Respiratory and digestion lab Flashcards
Lumen
A cavity or hole inside of a tube, blood vessel or hollow organ. For example, the blood flows through the lumen 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. Ducts are comprised of simple cuboidal epithelium, arranged in a doughnut pattern.
Lobes
Large, roundish projections or divisions of an organ. Lobes 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.
4 layers of the alimentary canal
- Serosa- outer
- Muscularis externa
- Submucosa
- Mucosa- inner
Serosa
A very thin tunic made of simple squamous epithelium that surrounds the outside of the organ. It is often difficult to see because it is so thin, but it is always present in these organs
Muscularis externa
Comprised of at least two layers of the smooth muscle - the outer layer always has muscle fibers running longitudinally down the organ and the next layer in has muscle fibers running circularly around the organ. The muscle layers help in peristalsis; the wavelike movement of muscles moving foodstuffs through the alimentary canal to the outside of the body. The easiest way to distinguish the two layers of the muscularis externa is to look for a subtle change in direction of the muscle cell nuclei. In one layer, the nuclei should look like cigars; in the other they should look round
Submucosa
Empty looking tunic in most organs, containing only scattered nuclei, a few wavy collagen fibers and sometimes glandular tissue.
Mucosa
Closest to the lumen, composed of 3 sublayers
3 layers of the mucosa
- Muscularis mucosa- outer
- Lamina propria
- Epithelium- inner
Muscularis mucosa
A very thin layer of smooth muscle, usually quite distinct as a dark pink band
Lamina propria
A loose matrix of cells and ground tissue
Epithelium
Protects the organ from the contents in the lumen.
