Digestive Flashcards
what is digestion
process of mechanical and chemical breakdown of food into subunits small enough to be absorbed into body (nutrients)
nutrients
substances essential for growth and maintaining life
main functions of digestive system
breakdown, storage, absorption, elimination of undigested food
macro-nutrients
required in large amount
ex) fat, protein
micro-nutrients
required in small amount
ex) vitamins, trace elements
essential nutrients
cannot be synthesized by animal, must be acquired from food
how many essential amino acids are there (human)
9
how many essential fatty acids are there (human)
2
how many essential vitamins are there (human)
13
examples of fat soluble vitamins
A, D, E, K
examples of water soluble vitamins
B, C, folic acid
monosaccharide
absorbable unit
glucose, fructose, galactose
disaccharides
more commonly found in food
sucrose, lactose
polysaccharides
chains of interconnected monosaccharides
starch, glycogen
cellulose
most abundant organic molecule
protein composition
various combinations of amino acids held together with peptide bonds
bulk of dietary fat/lipid:
tryglyceride
what do triglycerides break down into
glycerol + fatty acids
what do nucleic acids break down into
nucleotides > nucleosides > ribose + N-base
calorie (cal)
the amount of energy needed to raise the temperature of one gram of water by one degrees Celsius
how are bonds broken in digestive system
enzymatic hydrolysis
chemical reactions driven by specific enzymes
amylases, lipases, proteases, nucleases
intracellular digestion
cells take in food particles by endocytosis
extracellular digestion
takes place in digestive tract
gastrovascular cavity
functions in both digestion and distribution of nutrients
gastrovascular cavity vs tract
single opening vs separate mouth + anus
fluid feeders
ingest liquids containing organic molecules
suspension feeders
eat small particles of organic matter or small organisms suspended in fluids
deposit feeders
ingest small organic particles from solid matter that feeders live in or on
bulk feeders
consume large pieces of organisms or entire large organisms
tapeworms are ____ feeders
fluid > they have no digestive tract
they absorb nutrients by diffusion across their skin
gizzard
primitive form of stomach that uses stones to grind the food
typhlosole
finger-like projections in intestines that increase surface area
steps of grasshopper digestion
foregut, midgut, hindgut
foregut components
mouth, salivary glands, esophagus, crop, gizzard
midgut
where chemical digestion takes place
hindgut components
anterior, ileum, middle colon, posterior rectum, anus
canal of bird digestive tract
oral cavity, esophagus, stomach, gizzard, small intestine, large intestine
carnivore
digest animal product
herbivore
digest plant products
omnivore
digestive combination of plants and animals
carnivore digestive system
enlarged stomach, gastrointestinal tract is shorter, much smaller cecum
herbivore digestive system
long digestive tracts because it takes a long time to absorb nutrients from plant material
large cecum which helps breakdown plant material and cellulose
monogastric
have simple single-chambered stomach such as humans, swine, rabbits, horses
ruminants
have a four-chambered complex stomach > cow, goat, sheep
glands in monogastrics
secrete gastric juices that contain HCl
what forces chyme into small intestine
stomach muscles
4 chambers of a ruminant
rumen, reticulum, omasum, abomasum
rumen and reticulum
stores food with no secretion (mechanical breakdown)
omasum
absorbs water from food
abomasum
chemical digestion > acid + enzymes secreted
5 stages of GI tract digestion
mechanical processing
secretion of enzymes & digestive aids
enzymatic hydrolysis (food > molecular subunits)
absorption
elimination of undigested matter
Human GI tract pathway
mouth > pharynx > esophagus > stomach > small intestine > large intestine
accessory digestive organs
teeth, tongue, salivary glands, liver, gallbladder, pancreas
4 layers of GI tract
mucosa > submucosa > muscularis > serosa
^innermost to outermost
mucosa
innermost layer of GI wall surrounding lumen
secretes enzymes & hormones
submucosa
2nd innermost layer of GI tract
binds mucosa to muscularis
many nerves > enteric nervous system
muscularis
2nd outermost layer of GI tract
skeletal muscle and smooth muscle
serosa
outermost layer of GI tract
membrane of areolar connective tissue and simple epithelium
oral cavity
chamber that contains teeth & tongue, receives secretions from salivary glands
swallowing procedure
bolus is swallowed through pharynx and esophagus to stomach
epiglottis blocks trachea
peristalsis
involuntary contraction and relaxation of muscles of GI tract
peristaltic waves
coordinated contraction of circular and longitudinal muscles to move content from stomach to anus
chyme
mix of food, stomach acid & enzymes
gastric juices
contain HCl, gives stomach pH of 2, kills most bacteria in food
pepsin
begins digestion of proteins
gastric lipase
aids digestion of triglycerides
what does HCl in stomach do
does not digest food
breaks down the connective tissue of meat and proteins
what protects stomach wall from HCl
mucus
duodenum
first 25 cm of small intestine
jejunum
second portion of small intestine
ileum
last portion of small intestine
ileocecal sphincter
connects small and large intestines
walls of small intestine
covered in projections called villi, which host thousands of microvilli
villi
located on walls of small intestine, contain blood and lymphatic capillaries
role of small intestine
completes digestion, absorption of nutrients
liver secretions
bile that emulsifies fats
gallbladder role
stores bile, which is eventually secreted in duodenum
chylomicrons
small droplets of triglycerides covered by a hydrophilic protein coat > taken up by lymph vessels and transferred into blood stream
hepatic portal vein
joined together capillaries and veins coming from small intestine
content of large intestine
cecum, appendix, colon, rectum
main function of large intestine
absorbing water and other ions
500 species of ____ live in intestines
bacteria
