Bio 161- Digestive System Final

pathway of food thru the digestive system

mouth, pharynx, esophagus, stomach, small int, large int, rectum, anus

4 layers of the digestive tract (outermost to innermost)

serosa, muscularis, submucosa, and mucosa

mucosa

innermost of digestive tract. produces mucus for protection, produces digestive enzymes

submucosa

loose connective tissue, contains blood vessels, lymph vessels, and nerves

muscularis

2 layers of smooth muscle (circular, longitudinal) move food along GI tract

serosa

outermost, part of peritoneum, secretes lubricating fluid

role of mouth in digestion

begins mechanical, and chemical digestion

roof of mouth seperates nasal cav from oral cav (hard palate- bone, and soft- muscle), ends in uvula

3 pairs of salivary glands secrete saliva

teeth, mechanically break down food

tongue- assists in mech breakdown, forms bolus

salivary amylase begins ____ digestion

carbohydrate

lysozyme is an _______ enzyme

antibacterial

mouth and nasal passages lead to _____

pharynx

esophagus

pharynx opens into esophagus and trachea

function of stomach

stores food, starts protein digestion, does not absorb nutrients

3 muscle layers in stomach

circular, longitudinal, and oblique

chyme

mixture of food and gastric juice

pyloric sphincter

only small amount of chyme enters small int at a time

in the small int, digestion is _____ and nutrients are _____

completed, absorbed

pancreas

secretes pancreatic juice (digestive enzymes) into duodenum through pancreatic duct

pancreatic amylase

digests carbohydrates

trypsin

digests protein

lipase

hydrolyzes fats in glycerol and fatty acids

bicarbonate

neutralizes acidic chyme

mucosa contain fingerlike projections called

villi

pancreas is also an endocrine gland and secretes ___ when blood glucose levels rise

insulin

type 1 diabetes

not enough insulin, juvenile onset

type 2 diabetes

body cells are insulin resistant, adult onset

A cells secrete _____, B cells secrete _____

glucagon, insulin

insulin secreted when

blood glucose levels are high (after a meal)

glucagon secreted when

blood glucose levels low

the structural and functional units of the liver that filter blood

lobules

functions of liver

stores vitamins

blood glucose homeostasis

produces plasma proteins

regulates blood cholesterol

produces bile

functions of gal bladder

stores bile

does gal bladder create bile

no

secretion of digestive juices controlled by NS and digestive hormones

neural (salivate when see/smell food), hormones: gastrin, secretin, CCK

gastrin

secreted by stomach in response to meal rich in protein: increased secretions of gastric glands

secretin

secreted by duodenum (release stimmed by HCI (in chyme))

cholecystokinin (CCK)

released by duodenum when proteins/fats are present

structures of large intestine

cecum, colon, rectum, anal canal

functions of large int

no digestion/digestive enzymes

does not absorb nutrients, except vitamins

absorbs water

absorbs vitamins produced by intestinal flora

forms/gets rid of feces

defecation reflex

rids body of feces

how does defecation reflex occur

peristalsis moves feces into rectum

stretching rectal wall initiates nerve impulses to spinal cord

rectal muscles contract and sphincters relax= feces exit thru anus

internal anal sphincter _____ muscle. external anal sphincter _____ muscle

smooth, skeletal