chapter 23 digestive system

Digestive System consists of

alimentary canal and accesory organs

Accessory organs

teeth, tongue, salivary glands, liver, and pancreas

Alimentary canal

conists of mouth, pharynx, esophagus, stomach, small intestine and large intestine.

Liver

makes bile

Gallbladder

stores bile

Pancreas

makes digestive enzymes needed chemical digestion

Digestive processes occurs in the ___

alimentary canal

Ingestion

foods enters the alimentary canal

mechanical digestion

physical means of breaking food

example of mechanical digestion

chewing, churring, and segmentation

chemical digestion

uses digestive enzymes that hydrolyze nutrients

hydrolsis

chemical digestion

Propulsion

food is pushed down the alimentary canal.

Example of propulsion

swallowing, perstalisis (moves food in digestive system), haustral (slow unncordinated movements.)

absorption

Nutrients that enters the blood vessel

Elimination

removal of solid wastes

Most of the alimentary canal has 4 layers

Mucosa, Submucosa, Muscularis externa, and Serosa

Mucosa

Mucous membrane lining (secretion, absorption, and dislodge of trapped food)

Submucosa

contains submucosal nerve plexus

muscular externa

contains the myentric nerve plexus.

(it also has smooth muscle, paraistalis, and segmention)

serosa

serous membrane visceral peritmeum covers the outside of the alimentary canal

Musculation externa

Can produce different movements by changing the pattern of smooth muscle contraction

Perstalis

propulsion

segmention

Mechanical digestion in the small intestine

There are 3 peritoneal folds of the serosa

Greateromentum, Lesser momentum, Messentery, Liver

Greater omentum

fatty apron dropes over the small intestine contains adipose tissue

lesser omentum

Attatches the stomach and doudneum to the liver (long term energy)

Messentery

Attatches the small intestine to the back body wall

liver

detoxification hepatic portal that absorbs nutrients to the liver

The entric nervous system

the nervous systems in the walls of alimentary canal.

contains 100 million neurons.

The gut brain- exters instrinsic from inside control over digestion

consists of sub mucosal nerve plexus and the my centric nerve plexus.

Submusocal nerve plexus

stimulates secretion of mucosa nerve

mycentric nerve plexus

stimulates the movement of pertstalis and segmentation

ANS

exerts extrinsic control of the digestive system

The mouth and pharnyx

uses degulation (swallowing) for proplusion

the esophagus

Uses peristalis for propulsion

Deglution

mouth, tongue, pharynx, Ulva, larynx, epiglottis

Stomach

has the largest cavity (lumen) of the gi tract.

• used to store food for several hours

• protein digestion begins here

The gastric gland secretes

HCL, Pepsinogen, Intrinsic Factor

HCL

Kills bacteria and dentures protein

Pepsinogen

inactive protein digestive enzyme

intrinsic factor

Chemical needed for vitamin B-12 absorption

Zygmogen

inactive protein ex: Pepsionegen

Goblet Cell

Secrete mucus

Highly regenrative

rapid cell division

Protections of the stomach

zymogen, goblet cells, highly regenerative

The Small Intestine

Longest part of the alimentary canal.

has 3 parts in (order) 1. Duodenum (10 inches long) 2. Jujunum (8 feet long) 3. Illeum (10 feet long)

Chemical digestion and complete absorption of all nutrients completed here

segmentation and peristalsis occur here.

There 3 accessory structures with ducts into the dudoneum of small intestine

Liver, gallbladder, and pancreas

bile

Bile salts (ensulfying fats) bilepigament, and chlocestrol

1. Duodneum

Making region

2. Jujunum

most of the chemical digestion and absorption happen here

3. Illeum

Specialized absorption of vitamin B-12 and bile salts and bike insteric factor for stomach

The large intestine

Has Bacterial flora

Prepares the solid wastes to be eliminated from the body.

Uses haustral contractions for propulsion.

Colon consists of 3 parts. 1 ascending colon, 2 transverse colon 3 descending colon

______ is completed in the small intestine

Chemical digestion

carbohydrate digestion

begins in the mouth makes amylase

protein digestion

begins im the stomach denatured by HCL

pepsin, trysin, chymotrypsin, and carboxypeptidase

made in the pancreas

Lipid digestion

(emuslfied by bilesalts) makes lipase which is made by pancreas

Nucleic Acid Digestion

deoxyribonuclease- breaks down DNA, Ribonuclease- breaks down RNA both are made by pancreas.

Liver

makes bile

detoxification

interconversation of nutrients