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nutrition as a science
how living organisms obtain and use food to support bodily porcesses
RDs
licensed nutrition professionals
nutritional sciencetist
conduct and evaluate nutrition research
they work in academic and social nutrition science
nutrients
something used by the body for energy and maintenance and regulation of chemical precesses
essential nutrients
must be obtained in the diet
nonessential nutrients
do not need in the diet
body can make enough to satisfy physiological requirements
conditionally essential nutrients
only needed in some circumstances, usually nonessential nutrients
protein
macronutrient, 4 kcal/g
CHO
macronutrient, 4 kcal/g
lipids
macronutrient, 9 kcal/g
alcohol
7 kcal/g
micronutrients
vitamins and minerals
phytochemicals
from plants, substances that offer some benefit to human health
zoonutrients
from animals, substances that are thought to have a benefit to human health
functional foods
essential nutrient, phytochemical or zoonutrients that is thought to have a benefit to human health
bomb calorimeter
measures caloric content
scientific method
observe, hypothesize, test
cause and effect (causal relationships)
when a alteration in one variable causes a change in another
correlation
when a change in one variable is related to a change in another
positive correlation
an association between factors where and changes are similar/related
-watching tv and obesity
negative correlation (inverse)
changes in variables are in opposite direction
pseudoscience
ideas, claims, practices that are presented as scientific and credible but lack evidence and are not based on the scientific method
-cherry picked data
-lack reliability
atoms
fundamental units of the world around us
protons, newtons, electrons
cations
ions with a positive charge
anions
ions with negative charge
element
substance made of one type of atom
how many elements total
92
how many essential elements
20
most common are C, O, H, N, Ph
macromolecules
large molecules of many atoms
effect of acid-base in the body
diseases can disrupt this in the body, very bad
acid base balance
water molecules can dissociate into their ionic compounds (H+ and OH-)
pH scale
based on ionization of water
0-14, acidic-basic
more H+
more acidic
more OH-
more basic
cell membrances
selectively permeable
passive transport
no ATP
active transport
need ATP
simple diffusion
substances more down concentration gradient
faciliated diffusion
substances more down concentration gradient with help to protein channel
osmsis
movement of water from area with low solute concentration to high solute concentration until balance is reached
carrier mediated transport
substances move from up concentration gradient with help of transport protein
vesicular mediated transport
large molecules move into or out of the cell against gradient enclosed by a vesicle
endocytosis
cell membrane surrounds extracellular substance and releases it into the cytoplasm
exocytosis
intracellular products are enclosed in a residue and released outside the cell
buffer
substance that releases or binds to H+ to resist pH change
condenstation
joining of molecules with creates water
hydrolysis
use of water to split compounds
chemical bonds
attractive force between atoms formed by transfer or sharing of e-
molecule
substances held together by chemical bonds
oxidation
loss of electrons, becomes more positive
reduction
gain of electrons, becomes more negative
oxidation-reduction
one molecule gains e- and another loses e- at the same time
GI tract
tube from mouth to anus
GI organs
mouth, esophagus, pancreas, stomach, SI and LI
GI accessory organs
salivary glands, pancreas, liver, biliary ducts, gallbladder
digestion
physical and chemical breakdown of food into nutrients
absorption
passage of nutrients through the lining of the GI tract into the blood or lymphatic fluid
egestion
elimination of waste from the body
mucosa
innermost layer of the Gi tract, made of epithelial cells
makes GI secretions
needs constant blood flow and nutrient supply due to fast cell turnover rate
GI secretions
substances released by the digestive organs to facilitate the digestion process
submucosa
layer between the mucosal lining and muscle
contain blood vessel, lymphatic vessels, has nerve innervation
muscularis
smooth muscle, contains nerves that help with contraction and relaxation
serosa
connective tissue enclosing the GI tract
secretes fluid that lubricates to digestive organs
transit time
24-72 hours from mouth to anus
Gi motility
mixing and propulsive movements of the GI tract that more chyme
segmentation
moving of contents back and forth in a small region
penstalsis
waves of contracts that move contents in a forwards direction
digestive enzymes
biological catalysts
create hydrolysis
exocrine cells
produce and secrete into ducts that empty directly into the lumen of the GI tract
goblet cells are an example
acinar cells
in the pancreas
produce and secrete enzymes into the SI
enteric nervous system
neurons within the submuscosa and GI muscle of the digestive tract
controls smooth muscle, release of GI secretion
receives input in the sensory receptors in the GI tract
sensory receptors
monitor condition and changes in pH
chemoreceptors
responds to chemical stimulus
mechanoreceptors
responds to pressure, stretching, mechanical stimulus
endocrine glands
produce and releases hormones into the blood
causes changes in motility and GI secretions
GI hormones
secreted by mucosal lining, regulate GI motility and secretions
can communicate with the appetite center in the brain
secretin
produced in the Si
inhibits GI motility
stops secretion of gastric juice
stimulated release of pancreatic juice
stimulated by arrival a chyme in the duedemum
ghrelin
produced by the stomach stimulates hunger in the brain
released when stomach is empty
gastric inhibitory peptide
produced in the Si
stop gastric emptying
stimulus is when food flows from the stomach to the SI
gastrin
produced in the stomach
stimulates GI motility
secretes gastric juice, increases gastric motility
stimuli are= food in the stomach, stretching of the stomach, alcohol, caffeine, smell.taste of food
cholestokinin (CCK)
produced in the SI
stimulates gallbladder to contract and release bile
stimulates release of pancreatic enzymes to SI
stimuli is the arrival of partially digested protein and fat from the duodenum
glucagon-like peptide (GLP-1)
produced in the SI and LI and stops gi motility, slows gastric emptying, reduces appetite
stimuli is the flow of food from the stomach to SI
cephalic phase
CNS response to sensory stimuli (taste, smell, sight)
before food enters the GI tract it increases GI motility and release of GI secretions
gastric phase
food in stomach
increase in GI motility and release of Gi secretions
intestinal phase
chyme enters the SI
decrease in gastric motility and decrease in gastric juice secretion
mastication
chewing and grinding of food in the mouth by the teeth
bolus
soft, moist, chewed food
saliva
released by the salivary glands, moistens food and starts digestion of carbs
contains water, mucus, enzymes and antibacterial agents
phanyx
the area in the back of the mouth in between the oral and nasal cavity
voluntary swallowing
in the mouth
involuntary swallowing
in the pharynx
bolus continues down the esophagus
dysphagia
difficulty swallowing
caused by skeletal muscle disorders
esophagus
passageway from the pharynx to the stomach
ends at the gastroesophageal sphincter
GERD
weakening of the gastroesophageal sphincter causes acid reflux
stomach
3 regions- fundus, body, antrum
starts with the gastroesophageal sphincter and ends with the pyloric sphincter
stores food temporarily, produces gastric secretions, mixes food
rugae
folds of the inner stomach, allows for stomach stretching
empty stomach capacity
¼ cup
full stomach capacity
16 cups
gastric pits
infoldings of the muscoal linging that hold endo and exocrine cells
gastric juice
digestive fluid made by exocrine cells
made of water, enzymes, mucus, and intrinsic factor