron?
Aldosterone. In the distal tubule
Besides aldosterone, what are 2 other regulators of K+ excretion?
K+/H+ exchanger and the plasma concentration of K+
Fluid homeostasis is maintained by what factors in the collecting tubule?
ADH activates cAMP which activates aquaporins on the apical membrane in the collecting tubule and water is then reabsorbed.
Insufficiency of ADH can lead to
Diabetes insipidus
- large volumes of dilute urine excreted
- severe fluid imbalance
The condition where the collecting tubules are unresponsive to ADH is called____
Nephrogenic diabetes insipidus
What 3 things cause renin to be released?
- Decreased renal blood flow
- Reduced serum Na
- Activations of sympathetic nerves to the JG cells (juxtaglomerular)
Renin release causes:
Angiotensin I to be converted to angiotensin II by ACE.
What causes natriuretic peptides to be released?
- Atrial cells I. Heart overstretched by increased blood volume
Natriuretic peptide release will (stimulate/inhibit) the actions of ______
Inhibit angiotensin II
Natriuretic peptide release does what to sodium and water?
Excreted in urine.
Urodilatin is released when the ______ and ______ sense an increased circulating blood volume
Distal convoluted tubule and collecting tubule
Urodilatin does what to sodium and water?
Inhibits reabsorption aka excretes it in urine (similar to natriuretic peptides)
How do diuretic agents work?
They oppose the reabsorption of water by altering the osmolality of urinary filtrate, leads to increased urine volume
Osmotic diuretics work by (increasing/decreasing) the osmolality of filtrate causing water to remain in the tubule.
Increasing
Which drugs inhibit the conversion of angiotensin I to angiotensin II and aldosterone?
ACE inhibitors
___ diuretics block the Na/K/2Cl pumps in the ____ loop of henle
Loop diuretics. Ascending loop (thick ascending loop)
Which diuretic blocks Na reabsorption?
Thiazide-like diuretics
K+ wasting diuretics are:
Loop, osmotic, thiazide-like
Which type of diuretics are K+ sparing?
Aldosterone blocking agents
Renal function is impaired at both ends of the lifespan, describe them.
Infant - early postnatal period, GFR low, immature kidneys can’t make concentrated urine (volume depletion with fluid losses)
elderly- kidneys diminish in size and function after 40, significant decrease by 65.
Geriatric considerations of kidney function (5)
- loss of nephron
- diminished renal blood flow
- decrease in GFR
- decreased ability to conserve Na, water
- susceptible to fluid/electrolyte imbalance, renal damage
What 4 urine and blood studies are helpful in evaluating kidney function?
- UA
- Serum creatinine (if in blood, there is renal impairment, should be cleared in urine)
- BUN levels
- tests of GFR
what is the synthetic (exogenous form) molecule used to measure renal function?
inulin (like creatinine, is freely filtered, not reabsorbed)