chapter 15 - homeostasis(liver and kidney) Flashcards
What is excretion?
- The removal of waste products from the body e.g. Urea and CO2
What are the functions of the liver?
- Excretion
- Detoxification(breaking down harmful substances into less harmful ones)
- glycogenesis(storing excess glucose as glycogen)
Name the structure of the liver
- hepatic portal vein
- hepatic artery
- hepatic vein
- gall bladder
- bile
What is the role of the hepatic artery, hepatic portal vein and hepatic vein?
- hepatic artery, carries oxygenated blood for respiration
- hepatic portal vein, blood carrying a high concentration of digested food
- hepatic vein, carries deoxygenated blood away from the liver
what is the role of the gall bladder and bile?
- gall bladder, stores bile
- bile, emulsifies fats
What does a liver lobule consist of?
- hepatic artery
- hepatic portal vein
- sinusoid
- bile duct
- kupffer cells
- hepatocytes
- central vein
What are the roles of the kupffer cells and hepatocytes?
- kupffer cells, are resident macrophages that break down bacteria
- hepatocytes, detoxification(breaking down toxic substances)
What occurs at the sinusoid?
- the blood from the hepatic artery and hepatic portal vein mix flowing towards the central vein
What is deamination?
- its the removal of the amine group from an amino acid
What happens to the amine group after deamination?
- the amine group is converted into ammonia which enter the ornithine cycle
What is the purpose of the ornithine cycle?
- To convert ammonia into urea so it can be excreted
What happens in the ornithine cycle?
- Ammonia combines with CO2 and ornithine to produce citruline
- citruline leaves the mitochondria and is the converted into arginine
- Arginine combines with water to produce ornithine whilst releasing urea
- A high concentration of urea decreases the water potential of the blood as result increasing water reabsorption by the kidneys
Where does deamination occur?
- it occurs in the mitochondria of the liver cells
what is the process of ultrafiltration?
- High hydrostatic pressure is created as the afferent arteriole is wider than the efferent arteriole
- small molecules are forced into the Bowmans capsule to form the filtrate(glucose, H20, amino acids, urea and ions)
- large molecules don’t fit through the gaps(RBC and proteins)
What layers of protection ensures that no large molecules enter the Bowmans capsule?
- Gaps in the capillary walls
- Gaps in the basement membrane
- Gaps in the podocytes
what is selective reabsorption?
- its where useful products are reabsorbed from the glomerular filtrate by the nephron
What structural feature does the PCT have which ensures reabsorption?
- it has microvilli which increases the surface area for reabsorption
what processes do the molecules of the filtrate undergo during selective reabsorption?
- Glucose, amino acids and NA - active transport
- Water - osmosis
- Cl - diffusion
What does the nephron consist of?
- Bowmans capsule
- PCT
- Loop of henle
- DCT
- Collecting duct
Where region is the medulla and cortex in the kidneys?
- medulla, the inner region
- cortex, the outer region
What is the role of the DCT?
- balancing the H20 and salt needs of the body
- osmoregulation
what happens in the descending limb of the loop of henle?
- permeable to water
- Water moves out by osmosis meaning the salt concentration inside the loop increases
- water is absorbed into the capillaries
- hypertonic point is reached
What happens in ascending limb of the loop of henle
- Na and Cl pumped out by active transport
- which decreases the water potential of the medulla
- making the loop impermeable to water (water can’t leave by osmosis)
- isotonic point is reached
Dessert animals have longer loop of Henles, what does this mean?
- more water is reabsorbed
- more concentrated urine
What effect does ADH have on the collecting duct?
- it changes it permeability to water
What is the process of osmoregulation when someone is dehydrated?
- blood has a low water potential
- detected by the hypothalamus
- pituitary gland secretes ADH
- ADH carried in the bloodstream
- ADH binds to specific receptor proteins on the collecting duct
- increasing the permeability to water
- Water moves out of the collecting duct by osmosis
What are the causes of kidney failure and what is used to measure kidney failure?
- high blood pressure
- kidney infection
- glomerular filtration rate(GFR) is used to measure kidney failure
What is an implication caused by the kidney not being able to filtrate?
- blood will have increased urea and ions which can be fatal
What is an implication caused by the kidney not being able to reabsorb?
- the blood will have decreased urea, H20, ions
What treatments are there for kidney failure?
- renal dialysis
- kidney transplant
How are patients treated using renal dialysis?
- patients blood passed through a partially permeable membrane (surrounded by dialysis fluid)
- urea and waste products diffuse out
- glucose, water and ions return to normal concentration
What are the disadvantages to renal dialysis?
- its expensive
- patients fell unwell
- inconvenient
- time consuming (2,3 times per week)
What are the conditions required for kidney transplant and what are the implications caused if this condition isn’t met?
What can be done to help such implications?
- Donor must have the same blood type as the recipient
- if its not the same then the immune system will reject it
- immune suppressant drugs can be provided to control this
What are the advantages and disadvantage of kidney transplant?
- more convient for patient
- full recovery sometimes
- cheaper in the long term
- better quality of life
- disadvantage, there is a long queue to find a donor
Explain the process of how pregnancy test sticks can show results
- if HCG is present, HCG attaches to mobile complementary antibodies to form HCG antibody complex
- it then moves along the test stick and attaches to the immobolised monoclonal antibodies
- a maker becomes visible if the HCG is present
- the urine continues until it reaches the second window
- here there are immobilised monoclonal antibodies that bind to the mobile antibodies regardless if HCG is bound to it
- A line will appear here indicating the test worked
What can be tested for in excretory products?
- pregnancy
- steroids
- drugs
In renal dialysis, why is it important there is a counter-current flow?
- it maintains a high concentration gradient
- ensures the maximum removal of waste products
In renal dialysis, why is the addition of Anti - coagulant to the blood important?
- it ensures the blood flows smoothly
What are the differences and similarities between the PCT and DCT?
- both use active transport
- both involve co-transport proteins
- both involve selective reabsorption
- PCT moves glucose
- DCT moves ions only
- DCT involves the use of Calcium ions
What are the similarities and differences between the tissue fluid formation and ultrafiltration?
- both processes involve a basement membrane
- both processes involve high hydrostatic pressure
- both processes have a hydrostatic pressure which is greater than the oncotic pressure
- both processes large molecules can’t be filtered and so remain in the blood
- many molecules are reabsorbed back into the capillaries
- ultrafiltration, has 3 layers of filtering the blood(podocytes, basement membrane and capillary walls) whereas tissue fluid formation only has the basement membrane
- knot of capillaries in ultrafiltration, network of capillaries in tissue fluid formation
