lipid digestion, absorption and transport Flashcards
what are the three major classifications of lipids
triglycerides
phospholipids
steriods
what are triglycerides
glycerol backbone with three fatty acids
what are steroids
ring structures
give examples of steroids
cortisol
oestrogen
testosterone
cholesterol
what are phospholipids
Phospholipids are made of 2 fatty acids and a phosphate group and they are a major component of the cell membrane.
what are the three main types of fatty acids
monounsaturated
polyunsaturated
saturated
do lipids dissolve in water
no they are hydrophobic and insoluble which means we need to emulsify them to transport and absorb
what are monounsaturated fatty acids
1 carbon double bond
give examples of foods that have monounsaturated fatty acids
seeds or nuts avocado olive peanut canola
what are polyunsaturated fatty acids
have more than one carbon doible bond
give examples of foods that have polyunsaturated fatty acids
vegetables, seeds or nuts such as corn, safflower, sunflower, soybean, cottonseed and sesame seed oils.
what state is unsaturated fats at at room temp
liquid
what state is saturated fats at at room temp
solid
what are saturated fats
have only carbon carbon single bonds
give examples of foods with saturated fats
butter ghee cheese milk coconut oil
which type of fats raise cholesterol
saturated
what type of fats reduce cholesterol
monounsaturated in the right amounts reduces cholesterol and LDL cholesterol
give an example of polyunsaturated fats
omega three fatty acids
what are trans fats
when veggie oils are hydrogenated into shortening
what are the functions of lipids
body fuel once carbs used up
helps body absorb important fat soluble vitamins
supports body processes such as biosynthetic precusors
cushioning internal organs
insultioon
maintaining healthy skin and hair
what fat soluble vitamins are absorbed
ADEK
how many cals does 1g of fat provide
9 cals
what is associated with XS fat intake
obesity, diabetes, cancer, hypertension and atherosclerosis.
how much % of energy intake should come from fat
35%
how much of this should be saturated fats
10%
what is the total grams of fat intake
65g
what can protect us from atherosclerosis
omega 3 fatty acids
how many times should we eat fish a week
2-3
where does lipid digestion first occur
the oral cavity- lingual lipase and mechanical digestion
which enzymes are involved in the stomach
lingual lipase and gastric lipase
how much fat breaks down after 2-4 hours
30%
what are acidic lipases
lingual lipase and gastric lipase as they are stimulated and increased by acidity
what happens in the SI
acid chyme (stomach contents) stimulates mucosa cells to release a hormone (choleocystokinin) which stimulates gall bladder and pancreas to release bile and digestive enzymes respectively (bile salts help emulsify fat droplets thus increasing their surface area exposed for digestion and pancreatic Lipase breaks down Triglycerides and diclycerides to 2- monoglycerides and fatty acids).
describe bile salts
a hydrophobic and a hydrophilic side, their hydrophobic side attaches itself to the lipids and emulsifies it increasing the surface area that can be acted upon by the pancreatic lipase
which medications are used for the treatment of obesity
orlistat or xenical
how does orlistat or xenical work
pancreatic lipase which inhibits digestion and absorption
what is the product when triacylglyceride is digested by pancreatic lipase
fatty acid x2
2 monoacylglycerol
what is cholesteryl ester broken down by
cholesteryl ester hydrolase
what is a micelle
fatty acids which are associated with bile salts and other structures
what is the diameter of a micelle
4-8nm in diameter
what lines the intestinal lining cells
enterocytes
how do the phsopholipids and micelles neter the enterocytes
simple diffusion
clinically what is seen if fats arent absorbed properly
fats seen in stools steatorrhea.
how can steatorrhea arise
from crohns disease and fibrosis done upto slide 10
describe the passage of lipid absorption
the micelle simply diffuses into the enterocytes then through the basolateral border and into the lymphatic and vascular circulation
what happens to the triglycerides in the enterocytes
triglycerides are reassembled and they are combined with apoproteins phospholipids and cholesterol
what is combined with the triglycerides in the ER
phospholipids
apopproteins and cholesterol
what forms chylomicrons
apoproteins
phospholipids
cholesterol and triglyercides
where are chylomicrons packaged
in the golgi apparatus
what is the passage of chylomicrons
formed in the ER
packaged into vesicles in the golgi
leave the intestinal cells basolateral border by exocytosis
where do chylomicrons travel to
transported to the lymph vessels in the intestine via central lacteals and enter the blood circ by thoracic duct
what class of lipoproteins has the highest content of lipids
chylomicrons
what class of lipoproteins has the lowest content of lipids
HDL
what percentages of lipid and protein does HDL have
50% lipid AND protein
what percentages of lipid and protein does cholesterol have
99% lipid and 1% protein
what are chylomicrons mostly made out of
triacylglycerides
where are triglycerides cholesteryl ester and cholesterol stored
in peripheral areas such as heart muscle skeletal muscle and adipose tissue and lactating mammary tissue
where are remainig chylomicrons taken up
by the liver
what is VLDL
very low density lipoproteins
describe VLDL
the liver that is analogous to the chylomicrons secreted by the intestine. Its purpose is also to delivertriglycerides, cholesteryl esters, and cholesterol to peripheral tissues.
when the VLDL is depeated of its contents it becomes intermediate density lipoproteins which returns to the liver
what are LDL
low density lipoproteins
what is the principle role of LDL
deliver cholesterol and cholesteryl ester to peripheral tissues
what is the role of HDL
in the removal of excess cholesterol from cells and returning it to the liver, where it is metabolized to bile acids and salts
if HDL is high in humans what can happen
correlate well with a lower incidence of atherosclerosis in humans.
what happen in artiers if the LDL is too high
can form fatty deposits in arteries and damage linings- leading to stroke and MI
what is hyperlipidaemia
high levels of lipid found in the bloodstream- found by a lipid panel
what is cholesterol synthesised by
HMG-CoA reductase enzyme in the liver
how do statins work
competitively inhibiting HMG-CoA reductase therefore cholesterol isn’t formed
how do we reduce cholesterol naturally
reduce fat and increase fibre
