Bio U4 Excretion Flashcards
What are the effects of excess CO2
Excess CO2 is toxic
Reduces oxygen transport
Produces CARBAMINOHAEMOGLOBIN
Respiratory Acidosis
Function of the gallbladder
Stores BILE made by the liver
Bile emulsifies fats
Hepatocytes
Carry out hundreds of metabolic processes and the liver has a important role in homeostasis
Hepatic artery
Carries oxygenated blood from the heart
Hypatia portal vein
Carries deoxygenated blood from the digestive system
Carries blood away from the liver
What are hepatocytes
Liver cells
👀remove some molecules from the blood and pass other molecules into the blood
👀contain many mitochondria needed for a large supply of ATP
👀contain many ribosomes for protein synthesis
Sinusoids
Where oxygenated blood from the HEPATIC ARTERY and deoxygenated blood from the HEPATIC PORTAL VEIN are mixed
Kupffer cells
Specialised macrophages involved in the breakdown and RECYCLING of old red blood cells.
One product of haemoglobin is the breakdown of bilirubin which gives faeces it’s brown colour
Break down of proteins
Amino acid->ammonia keto acid->urea
(Deammination) (Ornithine cycle)
Deamination
Amino acid+O2->ketoacid+ammonia
Ammonia is very toxic and very soluble
Ornithine cycle
NH3 + CO2 —>CO(NH2)2 + H2O
The liver has…
Many enzymes that render toxic molecules less toxic
Catalase
Converts hydrogen peroxide to oxygen and water
Ethanol dehydrogenase
Breaks down ethanol to Ethanal
Outline detoxification
Ethanol->EthAnAl->ethanoic acid->ACETYL COENZYME A
ACETYL coenzyme A is non toxic and is used in respiration
What are the components of the nephron
Glomerular Capillary PCT- proximal convoluted tubule Renal bowman's capsule Loop if Henle Descending Limb Ascending limb DCT- distal convoluted tubule collecting duct (releases urine)
Renal bowman’s capsule
Cup shaped structure that surround the glomerulus
Proximal convoluted tubule
Site of SELECTIVE REABSORPTION where certain substrates are reabsorbed
Loop of Henle
Loop that creates a counter current flow, and makes salt transfer between limbs more efficient
Distal convoluted tubule
Where SOME water is reabsorbed into the blood
Collecting duct
Site if A LOT of water reabsorption
Afferent Arteriole
Brings blood to the glomerulus
Glomerulus
Capillary network and site of ultrafiltration
Efferent Arteriole
carries AWAY from the glomerulus
Peritubular
Surround the nephron
Some substances move from the filtrate back into the blood
Define Ultrafiltration
Filtration at the molecular level in the glomerulus of the kidneys
Outline ultrafiltration
The Afferent Arteriole has a WIDER DIAMETER than the Efferent Arteriole
This difference in diameter creates a high HYDROSTATIC pressure in the glomerulus
The high hydrostatic pressure forces some substances out of the blood. The pass through the PORES in the CAPILLARY across the BASEMENT MEMBRANE and through the PODOCYTES
PODOCYTES have major processes which INCREASE surface area
⚡️proteins and red blood cells are too big to pass through
⚡️water, amino acids, glucose, urea, and ions can pass through
Outline selective reabsorption
Na+ is actively transported into the blood from the cells lining the PCT
This lowers the concentration of Na+ inside these cells
As a result Na+ moves from the filtrate into the cells through co-transporter proteins and brings glucose or a amino acid into the cell
These are transported into the blood
Outline water reabsorption
Na+ and Cl- are actively transported out of the ascending limb
This lowers the water potential of the blood surrounding the nephron and causes water to move out of the descending limb into the blood by osmosis. Water is unable to leave the ascending limb because it is impermeable to water
This creates a very negative water potential in the base of the loop of Henle
As a result, little Na+ and Cl- move out of the ascending limb by diffusion
When the filtrate reaches then DCT the water potential is very high due to so much Na+ and Cl- being pumped out of the ascending limb
Water is drawn out of the DCT and collecting duct depending on the level of ADH in the blood
Selective reabsorption
- where does most reabsorption occur
85% of filtrate is reabsorbed in the PCT
cells lining the PCT are specialised to achieve this reabsorption
Outline The Hypothalamus and Posterior Pituitary
💭ADH is manufactured in the cell body of the neurosecretory cells. ADH flows down the axon to the terminal bulb in the posterior pituitary gland. Stored here until needed.
💭water potential of the blood is monitored by osmoreceptors in the hypothalamus of the brain. These cells respond to the effect of osmosis. When water potential of the blood is very low the osmoreceptors lose water by osmosis. This causes them to shrink and stimulate the neurosecretory cells in the hypothalamus.
💭when the neurosecretory cells are stimulated they send action potentials down their axons and cause the release of ADH
The effect of ADH on the collecting duct wall
ADH is detected by the cell receptors
Enzyme controlled reactions
Vesicles containing water permeable channels(aquaporins) fuse to the membrane
More water is reabsorbed
Osmoregulation
The control of water levels and salt levels in the body
Antidiuretic hormone
ADH
Released from the pituitary gland and acts on the collecting ducts in the kidneys to increase their reabsorption of water
Osmoreceptors
Receptor cells that monitor the water potential of the blood
If the blood has a low water potential, water is moved out of the osmoreceptors cells by osmosis, causing them to shrink
This causes stimulation of neurosecretory cells
Hypothalamus
part of the brain that contains neurosecretory cells and various receptors that monitor the blood
Neurosecretory cells
Are specialised cells that act like nerve cells but release hormones into the blood
ADH is manufactured in the cell body and passes down the axon to be stored in the terminal bulb
If an action potential passes down the axon then ADH is released from the terminal bulb
Posterior pituitary gland
Releases ADH
Fall in water potential
If the water content of the blood drops, the water potential drops
This is detected by the osmoreceptors in the hypothalamus
The POSTERIOR PITUITARY GLAND is stimulated to release MORE ADH into the blood
More ADH means the collecting duct walls are more PERMEABLE so more water is reabsorbed I to the blood by osmosis
Small amount of highly concentrated urine is produced and less water is lost
Rise is water potential
Water content rises so the water potential rises
Detected by the osmoreceptors in the hypothalamus
POSTERIOR PITUITARY GLAND releases LESS ADH into the blood
Less ADH means the collecting duct walls become less permeable so less water is reabsorbed into the blood by osmosis
Large amount of dilute urine is produced and more water is lost
What are some reasons for kidney failure
Diabetes mellitus
Hypertension
Infection
What happens when kidneys fail completely
Body fills with extra water and waste products
Hands and feet swell
Patients feel tired and weak because body needs clean blood to work effectively
If not treated could lead to death
What are benefits of the kidneys
They keep your blood composition constant
Filter blood to remove excess water and waste products
1/4 of your blood supply passes through your kidneys each minute
Dialysis
Any substances in excess in the blood diffuse across the membrane and into the dialysis fluid (through artery)
Any substances that are low in concentration diffuse into the blood from the dialysis fluid through diffusion
An ANTICOAGULANT is added to the blood to prevent it from clotting
a patient needs 3-4 dialysis sessions per week and last 4-5 hours each
Blood and dialysis fluid move in opposite directions in a counter current flow to maintain a steep concentration gradient
Treatment of kidney failure through Transplant
The transfer of a healthy kidney from one person into the body of the patient
Best chance of success is when the healthy kidney is taken from a LIVING RELATIVE as this reduces the chance of rejection.
The body would recognise the new kidney as FOREIGN and eventually reject it
What are the advantages of a kidney transplant
1⃣Freedom from time consuming dialysis
2⃣less limited diet
3⃣feeling better physically
4⃣better quality of life
5⃣no longer seeing oneself as chronically ill
What are the disadvantages of kidney transplant
Need IMMUNE-SUPPRESSANTS for the life of the kidney
Need major surgery under a general anaesthetic
Risks of surgery include; infection, bleeding, and surround organ damage
Frequent checks for signs of infections
There are side effects - anti-rejection medicine causes fluid retention and high BP
Immune suppressants incense susceptibility to infection
Outline pregnancy testing
Test for hormone hCG (human chorionic gonadotropin) is secreted by growing embryo
hCG binds to the antibodies on the beads of the pregnancy strip
The urine moves up the test strip carrying the beads with it
If there is hCG present the strip would turn blue because the immobilised antibodies bind to the hCG, concentrating the blue beads in the area
Anabolic steroids
Anabolic steroids increase protein synthesis within cells resulting in the build up if muscle tissue
They have dangerous effects like liver damage
What is a test for testing for anabolic steroids and how is it carried out
GAS CHROMATOGRAPHY
urine sample is vaporised and passed through a column surrounded by cool liquid
Different substances move through the column at different rates
The length of time taken for the substances in the sample to pass through the column is compared to the time taken for a STEROID to pass through the column
define excretion
The removal of METABOLIC waste from the body
