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Bio Module 5 > Excretion 5.2* > Flashcards

Excretion 5.2* Flashcards

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1
Q

What is excretion?

A

The process of removing metabolic waste from an organism

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2
Q

What is the difference between excretion and egestion?

A

Excretion is removing waste that was produced from cells and egestion is removing waste from the digestive system

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3
Q

What is metabolic waste?

A

Substances produced from chemical reactions that may be toxic at high levels in the body

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4
Q

What are the functions of the liver?

A
  • controls glucose conc.
  • controls amino acid levels
    (deamination/ transamination)
  • controls lipid levels
  • removes toxins
  • removes unwanted proteins
  • produces bile from breakdown of RBC
  • synthesis of plasma proteins
    -synthesis of cholesterol
  • stores vitamines
  • synthesis of foetal RBC
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5
Q

What is the hepatic portal vein?

A

A small vein going from the small intestine to the liver carrying deoxygenated blood containing lots of nutrients so the liver can store the nutrients and detoxify the blood

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6
Q

What is the other vessel that leaves the liver but does not carry blood?

A

Bile duct

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7
Q

What is a sinusoid?

A

A wide capillary inside the liver lobule which is lined with hepatocytes

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8
Q

What are kupffer cells?

A

The are cells found in the sinusoids that act like phagocytes so engulf and digest old RBC and bacteria

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9
Q

Which blood vessel connected to the liver is the bigger one?

A

Vena cava

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10
Q

What shape do liver lobules have?

A

Hexagonal shape

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11
Q

How can you tell the difference between the bile duct and the blood vessels?

A

The bile duct is lined with hepatocytes too and does not connect to the sinusoid

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12
Q

What is the lumen of the vessel that carries the bile called?

A

Bile caniculus

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13
Q

What is transamination?

A

The process of turning one amino acid into another one

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14
Q

Why is transamination needed?

A

Diet does not always provide the exact amino acids that we need and transamination helps overcome this problem but some amino acids cannot be made

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15
Q

How man essential amino acids are there?

A

8

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16
Q

What happens to cholesterol in the liver?

A

It is used in cell membranes and excess cholesterol is excreted by the liver

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17
Q

What happens to glucose in the liver?

A

Only a limited amount can be stored as glycogen so any excess is converted into lipids for storage elswhere

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18
Q

What happens to protein hormones in the Liver?

A

They are deaminated in the liver

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19
Q

What happens to steroid hormones in the liver?

A

They are excreted in bile

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20
Q

How can toxins be made harmless?

A

through processes like oxidation, reduction or combining them with another molecule

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21
Q

What does the liver contain that helps detoxify substances?

A

enzymes such as catalase and cytochrome P450

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22
Q

What is cytochrome P450?

A

A group on enzymes used to breakdown drugs such as cocaine and medicenal drugs

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23
Q

What processes is cytochrome P450 used in other than detoxification?

A

Metabolic reactions such as the electron transport chain during respiration

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24
Q

What are the negatives of cytochrome P450?

A

It can interfere with other metabolic roles and can cause unwanted side effects of some medicenal drugs

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25
Q

What are the substances in the electron transport chain?

A

Ethanol - Ethanal - Ethanoic acid - Acetyl Coenzyme A - Respiration

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26
Q

What is the enzyme that catalyses the oxidation of ethanol?

A

Ethanol Dehydrogenase

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27
Q

What is the enzyme that catalyses the oxidation of ethanal?

A

Ethanal Dehydrogenase

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28
Q

What is NAD turned into during the oxidation of ethanol and ethanal?

A

Reduced NAD

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29
Q

What enzyme is needed to turn ethanoic acid into acetyle coenzyme a?

A

Coenzyme a

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30
Q

What happens to cause cirrhosis of the liver?

A

If too much ethanol builds up in the body and NAD cannot breakdown fatty acids, the fatty acids will be stored in the liver as fat. If this builds up enough it stops liver function which causes the liver to scar which is known as cirrhosis

31
Q

What is deamination?

A

The removal of the amine group

32
Q

What does NAD do during deamination?

A

NAD picks up the extra hydrogen from the ethanol and ethanal 2 times

33
Q

What happens to the hydrogen that NAD picks up?

A

It provides the hydrogen for the electron transport chain

34
Q

What is the process of proteins turning into urea?

A
  • Proteins broken down into amino acids by hydrolysis
  • amino acids broken down into ammonia by deamination
  • ammonia broken down into urea by ornithine cycle
35
Q

Why is ammonia turned into urea?

A

It is less toxic and is soluble so can be excreted from the body in urine

36
Q

What is the quation for ammonia turning into urea?

A

Ammonia + CO2 —> H2O + Urea

37
Q

What are the functions of the kidney?

A
  • filtration of waste products from the blood
  • homeostasis of water and ions
38
Q

What are kidneys made up of?

A

Nephrons

39
Q

What is filtered out the blood by the kidneys?

A
  • glucose
  • urea
  • ions
  • water
  • amino acids
40
Q

What is reabsorbed into the blood by the kidneys?

A
  • glucose (all)
  • ions (some)
  • water (some)
  • amino acids (all)
41
Q

What stays in the urine after being filtered out the blood?

A
  • urea
  • ions (some
  • water (some
42
Q

What are the components of the kidney?

A
  • cortex
  • medulla
  • pelvis
  • ureter
  • renal artery
  • renal vein
43
Q

What are the components of a nephron?

A
  • glomerulus
  • bowman’s/ renal capsule
  • proximal convoluted tubule
  • loop of henle
  • distal convoluted tubule
  • collecting duct
44
Q

What is the difference between afferent and efferent arteriole?

A

Afferent is going towards the nephron and efferent is going away

45
Q

What is ultrafiltration?

A

When small molecules and ions are filtered out of he blood into the renal capsule

46
Q

What does a triple filtration layer consist of?

A
  • endothelium of capillaries
  • basement membrane
  • epithelium of renal capsule
47
Q

What are the adaptations of the endothelium of the capillaries?

A
  • very thin
  • perforated with thousands of spores
  • provides a barrier to cells but not plasma proteins
48
Q

What are the adaptations of the basement membrane?

A
  • meshwork of collagen and glycoprotein fibres
  • water and small molecules can pass through
  • proteins are too large and are repelled by negative charges on the fibres
    (chronic high blood pressure can damage the fibres)
49
Q

What are the adaptations of the epithelium of the renal capsule?

A
  • made of cells which are modified for filtration
  • podocytes
50
Q

What are podocytes?

A
  • cells with foot like projections that wrap around capillaries and interlink with neighbouring cells
  • contain gaps called filtration slits (25nm wide) allowing filtered fluid to pass through
51
Q

Where does the majority of selective reabsorption happen?

A

Proximal convoluted tubule

52
Q

How is the nephron suited for reabsorption in the PCT?

A
  • cell surface membrane inside the nephron is highly folded
  • contains co-transporter proteins (transport glucose/ amino acids with Na+)
  • outer membrane is highly folded
  • contains sodium potassium pumps
  • mitochondria in cytoplasm
53
Q

What are the steps to reabsorption?

A
  • Na+ ions actively transported out of cells lining the tubule into tissue fluid
  • concentration of Na+ ions in cell cytoplasm decreases creating a concentration gradient
  • Na+ ions diffuse into the cell through a cotransport protein
  • glucose/ amino acids enter cells with Na+ ions by facilitated diffusion
  • glucose/ amino acids diffuse into blood capillary
  • water moves into cells by osmosis
  • glucose/ amino acids diffuse into blood
54
Q

What is the role of the loop of henle?

A

To decrease the water potential of the tissue fluid of the medulla (make it salty again), role of homeostasis

55
Q

What is counter current multiplication?

A

The process of using energy to generate an osmotic concentration that enables you to reabsorb water from the fluid inside the nephron and produce concentrated urine
- fluids flow in opposite directions
- multiplies osmotic gradient between fluid within the tube and tissue fluid in the medulla

56
Q

Where id the majority of the water reabsorbed?

A

Proximal convoluted tubule

57
Q

How does the loop of henle maintain a low water potential in the medulla?

A
  • the fluid in the nephron flows from the proximal convoluted tubule into the descending limb of the loop of henle
  • the membrane of the limb is permeable to water
  • water leaves the limb due to osmosis as the medulla has a much lower water potential creating a water potential gradient
  • as the fluid reached the bottom of the loop it now has a high concentration of ions and urea
  • as the fluid moves into the ascending limb of the loop of henle the membrane becomes impermeable to water
  • ions begin to leave the limb by facilitated diffusion
  • as the fluid moves up the limb the concentration of the ions in the medulla decreases so the ions start to get actively transported out of the limb
  • as the fluid reaches the collecting duct some more water is reabsorbed via osmosis
58
Q

What is the role of ADH?

A

To produce less urine

59
Q

Where are the target cells for ADH?

A

Distant convoluted tubule and collecting duct

60
Q

How is water potential in blood regulated by osmoregulation?

A
  • water in the blood is monitored by osmoreceptors in the hypothalamus
  • a lower water potential causes cells to shrink and stimulates neurosecretory cells
  • neurosecretory cells release ADH which is stored in the posterior pituitary gland
  • less ADH is released when water potential is high and more is released when water potential is low
61
Q

What are aquaporins?

A

Water channels

62
Q

How do aquaporins work?

A
  • they respond to the level of ADH
  • cells in the walls of the DCT and collecting duct have receptors for ADH
  • when ADH binds to the receptors it causes more aquaporins to fuse with the membrane of the cells
  • leads to more water being reabsorbed so urine is more concentrated
63
Q

How is the distant convoluted tubule adapted to its function?

A
  • cells have receptors for ADH so is involved in maintaining correct water potential in the blood
  • cells have lots of mitochondria to actively pump out Na+ ions into the body if it lacks salt (Cl- follows by diffusion down electrochemical gradient)
  • plays a role in balancing pH of the blood
64
Q

How does a pregnancy test work?

A
  • hCG bind to the mobile monoclonal antibodies that are also bound to a dye molecule
  • the antibodies move up the strip with the fluid until they reach the test zone
  • at the test zone there are immobilised antibodies that detect the antibodies that are already bound to hCG
  • if it detects them the antibodies release the dye causing a coloured line to appear on the strip (positive result)
  • antibodies that did not bind to the hCG continue moving up the strip until they reach the control zone
  • at the control zone there are immobilised antibodies that bind to antibodies that are not bound to hCG
  • the antibodies then release a dye again creating a line at the control strip showing that the test is not faulty
65
Q

What do anabolic steroids do?

A
  • Increase protein synthesis
  • banned from competitive sports
  • found in urine
  • stays in the blood for days
66
Q

How does gas chromatography tests work?

A
  • urine sample is vaporised with gas solvent and passed down the tube with absorbent lining
  • each substance dissolves differently in the gas and has a different retention time
  • eventually it is absorbed onto the lining and creates a chromatogram
  • the results can then be compared to the chromatogram of standard drugs
  • the first drug to show on the chromatograph is the most soluble
67
Q

What are the causes of kidney failure?

A
  • diabetes
  • infection
  • hypertension
68
Q

What happens if kidneys fail?

A

They can no longer remove excess water or waste products from the blood

69
Q

What are the three methods of treatment for kidney failure?

A
  • haemodialysis
  • peritoneal dialysis
  • kidney transplant
70
Q

How does haemodialysis work?

A
  • removes waste, excess fluids and salts by passing blood over a dialysis membrane
  • blood is taken from an artery and is passed into a machine
  • the machine contains the artificial dialysis fluid
  • heparin has been added to the blood to prevent it from clotting
  • any air bubbles have to be removed before the blood is returned to the body
  • carried out three times a week for 8 hours
  • it can be done at home
71
Q

How does peritoneal dialysis work?

A
72
Q

How does a kidney transplant work?

A
  • old kidneys are left in place unless they are at risk of causing cancer or infection
  • donor kidney can be from a living or dead donor
  • last 10 years
  • surgeons implant the new organ into the lower abdomen and connects it to the blood supply and bladder
  • patients feel immediately better after and it is the best life treatment
  • patients take immunosuppressants to help prevent the body’s immune system rejecting the organ
73
Q

What are the advantages of a kidney transplant?

A
  • freedom from time consuming renal dialysis
  • feeling physically better
  • improved quality of life as they are able to travel
  • improved self image and no longer have a feeling of being chronically ill
74
Q

What are the disadvantages of kidney transplant?

A
  • need to take immunosuppressant drugs
  • need for major surgery under general anaesthetic
  • need for regular checks for signs of rejection
  • side effects of immunosuppressants (fluid retention, high blood pressure and susceptibility to infections)

Bio Module 5 (7 decks)

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