Page 1 - Chapter 3: Cells and Tissues

Cells and Tissues
Cells and Tissues

LECTURE NOTES

I.- Cells

1) Overview

The cell is the structural and functional unit of all living matter.

Cells are made primarily of four elements: Carbon, hydrogen, oxygen and
nitrogen. Most of the cell is protein. There are other elements that are
called trace elements because they exist in small quantities. For example,
calcium is needed for blood coagulation, iron is necessary to make
hemoglobin; iodine is needed for the thyroid gland to manufacture the
thyroid hormone. In their ionic form, calcium, sodium and potassium can
carry an electrical charge. When they do they are called electrolytes.

Carbon C, Hydrogen H, oxygen O, nitrogen N, Iodine I, iron Fe,
calcium Ca, and potassium K.

Living cells are 60% water. H20

Cells vary dramatically in the functions, shape, and in the time they
live. Some of them are replaced every day while others are able to for
months or years.