5. Responses in Animals (chemical mediators) Flashcards
Define chemical mediator
(part of paracrine signalling) a chemical messenger, released from certain mammalian cells, that act on nearby cells
Name 3 differences between hormonal communication and chemical mediators
- chemical mediators are secreted from cells that are all over the body (not just from glands)
- their target cells are right net to were the chemcical mediator’s produced. They stimulate a local response (not a widespread one)
- They only have to travel a short distance to their target cells, so produce a quicker response than hormones (which are transported in the blood)
Name 8 differences between the hormonal and nervous system
Communication by chemicals/by nerve impulses
Transmission by blood/neurones
Transmissio is slow/rapid
Hormones travell all over body, target cells respond/nerve impulses travel to specific parts of the body
Response is widespread/localised
Response is slow/rapid
Response is often long lasting/shortlived
Effect may be permanent and inrreversible/temporary and reversible
Describe the inflammatory response
Chemical mediators re;eased by infected or injured cells and cause small arteries and arterioles to dilate. This leads to a rise in temperature and swelling of the affected area
Where is histamine stored?
When is it released?
What does it cause?
Why is this a useful response?
- stored in certain white blood cells
- released following injury or in response to an allergen
- causes dilation of small arteries and arterioles, increases permeability of capillaries, leading to localised swelling, redness and itching
- allow plasma and leukocytes to reach the injury
Where are prostaglandins found?
When are they released?
What do they cause?
- found in cell membranes
- released following injury
- cause dilation of small arteries and arterioles, increase permeability of capital, affect blood pressure and neurotransmitters, affect pain sensation
