Early Tissue Reactions and Their Effects on Organ Systems - BIO

Categories of damaging effects of radiation

Deterministic and stochastic

Deterministic effects

Tissue reactions, predictable (cataracts)

Stochastic effects

Random (cancer)

Somatic effects

Effects on the body when irradiated

Early effects

Biological effects of radiation occurring relatively soon after humans receive high doses of ionizing radiation

Early effects are

Not common with exceptions of length high dose procedures

Early tissue reactions have a

Threshold

Genetic effects

Effects upon future generations because of irradiation of germ cells in previous generations

The amount of biologic damage depends on the

Actual absorbed dose of ionizing radiation

High dose effects

Nausea and vomiting, fatigue, erythema, epilation, blood disorder, intestinal disorders, fever, sterility

Acute radiation syndrome

Radiation syndrome, occurs in human when whole body has received large doses delivered over a short period

Prodromal stage

24 hrs; severe nausea, vomiting, diarrhea

Latent stage

Symptoms disappeare

Whole body dose of 6 Gyt can result in

Many manifestations or organic damage occurring in succession

Manifest stage

Symptoms return, additional ones possible

Recovery or death stage

Last, Recover or die

ARS separate dose syndromes

Hematopoietic, gastrointestinal, cerebrovascular

Hematopoietic syndrome

Bone marrow syndrome, 1-10 Gyt, decrease BCs, survival shortens as dose increases

Hematopoietic syndrome death 2 Gyt

6-8 weeks

Hematopoietic syndrome death 2-10 Gyt

Die in shorter period

Hematopoietic syndrome death 1-2 Gyt

Bone marrow cells repopulate, recovery 3weeks to 6 months

ARS gastrointestinal 6 Gyt

Apparent threshold dose

ARS gastrointestinal issues peak after a dose of

10 Gyt

Doses typically resulting in death within 10 days

10 Gy or greater

A few hours after dose required what occurs

Prodromal stage (nausea, vomiting, diarrhea- up to 24 hours)

What occurs after Prodromal stage

Latent period

Most severely affected part of the GI tract during ARS GI syndrome

small intestine

In ARS GI syndrome Fatality occurs primarily because of

Catastrophic damage to the epithelial cells that line the GI tract

Without medical support to sustain life, exposed person of dose 6-10 Gyt may die in

3-10 days

ARE cerebrovascular syndrome results from

50 Gyt or more

ARS cerebrovascular syndrome causes damage to

CNS and cardiovascular system

ARS cerebrovascular syndrome outcome

Can cause death within a few hours to 2-3 days after exposure

Prodromal

1 Gy; nausea, vomiting, diarrhea, fatigue, leukopenia

Latent stage

1-100 Gy, no symptoms

Hematopoietic stage

1-10 Gy, 6-8 wk survival time (when dose over 2Gy), typical symptoms

GI stage

10-50 Gy, 3-10 day survival time, severe symptoms

Cerebrovascular stage

50+ Gy, several hours after dose-2/3 day survival time, typical symptoms plus neurological related symptoms

Chernobyl

Reactor explosion on April 26, 1896, 2 instant death, 29 deaths over 3 mo

Follow up studies of Hiroshima and Nagasaki survivors demonstrated

Late tissue reaction and stochastic effects of ionizing radiation

The atomic bombing of Hiroshima and Nagasaki created

Awareness of the need for a thorough understanding of ARS and appropriate medical support of persons affected

LD 50/30

Whole body dose of radiation that can be lethal to 50% of the exposed population within 30 days

LD 50/40 for adults

3-4 Gyt

Whole body doses greater than 8Gyt will cause

Death of the entire population in 30 days without medical support

LD 50/60

More accurate for humans

Repair and recovery can occur when cells are exposed to sublethal doses of ionizing radiation because

Cells contain a repair mechanism inherent to their biochemistry (repair enzyme)

The repair/recovery process permits an organ that has sustained functional damage as result of radiation exposure to

Gain some or most useful ability back

Have a better chance of recovery than hypoxic cells

Oxygenated cells

Have a cumulative effect

Repeated radiation injuries

Approximate percent of irreparable radiation induced damage

10

Local tissue damage

A destructive response in biologic tissue can occur when any part of the human body receives a high radiation dose

Significant cell death usually results after

Such a substantial partial body exposure

For local tissue damage, if recovery occurs it may be

Partial or complete, depends on type of cell and dose received

Law of bergonie and tribondeau

Cells are more radiosensitive if they are immature, rapidly dividing, and have high reproductive capacity

Organ and tissue response to radiation exposure depends on

Radiosensitivity, reproductive characteristics, growth rate

Local tissues suffering immediate consequences from high radiation doses

Skin, reproductive organs, bone marrow

Epidermis

Outer layer of skin

Dermis

Middle layer of skin

Hypodermis

Subcutaneous layer

Skin accessory structures

Hair follicles, sensory receptors, sebaceous glands, sweat glands

Desquamation

Generally manifests first as moist skin peeling, and then dry skin flaking may develop

Epilation or loss of hair (alopecia)

Moderate to high doses

Grenz rays

Historically used to treat and cure ringworm and other skin diseases

Modern radiation therapy treatment utilizes much high energy photons than

Orthovoltage rad therapy

Gonadal dose

Can depress sperm population or cause genetic mutation, may delt or suppress menstruation

Testes and ovaries do not respond the same to irradiation because of the

Differences in the method in which these cells are produced and progress from elementary stem cells to mature cells

Whole body dose as low as 0.25 Gyt would

Produce a measurable hematologic depression

Use of personnel dosimeters for monitoring of occupational exposure

Made the practice of requiring periodic blood counts for rad damage monitoring obsolete

Hematopoietic system consists of

Bone marrow, circulating organs, lymphoid organs (lymph nodes, spleen, thymus gland)

Hematopoietic system cells all develop from the precursor cell

Pluripotential stem cells

Lymphocyte

White blood cell

Neutrophil

White blood cell

Granulocyte

White blood cell

Thrombocyte

Platelets

Erythrocytes

red blood cell

Cytogenetics

Study of cell genetics with emphasis on cell chromosomes

Cytogenetic analysis of chromosomes completed using chromosome map called

Kart Karyotyoe

Cell phase where radiation damage to chromosomes is evaluated

Metaphase