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What is the difference between afferent and efferent arterioles?
Afferent carry blood toward the nephron, efferent carry blood away
Where are the kidneys located?
Outside the peritoneal cavitiy in the back of the upper abdomen, level of t12-L3
How much blood flow do the kidneys receive?
About 22% of cardiac output
What are the high and low pressure systems for in the nephron?
- High for filtration
- Low for reabsorbtion
What happens if you increase resistance in the Afferent arterioles?
What happens when the Efferent arterioles constrict?
Hydrostatic pressure increases so gfr increases but renal blood flow decreases so filtration fraction decreases
Describe the proximal convoluted tubule
- Highly coiled
- Drains bowmans capsule
- Rich in mitochondria
- Regulates filtrate ph by exchanging H+ in interstitium for bicarb in filtrate
- Site of origination for renal cell carcinoma
What is symport?
Transportation of different molecules or ions in the SAME direction by a common carrier
What is antiport?
Transportation of different ions in OPPOSITE directions
What are the elimination functions of the kidney?
- Renal clearance
- Regulation of sodium
- Pottasium elimination
- pH dependent elimination of ions
- Uric acid
Describe the juxtaglomerular complex
- Juxtaglomerular cells are modified smooth muscle cells in afferent and sometes efferent that contain renin
- Extraglomerular mesangium (lacis cells) phagocytic located in angle between afferent and efferent
- Macula densa of DCT triggers renin release
- Granular epithial peripolar cells at angle of parietal to viseral capsule at corpuscle controls ecf and gfr thru renin-angiotensin
What is the definition of renal clearance?
The volume of plasma that is completely cleared each minute of any substance in the urine
What determines renal clearance?
- Ability of the substance to be filtered by glomeruli
- The capacity of the renal tubules to reabsorb or secrete the substance
What are the characteristics of normal urine?
- Clear to amber color
- 95% water 5% dissolved solids
- Normally 1.5L a day
- Metabolic wastes and no proteins blood cells or glucose
What are some tests for renal function?
- Blood test - serum creatinine blood urea nitrogen
- Radiologic and other imaging
What happens during sympathetic stimulation of the kidneys?
Blood flow is directed to the medulla to maintain urine concentrating to maintain blood volume such as in shock
What are the two types of nephrons?
Cortical (85%) and juxtamedullary (15%)
The thin double walled capsule that surrounds the capillaries in the glomerulus
Perforations in glomerular capillaries endothelial layer
Structures in the epithelial layer that contain slit pores?
Foot processes or podocytes
What are the four segments of the nephron tubule?
PCT, loop of henle, DCT, CT
What are Mesengial cells?
Support glomerulus cailleries where basment membrane and endothelium dont cover, secrete substance similar to basement membrane, may be involved in regulation of blood flow
What are the two segments of the DCT?
- The diluting sement
- Late distal tubule
What are the two segments of the collecting tubule?
- Cortical collecting tubule
- Inner medullary collecting tubule
What layers do the tubules consist of?
Single layer of epithelial cells resting on a basement membrane
What can happen during sting sympathetic stimulation such as shock?
Gfr and urine output can drop to zero
65% of all reabsorption and secretory processes occur where?
What are the endocrine functions of the kidney?
- Activation of vitamin D
How do loop diuretics like lasix work?
Reduce sodium and potassium reabsorbtion and increase calcium and magnesium elimination in the thick ascending loop of henle
How do thiazide diuretics work?
They prevent the reabsorbtion of sodium in the early DCT