Lecture 9 Flashcards
how are lipids digested
emulsification
what do bile salts increase
surface area
what happens first, emulsification, digestion, or absorption
emulsification then digestion then absoprtion
what are mixed micelles
- allow for easier transportation
Monoglycerides + FFA + Bile slats + Phospholipids + Cholesterol
what create larger mixed micelles
mixed micelles combines with cholesterol and fat-soluble vitamins
where is the main sight of absorption
upper jejunum
what happens to lipids upon entering mucosal cell
- fats reassembled into triglycerides
- protein coating occurs to form chylomicrons
- chylomicrons enter lacteals via intercellular space
how do mammals absorb long chain FA lipids
via lymph system
lipoprotein
lipids + proteins
what is different with chickens when absorbing long chain FA lipids
absorb it directly into portal blood
how are lipids transported
- blood lipids
- as lipoproteins
blood lipids
- chylomicrons
- lipids arising from mobilized depot stores
- lipids synthesized in body tissues
what are the 4 major classes of lipids transported as lipoproteins
- chylomicrons (smallest)
- VLDL (very low density lipoprotein)
- LDL (low density lipoprotein)
- HDL (high density lipoproteins)
which lipoprotein has the highest ratio of lipids to protiens
HDL
which lipoprotein has the smallest amount of proteins
chylomicrons
What is associated with bad cholesterol
LDL
promote plaque formation blood vessels
what is associated with good cholesterol
HDL
break down plaque in blood vessels
how is triglyceride stored
- all cells in body store lipids
- adipocytes (fat cells) are most notable
what happens when there is a negative balance of energy
tissues used by body because it needs energy
lipogenesis
building fatty acids and triglycerides from precursors
where does lipogenesis occur
- liver
- mammary gland
- adipose tissue
FA and TG metabolism in liver
degradation of:
- FA phospholipids
- saturation, desaturation, lengthening, shortening, deposit of liver lipids
biosynthesis of fatty acids process
- begins with acetyl-CoA
- assembled in 2C units
- desaturation in tissue limited
- start with a base and continuously add 2C
what do microbes convert FA’s to become in ruminants
more saturated
triglyceride catabolism
- adipose tissue
how does adipose tissue play a part in catabolism of triglyceride
- composed primarily of triglycerides
- dynamic tissue= synthesis and degradation of triglycerides
- lipoprotein lipase= hydrolysis of TG
- activity under hormone control
in the hydrolysis of TG, when is activity high and low
high- fed state
low- fasted state
what is the hormone in TG catabolism
- lipolysis: fat breakdown
- stimulated by: paylean and GH
- inhibited by: prostaglandins and insulin
what is involved in the control of net fat accretion
- complex regulatory systems
- lipolysis and lipogenesis
fatty acid catabolism
-FA released from hydrolysis= transported to tissues as oxidative energy
- beta oxidation
beta oxidation
stepwise enzymatic removal of 2C units to be used for:
- re-synthesis of FA
- synthesis of steroids and ketones
- entry into TA cycle
where energy comes from
where does beta oxidation occur
- mitochondria
- what comes in: FA and dehydrogenase
- what comes out: shorter FA, electrons, and acetyl-CoA
what makes fats so energy dense
high ratio of C and H to O
steroid metabolism
- cholesterol (most abundant sterol and precursor)
- biosynthesis of acetyl-CoA
- cholesterol excreted in bile
- used for steroid synthesis
phospholipid metabolism
- lecithin most abundant animal tissue because of lipid bilayer
ketone metabolism
- formation of ketones= continous
- energy source in skeletal muscle and other peripheral tissue
- can have overproduction
fatty liver abnormality
- negative energy balance
- excessive fat mobilization from adipose tissue
- fat dpeosited in liver slower than net lose
how do you prevent fatty livers
- transition period is important
- feeding protected choline
- dairy cattle
ketosis
- rapid mobilization of fat depot
- reduced intakes
- lack of ability to metabolize acetyl-CoA in TCA cycle
obesity
- over consumption of calories= factor
- genetic=factor
- net deposition greater than normal
- cell size and number
what can occur postnatally to cause obesity
proliferation
