Tuesday, September 29, 2009

A Microscopic View of Life

Here is a glimpse from my biology class. There are four main types of tissue in the body: nervous, muscular, epithelial, and connective tissues. Each tissue is specifically adapted to fill specialized roles and functions within our bodies. The following are some of the microscope slides we looked at. I find the complexity and specialization to be intriguing, beautiful, and miraculous.

Nervous tissue: The cell body of a neuron and its cell processes (axons, dendrites), responsible for transmitting electrical impulses throughout our bodies.

Muscular tissue, specifically skeletal muscle: Highly striated (striped) cells called muscle fibers (lower half of the slide), which are responsible for our voluntary movements. These cells are specialized to contract in response to various types of stimuli.

Muscular tissue, specifically cardiac muscle: This slide is specially stained to see the tiny vertical lines called intercalated discs, which are responsible for cell-to-cell communication in the heart. Note the faint striations in cardiocytes (cardiac cells) as compared to the skeletal muscle slide.

Epithelial tissue, specifically stratified squamous epithelium: Many layers of flat cells comprise the inner lining of the esophagus. Why? The food swallowed is quite abrasive and wears away at the epithelium. By having many layers of cells, there are always new cells developing in the deeper layers to replace the cells being worn away at the surface next to the food. In general, epithelial tissue covers body surfaces, lines body cavities, covers surfaces of organs and glands, and more.

Epithelial tissue, specifically pseudostratified columnar epithelium with cilia: The cilia move mucus up out of the trachea. The mucus captures inhaled particles. In this way, particles from the air don’t travel to the deeper areas of the respiratory tract.