Nutrition part 2 Flashcards
(118 cards)
BMI (body mass index)
scale used to measure/quantify “adiposity” (just an estimate, bc not specific to body fat in calculation)
* weight lifters can have falsely high BMI, *doesn’t apply to children – use separate chart (age and sex adjusted)
BMI= mass (kg)/(height (m)^2)
VLDL
Produced in liver,
Carries triglycerides and cholesterol to extra-hepatic tissues.
ApoB-100…+ApoC II and ApoE
Cholesterol biosynthesis
Energetically demanding,
Get Cs from acetyl CoA
Uses 6 ATP and I NADH, also: HMG-CoA Reductase,
* dolichol, heme A, and ubiquinone
Rate limiting step of cholesterol synthesis
HMG-CoA Reductase, in ER Limited by: - gene transcription - protein turnover - post translational modification Feedback regulation: cholesterol
HMG-CoA Reductase regulators
inhibition: AMP-activated protein kinase (+AMP, + sterols)
Activation: phosphatase (+insulin)
Sterol regulatory binding protein (SRBP)
Transcription factor in ER…
When low cholesterol: moves to Golgi, gets cleaved by proteases, goes to nucleus and stimulates expression of HMG-CoA reductase gene
Statins
Medication type used to lower cholesterol,
= competitive inhibitor of HMG CoA Reductase
(AND promotes SREBP via cholesterol feedback loop –> increase LDL receptors and cholesterol uptake by cells)
ie: Lipitor, zocor, lovastatin
Lipoprotein
Soluble, specialized lipid transport molec.
= amphipathic alpha helix (proteins to outside, lipids to middle)
Structural components: apolipoproteins (“baggage tags”)
- ApoA, ApoB, ApoC, etc
4 types of cholesterol (sizes)
VLDL- very low density 0.95-1.006. Trig.
IDL - intermediate density 1.006-1.019.
LDL - intermediate density 1.019-1.062. Cholesterol esters and cholesterol
HDL - high density 1.062-1.210. Cholesterol ester and cholesterol.
*each with own apolipoprotein
Chylomicron
Smallest lipoprotein, Produced in intestinal enterocytes, Carries triglycerides and cholesterol (from small intestine to organs) ApoB-48 ... + ApoC II and ApoE
LDL
Made from VLDL when lose triglyceride.
Main carrier of cholesterol and cholesterol esters to peripheral tissues or liver for excretion.
HDL
Produced in liver and intestine.
* for reverse cholesterol transport!
(Exchanges apolipoproteins and lipids between particles)
Uses ApoA I, ApoC II, and ApoE
Lipoprotein lipase regulation
activated by ApoC-II
(*ApoC-II repressed in fat during fasting but NOT in m)
Also: gene expression… + insulin, feeding; - fasting
(LPL= enzyme to convert cholesterol from VLDL to fatty acid and monoacylglycerol)
Reverse cholesterol transport
By HDL,
Transport of cholesterol back to liver to be excreted
*exchanges from tissue to LDL (transporter) via cholesterol ester transfer protein (CETP)
ATP-binding cassette protein
Required by HDL to get cholesterol from tissue,
(So can send back to liver)
Powered by ATP hydrolysis,
Transports cholesterol from inner leaflet of plasma membrane to outer leaflet
LCAT (lecitin:cholesterol acetyl transferase)
Enzyme on HDL that converts cholesterol from tissue (from ABC protein),
Converts to cholesterol ester
Foam cell
A macrophage engorged with lipids.
First gross indicator of atherosclerosis
Nitrogen balance
Nitrogen taken in should equal nitrogen lost
In: digestion and AA absorption
out: excreted in urine (urea and ammonia) and and lost in skin and feces
*to maintain free AA pool
Types of Nitrogen IMbalance
Positive - childhood growth, lactation, injury recovery
Negative = (1 or more AAs missing from pool; cannot replace normal protein loss) – traumatic injury, cancer, malnutrition
* Cachexia: - N bal.–> muscle loss, fatigue, etc.
— NOt fixable by diet (from cancer, AIDs, trauma, etc)
Kwashiorkor
Severe protein insufficiency,
w/ moderate energy intake
–>edema,
Permament growth stunting, mental disability
Marasmus
Severe protein AND energy insufficiency,
Little muscle mass, little/no fat, poor strength
Permanent growth stunting, mental disability
Transport of nitrogen through body
In form of AAs (esp. Ala, glut)
Bc ammonia and urea = toxic
– conversion to ala/glut by transaminases (swap amino grps)
(Works for all AAs except lysine and threonine)
* Vit B6 = cofactor
Glutamine synthetase
Makes glutamine from NH4+ and glutamate, uses ATP
In peripheral tissue and muscles
(Reverse once in liver = glutamate dehydrogenase)
Glutaminase
Converts glutamine to glutamate and ammonia
in liver, kidney
(= reverse of glutaminase rxn, used to convert glut from transport back to useful molecs – esp. glutamate)