10/26/16 TEST #3 Columbo Renal physiology Flashcards
How many liters of fluid does the body have at any one time?
42 liters
How much urine can you excrete per day?
.5 L to 20 L
How many mL per day do you lose in insensible water loss from skin/respiratory tract?
700 mL
What is blood volume?
-Fluid in the plasma and contained in the RBCs
T/F
Vasodilation can increase the total blood volume
True
-But only to a certain point
What does substantial increased blood volume have to do with blood pressure?
Increased blood pressure
How many liters of fluid do you find in the blood?
5 liters
How do the kidneys help in regulating blood pressure?
-By controlling the urine volume
What are two things that kidneys help regulate other than blood pressure?
- Electrolyte balance
- Tonicity
Where is most of the body fluid found?
-Intracellular fluid (28 L)
What are(is) extracellular cations?
Na+
What are(is) extracellular anions?
Cl-
HCO3-
What are intracellular cations?
K+
Mg++
What are intracellular anions?
Protein
-PO4
T/F
In general waste products are highly filtered and poorly reabsorbed
True
What are 4 examples of metabolic waste?
- Urea
- Uric acid
- Creatinine
- Bilirubin
What are 4 examples of foreign substances that the kidneys excretes?
- Pesticides
- Food additives
- Toxins
- Drugs
What is an example of a nonvolatile acid that the kidneys can deal with?
-Lactic Acid
What is more important to retain, HCO3- or H+?
HCO3-
How can the kidneys produce new HCO3-?
-Metabolizing glutamine
T/F
Production of erythropoietin is not a renal function
False
It is a renal function
T/F
Gluconeogenesis is a renal function during a fasting state
True
What are the two basic parts of the kidney?
- Renal cortex
- Renal medulla
What specialized region do you find in the medulla of the kidney?
-Renal Pyramids
What are the renal pyramids composed of?
-Nephrons
What are nephrons?
-Basic filtration unit
How is each pyramid connected to the renal pelvis?
-Papilla
What are the three main processes of the kidney?
- Filtration
- Modification
- Excretion
Where do arteries and veins enter and leave the kidney?
-The hilum
What does the renal artery branch into?
Afferent arterioles
What do the afferent arterioles feed into?
-Glomerular capillaries
Where does filtration occur?
-Nephrons
Where do the nephrons receive their blood supply from?
-Glomerular capillaries
What do the glomerular capillaries feed into?
-Efferent arterioles
What do the efferent arterioles form?
Peritublar capillaries
What occurs in the capillary bed?
-Reabsorption/secretion
Which capillaries associated with the nephron has a higher hyrdrostatic pressure?
-Glomerular capillaries (60 mm Hg vs 13 mm Hg)
What is it called when the glomerulus is covered by epithelial cells?
Bowmans capsule
What passes out of the glomerulus into the bowmans capsule?
Plasma containing solutes
What are the two types of nephrons?
- Cortical
- Juxtamedullary
Which type of nephron penetrates deeply into the medulla?
-Juxtamedullary
Which type of nephron penetrates the medulla with only the loop of Henle?
Cortical
What type of blood supply is associated with the cortical nephrons?
-Peritubular capillaries
Where are the peritubular capillaries associated with the cortical nephron?
-Loop of Henle
What type of blood supply is associated with the loop of henle in the juxtamedullary nephrons?
- Vasa recta (specialized peritubular capillaries)
- Efferent arterioles
T/F
The vasa recta in the juxtamedullary nephrons allow highly concentrated urine and less water loss.
True
How much of the blood plasma presented to the glomerulus enters the proximal tubule via bowmans capsule?
20%
What is the formula for urinary excretion rate?
-(Filtration rate - reabsorption) + secretion
What is a normal total GFR per day?
180 L
Are water, sodium and glucose mostly filtered out for excretion or reabsorbed?
Reabsorbed
Is creatinine mostly filtered out for excretion or reabsorbed?
Filtered out
What is found on the glomerular capillary membrane that restricts the size and charge of molecules that are filtered?
-Filtration slits
How many membrane layers does the glomerular capillary bed have?
Three
What are the three membrane layers found in the glomerular capillary membrane?
- Endothelium
- Basement membrane
- Specialized epithelial cells (podocytes)
What unique feature does the endothelium layer of the glomerular capillary have?
-Fenestrae
What is the purpose of the basement membrane in the glomerular capillary?
-Fuse the endothelium and the podocyte layer
What is the formula for GFR?
GFR= Kf x Net filtration pressure
What does Kf measure?
-Surface area and hydraulic conductivity?
What is the net filtration pressure?
The sum of the colloid and hydrostatic pressures across the glomerular capillaries
What pressure is Pro-Filtration?
- Glomerular Hydrostatic Pressure (60 mmHg)
- Bowmans capsule colloid osmotic pressure (0 mmHg)
What pressures are Anti-Filtration?
- Bowmans Capsule Hydrostatic pressure (18 mmHg)
- Glomerular Colloid Osmotic Pressure (32 mm Hg)
What PNS system controls the diameter of the afferent and efferent arterioles?
Sympathetic
Does constriction or relaxation of the afferent arterioles increase pressure on the glomerulus?
Constriction
What does the increased pressure on the glomerulus do to blood?
Forces it out of Bowmans capsule
What does forcing blood out of the bowmans capsule do to the GFR?
-Decreases it
Minor constriction of the efferent arterioles does what to GFR?
-Increases it
Major constriction of efferent arterioles does what to GFR?
-Decreases GFR
Why does major constriction of efferent arterioles decrease GFR?
-Traps proteins in Bowmans capsule rasing colloid osmotic pressure
What are two systems/hormones that increase (raise) afferent resistance (constrict the afferent arterioles)?
- Sympathetic nervous system
- Catecholamines (norepinehprine)
What does Angiotensin II do to the efferent arterioles?
-Increase the resistance (constrict the efferent arteriole)
What does Angiotensin II do to GFR?
Prevents a decrease in GFR
What type of feedback links the sodium chloride concentration in the distal tubule with the constriction state of the afferent and efferent renal arterioles?
-Tubuloglomerular Feedback
Where do you find the macula densa?
Distal tubule
What does the macula densa do?
-Form the juxtaglomerular complex with the walls of both afferent and efferent arterioles
What does a decrease in NaCl concentration in the distal tubule indicate?
Decreased renal flow (GFR)
T/F
The macula densa initiates dilation in the afferent arterioles and causes an increased release of renin when there is a decrease of NaCl concentration
True
When the macula densa initiates dilation in the afferent arterioles will increase what hormones that subsequently cause constriction of the efferent arterioles?
-Angiotensin I and II
What differentiates glomerular filtrate in the proximal tubule from blood plasma?
The glomerular filtrate has no protein
If the body has high osmolarity (low body water) what type of urine will the kidney form?
-More concentrated urine
What are the different parts of the tubule system of the nephron?
- Proximal
- Loop of Henle
- Distal
- Collecting duct
How much of the filtrate is reabsorbed in the proximal tubule?
-80 %
How much filtrate is reabsorbed in the loop of henle?
-6 %
How much filtrate is reabsorbed in the the distal tubule?
9 %
T/F
The tubular reabsorption and secretion involve both active and passive transport
True
What does Co-transport do in the kidney?
-Brings glucose into the cell from tubule with Na+
What ion is excreted by counter-transport with Na+?
H+
What is the main function of the proximal tubule?
-Water reabsorption through passive diffusion linked to Na+ gradients
Where does water traverse the proximal tubules?
Tight Junctions
How much water and Na+ are reabsorbed in the proximal tubule?
65%
What do the cells bordering the proximal tubule have that allows a huge capacity for active transport?
- Brush border
- Mitochondria (tons)
Where is most of the glucose reabsorbed?
-Proximal end of proximal tubule
At the distal end of the proximal tubule what is mainly reabsorbed?
-Cl-
T/F
Na+ amounts decrease along the tubule but not the concentration
True
What two segments does the Loop of Henle have?
- Thin descending segment
- Thick ascending segment
What is the function of the thin descending segment?
- Highly permeable to water
- 20% water is reabsorbed here
What is the function of the thick ascending segment?
- Not permeable to water
- Reabsorbs Na+, Cl-, K+, and Bicarbonate
The transporters in the thick ascending segment only have a capacity to maintain how large of an osmolarity difference?
200 mOsm/L
T/F
The descending segment of the loop of henle has an equal mOsm/L as the interstitial fluid
True
What two features does the distal tubule contain?
- Macula densa
- Juxtaglomerular apparatus
Which part of the distal tubule is impermeable to water?
-Proximal part
What are the two distinct cell types of the distal half of the distal tubule?
- Principal cells
- Intercalated cells
What do principal cells do?
Reabsorb Na+ and water from the lumen and secrete K+ into it
What do intercalated cells do?
-Reabsorb K+ and HCO3- and secrete H+ into the tubule to regulate pH
What happens in the presence of ADH?
-Increase permeability causing further reabsorption making more concentrated urine
What happens in the lack of ADH?
-Dilute urine
Fine tuning water reabsorption occurs where?
-Distal tubule
T/F
The cortical collecting ducts have the same cells as the distal tubules
True
What are the two types of collecting ducts?
- Cortical collecting duct
- Medullary collecting duct
What does the medullary collecting duct cells do?
- Pump H+ into the lumen
- Permeable to urea
Where is urea passively reabsorbed?
- Proximal tubule
- Collecting ducts
Why is urea passively reabsorbed?
- To pull water back out of the tubual system
- Increase the concentration of urea into urine
Where does urea go back into the tubule system?
-Loop of Henle
Is blood flow fast or slow along the loop of henle?
-Slow
