Physiology 1 Renal Function Flashcards
What volume of plasma of does the kidney filter per day
180 L
How much filtered water and sodium are reabsorbed
98-99% of the filter water and sodium are reabsorbed
How much of the filtered biocarbonate and amino acids are reabsorbed
virtually all
What is the typical urine output
1-2 L/day
How does the kidney maintain homeostasis across a wide range of physiological conditions
1.) Adjust blood flow to the glomerular capillaries 2.) Adjust glomerular filtration rate 2.) Alter the absorptive capacity of the nephron
Long term regulation of blood pressure
achieved through renal handling of sodium - determines the movement of water and extracellular fluid volume
what drives the system for regulation of effective circulatory volume
Na-K-ATPase (renal handling of sodium that determines the movement of water)
List the functions of the Kidney
1.) Long term regulation of blood pressure 2.) Regulation of plasma ionic compositin, pH and osmolality 3.) Exretion of metabolis end products 4.) Excretion of non-metabolized dietary substances 5.) Activation of vitamin D 6.) Endocrine functions
Describe relationship of dietary intake and excretion at steady state
at steady state intake= excretion
What endocrine functions does the kidney serve
1.) secretion of renin (juxtaglomerular cells ) 2.) Secretion of erythropoietin 3.) Metabolism of hormones and drugs
Effective circulating volume
the pressure in the system- the kidneys can only respond to pressure (interpret low pressure as low volume and begins to reabsorb sodium so that water will follow to increase effective circulating fluid volume)
How does the kidney regular plasma ionic composition and pH
1.) Reabsorption (and or metabolism) of filtered solutes 2.) Secretion of substances leading to excretion 2.) Excretion of daily acid load ( H+ secretion, HCO3- reabsorption and formation of titratable acid and NH4 in urine)
Regulation of plasma osmolality
Determines intracellular fluid volume. ADH-dependent reabsorption of “free water” in the distal nephron- kidney has the ability to conserve water and procuse a concentrated urine by retaining free water
where is renin released
Renin is released from afferent arteriaoles- acts in the Renin-Angiotensin-Aldosterone cascade
When is erythropoeintin released
in chronic hypoxemia (EPO increased the production of RBC)
When is urodilin released
in response to increased ECV
Active calcium regulation in the kidney
Activation of vitamin D in response to parathyroid hormone (low plasma Ca2+)
When are nateuritic factors released
in hypervolemic states- increase sodium excretion to get rid of water
what is the functional unit of the kidney
nephron (1,000,000 per kidney) Types: Cortical and Juxtamedullary
Describe the arrangement of glomerular capillaries within a renal corpuscle- what is the consequence of this
arranged in parallel- low resistance and high surface area
What are the resistance vessels of the renal corpuscle
Efferent arteriole
What allows for the high filtration rate in the glomerulus
two arteriles in series (affternt arteriole to glomerlar capillaries to efferent arteriole)
Proximal Tubule
Cuboidal cells with brush border, many mitochondria, and basolateral invaginations = High Reabsorptive capacity
Describe the reabsorptive capacity of the proximal tubule
Reabsorbs 65% of filtered sodium and water and nearly all of the bicarbonate, glucose, phosphate,and amino acids
What are the physiologically distict regions of the loop of henle
1.) Thin descending segment 2.) Thin ascending segment 3.) Thick ascending segment
Three functionally distinct segments of the distal nephron
1.) Distal tubule 2.) Connecting segment 3.) Collecting tubule
Cortical connecting tubule cell types
1.) Connecting tubule cells (produce and release kallikrein) 2.) Intercallated cells ( involved in handling H+, HCO3, and K+)
Cortical collecting tubule cell types
1.) Principle cells ( handling Na and K) 2.) Intercalated Cells ( involved in H+, HCO3, and K)
Sympathetic respone
Blood vessels constrict, Juxtaglomerular cells (B1) release renin
Effect of increased sympathetic tone on reabsorption of solute and water
increased sympathetic tone causes increased absorption of solute and water
Is excretion a function of the nephron
NO the nephron can filter, reabsorb and secrete
Glomerular filtration
Water and solutes (up to 5000 MW) are freely filtered - plasma proteins are NOT freely filtered
Average GFR
~125 ml/min or 180 L/ day ( passing your plasma volume through your kidneys 60 times a day)
Tubular reabsorption
solutes and water that have been flitered mover OUT of the tubula rlume and ultimately enter the peritubular capillaries through 1.) Paracellular route (between cells - through intercellular junctions) 2.) Transcellular route (aquaporins in luminal and abluminal membranes
Mechanisms of solute reabsorption
1.) Passive Diffusion (down a concentration gradient) 2.) Passive transport (facillitated diffusion) 3.) Active transport - Primary and Secondary
Co-transport (Symport)
two substances move in the same direction across a cell membrane ( down concentration gradient for one - ex: Na-Glucose, 2NA-Phosphate)
Counter-transport (Antiport)
Two substanced move in OPPOSITE direction cross the membrane (down the concentration gradient for one of them) Ex: Na-H
What makes water move
Osmotic gradient- water follows soulte
Tubular secretion
solutes move INTO the tubular lumen from tubular cells or the interstitial space/peritubular capillaries. Important for the excretion of NH3, metabolic biproducts, drugs, and chemicals
Describe the Reabsorption and Secretion of Inulin and Creatinine
Freely filtered, Not reabsorbed, not secreted
Describe the reabsorption and secretion of urea and phosphate
freely filtered, partially absorpbed, not secreted
Describe the reabsorption and secretion of glucose
Freely filtered, ALL reabsorbed, not secreted
Descrive the reabsorption and secretion of PAH
Freely filtered, not reabsorbed, ALL secreted
Starting forces of glomerular capillaries
hydrostatic > oncotic resulting in filtration
Starling forces in preitubular capillaries
oncotic> hydrostatic resulting in reabsorption
