Biology: Digestion

Trace the movement of food through the human digestive tract.

Food enters the oral cavity and proceeds past the epiglottis down the esophagus to the stomach. After being liquefied in the stomach, the food travels through the small intestine then the large intestine. Parts of the food that remain undigested are eliminated through the anus as feces.

What is the role of gastrin in digestion?

Gastrin is a hormone secreted by the stomach that induces glands to produce hydrochloric acid for digestion.

How does acid affect pepsinogen?

Hydrochloric acid changes inactive pepsinogen into active pepsin.

MOUTH (ORAL CAVITY)

INGESTION OF FOOD PHYSICAL DIGESTION BEGINNING OF CARBOHYDRATE DIGESTION (SALIVARY AMYLASE FROM THE SALIVARY GLANDS)

SMALL INTESTINE

NUTRIENT ABSORPTION OF DIGESTIVE END PRODUCTS (MONOMERS) INTO THE BLOOD THROUGH STRUCTURES CALLED VILLI BASIC ENVIRONMENT (pH 8) HORMONE PRODUCED IS SECRETIN (WHICH STIMULATES THE PANCREAS TO SECRETE PANCREATIC JUICE)

LIVER (SECRETORY ORGAN)

PRODUCES AND RELEASES BILE TO EMULSIFY (BREAKDOWN FROM LARGE TO SMALL) LIPIDS

ESOPHAGUS

TUBE OFF THE PHARYNX THAT CONTRACTS (CALLED PERISTALSIS) TO PUSH FOOD TO STOMACH

Pepsin

The active protein-digesting enzyme in the stomach, which is secreted by stomach gland cells in an inactive form called pepsinogen

LARGE INTESTINE

WATER ABSORPTION WASTE FOR EGESTION (REMOVAL) FROM THE BODY

chemical

breaking down of complex molecules into smaller (carbs, lipids, proteins)

2 types

intracellular and extracellular

digestion

process that breaks down food

intracellular and examples

within the cell examples: plants; paramecium (protists) *enzymes break down food into small molecules the cell can use*

complete digestive system and examples

example: earthworm *two openings (mouth and anus)*

incomplete digestive system and examples

example: starfish *one opening (mouth or oral cavity)*

Bile

A substance secreted by the liver and stores in the gallbladder

PANCREAS (SECRETORY ORGAN)

PRODUCES PANCREATIC JUICE TO MAKE THE SMALL INTESTINE BASIC (pH NEAR 8) RELEASES THE ENZYMES PANCREATIC AMYLASE (CARBS), TRYPSIN (PROTEINS), LIPASE (LIPIDS) INTO THE SMALL INTESTINE

GALL BLADDER

STORES BILE AND RELEASES IT INTO THE SMALL INTESTINE THROUGH THE BILE DUCT GALLSTONES CAN FORM HERE

Saliva

A watery secretion containing dishes give enzymes that begin chemical digestion

Gastrin

As food enters the stomach, it stimulates certain cells to release this hormone which enters the bloodstream

STOMACH

BREAKS DOWN FOOD INTO A PASTE-LIKE CONSISTENCY CONTAINS HYDROCHLORIC ACID (pH NEAR 2) HORMONE GASTRIN IS PRODUCED TO STIMULATE ACID PRODUCTION SECRETES PEPSIN (ACTIVE FORM OF PEPSINOGEN) TO BEGIN PROTEIN DIGESTION MUCUS LINING FOR PROTECTION SORES CALLED ULCERS CAN FORM

Lipase

A far digesting enzyme which is secreted in the pancreatic and intestinal juices, splits fats into fatty acids and glycerol

Explain the digestion of carbohydrates. Be sure to include the regions of the digestive tract where carbohydrate digestion occurs.

Digestion of carbohydrates begins in the mouth. The enzyme amylase contained in the saliva breaks down bonds in starch molecules and adds water to the food. No further carbohydrate digestion occurs in the stomach due to its acid pH. Completion of digestion takes place in the small intestine, resulting in the formation of glucose.

Explain how digestive systems in different multicellular animals are adaptive.

Digestive systems in multicellular animals are adapted to the animal's diet. For example, stomach of cows, horses and rabbits have side pockets that contain microorganisms that aid in the digestion of cellulose in their diets. Since meat is easier to digest, the digestive tracts of carnivores are relatively short.

EPIGLOTTIS

FLAP TO COVER TRACHEA OR AIRWAY

Trypsin

It's an intestinal enzyme that breaks peptide bonds, producing amino acids from polypeptides

Peristalsis

Wavelike contractions of the muscles of the esophagus move food to the stomach in this process

Salivary amylase

Carbohydrate digestion begins in the mouths itch the action of this enzyme

What is the role of the small intestine in the digestion of proteins and fats?

When proteins enter the small intestine, they are acted on by pancreatic juice that raises the pH so that enzymes such as trypsin can break peptide bonds to produce amino acids from polypeptides. When fats enter the small intestine, they are mixed with bile that breaks down fat droplets into small particles that can be further broken down by enzymes such as lipase.

2 types of animal systems

incomplete and complete digestive system

physical

large pieces are broken into smaller ones also known as mechanical *both earthworms and birds use a gizzard to grind up food using sand and stones*

extracellular and examples

outside the cell example: animals *enzymes are secreted into a digestive cavity where food is broken and the nutrients are passed to cells*

2 parts to digestion

physical and chemical

Ingestion

The process of taking food into the digestive tract and it begins in the oral cavity

Villi

The surface area of the intestinal lining is increased tremendously by millions of small finger like projections

Capillaries

Tiny, thin walled blood vessels that serve as entry points to the bloodstream