Cells of the Human Body
Although there are specialized cells - both in structure and function - within the body, all cells have similarities in their structural organization and metabolic needs (such as maintaining energy levels via conversion of carbohydrate to ATP and using genes to create and maintain proteins).
Nerve Cells: Also called Neurons, these cells are in the nervous system and function to process and transmit information. They are the core components of the brain, spinal cord and peripheral nerves. They use chemical and electrical synapses to relay signals throughout the body. Epithelial cells: Functions of epithelial cells include secretion, absorption, protection, transcellular transport, sensation detection, and selective permeability. Epithelium lines both the outside (skin) and the inside cavities and lumen of bodies. Exocrine cells: These cells secrete products through ducts, such as mucus, sweat, or digestive enzymes. Endocrine cells: These cells are similar to exocrine cells, but secrete their products directly into the bloodstream instead of through a duct. Endocrine cells are found throughout the body but are concentrated in hormone-secreting glands such as the pituitary. Blood Cells: The most common types of blood cells are: 1. Red blood cells (erythrocytes). The main function of red blood cells is to collect oxygen in the lungs and deliver it through the blood to the body tissues. Gas exchange is carried out by simple diffusion . 2. Types of white blood cells (leukocytes). They are produced in the bone marrow and help the body to fight infectious disease and foreign objects in the immune system. White cells are found in the circulatory system, lymphatic system, spleen, and other body tissues.