Urinary Flashcards
Physiology of the Urinary System: Renal function Filtration: Reabsorption: Secretion: Regulation of Urine Volume:
Filtration: of blood into tubules (nonselective: driven by fluid pressure (hydrostatic BP), we lose things we want)
Reabsorption: tubules in the blood (selective: a lot of water, ALL the glucose, Na+ (SODIUM FOLLOWS WATER))
Secretion: blood into tubules (selective: nitrogenous waste- ammonia, H+ (pH), K+)
Regulation of Urine Volume: through ADH, ANH, aldosterone
How much blood is filtered though the kidney?
What is the signif. of this?
20-25% of blood is filtered though the kidney/ min
Shows the importance of a MAP of 60 b/c if it is too high it can cause damage; too low and blood does not get filtered
muscle which forms a layer of the wall of the bladder:? Stimulated by?
Detrusor contraction is triggered by parasympathetic
A triangular area, formed by three openings in the floor of the urinary bladder.
What can occure here?
Trigone: most common place for bladder infection
What is the purpose of pyramids and medulla in the kidney? Renal papilla?
How does dehydration effect this system?
- purpose of pyramids and medulla is to concentrate
urin. Drives the flow of urine
-During dehydration- Fluid becomes more concentrated and thus the more water try to retain in the body
-Renal papilla: where urine flows out of the
pyramids into the cavity
Nephron- The functional unit of the kidney:
Juxtamedullary
Cortical
- Juxtamedullary: long loops of Henle create more concentrated urine more often used during dehydration
- Cortical: shorter loops of Henle
Renal corpuscle consists of what 2 structures?
Glomerulus: ball of filtering tubules
Bowman capsule: surrounds Glomerulus, double membrane
Glomerular filtration membrane (3 layers)
Capillary endothelium
Basement membrane
Capsular epithelium- Filtration Slits
Glomerular filtration membrane: Capillary endothelium Basement membrane Capsular epithelium Filtration Slits
1- Capillary endothelium: outter layer of the capillaries, congruent with basement membrane (innermost of these 3 layers)
2- Basement membrane: inner layer of Bowman’s capsule (the part of the ballooon material touching your fist)
3- Capsular epithelium: Surrounds basement membrane and contains:
-Filtration slits:
(like a colander) collects CELLS which are too large to fit epithelium; and PROTEINS that we do not want to pass into urine. Proteins are small enough to fit through the epithelium but via a shared negative charge they are repealed (like charges repel)
Filtrate passes through the three layers and forms the primary urine
Juxtaglomerular apparatus (JGA): where is it located in the nephron function
Consists of the distal tubule (macula densa cells) and where it touches the afferent arteriole coming out of the glomerulas.
-detects changes in blood flow and pressure to the body system
Macula densa (MD) what that are/ located function
Are cells located in the distal tubule where it touches the afferent and efferent arterioles coming out of the glomerulas.
They detect changes in Pressure (BP) and Na+ (osmotic pressure) from the afferent arteriole.
If BP and Na+ decrease that triggers the activation of JG
Juxtaglomerular (JG) cells
what it is/ located
function
Cells between the afferent arteriole and the MD
Renin secretion (RAAS): which regulates the body’s water balance and BP level
Renal tubules: Proximal tubule Loop of Henle Distal tubule Collecting duct
Proximal tubule: primary site for reabsorption of Na+, 100% glucose, and water
Loop of Henle: reabsorbs the rest of water and Na+ via concentration
Distal tubule: secretion of hormones, gets rid of H+, ammonia, K+
Collecting duct: Water and; ECV regulation…reabsorb H20/Na+
pH regulation …HCO3- and H+
Regulation of Urine Volume (3 hormones)
RAAS
ADH
Natriuretic peptides (ANH)
Function of:
RAAS
ADH
Natriuretic peptides
Renin Aldosterone Angiotensin system (RAAS): works to maintain a low blood volume low BP state in the body.
-starts with the release of renin in kidneys
ADH: pulls water back into blood stream
Natriuretic peptides: promote water and Na+ loss to help lower blood volume and pressure (works opposite from RAAS and ADH)
Function of Filtration
Hint: after afferent, before efferent
Movement of water and protein-free solutes from the blood plasma of the glomerulus (Filtration slits stop cells and proteins from passing into urine)
Across the glomerular capsular membrane into space of Bowman’s capsule
The NFP is determined by the 4 different concentration gradients / pressures that exist in the kidney:
Net Effective Filtration Pressure:
- GHP (glomerular hydrostatic pressure)
- GOP (glomerular onoctic pressure)
- CHP (capsular hydrostatic pressure)
- COP (Capsular Osmotic Pressure)
Equation for:
NFP
NFP = GHP – (Glomerular OP + Capsular HP)
GHP must be > than GOP + CHP (why we need MAP >60)
- GHP (glomerular hydrostatic pressure)
- GOP (glomerular onoctic pressure)
- CHP (capsular hydrostatic pressure)
- COP (Capsular Osmotic Pressure)
- Obstruction
- GHP (glomerular hydrostatic pressure): Systemic blood pressure and resistance in the glomerular capillaries. Pressure that drives out of blood into sac. Decreasing GFR
- GOP (glomerular onoctic pressure): pull of fluid back into glomerular driven by albumin
- CHP (capsular hydrostatic pressure): push of fluid out of capsule
- Capsular Osmotic Pressure: negligible amount (b/c no proteins in the capsule to attract osmotic pressure)
- Obstruction that causes fluid to back up, can cause a reduction of filtration (resulting in kidney stones)
GFR
what it is
what its rate is changd by (2)
Glomerular Filtration Rate (stable)
GFR is the rate of movement of fluid out of the glomerulus and into the capsular space.
GFR is directly proportional to the NFP but can also be changed by:
- Vasodilation / vasoconstriction of the afferent and efferent arterioles
- Changes in Systemic Blood Pressure
We want GFR to be stable over time, but BP is always changing. How is vasoconstriction/ dilation used to maintaine stability?
BP decreases= afferent dilates, efferent constricts
BP increases= afferent constricts, efferent dilates
Reabsorption:
what it is
what is being absorbed
where is absorption happening
Tubular reabsorption is the movement of ions out of various segments of the tubule back into the blood
Water, electrolytes, glucose, amino acids
Via the peritubular blood vessels (travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron)
How does reabsorption take place?
As the filtrate moves through the renal tubule, the concentration of the filtrate changes.
As it moves deeper into the medulla, the osmolarity (concentration) increases, and when it ascends the loop of Henle, it decreases, then once again increases while going down the collecting duct.
This “roller coaster” drives the concentration of urine and the reabsorption of Na+ and water back into blood.
What allows for passive transport of water and Na+?
What is Countercurrent Exchange
The hyperosmotic condition in the medulla (desending loop of Henle)
Hyperosmotic: hyper=“excessive,” and osmos= “push”
Countercurrent Exchange: reabsorption of H2O. Transport of NaCl (without water) in the thin and thick ascending limb of the loop of Henle
Secretion
what it is
what is secreted
Tubular secretion is the movement of substances from the peritubular blood and renal tissues into the renal tubule for removal in urine
Secretion of H+, K+, NH3/NH4+, urea
Concentration and Dilution of Urine (5)
Urea Aldosterone Antidiuretic hormone (ADH) Natriuretic peptides (ANH and others) Diuretics
Urea Aldosterone Antidiuretic hormone Natriuretic peptides Diuretics: increase urine output and thus dilution
1- Urea: nitrogenous waste, ALSO important for regulating urine function
2- Aldosterone: Pulls Na+ and water from urine back into blood. Urine volume goes down, concentration goes up, blood volume goes up, BP increases
3- Antidiuretic hormone (ADH): works in the DCT and CD to pull water out of urine into blood. Urine volume goes down, concentration goes up, blood volume goes up, BP increases, osmotic pressure increases
4- Natriuretic peptides (ANH and others): promote peeing out Na+ and water. Urine volume goes up, urine concentration goes down, blood volume goes down, BP decreases. Blocks the effects of RAAAASTAA
5- Diuretics: increase urine output and thus dilution
RAAS:
what is stands for
what it does
what it is activated by
Renin-Angiotensin-Aldosterone System
- A multi organ system that comes together to help the body have a low blood volume low BP state in the body.
- starts with the release of renin in kidneys
RAAAASTAA
what it stands for
R- Renin A- Angiotensinogen A- Angiotensin I A- Angiotensin Converting Enzyme (ACE) A- Angiotensin II S- Systemic Vasoconstriction* T- Thirst A- ADH A- Aldosterone*
Acidification of urine:
what is the pH range of urine (what about the body)
Hydrogen excretion for acidosis/ alkalosis
Ammonia excretion- its pH is controled by what
4.6-8.0 (body pH: 7.35-7.45)
Acidosis= increase H+ secretion/ decrease HCO3 Alkalotic= decrease H+ secretion/ increase HCO3
Liver converts into urea, taking away pH nature
Renal hormones (4):
Urodilatin (natriuretic peptide)
Vitamin D
Erythropoietin (EPO)
Renin
What do they do? Urodilatin Vitamin D EPO Renin
Urodilatin (natriuretic peptide)
Inhibits sodium and water reabsorption
lower BV/ BP
Vitamin D
Necessary for the absorption of calcium and phosphate
Erythropoietin (EPO)
Released when decreased oxygen to the kidney
Renin