Flashcards in Chapter 16: Renal System Deck (20):
Fluid in body – 60% of body weight
Intracellular fluid (ICF) – 40% of body weight,
Extracellular fluid (ECF) – 20% of body weight,
Interstitial fluid (IF) – 15% of body weight,
Blood plasma (BP)– 5% of body weight,
If your weight is 70 Kg, your fluid is:
ICF = 70 Kg X 0.40 = 28 Liters,
ECF = 70 Kg X 0.20 = 14 Liters,
IF = 70 Kg X 0.15 = 10.5 Liters,
BP = 70 Kg X 0.05 = 3.5 Liters.
Fluid in BP – determines blood pressure!
Renal Cortex Range
~ 300 mOsm
Isotonic to blood
Renal Medulla Ranges
~300 - 1400 mOsm
hypertonic to blood
Blood plasma is filtered through the glomerulus-capsule membrane, the fluid that moves into the Bowman’s space is called filtrate.
Processes in Blood Filtration and Urine Formation
First step in blood processing, occurs in the renal corpuscles:
Water and solutes filter into bowman’s capsule, through glomerular-capsular membrane.
Glomerular Hydrostatic Pressure (GHP)
+ 60 mmHg. Forcing filtration. Increased GHP increases filtration/fluid in urine.
Glomerular Oncotic Pressure (GOP)
- 32 mmHG. Against filtration. Increased GOP decreases filtration/less fluid in urine. Albumin changes
Bowman's Hydrostatic Pressure (BHP)
-18 mmHg. Against filtration. Increased BHP decreases filtration/less fluid in urine.
Reabsorption at Proximal Convoluted Tubule
First part of renal tubule nearest to Bowman’s capsule,
Follows a winding, convoluted course,
Reabsorption: movement of molecules OUT of the tubule and INTO blood. Water, electrolytes and glucose are reabsorbed through secondary active transport dependent on Na+ gradient set-up by Na+/K+-ATPase pump.
Reabsorption in Loop of Henle
Water conservation process: Counter-current mechanism filtrate concentration
Separates reabsorption of water and solutes.
Permeable to water
Permeable to NaCl, but NOT water,
Last segment hypotonic (100 mOsm/L) to ECF
Reabsorption by Distal tubule and Collecting Duct
DT and CD Function in water conservation, solute and pH balance
A small amount of solute reabsorption
functions in Na+ reabsorption
Antidiuretic hormone (ADH)
functions in water reabsorption
function in decreasing Na+ reabsorption
Function in pH balance – in acidosis secrete H+ in alkalosis conserve H+.
Tubular Secretion in Distal tubule
Distal Tubule: MOST secretion by mass
Primarily K+, H+
Proximal tubule – small amount
Cellular transporters – transport blood hormones, metabolites, medications, toxins, etc
Compensation for Hypertension
Atrial natriuretric hormone (ANH) - secreted by specialized cardiac atrial and ventricular muscle fibers
Promotes ↑[Na+] in urine ↑H2O in urine ↑urine volume ↑H2O loss, (opposes Aldosterone).
Secreted in response to ↑blood pressure or ↑blood volume.
Compensation for Hypotension
ADH secreted by hypothalamus influences water reabsorption:
↑H2O reabsorption ↓urine volume preventing water loss.
Aldosterone: activated by the RAAS (renin-angiotensin-aldosterone system) mechanism
↑Na+ reabsorption in distal tubule ↑[Na+] in blood ↑ H2O reabsorption into blood.
RAAS (Renin, Angiotensin, Aldosterone)
For hypotension. Renin (kidney) + Angiotensin-converting enzyme (ACE) (Liver) = Angiotensin 1 (Lungs) --> Angiotensin 2 --> Aldosterone --> Salt + Water Retention/Vasoconstriction