Kidney Flashcards
Egestion
Removal of undigested food waste
Excretion
Removal of metabolic waste
Main excretory products
Urea and CO2
Why is it bad to have too much CO2
Changes pH of the blood by producing carbonic acid
How is CO2 exhaled
Transported to the lungs and exhaled
Can excess protein and amino acids be stored
No
Deamination
To access the energy the amino group NH2 is removed from an amino acid
Where does deamination occur
In the liver
First equation of deamination
Amino acid= keto acids and ammonia
Keto acid
NH2CH(R)COOH
Second equation of deamination
2NH3 + CO2 = CO(NH2)2 + H2O
Why is ammonia immediately combine with CO2 to make urea
Ammonia is highly toxic
What can Keto acid be used as
Can be used as a respiratory substrate or converted to glucose/fat
Where does urea cycle take place
Liver
What is the chemical compound of urea
CO(NH2)2
What controls urea cycle
Enzymes
Does urea cycle require ATP
Yes
Selective réabsorption
Taking back useful molecules from the filtrate in the nephron into the bloodstream
Ultrafiltration
Filtering small molecules out of the blood at high pressure and into the kidney nephron
Why is the afferent arteriole more vasodilated than the efferent arteriole
To let more blood enter than leave so there is a high pressure in the capillaries
Does the afferent arteriole let blood into or out of the glomerulus
Into
3 layers of ultrafiltration at the glomerulus
Capillary endothelium
Basement membrane
Epithelium lining bowman’s capsule
Structure and Adaptation of endothelium of capillaries
Lots of gaps between cells that water and small solutes including urea glucose and ions can pass through
Structure and Adaptations of basement membrane
Fine mesh if collagen fibres and glycoproteins prevents passage of molecules with a RMM of 68000 (blood cells and large protein)
Structure and adaptation of epithelial cells of bowman’s capsule- podocytes
Podocytes have finger like projections ( foot processes) and large gaps between cells forming a filtrate slit for filtrate to move into the capsule
Selective réabsorption in proximal convoluted tubule
1 Na+/K+ pump on capillary side removing Na+ from proximal convoluted epithelial cells into blood by active transport
2 Na move by facilitated diffusion into the cell in carrier protein from pct lumen. It brings glucose/aa with it through co transporter protein
3 glucose/aa diffuse out the other side of the cell into the blood capillary into plasma
4 réabsorption leads to a lower water potential in PCT cells and water enters by osmosis
Microvili on PCT adaptation
On the inner surface lining pct and folded basal membrane on epithelial cells- increase sa for efficient reabsorption
Co transporter cells in PCT adaptation
For uptake of useful solutes and ions (Na glucose amino acids)
Tight junctions in PCT adaptation
In between adjacent cells and holds them together so no fluid can pass between cells
Mitochondria in PCT adaptation
Supply the Na/K pumps in basement membrane with ATP to create a gradient for co-transporter protein
Blood capillaires in PCT adaptation
Very close to epithelia cells so short diffusion distance
What is réabsorbes from pct to blood
All glucose all amino acids all vitamins many sodium and chloride ions some water half the urea
why does ultrafiltration occur
a difference in wp between plasma in glomerular filtrate and filtrate in bowman’s capsule high wp in plasma in capillaries due to increase in pressure that outweighs the proteins increasing solute potential
whats bigger the afferent or efferent arteriole
afferent
what happens at the loop of henle
ions (Na and Cl) are pumped out by active transport out if thr ascenidng limb of rhe loop
where does reabsorption take place
proximal convoluted tubule
what structures are in the cortex
bowmans capsule, pct, dct
what structures are in the medulla
loop of henle collecting duct and pelvis
which hormone contols water reabsorption and reduces water loss in urine
ADH
where is ADH secreted
posterior pituitary gland
how does the first part of the distal convoluted tubule work
like the ascending loop of henle
how does the second part of the distal convoluted tubule work
like the PCT
what does dct do
in the dct Na ions are actively pumped from the fluid in the tubule into the tissue fluid and they pass into the blood. K+ are actively transported into the tubule. The rate at which they are pumped in and out of nephron regulates ion conc in blood. Na and K are important for nerve communication
osmoregulation
the control of the water potential of blood and tissue fluid by controlling the water content and the concentration of ions (mainly Na)
what receptors detect a change in wp of the blood
osmoreceptors
what happens when there’s a decrease in wp
nerve impulse sent to pituitary gland stimulating release of ADH
what kind of hormone is ADH
peptide
diuresis
production of dilute urine
what does ADH target
cells of collecting duct. ADH makes the luminal membranes of the collecting duct more permeable to water
How is the permeability of the collecting duct changed
increasing the number of aquaporins in the luminal membrane
ADH binds to receptor proteins stimulating the production of cyclic AMP which is a second messenger which activates a signalling cascade and aquaporin molecules are phosphorylated
The activation of aquaporins means the vesicles move towards the luminal membrane and fuse with it.
what cells are in islets of Langerhans
alpha and beta cells
in the islets of Langerhans what do a cells secrete
glucagon
in the islets of Langerhans what do b cells secrete
insulin
when would there be an increase in glucose
after a meal containing carbohydrates
what happens when there is an increase in glucose
a cells stop secretion of glucagon and b cells secret insulin. Insulin is carried to all parts of body in blood
insulin binds to a receptor on a csm and increase the rate the cells absorb glucose from blood converting into glycogen, insulin also increases the use of glucose in respiration
where are islets of Langerhans
endocrine tissue in pancreas
How can glucose enter cells
facilitated diffusion through transporter protiens called GLUT
what glut proteins do muscle cells have
GLUT 4
How do cells become more permeable to glucose
when insulin molecules bind to receptors vesicle with GLUT proteins are moved to membrane and fuse with it
what glut proteins do brain cells have
GLUT 1
what glut proteins do liver cells have
GLUT 2
what does insulin stimulate
the activity of glucokinase which phosphorylates glucose trapping it in the cell, it can be converted to glycogen
glycogenesis
synthesis of glycogen by addition of glucose monomers
what happens when there is a decrease in blood glucose concentration
a cells stop secreting glucagon and b cells secrete insulin
what happens when glucagon binds to receptor
conformational change in receptor that activates G protein and that activates adenyl cyclase. Adenyl cyclase is part of the cell membrane and catalyses the conversion of ATP to cyclic AMP
cAMP is a second messenger that binds to protein kinase A enzymes activating them. Active protein kinase A activate phosphorylase kinase enzymes by adding phosphate groups to them. Phosphorylase kinase enzymes activate glycogen phosphorylase and they catalyse the breakdown of glycogen to glucose
glycogenolysis
breakdown of glycogen by removing glucose monomers
gluconeogenesis
formation of glucose in the liver from non carbohydrate sources like aa and pyruvate and lactate
order of enzymes in the cascade
adenyl cyclase
cAMP (not enzyme)
kinase
glycogen phosphorylase
