The Kindeys Flashcards
Name the 10 parts of the kidneys
1) Adrenal cortex
2) Adrenal medulla
3) Renal pelvis
4) Renal medulla
5) Renal Pyramid
6) Renal Artery
7) Renal Vein
8) Renal Capsule
9) Nephron
10) Ureter
Name the 7 parts of the nephron (in the order)
1) Glomerulus
2) Bowman’s capsule
3) Proximal convoluted tubule (PCT)
4) Loop of Henle
5) Distal convoluted tubule (DCT)
6) Collecting duct
7) Ureter
What is excretion
The removal of metabolic waste from the body
Name 4 excretory organs
1) Kidney
2) Lungs
3) Skin
4) Leaf
What substances are excreted from the kidney
(What structures do they involve and why is it important)
Substances excreted: Urea, excess water, excess minerals (salt)
Structures involved: nephrons, bladder
Importance: removal of toxic substances
What substances are excreted from the lungs
(What structures to they involve and why is it important)
Substances excreted: CO2 and water vapour
Structures involved: alveoli
Importance: to allow oxygen to enter the blood
What substances are excreted from the skin
(What structures to they involve and why is it important)
Substances excreted: Sweat (salt water)
Structures involved: Sweat glands
Importance: homeostasis, thermoregulation
What substances are excreted from the leaf
(What structures to they involve and why is it important)
Substances excreted: O2, CO2, water vapour
Structures involved: stomata, guard cells, xylem
Importance: human respiration
How would you describe the cortex
Anything in the upper section
How would you describe the medulla
Anything that spans downwards
What are the Malpighian bodies
A collective name for the Glomerulus and the Bowman’s capsule
What structures can you find in the kidney’s cortex
1) Proximal convoluted tubule
2) (some of the) Distal convoluted tubule
3) Malpighian bodies
What structures can you find in the kidney medulla
1) Loop of Henle
2) (some of the) Distal convoluted tubule
3) Collecting duct
What are the functions of the kidney
1) Excretion of waste products (main function)
2) regulate waste products, ions and water in the bloodstream
What is the first stage in excretion
Ultrafiltration
What is ultrafiltration based on
Size
What are the two blood vessels involved in ultrafiltration
1) Afferent arteriole vessel
2) Efferent arteriole vessel
Describe the characteristics of the afferent arteriole vessel
- wider
- bring blood into the glomerulus
- it is at a high pressure
Describe the characteristics of the efferent arteriole vessel
-narrower (so blood in the glomerulus is under high pressure)
-carries blood away from the glomerulus
-high pressure but lower than afferent arteriole
Explain why we need a build up of pressure between the afferent and efferent arterioles (bottleneck effect)
It allows for a larger volume of blood to be taken in so more blood can be filtered. The high pressure forces liquid and small molecules in the blood into the Bowman’s capsule.
What is the pressure value that allows for filtration to occur
> 6.7kPa
What are the three layers that the liquid and small molecules have to pass through to get into the Bowman’s capsule
1) Endothelium capillary: small gaps/pores that allow for small molecules to pass through
2) Basement membrane: membrane made of collagen fibres and glycoproteins that stops things (blood cells, proteins etc) leaving the glomerulus
3) Epithelium of the Bowman’s capsule (podocytes): have extensions (pedicels) ensuring gaps between the cells for fluid from glomerulus into the lumen of Bowman’s capsule
At the end of ultrafiltration what is the filtered substances called
Filtrate
What things are filtered from the Glomerulus into the Bowman’s capsule
- Water
- Amino acids
- Glucose
- Urea
- Inorganic ions
How small do these molecules have to be to be filtered out
Have to have a relative molecular mass (RMM) of 69,000
What are left in the capillary
-blood cells
-proteins
Why does water potential in the capillaries become negative? How is this helpful
Because water is moved into the capillaries. helps with reabsorption of water
What is selective reabsorption
Reabsorbing useful molecules back into the blood
What part(s) of the nephron is involved in selective reabsorption
PCT (mainly) but also the DCT
What molecules do we reabsorb back into the blood
- Glucose= used for respiration
- Water
- Amino acids
- inorganic ions
What molecule do we never reabsorb back into the blood and why
UREA!!
- as it is toxic
What on the PCT provides a large SA
The epithelium wall having microvilli
Describe the mechanism of selective reabsorption
1) sodium ions are actively pumped out of the cell lining the tubules
2) concentration of sodium ions in the cell cytoplasm decreases, creating a concentration gradient
3) sodium ions diffuse into the cell through cotransport proteins which also carry glucose or amino acids at the same time
4) water moves into the cell by osmosis (since there is a decrease in the water potential with all the solutes moving in)
5) glucose/amino acids diffuse into the blood
Summarise the roles of the PCT and DCT that are the same and the role that is different
Similarities:
-sodium ions actively pumped out from tubule into the blood
-water follows passively by osmosis
Difference:
-PCT= glucose co-transported with sodium ions (100% reabsorbed)
-DCT= ammonia actively secreted into tubule from blood
What is the maximum water potential
Zero (water)
How is water potential affected (in general)
When water moves in (water potential is increased, less negative) and when water moves out (water potential is decreased, more negative)
Define the term osmolality
The measure of solute concentration
Units: mosmkg-1=miliosmole per kilogram
What are the two parts of the loop of Henle
- ascending limb (AL)
- descending limb (DL)
Describe the first part of the loop of Henle
DL (near PCT):
-narrow
-thin walls
-highly permeable to water
Describe the second part of the loop of Henle
AL:
-wider
-thick walls
-impermeable to water
Why is it important to make sure that water potential is regulated
-so too much water isn’t kept which may cause it to move into cells (cell lysis) or not enough water being around the cell causing water to move out of cells (cell plasmolysis)
How is water gained
-Food
-Drink
-Metabolism
How is water lost
-urine
-sweat
-exhaled air (water vapour)
-faeces
What is a receptor
Something that detects a change from the stimulus
What is the receptor in osmoregulation
Osmoreceptor cells in the hypothalamus
How do the osmoreceptor cells detect this change
They are sensitive to changes in the water potential of tissue fluids
What are effectors
A muscle or gland that coordinates a response based on the detected stimulus
What are the effectors in osmoregulation
kidney’s collecting ducts
What is the hormone used in osmoregulation
ADH (anti diuretic hormone)
Where is ADH produced
Hypothalamus
Where is ADH secreted from
Posterior Pituitary Gland
How does ADH leave the posterior pituitary gland once it has been secreted
Via exocytosis
What is ADH stored in, in the posterior pituitary gland
Vesicles
Describe nephron osmoregulation that occurs in the loop of Henle
1) Na+ moves actively out from the AL into the interstitial space then into the DL
2) this movement of Na+ into the interstitial space decreases the water potential
3) water moves out of the DL into the interstitial space
4) but Na+ is still moving into he DL so there is a decrease in water potential, with the concentration of solute increasing as you go down
5)as there is a high concentration of Na+, it moves out of the AL into the interstitial space, decreasing the water potential so water moves out the collecting duct into the interstitial space
6) there is now a high water potential moving up the AL so water moves out into the blood capillaries
7) there is also an increase in concentration of Na+ and a decrease in water potential allowing for a constant concentration gradient in the collecting duct, and the further down you go in the interstitial space (in the medulla) the higher the solute concentration
The PCT is ….. permeable to water
The DCT is …… to water
The collecting duct has ….. permeability
Highly
Highly impermeable
Variable
What happens when you have a longer loop of Henle
More water can be reabsorbed from the filtrate
What animals need a longer loop of Henle and why
Desert animals: camels, fennec fox etc
-because a long AL means more ions are actively pumped out which creates a really low potential so more water moves out the nephron and the collecting duct into the capillaries
What does ADH do
Increases/ deceases water permeability
Describe the process that takes place when a person is dehydrated (low water potential)
1)There is a low water potential in the blood detected by the osmorecpotors in the hypothalamus. This releases more ADH from the posterior pituitary gland
2) The ADH travels through the blood and binds to the complementary membrane bound receptors. This activates the phosphorylase enzyme
3) This phosphorylase enzyme causes the vesicle containing aquaporins to move to the cell membrane
4) This inserts more aquaporins into the cell membrane
5) making the cell walls of the collecting duct more permeable and creating a channel for water to flow in by osmosis (high to low concentration)
6) water enters the blood stream increasing water potential
7) Brining the water potential of the blood back to ‘normal’
Describe the process that happens when a person is hydrated (high water potential)
1) There is a high water potential in the blood, which is detected but the osmoreceptor cells in the hypothalamus. This releases less ADH from the posterior pituitary gland
2) Less ADH travels through the blood and binds to the complementary membrane bound receptor. This doesn’t activate the phosphorylase enzyme
3) So the aquaporins become detached and move into the cytoplasm
4) The walls of the collecting duct become less permeable so water cannot move in via osmosis
5) The water potential of the blood reduces as there is less water reabsorbed
6) Greater volumes of urine produced
What are the reasons for kidney failure
- damaged or destroyed by infection
- genetics conditions
- damaged due to an accident
- caused by other conditions-> diabetes, heart disease, hypertension
Why is kidney failure serious
-causes toxins like urea to build up in the body
-affects water and mineral ion balance which damages cells by osmosis
-leads to rapid death (in some cases)
What two ways do we assess kidney function
1) measuring the glomerular filtration rate (GFR)
-> see how much fluid passes into the nephrons each minute
-> normal reading is 90-120cm3min-1
2)urine testing- to look for the presence of proteins
What are the two types of treatments for kidney failure
1) Dialysis
2) Transplants
What are the two types of dialysis
1) Haemodialysis (Renal Dialysis)
2) Peritoneal Dialysis
Describe haemodialysis
-contains a bag with the correct concentrations to allow for the blood to have what it needs in the right amounts
dialysis fluid contains:
-same concentration of glucose as the blood-so there is no net movement of glucose
-normal plasma levels of water and mineral ions- any excess ions and water are removed from the blood by diffusion
-no urea- steep concentration gradient to remove urea from blood
Describe the direction of the dialysis flow compared to the blood flow in haemodialysis
Countercurrent (opposite ways)
This is to ensure that there is a concentration gradient being maintained
Describe peritoneal dialysis
-bloods stays in the body and the persons own abdominal membrane is used as the dialysis membrane
-surgeon inputs permanent tube into the abdomen
-dialysis solution is poured through the tube and fills the space between abdominal wall and organs
-solution is drained every couple of hours
Describe a kidney transplant
A new kidney is implanted into a patient’s body to replace damaged kidney.
-> has to be from someone with the same blood and tissue type
Advantages of Haemodialysis
-not as invasive
-gets the correct concentration into the blood
Disadvantages of haemodialysis
-time consuming, can last very long and includes multiple visits a week
-very controlled low protein, low salt diet
Advantages of Peritoneal dialysis
-gets the correct concentration of molecules into the blood
-can be carried out anywhere
Disadvantage of peritoneal dialysis
-risk of infection from tube
-time consuming
-invasive technique
Advantages of kidney transplant
- freedom from time consuming dialysis
- feel physically fitter
- improved quality of life
- improved self image
Disadvantages of kidney transplant
-risk of rejection
-need to take immunosupressant drugs
-need from major surgery under general anaesthetic
-regular checks for signs of rejection
-side effects of immunosuppressant drugs-more susceptibility to infection
What can urine be tested for
-anabolic steroids (sporting drugs)
-recreational drugs (cocaine, ecstasy, cannabis)
-pregnancy testing
-alcohol levels in drivers
-glucose (for diabetes)
Describe pregnancy testing using urine
1)urine is poured onto a test stick
2) hCG (a hormone only found in pregnant women) binds to mobile antibodies attached to blue beads
3) the mobile antibodies moves down the test stick
4) if hCG is present, it binds to fixed (immobilised) antibodies which holds the bead in place
5) a blue line forms
6) there is also a control zone to show the test is working (second blue line)-> the mobile antibodies with no hCG attached bind to another fixed site
7) if no hCG is present the mobile antibodies continues to move to the end and no blue line forms
What are anabolic steroids and why are they banned
-used to build muscle mass
-banned because they cause unfair competition between athletes and because of their dangerous side effects (liver damage)
What is the test for anabolic steroids called
-GC/MS (gas chromatography and mass spectrometry)
Describe the urine test for anabolic steroids(GC/MS)
1)urine sample is vaporised (turned into a gas)
2)passes through a column containing a polymer
3)different substances move through the column at different speeds, so substances in the urine sample separate out
4) once they have separated out the mass spectrometer converts them out into ions depending on their mass and charge
5)results are then analysed by a computer and compared to tell which substances were in the urine
Describe the urine test of recreational drugs
-usually test strips
-certain amounts of the drug present will cause a colour change (meaning a positive result)
-sample of urine is then sent for further testing to confirm which drugs have been used. This second test uses GC/MS
What is the interstitial space
The medulla
What processes takes place in peritoneal dialysis
Active transport
Diffusion
What process takes place in haemodialysis
Simple diffusion
