M103 T3 L5

Question 1

What is the role of steroids and FAs?

Answer 1

regulatory roles as hormones, vitamins and bile acids

Question 2

In what form is E stored in for short term?

Answer 2

Redox agents (NADH, FADH2)
Ionic transmembrane gradients
ATP (phosphate bonds)

Question 3

How are carbohydrates handled by the body from the point of entry?

Answer 3

Starch is digested into sugars (glucose) in gut
Sugars are absorbed from gut into blood stream
Sugars are absorbed into the liver via the hepatic portal vein where they are stored as glycogen

Question 4

Is glycogen stored in the brain and why?

Answer 4

no bc there is nearly no glycogen in brain
the brain needs either glucose directly, at the very moment that it’s consuming energy, or ketone bodies from plasma constantly

Question 5

What happens in the citric acid cycle?

Answer 5

starts with a (4C) OAA inside the cell
OAA + 2C (from acetyl co-A) = 6C citric acid
citric acid + o2 = OAA (+co2 + ATP + NADH + FADH)

Question 6

What is the equation for FA synthesis?

Answer 6

acetyl CoA + ATP + E- = FA + CoA + CO2

Question 7

What happens in beta oxidation?

Answer 7

a long FA uses E to break it down into acetyl CoA + e- + ATP

Question 8

In humans how long are most FAs? What percentage of them have double bonds?

Answer 8

mostly 16-20 carbons long

50% have double bonds

Question 9

What are the two ways cholesterol comes to be in the body?

Answer 9

made by the liver

received from diet

Question 10

Why and how does the body recycle cholesterol?

Answer 10

it takes lots of E to generate

recycles it from the bile salts

Question 11

What is the main form of cholesterol in the body? How is it used?

Answer 11

esterified cholesterol - 75%

lipase breaks it down into FAs and free cholesterol

Question 12

How is vitamin D is produced by the skin?

Answer 12

by the action of light on a cholesterol derivative

Question 13

What chemical is made from acetyle co-A during fasting and how is it useful?

Answer 13

ketone bodies from the liver

can be used as E if in the blood esp by the brain and heart

Question 14

How long do ketone bodies last?

Answer 14

short lived in the blood - only lasts 5 hours

Question 15

What are the features of unsaturated FAs?

Answer 15

have a lower mp - more liquid at body temperature, results in increased fluidity of the cell membranes

Question 16

What are the most naturally occurring unsaturated FAs?

Answer 16

nearly all are cis - they have an even number of carbons from 14 to 22

Question 17

Why are saturated fats are popular with manufacturers of processed foods?

Answer 17

they are less vulnerable to rancidity and are, in general, more solid at room temperature than unsaturated (plant) fats

Question 18

What are the degree angles for cis and trans?

Answer 18

cis - 123

trans - 132

Question 19

What types of fats are bad?

Answer 19

Saturated fats - bad bc they increase LDL

Trans unsaturated fats - bad (processed food)

Question 20

Are cis unsaturated fats bad and if so, why?

Answer 20

they are not as risky as saturated fats and trans fats
They have a lower mp bc of kinks - less likely to solidify into fat
However, high melting temperature is bad for unsaturated fats - solid & unmobilisable - will become solid lump of fat that can’t easily be broken down

Question 21

What are the four different pathways for lipid transport?

Answer 21

exogenous & endogenous pathways
reverse cholesterol pathway
bile production

Question 22

What happens in the exogenous pathway?

Answer 22

lipids from the diet in the gut are packaged by the SI into chylomicrons
these are taken from the blood vessels of the GI tract toward where they have to be stored - liver

Question 23

What happens in the endogenous pathway?

Answer 23

lipids are made by the body (the liver releases stored or generated) fats
packaged into LDL
takes lipids from the liver to the periphery

Question 24

What happens in the reverse cholesterol pathway?

Answer 24

the pathway takes lipids from the periphery to the liver
occurs when lipid supplies in liver are being exhausted
e.g. exercise or starving
serves as a sign of reduced body lipid
HDL in blood indicates that there is activity in the reverse path activity

Question 25

What happens in the pathway of bile production?

Answer 25

the pathway takes lipids from the liver to the digestive tract cholesterol is made into bile by the liver on eating a fatty meal, the liver releases bile salts into cystic duct leading to the gall bladder and emulsifies fats most bile acids are reabsorbed by gut they are returned to the liver and recycled until they are excreted in stool

Question 26

What do lipoprotein lipases do?

Answer 26

they are a cell surface-linked enzyme in capillary walls they can't metabolise triglyceride bc won't fit through membrane so breaks it down into FAs and glycerol IOT remove triglycerides from VLDL and to move the TG across the capillary membrane, TG must first be metabolised via lipoprotein lipase

Question 27

What are lipoprotein particles made up of?

Answer 27

apolipoproteins & lipids

Question 28

What are the densities of triglycerides and cholesterol like?

Answer 28

Triglycerides are very low density | Cholesterol is mid-way between TGs and proteins

Question 29

What is the most dangerous lipoprotein type and why?

Answer 29

LDLs bc a high presence in the blood is a sign of risk for CAD Excess LDL accumulates in atheromas

Question 30

Is HDL a bad or good lipoprotein and why?

Answer 30

not as bad as LDL increased HDL = lower CV risk HDL leads to lipid transport from the fat cells to the liver - reverse cholesterol transport usually appears when cholesterol is being used up

Question 31

What do high levels of VLDLs signify?

Answer 31

an increase risk of atheroma

Question 32

What are the functions of chylomicrons?

Answer 32

Not usually associated with CV risk - is normally high after fat-containing meals Carries exogenous lipids from the gut to the periphery for storage

Question 33

Which cells in the pancreas release what two hormones?

Answer 33

β-cells release insulin | α-cells release glucagon

Question 34

What are features of Type II Diabetes Mellitus?

Answer 34

High blood glucose Insulin resistance Relative Insulin Deficiency

Question 35

What are the two causes of Type II Diabetes Mellitus?

Answer 35

obesity | genetic predisposition

Question 36

What are the two causes of Hypercholesterolaemia?

Answer 36

a combination of environmental and genetic factors

Question 37

What do statins block?

Answer 37

endogenous cholesterol synthesis HMG-CoA Reductase the entry step into cholesterol synthesis

Question 38

What are the main causes of metabolic syndrome?

Answer 38

Insulin resistance Central obesity, waist circumference high bp

Question 39

How many amacs long is a long FA?

Answer 39

between 16-20 amacs long

Question 40

How does the size of TGCs and cholesterol correspond with density?

Answer 40

Bigger lipoprotein particles usually are carrying a lot of lipids - thus lower in density

Question 41

What is the role of VLDL?

Answer 41

to transport endogenous cholesterol and TGCs from the liver to the peripheries

Question 42

What is a consequence of the fact that VLDL being launched from the liver has fat inside it?

Answer 42

the more VLDL present in the blood, the more fat and tryglycerides are being thrown out of the liver

Question 43

What happens after the VLDL gets to the periphery?

Answer 43

the TGC is removed from the periphery VLDL is turned into IDL IDL will become LDL

Question 44

What is the difference between VLDL and IDL?

Answer 44

VLDL is the same molecule but has a lower density

Question 45

What is the relationship between LDL and VLDL?

Answer 45

LDL is eventually “left-over” after periphery absorbs endogenous TG from VLDL from liver

Question 46

What are the products of fat mobilization?

Answer 46

ATP + Acetyl-CoA

Question 47

By what vessel are sugars absorbed into the liver?

Answer 47

the hepatic portal vein