5.2 Excretion Flashcards
Excretion
removing metabolic waste from your body (anything produced as a byproduct of a reaction)
Example of substance that needs to be excreted and how
co2 is excreted by breathing it out and nitrogen containing compounds like urea are excreted by the kidneys
Main excretory organs
Lungs, liver, kidneys, skin
Excretion w the liver
gets rid of toxins, plays big role in breaking down nitrogen containing compounds
Excretion w the kidney
Makes urine
Excretion w the skin
Sweat
Why’s excretion important
A build up of waste is toxic
What is the problem of excess co2 (not excreting co2)
it would combine w water to form carbonic acid and decrease the pH of your blood. Low pH would affect the proteins tertiary structure
Problem if not excreting nitrogenous compounds
amino acids are toxic so they’re broken down into something less toxic and less soluble = urea
Liver diagram
Portal triad
Hepatic portal vein, hepatic artery, bile duct at each lobule
Hepatic portal vein
brings deoxygenated blood from your digestive system.
Main function of liver
detoxification, clean blood
What is the liver divided into
Lobules
How are sinusoids formed
Hepatic portal vein and the hepatic artery enter the liver lobules they mix to form the sinusoid
What is the sinusoid lined w
Liver cells
What can be found inside the sinusoid
kupffer cells which are specialised macrophages
Hepatocytes
Liver cells
Hepatic artery
Bring in oxygenated blood
Hepatic portal vein
Brings deoxygenated blood rich in nutrients from the gut
Bile canaliculus
Bile flows from here to the bile duct
Sinusoid
Blood flows through here exchanging materials w endothelial cells and hepatocytes
Central vein
Blood flows from here into the hepatic vein
Liver lobule diagram
What do kupffer cells do to red blood cells
After 120 days, break down red blood cells bc they don’t have a nucleus so they can’t carry out protein synthesis
What causes change in the colour of a bruise
Haemoglobin changes colour
How would the blood entering the vein be clean
- By the time the blood travels through the sinusoid into your hepatic vein, hepatocytes would have worked to clean the blood so the blood entering the vein should be clean = no toxins
Where does the bile canaliculus take bile
drains into bile duct and bile can then go to digestive system or if your not eating anything the bile can be stored in the gallbladder
Bile
the breakdown products of red blood cell. RBC’S form bilirubin
Function of bile
Break down fat
Arrangement of cells in a lobule diagram
Intra-lobular vessel
If vessel is inside the lobule
Inter-lobular vessel
If the vessel is outside the lobule
Excretion (simplified)
removal of metabolic waste (digested) e.g. urea + co2
Egestion
removal of un digested waste that hasn’t entered the body
Where are liver cell receptors found
On every cell except red blood cells
HBA1C
The concentration of HbA1C is directly proportional to the mean concentration of glucose in the blood over an eight to twelve week period.
Functions of liver
- controls blood glucose levels bc it stores glucose as glycogen
- Synthesis of bile, cholesterol
- Synthesis of red blood cells in foetus
- Storage of vitamins (A,D) + minerals
- Detoxification of alcohol and drugs = as alcohol stays in the body is causes more damage since oh group is polar
- Breakdown of hormones
- Destruction of red blood cells
- Makes cholesterol from acytl co A = regulates fluidity of membrane + stores iron, copper, vitamins a,d
- Liver makes bile which makes fat globule into smaller fat droplets which makes it easier for
- Liver breaks down hydrogen peroxide using catalase.
Where does detoxification happen
On surface of smooth SER
Two key enzymes in detoxification
Catalase and cytochrome P450
Catalase
Breaks down hydrogen peroxide into oxygen and water
Cytochrome p450
Breaks down drugs
Alcohol
Ethanol
NAD
Coenzyme for the dehydrogenase enzyme = don’t have unlimited supply
Detoxification of alcohol
What else is NAD used for and what is this issue of running out of NADs
used in breakdown of fatty acids so if someone drinks too much alcohol they run out of NADs so fatty acids can’t be broken down = build up + leads to fatty liver
Formation of urea
Deamination
Keto acid
- can be used in respiration to yield energy (are respired). Keto acids can be converted to lipids and cholesterol
why can’t ammonia be transported in the blood
Highly toxic, highly soluble
Ornithine cycle
Why’s ammonia converted to urea
- urea is less soluble and less toxic than ammonia so it can be transported in the blood to the kidneys to be excreted
How does alcohol cause damage
breaks down phospholipid bilayer which damages the hepatocytes
Liver cells adaptions
Lots of mitochondria and endoplasmic reticulum
Why do liver cells have lots of mitochondria
to produce atp bc v huge metabolic role
Why do liver cells have lots of endoplasmic reticulum
To synthesise proteins and lipids
Kidney functions
- removal of waste products in the blood
- Controls water levels
- Osmoregulation
Functional unit of livers
Hepatocytes
Functional unit of kidneys
Nephron
How does everything move through the kidney
goes thru pelvis, into the ureter + passes out the body by the urethra
Kidney diagram
Nephron diagram
Stages of movement through the kidney
Ultrafiltration
Selective re absorption
Loop of henle
Distal convoluted tubule
Collecting duct
Where does ultrafiltration happen
At bowman’s capsule
What pressure is created during ultrafiltration and why
- Afferent arteriole has a larger diameter than efferent arteriole so creates a hydrostatic pressure which forces molecules out
Molecules forced out during ultrafiltration
water, amino acids, glucose, urea, any inorganic ions
Barriers between bowman’s capsule and glomerulus
Endothelium, basement membrane, epithelium of bowman’s capsule
Endothelium
lining of capillary + only has small pores, anything that’s large e.g. blood cells + large proteins + platelets can’t move out
What is the basement membrane made of
Collagen fibres and glycoprotein fibres
Basement membrane
doesn’t allow the passing of any molecules that have a molecular mass greater than 69000 or any proteins but allows amino acids to go through / proteins repelled by negative charge on the fibres.
Epithelium if bowman’s capsule
helps molecules move thru bc it has a specialised structure w cells known as podocytes = spread themselves out which allows the movement of molecules into the bowman’s capsule
What can pass through during ultrafiltration
Urea, amino acids, ethanol, vitamins can pass through
Where does selective re absorption happen
At PCT lumen
Filtrate
Any fluid inside nephron
PCT wall
Specialised wall made up of microvillis = increase surface area
What’s on the other side of PCT
Red blood cells
What should happen in selective re absorption
Take glucose back = useful
Selective re absorption
- Sodium ions pumped out of the wall of the PCT onto other side = creates sodium ion concentration gradient. High sodium ion concentration in lumen but not in wall So sodium diffuses in thru co transport w glucose or amino acids. Creates build up of glucose + amino acids so they diffuse into the blood. + water follows by osmosis. At the end of the PCT 100% of glucose and amino acids should be taken back into the blood
Adaptations of PCT
Cell membrane contains microvillis, cotransport proteins and sodium potassium pumps.
Un wall of PCT there’s loads of mitochondria
Why does the PCT membrane contain microvillis
Increase surface area for re absorption
Why does the PCT membrane contain co transport proteins
Allow transport of glucose and amino acids w sodium
Sodium potassium pump in PCT
Allows sodium gradient to be created
Loop of henle ascending limb
- impermeable to water
- at the top of the ascending limb, sodium ions and chloride ions are actively pumped out of the limb (requires ATP)
- At the bottom of the limb, sodium ions and chloride ions diffuse out
- Decreases water potential in the medulla
Descending limb loop of henle
- permeable to water
- Water potential outside lower than inside so water moves out by osmosis
- Some chloride and sodium ions can diffuse into the limb by diffusion
What is the aim of the loop of henle
to reduce the water potential in the medulla as much as possible. Bc once in medulla it will eventually enter back into the blood.
What happens once water potential in the medulla is reduced.
it can also move out of the collecting duct
Where would the loop of henle have the lowest water potential
At the bottom of the curve
Loop of henle adaptations
- organisms that live in warmer places that need to keep as much water as possible usually have a longer loop of henle
Counter current multiplier system in the loop of henle
increases efficiency of salt transfer from the ascending limb to the descending limb. = causing a buildup of salt in the surrounding tissue fluid.
Distal convoluted tubule
- concentration of ions are recalibrated = ions can be pumped in or out e.g. potassium in
Collecting duct
Water rebasorbed
What is Osmoregulation
- Process of controlling the water potential in your body
Osmoregulation process
- In ur brain u have hypothalamus and pituitary glands (can release hormones)
- Posterior pituitary gland releases ADH (anti diuretic hormone) and oxytocin (both made my hypothalamus)= only hormones released by posterior any other hormone released by pituitary gland is from the anterior pituitary gland
- ADH binds to the walls of the collecting duct, it causes the aquaporins to fuse w the cell membrane so more water routes to leave and enter the bloodstream = increase the permeability of the walls which means more water can be taken out back into your blood = less urine and more concentrated urine
How’s water gained
by drinking or eating or as a byproduct of reactions e.g. respirations
How’s water lost
through sweat, urine, breathing out and faeces
What detects water potential of the blood
Osmoreceptors in the hypothalamus
How does ADH bind to the walls of the collecting ducts
complementary receptors on the walls of the collecting duct. ADH binds to the receptors which triggers a series of enzyme reaction and this leads to the addition of water permeable channels onto the membrane. These water permeable channels are known as aquaporins.
Osmoregulation diagram
How does alcohol affect ADH
- inhibits ADH
- higher volume, less concentrated urine.
What can be used during blood tests to detect kidney failure
Glomerular filtration rate
Glomerular filtration rate
measure of the volume of blood which can be filtered through the glomerulus per minute = measure of creatinine levels
GFR in healthy person
90-120cm^3min^-1
GFR indicating kidney disease/ failure
below 60 = kidney disease could be chronic or temporary, below 15 kidney failure
What could kidney failure be due to
diabetes, heart disease (bc impact on pressure = can cause damage to vessels)
Treatment for kidney failure
kidney transplant or renal dialysis = artificially cleaning the blood
2 types of renal dialysis
haemodialysis, peritoneal dialysis
Electrolyte balance
if your kidney fails, the balance of ions is disturbed
CAPD
continuous ambulatory peritoneal dialysis
CCPD
continuous cyclic peritoneal dialysis
Haemodialysis
- take out their blood w a needle, put it through a dialyser = artificial capillary that has the right concentration of everything you need in the kidney. heparin injected in tube to prevent blood clotting
Peritoneal dialysis
- surgery to replicate the artificial capillary into a pouch in the stomach = permanent + you fill it w dialysis solution
Advantages of haemodialysis
- patients are regularly monitored
- helps reduce risk of fluid overload and possible symptoms
Disadvantages of haemodialysis
- very time consuming = done 2/3 times a week for around 5 hours
- many health risks e.g. blood clotting and low blood pressure
Advantages of peritoneal dialysis
- ability to do dialysis whenever
- less time consuming
Disadvantage of peritoneal dialysis
- need surgery
- risk of developing peritonitis = could lead to symptoms e.g. vomiting and fever
- could lead to weight gain bc of constant exposure of dialysis fluid within the peritoneal cavity.
Kidney transplant advantages
- doesn’t require repeated dialysis
- diet less limited
- better quality of life
- Patient is no longer chronically ill
Disadvantages of kidney transplant
- would have to take immunosuppressant drugs = shut down immune system = prone to more infections
- risks of surgery = risks e.g, infection, bleeding and damage to other organs
- risk of rejection = immune system attacks organ
- long term of immunosuppressant drugs
Urine analysis
- Use urine dipstick
- At glomerulus anything such as glucose, alcohol, drugs and hCG (pregnancy hormone) can pass through
- Check for anabolic steroids = You can use gas chromatography to further prove it
Pregnancy testing
- monoclonal antibodies all have a complementary binding site for the hormone hCG
- When hCG binds to the mobile antibodies and the immobile antibodies which creates one line and there’s a line that acts as a control zone = monoclonal antibodies bind to a surface that has complementary receptors = shows the test is working
Where does the collecting duct go
to ureter to urethra to get to the bladder
Rennin
Kidney creates and secretes this when blood pressure is too low
What does rennin cause?
Vasoconstriction
Increased ADH
Increased aldosterone
Activates thirst centre in the hypothalamus
Why does rennin cause vasoconstriction
smaller area = higher pressure
Why does rennin cause increased ADH
more permeable collecting duct so more water reabsorbed
Why does rennin cause increased aldosterone
mroe salt in blood stream = draws more water from surrounding cells increasing blood pressure
Why does rennin activate the thirst centre in the hypothalamus
- drink more water so blood pressure higher
A
C
How to tell the difference between hepatic artery and hepatic portal vein
Hepatic artery = narrow vessel
Hpv = larger, branched vessel
What happens between citrus line and arginine
NH3 is added, H2O is produced and atp is converted to AMP
Where does the first stag3 of the ornithine cycle take place
Mitochondria
Using liver tissue and hydrogen peroxide at room temperature
Why and how is catalase activity regulated inside liver cells
Why - large quantities hydrogen peroxide and high turnover number of catalase would mean vigorous reaction and lots of oxygen produced very quickly
How - isolation of catalase in peroxisomes = released in small quantities + cells can limit expression of catalase = limits enzyme concentration + reduces reaction rate
Gaps in tissue
Cell death
W = liver
X = pancreas
Y = skeletal muscle
N = central vein
O = hepatocytes
ii
Thin cells = short diffusion distance
D
Sodium ions and glucose are both reabsorbed into the blood from proximal convoluted tubules (PCTs) in the kidney.
i. A student designed an experiment to investigate the effect of temperature on the rate of glucose diffusion through dialysis tubing,
State two factors that would need to be controlled in this experiment.
Initial glucose concentration
Length of dialysis tubing
Fewer H+ ions in PCT cells = less co transport of na+ ions from lumen = no active transport of na+ ions into blood
ii
B,d
- already differentiated = in G0
- would alter number of gaps = alter ultra filtration bc molecules would move through slower
What features of adult stem cells make them suitable for regeneration of tissues in the kidney?
Multipotent = differentiate into any cell type within kidney
Describe the similarities and differences between ultrafiltration and the formation of tissue fluid.
Similarities
- small molecules filtered from blood
- many molecules reabsorbed back into capillaries
- high hydrostatic pressure
- large molecules remain in blood
Differences
- knot of capillaries in ultrafiltration but a network of capillaries in formation of tissue fluid
- Blood filtered through 3 layers in ultrafiltration, but only 1 layer in formation of tissue fluid
- Molecules that are not reabsorbed by capillaries form urine in the kidney, but molecules that are not reabsorbed from tissue fluid will, enter cells / form lymph.
Age bc kidney function declines w age
Gender bc men + women have diff muscle mass
If kidney damage is suspected, the patient’s urine is likely to be tested for the protein albumin.
Explain why the presence of albumin in the urine indicates kidney damage.
idea that large proteins, should remain in the blood / not enter, Bowman’s capsule / nephron
Which tubule (distal or proximal) has the highest concentration of urea
Distal because water’s reabsorbed into blood earlier in the nephron
Salted crisps + boiled sweets reduce w.p. Of blood = osmoreceptors in hypothalamus detect change in w.p. In blood + cause increased release of ADH
ADH causes production of aquaporins in collecting duct so more water’s reabsorbed
Milk increases w.p. Blood so less ADH is released
Water reabsorption in the kidney is controlled by the endocrine and nervous systems.
Aldosterone and ADH are hormones that act on the kidney.
Aldosterone causes sodium ions to be pumped from the collecting duct cells into tissue fluid.
Describe how the endocrine and nervous systems work together to increase water reabsorption from the collecting duct.
- hypothalamus causes release of ADH from pituitary and aldosterone from adrenal cortex
- ADH binds to receptors on cell membranes of collecting duct cells = increases permeability to water
- hypothalamus is part of nervous system = osmoreceptors in hypothalamus detect low w.p. In blood
Aldosterone:
- sodium ions pumped out of collecting duct cells = lowers w.p. In tissue fluid = conc gradient established = na+ reabsorbed from collecting duct lumen + water diffuses into collecting duct via osmosis
And which is most appropriate for person w type 2 diabetes
Y = reduces blood volume most bc lower conc of water bc more urines produced
- X because it doesn’t raise blood glucose concentration = no effect on it
Peritoneal walls made up of living cells so produces atp to carry out active transport
Dialysis membranes only allow diffusion
- have thin wall so will bulge
- large lumen as contains large volume of blood
- found closer to skin than arteries
Some bodybuilders use anabolic steroids to increase their muscle mass.
Suggest why anabolic steroids are effective when applied to the surface of the skin.
Skin has large surface area of absorption
Sterile are non polar so can cross phospholipid bilayer
Muscles are close to skin so short diffusion distance
Based on the findings in Fig. 19.2, the head of the IOC stated that:
-The IOC is succeeding in reducing the level of steroid abuse in professional sport.”
Evaluate this statement using the data in Fig. 19.2.
- general trend: reduction in % samples w testosterone from start to end of test (from 1988 - 1991: % samples w testosterone decreased as testing numbers increased
- after 1991 there’s an increase in % tests w testosterone
- correlation doesn’t show causation
- fewer samples w testosterone isn’t same as less incidence of abuse
Issues of validity:
- only short time was studied
- other steroids used and not detected
