5.1.2 Excretion (Finish)

Question 1

What is excretion?

Answer 1

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

Question 2

what are three examples of metabolic waste products

Answer 2

Carbon dioxide
Urea
Bile pigments

Question 3

what are the individual liver cells knowns as?

Answer 3

hepatocytes

Question 4

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

Answer 4

lobules

Question 5

what in in the core of each lobule

Answer 5

central vein

Question 6

how do liver cells regenaerate when damaged?

Answer 6

Mitosis

Question 7

what are the three vessels in the liver?

Answer 7

hepatic artery
hepatic portal vein
hepatic vein

Question 8

what is the hepatic artery?

Answer 8

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

Question 9

what is the hepatic portal vein?

Answer 9

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

Question 10

what is the hepatic vein?

Answer 10

branches into the inferior vena cava
takes deoxygenated blood

Question 11

ratio of blood between hepatic artery : hepatic portal vein

Answer 11

25% hepatic artery : 75% hepatic portal vein

Question 12

where do the two blood supplies from the liver meet?

Answer 12

at the sinusoids

Question 13

what are the function of the sinusoids?

Answer 13

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

Question 14

what are the walls of the sinusoids made up of?

Answer 14

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

Question 15

what are kupffer cells?

Answer 15

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

Question 16

why are sinusoid NOT considered capillaries?

Answer 16

they do not have walls made of endothelium tissue.]

Question 17

where does blood from the sinusoids drain into?

Answer 17

The central vein

Question 18

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

Answer 18

the hepatic vein

Question 19

what vessel does blood leave the liver?

Answer 19

the hepatic vein, joining the inferior vena cava

Question 20

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

Answer 20

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

Question 21

what is bile, and what is its roles?

Answer 21

what:
alkaline fluid

function:
emulsify lipids into smaller droplets
neutralise stomach acid

Question 22

what are the three basic functions of the liver?

Answer 22

storage of glycogen
detoxification
formation of urea via the ornithine cycle

Question 23

what are the functions of the liver related to?

Answer 23

homeostasis

Question 24

How does glycogen strorage work?

Answer 24

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

Question 25

how are hepatocytes affected by insuin?

Answer 25

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

Question 26

how are hepatocytes affected by glucagon?

Answer 26

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)

Question 27

What does adrenaline with the storage of glycogen?

Answer 27

mimics the effect of glucagon

Question 28

what is detoxification?

Answer 28

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

Question 29

suggest two examples of detoxification

Answer 29

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

Question 30

Describe the breakdown of hydrogen peroxide into water and oxygen

Answer 30

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

Question 31

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

Answer 31

oxidation of ethanol inside the cytoplasm of hepatocytes ethanol + [O} ----\> Ethanal Ethanal + [O] ------\> Ethanoic acid

Question 32

How is urea formed?

Answer 32

via the orthanie cycle

Question 33

how are process from one protein to another?

Answer 33

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

Question 34

what happens to excess amino acids?

Answer 34

INSIDE LIVER: Transamination Deamniation

Question 35

what is transamination? Why is it useful?

Answer 35

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

Question 36

what is deamination?

Answer 36

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

Question 37

Draw out the ornathine cycle

Answer 37

Question 38

describe the 3 steps of the orthanince cycle

Answer 38

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.

Question 39

is the ornathine cycle passive or active?

Answer 39

Active, it requires ATP

Question 40

What is the main function of the kidneys?

Answer 40

filtering the blood producing urine (urea and water) osmoregulation

Question 41

label this kidney

Answer 41

Question 42

How does one remember the order of the kidney strucutre?

Answer 42

Its in alphabetical order. capsule cortex medulla ureter

Question 43

label this nephron

Answer 43

Question 44

what is a nephron

Answer 44

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

Question 45

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

Answer 45

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

Question 46

what is the glomerulus?

Answer 46

tangle of capillaries in the bowman's capsule

Question 47

what is the proximal convoluted tubule (PCT)?

Answer 47

cortex selective reabsorption of glucose, salt ions etc back into the blood of an adjoining capillary Most of the water is reabsorbed here.

Question 48

what is the Loop of Henle?

Answer 48

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

Question 49

what is the Distal convoluted tubule (DCT)?

Answer 49

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)

Question 50

What is the collecting duct?

Answer 50

takes fluid from the DCTs of multiple nephrons cortex-\>medulla-\>pelvis sensitive to ADH, hence in determining the final concentration of urine produced

Question 51

what is the hydrostatic pressure like in the blood vessels?

Answer 51

very high hydrostatic pressure

Question 52

what is the order of ultrafilration?

Answer 52

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

Question 53

what is the blood leaving the kidneys like?

Answer 53

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

Question 54

what are the main three functions of the kidney?

Answer 54

ultrafiltration; selective reabsorption; production of urine