THE DIGESTIVE SYSTEM Presented By Sam Lund Donovan

THE DIGESTIVE SYSTEM Presented By: Sam Lund, Donovan Parker, Tom Srebernak

Goals of the Digestive System 1. Extract nutrients from food 2. Transform nutrients into useful forms Ex. Oreo= Glucose (sugar) 3. Absorb nutrients and distribute them where they are needed

Functions of the Digestive System Ingestion: Intake of nutrients Digestion: Breakdown of large particles into smaller ones Absorption: Uptake of nutrient molecules Defecation: Elimination of undigested residues

Actions of the Digestive System 1. Intake - Breaks up food Moves food through the GI tract (Peristalsis) Mixes with digestive enzymes 2. Secretion - Release of enzymes and hormones for chemical digestion and regulation 3. Membrane Transport - Absorption of nutrients from the tissues by the blood and lymph for transport

Stages of Digestion Mechanical: Physical breakdown of food Chemical: Digestive enzymes hydrolyze food particles to break larger molecules into smaller ones Some nutrients are absorbed without digestion Vitamins, minerals, cholesterol, water

Anatomy of the Digestive System Oral Cavity Pharynx Esophagus Stomach Small Intestine Large Intestine

Small Intestine 6 meters in length Functions: Chemical Digestion Nutrient Absorption Nutrient Transportation

Functions of the Small Intestine Digestion and absorption of food Digestive enzymes secreted by the pancreas Enter the small intestine via the pancreatic duct.

Anatomy of the Small Intestine Duodenum (25 cm) Food mixes with bile from the gallbladder. Jejunum (2. 5 m) Absorbs nutrients into the bloodstream. Ileum (3. 6 m) Reabsorbs bile acids.

Large Intestine 1. 5 meters long Responsible for absorption of water from the indigestible residue of food

Anatomy of the Large Intestine Ascending Colon: Up the right side Cecum: Sac on lower right side Descending Colon: Down the left side Sigmoid Colon: S-shaped

Anatomy of the Large Intestine Ascending Colon-Removes water and other nutrients Transverse Colon-Expulsion of waste materials, continues leaching out Descending Colon-Absorbs water from fecal matter. Stores food particles that are to be emptied into the rectum. Sigmoid Colon- Make and eliminate feces. Contains 60 varieties of bacteria Rectum- Temporary storage for fecal matter before it’s eliminated from the body through the anal canal.

Oral Cavity Functions: A. Ingestion: Cheeks lips and tongue mobilize food B. Digestion: Mechanical Mastication Chemical 3 salivary glands Digests some starches and fat

Pharynx Purpose: Pharyngeal constrictors force food down during swallowing Divided into 3 parts: Epipharynx Mesopharynx Hypopharynx

Esophagus Straight Muscular tube about 1 foot long Purpose: Muscular contraction moves food towards stomach

Stomach Muscular sac on the left side of the peritoneal cavity Functions: Food storage Mechanical digestion Chemical digestion

Enzymes Involved in Chemical Digestion Saliva: Amylase: Breaks down starch Lipase: Breaks down fats when it enters the stomach Stomach: HCL: Activates enzymes, breaks up foods Pepsin: Digests proteins Renin: Digests milk

Final Destinations of Digestion Products Starches bloodstream Fats lymph vessels (lacteals) Proteins bloodstream