A&P Unit 4 - Digestive System

Ingestion

taking food into the body (mouth)

Propulsion

moving food and nutrient along digestive tract

Mechanical digestion

the physical breakdown of food

Chemical digestion

breaks large food molecules into their chemical building blocks (polymer → monomer) 

Absorption

nutrients are absorbed by the bloodstream and transferred throughout the body 

Elimination 

getting rid of anything that has no nutritional value or cannot be absorbed through the anus 

Alimentary Canal

the path of food flow

Accessory Organs

food does not pass through, but they aid in digestion

Mouth, esophagus, stomach, small and large intestines

What organs are in the alimentary canal

Teeth, salivary glands, liver, gallbladder, pancreas 

What are the accessory organs 

Mucosa

the absorptive and secretory layer; composed of simple epithelial cells and connective tissue 

Submucosa

Has loose connective irregular tissue, glands, blood vessels, & nerves; its vessels nourish surrounding tissues & carry away absorbed materials 

Muscularis

Made of 2 layers of smooth muscle; the muscles cause food to move and churn w/ digestive enzymes down GI tract

Muscularis - Inner circular

constricts digestive tracts limen to mix food and prevent backward movement

Muscularis - Outer longitudinal

shortens the tract to propel food forward

Serosa

protective layer; secretes serous fluid that moisturizes and lubercates

Myenteric plexus 

responsible for motility contractions of the muscularis 

Submucoal plexus

responsible for regulation digestive secretions

Sphincters

a ring of muscle around opening of an organ; serves to contain substance in an organ

Glands

secrete many different chemicals and hormones along the GI

Mucosal barrier

forms a barrier and neutralizes acid

Mouth 

responsible for ingestion (taking in food)

Teeth

are the mechanical breakdown of food via mastication

Bolus

food missed with saliva

Incisors

Canines

Premolar

Molars

Tongue

Soft palate 

Hard palate

Uvula

Pharynx

the cavity lying behind the mouth that connects the mouth to the esophagus

Esophagus 

Stomach

Esophageal sphincter

Pyloric sphincter

Rugae 

Cardia

Fundus

Stomach body

Pyloris 

Gastric glands

Chief cells

secrete pepsinogen

Parietal cells

produce HCI

Mucous cells

produce alkaline mucous to coat the stomach

Small intestine

Duodenum

smallest and shortest part of the small intestine

Jejunum 

Ileum

Large intestine

Appendix

Ascending colon

Transverse colon

Descending colon

Sigmoid colon

Rectum 

Anus

Cecum

Pancreas

Liver

stores glycogen and vitamins A, D, B12; stabilizes fats, carbs and proteins

Gall bladder

stores and concentrates bile;

Enzymes

are catalysts in living things; needed for all processes in human body

Substances 

Reactants in an enzyme catalyzed reaction 

Active site

site to which the substrate binds

pH

measure the concentration of hydrogen ions in a solution

Low pH

is acidic

High pH

is basic