Urinary system Flashcards
Function of urinary system
Regulate blood volume and blood pressure • Regulate plasma ions, such as sodium, potassium, chloride, and calcium • Aid in stabilization of plasma pH • Conserve valuable nutrients like glucose and amino acids • Eliminate wastes like urea and uric acid,creating,drugs, toxins
Where kidneys are found
In retroperitoneal space, outside the peritoneum cavity
What does supply kidneys with blood
Renal arteries
How much blood do kidney have at any time
20-25% of the cardiac output
What is part of urinary system
Urinary bladder
Kidney
ureter (connecting kidneys and bladder)
Urethra
What is blood osmolarity
290 OsM
The body’s integrated
responses to increased
blood volume and blood
pressure
Increased blood volume-“ increased blood pressure
Increased BP-“volume receptors in atria,endocrine cells in atria and carotid and aortic baroreceprtors trigger homeostatic reflexes: causing heart to decrease output and to vasodilate
And kidneys to excrete salts and H2O in urine-> decreased ECF and ICF volume->decreased BP
How body responses to decreased blood volume and decreased blood pressure
In heart the opposite of increased BP
Behavior: increased thirst->incresed water intake->increased ECF and ICF, kidneys conserve H2O
Functional unit of kidney is
Nephron
Parts of kidney
Renal cortex, renal medula, renal pyramid,renal pelvis, calyx which are connected to renal pelvis
distribution of nephrons between cortex and medulla
80% of the nephrons in the kidney are almost completely contained within the cortex and the other 20 % dip down into the medulla
What part of the nephron is in the medulla and cortex
Cortex- corpsule, some tubules
Medulla-collecting duct,nephron loop
What blood vessels lead into the glomerous
cortical radiate arteries
2 components of nephron
Vascular component
Tubular component
Vascular route in nephron
1.On entering the kidney the renal artery –afferent
arteriole, brings blood to the afferent arterioles
which deliver blood to the…
2. glomerulus to be filtered. Efferent arteriole
transports blood from glomerulus
3.Efferent arteriole breaks down into peritubular
capillaries which surround tubular part of
nephron and supply the blood for the exchange
with the fluid in the tubular lumen
4.Peritubular capillaries join into venules which
transport blood into the renal vein which is the
way by which blood leaves the kidneys
The nephron tubular component begins with ball-like structure known as
___
Bowman’s capsule
Histology/structure of glomerulus and bowman’s capsule
The endothelium of the glomerulus is fused to the epithelium of the
capsule allowing the fluid being filtered to pass directly in ot the lumen of
the tubule.
structure of the nephron
Glomerulus+bowman’s capsule
Proximal tubule
Helenie’s loop or nephron loop: descending,henle’s loop and ascending limb
Distal convoluted tubule leading to collecting tubule
What plays a role in controlling the pooling activity in the kidney
The osmolaric gradient in medulla
How much plasma that enters glomerulus is not filtered
extracts from the 80% unfiltered in
the peritubular capillary->venous system
Urine results from 3 processes
1. Glomerular filtration- non discriminant, except blood cells and plasma proteins all constituents within the blood are filtered 2. Tubular reabsorption- highly selective movement of filtered substances from the tubular lumen into the peritubular capillariesconserved for body of value kept 3. Tubular secretion: selective movement of non-filtered substances from the peritubular capillaries into the tubular lumen- for excretion -This provides a second route for substances to enter the tubules for excretion in addition to the GF
What is done to favor the filtration in glomerulus
afferent Arterial diameter is bigger efferent one-> blood pressure
solutes are transported in/out tubular fluid via
transport proteins
What cell layers the liquid need to pass in order to get through glomerulus
1) the pores between the endothelial cells of the glomerular capillary
2) an acellular basement membrane
3) the filtration slits between the foot processes of the podocytes of the inner layer if bowman’s capsule
Fluid filtered from the glomerulus
into Bowman’s capsule must pass
through three layers of the
glomerular membrane
- Glomerular capillary wall
- Basement membrane
- Inner layer of Bowman’s capsule
Glomerulus pressure vs filtration pressure
g: 55 mm HG
filtration: 10 mm
Fluid moves from high presssure to low presssure area which in the glom is further facilitated by the high permeability partially mediated by the filtration slits and thinness of the capillary wall in the glom.
what other pressure is created by the plasma in glomerulus
Plasma-colloid osmotic pressure Oppositional force • larger plasma proteins can not be filtered across the glomerulus membrane and enter into BC • unfiltered proteins exert a colloid osmotic pressure on the filtered fluid in the BC
3rd pressure in the kidney during the filtration
Fluid pressure in Bowmans capsule opposes filtration • This opposing pressure can increase in the case of a blockage
What is GHP,BCOP,NFP,CsHP
GHP-glomerular hydrostatic pressure
BCOP-blood colloid osmotic pressure
NFP=net filtration pressure
CsHP-capsular hydrostatic pressure
What drives the solutes out of the nephron
in the nephron loop this is increasing osmolaric pressure
in collecting duct - it is hormones and reabsotprion in collecting duct
what is absorbed at each step of the kidney reabsorption
Proximal tubule-some solutes are actively transported back into the blood:nutrients, NaCl
Passively:HCO3-,H2O,K
Inside the proximal tubule: actively-H+, passively-NH3
Descending limb of loop of Henie is permeable only to water-> water out to medulla-> increased osmolaric pressure inside the limb
Thin segment of ascending limb (right after the turn)->passive transport out of NaCl, not water
Thick sigment->active transport of NaCl
In distal tubule:active transport in:K,H, out-NaCl,HCo3-
Passively out H2O
In the collecting duct by osmosis, allowing salty urine to exit . H2O passively out, urea passively out
Histology of descending and ascending limb
Ascending is much thicker and limits the diffusion of most molecules
What is the difference between collecting duct and the loop of henlie if the have the same osmotic pressure
The collecting duct is the structure that makes concentrated urine; the loop of Henle just maintains the osmotic gradient.
How the level of urine is adjusted in the nephron
Water permeability of collecting duct is adjustable. -More permeability means more water reabsorption; saltier urine. - Permeability is adjusted by adding or removing aquaporins-This is how ADH acts on kidney
What is glomerular filtration rate
Amount of filtrate produced by
kidneys/minute
– Average is 125 mL/min or 180 L/day
– 99 percent reabsorbed in renal tubules
GFR is dependent on
– Maintaining adequate blood flow to kidney
– Maintaining adequate net filtration pressures
What is key to maintain kidney function
Maintaining net filtration pressure and
consistent GFR is necessary for normal
kidney function
GFR is regulated by
- Autoregulation (or local regulation)
- Hormonal regulation
- Autonomic regulation
• Through sympathetic division of ANS
Factors affecting vasopressin release
Osmolarity greater than 280 mOsM (hypothalamic osmoreceptors)
Decreased atrial stretch due to low blood volume (atrial stretch receptor)
Decreased blood pressure (carotid and aortic baroreceptors)
Vasopressin is released from
posterior pituitary
Action of vasopressin
Insertion of water pores in apical membrane in collecting duct epethilium-> increased water reabsorption to conserve water
Vasopressin acts through what biochemical signalling
cAMP
How autoregulation of renal blood flow happens
1.Myogenic regulation.
When arterial pressure increases the renal afferent arteriole is
stretched. Vascular smooth muscle responds by contracting
thus increasing resistance-> decreased urinary flow
What are granular cells, macula densa and regulation of tubuloglomerular feedback
•At the fork (made by afferent and efferent arterioles) there are specialized smooth muscle cells in the wall of the afferent arteriole, these are called granular cells. •There are also specialized tubular cells in this region are called the macula densa. The macula densa act to detect changes in salt level in the fluid passing by them.( ascending limb of loop of henle, connecting to the distal tubule) • If more fluid is passing through the tubule-more salt is detected and the Macula densa release adenosine. •Adenosine acts as a Paracrine regulator causes vasoconstriction at adjacent granular cells
Autoregulation: tubuloglomerular feedback summary
GFR increases->Flow through tubule increases->NaCl flow past macula densa increases->paracrine factor adenosine from macula densa to afferent arterioles->afferent arteriole constricts->resistance in afferent arteriole increases->hydrostatic pressure in glomerulus decreases->GFR decreases
What part of the nephron forms
the juxtaglomerular apparatus?
- Bowman’s capsule
- Where the collecting duct joins the ureter
- Where the ascending limb of henle joins the distal
tubule - Where the proximal tubule joins the descending limb
- Where the descending limb joins the ascending limb
3
What happens to GFR when the
afferent arteriole dilates?
It increases
The plasma is most similar in chemical
composition to the fluid in the _______.
- proximal tubule
- collecting duct
- distal tubule
- Bowman’s capsule
- ascending limb of the loop of Henle
4
What does it mean filtration, reabsorption, secretion and excretion in regards to nephron
Filtration: blood to lumen (in glomerulus)
re-absorption: lumen to blood
Secretion: from blood to lumen
Excretion: lumen to external environment ( out of collecting duct to the bladder)
“Secretion” in a nephron
always refers to transport of
________.
- water into the nephron lumen
- water out of the nephron lumen
- a solute into the nephron lumen
- a solute out of the nephron lumen
3 or water as well
How ADH influences the collecting duct
It increases the reabsorption of water because of extra waterporins inserted->small volume of concentrated urine
What will happen if you ingest high salty meal?
No change in volume, but increased osmolarity-> vasopressin secreted-> increased water reabsorption->kindneys conserve water
Increased osmolarity->thirst->increased water intake-> increased ECF-> increased blood pressure
Increased ECF->Kidneys excrete salt and water (slow response)
Increased BP->CV reflexes lower blood pressure (rapid response)
What happens when the body needs salt?
Aldosterone combines with a cytoplasmic receptor in P cell of distal nephron
- Nephron-receptor complex initiates transcription
- Translation and protein synthesis-> new protein channels and pumps, increase Na and K channels open time
- Na ATPase pump speeds up
- Result is increased Na reabsorption and K secretion
Aldosterone produced in ___, acts on ___
adrenal
Principal cells in the distal tubule
What is RAAS
The renin-angiotensin-aldosterone system
In response to the blood pressure
What is renin and when it is secretedd
In response to decreased BP granular cells in kidney release renin that converts angiotensinogen in the plasma to ANGI
What will happen to ANGI in plasma
ACE enzyme that is in blood vessel endothelium cells in the lungs will convert ANGI to ANGII
What is the role of ANGII
To vasoconstrict arterioles
To increase CV response influencing medulla oblongata
To increase vasopressin and thirst acting on hypothalamus
Increase aldosterone by influencing adrenal cortex
What is ANP
Atrial Natriuretic Peptide (ANP)
• Antagonist to aldosterone
• Increases water loss. This is regulatory system of
Blood pressure. Would be produced in the case of
high blood pressure
How ANP works
ANP Inhibits Na+ reabsorption
• Secreted by atria in response to being stretched by Na+
retention, expansion of ECF volume, and increase in
arterial pressure
• Release inhibits Na+ reabsorption in the distal tubule
which increases Na+ output in urine
• Increase GFR-more water loss
• Inhibits renin secretion by the kidneys.
• hypotensive effects to help correct the original stimulus
that brought about release of ANP
What is one target for decreasing high blood pressure
inhibit angiotensin converting enzyme
Target of ANP
decrease Na reabsorption by kidney tubules
decreasevSalt-conserving renin-angiotensin aldosterone system
Smooth muscle of afferent arterioles-> afferent arteriolar vasodilation
Decrease sympathetic nervous system-> decreased arterial blood pressure
How coffee influences kidney
Coffee blocks ADH->decreased water reabsorption to conserve water-> increased peeing with dilute urine
Causes of renal failure
-Infectious organisms – Toxic agents – Inappropriate immune responses – Obstruction of urine flow – An insufficient renal blood supply
After drinking a large volume of water, compensation is
primarily achieved by a decrease in the level of the
hormone ______.
1.aquaporin
2.aldosterone
3.vasopressin
4.atrial natriuretic peptide
Vasopressin
hypertension and how it can influence the kidneys
persistent HBP->renal arteriosclerosis and atherosclerosis-> reduce blood flow through afferent arteria-> secretion of rennin->increased vasoconstriction-> increased thirst-> making the problem even worse
Fred has chronic emphysema (type of chronic obstructive pulmonary disease. The air sacs in the lungs become damaged and stretched. Body is not able to get read of CO2). Blood tests show that his pH is low almost normal but his H2cO3 levels are elevated significantly-> respiratory acidosis. What is the problem
The kidneys try to compensate for acidosis-> kidney is getting rid of hydrogen ions
Fred has chronic emphysema (type of chronic obstructive pulmonary disease. The air sacs in the lungs become damaged and stretched. Body is not able to get read of CO2). Blood tests show that his pH is low almost normal but his H2cO3 levels are elevated significantly-> respiratory acidosis. What is the problem
The kidneys try to compensate for acidosis-> kidney is getting rid of hydrogen ions-> urine is high hydrogen and low CO3
Aldosterone secretion will be \_\_\_\_\_ by an increase in plasma [K+]. 1.increased 2.decreased 3.not changed
Increased
An 83–year–old woman with severe orthostatic hypotension is given Florinef, a potent aldosterone agonist. In addition to following her blood pressure, what parameter should also be monitored? 1.Heart rate 2.Serum potassium 3.Serum sodium 4.Serum chloride 5.Serum bicarbonate
Serum potassium -> decrease in potassium levels-> can check how the drug is working
The hormone that most directly influences Na+ balance in the body is \_\_\_\_\_\_. 1.vasopressin 2.angiotensin 3.renin 4.aldosterone 5.atrial natriuretic peptide
4
Eating salty dry food without drinking will cause (before any response) a(n) \_\_\_\_\_\_\_\_ in body fluid osmolarity and \_\_\_\_\_\_\_\_ in the volume of the body fluids. 1.decrease; no change 2.decrease; an increase 3.decrease; a decrease 4.increase; no change 5.increase; an increase
4
The vasa recta are the
_______.
1.peritubular capillaries associated with
the loop of Henle
2.osmoreceptors in the hypothalamus
3.kidney cells that produce renin
4.liver cells that produce angiotensinogen
1
different stages of dehydration and symptoms: 2,5,10,12 % of body water loss
2% Thirst Loss of Appetite Fatigue or Weakness Chills Dry Skin Skin Flushing Dark Colored Urine Dry Mouth Head Rushes
5% Increased heart rate Increased respiration Decreased sweating Decreased urination Increased body temperature Extreme fatigue Muscle cramps Headaches Nausea Tingling of the limbs
10% Muscle spasms Vomiting Racing pulse Shriveled skin Dim vision Painful urination Confusion Difficulty breathing Seizures Chest and Abdominal pain Unconsciousness
12%
Clinical shock, unconscious, depressed function of all organs
What happens to Darlene during 14 days without water
Decreased blood volume as water is lost-> decreased blood pressure-> increase of heart rate at first (10% loss) , because the body tries to compensate for the loss
She is conscious but weak when found, weak pulse and low BP
The first hing that rescuers have to Darlene was
Oxygen to save the brain
replenish fluids into the vein
What is 60-40-20 rule
60% of our body mass is water
Extracellular fluid -20% pf body weight (lymph, fluid surrounding brain, plasma,etc.)
Intracellular fluid-40% (cells)
Solid matter- 40% of BW (bone,tissue matter)
Extra cellular fluid components
Interstitial fluid and plasma
What is transcellular compartment
the “third space”-the liquid that is not so easily accessible like spinal fluid, peritoneal, pleura, pericardial cavities, joints, GIT, ocular fluid
Interstitial fluid provides medium for
Transport of gases, nutrients, wastes
Which compartment will be compromised to sustain vascular fluid
IF for the periods of hemorrhage or loss of vascular fluid
IF is supported by
Collagen fibers that opposes outflow of water from capillaries and prevent accumulation of free water
IF is dominated by ___ ions
Na, Cl
When transcellular fluid can be increased
conditions as ascites (large amounts of fluid in peritoneal cavity)
What are the predominant ions inside the cells
K, HPO4, protein- a lot
Mg, Na HCO3-,Cl, So4- -> a little
Plasma cations and anions concentration
Na and Cl - a lot
K,Ca, HCO3, HPO4, organic acid, proteins- a little
Interstitial fluid - ion concentration
Na and Cl a lot
K,HCO3, HPO4, SO4 a little
Where we lose moist
Water vapor lost at skin and lungs - 1.15 L
Water lost in feces
Water secreted by sweat glands
Water lost in urine-1.2 L
Where we get fluid to ECF
from GI
Metabolic eater form cells
How much water should we drink a day considering all the losses
2.2 L
Does water moves freely across the cell membrane
Yes, it follows ion concentration
How much water percent we get from food and drink
from food 40 percent
48 drink
if 40 percent food and 48 drink, where is the rest 12 percent coming from
Metabolic generation
Assuming that darlene did not have access to water during the entrapment , from what sources would her body begin to lose water
Urine
Skin
Gut
Respiratory tract
Loss of electrolyte balance results in
Loss of water balance
Loss of cell function:
Ca and K imbalances affect cardiac muscle tissue
Na and K major contributors to osmolarity of ICF and ECF
How might the body immediately begin to reduce water losses
Osmoreceptors in the hypothlamus detect increase in osmotic concentration and secrete ADH-> increased reabsorption of water from urine
Baroreceptors in the aortic and carotid bodies sense reduced blood pressure -> more firing of sympathetic NS-> more vasoconstriction->increased heart rate-> reduced blood flow to areas of potential water loss would decrease the rate of water loss somewhat
3)activation of RAAS-> increased water reabsorption
Where the blood flow should be decreased in order to minimize water losses
Renal-> dercreased blood flow-> decreased water loss
Gut-> vasoconstriction-> less secretion, less loss In starvation gut function is reduced
Vasoconstriction in skin-> less sweating, but can increase body temperature
Hypometabolic state->reduction of muscle tone and decreased oxidative process->lowered evaporative water from respiratory tract. Less shivering during the night to conserve water
Nervous system blood flow should be maintained to preserve the ability to respond to physiological challenges, mental function becomes compromised
Will the buried girl still pee
Yes, kidneys will work until kidney failure
How the fact that the girl was buried under the building helped her
In a warm, humid environment darlene would have lower respiratory loss+ under the building constant environment-> protection from higher metabolic expenditures and decreased water loss form sweat and shivering
Does age,weight or sex affect water loss requirements
Younger individuals usually weigh less than older ones-> lowered measured daily water loss as energy expenditure is lower
Females usually have higher water loss per unit of energy than males, but smaller bodies->less water loss
Young females can have an advantage of expanded plasma volume due to the influence of estrogen, and if Darlene were in mid-menstrual cycle, with estrogen levels at their peak, she would have has more extracellular blood volume , being capable of coping with prolonged dehydration than a similar sized male
Does the fact that Darlene was born in Haiti matter
Probably because of her origin Darlene exhibited good heat acclimation to the environment. But heat acclimated people sweat more that non-ones, however Darlene’s sweat had less Na, which is important for plasma volume
How darlene survived this prolonged period of starvation, will it use more water
Fat catabolism during starvation produces one gram of water per gram of fat metabolized
what is thought to be the absolute minimum rate of water loss for humans
1.2 liters/day
