Chapter 3 Flashcards
Digestion
- process of breaking down food into components small enough to be absorbed
absorption
- process of taking substances into interior of body
gastrointestinal tract
- hollow tube
- mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus
transit time
- time it takes food to pass length of gi tract
functions of gi tract
- ingestion - softening of food
- transport - rate varies
- secretion - enzymes, acid, bile, mucus
- absorption - of end products of digestion
- elimination
salivary glands
- moistens food
- supplies enzymes
gallbladder
- stores and secretes bile
- bile pH ~7-7.7 (alkaline)
pancreas
- secretes bicarbonate (alkaline) secretes enzyme
mouth
- mechanical breakdown through teeth
- enzymes: amylase-carbs (makes starch taste sweet), lingual lipase-fat
- saliva - moistens food for swallowing
esophagus
- transports food bolus from mouth to stomach
epiglottis
- covers passage to lungs when swallowing
pyloric sphincter
- smooth muscle at junction between pylorus of stomach and duodenum of small intestine
- acts as valve to control flow of digested food from stomach to intestine
duodenum
- proximal (upper) part of small intestine
- most digestion occurs in this part
jejunum
- middle part of small intestine
- absorbs digested nutrients
ileum
- distal part of small intestine
- absorbs digested nutrients
chyme
- thick semi-fluid mass of partly digested food that is passed from stomach to duodenum
- both physically and chemically softened food
peristalsis
- physical movement
- waves of muscular contractions
- longitudinal muscles relax
stomach: every 2s
small intestines: ever 4 s
large intestines: slower
stomach
- hydrochloric acid: preps protein for digestion, activates enzymes (pepsinogen to pepsin)
- pepsin: begins protein digestion
- gastric lipase: some fat digestion
- gastrin: stimulates gastric secretions and movement
- water
- mucous
- intrinsic factor
illeum
- intrinsic factor - needed for absorption of vitb12
digestive sectretions
- mucus: viscous materail produced by globlet cells, moistens, lubricates, protects gi tract
- enzymes: protein molecules that speed chemical reactions, not changed during reactions
chemical breakdown
- enzymes (proteins) catalyze reactions, end in ase - ex lipase
- hydrolysis: if water used to break molecule
esophageal sphincter
- prevents reflux of stomach content that causes heartburn
- gerd and ulcers
sphincter of oddi
- controls amount of bile and pancreatic secretions into small intestine
ileocecal sphincter
- prevents large intestine content from backing up into small intestine
intrinsic factor
- if a protein that binds ingested vitamin b12; it enables b12 to be absorbed by the intestine
- produced by parietal cells
without intrinsic factor
- allows b12 to be absorbed in ileum
- vitb12 needed to produce red blood cells
- can cause pernicious anemia: wekaness, cns damage, psychological disorders
age and b12
- absorption decreases with age
antacids and b12
- not enough stomach acid may inhibit b12 absorption
gi tract role in immune function
- protects body from infection
- limits absorption of toxins and pathogens
microbiota
- 10-100 trillion symbiotic microbial cells in each person
- mostly bacteria in gut
small intestine absroption
- folds, villi, microvilli expand absorptive surface
- most nutrients absorbed hiere
digestion of fat in small intestine
- primary site of fat digestion
- cck released from duodenal cells stimulates pancreas to release pancreatic lipase
- cck also stimluates the relase of bile
- bile helps emulsify fat, which increases surface area of food to aid action of lipase
- pancreatic cplipase is relased to facilitate lipase action
- fat is broken into monoglycerides and fatty acids
- lecithin from gall bladder ans protien colipase (aids lipases attachment to lipid)
absorptive mechanisms
- passive diffusion
- facilitated diffusion
- active transport
metabolic pathways
- series of reactions to transform food into final product that can be used by body
catabolic reactions
- release energy trapped in chemical bonds
- energy converted to atp
alternate feeding methods
- enteral or tube feeding: nutrition enters gut
- TPN: total perenteral nutrition, doesnt enter gut, ex. by blood stream
probiotics
- bacteria or yeast
- aid digestion
- alive
prebiotics
- form of fiber
- from food
diverticulosis
- pouches along colon
- high fiber diet reduces formation
- western diet affliction
GERD
- gastro-esophageal reflux disease
- reduced by smaller meals, less fat
- use of strong antiacids linked to hip fracture
irritable bowel syndrome
- can result in malabsorption of nutrients
- early diagnosis can result in no long term problems
- fodmap diet effective
colorectal cancer
- need high intake of vegetables, fruit, folate, ca, vitd
gas
- smell due to sulfur
- not bad
peptic ulcers
- bacterial cause
- h pylori secretes protective enzyme to survive in stomach
functional dyspepsia
- chronic pain in upper abdomen for unknown reason
- once cause known its no longer functional dyspepsia
chron’s disease
- causes inflammation on lining of digestive tract
- can lead to abdominal pain, severe diarrhea, fatigue, weight loss, malnutrition, death
ulcerative colitis
- causes inflammation of lining of large intestines only
- innermost lining of colon
effects of chromic digestive disorders
- failure to absorb nutrients: osteoperosis, nutritional deificiencies, eventual acute illness, can cause death
choldren: failure to grow, compromised immune systems, deficiencies more pronounced during growth
cholecystitis
- inflammation of gall bladder
- cuaes: blockage of cystic duct by gallstones. high fat, low fiber diet
- prevention: slowly lose weight (1-2lbs/week), diet high in fruit, veg, whole grains
