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32 Cards in this Set

  • Front
  • Back
What is the hilus of the kidney?
- a deep fissure indentation at the medial border of the kidney - the location where blood vessels, nerves, and ureters enter the kidney
What are the 2 sections of the kidney?
outer cortex and inner medulla
Describe the branching the renal artery in the kidney
renal artery » 5 segmental arteries » lobular arteries » interlobular arteries » arcuate arteries » intralobular arteries » afferent arterioles
What are the 2 capillary systems that supply the nephron?
the glomerulus and the peritubular capillary network
What is the glomerulus?
- high-pressure capillar filtration system located between the afferent and the efferent arterioles - the glomerulus can selectively dilate or constrict to regulate glomerular capillary pressure
What are the 2 types of capillaries that supply the medullary nephrons?
1. peritubular capillaries 2. vasa recta
What is the function of the nephron?
at the nephron, water, electrolytes, and other substances needed to maintain homeostasis are reabsrobed into the blood stream while other uneeded materials are secreted in the tubular filtrate for elimination
What are the 4 segments of the nephron tubule?
1. proximal convoluted tubule - drains the Bowman's capsule 2. Loop of Henle 3. distal convoluted tubule 4. collecting tubule - joins with several tubules to collect the filtrate
Name and describe the 2 groups of nephrons
1. cortical nephrons - 85% of nephrons; originate in the superficial part of the cortex; have short and thick loops of Henle that penetrate only a short distance into the medulla 2. juxtamedullary nephrons - 15% of nephrons; originate deeper in the cortex; have longer, thinner loops of Henle that penetrate the entire length of the medulla; largely concerned with urine formation
How is the initial fluid that is filtered through the glomerular capillaries different from plasma?
- the glomerular filtrate has a chemical composition to plasma, but it contains almost no proteins because large molecules do not readily cross the flomerular wall
What is glomerular filtration rate (GFR)?
the rate of filtrate formed each minute
How is the filtration pressure and the GFR regulated?
by the constriction and relaxation of the afferent and efferent arterioles
What is the effect of constriction of the afferent arteriole?
a decrease in glomerular filtration, renal blood flow, and GFR
What is the effect of constriction of the efferent arteriole?
increases resistance to outflow from the glomeruli and increases the glomerular pressure and the GFR
What are the 2 membrane surfaces of the renal tubular cell through which substances must pass as they are reabsorbed from the tubular fluid?
1. luminal membrane - the side of the cell that is in contact with the tubular lumen and tubular filtrate 2. basolateral membrane - the outside membrane that lies adjacent to the interstitial fluid
What occurs at the proximal tubule?
- approximately 65% of all reabsorptive and secretory processes - almost complete reabsorption of nutritionally important substances (glucose, amino acids, lactate, water-soluble vitamins, and electrolytes)
What are the 3 segments of the loop of Henle?
1. thin descending segment 2. thin ascending segment 3. thick ascending segment
What happens to fluid as it moves down the thin descending limb?
water is reabsorbed until the osmolality of the tubular fluid reaches an equilibrium with the interstitial fluid
What happens to the fluid as it moves up the ascending limb?
the ascending limb is impermeable to water and solutes are reabsorbed
At what part of the nephrone does aldosterone exert its effects?
at the late distal tubule and the cortical collecting tubule
Where does ADH exert its effects?
at the medullary collecting duct
What are some characteristics of loop diuretics?
- exert their effect in the thick ascending loop of Henle - most effective diuretic agents available - reduce the reabsorption of NaCl, decrease potassium reabsorption, and increase calcium and magnesium elimination
What are some characteristics of thiazide diuretics?
- act by preventing the reabsorption of NaCl in the distal convoluted tubule - produces increased losses of potassium in the urine, uric acid retention, and some impairment of glucose tolerance
Name some substances that causes vasoconstriction of renal vessels
angiotensin II, ADH, and endothelins
Name some substance that produce vasodilation in renal vessels
dopamine, nitric oxide, and prostaglandins
Describe the effects of aldosterone on sodium reabsorption
- in the presence of aldosterone, almost all the sodium in the distal tubular fluid is reabsorbed - in the absence of aldosterone, virtually no sodium is reabsorbed from the distal tubule
What are some of the affects of atrial natriuretic peptide?
- vasodilation of the afferent and efferent arterioles, which results in an increase in renal blood flow and GFR - inhibits aldosterone secretion by the adrenal gland and sodium reabsorption - inhibits ASH release from the posterior pituitary gland, thereby increase water excretion by the kidney
Describe how the kidneys regulate body pH
- kidneys regulate body pH by conserving base bicarbonate and eliminating H+ - eliminated H+ by 3 buffers in the urine (bicarbonate, phosphate, and ammonia)
What are 3 endocrine functions of the kidney?
1. control blood pressure through the renin-angiotensin mechanism 2. regulates RBC production through the synthesis of erythropoietin 3. helps control calcium metabolism by activation of vitamin D
Explain the significance of casts in the urine
casts develop when the protein concentration of the urine is high (as in the nephrotic syndrome), urine osmolality is high, and urine pH is low
Explain how urine specific gravity can be used in evaluating renal function
- healthy kidneys produce a concentrated urine with a specific gravity of 1.030 to 1.040 - with diminished renal function, there is a loss of renal concentrating ability, and the urine specific gravity may fall to levels of 1.006 to 1.010
How are serum creatinine levels used to evaluate renal function?
- as serum creatinine increases, renal function decreases