EXAM 1 Radiobiology Review

Ch 29, 30, 36

What is Covalent Bonding

characterized by the SHARING of electrons

“CO-Parenting”

What is Ionic Bonding

Occurs when two atoms are bound together by the attraction of their opposite charges

(Giving up electrons)

Deterministic Effect AKA

EARLY EFFECTS

What is Deterministic Effect?

biologic response whose severity varies with radiation dose

• A DOSE THRESHOLD USUALLY EXISTS - Minimum amount needed to cause a response

Stochastic Effect AKA

LATE EFFECT

What is Stochastic Effect?

Radiation response increases with increasing radiation dose

• There is NO threshold dose - ANY AMOUNT OF RADIATION CAN CAUSE A RESPONSE, THE MORE AMOUNT OF RADIATION THE GREATER THE RESPONSE

List deterministic effects

• GI Syndrome

• CNS Syndrome

• tissue damage to skin

• tissue damage to gonads

• cytogenic damage

List stochastic effects

• bone CA

• Lung CA

• Thyroid CA

• BREAST CA

• tissue damage to skin

• Tissue damage to eye

% Of how much water is the body made of?

80%

What are some of the duties of water in the molecular composition?

• needed to aid in digestion

• helps fight infections

• assists in removing toxins in body

• lubricates and cushions joints

• carries oxygen and nutrients to cells

• regulates body temp

• assists in metabolism working properly

• protects spinal cord and other important tissues

% of how much protein is the molecular composition?

15%

How is protein structured?

are long-chain macromolecules that consist of a linear sequence of amino acids attached by peptide bonds

how many amino acids are used in protein?

22 amino acids are used in protein synthesis

• protein synthesis metabolic production of proteins

amino acids = ?

Protein

What is Proteins role in the molecular composition?

• provides structure and support to all cells, organs, tissues and systems

• Gives energy

• helps grow / repair cells

• produces neurotransmitters to leep brain working properly

• maintains proper pH balance of body fluids

• aids immune system to function properly

How else can protein function?

Enzymes, hormones, and antibodies

Enzymes

molecules needed in small quantities to allow biochemical reactions

Hormones

molecules that are used for growth and development

Antibodies

primary defense mechanism against infections and disease

% of lipids in the molecular composition

2%

What are lipids?

are organic macromolecules made up of carbon, hydrogen, an oxygen

1 lipid molecule =

1 glycerol + 3 fatty acid

Where are lipids?

they are in all body tissue and are the structural portion of the cell membrane

Where are lipids located?

they are concentrated under the skin as a thermal insulator

What are lipids used for?

they serve as duel for energy storage for the body

What are carbs made of and its main function?

Made up of carbon, hydrogen and oxygen - their structure is different

What is the main function of carbs?

provide fuel for cell metabolism

What are other names for Carbs?

• Saccharides

• monosaccharides

• disaccharide

What does DNA do?

Controls cell function

What does DNA contain?

all genetic info necessary for cell replication

T/F DNA is radiation-sensitive ?

True

How is DNA structured?

Human DNA exists as a ladder

Side rails - sugar - phosphate molecules

Rungs - bases joined together by hydrogen bonds

Where is RNA located?

located mostly in cytoplam (but is also found in the nucleus)

What is RNA?

Molecules involved in the growth and development of a cell bu protein synthesis

main difference between organic and inorganic comopunds

organic compounds ALWAYS contain carbon, inorganic DOES NOT

Ex of Organic Compounds

1. DNA

2. TABLE SUGAR

3. BENZENE

4. METHANE

Ex of Inorganic

1. table salt or sodium chloride

2. carbon dioxide

3. diamond

Major Structure of human cell

1. nucleus

2. cytoplasm

Nucleus

A molecular strucure of DNA and some RNA, protein and water

Cystoplasm

Protoplasm that exists outside the cells nucleus

what happens to damaged cells by radiation?

cells may malfunction and die

Endoplasmic Reticulum

Channel or a series of channels that allows the nucleus to communicate with the cytoplasm

Mitochondria is known as?

Knon as the “engine of the cell”

Mitochondria is?

a large bean structure found within the cytoplasm of a cell that digest macromolecules for energy

Ribosomes

Small dot-like structure that is used for protein synthesis

Where are ribosomes scattered?

Scattered throughout both the cytoplasm and endoplasmic reticulum

Lysosomes

Small pea-like sacs that contain enzymes capable of digesting cellular fragment

Cell and its strucutre

All membranes consist of lipid-protein complexed that all small molecules and water to diffuse from one side to the other

What do experiments show regarding cells?

that the nucleus is much more sensitive than cytoplasm to the effects of radiation

Protein synthesis

metabolic production of proteins

• necessary for survival

Cell proliferation

act of a single or a group of cells that reproduce and multiply

Genetic Cells include?

Oogonium of the female and the spermatogonium of the male

meiosis

when genetic cells proliferation (divide)

Somatic Cells

all other cells in the body

mitosis

when somatic cells proliferate (divide)

Somatic Effects

occur in the exposed individual

Somatic Short term effect

usually occur soon after an acute dose (10rads or greater within a few months of exposure)

ex: temp hair loss

Somatic Late term effect

occurs years after the exposure that caused it

ex: cancer and cataracts

Mitosis

process of somatic cell division where a parent cell divides to form two daughter cells that are identical to the parent cell

What are the subcategories of Mitosis

A. Prophase

B. Metaphase

C. Anaphase

D. Telophase

Pass My Anatomy Test

What is interphase?

is the period of growth of cells between division

What does each phase include?

Each cycle includes various states of cell growth, development, and division

Prophase -

nucleus and chromosomes enlarge and DNA take structural form

ENALRGE

Metaphase -

Chromosomes move and align themselves at the center of the cell

MOVE

Anaphase -

The sister chromatids of each chromosome divide and move toward opposite poles due to the shortening of the spindle fibers

DIVIDE

Telophase -

The Chromatids (now called chromosomes) are located on opposite poles. Nuclear membrane forms around the chromosomes which start to uncoil. The spindle fibers dissolve and disappear

Meiosis

Process if germ cell division that reduces that chromosomes in each daughter cell to half the number of chromosomes in the parent cell

What is the end result of Meiosis?

end result is 4 cells are created from the original 1 cell

Tissue

Collection of cells of similar structure and function

Organ

Collection of tissue of similar structure and function

Organ Systems in the body

nervous

digestive

endocrine

respiratory

reproductive

What is the LAW OF BERGONIE AND TRIBONDEAU

The radiosensitivity of tissue depends on the number of undifferentiated cells which the tissue contains, the degree of mitotic activity in the tissue and the length of time that cells of the tissue stay in active proliferation (duplication of cell)

What is LET

Linear Energy Transfer

LET is?

measure of rate at which energy is transferred from ionizing radiation to tissue

LET is expressed

in kiloelectron volts of energy trnasferred per micrometer (keV/um)

What is relative biologic effectivemness

ratio of the dose of standard radiation necessary to produce a given effect / dose of test radiation needed for the same effect

As LET radiation increases = ?

the ability to produce biologic damage also increase

Protraction

dose delivered continuously but lower dose rate

Fractionation

dose delivered at a high rate but divided into smaller doses (radiation therapy)

Oxygen Effect

tissue is more sensitive to radiation when irradiated in an oxygenated state

Oxygen Enhancement Ratio

Dose necessary under anoxic conditions to produce a given effect/dose necessary under aerobic conditions to produce the same effect

Diag x-ray are performed under what conditions?

of fully oxygenation

Radiation Dose - Response relationship

A graphic representation of the relationship between the amount of radiation absorbed by a cell (dose) and the amount of damage (response)

Linear dose response

response directly related to dose

• higher the dose = higher the response

non-linear dose response

response varied with different doses

• doubling the dose, does not double the response

Threshold

needs to meet a certain amount of dose in order to receive a response, other wise there is no response

non-threshold

any dose can produce a response

Deterministic Effect

Response usually follows high-dose exposure and an early response

• threshold

• Ex: radiation induced skin burn

Stocastic Effect

Low radiation exposure and appear as a late radiation response

• Ex: CA, Leukemia, or genetic effects

Linear Dose Response

1 dose and increasing as dose increases

non Linear

varying dose

Leakage Radiation is emitted how?

from tube housing isotropically (emitted evenly from all directions)

Leakage Radiation should not exceed?

100 mR/hr at 1 meter

Scatter is produced primarily from ?

Compton interaction

What factors increase scatter?

1. high kVp

2. Large field Size

3. Thick body part