The Liver
description
Transcript of The Liver
![Page 1: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/1.jpg)
The Liver
![Page 2: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/2.jpg)
1450 cm3 of bloodflows through theliver every minute.
Wide range offunctions;
1)Amino acids to glucose.
1450 cm3 of bloodflows through theliver every minute
2)Metabolism of fat.
3) Synthesis of Triglycerides.
4) Synthesis & regulationof cholesterol.
5) Deamination/transamination/urea formation
6) Production ofbile.
7) Detoxification
![Page 3: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/3.jpg)
A – Liver
B – Hepatic vein
C – Hepatic artery
D – Portal vein
E – Bile duct
F – Stomach
G – Cystic duct
H – Gall bladder
![Page 4: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/4.jpg)
Blood enters the liver through twovessels:
1)Hepatic artery2)Portal vein
3x the blood enters via the Portal vein.
The blood here comes from the small intestineit is rich is dissolved nutrients.
The blood here is deoxygenated and at low pressure compared to the hepatic artery
![Page 5: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/5.jpg)
Small intestine
Liver
Stomach
Pancreas
AORTA
VENA CAVA
![Page 6: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/6.jpg)
Histology of the liver……
2mm
Liver Lobule.
Central vein
HP vein
Hepatic arteryBile duct
![Page 7: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/7.jpg)
Histology of the liver……
There are 10,000 lobules one adult liver
Blood flows up thru.HPV & hepatic art.
HPV
HA
Blood then flows thru.into Central vein thru.SINUSOIDS
Lobules are made of Cells called HEPATOCYTES
Blood then flows tohepatic vein & out
![Page 8: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/8.jpg)
2mm
Histology of the liver……
Bile ducts
Special cells producebile, which flows thru.BILE CANALICULI.
Special cells (KUPFFER)are macrophages that eat bacteria that come in bloodFrom the HPV
![Page 9: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/9.jpg)
CBH metabolism in the liver……Liver stores glycogen and
Hepatocytes respond to insulin& glucagon
GLUCOSE
GLYCOGENGLUCAGON & ADRENALINE
INSULIN
GLYCOGEN25% LIVER
75% MUSCLES
![Page 10: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/10.jpg)
High bloodGlucose level
βcells in the Islets ofLangerhans secrete INSULIN
INSULIN
Glycogen formed
Blood glucosedrops
This occurs inHEPATOCYTES
![Page 11: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/11.jpg)
Low bloodglucose level
αcells in the Islets ofLangerhans secrete GLUCAGON
GLUCAGON & ADRENALINE
Glycogen
This occurs inHEPATOCYTES
High bloodglucose level
![Page 12: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/12.jpg)
CBH metabolism in the liver……
……GLUCONEOGENESIS
Gluconeogenesis – literally ‘making new glucose’
3 biological molecules can be broken down to form glucose;AMINO ACIDS, LACTATE & LIPIDS.
3 biological molecules are initially broken down to formtriose sugars (3C), which are then metabolised into glucose.
There are 3 biochemical pathways, each of which are only used when glucose concentrations are low.
![Page 13: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/13.jpg)
CBH metabolism in the liver……
……GLUCONEOGENESIS
Excess aminoacids Glucose
DEAMINATION
Amino Grp (-NH2) removed
Urea formed
Pyruvate Triose phosphate
![Page 14: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/14.jpg)
CBH metabolism in the liver……
……GLUCONEOGENESIS
Excess lipids
Glucose
HYDROLYSIS
Fatty Acids
Triose phosphate
Glycerol
![Page 15: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/15.jpg)
CBH metabolism in the liver……
……GLUCONEOGENESIS
Lactate GlucoseTriose
phosphate
Pyruvate
What is Lactate?By product of anaerobic respiration, very common in large muscles.
![Page 16: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/16.jpg)
Lipid metabolism in the liver……
Gluconeogenesis only occurs when blood glucose levels are low. When glucose levels are high, lipids are produced.
So excess glucose forms lipids, lipids are needed for;
Energy store in adipose cells
Used in respiration to produce ATP
Cell structures (membranes)
Formation of steriods, which then form hormones
![Page 17: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/17.jpg)
Lipids as an energy source……
Lipids are used as energy sources even when blood glucose levels are high.
Often fatty acids are used as a preferred energy source, this is particularly true of cardiac muscle.
Triglycerides are broken down into glycerol and fatty acids (hepatocytes),the fatty acids are broken down into acetyl coenzyme A, this is then fed into the Krebs Cycle, producing ATP.
![Page 18: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/18.jpg)
Glycerol3 fatty acids
TRIGLYCERIDE
GlycerolGlucose
Triose phosphate1
2
AcetylCoenzyme
A
ATP
KREBSCYCLE
Lipids as an energy source……
![Page 19: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/19.jpg)
Synthesising triglycerides……Once lipids are synthesised, they are converted toTRIGLYCERIDES and then stored in adipose tissue.But, lipids are insoluble in water, meaning they are difficult to transport.They are converted to LIPOPROTEINS as low density lipoproteins (LDLs)
For each fat that needs transporting, there is specificlipoprotein that does the job – the all have different densities.
![Page 20: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/20.jpg)
Synthesising & regulating cholesterol……
The liver makes cholesterol.Cholesterols functions are:1) Cell membrane stability.2) Cell membrane fluidity.3) Membrane barrier tohydrophilic substances.
4) Synthesis of steroid hormones (oest/test)
5) Deposited under skin, making it waterproof.
6) Involved in Vit D synthesis.
7) Involved in synthesis of bile salts.
![Page 21: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/21.jpg)
Synthesising & regulating cholesterol……
Meat, eggs and other
diary products have high cholesterol.
When you eat lots of these foods, your liver synthesises lessless cholesterol.
This is called dietary cholesterol.
High levels of dietary cholesterol
stops……
Acetyl Coenzyme
A
CHOLESTEROL
..Enzymes
So high levels of DIETARY CHOLESTEROL
does not always lead to high BLOOD CHOLESTEROL
![Page 22: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/22.jpg)
Synthesising & regulating cholesterol……
Alternatively, if your diet contains high
levels of SATURATED FATS…
…synthesis of cholesterol increases.
No C-C double bonds,
e.g. all C-H bonds
Lots of evidence to suggest that
geneticsHas a role to play
![Page 23: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/23.jpg)
Transporting cholesterol……
Cholesterol is a lipid, therefore not
water soluble.
It is also transported in LIPOPROTEINS.
It is transported as either…….
High Density Lipoproteins HDLs
These are good for you.Protecting you from LDLs
May also remove LDLs
Low Density Lipoproteins LDLs
These are not good for you.They deposit cholesterol on
walls of arteries (AKA plaques)
![Page 24: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/24.jpg)
Protein metabolism……
Convert one amino acid to another -
AKATRANSAMINATION.
Removing excess amino acids - AKA
DEAMINATION.
Production of urea – linked to
DEAMINATION.
Production of 3 blood proteins – FIBRINIGEN/ALBUMIN/GOBULIN
S
![Page 25: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/25.jpg)
TRANSAMINATION - converting one amino acid to another.
If our dietary intake of amino acids does not match the bodies requirements, then the liver has the ability to add/remove elements from R groups inorder to make new amino acids.
There are a group of amino acids that the body can not do this with, they are called ESSENTIAL AMINO ACIDS.
![Page 26: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/26.jpg)
DEAMINATION – removing excess amino acids.
If our dietary intake of amino acids exceeds the bodies requirements, then the excess needs to be removed.Deamination removes the AMINE GRP (-NH2), with the rest of the molecule being converted to CBH or fat.The AMINE GRP (NH2) is converted to AMMONIA (NH3) – this is very soluble and toxic, so is not around for long!
It is then combined with CO2 using ATP to produce UREA (CO(NH2)2 this occurs in the ornithine cycle.
![Page 27: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/27.jpg)
The ORNITHINE CYCLE. Deamination NH3
CO2
ATP
ATP
UREACO(NH2)2
![Page 28: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/28.jpg)
SYNTHESIS of PLASMA PROTEINS………
There are 3 important proteins in blood;•Fibrinogen•Globulin•Albumin
Each of these proteins are globular and are produced in the liver.
Hwrk: Read and make notes on
GLOBULIN & ALBUMIN (pg 24).
![Page 29: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/29.jpg)
SYNTHESIS of PLASMA PROTEINS………
Damage to blood vesselsleads to the collagen fibres
being exposed, this stimulatesplatelets.
Prothrombin
Thrombin
Fibrinogen
Fibrin
Thrombin – an enzyme, which catalyses the removal of AA from fribrinogen, to allow it to polymerase and form FIBRIN.
Fibrin is an insoluble protein that forms long fibres, they tangle up trapping rbcs and leading to a clot.
![Page 30: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/30.jpg)
Production of BILE………
2mm
Bile ducts
Special cells producebile, which flows thru.BILE CANALICULI.
1000cm3 of bile is produced each day
Cholesterol made in theLiver is needed to prd. bile
Bile to gallbladder
![Page 31: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/31.jpg)
Production of BILE………
BILE is composed of water & BILE SALTS.
BILE SALTS emulsify fats, then LIPASE can act on thelarger surface area.
BILE SALTS also contain cholesterol – if there is too muchcholesterol or not enough water, gall stones can form.
They can block bile duct and interfere with lipase digestion.
![Page 32: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/32.jpg)
BILE & dead RBCs………
RBCs only live for about 120 days, then they are broken down in the spleen.(below the heart, lower than the diaphragm).
HAEMOGLOBIN is broken down in the LIVER into HAEM &GLOBIN.GLOBIN is broken down into its constituent AA, these are then recycled.
HAEM is broken down into iron and the greenish yellow product called BILIRUBIN – this is excreted into bile.
![Page 33: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/33.jpg)
DETOXIFICATIONMany drugs/dangerous substances are broken down in thesmooth endoplasmic reticulum of hepatocytes.Metabolising alcohol•Alcoholic drinks contain ethanol (C2H5OH)
•It is lipid soluble, so moves thru. cells very easily.
•Alcohol dehydrogenase catalyses the breakdown of ethanol to ethanal.
•Aldehyde dehydrogenase then catalyses the breakdown of ethanal to ethanoate
•Ethanoate can then enter the Krebs cycle to produce ATP.
![Page 34: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/34.jpg)
ETHANOL ETHANAL ETHANOATE
The KREBS CYCLE
ALCOHOLDEHYDROGENASE
ALDEHYDEDEHYDROGENASE
Oxidised NAD
Reduced NAD
Reduced NAD
Oxidised NAD
DETOXIFICATION of ALCOHOL
If you drink too much, reduced NAD builds up and levels of oxidised NAD become low. These means fatty acids build and a condition called ‘fatty liver’ develops.
![Page 35: The Liver](https://reader036.fdocuments.us/reader036/viewer/2022062409/56814816550346895db5423e/html5/thumbnails/35.jpg)
DETOXIFICATION of ALCOHOL
Drinking too much leads to......•Low levels of oxidised NAD, failure to metabolise fatty acids and ‘fatty liver’ develops.
•Destruction of hepatocytes, leads to replacement with inferior hepatocytes.
•Reduced blood supply to the lobules
•This is called CIRRHOSIS
The liver can not function properly, e.g. NH3 builds up and canLead to coma and death in extreme cases