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EXCRETION Flashcards

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1
Q

what is excretion

A

the removal of waste product

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2
Q

what are some waste product?

A

co2, urea, nitrogen containing compounds, bile fragments

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3
Q

what are the excretory organs?

A

lungs, liver, kidney and skin

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4
Q

why is excretion important?

A

because otherwise toxic product will build up altering the ph and therefore preventing the normal functioning of enzymes which may lead to death

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5
Q

in which form is carbon dioxide transported after production?

A

as carbonic acid since co2+h20= h3co3

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6
Q

what happens to the carbonic acis (H3CO3)

A

it dissociated it=nto h ions and HCO-3

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7
Q

what happens with the H ions released afterwards?

A

1 Bind with haemoglobin = HAEMOGLOBINIC ACID
haemoglobin 3d SHAPE IS CHANGED REDUCING ITS AFFINITY FOR O2

  1. affect pH
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8
Q

what happens to co2 that is not converted into hydrogencarbonate?

A

it bind with haemoglobin to form carbaminohaemoglobin

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9
Q

what happens when there is excess H+?

what happens when excess H+ are detected?

how do cell resist to pH change?

A

it reduces the pH

it is detected by the respiratory system which leads to an increasing breathing rate in order to remove co2

proteins act a s abuffer to resist pH change.

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10
Q

deamination process and what is the formula

A

is the process by which the toxic amino group in amino acid is removed.

amino acid + oxygen –> keto acid and ammonia

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11
Q

what happens to the ammonia produced during deamination?

A

it is converted into urea.
ammonia + co2 = urea + water

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12
Q

describe the liver.

A

1.made of HEPATOCYTES
2.composed of HEPATIC LOBULES and divided into LUBULES
3. the liver is connected to the heart and small intestine

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13
Q

what are the veins/arteries that connects liver to heart?

A

hepatic artery -rich of O2 and poor in nutrients
hepatic vein - poor in o2

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14
Q

what is the vein that connects the liver with the small intestine?

A

hepatic portal vein - poor in 02 and rich in nutrients, waste products

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15
Q

explain what you can find in a lobule

A

1 hepatic artery
2 hepatic portal vein
3 bile duct
4 hepatic vein (at the centre)
5 Kupffer cells - kill and recycle old rbc
6 sinusoid - gap between hepatocytes where hepatic artery, hepatic portal vein blood is mixed
7 hepatocytes - liver cells that release waste product and intake nutrients from blood

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16
Q

what are the main liver functions?

A
  1. storage of glucose - in the form of glycogen
  2. detoxification of harmful substances
    3 detoxification of alcohol
    4 urea formation
    5 fat metabolism - fat conversion into fatty acids
    6 cholesterol production
    7 bile production
    8 vitamin storage
    9 plasma protein synthesis
    10 haemoglobin breakdown
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17
Q

how does detoxification of harmful substances occur?

how are toxins rendered less harmless?

what are some enzyme that render product less toxic ?

A

ethanol –> ethanal –> acetate + CoA

by oxidation, reduction and methylation process

CATALASE = Hydrogen peroxide into water and oxygen
CYTOCHROME P450 = breakdown drugs

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18
Q

how does detoxification of alcohol occur?

Study These Flashcards
A

ethanol –> ethanal –> ethanoic acid –> acetylCoA

19
Q

how is urine produced?
describe the 2 processes

Study These Flashcards
A

by DEAMINATION (liver) and ORNITHINE CYCLE (liver)

DEAMINATION:
- removal of the amino group
- ammonia + keto acid produced
-ammonia enters the ornithine cycle
-keto acid broken down into lipids and cholesterol

ORNITHINE CYCLE:
- process by which ammonia is rendered less toxic

ammonia + co2 –> CITRULINE + H2O –> CITRULINE + ammonia –> ARGININE + H2O –> ARGININE + H2O = urea.

20
Q

what is the kidney function?

Study These Flashcards
A

blood filtration

21
Q

kidney components

Study These Flashcards
A

capsule
renal cortex
medulla (has pyramids)
pelvis
nephrons
ureter
renal artery
renal vein

22
Q

what is the functional unit of kidney and does it do?

Study These Flashcards
A

NEPHRONS - filters blood and reabsorb useful material before eliminating it in urine

23
Q

nephrons structure

Study These Flashcards
A

glomerulus
proximal convulated tubule
distal convulated tubule
Loop of Henle
descending limb
ascending limb
collecting duct

24
Q

how does filtration occur?

Study These Flashcards
A

ultrafiltration
selective reabsorption
reabsorption of water
osmoregulation

25
what is the glomerulus function and describe it
ultrafiltration - blood enters the glomerulus from the afferent arteriole at high hydrostatic pressure, which causes small molecules (amino acids and ions) to be pushed out of the capillaries through fenestration present in the endothelium, in the Bowman's capsule.
26
what is the fluid created by the substances that are being pushed out?
BLOOD PLASMA / glomerular filtrate which contains: water amino acids vitamins and inorganic minerals
27
what is the barrier that enables filtration? what are the components?
the endothelium of the capillary - presence of fenestration which allows small molecules to pass out of the capillary the basement membrane - consist of a fine mesh of collagen fibres and glycoproteins, acts as a filter to prevent the passage of big molecules the epithelial cells of Bowman's capsule - podocytes (finger like projections called major processes on which minor processes can be found), projections ensures that there r gaps between cells.
28
where does selective reabsorption occur?
in the proximal and distal convulated tubule
29
what increases the efficiency of selective reabsorption of cells in PCT?
microvili of cells highly folded cotransport protein mithocondria walls of PCT are 1 cell thick to allow short diffusion distance
30
how does selective reabsorption occur?
Na+ ion are actively transported out of the epithelial cell into the capillary, this causes a concentration gradient between epithelial cell and tubule lumen. Due to this concentration gradient, Na+ diffuse in the epithelial cell via CO-TRANSPORT protein, Na+ enters the epithelial cell in addition to glucose and amino acids. Finally, glucose can diffuse from PCT to capillary and blood stream.
31
where does water reabsorption occur?
loop of Henle
32
how does reabsorption of water occur?
Na+ and Cl- are actively pumped out the ascending limb increasing the ions concentration in the tissue fluid and lowering the water potential. This causes water to diffuse out by osmosis from the descending limb Ions concentration in the limb decrease as we go down the loop.
33
what are the properties of the ascending and descending limb
descending limb = permeable to water and impermeable to ions ascending limb = impermeable to water and permeable to ions
34
what happens after the loop of henle process?
tissue fluid goes in the distal convulated tubule and here mineral ions adjusment occurs through active transport and then goes in the collecting duct.
35
what happens in the collecting duct?
osmoregulation
36
desscribe osmoregulation
is the regulation of water and salt level in the body
37
what is the kidney capable to do based on water concentration/demand in the body?
alter the permeability of the collecting duct so: less water demand --> less water conservation --> less permeable wall --> less reabsorption --> more urine produced and less concentrated
38
how is the permeability controlled ?
by the hormone ADH
39
how does ADH affect permeability of collecting duct?
by inserting more aquaporins into the membrane of the collecting duct. These aquaporins allow water to be reabsorbed into the capillaries. As a result the urine passed out increases in concentration Collecting duct cells contain vesicles, the membranes of which contain many aquaporins ADH molecules bind to receptor proteins, activating a signalling cascade that leads to the phosphorylation of the aquaporin molecules This activates the aquaporins, causing the vesicles to fuse with the luminal membranes of the collecting duct cells This increases the permeability of the membrane to water
40
describe the process of osmoregulation?
osmoreceptors detects changes in the water potential. if low water potential --> osmorecetors loose water and shrink --> detected by neurosecretory cell and causes their stimulation IN THE HYPOTHALAMUS --> causes release of ADH --> act on the collecting duct increasing its permeability to allow more reasorption of water
41
pregnancy test
urine passes through the reaction centre reaction site contains free antibodies with dye enzymes attaches hCG hormone from urine binds to free antibody with dye enzyme attached in the reaction centre free antibody which has formed a complex with hCG binds to fixed hCG in the test site free antibodies which have not formed a complex with hCG bind to fixed antibodies in the control site blue dye appears in the control and test sites, which shows positive result
42
what happens to ADH after its function?
ADH is ultra filtrates from blood since it s small molecule, Ash is not completely reabsorbed therefore is excreted in urine
43
longer loops of henle
- more water reabsorption form collecting duct - more Na+ and K+ pumped out of ascending limbs

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