A&P final: digestive

digestion

process by which food substances are changed into forms that can be absorbed through cell membranes

ingestion

taking food into the mouth

movement of food

passage of food along the gastrointestinal tract

absorption

the passage of digested food from GI tract into bloodstream for distribution to cells

defecation

the elimination of undigested material from GI tract

alimentary canal

extends from the mouth to the anus

alimentary canal order: mouth to

pharynx

alimentary canal order: pharynx to

esophagus

alimentary canal order: esophagus to

stomach

alimentary canal order: stomach to

small intestine

alimentary canal order: small intestine to

large intestine

accessory organs release

secretions into alimentary canal that help digest food

mucosa

innermost; surrounds lumen

mucosa is composed of

epithelium + CT

Epithelium in mucosa extends into

lumen; which creates villi that increases surface area

mucosa contains glands that secrete

mucosa

submucosa

beneath mucosa

muscularis

two layers of muscle

layer of muscle comes first

circular muscle layer

circular muscle layer is around

submucosa

layer that comes after circular muscle layer

longitudinal layer

longitudinal layer is around

circular layer

function of muscularis

movements of food through canal

serosa

outermost layer

serosa is made up of

visceral peritoneum

function of serosa

lubrication

intestinal peritoneal extensions

mesentary

suspend the length of the intestine within abdominal cavity

mixing

mechanical digestion

movements of the tube

food+digestive juices+mucus

peristalsis

accomplished by movements of longitudinal muscle layer

propelling action

sphincter muscles

important role in movements throughout the GI tract

sphinctor

a strong circular muscle which prevents regurgitation of food

parasympathetic in digestion

activates digestion

sympathetic in digestion

slows digestion

submucosal plexus

controls secretions

myenteric plexus

controls peristalsis

oral cavity and buccal cavity refer to

mouth

mouth is adapted to

receive food and start mechanical and chemical digestion by chewing and mixing food with saliva

salivary glands secrete

saliva

salva binds

food together and begins chemical digestion of polysaccharides by the enzyme salivary amylase

parotid

largest lies over master, mostly serous cells

submandibular

floor of mouth lateral, mix of serous and mucous cells

sublingual

floor of mouth medial, mostly mucous cells

each salivary gland is composed of 2 types of cells

mucous cells; serous cells

mucous cells secrete

mucus

serous cells secrete

watery substance containing enzyme salivary amylase

pharynx

throat

function f pharynx

passageway of food into esophagus

esophagus

passageway for food from pharynx to stomach

location of esophagus

mediastinum behind trachea goes through diaphragm at esophageal hiatus

movement of food

gravity

peristaltic waves from esophagus meet

gastrosophageal sphincter muscle

gastric

stomach

stomach functions to

mix bolus into chyme and begin the chemical breakdown of proteins

stomach contains

extra oblique layer in muscularis

pyloric region

near duodenum

pyloric sphincter muscle lies between

pylorus and duodenum

macroscopic rugae

mucosal folds; thick

microscopically rugae are formed by

gastric villi and gastric pits

gastric villi

project into the lumen; tight

gastric pits

located between gastric villi

gastric glands

located along these gastric pits

gastric juice

secreted by these gastric glands

mechanical digestion

churning

chemical digestion of proteins

gastric juice

gastric secretion is composed of

mucus

function of digestive enzyme pepsin

protein digestion

function of hydrochloric acid

denatures proteins

kills microbes in food

function of intrinsic factor

aids absorption of Vitamin B12 needed for erythropoiesis

functions of gastrin

regulatory hormone

types of gastric cells

mucous

chief

parietal

G-cells

chief cells secrete

pepsin

parietal cells secrete

HCL & intrinsic factor

G-cells secrete

gastrin

parasympathetic in gastric secretion

increases gastric secretion

sympathetic in gastric secretion

decreases gastric secretion

gastric

increases gastric secretion

cholecystokinin

decreases gastric mobility

cephalic phase

increased parasympathetic due to sight, taste, smell, and thought of food

gastric phase

stretch of stomach wall increases gastrin secretion, which increases gastric secretions

pH changes alter gastrin release

gastric absorption

salts, water, lipid-soluble drugs, and alcohol

chyme=

mixing of bolus of food+gastric joice

peristaltic waves of stomach push chyme toward

pyloric sphincter; relaxes and food moves into duodenum a little at a time

structure of pancreas

shrimp-like with head in concave curve of duodenum; tail extends to the left of the spleen

endocrine cells produce

hormones glucagon and insulin

most cells in pancreas make up

pancreatic acini which produce pancreatic juice

pancreatic juice secretes into

pancreatic duct which leads to duodenum

pancreatic juice contains four classes of enzymes that

break down the four ingested organic macromolecules

pancreatic amylase

disaccharides

pancreatic lipase

break down fats

proteinases

break down proteins

duodenum fills with

acidic chyme

secretin is related from

intestinal wall

secretin stimulates the release of

bicarbonate rich pancreatic juice into duodenum

cholecystokinin activation occurs when acid is

neutralized

signals cholecystokinin release

proteins and fats

cholecystokinin stimulates release of

enzyme rich pancreatic juice into the duodenum

hepatic

liver

digestive function of liver

emulsification of fats

each lobe of liver is made of

hepatic lobules