What is the fluid osmolarity that the body maintains at homeostasis?
300 mOsm
What is the function of the Vasa Recta?
Counter-current exchanger that maintains osmolarity and delivers
blood to the cells in the area
What leaves/enters the blood as it descends the vasa recta?
Water leaves
Sodium Chloride enters
What leaves/ enters the blood as it ascends the vasa recta?
Sodium Chloride leaves
Water enters
What is Diuresis?
increased formation of urine by the kidneys
What two things are used as treatment for duiresis?
Diurectics: chemicals that enhance urine output (cranberry
juice, alcohol, caffeine) (dilute urine) Antidiuretics:
chemicals that decrease urine output (ADH) (concentrate urine)
What is included in osmotic diureitcs?
High glucose levels- carries water out w/ glucose
Alcohol- inhibits ADH
Caffeine- dilates afferent arteriole; inhibit sodium reabsorption
Lasix- inhibit Na+ symporters
What happens if ADH is not being secreted?
Diluted urine is formed by allowing the filtrate to continue into the
renal pelvis
Fill in the blank:
If you don't have a lot of ______, _________of urine is produced
ADH
A lot
What is the main function of ADH
Decrease urine output
Where is ADH produced?
What does it stimulate?
It is produced in the Posterior pituitary
Stimulates DCT and CD--> increases water reabsorption
What is the action course of ADH starting at dehydration?
Dehydration ( low H2O and high Na+) --> elevates blood osmolarity
--> stimulates hypothalamic osmoreceptors --> stimulates
posterior pituitary to release ADH --> stimulates distal convoluted
tubule and collecting duct --> increases water reabsorption
------> 1)reduces urine volume 2) increases ratio or Na : H2O in urine
What is the function of aquaporins
...
How many liters of blood are filtered a day?
200 L
What are the metabolic waste products?
** Urine contains metabolic wastes and unneeded substances
Urea, Uric acid, creatinine, ammonia
What transports urine from the bladder out of the body?
Urethra
What part of the kidney collects urine and empties into the pelvis?
Major Calyces
What are the two parts of the nephron?
1) Renal corpuscle- blood filtration
2)Renal tubule- processes filtrate into urine
What is the functional unit of the kidney that is responsible for
forming urine?
the Nephron
What are the two parts of the renal corpuscle?
Glomerulus & Glomerular capsule
Is the nephron fenestrated?
Yes, allows filtration
What are the different parts of the renal tubule?
1. Proximal convoluted tubule- reabsorbs water and solutes from
filtrate and secretes substances into it 2. Loop of Henle 3. Distal
convoluted tubule- more in secretion than reabsorption 4. Connecting tubules
What are the two types of nephrons?
1. Cortical nephron (85% of nephrons)
2. Juxtamedullary nephron (involved in the production of
concentrated urine)
What three processes are needed for urine formation?
Glomerular filtration, tubular reabsorption, and secretion
What is Net Filtration Pressure?
The pressure responsible for filtrate formation-- pushes everything
to the bladder
(10 mmHg)
What is blood hydrostatic pressure?
The pressure of blood flowing into the glomerulus through the
afferent arteriole
55 mmHG
What is colloid osmotic pressure?
The pressure of the pressure from the glomerulus on the blood
30 mmHg
What is the capsular pressure?
The pressure of the glomerus capsule
15 mmHg
What is the numerical value of the glomerular filtration rate?
125ml/min
What does it mean if the GFR is too low?
Everything is reabsorbed (too much)
What does it mean if GFR is too high?
Substances cannot be reabsorbed quick enough and are lost in the urine
What controls GFR?
Intrinsic control- renal autoregulation
Extrinsic control- neural and hormonal control (renin- angiotensin
system, ADH)
What are the two types of intrinsic control?
1. Myogenic: responds to changes in pressure in renal blood vessels
(contraction of afferent arteriole when BP increases)
2. Flow-dependent tubuloglomerular feeedback: senses changes in
the juxtaglomerular apparatus
What contains renin granules?
JG cells
Which cells within the glomerulus are chemoreptors?
Efferent arteriole and macula densa
What type of cells have phagocytic properties?
Mesanglial cells
What happens if GFR is too high?
Fluid is being filtered too quickly so there is not proper
concentration-> sodium levels increase -> macula densa cells
detect sodium chloride and tell JG cells to constrict and regulate
flow (vasoconstrict)
What nervous system is connected to the JGA for extrinsic control?
Sympathetic System
What happens to the JGA in a sympathetic response?
Norepinephrine-> epinephrine ->Vasocontrict -> less fluid
entering -> less filtration produced-> less peeing
Walk through the renin-angiotensin-aldosterone mechanism when there
is a drop in blood pressure
JG cells release renin -> (acts/cuts on angiotensinogen) ->
release angiotensin 1 -> ACE (angiotensin-converting enzyme::
secreted by type 1 alveolar cells) cuts angiotensin 1 to angiotensin 2
->angiotensin 2 vasoconstricts BP; tells adrenal cortex to produce
aldosterone for kidneys to retain sodium and water to elevate blood
pressure; reacts with the hypothalamus for thirst and drinking
What effect does angiotensin 2 have on urine?
constriction on efferent arteriole and in the long run causes less
volume and concentration is high
What are two important functions of the kidneys
1. maintain body fluid osmolarity at 300 mOsm
2. Regulate urine concentration and volume
What is the descending loop of henle impermeable to?
solutes
What is the descending loop of henle permeable to?
Water
What is the ascending loop of henle permeable to?
solutes
What is the ascending loop of henle impermeable to?
water
What is the function of the vasa recta?
Maintain osmotic gradient and deliver blood to the cells in the area
What is the countercurrent exchanger?
Vasa Recta
What leaves and what enters when going up the vasa recta?
Sodium chloride leaves and water enters
What leaves and what enters when going down the vasa recta?
sodium chloride enters and water leaves
True/ False:
The functional unit of the kidney is called a glomerulus
False
True/ False:
A glomerulus us fed by an efferent arteriole
False
True/ False:
A glomerulus us drained by an afferent arteriole
False
True/ False:
The vasa recta branches off an efferent arteriole
True
True/ False:
Average blood hydrostatic pressure is 55 mmHg
True
True/ False:
Average capsular pressure is 30 mmHg
False
GFR is the glomerular filtration rate of one kidney
False
True/ False:
Average colloid osmotic pressure is 15 mmHg
False
True/ False:
Net filtration pressure is -10 mmHg
False
False
True/ False:
If Kf is 20 ml.min, and NFP is NORMAL than GFR=125 ml/min
True
True/ False:
Aldosterone causes the kidneys to retain sodium
True
True/ False:
Autoregulation is the same as intrinsic control
True
True/ False:
Myogenic control is an intrinsic mechanism of control
False
True/ False:
Macula densa cells detract lo levels of NaCl
True
True/ False:
Mesanglial cells have phagocytic activity
True
True/ False:
Macula densa cells are chemoreceptors and osmoreceptors
True/ False:
Net filtration pressure is -10 mmHg
False
True/ False:
A potential vasoconstrictor produced by macula densa cells is cAMP
False
True/ False:
Renin is found in macula densa cells
False
True/ False:
Juxtaglomerular cells are innervated by parasympathetic fibers
False
True/ False:
Angiotensin 2 reduces blood pressure
False
What stimulates aquaporins into the principal cells?
ADH
What is facultative water reabsorption?
ADH dependent water reabsorption
What is the signal to produce concentrated urine
ADH
What muscle forms the internal sphincter of the bladder?
smooth muscle -> autonomic/ involuntary
What muscle forms the external sphincter of the bladder?
skeletal muscle -> voluntary
Explain the neural control of urination
Bladder fills and the stretch receptors detect the change and are activated
--> sends info to the nerves to activate smooth muscle and info
is sent to the cortex of brain to sacral 4 to external sphincter to
control when you let pee out.
What is the capacity of the urinary bladder?
600- 800 ml
What amount triggers micturition reflex?
200-300 ml
What keeps the urethra closed when urine is not being passed?
Sphincters
What/ and when is an adult kidney developed in a fetus?
the final metanephros are developed by the 5th week
Within a fetus, what does the cloaca develop into?
The rectum and anal canal
What month does the fetus's metanephric kindeys excrete urine?
the third month
Why do infants constantly have to pee?
they have small bladders and kidneys that cannot concentrate urine
What bacteria accounts for the majority of urinary tract infections?
What percentage?
E. coli
80%
Describe the process of dialysis
The blood in the body is high in toxins, so the blood is taken from
the body to the tank --> the tank removed the toxins within the
blood and is pumped back into the veins
What are the three layers of the bladder wall?
1. transitional epithelial mucosa
2. thick muscular layer
3. fibrous adentitia
What is the chemical composition of urine?
95% water
5% solutes
Name the nitrogenous wastes in urine
urea, uric acid, creatinine
Name some of the other solutes included in urine
sodium , potassium, phosphate, sulfate ions, calcium, bicarbonate
What is specific gravity dependent on?
solute concentration
What is renal clearance?
the volume of plasma that is cleared of a particular substance in a
given time
RC= GFR
What is the function of diuretics?
enhance the urine output/ dilute urine
What is the function of antidiuretics?
decrease urine output/ concentrate urine
What does alcohol inhibit?
ADH
What does caffeine inhibit?
sodium reabsorption