Kidney and Osmoregulation Quiz Flashcards
Draw and label the kidney and a nephron (and for each labeled structure, be able to explain its function).
From the Notes:
LOOK AT NOTES - The Kidney and Osmoregulation slide 5 and 6: https://docs.google.com/presentation/d/1TK-Rrh4o8rkYL2gXKE8UeJ9uUTxYupFZbjD6-UpPYRo/edit#slide=id.g1048861b947_0_18
KIDNEY:
- Renal artery brings “unclean” blood to each kidney (from body).
- In the cortex, this blood is filtered (in the glomerulus and bowman’s capsule - forming a fluid called “filtrate”), and essential nutrients are then reabsorbed back into it (in the proximal convoluted tubule).
- In the medulla, water is reabsorbed into the blood (loop of Henle and collecting duct).
- “Clean” blood flows out of the kidney and back to the body through the renal vein.
- Urine (urea, toxins, and excess water) collects in the renal pelvis and goes to the urinary bladder (where it is temporarily stored prior to excretion) through tubes called ureters.
NEPHRON:
- A capillary bed (glomerulus)
A capsule surrounding the capillary bed (Bowman’s capsule) - A tube (tubule) extending from Bowman’s capsule
(made up of the proximal convoluted tubule, loop of
Henle, and distal convoluted tubule) surrounded by a second capillary bed (peritubular capillary bed)
From the Worksheet:
Explain how the structure of the nephron and its associated blood vessels enable the kidney to carry out its functions.
a. Osmoregulation/excretion of nitrogenous waste/urea «is a function of the» kidney
b. Ultrafiltration in the glomerulus/smaller molecules filtered out in the glomerulus
OR
capillary walls/glomerulus permeable to smaller molecules
Reject ultrafiltration in the Bowman’s capsule.
c. Basement membrane/filtration slits/podocytes act as filter/prevent loss of «large» «proteins»/prevent loss of blood cells
d. High «blood» pressure in glomerulus due to larger afferent than efferent arteriole
e. «Selective» reabsorption of glucose/useful substances in proximal convoluted tubule
f. Microvilli/coiling/convolutions give large surface area
OR
pump proteins to reabsorb specific solutes «in proximal convoluted tubule»
g. Water reabsorbed in descending limb «of loop of Henle»
OR
descending limb permeable to water
h. Active transport/active pumping of sodium ions /Na* out of ascending limb «from filtrate to medulla»
i. Ascending limb is impermeable to water
j. Loop of Henle creates solute gradient /high solute concentration hypertonic conditions in medulla
k. Distal convoluted tubule adjusts pH/adjusts concentration of Na/K/H*
l. Water reabsorbed in collecting duct
m. Collecting duct permeability to water varies due to number of aquaporins/ ADH
n. Osmoregulation by varying the amount of water reabsorbed «in the collecting duct»
Explain how the structure of the glomerulus/ Bowman’s capsule facilitates its function (ultrafiltration).
Ultrafiltration is first process which begins removing wastes from blood. It is the non-specific filtration of blood under extremely high pressure (in Bowman’s capsule of the nephron). The structure of the glomerulus (capillary bed) and Bowman’s capsule (surrounding the glomerulus) are adapted to their function (ultrafiltration).
Structure
- How structure is adapted to its function
Wide afferent arteriole (a small branch of renal artery) and narrow efferent arteriole
- Because afferent (coming in) arteriole is much wider than efferent (going out) arteriole, this creates extremely high pressure glomerulus (which forces blood into capsule and facilitates filtration)
Highly branched (inside Bowman’s capsule)
- Increases surface area for filtration
Vessels contain fenestrations (small openings/ pores)
- Allow blood contents to pass through vessel membranes into Bowman’s capsule (open under high pressure)
Explain how the structure of the proximal convoluted tubule (PCT) facilitates its function (selective reabsorption).
- Filtrate flows inside the PCT within its lumen (the interior portion of the tube)
- Epithelial cells that line the wall of the PCT contain Microvilli, which project into the lumen (to increase surface area for reabsorption)
- The epithelial wall of the PCT is only ONE CELL THICK (decreases diffusion distance and increases diffusion rate) and cells contain mitochondria for active transport
- A network of capillaries (called the peritubular capillary bed) surrounds the PCT for reabsorption
Explain the role of the kidney in osmoregulation.
__Note that__ there are MANY different ways IB likes to ask this question. Here the other types of ways you will see this question asked:
- Explain how water balance is maintained in the body.
- Explain how water balance is restored when the body is dehydrated.
- Explain how the different parts of the kidney and kidney processes balance water and solute concentrations.
- Explain how blood solute concentrations are kept within narrow limits in the human body.
__Note that__ ADH is pretty much ALWAYS 3-4 marks on the mark schemes of these
questions too - and these are the BIG questions - like 8 or so marks each!
From the Notes:
- Renal artery brings “unclean” blood to each kidney (from body).
- In the cortex, this blood is filtered (in the glomerulus and bowman’s capsule - forming a fluid called “filtrate”), and essential nutrients are then reabsorbed back into it (in the proximal convoluted tubule).
- In the medulla, water is reabsorbed into the blood (loop of Henle and collecting duct).
- “Clean” blood flows out of the kidney and back to the body through the renal vein.
- Urine (urea, toxins, and excess water) collects in the renal pelvis and goes to the urinary bladder (where it is temporarily stored prior to excretion) through tubes called ureters.
From the Worksheet:
Explain how blood solute concentrations are kept within narrow limits in the human body.
[7 marks]
a. solute concentration of blood monitored by the brain/hypothalamus
b. pituitary gland secretes ADH
c. ADH secreted when solute concentration/osmolarity is too high/a person is dehydrated/OWTTE
d. collecting duct more permeable to water
e. «more» aquaporins/opens aquaporins «in the plasma membrane of collecting duct cells»
f. «more» water reabsorbed «into the medulla»
g. medulla is hypertonic /hyperosmotic «so water can be reabsorbed from filtrate»
h. small volume of urine/concentrated urine produced «with ADH»
i. no /little less ADH secreted if «blood» solute concentration is too low
j. collecting duct less permeable to water less water reabsorbed/large volume of urine produced/dilute urine produced «with low /no ADH»
k. insulin causes blood glucose «concentration» to be reduced
l. glucose stored as glycogen in the liver
m. glucagon causes blood glucose «concentration» to be increased
n. negative feedback
ADH (antidiuretic hormone) is a peptide hormone that is produced in the hypothalamus. Explain its action in the human body.
[8 marks]
a. ADH plays a role in osmoregulation/regulating blood solute concentration
b. acts on the collecting ducts of the kidney
c. acts in «late» distal convoluted tubule
d. hypothalamus detects plasma/blood osmolarity / solute concentration
e. if plasma/blood is too concentrated hypertonic, «posterior» pituitary releases ADH
f. ADH stimulates insertion of aquaporins /water channels / increases permeability of collecting duct
g. water moves «through aquaporins» by osmosis into the medulla/blood
h. urine becomes more concentrated/smaller volume
i. negative feedback occurs OWTTE for negative feedback acceptable.
j. if blood is hypotonic no ADH is released
k. water is not reabsorbed from the collecting ducts/permeability of the collecting duct decreases
l. urine becomes more dilute less concentrated / higher volume
Compare (similarities and differences) osmoregulators and osmoconformers.
From the Notes:
Osmoregulators are animals whose internal tissues maintain different solute concentrations than their environment (birds, mammals, humans, freshwater fish)
* Osmoregulation requires more energy to maintain, but it ensures that internal solute concentrations are strictly controlled (they vary less)
Osmoconformers are animals whose internal tissues maintain the same solute concentrations as their environment (they are iso-osmotic to their surroundings).
* Osmoconforming requires less energy to maintain internal osmotic conditions, and minimizes water movement in and out of cells, but it is more affected by the environment (and organisms are HIGHLY restricted to where they can live).
* Ex: Sharks, squid, jellyfish, crabs, mussels etc.
From the Worksheet:
a. concentration constant inside osmoregulators versus variable inside osmoconformers
b. internal solute concentration can differ from the external environment in osmoregulators versus same/ equal in osmoconformers
OR
osmoregulators are independent of the external environment in solute concentration versus osmoconformers are tied to it
c. birds/mammals/humans/freshwater fish are osmoregulators versus starfish/mussels/crabs/jellyfish/sea squirts/squid/sharks are osmoconformers
Compare (similarities and differences) the composition of blood in the renal artery and renal vein (and explain WHY the concentrations are higher, lower, or the same).
Urea
- Higher in the renal artery
- Lower in the renal vein
- Urea removed through ultrafiltration and excretion
Oxygen
- Higher in the renal artery
- Lower in the renal vein
- Oxygen used to make ATP for active transport of essential substances (glucose, amino acids) back into blood
Carbon Dioxide
- Lower in the renal artery
- Higher in the renal vein
- Waste product of cell respiration in kidney cells as make ATP for active reabsorption
Glucose
- Higher in the renal artery
- A LITTLE Lower in the renal vein
- Used in cellular respiration in kidney cells to make ATP (but close to the same as all reabsorbed in PCT)
Sodium and Chloride Ions
- Higher in the renal artery
- Lower in the renal vein
- Pumped into medulla (or excess excreted) and diluted if ADH secreted
Water
- Higher in the renal artery
- Lower in the renal vein
- Used to dilute urea (more reabsorbed if ADH secreted)
Drugs/ Toxins
- Higher in the renal artery
- Lower in the renal vein
- Excreted in urine
Blood cells, proteins, and platelets
- Identical in the renal artery
- Identical in the renal vein
- Too large to pass through basement membrane during ultrafiltration
Outline an adaptation of the kidney to maintain osmolarity in desert animals.
A longer loop of Henle is an adaptation for water conservation in animals that live in arid (desert) environments
Example: Kangaroo rats
- Almost all water comes from food they eat (as water is so scarce) and they are nocturnal (to preserve water as well)
- Have VERY LONG loops of Henle (more surface area so more water is reabsorbed rather than excreted in urine).
Outline the use of ammonia, urea, and uric acid in different types of animals (know which types of animals excrete which type of nitrogenous waste and WHY).
Ammonia
- Produced by: Fish (and most aquatic animals)
- Disadvantages: VERY toxic (must be removed from body quickly and diluted with LARGE amounts of water)
- Why it’s used: Fish live in water so have unlimited supply of water to dilute ammonia and it does not require much energy to make
Urea
- Produced by: Mammals, amphibians, sharks
- Disadvantages: Requires some water for dilution and requires more energy to produce than ammonia
- Why it’s used: Urea only toxic at higher levels; kidneys prevent excessive build up. Requires some water for dilution but not as much as ammonia (mammals have less access to water than fish); can be stored (short-term) in bladder
Uric Acid
- Produced by: Birds, many reptiles, and insects
- Disadvantages: Requires A LOT of energy to produce
- Why it’s used: Insoluble in aqueous solutions (so CAN be stored with reptile and bird embryos in developing eggs - no toxicity of ammonia); requires little to no water for dilution (excreted in concentrated form) and removal from body, so do not need to find water as frequently
Explain how insects excrete nitrogenous wastes.
__Understand that__ the Malpighian tubule system in insects and the kidney carry out osmoregulation and removal of nitrogenous waste.
In insects, Malpighian tubules remove wastes from the hemolymph (fluid analogous to blood), and they CONNECT to the digestive system.
- Malpighian tubules branch off intestinal tract in insects. At the far ends, they filter salts and ammonia (active transport), and water out of the hemolymph (these then pass INTO the gut)
- Salts, solutes, and water are reabsorbed back into the
hemolymph in the hindgut and ammonia (converted to uric acid) forms a precipitate/ solid/ paste and combines with undigested food and is excreted with feces via the rectum/ anus.
Outline the use of urinalysis in diagnosis and the detection of drugs (specifically, refer to glucose, proteins, and blood cells being present in a urine sample - what they indicate, and where damage or infection is possible).
When you go to the doctor and you have to provide a urine sample (for urinalysis), your doctor is looking for:
- Blood cells: Urine should not have blood cells in it (they are too large to fit through the fenestrations in the glomerulus). Blood cells indicate infection, kidney malfunction, and/ or bleeding in the renal tubes.
- Glucose: Urine should not have glucose in it (it should all be reabsorbed in the PCT). Excess glucose that is unable to be reabsorbed by PCT indicates diabetes.
- Proteins: Urine should not have proteins in it (too large to pass through fenestrations in the glomerulus). Proteins indicate disease, hormonal conditions, or even pregnancy
- Drugs: Urine should not have drugs in it (not naturally found in body)
Discuss the treatment options for kidney failure.
Hemodialysis: filtering blood through an external apparatus called a dialyzer.
- Dialyzer contains semi-permeable membranes (restricting passage of larger substances) and dialysis fluids called dialysates (to remove wastes and maintain concentration gradients).
- Takes up to 4 hours and can be done up to 3 times per week (short-term solution though; only a few years)
Kidney transplant: long-term treatment
- Requires close genetic match (and Immunosuppressant drugs)
- Kidney grafted into abdomen and connected to recipient’s vessels (often from family, as can live with only one)
