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Biological Sciences > Liver > Flashcards

Liver Flashcards

1
Q

What are the main properties of the liver

A

. Second largest organ in the human body ( after skin )
. Make up 2-3% body mass = heavy and large organ ( 3 pounds)
.It accounts for 20-30% of the total oxygen consumption-very metabolically active
. Filters 1.4L blood every minute

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2
Q

How many lobes does liver have

A

2
(Ieft and right)
Although if you lift liver, look from back = 4 lobes ( 2 smaller lobes = cordate lobe and quadrant lobe = but most are 2 main lobes

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3
Q

Where is liver located

A

Below diaphgram

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4
Q

What is a liver a place of

A

Where old rbc’s are broken down.

Each rbc has life span of 110 days - after, body breaks them down and processes them

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5
Q

What is role of phagocytic cells in liver

A

Recruit dysfunctional rbc’s from circulation - breaking them down

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6
Q

Why is detoxification and elimination of toxic substances important in liver

A
  • Make sure everything coming from digestive tract isnt infected as primary source of infection is what we injest and take in, gut is full of bacteria - dont want in systemic circulation
  • Bacteria taken in through diet, waste products generated through food consumption, toxins produced, natural drugs, prescription medication long term = liver failure
    SO IMMUNE SURVEILLANCE CELLS IN LIVER KEEP US CLEAN
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7
Q

What are the main functions of the liver

A

. Metabolism
. Uptake of nutrients delivered from the digestive tract via portal vein
- Temporary nutrient storage ( glucose-glycogen). Synthesis, storage, interconversion, and degradation of metabolites ( nutrients taken in )
- The regulated supply of energy - rich intermediates and building blocks for biosynthetic reactions
. Vitamin storage ( maintains Fe reserve )
. Produces coagulation factors
. Detoxification - removal of toxins from blood/toxic substances - excretion of substance with bile, urine, faeces
.Bile production -from breakdown of rbc’s - produce bile salts - digestion of lipids
. Kupffer cells ( macrophages ) - lining vessels of liver

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8
Q

What does liver do

A

Maintains the bodies chemical and metabolic homeostasis - keeps everything at ultimate level

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9
Q

What are coagulation factors

A

Proteins continuously flowing around blood plasma ready to form clots when injury = dont bleed to death

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10
Q

Why have a mineral and vitamin storage

A

Just incase go through starvation period = reserves
Due to continous flow in of molecules - factory -turn them into other building blocks of life - make new amino acids,sugars and cholestrol - pumped out into blood to other cells

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11
Q

What are most of the toxins

A

Lipid based - so 1st turn them into water loving molecule = changes properties of molecule

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12
Q

What is the main mineral liver store

A

Iron

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13
Q

What are the main exit routes for excretion of substances

A
  • Bile
  • Urine
  • Stools - faeces
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14
Q

What are the 2 lobes in the liver separated by

A

Falciform ligament- separates the lobes and holds liver in place suspended below diaphragm - holds them apart from each other, makes connections with diaphgram

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15
Q

What does each lobe contain

A

Lobule

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16
Q

What is a lobule

A

Little hexagonal structures composed of blood vessel , bile canaliculi , blood vessels come together to form sinusoid

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17
Q

What are lobules comprised of

A

Hepatocytes which are specialised cells and surrounded by reticular fibre. Main cells in liver

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18
Q

What else is found in the liver

A
  • Connective tissue support - thin connvective tissue capsule
  • Interlobual spaces - support blood vessels and bile ducts
  • Reticular fibres - collagen III - lots of proteoglycan ( flexibility - space out collagen fibres as water loving ) - around hepatocytes
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19
Q

Where do lobes sit

A

Below diaphgram

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20
Q

Why are livers large and heavy

A

Don’t want it slumping down onto gut otherwise its force all stool out of you - suspended in place

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21
Q

Where does blood come in and out in the liver

A

Blood in through portal vein and Hepatic artery

Blood out through Central Vein

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22
Q

Where do blood from portal vein and hepatic artery mix

A

In hepatic sinusoids

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23
Q

What is bile secreted by and where does it leave

A

Through bile ducts
Bile flowing in opposite direction. Hepatocytes secrete bile fluid and runs back towards corner points and exits through bile ducts

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24
Q

What is role of hepatocytes

A

Take up nutrients and healthy O2 supply

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25
Q

What does liver need

A

Healthy supply of blood

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26
Q

What is the process of dual blood supply into liver

A
  1. Oxygen rich blood flows from the hepatic artery from the aorta - need about 30/40% O2
  2. Nutrient rich oxygen poor blood from portal vein that comes from digestive system
    These flow past hepatocytes
    HEPATIC ARTERY - O2 BLOOD
    PORTAL VEIN - NUTRIENT RICH BLOOD
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27
Q

What is the hepatic artery

A

Direct branch off the abdominal aorta

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28
Q

What shape is lobule

A

Hexagonal

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29
Q

What colour is liver and why

A

Dark brown
Due to high density of blood vessels surrounding it
When blood mixes = hepatocytes are red and produces bile which runs opposite direction back out corner of lobule

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30
Q

Structure of hepatocytes

A
  • Run through each liver lobule and sinusoids and exit out through central vein
  • Have direct surface opposing blood vessel directly = lots of capillaries though
  • Microvilli to increase surface area
  • Adjacent hepatocyte cells have tight junctions to prevent fluid flowing between hepatocytes
  • Bile canaliculi run between hepatocytes
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31
Q

What does each lobule have

A

Incoming portal vein and hepatic artery at each corner of hexagon - flow inwards

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32
Q

What runs through middle of each lobule and what happens here

A

Central vein

Blood exits here

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33
Q

What is at each corner of hexagon that makes up lobule and what does it form

A 
Blood vessels 
Portal vein
Bile duct
Hepatic artery
TOGETHER forms PORTAL TRIAD - 6 per lobule, 1 in each corner, shared with lobuls next to it.
34
Q

Structure of hepatic sunusoids

A
  • They are blood vessels made up of endothelial cells

- They are fenestrated - allow easy flow of plasma but not erythrocytes

35
Q

What separates hepatocytes and hepatic sinusoids ?

A

Vasculature Disse’s space

36
Q

What’s Disse’s space ?

A

Separates hepatocytes and hepatic sinusoid and contain plasma and dendritic cells

37
Q

Function of dendritic cells

A
  • Immune cells - sit it in Disse’s space
  • Activate rest of immune system
  • Detect if anything in there that could indicate infection in there
  • Send out chemical messengers - recruit rest of immune system starting with neutrophils and lymphocytes later
38
Q

Function of kupfer cells

A
  • Perform phagocytic function to remove protein complexes and small particles from the blood
  • They also perform immune surveillance against toxic material from the gut and pathogens from the intestinal flora
  • Immune cells which are inside of synocoids
39
Q

Carbohydrate metabolism in liver

A
  • Store excess glucose as glycogen ( glycogenesis )
  • Break down of glycogen to glucose ( glycogenolysis )
  • Convert galactose and fructose to useable glucose
  • Gluconeogenesis - formation of glucose from other molecules ( non carbs ) i.e. use keto acids
40
Q

What is liver main place for

A

Where you can store xs carbs, xs glucose in form of glycogen

41
Q

What happens during glycogenolysis and glycogenesis

A

Glycogenesis - xs sugar detected in systemic circulation, taken out and stored as glycogen in liver, under chemical signal of insulin
Glycogenolysis - low levels of blood glucose can send signal to release glucagon = breakdown of glycogen to glucose = increase glucose in systemic circulation

42
Q

What is the glucose buffer

A
  1. high blood glucose level - liver - glycogen formation - normal blood glucose
  2. fall in blood glucose level - liver - glycogenolysis - normal blood glucose
43
Q

Function of glucose buffer

A

Regulates amount of free floating glucose in body

44
Q

Why do you need to regulate amount of glucose in body

A

Any change in systemic blood glucose levels = toxicity of cells around body = diabetes - misregulation of blood glucose levels

45
Q

What happens when high glucose levels in blood

A

Endothelial cells dysfunction = microvascular diseases e.g. diabetic retinography - leaking blood vessels in retina.
Also direct effect on neurons in body, high glucose levels can kill off neuron - scotomas in vision as you kill of retinal ganglion cells

46
Q

Why do we need glucose

A
  • Brain uses glucose as main energy source - as it doesnt have capacity to do gluconeogenesis itself
  • Red blood cells rely on glucose as their only energy source - cant produce glucose themselves as glucose is the only energy source
47
Q

How much reserves of glucose is there in glycogen stores and what is the daily requirment

A
  • Glucose reserve of 190 g in glycogen store

- Need 160 g glucose to function = depleted all glucose reserves

48
Q

What does gluconeogenesis ensure

A
  • Helps maintain systemic glucose level in liver so brain and muscles have sufficient supply to meet demand
  • Provides an alternative pathway to produce glucose from carbon skeletons to keep brain going when demand exceeds glucose stores
    Substrates can be amino acids, glycerol, lactate
    i.e Amino acids - keto acids - glycerol
49
Q

What is process of triglyceride breakdown

A

triglyceride + water ———-> 3 fatty acid + glycerol
fatty acid - beta-oxidationto produce ATP - for metabolism
glycerol - gluconeogenesis to produce glucose - by producing C skeleton
Triglyceride separates fatty acid chain from glycerol

50
Q

Process of lipid metabolism in the liver

A

. Anabolism : turn lipids into other things to build storage structures
- synthesis of cholesterol ( in liver from lipids ) and fatty acids
- synthesis of lipids from carbohydrates and amino acids ( lipogenesis )
. Catabolism - beta oxidation of fatty acids to produce ATP

51
Q

What is lipogenesis

A

Take xs glucose and turn it into fatty acids stores through lipogenesis

52
Q

Process of protein metabolism in liver

A
  • Liver is the primary site of deamination of amino acids - oxidative deamination = produce NH3, urea cycle in liver, urea out into blood
  • Ammonia is turned into urea through urea cycle
  • Interconversion of amino acids ( transamination )
  • Site of plasma protein synthesis
53
Q

What vitamins does liver store

A 
. vitamin A ( 10 month store )
. vitamin D  ( 4 month store )
. vitamin B12  ( 1 year store )
. vitamin E and K
. Folate
54
Q

What is main mineral stored in liver

A

Iron

55
Q

How is iron stored in liver

A
  • Iron stored as part of the molecule ferritin in the liver

- Iron in blood bound transferrin - binds with apoferritin in liver to form ferritin .

56
Q

What happens when blood iron levels fall

A

Ferritin releases free iron to bind to transferrin in blood

57
Q

Where does most VitD come from

A

Activation of molecules after UV exposure - summer - enough to keep going in winter = good supplement to take in winter

58
Q

What is VitA essential for

A

Vision and a lot of processes

So have capacity to store for long time in case theres deficiencies in diet

59
Q

What is Vit B12 a source of

A

Meat - not in plant

If low in B12 - skin conditions e.g. eczema

60
Q

What can VitA act as

A

Mutagen
During development - if very high levels of vitA -interrupts with lot of signalling pathways required for formation of limbs/proper head
So when pregnant - dont eat liver due to it having high levels of vitA - shouldn’t be consuming any xs during gestation of fetus - mutation in baby and stop taking multivitamins when pregnant

61
Q

What coagulation factors does the liver produce ?

A
  1. factor 10
  2. factor 9
  3. factor 7
  4. fibrinogen
  5. prothrombin
62
Q

Why are factor 10,9 and 7 important

A

Activation proteins that activate clotting
Factor 10 also involved in inactivation of other parts of immune system - directly kill of pathogens from pore in cell surface of bacteria and kill it or act as signalling molecule - bind to protein secreted by pathogen

63
Q

Why are fibrinogen and prothrombin important

A

Clotting process in wound heeling due to inflammation

64
Q

What is coagulation factor

A

Protein free floating in blood, activated through different pathways

65
Q

What happens during liver detoxification

A

Hepatocytes convert toxins into non-toxic metabolites which can be excreted from the body

66
Q

What toxins do our bodies deal with each day

A
  • Breakdown products from hormones and neurotransmitters
  • Drug
  • Pollutants
  • Insecticides and pesticides
    These pass across, enter blood stream and filtered out by liver
67
Q

What are the 2 primary classes of chemical compound ( toxin )

A
  1. hydrophilic ( dissolves in water ) polar : can be excretes in bile or urine - easy to get rid of, liver doesnt have to do much
  2. lipophilic ( dissolves in lipids ) non-polar : must be converted to hydrophilic to be excreted by bile, urine or stool
68
Q

What is liver detoxication performed by

A

Hepatocytes

69
Q

What are the two phases of converting lipophilic into hydrophilic ?

A

phase 1 : functionalisation

phase 2 : conjugation

70
Q

What happens in phase 1 functionalisation ?

A
  • Enzymes : oxidoreductases e.g. cytochrome P450 and hydrolases introduce reactive/polar groups into toxins chemical structure
  • Some become polar positive and are excreted through the kidney
  • Others are now reactive but need further metabolism and enter phase 2
    = SPECIFIC ENZYMES PUT IN POLAR GROUPS ONTO CHEMICAL STRUCTURE - MAKE IT HYDROPHILIC
71
Q

What happens in phase 2 conjugation ?

A
  • Reactive molecules undergo conjugation reactions
  • This makes them stable ( non-reactive ) but water soluble ( hydrophilic ) can be excreted via urine , bile and stool - end up with hydrophilic compound in end
72
Q

What are 2 pathways of conjugation

A

Sulfation - Adding sulfur groups

Acetylation -Adding acetyl groups

73
Q

What does phase 1 leave you with

A

Functionalised molecule thats now reacted

74
Q

Why do we need massive reserves of nutrients in the liver

A

For metabolism

75
Q

What does bile contain ?

A 
. water
. cholesterol
. bile salts
. buffering ions ( bicarbonate )
. bile pigment ( bilirubin and biliverdin )
76
Q

What is pH and colour of bile

A

PH 8

greeny yellow in colour

77
Q

Function of bile

A
  • Secreted into duodenum

- Aids in digestion of fats

78
Q

Where does bile flow through when made by hepatocytes ?

A
  • Flows through bile canaliculi between cells
  • Flows into common bile duct
  • Stored in gall bladder
79
Q

What is secretion of bile into duodenum controlled by ?

A
  • Hormones : secretin , gastrin and somatostatin

- Vagus nerve

80
Q

Where are kupffer cells found and what is its function

A
  • Adherent to sinusoidal epithelial cells inside the sinusoid
    Resident liver macrophages
    Perform scavenger and phagocytic functions to remove protein complexes, small particles, senescent red blood cells, and cell debris from the blood
    Also perform immune survelence against gut -derived toxic materials, incuding endotoxin LPS and pathogens from intestinal flora

Biological Sciences (27 decks)

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