KIDNEY AND DISEASES Flashcards
by what process do plants uptake nitrates
facilitated diffusion
do plants excrete nitrogen-containing molecules
no they do not
what happens to excess amino acids in animals
they are deaminated in the liver and converted to other molecules which are excreted
do animals excrete nitrogen-containing molecules
no
can excess amino acids that are not used for protein synthesis be stored by the body
no
deamination
the removal of the amino group from amino acids to leave pyruvate and ammonia
what happens to the ammonia formed from deamination
converted to urea in the liver
what happens to the pyruvic acid left after deamination
used in respiration as a source of energy or it is converted to fat and stored
what nitrogenous waste do aquatic animals excrete
ammonia
is ammonia soluble
yes
what happens to ammonia in freshwater fish
it is lost as ammonium ions across the epithelium of the gills.
what happens to ammonia in soft-bodied vertebrates
diffuses across the whole body surface of the fish into surrounding waters
is uric acid soluble in water
no
is uric acid toxic
no
organisms that release uric acid as their major nitrogenous waste
land snails, insects, birds and some reptiles
in what state is uric acid released
as a precipitate
organisms that excrete urea as their major nitrogenous waste
most terrestrial animals
order these in terms of least toxic to most toxic
ammonia
uric acid
urea
uric acid
urea
ammonia
why is excreting urea more advantageous to land animals than excreting ammonia
it enables them to lose less water while discarding their nitrogenous waste
homeostasis
the maintenance of a relatively constant environment for the cells within the body
things in the body that can be controlled by homeostasis
temperature
ph
salt levels
glucose levels
importance of homeostasis
helps obtain optimal conditions for cellular reactions
gives organisms independence from the external environment while still existing within it
homeostasis is maintained through a combination of ………….. and …………… mechanisms, often by ……………..
nervous and hormonal
negative feedback
negative feedback
the term to describe the fact that when a factor moves away from the ideal/norm, a set of processes move it back towards normal again
hormones
molecules that are released by the endocrine glands directly into the blood that travels to a target organ to produce an effect
endocrine glands
the ductless gland that secretes hormones directly into the blood
target cells/tissues
cells that have receptors that are embedded in the plasma membrane that are complementary in shape to specific hormone molecules
exocrine gland
a gland that secretes substances into a duct
functions of a kidney
filters the blood to remove nitrogenous metabolic waste to produce urine
osmoregulation
osmoregulation
the control of water and solute composition of bodily fluids
where do the kidneys receive blood from and where is the blood returned to
the renal artery and it is returned via the vena cava to the renal vein
what does the renal cortex contain
the glomeruli(bowman’s capsule)
what does the renal medulla contain
the loop of Henle and the collecting ducts
the function of the renal pelvis
empties urine into the ureter
the function of the vasa recta
blood in the vasa recta delivers nutrients and oxygen to the cells of the nephrons
ultrafiltration
the filtration of small molecules from blood plasma to the lumen of the bowman’s capsule under high pressure
location of ultrafiltration
the bowman’s capsule
the high filtration pressure of the glomerulus is caused by
the high hydrostatic pressure in the renal artery
the difference in diameter of the afferent and efferent arterioles
which is narrower, the afferent or the efferent arteriole
the efferent arteriole
nephron
an individual filtering unit
what structures do the cortex contain
Proximal convoluted tubule
distal convoluted tubule
the glomerulus
bowman’s capsule
what structures do the medulla contain
the henle loop
collecting duct
capillaries
what do the walls of the capillary(endothelium) of the glomerulus contain
pores known as fenestrae
what is the basement membrane of the glomerulus made up of
extra-cellular layer of proteins, mainly collagen and glycoproteins
function of the basement membrane
it is a molecular sieve that forms the selective barrier between the blood and the bowman’s capsule
what is the wall of the bowman’s capsule made up of
squamous epithelial cells known as podocytes
podocytes have large extensions called ………
pedicels
where can pedicels be found, and what are the large gaps between them called
they are wrapped around the capillary and the gaps are called filtration slits
explain how the structure of the glomerulus and the renal capsule allows for ultrafiltration to occur
the blood entering the glomerulus is separated from the space inside the the bowman’s capsule by two layers and a basement membrane
can molecules in the blood with RMM less than 30000 cross the basement membrane
yes
can molecules in the blood with RMM more than 30000 cross the basement membrane
no
what are the molecules in the PCT after ultrafiltration called
the glomerular filtrate
name four components of the glomerular filtrate
water
glucose
amino acids
urea
vitamins
sodium ions…(salts)
why causes glomerular filtration to occur?
explain
water potential
the net effect of hydrostatic pressure in the capillary and low solute potential in the bowman’s capsule causes water to move out of the blood
where does selective reabsorption occur
the PCT(proximal convoluted tubule)
what is selective reabsorption
the reabsorption of all the glucose and amino acids and most of the water and mineral ions from the glomerular filtrate back into the blood
adaptations of the PCT that allows for selective reabsorption
many mitochondria for the active transport of glucose and mineral ions
they have microvilli, which provides a large surface area for co-transport
they have a close association with the capillary, this provides a short diffusion pathway
tight junctions between cells. this prevents molecules from diffusing between cells, or from the cell back into the filtrate
is selective reabsorption a passive or an active process
it could be either, but most of it uses membrane pumps(passive)
describe the process of selective reabsorption using bullet points
Co-transport of glucose with Na+ via facilitated diffusion into the cell
diffusion through cell
Glucose diffuses through a channel protein into the capillary of and Na+ are taken actively
water moves freely out of the filtrate into the blood by osmosis because ions and glucose leave the filtrate, so it’s solute potential decreases
urea is reabsorbed by diffusion in the PCT as there is a higher concentration of it in the filtrate than in the blood
creatinine and uric acid are actively secreted into the lumen of the PCT
percentage of water reabsorbed in selective reabsorption
90
percentage of urea reabsorbed in selective reabsorption
50
describe the Na+/glucose co-transport in bullet points
sodium ions pumped out of the cell ad potassium ions pumped in by active transport
there is now a higher concentration of Na+ in the filtrate than in the cell, so Na+ moves into the cell via facilitated diffusion
channel protein only allows Na+ to diffuse if it is coupled with glucose
so Na+ brings glucose back into the cells/tissues
a channel protein allows glucose to pass into the blood down it’s concentration gradient via facilitated diffusion.
this is called secondary active transport
FUNCTION OF THE LOOP OF HENLE
to conserve water
which limb of the loop of Henle is
permeable to water
not permeable to water
descending limb
ascending limb
describe the events that take place in the loop of Henle
Na+ and Cl- are actively pumped out of the ascending limb, causing the solute potential in the medulla tissue fluid to increase
water moves out of the descending limb by osmosis. the water does not dilute the solute potential of the medulla because it is transported directly to the blood capillaries of the nearby vasa recta, so it is reabsorbed into the blood
the fluid in the descending limb becomes more concentrated as it moves down due to the water loss
the filtrate in the descending limb and the tissue fluid of the medulla are most concentrated at the tip of the loop of henle
what is the relationship between the length of the loop of henle and the environment of the organism
terrestrial organisms that live in areas where there is limited amounts of water have longer loop of henle as they need to reabsorb as much water as possible
aquatic animals, living in areas where water is abundant have a short loop of henle, as they do not need to reabsorb as much water from the glomerular filtrate
humans have a moderate length of loop of henle.
the sites of osmoregulation
the DCT
the collecting duct
the permeability of the DCT and the collecting duct is regulated by proteins known as ?
hormones
osmoregulation
homeostatic control of water and solute concentration of the blood
osmoregulation is an example of …………. feedback
negative
what is the name of the hormone released during osmoregulation
ADH( Antidiuretic hormone)
describe the events that occur when there is a decrease in water potential of the blood
osmoreceptors in the hypothalamus detect the decrease in water potential of the blood flowing through it
the posterior lobe of the pituitary gland releases ADH
cells of the collecting duct and of the kidney nephron (aka target cells) become more permeable to water, due to aquaporins fusing with the cell membrane
more water is reabsorbed from the collecting ducts into the blood.
describe the events that occur when there is an increase in water potential of the blood plasma
osmoreceptors in the hypothalamus detect the increase
posterior lobe of the pituitary gland stops the release of ADH
target cells become less permeable to water, due to aquaporins moving out of the membrane
less water reabsorbed from the collecting duct into the blood
can ADH pass through membranes
no
so it binds to receptors on the membranes
what happens after ADH binds to receptors on the membranes
secondary messengers travel through the cytoplasm to cause vesicles containing aquaporins to fuse with membrane
why are tea and coffee diuretics
they contain caffeine which increases the production of urine, thereby making them diuretics
what happens when the kidney fails
there is a build up of urea to toxic levels
excess water in bodily fluids causes reactants for chemical reactions to become diluted
the main causes of kidney diseases
high blood pressure
infection
loss of blood pressure due to dehydration or blood loss
Auto-immune disease
diabetes
Crushing injuries that might affect the kidney structure
why are treatments required when both kidneys fail
to reduce the concentration of toxic wastes
to regulate the volume of bodily fluids, therefore the solute potential
name treatments for kidney failure
drugs
dialysis
kidney transplants
low protein diets to reduce urea formation
state two drugs to reduce blood pressure and state what they do
calcium channel blockers: they dilate blood vessels, thereby reducing the pressure of blood flowing through them
beta blockers: they reduce the effect of adrenaline which increases blood pressure
potassium and calcium ion concentrations in body fluids are usually regulated by ……….
reabsorption in the small intestine and selective reabsorption in the PCTs
what does high potassium concentrations in the blood lead to
heart arrhythmias(irregular heart rhythms)
treatment for heart arrhythmias
the use of glucose and insulin together with intravenous calcium to stabilise the heart muscle membranes
which diseases can be caused by high calcium concentration in the blood
kidney stones and osteoporosis, and heart diseases
how is high concentration of calcium in the blood treated
by using bisphosphonates, that cause calcium to to accumulate in the bones, thereby reducing the concentration of calcium in the blood
osteoclasts
cells that break down bones, causing calcium to be released into the blood
dialysis
the process of removing nitrogenous waste and excess water from the blood
how many types of dialysis are there? state them
2
Haemodialysis
Continuous ambulatory peritoneal dialysis(CAPD)
haemodialysis
in haemodialysis, a dialysis machine is used to separate the blood to be cleaned and the dialysis fluid with a selectively permeable membrane
describe what happens in haemodialysis
blood is taken from an artery in the arm
blood is passed through thousands of narrow fibres(artificial capillaries) made from selectively permeable dialysis tubing
the fibers are surrounded by dialysis fluid
the pores of the tubing allow small molecules to move through but not larger molecules such as blood cells, platelets pr proteins
the blood and the fluid run through the machine in opposite directions, which encourages the diffusion of substances out of the blood. this is a counter-current mechanism
the blood is returned to the vein
heparin is added to the blood to thin it and prevent clotting
the dialysis fluid has the same water potential as the blood but has a lower ion concentration and no urea. this creates a concentration gradient between the blood and the dialysis fluid
ions and urea diffuse down their concentration gradients, out of the blood via pores in the dialysis tubing and into the dialysis fluid. This happens until equilibrium is reached
water follows by osmosis down it’s water potential gradient
no glucose diffuses out of the blood as the dialysis fluid has the same glucose concentration as the blood
fresh dialysis fluid constantly passes through the machine in order to maintain the concentration gradient and the used fluid is discarded.
why is CAPD termed ambulatory
because the patient can walk around and be active whilst it’s being carried out
describe what happens in CAPD
this form of dialysis uses the peritoneum, a layer of tissue that lines the abdomen. it has a rich supply of blood and acts as the dialysis membrane
a catheter is inserted into the abdominal cavity and dialysis fluid is passed into the abdominal cavity
ions and urea pass from the blood in the capillaries into the dialysis fluid
after 40 minutes, the fluid is drained from the abdomen using gravity, into an empty bag
the fluid is changed about 4 times each day
make 4 comparisons between hemodialysis and CAPD
Haemodialysis takes several hours while CAPD is less time consuming
With Haemodialysis, the patient is unable to carry out other activities while with CAPD, the patient can carry out normal activities
More expensive machinery is needed for Haemodialysis
Haemodialysis is more efficient in removing salts, urea and excess water
there is a greater risk of infection of the peritoneum in CAPD due to the catheter
CAPD can be carried out at home, so fewer visits to the hospital are required
is water reabsorbed in the PCT
yes some water is
how do desert animals get water from dry seeds? ( don’t try to understand this, just learn it)
through respiration of the seed
through consumption of the fats and oils of the seed
via the metabolic water of the seed
effect of a large loss of blood from the body on the filtration rate of an organism
Hydrostatic blood pressure will decrease
The filtration rate decreases as a result, as there is not as much pressure to force out the same volume of filtrate as before
advantages of uric acid( apart from it being less toxic than the other forms of excretion)
it reduces body mass
it is light for flight
it has little mass, so it is easy to store
drugs that increase blood pressure and how they do it
ACE( Angiotensin-converting enzyme) and ARBs(angiotensin-receptor blockers): they reduce the effect of the hormone angiotensin which causes blood vessel constriction, thereby increasing pressure in the vessels
suggest conditions that can lead to ADH secretion
Blood loss
vomiting
explain how the nephron and its blood supply are adapted for ultrafiltration
blood in the glomerulus has a high hydrostatic blood pressure
glomerular capillaries have fenestraes to let the glomerular filtrate out
the basement membrane has podocytes and pedicels to increase the filtration rate
the basement membrane of the glomerulus is permeable to small molecules like water and glucose
it has a glomerulus that forces the glomerular filtrate out of the blood traveling at a high hydrostatic blood pressure
suggest why a patient with kidney disease might be advised to have a diet low in sodium chloride
excess salt would not need to be removed
high salt in diet could cause high blood pressure
ADH is released by the anterior pituitary gland, true or false
false, it is released by the posterior pituitary gland
how are chloride ions selectively reabsorbed
by facilitated diffusion through channel proteins, down their concentration gradient
how is water selectively reabsorbed
by osmosis down it’s water potential gradient, through a partially permeable membrane
how are sodium ions selectively reabsorbed
actively transported out of the cell through sodium-potassium pumps
reabsorbed by facilitated diffusion through channel proteins
ATP is used
how are glucose and amino acids selectively reabsorbed
by facilitated diffusion, down their concentration gradient through channel proteins, coupled with sodium ions which were actively transported out of the cell.
suggest how sodium chloride and glucose improve reabsorption in the kidneys
the more glucose and sodium chloride consumed, the more there will be in the blood.
so more glucose and sodium chloride will be present in the glomerular filtrate after ultrafiltration
more glucose co-transported
water potential lowered, so more water is reabsorbed by osmosis
