Toxicology and its Division
“All substances are poisons. There is none which is not a poison. The right dose differentiates a poison & a remedy.”  - Paracelsus 1532
 
This quote explains that the probable for harm is prevalent and all substances could be toxic but the level of damage that a chemical can cause on a human depends on the dose or the degree of contact or exposure and on other factors. In other words the danger from a toxic substance depends on the contact or exposure.  

My blog is intended for those with slight or no background at all in toxicology. Toxicology is a difficult and complex science. It is the the study of adverse effects on humans of prophylactic & therapeutic drugs, food & beverage additives, and industrial chemicals incorporated into consumer products.


Terminologies used in Toxicity Screening:
 acute toxicity
§  administration of progressively larger single doses up to the lethal dose
§  “No-Effect” dose – largest dose at which a specific toxic effect is NOT seen
§  Minimum Lethal Dose – smallest amount of the drug that can kill a study animal
§  LD50 – dose that kills half of the experimental animal population
§  Toxic dose – dose that kills the patient.
§  Subtherapeutic dose – dose that has no effect.
§  Therapeutic dose – dose that cure the patient.
subacute / chronic toxicity
§  administration of multiple doses to detect any adverse effects
 
mutagenicity –
§  detection of possible ability to induce genetic alteration (mutation)

carcinogenicity –
§  detection of possible ability to induce abnormal clonal uncontrolled proliferation of genetically altered cells 
teratogenicity –
§  detection of possible deleterious effects on the developing fetus

“Local” refers to the site of action of an agent and means the action takes place at the point or area of contact.  The site may be skin, mucous membranes, the respiratory tract, gastrointestinal system, eyes, etc. Absorption does not necessarily occur.  Examples:  some strong acids or alkalis.  

“Systemic” refers to a site of action other than the point of contact and presupposes absorption has taken place.  For example, an inhaled material may act on the liver.  Example:  arsenic affects the blood, nervous system, liver, kidneys and skin.  

Cumulative poisons are characterized by materials that tend to build up in the body as a result of chronic exposure.  The effects are not seen until a critical body burden is reached. 
Example:  heavy metals (such as Lead).  

Synergistic responses:  When two or more hazardous material exposures occur, the resulting effect can be greater than the effect of the individual exposures.  Example:  exposure to both asbestos and tobacco smoke, producing lung cancer or mesothelioma.

To make it simple, here are some classification and examples of chemical hazards in the workplace and in the environment.

Category
Examples
Metals, and metalloids 
arsenic, cadmium, lead, mercury, nickel, tin, etc
Inorganics
asbestos, carbon monoxide, hydrogen sulphide
Hydrocarbons - aliphatic 
propane, butane, pentane, hexane
Aliphatic alcohols, ketones, ethers, aldehydes and acids
ethyl alcohol (ethanol), acetone, diethyl ether, formaldehyde, acetic acid
Hydrocarbons - aromatic 
benzene, toluene, xylene, naphthalene
Phenols 
phenol, pentachlorophenol
Chlorinated volatile organic compounds 
Perchlorethylene,(tetrachloroethene), trichloroethylene (trichloroethene), vinyl chloride
Chlorinated non volatile organic compounds 
chlorinated dioxins and dibenzofurans, polychlorinated biphenyls, pesticides such as chlordane and DDT
Miscellaneous organic compounds
acrylonitrile, benzidine, aniline, di-isocyanates, organophosphates


Hope my introduction gave you a lot of knowledge about the basic of Toxicology and it made you interested about the subject. Toxicology is a very exciting topic to talk about. Let’s now proceed to the divisions of Toxicology.

Divisions of Toxicology:

1. Drugs of abuse - drugs or chemicals which are taken repeatedly in a pattern & amount that interferes with one’s health or normal function. It have multiple effects, usually producing a feeling of well-being in the user and repeated use can lead to higher & higher dose needed to replicate the feeling causing emotional dependence, & in some, true physical dependence. Here are some examples:

a. Stimulants - drugs that "stimulate" or accelerate the central nervous system; usually  sympathomimetic Ex: Caffeine, Nicotine, Cocaine, Crack, Ecstasy, Amphetamines, Methamphetamines.

b. Hallucinogens - natural or synthetic drugs that can produce hallucinations when taken.  Ex:  LSD, PCP, DMT, DOM (STP), Psilocybin (“magic  mushrooms”), Peyote cactus, Mescaline, Marijuana, Ecstasy, and Ketamine. 

c. Cannabis - Cannabis is a collective term used to describe hemp plants that are smoked and ingested to produce psychophysical changes when ingested.  Ex: Marijuana, hash, and hash oil.  

d. Depressants - drugs which have a sedating effect upon the central nervous system.  

e. Opiates  & Opioids- narcotics that have a depressant effect upon the user.  Ex: Heroin, Meperidine  (Demerol), Morphine, Hydromorphone and Codeine.  

f. Sedative–Hypnotics - relaxants, induce sleep: Ex: Ethyl alcohol;    anti-anxiety agents-tranquilizers: benzodiazepines Diazepam, Rohypnol;     nonbarbiturates- Halcion, Quaalude;   long-acting barbiturates – Phenobarbital;    short-acting barbiturates – Seconal.  

g. Anabolic Steroids - Anabolic steroids are drugs or hormones akin to testosterone that increase muscle growth.  Ex: Halotestin, Maxibolin, Anavar, and Dianabol.

h. Volatile substances / Inhalants  - give off fumes for a high Ex: glue, aerosols, solvents.
i. Laxatives  - usually abused for weight loss  Ex:  Bisacodyl, Danthron, Phenolphthalen, Rhein.




 
Image Credit:  http://www.doctor-robert.com/wp-content/uploads/2012/06/drugs-alcohol-cigarettes.jpg
2. Emergency Toxicology - deals with emergencies such as poisonings, attempted suicides and overdoses.



Image Credit: http://www.globalpackagegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=64441&g2_serialNumber=2

3. Forensic Toxicology - Medico-legal aspects of poisonings. Establish relationship between tissue residual level and probable cause of death as well as identification and quantification of poisons.





Image Credit: http://ecx.images-amazon.com/images/I/51yWQjhy2ML._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01_.jpg

4. Industrial Toxicology - is a science that deals with potential harmful effects of materials, products and wastes on health and environments.





Image Credit: http://health.usf.edu/NR/rdonlyres/8F309F0B-7F97-42EC-9842-6D33CB7E6EB1/0/industrial.jpg

5. Therapeutic Drug Monitoring - is the measurement of specific drugs at timed intervals in order to maintain a relatively constant concentration of the medication in the bloodstream. Clinical application of Pharmacology; the rational use of drugs in the treatment of diseases.



Before I end my blog, here's a sample movie about forensic toxicology..
 
Thank you for spending your precious time in reading my blog. Hope I’d helped you a lot and motivated you to study about Toxicology.. ^^

References:
M. Bishop; Clinical Chemistry: Principles, Procedures, Correlations
D. Calbreath; Clinical Chemistry: A Fundamental Textbook

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Endocrinology (Endocrine System, Glands and Hormones)
What?! Endocrinology?! (?_?)\

What comes first in your mind when you hear the word “Endocrinology”? Definitely, you’ll say that Endocrinology is simply the study of the Endocrine system. But that’s right, it deals with the Endocrine system and also the secretions of its glands called hormones.

Maybe you’re wondering what chemistry had to do with you. Well, it do a lot! Your body secretes its own chemicals and uses them to control definite functions, and the main system that coordinates these chemicals is called the Endocrine system.

The fundamentals of the Endocrine system are the glands and hormones. The endocrine system is helpful in tissue function, regulating growth and development, metabolism and mood, as well as reproductive process and sexual function.

In general, the endocrine system is the one responsible for the different body processes that happen slowly inside our body, such as cell growth. While, faster processes like body movement and breathing are controlled by the nervous system. However, even if the nervous system and endocrine system are separate systems, they frequently act together to help the body function properly.

For the mean time, we’ll just talk about the basic terminologies of the Endocrine system, in order for us to understand the topic very well. And we won’t have a hard time in absorbing all the information about the topic. We’ll take it slowly but surely.. ;)

The endocrine system is composed of group of glands which secrete hormones. They are messengers formed by the body that transfer information from one cell or group of cells to another to coordinate the functions of different parts of the body. Hormones also control the way you respond to your environment, and they assist to give the appropriate quantity of energy and nutrition.

Now, let’s talk about the general parts of the Endrocrine system for us to know the different organs and glands that function together to maintain the body in good state.

The major glands that build up the human Endocrine system are the pituitary, hypothalamus, parathyroid, thyroid, pineal body, adrenal, and the reproductive glands, which comprise the testes and ovaries. Even the pancreas is also part of this system, even if it is also associated with the digestive system. Still the endocrine glands are the main hormone producers in the body, but some non-endocrine organs for example the heart, brain, liver, placenta, lungs, thymus, kidney and skin also release and produce hormones.

I prepare a summary of all the glands of the Endocrine system with the hormone/s it secreted and its primary action in order for us to appreciate it very well.. ;)

Endocrine Gland
Hormone/s Secreted
Primary Action
Hypothalamus
a.) The hypothalamus secretes two hormones: one that stimulates release and one that inhibits release.
b.) Oxytocin and Antidiuretic Hormone (Vasopressin)
a.) Control the function of the anterior pituitary gland



b.) Discharged from pituitary gland
Anterior portion of Pituitary Gland
a.) Corticotropin


 b.) Thyrotropin

c.) Follicle Stimulating Hormone



d.) Luteinizing Hormone




e.) Prolactin

f.) Growth Hormone
a.) Stimulates release of adrenal hormones involved in stress reactions
b.) Stimulates the discharge of thyroid hormones
c.) Kindles estrogen discharge and follicle development in females; promote spermatogenesis in males
d.) Stimulates corpus luteum formation and ovulation in females; promotes testosterone secretions in males
e.) Stimulates and sustain milk production
f.) Promotes  growth  in juveniles and is responsible in glucose and protein metabolism in adults
Posterior Pituitary Gland
a.) Oxytocin (manufactured in Hypothalamus)
b.) Antidiuretic Hormone (Vasopressin)
a.) Causes uterine contractions leading to birth
b.) Controls water balance in the body
Thyroid
a.) Triiodothyronine  and Tetraidothyronine or Thyroxine
b.) Calcitonin
a.) Regulates carbohydrates and lipid metabolism
b.) Lowers calcium levels in the body
Parathyroid
a.) Parathyroid Hormone
a.) Elevates calcium levels in the body
Cortex-Adrenal
a.) Glucocorticoids



b.) Mineralcorticoids

c.) Sex Hormones
a.) Assist  in controlling lipid and protein metabolism, Elevates blood sugar level
b.) Promotes sodium reabsorption in the kidney; salt and water balance
c.) Responsible for general growth and sexual maturity
Medulla-Adrenal
a.) Epinephrine



b.) Norepinephrine
a.) Raises force of heart contractions and rate, Elevates blood sugar level
b.) Supports dilation as well as constriction of blood vessels
Testes
a.) Testosterone
a.) Key role in spermatogenesis, development of genitals and secondary sex traits
Ovaries
a.) Progesterone



b.) Estrogen
a.) Prepares and maintains uterine lining, stimulates the breast development
b.) Key role in egg production, development of genitals and secondary sex traits
Pancreas
a.) Insulin
b.) Glucagon
a.) Lowers blood sugar level
b.) Raises blood sugar level
Thymus
a.) Thymosin
a.) Promote development of infection-fighting abilities and lymphocyte function in immune system
Pineal
a.) Melatonin
a.) Influences daily biorhythm, sexual activity and sexual development

Here’s the picture of the Human Endocrine System:
 

Image Credit: http://images.emedicinehealth.com/images/illustrations/endocrine_system.jpg

You can also watch this video to help you to understand the Human Endocrine System:
Video Credit: http://www.youtube.com/watch?v=D2MxmrOUl0w&feature=related
Thank you for your short time in reading my blog. I hope you learned a lot from my blog! Thanks!! God Bless!! ^_^\
References: Donald Calbreath; Clinical Chemistry: A Fundamental Textbook
                Michael Bishop; Clinical Chemistry: Techniques, Principles and Correlations 6th edition


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