Coordination Through Chemicals

Coordination• As cells become specialised to perform a specific function, they

lose the ability to carry out other tasks.

• They become dependent on other cells/tissue to provide them with oxygen/glucose or remove their waste, so they can concentrate on their main role.

• All the different functional cells/tissues/organs/systems need to be coordinated if the organism is to perform efficiently.

• All body systems must be integrated in a coordinated fashion.

Principles of Coordination

• Nervous system is one main way of cells/tissue communicating with each other in a rapid way.

• Involves electrical impulses and the responses are short-lived and restricted to a localised part of the body.

Principles of Coordination

• Hormonal System produces chemicals (hormones) that are carried in the blood plasma to target cells.

• Slower, less specific form of communication.

• Responses are longer-lasting.

• Example – control of blood glucose levels by insulin/glucagon.

Coordination

• The nervous and hormonal systems work together and interact with one another.

• Think of nervous system as email or telephone conversation between 2 specific people.

• Hormonal system is like a letter of invitation being sent out en mass via postal system and only specific people replying.

Chemical Mediators• Chemicals released by mammalian cells that affect cells close around

them (more localised than hormonal control).

• Usually released by damaged or infected cells that spread to other local cells by diffusion (as opposed to hormones that travel in the blood to target cells).

• They can cause arteries/arterioles to dilate and capillaries to become more permeable allowing wbcs to squeeze out.

• More blood can come into the infected area.

• Leads to “inflammatory response”.

Chemical Mediators• Histamine – stored in white blood cells and released

following injury or in response to an allergen.

• Prostaglandins – Type of lipid found in cell membranes. Released following injury. They cause muscle contractions, affect blood pressure and neurotransmitter release at the pain synapses. Therefore they affect can induce child labour and are involved with pain sensation.

• Aspirin is a pain killer that works by inhibiting the production of prostaglandins.

Anaphylaxis

• Usually happens to people who are known to have an allergy.

• Peanuts and tree nuts (such as almonds, Brazil nuts, hazelnuts and walnuts) are the foods most likely to provoke a reaction. Anaphylaxis can also be triggered by fish, shellfish, eggs and cow's milk.

• Allergy to from bee and wasp stings can cause anaphylaxis too, as can allergy to latex rubber and drugs such as antibiotics

• The initial reaction is swelling and itching of the area the allergen has entered.

• Food initially causes swelling and itching of the mouth and throat, while a wasp sting will cause intense itching and swelling around the sting

• A generalised reaction rapidly follows within minutes and a raised itchy rash spreads over the whole body. The face and soft tissues begin to swell and breathing becomes difficult as the throat closes

• An injection of adrenaline must be given to raise blood pressure, relieve breathing difficulties and reduce swelling