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🫀Biochemistry > Lipid Metabolism > Flashcards

Lipid Metabolism Flashcards

1
Q

Steps of Lipid Metabolism

A 
Lipid digestion
Lipid absorption
Lipid transport 
Lipid catabolism
Lipid biosynthesis
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2
Q

Functions of Lipids

A 
Energy
Cell membranes
Cell signalling
Facillate absorption of fat-soluble vitamins
Biosynthetic precursors
Protection and Insulation
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3
Q

Lipid Digestion

A

Lipase enzymes - triglyceride -> monoglycerides
MOUTH
Ligual Lipase = chemical digestion
STOMACH
Gastric Lipase = chemical&mechanical digestion
SMALL INTESTINE
Pancreatic Lipase + Bile Salt = from pancreas to small intestine + bile salt emulsifies lipids

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4
Q

Cholecystokinin

A

Digestive hormone

Stimulate release of pancreatic lipase from pacreas + release stored bile salts from gall bladder into intestine

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5
Q

Bile salts

A

Amphiphatic compound that emulsifies fat to form micelles

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6
Q

Pancreatic Lipase

A

hydrolyse triglycerides into monoglycerides - FA and glycerol

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7
Q

Lipid absorption

A

1) FA and monoglycerides are emulsified by bile salts to form micelles
2) FA enter epithelial cells and form triglycerides
3) Combine with proiteins inside golgi body = CHYLOMICRONS
4) Enter lacteal ( lymphatic capillary that absorbs dietary fats in villi of small intestine) and transported away from intestine

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8
Q

Chylomicrons

A

Amphipathic vesicles that package lipids into larger particles
Made up of apolipoprotiens/triglycerides/cholestrol/phospholipids
Chylomicrons transport DIETARY triglycerides through bloodstream to liver/adipose/muscle etc
Source = intestine
Lowest density - highest density of TGs

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9
Q

Feasting

A

Excess energy is consumed - stored in adipose tissue as triglycerides

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10
Q

Fasting

A

No food

Triglycerides from adipose tissue are broken down releasing FAs as an energy source

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11
Q

Lipid Transport

A 
Hydrophobic lipids require special transport proteins - lipoproteins 
4 types of lipoproteins 
- chylomicrons
- VLDL
- LDL 
- HDL
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12
Q

VLDL

A

High %TG
Source = Liver
Transport ENDOGENOUS triglycerides to body tissues

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13
Q

LDL

A

Highest %cholestrol ‘BAD CHOLESTROL’
Source = liver
Transport CHOLESTROL to body tissues

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14
Q

HDLS

A

Highest %protein - highest density ‘GOOD’
Source: Liver and Intestine
Transports CHOLESTROL from tissues TO LIVER for breakdown

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15
Q

LIpid Transport

A

Exogenous pathway - DIET - Chylomicrons
Endogenous pathway
Reverse Transport pathway - HDL

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16
Q

Stages of Lipid Transport

A

1) Chylomicrons carry triglycerides from small intestine to body cells
2) Chylomicron remant travels to liver for disassembly
3) VLDL produced by liver brings triglycerides to body cells
4) VLDL becomes IDL and LDL as triglycerides are removed
5) LDL delivers cholestrol to body cells
6) HDL picks up excess cholestrol and delivers to liver for disposal

17
Q

Liver cells in lipid transport

A

Store fats - triglycerides and glycerol
Produce bile from cholesterol
Produce VLDL to deliver triglycerides

18
Q

Lipid Catabolism

A

Chylomicrons are broken down to Lipoprotein Lipase LPL in capillaries of skeletal/cardiac/muscle/adipose tissues
Lipolysis - TG -> FA + Glycerol
Glycerol = Glyceraldehyde 3 Phosphate - Acetly CoA - enter TCA cycle to produce ATP
FA = Acetyl CoA

19
Q

Ketone/Ketone body production

A

produced by liver during starvation when glycogen is depleted (24h)
body uses fat as source of energy

20
Q

DKA

A

Diabetic ketoacidosis

- diabetics/ starvation use ketones as fuel as they can’t use glucose + liver breaks down fat too fast

21
Q

Excess Acetyl CoA

A

Created from beta oxidation and TCA cycle is overloaded = creation of ketones

22
Q

HMG CoA

A

precursor of cholestrol and converted to beta hydroxybutyrate = primary ketone body in blood

23
Q

Synthesis of ketone bodies

A

Acetoacetate - transported to tissues outside liver converted to acetyl CoA and oxidation in TCA cycle = generate energy

Brain adapts to using acetoacetatae or Beta hydroxybutyrate in starvation instead of glucose as fuel

24
Q

Cholestrol

A

Role = Bile acids + Streoid hormones = adrenal/sex

Made from Acetyl CoA

25
Q

Sterol regulatory element binding protein

A

key transcription factor that regulates cholestrol synthesis

26
Q

Statins

A

inhibit cholestrol synthesis by inhibiting HMG-CoA reductase

27
Q

High CVD risk

A

High LDL
Low HDL
Smoking/Diabetes/High BP and family history

28
Q

Atherosclerosis

A

LDL deposit cholestrol in inner walls of arteries
Formation of plaque - reduce blood flow & oxygen to vital organs
Clot forms and blocks narrowed artery = MI/stroke
- endothelial dysfunction
- vascular inflammation
- buildup of lipids/cholestrol/calcium

29
Q

Atherogenesis

A

1) Endothelial dysfunction - aging/smoking/high cholestrol/ heart failure/diabetes
2) formation of lipid layer/fatty streak in vessel wall = LDL/VLDL
3) inflammation - migration of leukocytes and smooth muscle cells in vessel wall
4) foam cell formation - macrophages absorb lipids
5) thrombosis - degradation of extracellular matrix and fibrous cap of a plaque ruptures

🫀Biochemistry (2 decks)

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