the endocrine system

• Hormones are chemical messengers.
• Hormones are made in endocrine glands and secreted into the blood. The blood transports the hormones in the plasma around the body.
• Hormones cause a response in specific cells that are found in target organs.
• Hormones regulate the functions of many cells and organs.
• Normally, hormonal responses are fairly slow and long lasting.
• Testosterone is responsible for stimulating sperm production in males.
• Some hormonal responses can act more quickly (when adrenaline is released in response to danger, the body is affected within a few seconds).
• Hormones control body processes that need constant adjustment - such as body temperature.
• Keeping the conditions in your body constant is called homeostatis.
• The hypothalamus and pituitary gland produce hormones that regulate production of other hormones.
• The thyroid gland produces thyroxine.
• The adrenal gland produces adrenaline.
• The pancreas produces insulin.
• The ovaries produce oestrogen and progesterone.
• The testes produce testosterone.
• Nerve impulses travel to specific parts of the body.
• Hormones travel all over the body in the bloodstream however only target organs respond.
• Hormones diffuse out of the blood and bind to specific receptors for that hormone found on the membranes or in the cytoplasm of cells in the target organs - these are known as target cells.
• Once bound to their receptors the hormones stimulate the target cells to produce a response.
• The endocrine system is all the endocrine glands and the hormones they produce.
• The endocrine system controls and coordinates body processes with the nervous system.
• The endocrine and nervous system send messages around the body to provide information about any changes in your internal and external environment.
• The endocrine and nervous system send information as to how the body should respond.
• Nervous system: very fast speed of communication, transmitted by electrical impulse along the axon of a neurone, short acting response, very precise target area.
• Hormones: slower speed of communication, transported in the blood, long acting response, larger target area.