nutrition, metabolism, and body temp (ch 23) Flashcards
what is a nutrient
a substance in food for growth, maintenance, and repair
what are major nutrients
the bulk of ingested food
major nutrients
carbohydrates, fat, protein
what are micronutrients
things required in small amounts
micronutrients
vitamins, minerals
uses for nutrients
metabolic fuel
cell structure and molecular synthesis
energy value is measured by
kcal = Calorie = heat energy needed to raise 1L H2O by 1C
food groups
fruit, vegetables, grain, protein, dairy, oil
what converts molecules into those needed to live
the liver
what are essential nutrients
the approximately 50 molecules that the diet must provide - cannot be synthesized by the liver
dietary sources of carbohydrates
primarily plants (starch, sugars, fiber)
some animal sources (glycogen)
starches are
complex carbs - lots of sugars strung in a long chain
sugars are
mono and disaccharides
fibers are
not digestible because we lack the necessary enzymes (insoluble - cellulose, soluble - pectin)
carbohydrate examples in food
starch - vegetables and grains
sugars - milk, fruit, cane sugar
insoluble fiber - green vegetables
soluble fiber - fruits, oats
carbohydrate use in body
glucose - major energy fuel used by cells to assemble ATP
which cells can only use glucose for energy
neurons and RBCs
what happens to excess glucose
it is converted to glycogen or fat and stored
what can be converted to glucose
fructose and galactose
recommended intake of carbohydrates
45-65% of total caloric intake, mostly complex (fruits, vegetables, grains)
highly refined carbohydrates can cause
obesity, chronic disease, increased risk of type 2 diabetes
difference between saturated and unsaturated fats
saturated - lack of double bonds, animal sources (meat/dairy), solid at room temp
unsaturated - at least one double bond, plant oil/nut sources
where can cholesterol come from
egg yolk, meats, organs, shellfish, milk products
ALSO, liver makes around 85% of necessary cholesterol
what are essential fatty acids
fatty acids that cannot be made by the liver from other fats
essential fatty acid examples
linoleic and linolenic acid (found in most veg oils)
function of lipids (general)
major fuel source for liver and muscle cells
function of phospholipids
component of cell membranes
function of adipose tissue
energy stores, cushioning
function of prostaglandins
inflammation, smooth muscle contraction
function of cholesterol
important for membranes, bile, and hormones
dietary recommendations for fats per the AHA
fats - 30% or less of total caloric intake
cholesterol - less than 200 mg/dL in blood
what are complete proteins
proteins containing all essential amino acids (animal sources)
what are incomplete proteins
proteins that do not contain all essential amino acids (plant protein)
can the body produce essential amino acids
no
how to get all essential amino acids without animal products
combine grains/cereals (grasses) with legumes (beans)
which proteins are used as structural materials in the body
insoluble fibers (collagen, elastin, actin, myosin)
which proteins are used as functional molecules in the body
soluble proteins (enzymes, hormones, antibodies)
protein can be used as ______ when there is not enough ___________ available
an alternative energy source, carbohydrates or fats
all amino acids must be present for _______
adequate protein synthesis
all amino acids contain _______
nitrogen
positive nitrogen balance
when synthesis exceeds breakdown - to grow there needs to be extra amino acids
(occurs in instances of growing muscle, pregnancy, and kids)
negative nitrogen balance
when breakdown exceeds synthesis - growth does not occur (cases of starvation, sedentary individuals, elderly)
anabolic hormones such as GH and sex hormones
induce protein synthesis
adrenal glucocorticoids (released during stress)
catabolize/breakdown protein to use as fuel
dietary requirements for protein
needs reflect age, size, metabolic rate, nitrogen balance (but the typical American diet provides plenty of protein)
organic compounds of vitamins
carbon and hyrogen
functions of vitamins
helping body use nutrients
coenzymes (works with enzymes in chemical reactions)
non-food sources of vitamins
D - skin
B and K - synthesized by intestinal bacteria
A - converted from beta-carotene
characteristics of water soluble vitamins
all B vitamins, vitamin C
absorbed with water
not stored in body (goes quickly through urine)
B12 absorption requires
intrinsic factor (parietal cells to be secreted by stomach cells)
characteristics of fat-soluble vitamins
vitamins A, D, E, and K
stored in body, except for vitamin K
high levels are toxic
how is vitamin K produced
by bacteria in the large intestine
function of antioxidants/example
picking up electrons in the body, neutralize free radicals (vitamins C, A, E)
what are free radicals
chemicals with extra electrons that mainly damage proteins
minerals are
inorganic materials/ions, mainly metals
minerals required in moderate amounts/how much
greater than 200 mg/day of the following: calcium, phosphorus, sulfur, potassium, chlorine, sodium
minerals required in trace amounts
iron, fluorine, zinc, copper, iodine, maganese
function of mineral
working with nutrients to ensure proper body function
how is mineral toxicity prevented
uptake and excretion are balanced
function of calcium and phosphorus
needed for bones
function of iron
essential for heme in hemoglobin
function of iodine
necessary for T3/T4 thyroid hormone synthesis
sodium, chloride, and potassium are all
major electrolytes
metabolism is
biochemical reactions inside cells that involve nutrients (how we get energy)
types of metabolic reactions
anabolism - synthesis of large molecules from small (energy in)
catabolism - breakdown of complex structures to simpler ones (energy out)
examples of metabolic reactions
anabolism: amino acids –> protein
catabolism: food + O2 –> CO2 + H2O + energy
cellular respiration
the catabolism/oxidization of food to fuel, captures energy to form ATP from ADP + phosphate
phosphorylation
when a molecule gives a phosphate group to another, giving them the energy to perform cell activities that require energy
stages of metabolism in processing nutrients
digestion, absorption, and transport to tissues
cellular processing (in cytoplasm)
how is food oxidized for fuel
pairs of hydrogen atoms are removed from food step by step, then the pairs combine with oxygen to form H2O
types of cellular respiration
glycolysis, Krebs (citric acid) cycle, oxidative phosphorylation
oxidized vs reduced substances
oxidized - loses electrons or hydrogen, and energy
reduced - gains electrons or hydrogen, and energy
characteristics of redox reactions
catalyzed by enzymes (often require help from coenzymes)
characteristics/examples of coenzymes
acts as hydrogen or electron acceptors
ex: vitamin B derivatives (B3 niacin, B2 riboflavin), NAD+ (from niacin), FAD (from riboflavin)
substrate level phosphorylation
type of ATP synthesis in which high-energy phosphates are directly transferred to ADP
oxidative phosphorylation
more complex type of ATP synthesis, produces most ATP
oxidative phosphorylation process
direct (usually in cytoplasm) - energy is used to pump H+ across the inner mitochondrial membrane
indirect (mitochondria) - H+ flows back through ATP synthase membrane channel, energy is used to phosphorylate ADP
complete glucose catabolism requires three pathways
glycolysis
Krebs cycle
electron transport chain and oxidative phosphorylation
characteristics of glycolysis
10 steps, anaerobic, occurs in cytosol
glucose –> two pyruvates
produces ATP faster than aerobic respiration
yields far less ATP (1 glucose : 2 ATP)
glycolysis steps
if no oxygen present, NADH gives H+ back to pyruvic acid, reducing it to lactic acid
lactate leaves the cell and goes to the liver
may be converted back to glucose for release into blood or for storage as glycogen
characteristics of the Krebs cycle
occurs in the mitochondrial matrix
fueled by pyruvic acid
1 glucose : 2 pyruvic acid molecules (2 Krebs cycles)
Krebs cycle steps
pyruvic acid loses one carbon to form acetyl group
then combines with coenzyme A to form acetyl-coenzyme A
coenzyme A takes acetic acid to Krebs cycle
acetyl-coenzyme A combines with oxaloacetic acid to form citric acid
two carbons are removed as CO2 and energy is passed to ATP, NACH + H+, and FADH2
oxaloacetic acid is regenerated
characteristics of the electron transport chain and oxidative phosphorylation
directly uses oxygen
NADH + H+ and FADH2 have hydrogen
1 glucose : 30 ATP
electron transport chain and oxidative phosphorylation steps
hydrogen atoms combine with O2 to form H2O
released energy is given to ATP by oxidative phosphorylation
characteristics of lipid metabolism
greatest energy yield of the macromolecules
glycerol pathway - sugar enters glycolysis to Krebs
fatty acid pathway - chains broken off in two carbon fragments and enters the Krebs cycle
a lack of carbohydrate in one’s diet leads to
lots of acetyl CoA and ketones
characteristics of protein metabolism
proteins are continuously broken down and replaced - amino acids are recycled for new proteins or another compound, or oxidized for energy or converted to fat for storage
how are amino acids oxidized
first deaminated (NH2 removed), then most are converted to various chemicals of the Krebs cycle
most nitrogen waste is converted into urea by the liver and excrete in the urine
metabolic rate
total heat produced by chemical reactions and friction within the body
basal metabolic rate
minimum number of chemical reactions needed to live
what influences BMR
body surface area ration, age, gender, body temperature, stress, thyroxine (T3/T4)
at rest, how is heat produced
organs - heart, liver, brain, kidney
during exercise, how is heat produced
muscles
normal body temperature is
37C or 98F
why is a body temperature of 37C needed
optimal range for body enzyme activity (increased temperature denatures enzymes)
children under five have seizures at 41C
limit for life: 43C
tissues may tolerate ________
low body temperatures
core vs shell temperature
core temp - highest/most constant
shell (skin) temp - usually lower, fluctuates between 20-40C
mechanisms of heat exchange with the environment
radiation
conduction
convection
evaporation
radiation
heat exchange through infrared rays
conduction
heat exchange through direct contact
convection
heat exchange through air movement
evaporation
heat exchange through water converting into gas
______ heat loss accompanies ______ water loss
insensible
insensible vs sensible heat loss
insensible - lungs, mucous membranes, skin (sweat)
sensible - when body temperature rises and you sweat (aware)
the ______ region of the hypothalamus receives afferent input from ______
preoptic, peripheral (skin) and central (deep) thermoreceptors
after receiving afferent input, the hypothalamus initiates
involuntary heat-loss and heat-promoting activities
types of heat-promoting mechanisms
constriction of BVs in extremities and skin
shivering
increased metabolic rate via epinephrine and NE
chemical thermogenesis
adipose tissue thermogenesis
enhanced thyroxine release
types of heat-loss mechanisms
dilation of cutaneous BVs, increasing blood to extremities and skin
sweating
hyperthermia
increased core body temperature
characteristics of heat exhaustion
collapse usually after vigorous exercise
dehydration with decrease in BP
heat-loss mechanisms still functioning
heat stroke begins at a core body temperature of _____C
41
characteristics of heat stroke
positive feedback mechanism (makes issue worse)
sweat stops - skin hot and dry
organs damages through denatured proteins
if not corrected, can lead to coma or death
characteristics of a fever
controlled hyperthermia
macrophages release cytokines/pyrogens that cause fever
damaged tissues release prostaglandins that reset the hypothalamic thermostat
characteristics of hypothermia
low body temperature due to exposure
vital signs decrease
at core temperature of 30-32C, shivering stops
loss of judgement –> coma –> death at 21C by cardiac arrest
