The Digestive System

quizlet sucks

mechanical digestion

physical breakdown of food

chemical digestion

chemical breakdown of food

layers of the alimentary canal

mucosa, submucosa, muscular layer, serosa

mucosa layer components

epithelium, connective tissue, smooth muscle

folds in the mucosa layer

lumens

purpose of lumens

increase surface area

glands in alimentary canal secrete

mucus and digestive enzymes

mucus function

protect tissues

submucosa layer components

loose connective tissue, glands, blood vessels, lymphatic vessels, nerves

function of submucosa

nourishes tissues and carries away absorbed materials

muscular layer components

inner and outer coat of smooth muscle

inner coat of smooth muscle

circular fibers that decrease diameter of canal

outer coat of smooth muscle

longitudinal fibers that shorten the canal

function of the muscular layer

provide canal movements

serosa layer components

epithelium, connective tissue

serosa layer is called

visceral peritoneum

serosa layer function

protect tissues, secrete serous fluid

function of serous fluid

lubrication

mixing movements

segmentation, muscle contractions are back and forth

propelling movements

peristalsis, circular fibers contract and push food down tube

mastication

mechanical digestion, mix food with saliva

cavity between roof of mouth and tongue

oral cavity

area in front of teeth and behind the cheeks/gums

vestibule

cheek components

skin, subcutaneous fat, muscle, stratified squamous epithelium inside

lip components

skeletal muscles, sensory receptors

lip color is from

blood vessels

tongue is covered by

mucous membranes

connects the bottom of the tongue to the floor of the mouth

lingual frenulum

tongue is mostly

skeletal muscle

function of tongue papillae

provide friction, taste buds

root of tongue is attached to

hyoid bone

root of tongue is covered by

lingual tonsils

tonsils are for

immunity

roof of oral cavity

palate

anterior portion of palate

hard palate

posterior portion of palate

soft palate

projection off the soft palate

uvula

tonsils in the back of the mouth

palatine tonsils

tonsils below the palatine tonsils

pharyngeal tonsils, adenoids

tonsils are removed if they block the

nasal passage

first set of teeth

primary teeth, deciduous

second set of teeth

secondary teeth, permanent

how many deciduous teeth

20

how many permanent teeth

32

gums are called

gingiva

function of teeth

mechanical digestion, increases surface area of food

top part of tooth

crown

bottom part of tooth

root

enamel covers the tooth and is made of

calcium salts

bulk of tooth behind enamel

dentin

cavity inside the dentin

pulp cavity

pulp cavity contents

blood vessels, nerves, connective tissue

secures the tooth to the jaw

periodontal ligament

salivary glands secrete

saliva

function of saliva

moisten and bind particles, begin carb digestion

salivary gland cells

serous and mucous

serous cells produce fluid that contains

salivary amylase

salivary amylase function

splits starch and glycogen molecules into disaccharides

mucous cells secrete

mucus

secretion of saliva is triggered by \_____ when food is sensed

parasympathetic impulses

parotid glands

serous cells, salivary amylase

submandibular glands

serous and mucous cells, salivary amylase and mucus

sublingual glands

mucous cells, mucus

parts of the pharynx

nasopharynx, oropharynx, laryngopharynx

stage 1 of swallowing

food mixed with saliva

bolus is formed

stage 2 of swallowing

sensory receptors trigger swallowing reflex

uvula rises

epiglottis closes top of larynx

peristalsis begins

breathing stops

stage 3 of swallowing

peristalsis moves food to the stomach

esophagus passes through the diaphragm via

esophageal hiatus

this structure at the point where esophagus meets the stomach

lower esophageal sphincter

fibers of the lower esophageal sphincter

circular smooth muscle

fibers of the lower esophageal sphincter are relaxed by

peristalsis

fibers of the lower esophageal sphincter remain contracted to prevent

regurgitation

stomach has folds called

rugae

digestion in the stomach

food mixes with gastric juice, protein digestion begins, some absorption

part of the stomach near the lower esophageal hiatus

cardia

bulge at the top of the stomach

fundus

main part of the stomach

body

last section of the stomach

pylorus

parts of the pylorus

antrum and canal

part at the end of the pyloric canal that controls gastric emptying

pyloric sphincter

NOTE stomach mucous membrane is thick

the numerous gastric pits are the openings to the longer

gastric glands

gastric glands have three types of cells

mucous, chief, parietal

gastric gland mucous cells

close to the opening of the gland, secrete mucus

gastric gland chief cells

deeper part of the gland, secrete digestive enzymes

gastric gland parietal cells

deeper part of the gland, secrete hydrochloric acid solution

most important digestive enzyme

pepsin

pepsin is secreted by chief cells in the form of inactive enzyme called

pepsinogen

pepsin breaks down and turns into pepsin when it comes in contact with

hydrochloric acid

pepsin function

breaks protein into popypeptides

viscous alkaline secretion that covers the inside of the stomach wall and prevents it from digesting itself comes from

mucous cells

parietal cells secrete \___ that helps the small intestine absorb B12 vitamin

intrinsic factor

gastric secretion is controlled by

neurons and hormones

sensing food stimulates sympathetic impulses from the vagus nerves to stimulate the release of

ACh

ACh causes the gastric glands to secrete more

gastric juice

acid from the stomach that enters the small intestine triggers impulses that inhibit the secretion of

gastric juice

proteins and fats in the small intestine cause intestine wall to release

CCK

CCK is called

cholecystokinin

CCK is a

peptide hormone

CCK function

decreases gastric motility