renal Flashcards
What is the role of the renal system
Excretion
Water/electrolyte balance
pH regulation
Control of circulating volume
What vertebra level are the kidney located at
L1-L4 when standing
What is the inner portion of the kidney
Medulla
What is the outer part of the cortex
Medulla
What cord level innervates the kidneys
T12
What does sympathetic stimulation of the kidneys do
Constriction of arterioles
decrease flow of fluids = decreased output
Increase sodium reabsorption
Increase renin release
how many capillary beds does the kidneys have
2 capillary beds
What are the two capillary beds in the kidneys
Glomerular capillaries
Peritubular capillaries
What is the order of kidney blood flow (in)
Afferent arterioles
Glomerular capillaries
Efferent arteriole
peritubular capillaries
What causes the rapid fluid filtration at the glomerular capillaries
High hydrostatic pressure
What allows for rapid fluid reabsorption at the peritubular capillaries
Low hydrostatic pressure
What are the two different nephron structures
Cortical nephron
Juxtamedullary nephron
What is the difference between cortical and juxtamedullary nephron
Juxtamedullary nephron is longer and penetrates deeper into the medulla
Can the kidney regenerate new nephrons
No
how many functional nephrons do you lose each year
10% every 10 years
does filtration effectiveness change as we age/lose nephrons
no
what encases glomerular capillaries
Bowman’s capsule
What type of nephron is most common
Cortical
what nephron is surrounded by Vasa recta
Juxtaglomerular
what precent of nephrons are juxtaglomerular
20-30%
how much does the pressure in the urinary bladder increase by when detrusor muscle contracts
40-60 mmHg
What part of the urinary bladder do the ureters enter
The upper trigone
Where is the trigone of the bladder located
The posterior wall
What is special about the surface of the trigone
It is smooth muscle with no rugae
What prevents backflow of urine into the ureters
THe tone of the detrusor muscle
Is the external urinary sphincter voluntary or involuntary
Voluntary
What nerve innervates the external urinary sphincter
The pudendal nerve
what cord levels provide parasympathetics to the urinary bladder
S2
S3
Via sacral plexus
What is the order of urine flow
Nephron Collecting ducts Renal calyces Ureters Bladder
What is the Ureterorenal reflex
When there is pain in ureters renal arterioles constrict and decrease flow of fluid to kidneys
The ureterorenal reflex sends sympathetic or parasympathetic signals to the kidneys
Sympathetic
What is micturation
The process of emptying the bladder
What does it mean by the micturation reflex is self-regerative
Contracture of the detrusor muscle causes further activation of the stretch receptors
The longer you hold it in you will feel more pain and the sensation to pee will come back faster
What happens to micturation reflex as the bladder fills
Increase frequency of reflex
Increase intensity of reflex
Can the micturation refelx affect the external sphincter
Yes, and eventually the relaxation of it will be involuntary if held too long
What starts the micturation reflex
Sensory stretch receptors in the bladder wall
What is the average amount of fluid excreted via kidneys each day
1400ml/day
What are the parts of extracellular fluid
Interstitial fluid
Blood plasma
Transcellular fluid
what ions are high and low in intracellular fluid
Low= sodium, calcium, chloride High= potassium, phosphate
what ions are high and low in extracellular fluid
Low= potassium, phosphate, proteins high= sodium, chloride, bicarbonate
what is the definition of Osmolarity
Osmoles per liter of water
what is it called when a solution has a lower concentration of solutes than the cell
Hypotonic
What is it called when a solution has a higher concentration of solutes than the cell
Hypertonic
What is the most variable source of water loss from the human body
Urine
what type of blood vessels deliver blood to the renal corpuscle
Afferent arteriole
what should not filter out of the blood under normal circumstances
Red blood cells and plasma proteins
What is special about the membrane of glomerular capillaries
They have 3 layers instead of two
What prevents the passage of plasma proteins in the glomerular capillaries
The endothelium is negatively charged
What part of the basement membrane has a strong negative charge that prevents proteins from passing though
The proteoglycans
Is the epithelium layers of the renal corpuscles negativley charged
yes
What allows for filtration in the bowmans capsule
Blood colloid osmotic pressure caused by proteins
What is renal plasma flow
Volume of blood plasma delivered to the kidneys
What is Filtration Fraction
Proportion of the fluid reaching the kidneys which passes into the renal tubules
What is the average filtration fraction
20%
What is the average renal plasma flow
550 ml/min
How can renal plasma flow be altered
Increase overall cardiac output
Dilate afferent arterioles
How can Filtration Fraction be altered
Contract efferent arterioles, increasing glomerular pressure
What causes/favors filtration
Glomerular hydrostatic pressure 60mmHg
Bowman’s capsule colloid osmotic pressure 0mmHg
What causes/inhibits filtration
Bowmans capsule 18mmHG
Glomerular cap colloid pressure 32mmHg
What is the equation to calculate Filtration fraction
FF=GFR/RBF
What happens to glomerular filtration when membrane permeability decreases
it decreases
What happens to GFR when bowmans capsule pressure increases
Decrease GFR
What happens to GFR when Glomerular colloid pressure increases
Decreases GFR
What happens to GFR when Glomeular hydrostatic pressure increases
Increase GFR
What happens to GFR when arteriol pressure increases
GFR increases
Dilation of afferent arterioles will do what to GFR
Increase GRF
What part of the kidney receives most of the renal blood flow
The cortex
What supplies the Renal medulla with nutrients
The vasa recta
What does Angiotensin II do to the kidneys
Maintain GFR when BP drops (prevents drop in GFR)
What changes to filtration when Angiotensin II is released
Increase reabsorption of sodium and water
What happens when renal cells sense a decrease in sodium concentration
Decrease blood flow in afferent arterioles (increase GFR)
Renin released (increase GFR)
Filtration and reabsorption are high/low compared to excretion rate
High
What is excretion rate equal to for electrolytes
Filtration rate - reabsoption rate
What does it mean when excretion rate = 0
NO exretion in the urine
What is excretion rate equal to for organic acids and bases, foreign substances, and drugs
Filtration rate + secretion rate
What happens if the basement membrane loses its electrical charge
Albumin is filtered and will be in urine
What is vital in determining excretion rate
Tubular reabsorption
What is more selective; Glomerular filtration or Tubular reabsorption
Tubular reabsorption is more selective
What are the steps of tubular reabsorption
Transported across the epithelial membrane
into interstitial fluid
through peritubular membrane
into blood
What can travel through tubular epithelium
Water and solutes
Where is sodium transported
Proximal tubule
What type of transport is required to transport sodium from the proximal tubule cells into the interstital fluid
Active transport via sodium potassium ATPase pump
What transports glucose into cell against concentration gradient
SGLT2
SGLT1
What process allows for the movement of glucose
Release of energy from ATP (secondary active transport)
What is counter transport in the kidney
Secretion of a substance into the tubule by secondary active transport
What substances do not demonstrate a transport maxium
Substances that are passivly absorbed
Which is greater:
Maxiumum transport capacity of basolateral sodium ATPase pump
Or
THe actual rate of sodium reabsorption
The maximum transport capacity of basolateral sodium ATPase pump
what is the limit to the rate at which a solute can be transported during active reabsorption or secretion
Transport maximum
How are proteins and amino acids reabsorbed in the kidneys
Pinocytosis
What percent of filtered water and sodium is reabsorbed
65%
What can transport sodium across a cell
Co-transporters
Counter-transport mechanism
Sodium-potassium ATPase pump
What allows the proximal tubule to keep a constant osmolarity
It is highly permeable to water
What is secreted in the proximal tubules
Organic acids + bases
Drugs + toxins
What is the primary function of the thin desceding segment of the loop of henle
Allow for simple diffusion
What happens in the thick ascending segment of the loop of henle
Active reabsorption of sodium, chloride and potassium
Can water pass in the thick ascending loop of henle
No
What is the first portion of the distal tubule called
Macula densa
What % of sodium is absorbed in the proximal distal tubule
5%
What is the job of Principal cells
Sodium reabsorption
Postassium secretion
What is the job of intercalated cells
Hydrogen secretion
Bicarbonate+potassium reabsorption
What determines water permability in the distal tubules
ADH (Vasopressin)
high=high permeability
low=low permeability
What is water reabsorbtion dependent on in the medullary collecting ducts
ADH levels
What portion of the loop of henle do we significant sodium transport
Thick ascending
How has osmolarity changed when the filtrate reaches the end of the proximal tubule
Stayed the same
high permeability to water keeps it the same
What percent of water and most solutes are reabsorbed
99%
what determines reabsorption across peritubular capillaries
Hydrostatic and colloid osmotic forces
What forces favors reabsorption
Plasma colloid osmotic pressure = 32mmhg
Hydrostatic pressure in interstitum = 6mmHg
What forces oppose reabsorption
Peritubular hydrostatic pressure = 13mmHg
Osmotic pressure of the renal interstitum = 15mmHg
What is the glomerular capillary net filtration forces
10mmHg
What is the peritubular capillary net re-absorptive forces
10mmHg
What determines filtration coefficient
Surface area of capillary
Permeability of capillary
What happens if we raise peritubular capillary pressure
Decrease reabsorption rate
What happens if peritubular capillary pressure decreases
Increase reabsorption
What happens if we increase resistance at the effernt arteriole
Incresae glomerular pressure
Decrease peritubular pressure
What is Natriuresis
Na excreted in urine
What is Diuresis
Water excretion to regulate BP
What secretes aldosterone
Zona glomerulosa cells of adrenal cortex
What does aldosterone do to kidneys
Regulates sodium reabsorption and potassium secretion
When is aldosterone relseased
Increased extracellular potassium
increased angiotensin II levels
What does ADH do
Increase water permability in the
Distal tubule
Collecting tubule
Collecting duct
What does ANP do
Inhibit renin
inhibit reabsorption of sodium potassium
When is ANP released
In congestive heart failure
What does angiotensin II do
Increase sodium and water reabsorption when BP is low
What does angiotensis II do to the efferent arterioles
Constricts them
What pH would make someone be in a state of acidosis
Below 7.4
What pH would make someone be in a state of alkalosis
above 7.4
What is the most powerful regulator of pH in the body
Kidneys
How long does it take for the kidneys to react to a change in pH
hours to days
What part of the tubule does Hydrogen secretion no occur
Thin ascending and thin descending limb of the loop of henle
Where does HCO3- reabsorption occur
Proximal tubules (80-90%) Thick ascending (10%)
Where is H+ secreted
Proximal tubule
Thick ascending limb
Early distal tubule
Where does Primary active transport of HCO3- occur
Late distal tubule and collecting tubule
What causes respiratory acidosis
increase Pco2
What causes metabolic acidosis
Fall in HCO3-
How does urine become acidic
Excess H+ in renal tubules causing complete reabsorption of HCO3-
What amino acids get used by the kidneys for Gluconeogenesis
Lactate
Glutamine
Glycerol
What is the osmolarity of the filtrate in the proximal tubule
300mOsm/L
When does Osmolarity start to increase
The descending segment of the loop of henle
What happens to osmolarity in the ascending portion of the loop of henle
It decreases
What happens to the osmolarity at the collecting tubules in the absence of ADH
Dilute urine
Low osmolarity
What happens to the osmolarity at the collecting tubules in the presence of ADH
Concentrated urine
high osmolarity
what are the basic requirments for forming a concentrated urine
High levels ADH
High osmolarity in medulla tissue
What creates hyperosmotic renal medullary interstitial fluid
Justamedullary nephrons
Vasa recta
What is the concurrent multiplier
Repetive reabsorption of sodium chloride in thick ascending loop and continued inflow of new sodium from the proximal tubule
what is the contribution of Urea to osmolarity of the renal interstitium
40-50%
What might be recycled many times between the medulla tissue and the filtrate in the renal tubule
Urea
What can be used to determine concentration of urine
Colour
Urine specific gravity
What happens if sodium content increases 2mEq/L above normal
Causes a desire to ingest fluid (threshold for drinking)
What can be done to control extracellular fluid if the kidneys can’t
Change BP
Change circulating hormones
Change sympathetic NS
What is it called when there is a rise in sodium that ocures with elevated BP
pressure natriuresis
What is it called when increased BP raises urinary volume
Pressure diuresis
What mechanism as long as it is working handles increases in fluid and salt intake
Pressure diuresis mechanism
a small Change in blood volume do what to cardiac output
Marked increase in cardiac output
A small change in cardiac output would do what to BP
Increase BP
a small change in BP does what to urine output
Increase urine output
What happens to urine output if there is a small change in blood volume
Increase urine output
What happens to a persons BP if they are salt sensitive and take in a small amount of salt
Marked increase in BP
What is the bodies more powerful controllers of sodium excretion
Angiotensis II
What drugs increase ADH secretion
Morphine
Nicotine
Cyclophosphamide
What drugs inhibit ADH
Alcohol
Clonidine
Haloperidol
What happens to pH when there is an increase of Extracellular postassium
Acidosis
What happens to pH when there is a decrease in potassium levels
Alkalosis
WHere is most of the potassium reabsorbed
Proximal tubule
What cells secrete potassium for excretion
Principal cells
What controls potassium secretions by the principal cells
Sodium-potassium ATPase pump
Electrochemical gradiant
Luminal membrane permebility
What cells reabsorb potassoium
Intercallated cells
Calcium in the blood is attached to what
Proteins
Where is most of the calcium in the kidneys reabsorbed
Proximal tubules