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MPW biology > 5.1.2 Excretion (Finish) > Flashcards

5.1.2 Excretion (Finish) Flashcards

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1
Q

What is excretion?

A

Excretion is the removal of metabolic waste from a cell or from the body.

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2
Q

what are three examples of metabolic waste products

A

Carbon dioxide
Urea
Bile pigments

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3
Q

what are the individual liver cells knowns as?

A

hepatocytes

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4
Q

what is it called when Hepatocytes are grouped into dense structures?

A

lobules

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5
Q

what in in the core of each lobule

A

central vein

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6
Q

how do liver cells regenaerate when damaged?

A

Mitosis

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7
Q

what are the three vessels in the liver?

A

hepatic artery
hepatic portal vein
hepatic vein

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8
Q

what is the hepatic artery?

A

branch from the aorta
brings oxygenated blood (for areobic respiration)

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9
Q

what is the hepatic portal vein?

A

Comes from the small intenstine
blood rich in the products of digestion (glucose, amino acids etc)

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10
Q

what is the hepatic vein?

A

branches into the inferior vena cava
takes deoxygenated blood

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11
Q

ratio of blood between hepatic artery : hepatic portal vein

A

25% hepatic artery : 75% hepatic portal vein

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12
Q

where do the two blood supplies from the liver meet?

A

at the sinusoids

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13
Q

what are the function of the sinusoids?

A

carry blood through the liver tissue in close contact with hepatocytes.

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14
Q

what are the walls of the sinusoids made up of?

A

The walls of sinusoids are made up of the hepatocytes themselves, plus some Kupffer cells

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15
Q

what are kupffer cells?

A

essentially macrophages
held in a fixed position as part of the sinusoid wall
capable of phagocytosis, removing pathogens from the blood

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16
Q

why are sinusoid NOT considered capillaries?

A

they do not have walls made of endothelium tissue.]

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17
Q

where does blood from the sinusoids drain into?

A

The central vein

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18
Q

what do all of central veins of all lobules eventually merge with?

A

the hepatic vein

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19
Q

what vessel does blood leave the liver?

A

the hepatic vein, joining the inferior vena cava

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20
Q

how do the hepatocytes produce and secrete bile? 6 steps.

A

hepatocytes secrete bile
bile canaliculi (tube)
bile ductiles (wider vessels)
ball gladder (storage)
bile duct
small intestine

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21
Q

what is bile, and what is its roles?

A

what:
alkaline fluid

function:
emulsify lipids into smaller droplets
neutralise stomach acid

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22
Q

what are the three basic functions of the liver?

A

storage of glycogen
detoxification
formation of urea via the ornithine cycle

23
Q

what are the functions of the liver related to?

A

homeostasis

24
Q

How does glycogen strorage work?

A

Hepatocytes are a store of glycogen
Glycogen is insoluble
branched structure ∴ easily hydrolysed (glycogenolysis)

25
Q

how are hepatocytes affected by insuin?

A

RESPONSE TO HIGH BLOOD SUGAR
insulin released by β‐cells in the pancreas
hepatocytes to increase their uptake of glucose
increased conversion of glucose to glycogen (glycogenesis)
increased respiration rate
these actions bring the blood sugar level down

26
Q

how are hepatocytes affected by glucagon?

A

RESPONSE TO LOW BLOOD SUGAR
Glucagon released by α‐cells in the pancreas
hepatocytes to decrease their uptake of glucose
increase hydrolysis of their stored glycogen to glucose (glycogenolysis)
hepatocytes to release this glucose into the blood
these actions bring the blood sugar level up

Extra: gluconeogenesis - produce more glucose from non‐carbohydrates (amino acids or fatty acids)

27
Q

What does adrenaline with the storage of glycogen?

A

mimics the effect of glucagon

28
Q

what is detoxification?

A

The removal of toxins from the blood and their breakdown or conversion into less harmful products

29
Q

suggest two examples of detoxification

A

Breakdown of hydrogen peroxide into water and oxygen
Conversion of ingested alcohol (ethanol) into less harmful ethanal

30
Q

Describe the breakdown of hydrogen peroxide into water and oxygen

A

hydrogen peroxide —–> water and oxygen
catalase enzyme
inside the membrane-bound organelles (similar to lysosomes) called peroxisomes

31
Q

Describe the conversion of ingested alcohol (ethanol) into less harmful ethanal. Learn image.

A

oxidation of ethanol

inside the cytoplasm of hepatocytes

ethanol + [O} —-> Ethanal

Ethanal + [O] ——> Ethanoic acid

32
Q

How is urea formed?

A

via the orthanie cycle

33
Q

how are process from one protein to another?

A

proteins are digested by protease enzymes in the stomach and small intestine

absorbed into the blood

Body cells absorb amino acids from the blood for use in translation

34
Q

what happens to excess amino acids?

A

INSIDE LIVER:

Transamination

Deamniation

35
Q

what is transamination? Why is it useful?

A

what:

one type of amino acid (excess) converted into a different type of amino acid

why useful:

realtive proportions of 20 amino acids from diet do not match the proportions needed for protein synthesis

36
Q

what is deamination?

A

the amine (NH2) group of the amino acid is removed

amine group - converted to to ammonia (orthanie cycle)

carbon skeleton - converted to pyruvate or fatty acid

37
Q

Draw out the ornathine cycle

A
38
Q

describe the 3 steps of the orthanince cycle

A
  1. Ammonia and carbon dioxide combine with an acceptor molecule, ornithine, producing an intermediate called citrulline;
  2. Citrulline combines with a further ammonia molecule, producing arginine;
  3. Arginine is split into urea (which leaves the cycle) plus ornithine: since the acceptor molecule ornithine is regenerated, the cycle can continue and more ammonia can be converted to urea.
39
Q

is the ornathine cycle passive or active?

A

Active, it requires ATP

40
Q

What is the main function of the kidneys?

A

filtering the blood

producing urine (urea and water)

osmoregulation

41
Q

label this kidney

A
42
Q

How does one remember the order of the kidney strucutre?

A

Its in alphabetical order.

capsule

cortex

medulla

ureter

43
Q

label this nephron

A
44
Q

what is a nephron

A

the tubules which make up the main functional strucutres of the kidneys.

45
Q

what is the bowman’s capsule? what is its function?

A

cup‐like structure

in the cortex

start of a nephron

contains the glomerulus

the site of ultrafiltration of the blood, since water and small solutes are pushed out of the blood into the Bowman’s capsule

46
Q

what is the glomerulus?

A

tangle of capillaries in the bowman’s capsule

47
Q

what is the proximal convoluted tubule (PCT)?

A

cortex

selective reabsorption of glucose, salt ions etc back into the blood of
an adjoining capillary

Most of the water is reabsorbed here.

48
Q

what is the Loop of Henle?

A

elongated hairpin‐shaped section of the nephron

descending limb and ascending limb

creates a very high solute concentration in the tissue fluid of the medulla, to increase reabsorption of water

allows for more concentrated urine

49
Q

what is the Distal convoluted tubule (DCT)?

A

cortex

permeability of its walls to water depends on ADH (anti‐diuretic hormone) concentration

role:

finetuning the extent of water reabsorption

selective reabsorption of ions including H (conctrolling blood pH)

50
Q

What is the collecting duct?

A

takes fluid from the DCTs of multiple nephrons

cortex->medulla->pelvis

sensitive to ADH, hence in determining the final concentration of urine produced

51
Q

what is the hydrostatic pressure like in the blood vessels?

A

very high hydrostatic pressure

52
Q

what is the order of ultrafilration?

A

afferent arteriole brings blood to glomerulus (from renal artery)

very high hydrostatic pressure

water plus small solutes forced through the permeable walls of the glomerular capillaries into the bowman’s capsule

——————————————————————————————————–Blood leaves the glomerulus via efferent arteriole (narrower lumen thyan afferent arteriole to maintain high hydrostatic pressure)

efferent arteriole branches into a network of capillaries (around the PCT, loop of Henle and DCT)

^Allows for the reabsorbtion of water and small solutes^

capillaries merge into venules which converge into the renal vein to heart

53
Q

what is the blood leaving the kidneys like?

A

very low urea concentration

concentrations of glucose and amino acids that are (almost) as high as in the blood that entered the kidney

salt ion concentration and water potential that should have been corrected to optimal levels

54
Q

what are the main three functions of the kidney?

A

ultrafiltration;
selective reabsorption;
production of urine

MPW biology (26 decks)

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