RAD BIO CH.8

Early Effects of Radiation Exposure

produced by a substantial dose of ionizing radiation that can lead to biological effects soon after humans are exposed

Somatic effects

"soma" meaning "body", therefore are effects upon the body that was irradiated.

True/False: Somatic effects can be classified as either early or late radiation syndrome reactions

True. There are early (acute/non-stochastic) effects and late (delayed/stochastic) effects

Genetic Effects

Effects of radiation that are passed on to future generations through genetic cells

As radiation dose increases, the severity of early tissue reactions:

also increases

True/False: the amount of biological damage does not depend on the actual absorbed dose of ionizing radiation

False

if the consequences include the killing the cell and are directly related to the dose received, they are

early somatic tissue reactions

Early tissue reactions

have a threshold, a point at which they begin to appear and below which they are absent

Early tissue reactions can appear within

minutes, hours, days, or weeks of the time of radiation exposure

Effects of high dose radiation in early tissue reactions include

~nausea

Fever

Fatigue

erythema

epilation

Intestinal disorders

Blood disorders

~ injury to CNS at extremely high radiation doses

temporary or permanent sterility in both male and females

depressed sperm count in males

dry and moist desquamation

whole body doses of ____ can result in acute radiation syndrome

6Gy(t)

Acute radiation Syndrome (ARS)

Termed radiation sickness. Occurs in humans after whole-body reception of large doses of ionizing radiation over a short-term period (ex. Hiroshima)

ARS four main stages

~prodromal stage: first stage occurs within hrs of exposure of 1gy(t) with symptoms such as NVD

latent stage: after prodromal stage within 1 week presenting with no visible symptoms

manifest illness: occurs after latent stage

recovery or death: if cell is able to recover after exposure it results in recovery

Symptoms of ARS

Hematopoietic syndrome

Gastrointestinal syndrome

Cerebrovascular syndrome

Hematopoietic (bone marrow syndrome)

~Occurs at 1 -10Gy received by the whole body

Due to blood cell production, it is a radiosensitive system causing short survival time as radiation exposure increases

Death to a person with hematopoietic syndrome that received a dose exceeding 2Gy(t)

may occur 6 to 8 weeks after exposure, NVD syndrome during the latent period

which blood cells are the most radiosensitive

white blood cells (leukocytes)

A decline in red blood cells (erythrocytes), white blood cells, and platelets lead to

weakening of the immune system and blood clotting abilities

Gastrointestinal (GI) syndrome

Appears at a threshold dose of approximately 6Gy(t) and peaks after 10Gy(t) resulting in death within 3-10 days even with medical prevention

stages of GI syndrome

~prodromal stage includes NVD

latent period of 3-5 days

manifest stage introduces a false calm before symptoms such as NVD, fever, fatigue, loss of appetite, anemia, lethargy, electrolyte imbalance, infection, emaciation, hemorrhage, and leukopenia occur

Cerebrovascular syndrome

occurs above a dose of 50Gy(t) resulting in immediate NVD and death within hours or 2 to 3 days following exposure

Stages of cerebrovascular syndrome

~prodromal stage includes NVD, confusion, severe nervousness, loss of vision and consciousness and burning sensation of skin

latent period of 6-12 hrs

~manifest stage includes SOB, ataxia, convulsions, fatigue, edema in cranial vault, disorientation, shock, lethargy, convulsive seizures, electrolyte imbalance, meningitis, prostration, vasculitis and coma

Lethal Dose (LD)

referred as LD 50/30 signifies the whole-body dose of radiation of 3.0 to 4.0 Gy(t) that can be lethal to 50% of the exposed within 30 days

approximately ___ of the radiation-induced damage will be irreparable, the remaining ___ may be replaced over time

10%;90%

local tissue damage

A destructive response in biologic tissue can occur when any part of the human body receives a high radiation dose leading to atrophy of organs or tissues

atrophy of organs or tissues

may loses ability to function or they may recover. If recovery occurs it may be partial or complete. Failure to recover results in necrosis or death of the irradiated object.

Skin

~epidermis (outer layer)

Dermis(middle layer)

hypodermis (subcutaneous layer)

Accessory structures of the skin

hair, sebaceous glands, sweat glands, sensory receptors

Radiodermitis

reddening of the skin caused by exposure to ionizing radiation

Desquamation

peeling/shedding of the outer layer of skin

Hair loss due to radiation

radiosensitivity of hair follicles results in temporary hair loss (moderate exposure) and permanent hair loss (large doses)

effects on the reproductive

gonadal doses (2 to 6Gy(t)) can vary and can affect genetic mutation to future generation, causes temporary or permanent sterility, and cause delay or suppression of menstruation

Cytogenetics

study of cell chromosomes accomplished through a karyotype (chromosome map)

High Radiosensitivity

bone marrow, spleen, thymus, lymphatic nodes, gonads, eye lens, lymphocytes

Medium radiosensitivity

skin, circulatory system (blood cells, vessels, and heart), connective tissues (bone, muscles, tendons, and dermal layer), kidney, excretory system, lymphatic system, reproductive system, digestive tract, skeletal muscles, red blood cells, tubules of the kidneys

Low Radiosensitivity

muscle, bones, nervous system