BIOCHEM liver

Question 1

what is the liver made up of and what kind of organ is it?

Answer 1

largest internal organ made up of several lobes below diaphragm

Question 2

what kind of activities does the liver carry out and what important roles does it play in ?

Answer 2

metabolic activities so generates a lot of heat and has an important role is glucose + protein metabolism which is important for homeostasis ( maintenance of constant internal environment)

Question 3

what vessels is the liver supplied with and how does blood leave the liver?

Answer 3

supplied with 2 blood vessels:

hepatic portal vein(intestine)- supply blood with high conc of digested food products eg glucose+aminos

hepatic artery - supply oxygenated blood
blood leave:
hepatic vein- transports deoxygenated blood to vena cava

Question 4

what cells is liver made up of and what are the functions?

Answer 4

hepatocytes
microvilli-increases SA

prominent Golgi A- preparation of cellular products for secretion

rough ER- synthesis+ intercellular transport of proteins

glycogen/fat granules- as energy reserves

lots mitochondria- generate ATP for metabolic reactions

plasma membrane- numerous transport of proteins + insulin receptors

Question 5

what function units is lobe of liver composed of and describe structure of lobes?

Answer 5

lobules
-each lobe has pairs of columns of hepatocytes from central vein
- between 2 pairs are sinusoids
- each sinusoid serviced by branch of HPV, HA, branch bile duct

Question 6

what do sinusoids alternate with?

Answer 6

bile canalculi and they unite to make bile duct which takes away liver secretion bile

Question 7

what are other cells found in liver ?

Answer 7

kupffer cells - attached to walls of sinusoids
involved in breakdown of old red blood cells + ingestion of potentially harmful bacteria

Question 8

is there any localisation in the function of livers?

Answer 8

yes cells closest to portal capillaries most active in glucose regulation + ATP formation

meanwhile cells closest to central vein most active in fat synthesis,glycoslysis + drug metabolism

Question 9

what are the functions of the liver?

Answer 9

thousands of chemical reactions, food materials absorbed from digestive system go to the liver to be stored + converted in other forms needed by body at that time

Question 10

what are the reactions that take place in the liver?

Answer 10

1. regulation of blood glucose levels
2. protein metabolism
3. haemoglobin metabolism
4. fat metabolism
5. alcohol metabolism
6. drug metabolism

Question 11

what is carbohydrate metabolism and how is it an example of homeostasis ?

Answer 11

sugars eg glucose enter liver from gut by HPV ( has extremely variable sugar content). liver maintains glucose blood levels constant by converting excess glucose into glycogen and so glucose concentration drops
an example of homeostasis

Question 12

what is homeostasis?

Answer 12

physiological control systems maintain internal environment with restricted limits

Question 13

what are the factors that are controlled within the restricted limits?

Answer 13

-blood pH
- core body temp
- blood glucose conc
- water potential of blood

Question 14

why is homeostasis vital to maintain its factors?

Answer 14

stable core temp- gives optimum temp for enzyme activity so low temp not enough kinetic energy for optimum enzyme activity =+ too High denatures

stable blood pH- gives optimum pH for enzyme activity, extreme changes=denaturation

stable blood glucose- sufficient substrate for respiration which relates energy for metabolic processes in body

water potential of blood- within restricted limits

Question 15

what do the physiological control systems in homeostasis rely on?

Answer 15

negative feedback which restores systems to original levels

Question 16

how does negative feedback work?

Answer 16

deviations from norm result in corrective processes being stimulated to restore to norm

possession of separate mechanisms involving NF controls departures in different directions from original state giving greater degree of control

Question 17

what would happen if there was an increase in blood glucose and what organ is involved?

Answer 17

1. detected by pancreas beta cells secrete hormone insulin in bloodstream.
2. insulin attaches to specific receptors on surface of target cells (liver + muscle)
3. insulin increases permeability of target cells to glucose by stimulating specific channel proteins in membrane so glucose can enter reducing blood conc

insulin also activates enzymes in liver + muscle so glucose converted into glycogen (glycogenesis) excess glucose concerted into fat when that store is full

Question 18

what would insulin corrective mechanism cause blood glucose concentration to do and how is NF involved ?

Answer 18

causes BGC to decrease + inhibit insulin production by NF

Question 19

what happens if there is a decrease in blood glucose concentration and what would happen if there was a demand exhaustion eg starvation or marathon?

Answer 19

1. falls e.g fasting or exercise detected by ALPHA cells in pancreas -secretes hormone glucagon into blood
2. glucagon attaches to specific reports on surface of target cells of liver + activates enzymes
3. glycogen is hydrolysed to glucose (glycogenolysis)
4. glucose released into blood increasing BGC

if demand glucagon activates enzymes that convert glycerol+amino acids into glucose (glucogenesis) released into blood

Question 20

what would glucagon corrective mechanism cause BGC to do and how is NF involved?

Answer 20

cause BGC to increase to normal + inhibit glucagon secretion by NF

Question 21

when BGC becomes too low how does adrenaline work?

Answer 21

1.hormone released by adrenal glands

2. attaches to receptors on surface of target cells + activates enzymes too hydrolyse glycogen to glucose so glucose released into blood providing glucose to cells in respiration + increase BGC

Question 22

what activates enzymes in cell by second messenger system?

Answer 22

cyclin AMP CAMP which activates enzymes to make glycogen to glucose

Question 23

what are diabetes type 1 +2?

Answer 23

type1= when cells in pancreas responsible for inulin are destroyed (occurs in childhood known as juvenile onset diabetes

type 2= cells have few inulin receptors or receptors less sensitive in response to insulin so cells take up less glucose and convert less of it so BGC remains high ( occurs in adult life + long term= long term obesity)

Question 24

how do you manage t1 and t2 diabetes?

Answer 24

t1= insulin dependent so inject themselves daily insulin

t2= have hbd so don’t need to inject insulin some do and they just avoid foods that cause rapid surge in BG so eat complex carbs like starch that are slowly digested

Question 25

how are diabetes diagnosed by what test ?

Answer 25

glucose tolerance test 1. attend surgery after overnight fast 2. drink 75g glucose solution 3. remain at rest as movement increases respiration so consumes glucose 4. BGC measured reg next 2hr using test strips with IMMOBOLISED enzymes 5. enzymes make colour change proportional to glucose so conc read by colorimetry 6. diabetes only appear in urine when severe

Question 26

is the body able to directly store amino acids + what happens those that aren't needed immediately for protein metabolism or glucose formation?

Answer 26

can't directly store them + those that aren't needed immediately for protein synthesis or glucose formation undergo 2 phases transamination and deamination

Question 27

what is transamination and why does the body make them?

Answer 27

amino group from amino acid transferred to kept acid to make new amino acid. transamination way body makes amino acids lacking in diet (non-essential amino acids)

Question 28

what is deamination and how is ammonia removed what does it involve in which cycle?

Answer 28

deaminated in liver by enzymatic removal of amino group (NH2) from amino acid along with hydrogen to make ammonia Beto-acid made which enters respiratory pathway to release energy by glycolysis or krebs (depends on amino acid) ammonia highly toxic combines with CO2 in orthanine cycle to make urea which is soluble and transported in blood from liver to kidneys where excreted in urine

Question 29

how does haemoglobin metabolism work and what breaks down red blood cells ?

Answer 29

red blood cells lifespan 120 days after they are broken by macrophages in liver 1. haemoglobin released broken down into haem + globin 2. globin broken down into amino acids 3. iron removed from Haem + what remains makes green pigment BILIVERDIN which converted into BILURUBIN yellow component of bile 4. accumulation of Billurubin leads to yellowing of skin (jaundice)- indicates liver disease 5. iron can combine with plasma protein to make complex transferrin which is reused to make haemoglobin

Question 30

what is fat metabolism and how does it work how does it help if glucose is low?

Answer 30

1. liver converts carbs into fats and removes cholesterol from blood + synthesises it when needed to make steroid hormones 2. drugs (statins) reduce cholesterol levels in blood by slowing production of it by liver 3. if glucose is short supply liver can break down lipids to glycerol + fatty acids which the fatty acids enter krebs and glycerol converted into glucose

Question 31

what is cholesterol and why is it synthesised which source diety can you get it?

Answer 31

type of lipid and synthesised as it is the starting point for synthesis of other steroid molecules -major source of cholesterol is diet such dairy rich in cholesterol + fatty acids from which cholesterol can be synthesised

Question 32

how does liver synthesise cholesterol?

Answer 32

by exporting it to other cells which removes cholesterol from body by converting it to bile salts and putting into bile where can be eliminated in faeces

Question 33

does liver synthesise other lipoproteins and which?

Answer 33

yes ones involved in transporting cholesterol and other lipids throughout the body such as VLDL HDL LDL and chylomicrons

Question 34

what do lipoprotein molecules contain?

Answer 34

triglycerol, cholesterol, phospholipids and protein known as apolipoprotein which binds the lipids

Question 35

how are lipoproteins differentiated?

Answer 35

on density by on types of apolipoproteins they contains, degree of lipid in a lipoprotein affect its density so low density more lipid it contains relative to protein

Question 36

what is LDL and its role and how does VLDL convert to LDL? and is it bas or good

Answer 36

transports cholesterol to cells in body as VLDLS stripped of triglycerides become more dense so particles remodelled in liver and become LDL LDL delivered cholesterol to cells used in membranes and synthesis of steroid hormones bad as it contributed it to plaque which hard deposit that can clog arteries and make them less flexible

Question 37

what is HDL involved in and what is its role and how does it remove LDL?

Answer 37

revsere cholesterol transport - excess eliminated from body by liver so secretes it in bile or converts to bile salts - liver removes LDL + other lipoproteins from circulation excess cholesterol from cells Brought back by HDL to liber (reverse cholesterol transport? -HDL synthesised and secreted by liver and small intestine it travels in circulation and gathers cholesterol to return it to liver by various pathways good cholesterol as it helps remove LDL in arteries

Question 38

how is ethanol/alcohol soluble in both aqueous and lipid environments and what does this mean?

Answer 38

this is due to small size and alcoholic hydroxyl group which means they freely pass bodily fluids to cells since HPV passes from gut to liver so there is a bulk of ingested ethanol metabolised in the liver

Question 39

what type of processes is alcohol metabolised by and which enzymes what is their role?

Answer 39

-metabolised by lots processes/pathways most common involves 2 enzymes alcohol dehydrogenase ADH and aldehyde dehydorgenease ALDH these enzymes break apart the alcohol molecule making it possible to eliminate by body

Question 40

describe how alcohol metabolism works?

Answer 40

1. ADH metabolises alcohol into acetaldehyde which is highly toxic substance 2 NAD is reduced to make NADH +H which then enters mitochondria to be oxides to less active byproduct Acetate also needs NAD to be reduced 3 acetate then metabolised into H2O and CO2 for easy elimination

Question 41

what is alcohol related liver disease ARLD and what is it caused by and symptoms ?

Answer 41

liver damage caused by excessive alcohol intake and several stages and symptoms but won't cause any symptoms until liver is severely damage symptoms include feeling sick, weight loss, loss of apatite, jaundice, swelling in ankles and stomach, confusion or drowsiness and vomiting blood or in stools

Question 42

why doesn't liver regenerate if someone drinks too much?

Answer 42

the liver does each time it filters alcohol however liver cells die can make new cells but prolonged misuse reduces ability of regenerating (permanent damage)

Question 43

what is alcohol hepatitis and how is it caused what symptoms? what are the factors that influence it

Answer 43

inflammatory condition of excessive alcohol consumption over extend period of time when alcohol is processes liver makes highly toxic chemicals that injure liver cells that leads to inflammation and hepatitis doctors aren't sure how it actually develops as it develops in minority of heavy drinkers but also in moderate drinkers factors influencing: genetics how body processes alcohol and other liver disorders eg hepatitis C, malnutrition, concurrent consumption alcohol outside meal team women also twice greater risk due to how body processes alcohol

Question 44

what is cirrhosis how does it develop and what causes it?

Answer 44

scarring of liver caused by continuous long term liver damage eg by alcohol. scar tissue replaces heathy and prevents liver working properly, damage can't be reversed and will come to a point of liver failure is fatal if liver fails takes years ti get to that stage so can be treated to slow progression common causes- alcohol misuse over many years, infected hepatitis c virus for long time , NASH which causes excess fat to build in liver is most common due to obesity and decrease in physical activity less common causes : hepatitis b or inherited liver disease

Question 45

where does drug metabolism occur and how?

Answer 45

occurs in liver some in gut wall and lungs or blood plasm metabolic processes convert drugs into more water soluble compounds by increasing polarity before drugs can be excreted into bodily fluids such as urine/bile. only few drugs excreted without being metabolised first and once they are metabolised therapeutic effect goes

Question 46

what enzymes do liver hepatocytes contain for drug metabolism which group do they belong to and which organelle are they in?

Answer 46

cytochrome p450 group and housed in smooth er

Question 47

what is drug metabolism divided into and do all drugs undergo both?

Answer 47

2 phases and not all drugs undergo both some undergo only one of them

Question 48

what is phase 1 of drug metabolism?

Answer 48

1. reduction, hydrolysis of drug but most common biochemical process is oxidation 2. oxidation catalysed by cytochrome p450 enzymes + results in loss of electrons from drug 3. drug is then oxidised after phase 1 reactions drug metabolite still often chemically active 4. if metabolite of phase 1 is sufficiently water soluble in nature then can be readily excreted

Question 49

explain phase 2 of drug metabolism?

Answer 49

involves conjugation 1. conjugation of ionised group eg acetyl/methyl glutathione (metabolic processes occur in hepatocyte cytoplasm) 2. attachment of ionised group makes metabolite more water soluble which facilitates excretion + decreases pharmacological activity

Question 50

how is the drug aspirin metabolised?

Answer 50

by liver undergoes phase 1 hydrolysis so is then salicylic acid phase 2 its conjugated with glycine making range of ionised metabolites can be excreted into urine

Question 51

what are free radicals ?

Answer 51

atom or group off them has unpaired electron so outermost shell isn't full so will stabalise itself by losing electron to fill yo empty outermost shell or share with neighbouring atom looking to also do the same making weak bond free radical forms when weak bond is broken and uneven amount electrons so unpaired and chemically active wiki try and steal from another atom leaving its victim short an electron which will do the same and lead to free radical CASADE so enormous chain of them which quickly damages living tissue

Question 52

how are free radicals formed?

Answer 52

- normally during metabolism -external exposures ti x-ray, cig smoke,pollutants - immune system creates them to neutralise viruses + bacteria

Question 53

what are free radicals more suspecting to?

Answer 53

attack fats, DNA, RNA, cellular membranes, proteins, vitamins + carbs O2 is lethal too in aerobic oxygen free radicals implicated in overall aging process and responsible for aging cancer and inflammation in skin

Question 54

what are antioxidants how do they help against free radicals?

Answer 54

molecules safely interact and terminate chain reaction before vital molecules are damaged - neutralise them by donating electron of own and this doesn't effect antioxidants stable in either form so they act as scavengers helping prevent cell and tissue damage which may lead to cellular damage

Question 55

what are the most common antioxidants and how they help and which source?

Answer 55

vitE- most abundant fat soluble antioxidant in body, found in nuts, seeds, veg, fish oils and is MOST EFFICIENT IN CHAIN BREAKING VitC- most abundant water soluble antioxidant in body, found in citrus fruits and green veg COMBATS FREE RADICAL formation caused by pollution and cig smoke BETA-carotene present in liver, dairy products and fruit veg

Question 56

what antioxidants may prevent diseases?

Answer 56

heart disease= vet E protects against cardiovascular disease defends against LDL-oxidation and artery clogging plaque formation cancer=vit C intakes particularly mouth and oesophagus age-related eye disease-combo of c and E, beta carotene and zin offered some protection agains development of age related macular degernation in people who High risk

Question 57

what are vitamins?

Answer 57

group organic substances essential in small amounts for normal functions in body

Question 58

where is vitD found, function and what deficiency?

Answer 58

found in fish liver, oil, egg yolk, dairy produce, margarine and sunlight on skin function = calcium phosphorus absorption from gut indirect role in bone + tooth formation Deficiency = rickets- growing bones fail to calcify

Question 59

what is B1 found, function and deficiency?

Answer 59

wholemeal flour, wheat rice germ yeast, liver, kidney and heart. function= acts as COENZYMES IN DECARBOXYLASE ENZYMES in krebs deficiency= BERIBERI= nervous system affected, muscle weakness HEART FAILURE, REDUCED GROWTH

Question 60

where is vitC found, function and deficiency?

Answer 60

fresh fruits, green veg potato, tomato function= collagen biosynthesis+ connective tissue formation Deficiency= scurvy- bleeding gums, poor wound healing, anaemia HEART FAILIURE

Question 61

how do vitamins play a vital role in metabolic reactions?

Answer 61

act as cofactors/coenzymes in enzymic reactions

Question 62

where is VitA found why vital

Answer 62

fish oil, liver,milk carrots spinach and water cress vital in normal epithelial cell function + in synthesis of retinal used to form pigment rhospin present in rod cells in retina of eye Deficiency of vit A- dry skin, degen mucus membranes, poor night vision extreme case night blindness

Question 63

what is rickets caused by?

Answer 63

calcium deficiency, if dietary calcium low body metabolises skeletal calcium lack vita causes poor calcium utilisation in bone growth when calcium needs to be restored

Question 64

why phosphorus ion important,deficiency, food source?

Answer 64

importance=nucleic acids, Deficiency= muscle dysfunction + weakness food source= dairy

Question 65

potassium ion importance, deficiency food source

Answer 65

important= nervous conductance Deficiency= muscle weakness source=vegs

Question 66

sodium ion importance,deficiency,source

Answer 66

importance=nervous conductance Deficiency= sodium homeostasis vital to normal physiological function of cells source=table salts

Question 67

magnesium ion and calcium importance

Answer 67

importance- bone + tooth structure

Question 68

manganese importance

Answer 68

bone development

Question 69

iron importance and deficiency

Answer 69

heam group in haemoglobin myoglobin deficiency = anaemia

Question 70

copper importance

Answer 70

electron carriers

Question 71

fluorine importance

Answer 71

component of tooth + bone