Classes 6 & 7 (Last Quiz) Flashcards
True or false: eicosanoids, including prostaglandins and leukotrienes, are lipids
true
What are the 4 functions of lipids in the body?
fuel
energy storage
thermal/electrical insulation
structural components of cellular membranes
What are the proteins in lipoproteins called? How are they named?
apoproteins
named A, B, C, D, or E plus a number
What are the 4 categories of lipoproteins?
chylomicrons
VLDL (very low density lipoprotein)
LDL (low density lipoprotein)
HDL (high density lipoprotein)
Which type of lipid is the largest in size but the lightest in weight?
chylomicrons
What is the function of chylomicrons?
transporting dietary lipids to adipose tissue
What percentage of chylomicrons are proteins?
1-2%
How long do chylomicrons remain in the blood? Where do they travel, mainly?
only for a few minutes
lymphatic system
What happens to chylomicrons circulating through adipose tissue?
the fatty acids are removed from the triglycerides by enzymes, then taken by adipocytes for synthesis and storage as triglycerides…. weird
VLDL’s are formed where? What percentage of them do proteins make up?
in the hepatocyte
proteins 10%
What is the function of VLDL?
transporting triglycerides synthesized in the hepatocytes to the adipocytes for storage
What happens to VLDLs in adipose tissue?
fatty acids are removed from triglycerides and then taken into the adipocytes for synthesis and storage as triglycerides
the triglycerides are deposited in the adipocytes, and the VLDL is converted to LDL
What is the function of LDL?
carries about 75% of cholesterol in the blood to deliver it to tissues
What percentage of LDLs do proteins make up?
25%
What happens to excessive LDL in the blood?
it deposits cholesterol in and around the smooth muscle in arteries, forming plaques
When can’t LDL enter a cell?
once the cell has sufficient cholesterol!
High fat diets increase the production of ____ which elevates ____ levels, the “bad cholesterol”
VLDLs, which elevates LDL levels
HDL lipoproteins are the ____ in size and ____ in weight.
smallest in size, heaviest in weight
What is the function of HDL?
removes cholesterol from body cells and blood to transport it back to the liver for elimination
What percentage of HDL is made up by proteins?
40-45%
The greatest source of cholesterol in the body is from…
hepatocytes (endogenous)
How does high intake of fatty foods (even without cholesterol) increase cholesterol?
stimulates reabsorption of cholesterol-rich bile
Therapies to lower blood cholesterol must also include raising…
HDL levels
What is the most important factor in raising HDL levels?
aerobic exercise
Drug therapies for high cholesterol will either…
- promote excretion of bile in the feces
2. block cholesterol synthesis
True or false: thromboplastin and myelin sheaths make use of lipids
truw
The subcutaneous layer of the body contains about __% of stored triglycerides
50%
Adipose tissue contains __% of the body’s energy reserves (in the form of triglycerides)
98%
Lipolysis is the process of ______ where triglycerides are broken down into….
beta oxidation
3 fatty acids and one glycerol molecule
Insulin ___ lipolysis, whereas E & NE ____ lipolysis
inhibits
enhance/promote
True or false: fatty acids can be converted into glucose in the body
FALSE
Where does beta oxidation occur?
in the mitochondria
Beta oxidation breaks fatty acids into 2-carbon pieces, which enzymes will then use to form…
acetyl CoA to enter the krebs cycle
One 16-carbon fatty acid (palmitic acid) can yield as many as ___ ATP molecules
129
Hepatocytes can take 2 acetyl CoA and condense them into ketone bodies (via ketogenesis). Then, these ketone bodies can be taken into cells and used to form….
acetyl CoA
The ___ and ____ PREFER to use acetoacetic acid (ketone bodies) in preference to glucose for generating ATP
HEART and RENAL CORTEX
Lipogenesis is stimulated by what hormone? And conducted by what cells?
insulin
hepatocytes and adipose cells
What is the pathway for amino acids to become triglycerides?
amino acids -> acetyl coA -> fatty acids -> triglycerides
Rank proteins, lipids and carbs in order from least amount of energy lost in the transfer to storage, to most lost.
lipids only lose 1-3% in the transfer
carbs lose about 6-8%
proteins lose about 25-30%
Protein catabolism is stimulated by what hormone?
cortisol
What happens to excess dietary amino acids?
they are NOT excreted in the urine or feces, they are converted to glucose (gluconeogenesis) or triglycerides (lipogenesis)
What is deamination? Who accomplishes it?
when the amino group (NH2) is removed from an amino acid, preparing it to enter the Kreb’s cycle
HEPATOCYTES!
Deamination produces highly toxic ____ which will be converted to ___ by ____.
ammonia (NH3) which will be converted to UREA by hepatocytes.
Excess ketone bodies can cause…
metabolic acidosis
Protein anabolism is promoted by what hormones?
growth hormone
thyroid hormones
insulin
estrogens & testosterone
Nonessential amino acids can be synthesized by the body via _____
transamination
G6P is a precursor to ribose, used for __/__ synthesis
DNA/RNA
Acetyl CoA can/cannot be converted back to pyruvate in mammals…
CANNOT
Shell temperature is usually ___* colder than core temperature, which is normally _
1-6* cooler, 37*
____ hormones are the main regulator of BMR
thyroid hormones
A 1 degree increase in core temperature increases metabolic reactions by __%
10%
Food-induced thermogenesis is greatest after meals high in _____
protein
TOTAL ENERGY EXPENDITURE… break it down into 3 categories & their percentages:
BMR: 60%
Physical activity: 30-35%
Food-induced thermogenesis: 5-10%
Leptin helps decrease _____ by acting on the ____ to ____ the stimulus to eat
adiposity
hypothalamus to INHIBIT
What is the function of neuropeptide Y?
it increases motivation to eat, especially carbohydrates
What is the function of melanocortin? What triggers its release?
leptin triggers its release from the hypothalamus. melanocortins are a group of hormones (like MSH, ACTH) that inhibit food intake
1 calorie is equal to…
the amount of heat required to raise one gram of water one degree
