Module 5.2 - Excretion Flashcards
What is excretion? (2)
- The removal of waste products from the body
- Excretion maintains normal metabolism and homeostasis
Functions of the liver? (2)
- Deamination
- Detoxification
Deamination? (3)
- Nitrogen-containing amino groups are removed from amino acids
- Nitrogen can’t be stored in the body
- Forms ammonia and organic acids
What happens to organic acids? (2)
- Organic acids are respired to give ATP
- Converted to carbohydrate and stored as glycogen
What happens to ammonia? (2)
- Ammonia is toxic
- It is combined with CO2 in the ornithine cycle to create urea
Where does the ammonia + CO2 stage of the ornithine cycle take place? (2)
- Mitochondria of liver cells
- Other stages take place in the cytoplasm
What happens to urea after the ornithine cycle? (3)
- Released from liver into blood
- Kidney filters blood and removes urea as urine
- Urine is excreted
Detoxification? (1)
- Breaks down alcohol, drugs and unwanted hormones
What happens to ethanol (alcohol)? (1)
- Ethanol is broken down into ethanal is broken down into acetic acid
What happens to the body if there is excess alcohol, drugs and unwanted hormones? (3)
- Excess alcohol can cause cirrhosis (liver die and scar tissue blocks blood flow)
- Dugs such as paracetamol can lead to liver and kidney failure
- Unwanted hormones such as insulin can effect blood sugar levels
Structure of liver? (6)
- Hepatic artery
- Hepatic vein
- Hepatic portal vein
- Bile duct
- Lobules
- Sinusoids
Function of the hepatic artery? (1)
- Oxygenated blood from heart to liver
Function of the hepatic vein? (1)
- Deoxygenated blood from liver to heart
Function of the hepatic portal vein? (1)
- Brings blood from duodenum and ileum which are rich in digested food to be filtered out
Function of the bile duct? (1)
- Bile ducts takes bile to gall bladder for storage
Connection between hepatocytes and the bile ducts? (1)
- Hepatocytes produce bile and release them into bile canaliculi which drain into bile ducts
Structures of the lobules? (3)
- Cylindrical structures made of hepatocytes
- Has a central vein in the middle that connects to the hepatic vein
- Has branches of hepatic artery, portal vein and bile duct attached to each lobule
What are sinusoids? (2)
- Capillaries that connect the hepatic artery and hepatic portal vein
- Has Kupffer cells
Kupffer cells (2)
- Cells that are attached to sinusoids
- Remove bacteria and breakdown old red blood cells
How are sinusoids and hepatocytes involved in excretion? (2)
- Blood runs through sinusoids and past hepatocytes removing harmful substances and oxygen
- Hepatocytes breakdown harmful substances and re-enter them into the blood
What does the liver look like under a microscope? (4)
- Central vein: white circular shape
- Hepatocytes: spread out from central vein
- Nucleus: red dots
- Sinusoids: white spaces
Functions of the kidney? (2)
- Excretion of waste products
- Regulate water potential
How does the kidney excrete waste products? (6)
- Blood enters kidney through renal artery
- Ultrafiltration
- Selection reabsorption
- Unwanted substances pass along tubules & ureter to the bladder
- Unwanted substances are excreted as urine
- Filtered blood pass out of kidney through renal vein
Ultrafiltration? (2)
- Blood passes through capillaries in the cortex from renal artery
- Substances are filtered out into long tubules that surround capillaries
Selective reabsorption? (3)
- Useful substances are reabsorbed back into the blood from tubules in medulla and cortex
- Takes place when filtrate flow along proximal convoluted tubule (PCT), through the loop of Henle and distal convoluted tubule (DCT)
- Epithelium of PCT has microvilli for increased larger surface area for reabsorption
What transport mechanism are useful substances reabsorbed by? (3)
- Glucose, amino acids, vitamins and some salts are reabsorbed via active transport and facilitated diffusion
- Some urea is reabsorbed by diffusion
- Water enters blood via osmosis
Why reabsorbed via osmosis? (1)
- Water potential of blood is lower than filtrate
Where is water reabsorbed from? (3)
- Loop of Henle
- DCT
- Collecting ducts
Nephrons? (3)
- Network of long tubules and capillaries
- Where blood is filtered
- Abundant in number
Role of the nephrons in blood filtration? (4)
- Blood enters the afferent arterioles in cortex from renal artery
- Each afferent arterioles splits into glomerulus where ultrafiltration takes place
- The efferent arterioles takes the blood out of the capillaries and into the Bowman’s capsule
- Filtrate pass along the rest of the nephron and useful substances are reabsorbed
From where are useful substances reabsorbed to and from? (1)
- Useful substances leave tubules of nephron and enter capillary network around it
Filtrate? (1)
- Liquid and small molecules
What happens to the filtrate after filtration? (2)
- Filtrate that remains after selective reabsorption is urine
- Which flow through collecting duct and pass along ureter to bladder to be expelled
Components of urine? (5)
- Water
- Dissolved salts
- Urea
- Hormones
- Excess vitamins
What enters the Bowman’s capsule? (2)
- Filtrate enter the nephron tubules, the capillary wall, the basement membrane before entering the Bowman’s capsule through its epithelium
- Larger molecules can’t pass through these layers and thus stay in the blood
Glomerulus? (1)
- Bundle of capillaries looped inside Bowman’s capsule
Afferent arterioles? (1)
- Takes blood into the glomerulus
Efferent arterioles? (2)
- Smaller in diameter and is under higher pressure than afferent
- Its high pressure forces filtrate out of the capillary into the Bowman’s capsule
The cortex under a microscope? (4)
- Glomerulus: bundle of capillaries
- Bowman’s capsule: white area around glomerulus
- PCTs and DCTs: circular areas surrounded by squamous epithelial cells
- Nuclei: purple blobs
What happens if the body is dehydrated? (3)
- Water potential of blood is too low
- More water is reabsorbed into blood from nephron tubules
- Urine is more concentrated - less water is excreted
What happens if the body is too hydrated? (3)
- Water potential of blood is too high
- Less water is reabsorbed into blood from nephron tubules
- Urine is more dilute - more water is excreted
By what transport mechanism is water reabsorbed by? (1)
- Water is reabsorbed via osmosis into the blood from the tubules of the nephrons
Loop of Henle? (3)
- Descending limb
- Ascending limb
- Limbs help set up counter current multiplier mechanism
Counter current multiplier mechanism? (1)
- Mechanism that reabsorb water
Counter current multiplier mechanism at the top of the ascending limb? (3)
- Na+ & Cl- diffuse out of medulla at top of ascending limb
- Water stays inside tubule as ascending limb is impermeable to water
- Creates low water potential in medulla
Counter current multiplier mechanism at the descending limb? (4)
- Water moves out of descending limb into medulla via osmosis
- Due to lower water potential in medulla than in descending limb
- Filtrate becomes more concentration
- Water is reabsorbed into blood through capillary network from the medulla
Counter current multiplier mechanism at the bottom of the ascending limb? (3)
- Na+ & Cl- diffuse out of medulla at the bottom of ascending limb
- Lowering watering water potential in medulla
- Water stays inside tubule
Counter current multiplier mechanism at collecting duct? (3)
- Water to moves out of collecting duct via osmosis
- Due to lower water potential in medulla than in collecting duct
- Water is reabsorbed into blood through capillary network from the medulla
What is an adaptation of the loop of Henle for animals who live in areas of low water? (4)
- Longer loops of Henle
- Long the ascending limb the more ions that can be pumped out
- The more water that can be reabsorbed
- Animal can save more water
ADH? (1)
- Antidiuretic hormone
ADH level when dehydrated? (8)
- Water potential of blood drops
- Detected by osmoreceptors in hypothalamus
- Posterior pituitary gland is stimulated to release ADH
- ADH level rises
- ADH makes DCT and collecting duct walls more permeable to water
- More water can be reabsorbed from these tubules to medulla
- Small amount of highly concentrated urine formed
- Less water is loss
ADH level when hydrated? (8)
- Water potential of blood rises
- Detected by osmoreceptors in hypothalamus
- Posterior pituitary gland is stimulated to release less ADH
- ADH level lower
- Less ADH makes DCT and collecting duct walls less permeable to water
- Less water can be reabsorbed from these tubules to medulla
- Large amount of dilute urine formed
- More water is loss
What is kidney failure? (1)
- Kidney can’t carry out normal functions properly
Glomerular filtration rate (GFR)? (3)
- Can be detected by measuring glomerular filtration rate (GFR)
- GFR is the rate at which blood is filtered into the Bowman’s capsule from the glomerulus
- A lower rate can indicate and faulty kidney
Causes of kidney failure? (2)
- Infections: inflammation which damages cells, interfering with filtration in the Bowman’s capsules or reabsorption in parts of the nephron
- High blood pressure: can damage the glomeruli capillaries causing larger molecules to enter capillary walls and into urine
Consequences of kidney failure? (4)
- Waste products build-up
- Parts of the body swell as fluid accumulate in tissues
- Unbalance of electrolytes
- Long term kidney failure can cause anaemia
Consequence of too much urea in the blood? (1)
- Weight loss and vomiting
Examples of the consequence of unbalanced electrolytes? (2)
- Imbalance of Ca2+ and P3- can lead to brittle bones
- Salt build-up can cause more water retention
Treatment options of kidney failure? (2)
- Renal dialysis
- Kidney transplant
Renal dialysis? (4)
- Haemodialysis
- Peritoneal dialysis
- Keep a person alive until transplant is available
- Less risky than surgery
Haemodialysis? (6)
- Blood passed through dialysis machine
- Blood flows on one side of partially permeable membrane and dialysis machine flows through the other side
- Waster products, excess water and ions diffuse across membrane and into dialysis fluid
- Larger molecules are prevented from leaving
- Sessions take two to five hours and done two-three times a week
- One can feel unwell in between sessions
Peritoneal dialysis? (6)
- Dialysis fluid is put in a tube that passes from the abdomen into their abdominal cavity
- Waste products diffuse out of patient’s blood into dialysis fluid across the peritoneum
- Fluid is drained out of the tube
- Several times a day or one long session overnight
- Risk of infection
- No dialysis-free days
Peritoneum? (1)
- Membrane that lines the abdominal cavity
Kidney transplant? (5)
- Kidney needs to be same blood and tissue type of patient
- Living relative or dead person donor
- Transplants are cheaper than dialysis
- Major operation with high risk
- Immunosuppressants needed
How do pregnancy tests work? (5)
- Test strip containing monoclonal antibodies for hCG bound to blue bead
- Urine will bind to antibodies on the beads
- Urine moves up test strip taking bead up with it
- Antibodies-hCG will be stuck in place
- If hCG is present test strip will become blue as blue beads become concentrated in the are
hCG? (1)
- Human chorionic gonadotropin is a hormone only found in pregnant women’s urine
How do drug tests for steroids work? (6)
- Anabolic steroids build up in muscle tissue
- Gas chromatography/mass spectrometry (GC/MS)
- In GC urine is vaporised and passed through column containing a polymer
- Different substances move at different speeds - urine will sperate out
- One separated MS converts them into ions and will sperate them by its mass and charge
- Results will be analysed by a computer by comparing known substance to unknown substances to identify them
How do drug tests for recreational drugs work? (5)
- Can test for cannabis, ecstasy or cocaine
- Test strip containing antibodies for the drug being tested on
- Urine containing drug will bind o antibodies
- Colour change will happen for positive test
- If positive another test will be sent for GC/MS analysis
