Digestive System

Path of food through the digestive tract 

Mouth 

Mechanical: teeth, tongue, muscles, saliva 

Chemical: amylase and lipase in saliva 

Pharynx: pathway 

Esophagus: pathway 

Stomach: protein digestion (3 cell types are mucus, parietal, and chief) 

Duodenum: chemical digestion and start of absorption 

Jejunum and ileum: absorption 

Cecum: beginning of large intestine and collects waste 

Colon: absorbs electrolytes, vitamins, water, and FAs 

Rectum  

Anus 

Sites of mechanical digestion 

Sites of chemical digestion 

Enzymes involved in chemical digestion 

Amylase, lipase, protease, and nuclease 

Structures of the oral cavity and their roles 

Function and structure of the hard palate 

Separates respiratory and digestive tracts to permit breathing while eating 

Functions of the soft palate 

Separates digestive and respiratory tracts during swallowing 

Aids in suckling in infants 

Types of teeth and their roles 

32 total teeth 

Incisors: 8, chisel-like, grasp, pull, break off food 

Canines: 4, cuspids, puncture, tear, and shred food 

Pre-molars: 8, bicuspids, grind and crush food 

Molars: 12, tricuspids, grind and crush food 

Steps/processes of the swallow reflex 

Swallow, soft palate flips up and blocks access to nose, epiglottis closes over larynx so food doesn’t enter trachea, esophagus relaxes to let food in, esophagus peristalsis down to esophageal sphincter, food enters stomach 

Structure of the esophagus and function 

Structure: non-keratinized stratified squamous epithelium (similar to skin)(for protection) 

Layers of alimentary canal and tissues 

Mucosa, submucosa, muscular, adventita 

Functions of blood vessels & lymph lacteals 

Nutrient absorption and removal 

How peristalsis works 

Longitudinal muscles shorten the tube 

Circular muscles constrict the tube 

Regions and function of the stomach 

Cardia: contains mucus glands to lubricate and protect, produces the gastric juices? 

Fundus: Serves as storage area and responsible for chemical digestion 

Body: Where food is mixed and partially digested 

Mucus glands produce a bicarbonate-rich mucus to protect lining 

Parietal cells produce HCl to denature proteins 

Chief cells produce pepsinogen which becomes an active enzyme (pepsin) when it comes in contact with HCl  

Chyme is formed here 

Pylorus: Accepts chyme, pyloric glands release neutralizing mucus, passes chyme to small intestine 

Gastric pit cell types and roles 

Role of the pylorus and pyloric gland 

Pylorus: Accepts chyme, pyloric glands release neutralizing mucus, passes chyme to small intestine 

Functions of the small intestine 

Chemical digestions, nutrient/water absorption, waste removal, bacterial barrier 

Villi and microvilli and their roles 

Roles: maximize surface area, digestion, and absorption of nutrients 

Cells possess microvilli to maximize surface area 

Digestive enzymes are bound to the microvilli 

Permits efficient digestion and nutrient absorption 

Submucosa contains blood vessels and lymphatic lacteals 

Rapidly shuttle nutrients away to keep absorption favorable 

Duodenum vs. Jejunum/ileum 

Duodenum digests/breaks up food chemically 

Jejunum/ileum absorb the digested nutrients 

Function of pancreas and what is made there 

Forms from buds of the liver and intestines 

Produces lipases, nucleases, amylases, and proteases. Also releases bicarbonate ions to neutralize chyme (in duodenum) 

Secretions enter duodenum via pancreatic duct 

What is bile and what does it do? 

Emulsifies (breaks down into small droplets) fats/lipids 

Bile contains pigments, electrolytes, cholesterol, phospholipids, and salts 

Role of the gallbladder 

Store bile 

Functions of the liver 

Processes all nutrients 

Blood from intestines enters via hepatic portal vein, passing through hepatic sinusoids to a central vein 

Role of the cecum 

Collects waste left over after all the nutrients are absorbed 

Collecting area from ileum that connects to a blind ended appendix and the beginning of the colon/large intestine 

Role of the appendix 

Houses bacteria? 

What happens in the large intestine? 

Lacks villi and digestive enzymes, supports bacterial colonies 

Re-absorbs water, vitamins, FAs, and mucus (to protect lining) 

Roles of each nutrient type 

Carbs – energy 

Lipids – structure and communication 

Proteins – building blocks 

Nucleic Acids - info 

What are essential nutrients? 

Saturated vs. unsaturated fatty acids 

Combine with phosphates to make phospholipid bilayers or combine with proteins to form lipoproteins 

Roles of LDL and HDL and human health 

LDL: hold lots of cholesterol, carries fat and cholesterol to tissues for storage 

HDL: mostly proteins, picks up excess fat and cholesterol (from tissues) and removes it 

Complete vs. incomplete proteins 

Most animal proteins are complete proteins 

Plants are incomplete proteins (don’t contain all AAs) 

What is a vitamin? 

Necessary organics 

What are minerals? 

Necessary inorganics