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Excretion Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is excretion?

A

the removal of excess harmful metabolic waste from the body e.g bile, CO2

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2
Q

products that need to be excreted?

A

CO2
nitrogenous waste like urea
bile

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3
Q

what are the excretory organs

A

liver
kidney
skin
lungs

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4
Q

how is CO2 removed from the blood?

A

CO2 from surrounding tissues diffuses into red blood cells and reacts with water in presence of carbonic anhydrase to form carbonic acid. carbonic acid dissociates to form H+ and (HCO3- diffuses out of the cell to the alveoli to give out CO2.
CHARGE IN THE CELL IS MAINTAINED BY MOVEMENT OF Cl- IONS (CHLORIDE SHIFT)

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5
Q

what happens to the excess H+ ions?

A

the H+ ions increases the pH of the blood which affects quaternary structure of haemoglobin protein in the blood
H+ combines with haemoglobin to form haemoglobinic acid (haemoglobin acts as a buffer.

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6
Q

what happens to the remaining non transported carbon-dioxide?

A

reacts with haemoglobin to form carboaminohaemoglobin.

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7
Q

what are liver cells called?

A

hepatocytes

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8
Q

properties of liver as a good transport system

A

well vascularised for removal of metabolic waste
many mitochondria to produce ATP
cuboidal shape with lots of microvilli for efficient transport

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9
Q

types blood vessels found in the liver and their uses

A

hepatic artery- oxygenated blood from the heart to the liver through the aorta.
hepatic portal vein- deoxygenated blood from digestive system with products of digestion to the liver joins the vena cava
hepatic vein-detoxified blood and re-joins to vena cava
bile duct- carries bile from liver to gall bladder where it is stored.

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10
Q

what are inter-lobular vessels?

A

branches of arteries which run through the lobules.

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11
Q

what is the sinusoid?

A

a chamber which contains mixed blood from hepatic artery and vein

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12
Q

what are kupffer cells?

A

specialised macrophages in sinusoids which breakdown worn-out RBC

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13
Q

where is bile made?

A

liver

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14
Q

where is bile released?

A

bile canaliculus

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15
Q

where is each hepatic portal vein found

A

at the centre of each lobule

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16
Q

functions of the liver

A

bile synthesis
gluconeogenesis
storage of iron copper and soluble vitamins
location of ornithine cycle
detoxification of poison
synthesis of cholesterol from acetyl co-A
phagocytosis of worn out red blood cells
production of heparin and other plasma proteins

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17
Q

what is deamination?

A

process of removing the amino group from amino acids in the liver to produce ammonia

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18
Q

what does the ornithine cycle does?

A

series of enzyme catalysed reactions to convert ammonia into urea (less toxic)

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19
Q

process of ornithine cycle

A

ammonia reacts with CO2 to produce citrulline and water
citrulline reacts with ammonia to produce arginine and water
water is used to break down arginine to urea and ornithine.

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20
Q

what form does the liver store sugar?

A

in the form of glycogen

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21
Q

how is glycogen stored

A

compactly since it doesn’t affect water potential

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22
Q

what is glycogenosis?

A

the process by which excess sugar is converted into glycogen in the presence of insulin

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23
Q

what is gluconeogenesis?

A

process by which biological molecules e.g lipids are converted to glucose when blood sugar level is low and there is no glycogen

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24
Q

enzymes found in the liver and function

A

catalyse- catalyses breakdown of H2O2 to H2O and O2
cytochrome P450 which breaks down drugs e.g. cocaine
helps in electron transport in respiration.

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25
Q

where is alcohol broken down

A

hepatocyte

26
Q

process of alcohol detoxification?

A

broken down in presence of ethanol dehydogenase to make ethanal. (H atoms combine with NAD to form NADH)
ethanal is dehydrogenated in presence of ethanal dehydrogenase to form ethanoate (acetate)
acetate combines with coenzyme A to form acetyl co-A
acetyl co-A enters mitochondria for respiration.

27
Q

what is the function of ADH?

A

hormone that controls the permeability of the collecting ducts

28
Q

what are osmoreceptors?

A

sensory receptors that detects changes in water potential in the blood.

29
Q

what is osmoregulation?

A

control of water potential in the body.

30
Q

use of the hypothalamus?

A

the part of the brain which controls release of hormones from pituitary gland

31
Q

explain the process that occurs in the hypothalamus when there’s low water potential in the blood.

A

osmoreceptors in the hypothalamus detect low changes in blood water potential.
water moves by osmosis to blood from osmoreceptors causing it to shrink which stimulates neurosecretory cells in the hypothalamus to produce ADH.
a never impulse is sent down the neurosecretory cell to the posterior lobe of the pituitary gland.
ADH is secreted from the neurone onto the blood flowing through the pituitary gland.

32
Q

what cells produce ADH

A

Neurosecretory cells

33
Q

what happens in the collecting duct?

A

ADH travels along the axon of specialised nerve cells in the blood to the kidney.
• ADH binds on complementary receptors found on the plasma membrane of collecting duct cells.
• This causes a cascade of enzyme-controlled reactions which makes vesicles containing water permeable channels (aquaporins) to move towards the plasma membrane near the lumen side of the collecting duct.
• The aquaporins vesicles fuse with the plasma membrane and water diffuses from the lumen into the cytoplasm of the cells. This means the collecting ducts are now more permeable (more osmosis and less urine passes out of the body).
• If ADH secretion stops, then ADH no longer binds to receptors, the water permeable channels are removed as the plasma membrane folds inwards and less water reabsorption occurs, and more urine is produced.

34
Q

what is the half life of ADH

A

24mins

35
Q

what happens to ADH after it’s used?

A

it circulates to the liver through extracellular fluid space where it is broken down (it is a protein)

36
Q

what is ultrafiltration?

A

filtration of the blood at a molecular level under pressure.

37
Q

Where is the kidney found?

A

back of abdomen

38
Q

state the kidney regions and uses

A

cortex- ultrafiltration is carried out.
medulla- selective reabsorption is carried out
pelvis- transports urine to the ureter

39
Q

state the function of the nephron

A
  1. Ultrafiltration
  2. Selective reabsorption in the proximal convoluted tubule.
  3. Reabsorption of water in the loop of Henle.
  4. Reabsorption in the distal convoluted tubule an in the collecting duct.
40
Q

how does oxygenated blood enter the kidney?

A

renal artery

41
Q

what does the glomerulus consists of?

A

a knot of branches of arterioles

42
Q

uses of afferent and efferent arteriole

A

carries blood to the glomerulus

carries blood from glomerulus to other capillaries surrounding the rest of the cell

43
Q

what are the layers of the filter separating the lumen of the bowman’s capsule and the blood in the capillary

A
  • endothelium of capillary
  • basement membrane
  • the podocytes
44
Q

structure of endothelium of capillary and uses

A

narrow gaps-allow blood plasma and dissolved substances to pass out of capillary.
endothelium cells have pores called fenestrations

45
Q

structure and use of basement membrane

A

collagen fibre and glycoprotein mesh

-acts as filter for molecules with RMM less than 69000

46
Q

structure and function of podocytes

A

specialised cell on epithelial of bowman’s capsule
major and minor (finger-like projections which ensure that there are gaps between cells for blood fluid to pass through lumen of bowman’s capsule.

47
Q

describe process of filtration in glomerulus

A

high pressure is maintained because afferent is wider than efferent.
hydrostatic pressure is built up forcing substances endothelial pres across basement membrane to the bowman’s capsule.

48
Q

what is the fluid in the renal capsule called?

A

glomerular filtrate

49
Q

adaptations of walls of proximal convoluted tubule for selective reabsorption

A
  • Cuboidal epithelium cells with microvilli for large surface area for absorption.
  • The membrane also contains co-transporter proteins that transport molecules from the lumen of the tubule to the cell membrane (facilitated diffusion).
  • Outer membrane of the wall of tubule is folded with blood capillaries close by
  • Outer membrane contains sodium and potassium pumps.
  • Presence of many mitochondria because lots of absorption takes place.
50
Q

explain the process of reabsorption

A
  1. The Sodium-Potassium pumps, situated in the outer membranes of cells in the wall of the proximal convoluted tubule, actively transport sodium ions out of cytoplasm.
  2. This reduces the concentration of sodium inside the cells.
  3. So sodium ions will then diffuse down a concentration gradient back into the cytoplasm, by passing through co-transporter proteins and in doing so transport glucose or amino acids with them(facilitated diffusion)
  4. This causes the glucose and amino acid concentration to rise inside the cell which the leads to diffusion of these substances out of the outer membrane into the tissue fluid
  5. From the tissue fluid they diffusion into the surrounding blood capillaries and are carried away.
51
Q

structure of loop of henle’s

A

ascending (medulla)

descending (cortex)

52
Q

what happens in the ascending limb?

A
  • Water cannot leave the tubule because impermeable.
  • Na and Cl ions diffuse out of the lower part of the ascending limb
  • Then, higher up the ascending limb, Na and Cl ions are actively transported out.
  • This means that a higher water potential (less negative) is created since the fluid is losing salts and not water.
53
Q

describe the reabsorption that takes place in the distal convoluted tubule

A
  • So now we have the “dilute fluid” which passes through the distal convoluted tubule
  • The distal convoluted tubule is much shorter than the proximal.
  • It is here that active transport is used to adjust various mineral concentrations (EG: urea actively transported into tubule here)
  • Then the fluid, still with a high water potential, continues into the collecting tube
54
Q

describe the reabsorption process in the collecting duct

A

• The purpose of the collecting duct is to carry the diluted urine into the deep medullary tissue towards the renal pelvis where there is a very low water potential.
As it descends deeper into the medulla water moves by osmosis out of the duct into the surrounding tissue fluid (where it then enters the blood capillaries). The permeability of the collecting ducts affects how much water is reabsorbed.
• This creates a more concentrated urine concentration.
• Formation of a concentrated urine will occur in response to the release of ADH which regulates water potential

55
Q

what is glomerular filtration rate?

A

rate at which fluid enters nephrons over time (per minute)

56
Q

what is monoclonal antibodies?

A

antibodies made from one type of cell- specific to one type of molecule.

57
Q

what is renal dialysis

A

mechanism used to artificially regulate concentration of solutes in the blood.

58
Q

what are causes of kidney failure?

A 
diabetes mellitus
heart disease
hypertension and infection
high blood pressure 
knock during contact sport 
kidney stone
could be congenital
59
Q

how does diabetes cause kidney failure?

A

causes damage in kidney blood vessels.
this destroys filters and causes waste products to build up.
filter starts to leak out proteins.

60
Q

symptoms of kidney failure

A

reduction in urine volume oedema

cloudy or bloody urine

61
Q

how does GFR determine good kidney function

A

GFR calculated from serum creatinine levels

low GFR = less effective kidney

biology (11 decks)

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