routes of exposure Flashcards
Exposure to toxic substances occurs through the three major routes
o The skin (dermal absorption)
o The respiratory tract (inhalation)
o The digestive tract (ingestion)
Contact with the skin is the most common path of toxic substance exposure
dermal absorption
The skin is composed of three layers:
- epidermis (outer layer)
- dermis (inner)
- subcutaneous fatty tissue
Factors affecting dermal absorption of toxic substances include
- the condition of the skin;
- chemical makeup of the substances;
- increasing concentration of toxic substance or exposure time
easiest and fastest means of exposure to toxic substances because toxic substances are readily absorbed in the respiratory tract.
inhalation
route of exposure that usually occurs accidentally or unknowingly
ingestion
other routes of exposure
eye and injections
common point of contact for toxic substances
eye and injections
primary point of contact for toxic substances
cornea
is affected because of the structure of the body and the length of time food containing the substance remains in the body.
absorption
After being taken up in the blood, a chemical is be quickly distributed throughout the body; it may be moved from one organ or tissue to another (____________) or changed into a new compound (_______)
translocation, biotransformation
outer layer of the eye is made up of connective tissue called
sclera
middle layer of the eye is called
choroid
Two compartments within the eye contain a fluid-like substance
aqueous humor
a transparent jelly-like substance
vitreous humor
are mainly used in laboratory studies on experimental animals.
injections
different types of injections
- Intravenous injections (into a vein).
- Intramuscular injections (into the muscle).
- Intra peritoneal injections (into the abdominal cavity)
- Intradermal injections (into the skin)
- Subcutaneous injections (under the skin).
occurs when a substance is changed from one form to another, which may also change the toxic properties of the substance.
biotransformation
. It usually occurs in several steps, primarily in the liver, but it may also occur in other tissue like the kidneys, lungs, and digestive tract.
biotransformation
The rate (speed) at which a toxic substance is removed from the body determines whether it will have a toxic effect on the body
excretion of toxins
The longer a chemical is in the body, the greater the likelihood of damage.
excretion of toxins
eliminates the greatest number of toxins than any other tissue/organ.
kidney
eliminate substances that are in the gaseous phase, like carbon dioxide.
lung
removes substances like lead or DDT (pesticide) by excreting them into bile, which is made by the liver and travels to the small intestine
liver
