Homework Quiz Question 1 Homework Quiz Question 2 You are sick and take an antibiotic. Describe the...
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Transcript of Homework Quiz Question 1 Homework Quiz Question 2 You are sick and take an antibiotic. Describe the...
Homework Quiz Question 1
Homework Quiz Question 2You are sick and take an antibiotic. Describe the pathway of the drug through the urinary
system, starting from the aorta to the toilet!
Passive transport. Substances move spontaneously down their concentration gradients, crossing a membrane with no expenditure of energy by the cell. The rate of diffusion can be greatly increased by transport proteins in the membrane.
Active transport. Some transport proteins act as pumps, moving substances across a membrane against their concentration gradients. Energy for this work is usually supplied by ATP.
Diffusion. Hydrophobicmolecules and (at a slow rate) very small uncharged polar molecules can diffuse through thelipid bilayer.
Facilitated diffusion. Many hydrophilic substances diffuse through membranes with the assistance of transport proteins,either channel or carrier proteins.
ATP
Three Functions of Urine Formation1. Filtration – movement of
fluids from the blood in the glomerulus to the Bowman’s capsule
2. Reabsorption – transfer of fluids from nephron into peritubular capillaries
3. Secretion – transfer of fluids from peritubular capillaries into nephron
Filtration.
Reabsorption.
Secretion.
Excretion.
Capillary
Excretorytubule
Filtrate
Urine
1
2
3
4
interstitial fluid
FiltrationWater and solutes flow from the
glomerulus into Bowman’s capsule due to high blood pressure flow65 mmHg vs. normall ~ 25 mmHg
Semi-permeable membraneRed blood cells, platelettes and
some blood proteins are too large to fit through the filtration slits and pores.
Filtration.
Reabsorption.
Secretion.
Excretion.
Capillary
Excretorytubule
Filtrate
Urine
1
2
3
4
Nutrient FlowSolute Glomerulus Bowman’s
Capsule?
water yes
NaCl yes
H+ ions yes
amino acids yes
glucose yes
plasma proteins no
red blood cells (erythrocytes)
no
platelets no
Reabsorption reclaims valuable substances from the filtrate and returns them to the body fluids.Water, salt and nutrientssaves us from having to
continuously replenish our body with fluid.
Filtration.
Reabsorption.
Secretion.
Excretion.
Capillary
Excretorytubule
Filtrate
Urine
1
2
3
4
Reabsorption
20% of fluid flowing into kidney is filtered into nephrons; however less than 1% of the fluid in the nephron is used to make urine.
A LOT OF REABSORPTION!
SecretionOther substances are
extracted from body fluids and added to the contents of the nephron toxins and excess ions
Filtration.
Reabsorption.
Secretion.
Excretion.
Capillary
Excretorytubule
Filtrate
Urine
1
2
3
4
Reabsorption
Secretion
protein transporters move nutrients into interstitial fluid and blood
kidney tissue will only reabsorb a certain level of nutrients – threshold level
Filtration.
Reabsorption.
Secretion.
Excretion.
Capillary
Excretorytubule
Filtrate
Urine
1
2
3
4
Diffusion. Hydrophobicmolecules and (at a slow rate) very small uncharged polar molecules can diffuse through thelipid bilayer.
Facilitated diffusion. Many hydrophilic substances diffuse through membranes with the assistance of transport proteins,either channel or carrier proteins.
ATP
protein transporters move wastes from blood to interstitial fluid to nephron
The Details…
1. Bowman’s CapsuleHigh pressure filterwater and dissolved solutes leave
glomerulus; enter Bowman’s capsule water
Na+
H+
Cl-
glucoseamino acidsvitaminsmineralsureauric acid
2. Proximal Tubule
Selective reabsorption of nutrients (need transporters)
Secretion of H+ and ammonia
pH determined by HCO3-
reabsorption and H+ secretion
H+
NH3
HCO3-, K+
Na+, Cl-
H2Oamino acidsglucosevitamins
3. Loop of Henle – Descending Limb
Nephron membrane only permeable to H2O (osmosis) and impermeable to salt
Reabsorption of waterAs fluids travel down the loop
of henle, the fluids within the tube become more concentrated.
H2O
4. Loop of Henle – Ascending Limb
only permeable to salt (need ionic transporters) and not permeable to water
Reabsorption of saltAs fluids travel up the loop of
henle the fluid is becoming less concentrated
NaCl
5. Distal Tubule
Selective reabsorption of nutrients (need transporters)
Secretion of H+, ammonia and K+
pH determined by HCO3-
reabsorption and H+ secretion
H+
NH3
K+
HCO3-
Na+, Cl-
H2O
6. Collecting DuctUrine formation by concentration of
nephron fluidAny urea and urine that is reabsorbed
is less than that was filtered into nephron
Why is some urea reabsorbed?Contributes to the formation of a
hypertonic interstitial fluidcauses water to be reabsorbedCONCENTRATING THE URINE
NaClureawater
Proximal tubule
Filtrate
H2OSalts (NaCl and others)HCO3
–
H+
UreaGlucose; amino acidsSome drugs
Key
Active transport
Passive transport
CORTEX
OUTERMEDULLA
INNERMEDULLA
Descending limbof loop ofHenle
Thick segmentof ascendinglimb
Thin segmentof ascendinglimb
Collectingduct
NaCl
NaCl
NaCl
Distal tubule
NaCl Nutrients
Urea
H2O
NaCl
H2OH2OHCO3
K+
H+ NH3
HCO3
K+ H+
H2O
1 4
32
3 5
H2O
H2O
H2O
H2O
H2O
H2O
H2O
NaCl
NaCl
NaCl
NaCl
NaCl
NaCl
NaCl
300
300 100
400
600
900
1200
700
400
200
100
Activetransport
Passivetransport
OUTERMEDULLA
INNERMEDULLA
CORTEX
H2O
Urea
H2O
Urea
H2O
Urea
H2O
H2O
H2O
H2O
1200
1200
900
600
400
300
600
400
300
Osmolarity of interstitial
fluid(mosm/L)
300
Osmolarity – concentration of solutes in a solution, the higher the Osmolarity, the more concentrated the solution, the better it is able to pull water towards it.
http://www.biologymad.com/resources/kidney.swf
Diabetes (Type II) Not enough insulin released from pancrease High levels of glucose in the blood
Why do you think that individuals with Type II Diabetes (untreated)
(a) Excrete a large amount of gluose in the urine?
(b) Excrete large amounts of urine?
Kidney Stonescrystallization of some
urine solutes
a 2 – 3 mm stone can obstruct flow to the ureter
Treatment:increased water
consumptionsurgery