Chemical ControlUnit 4.6

IntroductionThe endocrine system uses chemical

messages called hormones to transfer information around the body

Hormones are responsible for controlling many processes in your body, such as the storage and release of glucose into the blood.

Glands of the Endocrine SystemPituitary glandThyroid glandPancreasAdrenal glandOvariesTestes

Each having a set role to play in the regulation of bodily functions

HormonesAre chemicals produced by endocrine glands

which are located in many various parts of the body.

The endocrine glands work together as a system, yet they are not centrally controlled like the nervous system is.

Hormones regulate functions like growth, development, water balance, sexual reproduction and the rate of chemical reactions in the bodies cells.

How hormones workProduced and released by the gland into the

bodyTravel throughout the body.Certain cells respond to the hormone

[chemical], all others ‘block it’.When reaching the target cell they trigger a

certain activity or ‘task’ for the cell.The kidneys clean the hormones out of the

blood so they do not build up in the body.

Why hormones?The endocrine system works more slowly

than ‘instant’ reactions of the nervous system.

A hormone triggered cells will usually react for a longer period of time

Hormones are ideal for controlling long-term activities such as reproduction, growth and development.

Systems working togetherBoth the nervous system and the endocrine

system respond to a stimulus.Sometimes they work together, as in the case

of fear. The nervous system responds quickly, the shock/surprise reaction and the endocrine system prepares the body for a long term response of fight or flight by releasing adrenalin into to blood stream.

Systems working togetherThe pituitary gland, located at the base of the

brain is considered the ‘master’ gland. It has influence on the function of many of the body's other glands.

The Pituitary gland receives messages directly from the brain, providing a connection between the nervous and endocrine systems.

Examples of chemical controlControlling growthControlling glucose levelsDiabetesPheromones

GrowthGrowth is controlled by the hypothalamus,

pituitary and thyroid glands.A number of hormones are required for

growth, imbalances in these can cause developmental problems of both a physical and mental nature.

Some hormones are, TSH, thyroxin and HGH.

DiabetesA disease in which the blood glucose levels

are not maintained in the required range for healthy living.

Type I and type II.

PheromonesThese are chemicals released into the

environment by an animal to affect the behaviours and or development of others around it.

To attract a mateTo mark territoryTo mark food trails

ActivityConsider the messages relayed by the

endocrine system compared with messages relayed by the nervous system.

List 5 or more examples of each.Suggest reasons why the body would have

two different messaging systems.

Homework page 147 Q 1 - 13