digestivesystem 2012

8/12/2019 digestivesystem 2012

1/36

1

The Digestive System


2/36

2

Digestion

Processing of food

Types

Mechanical (physical)

Chew Tear

Grind

Mash

Mix

Chemical Catabolic reactions

Enzymatic hydrolysis

Carbohydrate

Protein

Lipid


3/36

3

Digestion

Phases

Ingestion

MovementDigestion

Absorption

Further digestion


4/36

4

Digestive System Organization

Gastrointestinal (Gl) tract (Alimentary canal)

Tube within a tube

Direct link/path between organs

Structures Mouth

Oral Cavity

Pharynx

Esophagus

Stomach Duedenum

Jejenum

Ileum

Cecum

Ascending colon

Transverse colon


5/36

5

Digestive System Organization

Descending colon

Sigmoid colon

Rectum

Anus

Accessory structures Not in tube path

Organs

Teeth

Tongue

Salivary glands Liver

Gall bladder

Pancreas


6/36

6

Anatomy of the Mouth and

Throat


7/36

7

Human Deciduous and

Permanent Teeth


8/36

8

Dorsal Surface of the Tongue


9/36

9

The Major Salivary Glands


10/36

10

Deglutition (swallowing)

Sequence

Voluntary stage

Push food to back ofmouth

Pharyngeal stage Raise

Soft palate

Larynx + hyoid

Tongue to soft palate

Esophageal stage

Contract pharyngealmuscles

Open esophagus

Start peristalsis


11/36

11

Deglutition (swallowing)

Control

Nerves

Glossopharyngeal

Vagus

Accessory Brain stem

Deglutition center

Medulla oblongata

Pons

Disorders Dysphagia

Aphagia


12/36

12

Esophagus

Usually collapsed (closed)

3 constrictions

Aortic arch

Left primary bronchus Diaphragm

Surrounded by

SNS plexus

Blood vessels

Functions

Secrete mucous

Transport food


13/36

13

Peristalsis and Segmentation


14/36

14

Esophagus

Sphincters

Upper

Lower

Abnormalities

Achalasia

Atresia

Hernia Barrets esophagus

Esophageal varices


15/36

15

Stomach

Usually J shaped

Left side, anterior to the spleen

Mucous membrane

G cellsmake gastrin

Goblet cellsmake mucous

Gastric pitOxyntic glandParietal cellsMakeHCl

Chief cellsZymogenic cells Pepsin

Gastric lipase


16/36

16

Anatomy of the Stomach


17/36

17

Stomach

Muscularis membrane :

Oblique

Circular

Longitudinal

Serosa membrane

Regions

Cardiac sphincter

Fundus Corpus

Antrum Pyloric


18/36

18

Stomach

Functions

Mix food

Reservoir

Start digestion of

Protein

Nucleic acids

Fats

Activates some enzymes

Destroy some bacteria

Makes intrinsic factorB12 absorption

Absorbs

Alcohol

Water

Lipophilic acid B 12


19/36

19

Small Intestine

Extends from pyloric

sphincterileocecal

valve

Regions Duodenum

Jejenum

Ileum

Movements Segmentation

Peristalsis


20/36

20

Small Intestine

Histology

Intestinal glandsIntestinal enzymes

Duodenal glandsAlkaline mucous

Paneth cellsLysozyme Microvilli

Lacteals

Plica circularis

Smooth muscle Lymphatic tissueGALT

Vascular


21/36

21

Small Intestine

Absorbs

80% ingested water

Electrolytes

Vitamins

Minerals

Carbonates

Active/facilitatedtransport

Monosaccharides

Proteins Di-/tripeptides

Amino acids

Lipids

Monoglycerides

Fatty acids

Micelles Chylomicrons


22/36

22

Structure of the Villi in the

Small Intestine


23/36

23

Small Intestine

Secretes digestiveenzymes Peptidases

Amino-

Di- Tri-

Sucrases

Maltase

Lactase

Saccharidases Di-

Tri-

Lipase

Nucleases


24/36

24

Small Intestine

Requires pancreatic

enzymes & bile to

complete digestion


25/36

25

Large Intestine

Extends from ileocecal valve to anus

Regions

CecumAppendix

Colon

Ascending

Transverse

Descending

Rectum

Anal canal


26/36

26

Anatomy of the Large Intestine


27/36

27

Large Intestine

Histology

No villi

No permanent circular foldsSmooth muscle

Taeniae coli

Haustra

Epiploic appendages

Otherwise like rest of Gl tract


28/36

28

Large Intestine

Functions

Mechanical digestion

Haustral churning

Peristalsis

Reflexes

Gastroileal

Gastrocolic

Chemical digestion

Bacterial digestion Ferment carbohydrates

Protein/amino acid

breakdown

Absorbs

More water

Vitamins

B

K

Concentrate/eliminatewastes


29/36

29

Feces Formation and Defecation

Chyme dehydrated toform feces

Feces composition

Water

Inorganic salts

Epithelial cells

Bacteria

Byproducts of digestion

Defecation Peristalsis pushes feces

into rectum

Rectal walls stretch

Control

Parasympathetic

Voluntary


30/36

30

Liver

Location

R. Hypochondrium

Epigastric region

4 Lobes Left

Quadrate

Caudate

Right

Each lobe has lobulesContains hepatocytesSurround sinusoidsFeed into central vein


31/36

31

Liver

Functions

Makes bile

Detergentemulsifiesfats

Release promoted by: Vagus n.

Secretin

Contains

Water

Bile salts

Bile pigments Electrolytes

Cholesterol

Lecithin


32/36

32

Liver

Detoxifies/removes

Drugs

Alcohol

Stores

Gycolgen

Vitamins (A, D, E, K)

Fe and other minerals

Cholesterol

Activates vitamin D

Fetal RBC production

Phagocytosis

Metabolizes absorbed foodmolecules

Carbohydrates

Proteins

Lipids


33/36

33

Liver

Dual blood supply

Hepatic portal vein

Direct input from small

intestine Hepatic artery/vein

Direct links to heart


34/36

34

The Duodenum and Related

Organs


35/36

35

The Organs and Positions in the

Abdominal Cavity


36/36

36

Structures of the Alimentary

Canal

digestivesystem 2012

Documents