BIOL 1410 L15: The Digestive System

What forms the digestive tract? (2)

1. Gastrointestinal tract

2. Accessory organs

What is the gastrointestinal tract?

A tube that stretches form the mouth to the anus

Accessory organs (6)

• Teeth

• Tongue

• Salivary glands

• Pancreas

• Liver

• Gall bladder

Digestive tract functions in (4)

1. Ingestion

2. Digestion

3. Absorption

4. Defacation

Digestion

The break down of large molecules into smaller molecules

What types of digestion are there? (2)

1. Mechanical

2. Chemical

Mechanical digestion

Chewing, churning of food, segmentation of food, peristalsis (propels food along the length of the gI tract)

Chemical digestion

Enzymes and acid secretion function to break food

Absorption

End products of digestion are taken up into the blood and the lymph

Defecation

Elimination of wastes and undigested materials

What is visceral smooth muscle composed of?

Thick and thin myofilaments

Does smooth muscle have the same striations as cardiac and skeletal muscle?

No - has no myofibrils or sarcomeres

Smooth muscle cells characteristics (3)

• Spindle-shaped

• Contain one centrally located nucleus

• Gap junctions

Why are smooth muscle cells connected by gap junctions?

Allows for simultaneous muscle contractions (message communicated to cells at the same time)

Syncytium

Unit of muscles arranged as sheets - smooth muscle