digestive mouth - pancreas

functions of digestive system

take in food, break food down into nutrient molecules, absorb molecules into bloodstream, rid body of indigestible remains

digestion

mechanical and chemical breakdown of foods into forms that cell membranes can absorb

mechanical digestion

break down large pieces of food into smaller ones, but doesn’t change chemical composition

chemical digestion

use enzymes to break down food particles by changing them into simpler chemicals

what is the alimentary canal

muscular tube that runs from mouth to anus

what does the alimentary canal do

digest food and absorb fragments through lining into blood

what are the organs of the alimentary canal

mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus

what are the accessory digestive organs

teeth, tongue, gallbladder, digestive glands

what is the wall of the alimentary canal composed of

mucose, submucosa, muscularis externa and serosa

what is the mucosa layer

innermost layer, mucous membrane

what is the mucosa layer do

protection, secretion, absorption

what is the submucosa layer

connective tissue layer

what does the submucosa layer do

nourish surrounding tissue, transport absorbed materials

what is the muscularis externa layer do

muscle tissue

what does the muscularis externa do

movement of tube and its contents

what is the serosa layer

outermost layer

what does the serosa layer do

protection and lubrication

what are the 6 essential activities of processing food

ingestion, propulsion, mechanical breakdown, digestion, absorption, defecation

ingestion

eating

propulsion

food movement through GI

how do we move food through GI tract

swallowing and peristalsis

peristalsis

major propulsion method involves alternating contraction and relaxation

essential activity mechanical breakdown

chewing, mixing food and slavia, churning food in stomach

segmentation

local intestine constriction to mix food with digestive juicesd

igestion

catabolic steps where enzymes break down complex food molecules into chemical building blocks

absoprtion

digested fragments enter from GI lumen tract into blood or lymphd

defecation

excretion of indigestible substances via anus

what innervates the alimentary canal

submucosal and myentric plexus

what do parasympathetic impulses control

increase activity of digestive system

what do sympathetic impulses control

inhibit digestive actions

what do enteroendocrine cells do

secrete hormones to regulate GI organs and processes

peritoneum

membranes of abdominal cavity

peritoneal cavity

fluid filled space between 2 peritoneums

visceral peritoneum

external surface of most digestive organs

parietal peritoneum

membrane that lines body wall

what does the peritoneal cavity do

fluid lubricates mobile organs

what is mesentery

double layer of peritoneum that is fused back to back

what does mesentery do

hold blood vessels, lymphatics, nerves and organs in place and stores fat

what does splanchnic circulation include

arteries that branch off aorta to serve digestive organs

hepatic portal circulation

drain nutrient rich blood from digestive organ, deliver blood to liver for processing

enteric nervous system

link between digestive system and brain

enteric neurons

control GI motility and receive outside info to slow/raise digestion

what 3 concepts regulate GI activity

range of mechanical/chemical stimuli, effector of digestive activity are smooth muscle and gland, neurons and hormones control activity

how is activity provoked by range of mechanical/chemical stimuli

receptors located in GI wall respond to stretch, change in osmolarity, and presence of substrate

effector of digestive activity

receptors stimulate smooth muscles to mix and move lumen content

how do neuron and hormone control digestive activity

NS control intrinsic and extrinsic, hormones stimulate target cell to secrete/contract

intrinsic control

enteric NS

extrinsic control

autonomic NS

mouth

fist part of alimentary canal

mouth function

organ of speech and sensory reception

what are the associated organs of the mouth

mouth, tongue, salivary glands, teeth

cheeks

contain muscles for facial expression and chewingl

lips

sensory receptors judge temperature and texture of food

tongue

thick muscular organ that occupies the floor of the mouth

lingual frenulum

connect tongue to floor of mouth

papillae

projection that move food, contain tastebud

lingual tonsils

lymphatic tissue masses on root of tongue

palate has 2 distinct parts

hard and soft palate

hard palate:

form by palatine bones and palatine processes

soft palate

fold formed mostly of skeletal muscle, end in uvulau

uvula

fingerlike projection that faces downward from free edge of soft palate

palatine tonsils

lymphatic masses on side of tongue

pharyngeal tonsil

masses of lymphatic tissue in posterior wall of pharynx

tongue has 3 types of papillae

filiform, fungiform, vallate papillae

filiform papillae

provide friction (tingue portion)

fungiform papillae

scattered across tongue (bumps on tongue)

vallate papillae

form v shape row in back of tongue

saliva functions

cleanse mouth, dissolve food chemical for taste, moisten food, begin starch breakdown via amylase

where is most saliva produces

major salivary glands outside of oral cavity

what are the 3 major salivary glands

parotid, submandibular, sublingualp

parotid

ducts open into oral vestibule next to second upper molar

submandibular

duct opens at base of lingual frenulum

sublingual

duct open via 10-12 duct into floor of mouth

salivary gland composed of 2 types of secretory cell

serous cells and mucous cells

serous cell

produce water secretionm

mucous cell

produce mucous

what is saliva composed of

water (97-99%), slightly acidic, electrolyte, salivary amylase and lingual lipase

what gland keep mouth moist

minor

what gland are activated when ingested food stimulates receptor in mouth

major

what stimulation inhibits salivation

SNS

what do teeth do

break food particles down to smaller peices

how many teeth do babies have

20h

how many teeth do adults have

32 permanent

teeth are classified by

incisors, canines, premolars, molarsi

incisors

chisel shape for cutting

canines

fang teeth that tear or pierce

premolar

broad crown with round cusp to grind or crush

molar

broad crown, round cusps, best grinder

2 major regions of tooth

crown and root

crown is

exposed part above gingiva

root is

embedded in jaw bone

cement

calcified connective tissue

dentin

bonelike material under enamel

pulp cavity

surround by dentin

pulp

connective tissue, blood vessels, and nerve

root canal

pulp cavity extends to root

esophagus

flat muscular tube that runs from laryngopharynx to stomach

esophageal sphincter

surrounds cardiac orifice

esophageal sphincter function

keep orifice closed when food isnt being swallowed

function of esophagus

propulsion that starts with deglutition