Physiological responses to toxicity summarizes the effects of environmental pollutants and toxicants on various physiological systems in aquatic organisms and other animals. Toxicants can disrupt sensory, hormonal, neurological, and metabolic systems, with implications for fish behavior. Commonly observed links between toxicant exposure and behavioral disruption include cholinesterase inhibition, altered neurotransmitter levels, and sensory deprivations. Toxicants can have systemic effects after absorption and distribution throughout the body or local effects at the contact site. Target organs most susceptible to toxic effects include the blood, liver, kidneys, skin, nervous system, and respiratory system. The physiological impacts range from minor irritation to organ damage and failure.

1. Physiological responses to toxicity
By Komal Gul

2. Physiological responses to toxicants
• Environmental pollutants such as metals, pesticides, and other organic poses
risks to many aquatic organisms.
• Accordingly a great deal of previous research has characterized physiological
mechanism of toxicity in animal exposed to contaminants.
• The affect of pollutant on the respiratory, cardiovascular ,osmoregulatory ,
neuro-endocrine process system are well described.
• Some of these responses (particularly ventilation, heart rate, and also body
ion fluxes) are bio-monitors or potentials biomarkers in the fields.

3. • Physiological effects of toxicants include disruption of sensory,
hormonal, neurological, and metabolic system which are likely to
have profounded implication for many fish behavior
• However, little toxicological research has sought to integrate the
behavioral effects of toxicants with physiological processes
• The most commonly observed links with behavioral disruption
include:
• Cholinesterase inhibition
• Altered brain neurotransmitters levels
• Sensory deprivations
• Impaired gonadal and thyroid hormone levels

4. • There are two main way in which chemical may exert their effect
• Systemic effect occur after the chemical has been observed and distributed
• Tetraethyl lead, which is gasoline addictive and produces skin effects at contact site.
• Local effect occur at area of the body which has been in contact with chemical
• Example, include external tissue injuries from acids or lung injuries from inhaled
receive gases

5. Target organ
• The degree of toxic effect is not the same in all organs
• Usually there are one or two organs which show the major toxic effect
• These are referred as target organ of toxicity of particularly substances.
• The blood circulation, liver, kidney, skin follow frequency of systemic effects.
• The central nervous system is the target organ of toxicity most frequently
involved in systemic effects.

6. Physiological effects of toxicants on human
& animal
• The body needs very small quantity of chemical that is poisonous
or large dose
• Adverse effect associated to dose
• The worse effect is fatality
• The effect may be reversible or irreversible
• May be immediate or delayed

7. SKIN
• The largest organ of the human body provides protective covers over to body
organ but can allow permeation of chemical if load is excessive
• Many substance can infiltrate through the skin and finds its way to
hematology
• Skin disorders may include eczemas, irritation and infection
• Common contact allergens include colorants dyes, nickel, cobalt, chromium
etc.

8. Kidney
• Kidney help excrete waste substances
that the blood transport s from various
organ of the body
• Solvent such as carbon tetrachloride
such may irritate and can severely
damage kidney function.
• Turpentine in large quantities is also
harmful to kidneys: painters kidney
known as condition related to

9. Nervous System
• Several types of substances acts as neurotoxins.
• The nervous system is sensitive to hazardous effect of organic
solvents, such as carbon disulfide.
• Some toxins that effect nervous system include lead, mercury and
manganese.
• Some organophosphate insecticides include malathion parathion
hinder chemical neuro transmitter function in nervous system
leading to paralysis, weakness and some time death.

10. Allergies
• Allergic reaction may appear after repetitive contact with the substance.
• Allergies can range from minor skin irritation to very severe or fatal reaction
• In human eyes allergies skin allergies are common.

11. Reproductive system
• Produce reproductive system defects
• Example include thalidomide, formamide, …etc.

12.  Blood
• The blood circulation system may also be
adversely affected by toxicants.
• For example benzene effect bone marrow:
the first sign is mutation in lymphocytes.
• Pure as well as compounds of lead ,carbon
monoxide, cyanides, may overcome
enzyme activities involved in the
production of hemoglobin in red blood cell
• Chronic lead poisoning, for example may
results in anemia

13. Lungs
• The lung is major route through which toxic substances in the workspace takes
enter in the body
• It is the first Organ affected by dust, solvent vapors, corrosive gases
• Allergies may be caused by substance such as cotton, dust, toluene.
• When dust particles size lower then 0.1micrometer are inhaled in lungs are unable
to exhale them
• They are embedded in lungs leading to cause pneumococcus
• Other substance such as aldehyde, formaldehyde sulfur and nitrogen oxides may
causes irritation and reduce breathing

14. Liver
• The main function of liver is breakdown
unwanted substances in blood.
• Solvents such as carbon tetrachloride,
chloroform, nitrosamine and vinyl chloride, as
well as alcohol are hazardous to the liver. Such
substance are termed hepato-toxins

15. Thank you so much for your kind attention