III. Cell Death: Radiant Energy

Types of Radiation that Can Cause Cell Damage: Sunlight (ultraviolet) X-rays Radioactive products

These forms of radiation can put a charge on different “molecular parts” of the cell and cause damage or death

Two theories that focus on Cell Damage Resulting from Radiation: If the “stuff” inside a cell becomes charged, the cell becomes unstable May become charged by adding or removing electrons Also called ionization of cellular constituents If the water within a cell become charged, the cell becomes unstable

They create free radicals All forms of radiation put a charge on molecules that should not be charged They create free radicals Free radicals are very unstable and attempt to bond to other compounds in the cell thus creating more free radicals https://www.youtube.com/watch?v=KCF6prDSrHE

Two types of Radiation: Particles (alpha and beta) Waves (gamma and x-ray)

Characteristics of Radiation Relative to Tissue: (Skin Cells) Alpha particles: Slow speed, little penetration, great amount of damage Beta particles: Faster speed, greater penetration, less damage per cell X-ray waves: Even faster speed, greater penetration, little cell damage Gamma waves: Very fast, goes through most materials, causes very little damage

They are inversely proportional What is the relationship between speed of particles/waves and damage to tissue? They are inversely proportional The slower the speed, the greater the damage per cell

Radiosensitivity of Different Tissue: A normal chest x-ray gives off approximately 20 millirads Not considered harmful if done infrequently

Lymphoid tissue (spleen, lymph nodes, etc) RADIOSENSITIVE: Exposure to 2,500 rads or less causes serious cell damage or death to the following: Lymphoid tissue (spleen, lymph nodes, etc) Blood forming organs (bone marrow) Lining tissue of gastrointestinal tract Testes Ovaries Embryo/fetus—especially early in pregnancy Cancer

What is it that the above assorted tissues have in common such that they are all radiosensitive? All are undergoing mitosis What if a mistake occurs here?

Growing bone and cartilage RADIORESPONSIVE: Exposure to 2500--5000 rads or less causes serious cell damage or death to the following: Skin UVA light Blood vessels Growing bone and cartilage Conjunctiva, lens, and cornea (structures of the eye)

RADIORESISTANT: more than 5000 rads may cause cell damage or death Can take a large dose of radiation Pituitary Master gland of endocrine system

Adrenal glands located on top of the kidneys

Parathyroid Maintains calcium levels functions in bone density

Mature bone and cartilage Liver Striated muscle Ex. Biceps Brain Thyroid Pancreas Kidneys Mature bone and cartilage

Radiation can cause cancer cells, but can also treat cancer without damaging surrounding cells