nutrition, metabolism, body temp chp 25 Flashcards
metabolism
all of bodys reactions at any given moment
all chemical reactions that take place in the body
catabolism
breakdown of organic substrates
reaction that breakdown large molecules into their smaller ones
anabolism
synthesis of new organic substrates
reactions that build larger molecules from smaller ones
how much ATP is produced in glycolysis
2 atp
how much ATP is produced in aerobic metabolism
34 atp
describe the primary function of glycolysis
- its the first step in breaking down glucose
- anaerobic process taking place in the cytoplasm
splits a 6 carbon glucose molecule into two 3 carbon molecules of pyruvate (makes 2 pyruvates to feed mitochondria with)
- 2 atp from here
describe the primary function of the citric acid cycle (TCA or krebs cycle)
to remove hydrogen atoms from organic molecules and transfer them to coenzymes and deliver them to ETS/ETC
- aerobic
- takes place in mitochondria
95% of atp is made where
in the mitochondria
describe how oxidative phosphorylation works
its the transfer of electrons and attachment of high energy phosphate group to ADP
-produces more than 90% of atp used by our body cellls
-oxygen is the final electron acceptor for oxidative of food molecules
** uses oxygen to add a phosphate molecule to adp to form atp **
the role of coenzymes (NAD + FAD)
transfers hydrogen atoms to cytochromes of ETS
(releases hydrogen ion and passes electron to next until they get to the ETC/ETS)
basically deliver hydrogen atoms from citric acid cycle to ETS
what is a cytochrome?
proteins embedded in the inner mitochondrial membrane that electrons from H atoms are passed to
how is atp produced in the ETS/ETC?
energy provded by the H ion movement back to mitochondrial matrix to eliminate the conc. gradient, activate ATP synthease = phosphorylation of adp to ATP
why are carbohydrates preferred substrates for catabolism
easy energy and function to produce energy
why is protein NOT the preferred substrate for catabolism
because its used for other cell structure or body structure and functions
chlyomicrons are
digested lipids coated with proteins which makes them water soluble and more easily transported in body fluids
-lipoproteins
lipid protein complexes with insoluble lipids (water soluble)
LDL’s /low density lipoproteins
lipids in circulation heading to cells
- bad cholesterol
HDL’s
lipids heading back to liver for recycling
- good cholesterol
lipolysis
breaks down lipid
- these broken down lipids can be converted to pyruvate or directly enter the citric acid cycle
lipogenesis
creating new lipids
what are the 2 general patterns of metabolic activity
- absorptive state
- postabsorptive state
absorptive state
first 4 hours after a meal , insulin is the dominant hormone
- absorbing nutrients here
- high glucose levels
- insulin stimulates glucose uptake
- triglyceride synthesis
postabsorptive state
after 4 hours post meal, glucagon is dominant hormone
- no nutrient absorption
- body relies on energy reserves
- low blood pressure glucose levels
- mobilization of energy reserves
- maintains blood glucose levels at 70-110mg/100mL
- other hormones such as epinephrine , glucocorticoids, GH
what are vitamins
organic compounds that play essential roles in several metabolic pathways
- act as coenzymes to assist enzyme functions
- 2 categories (water and fat soluble ones)
fat soluble enzymes are
A, D, E, K
- absorbed from digestive tract with lipid content of micelles
- involved in hypervitaminosis since they are not easily eliminated in urine
water soluble vitamines
B and C
- mainly components of coenzymes
what vitamines are involved in hypervitaminosis
fat solubles ones since they are not water soluble so not easily eliminated in urine
Describe the primary significance of the vitamins discussed in lecture
vitamin A: visual cycle
B: coenzymes
C: coenzymes
D: healthy bones
E: supports function of vitamin A + fatty acids
K: clotting factors made in liver
how many required minerals in moderate amounts
7
calcium, phosphorous, potassium, sulfur, sodium, chlorine, magnesium
energetics
study of flow of energy and change from 1 form to another
BMR (basal metabolic rate)
minimum resting energy expenditure of someones
true or false: all reactions that generate atp also generate heat
true its 60% heat + 40% ATP
how do we maintain energy balance
by our food intake being adequate to support activites under way
average BMR
70 cal/hr or 1680 cal/day
- but our cal intake depends on weight and activity level
what factors are involved in food uptake?
hormones: Leptin + NPY
body temp - we eat when our body temp is higher
- when body temp is low we are slower and eating isnt that impt to us atm
-psychological ones
BMR IS ___ in elderly people
low
- decreased efficiency of the endocrine system
-decreased wasting
general features of long term regulation of appetite
leptin from adipose tissue stimulate satiety center
- excess calories are stored as fat in adipose tissue
- (slower acting)
short term regulation of appetite
glucose stimulates satiety center (feeling of fullness), NPY + ghrelin stimulate feeding center (hunger)
what is leptin
peptide hormone released by adipose tissue as they make triglycerides (slower acting)
what stimulates the CNS satiety center and supresses appetite
leptin (slower acting)
what is neuropeptide Y (NPY)
hypothalamic neurotransmitter that stimulates feeding enter - increasing appetite
ghrelin hormone
secreted by gastric mucosa , stimulating appetite
- high ghrelin levels when stomach empty
- ghrelin levels decline as stomach fills because the stimulation of stomach stretch receptos cause sense of satiation and declines hunger
grrrr hungry
what are the primary mechanisms of heat transfer
radiation - infared rays/waves, more than 50%
convection- heat transfer from heat circulating around body to air, ~15%
evaporation- heat loss through water (sweat) or the air we breathe out, ~20%
conduction- direct transfer of heat by physical contact,
body’s responses to high body temperature
denaturing (changing its structure) proteins leading to cell damage
- depresses neurons
what temperature can death occur from
Death can occur from extreme high or low temperatures
body’s responses to low body temperature
loss of muscle control + cardiac arrest
normal body temp is
98.6 F or 37C
and this is optimal for enzyme activity
do tissues tolerate decreased or increased temperatures better?
decreased
