Chapter 26 -2 Flashcards
(25 cards)
Reabsorption
Movement of material (nutrients) from urine to blood
Glomerular formation
-occurs in glomerulus within bowman’s capsule
•decreased diameter of afferent blood vessels generates increased BHP forcing material out of blood
•increased BHP largely determined by blood pressure
•filtration is indiscriminate all material in blood (nutrients and waste) are forced out and collected by bowman’s capsule
Tubular reabsorption
-Occurs in proximal tubule
• 99% of of original filtrate reabsorbed
• nutrients move by diffusion back into blood
•Tubular transport maximum = upper limit on amount of any nutrient that can be reabsorbed
Obligatory Reabsorption
-occurs along loop of Henle
•water absorbed by osmosis on descending loop
*amount of water reabsorbed determined by length of descending loop
• sodium reabsorbed by diffusion and active transport on ascending loop
Facultative reabsorption
-Occurs in distal tubule
•only occurs under special circumstances (e.g. Dehydration)
•hormones alter permeability of distal tubule
•increased permeability allows for increased reabsorption of water and sodium
Tubular secretion
-occurs in distal tubule
•1:1 exchange of potassium (K+) for Sodium (Na+)
• hydrogen (H+) secreted for pH regulation
Filtration
Manipulate blood pressure
Juxtaglomerular cells
Vasodilate afferent blood vessel
Renin-Angiotensin Pathway
Angiotensin causes vasoconstriction of efferent blood vessels
JG cells release
Renin
Renin converts Angiotensinogen into
Angiotensin
Angiotensin has broad effects in body to elevate
Blood pressure
Anti-diuretic hormone (ADH)
Causes increased water absorption
Aldosterone
Causes increased NA+ reabsorption
Angiotensin release
•Both ADH and aldosterone (both hormones)
* by-product of effects is an increase in blood pressure
Renal Clearance
Rate at which a particular substance is cleared from the blood
Renal Clearance (RC) =
UV/P
P =
Construction of substance in blood (plasma)
U =
Concentration of substance in urine
V =
Urine flow rate (rate at which urine is created)
Total time to clear substance =
•P/RC
Ex: *ammonia (NH4+) in blood = 10mg/ml (p)
* ammonia in urine = 2 mg/ml (u)
* flow rate = 0.1 ml/min (v)
• RC = 2(0.1)/10 = 0.02mg/ml/min
• total time 10/0.2 = 500 mins
Uremia
-failure of renal clearance
•build up of urea in the blood
• can lead to septic shock
Gout
-Failure of renal clearance
• build up of Uric acid in blood
• Uric acid crystallizes and is deposited into the joints
Renal calculi
-Kidney stones
• salts (e.g. Calcium) crystallizes in urine
• impede flow of urine
• generates pain as scrape urinary tract during passage out of body
