Lab 6: Respiratory/Digestive System Description

Lumen

A cavity or hole inside of a tube, blood vessel or hollow organ

• Ex: The blood flows through this of a blood vessel

Acini

A small, ball-shaped cluster of secretory cells surrounding Ducts

Duct

A tubular structure that transports secretions of a gland

• Are comprised of simple cuboidal epithelium, arranged in a doughnut pattern

Lobes

Large, roundish projections or divisions of an organ

• Can be seen with the naked eye

Lobules

Small divisions of the cells in an organ, forming a functional unit, lobules usually require a microscope to be seen

Serosa

A very thin tunic made of simple squamous epithelium that surrounds the outside of the organ

• Often difficult to see because it is so thin, but it is always present in these organs

Muscularis Externa

Lies immediately inside the serosa, it is compromised of at least two layers of smooth muscle

• Muscle layer help in peristalsis (wavelike movement)

• In one layer; the nuclei should look like cigars, other layer: look round

Submucosa

Lay next to muscularis externa, rather empty looking tunic in most organs

• Containing scattered nuclei, a few wavy collagen fibers and sometimes glandular tissue

Mucosa

Closest to the lumen, comprised of three sublayers

• Muscularis Mucosa

  • It is a very thin layer of smooth muscle, usually quite distinct as a dark pink band

• Lamina Propria

  • Loose matrix of cells and ground tissue

• Epithelium

  • Protects the organs from the content in the lumen

Layers of the Alimentary Canal in Order

Serosa → Muscularis Externa → Submucousa → Mucous

Mediastinum

Central, connective tissue filled compartment of the thoracic cavity, houses the heart

Visceral Peritoneum

The inner layer of the serous membrane that directly covers and wraps around internal abdominal organs

Parietal Peritoneum

The outer layer of the serous membrane lining the internal surface of the abdominopelvic wall, providing support and protection

Visceral Pleura

A thin, serous membrane that directly covers the inner surface of the lungs

Parietal Pleura

The outer serous membrane that lines the inner surface of the thoracic cavity