detecting+and+responding+glossary

This section is for you all to keep an up to date glossary of the relvant terminology we cover in this area of study. It is important that you use your own words to explain the meaning of any terms.

Now, your attempt at area of study one was pretty good but don't forget about revisiting that page and adding more terms (there are still a number that need to be added). There will be many more in this area of study and most of them will be new to you.

**NEUROTRANSMITTERS** – are chemicals secreted from axon terminal buds which pass across the synaptic gap (containing tissue fluid) to stimulate the cell membrane of an adjacent neuron or muscle cell. **NEUROHORMONES** – are chemicals secreted from nerve cells, however they differ from neurotransmitters in that they can be released into the bloodstream to exert an effect on a target organ. Essentially, neurohormones function in the same way as other animal hormones. **TROPISMS** – the term tropism refers to plant growth in response to a stimulus such as water or light. Tropisms are termed to be positive if the plant grows towards the stimulus and negative if the plant grows away from the stimulus. **HUMORAL IMMUNITY** - Specific response to foreign antigens. it involves the production of antibodies by plasma cells, leading to the destruction of pathogens. (also called antibody-mediated immunity)
 * HOMEOSTASIS:** the maintenance of a constant internal environment (immediate surroundings of cells) in response to changes in the external or internal environment
 * THRESHOLD STIMULUS -** the weakest stimulus to which a receptor can respond
 * NEGATIVE FEEDBACK** - exists to maintain relatively stable conditions by bringing about a change, which reduces the condition that acted as the stimulus.
 * EFFECTORS -** cells or tissues that are stimulated to respond to a stimulus
 * HORMONES** - chemical messengers produced in one part of the body (by a gland) in response to a stimulus. They travel in the blood stream (or locally in the extracellular fluid) to a particular organ called a target organ, where they have their effect.
 * PHEROMONES** - chemicals produced in the exocrine glands of animals, especially insects, which are then secreted to the external environment to influence the behaviour of other members of that species.
 * ENDOCRINE SYSTEM -** a ductless system compromising a series of glands (some within organs), which release their hormones directly into the blood stream.
 * NERVOUS SYSTEM** - a communication system between different parts of a multicellular organism that uses electrical signals that travel through an intricate network of nerves (neurons).
 * SIGNALLING MOLECULE -** a chemical involved in transmitting information between cells, either locally on nearby cells, systematically by travelling throughout the body, or externally where it may interact with cells in another organism.
 * SIGNAL TRANSDUCTION** - refers to the series of events that occur after the receipt of a specific signal and which result in a response
 * SECOND MESSENGER -** A chemical compound within a cell that is responsible for initiating a signal transduction pathway in response to a signal from a chemical messenger that cannot enter the target cell.
 * CENTRAL NERVOUS SYSTEM -** consists of the brain and spinal cord. Receives and processes sensory information from the Peripheral Nervous System, then coordinates an appropriate response carried out by the motor neurons of the Peripheral Nervous System
 * PERIPHERAL NERVOUS SYSTEM -** the entire network of nerves connecting the Central Nervous System to the rest of the body. It is made up of sensory (afferent) nerves that carry messages from sensory receptors to the Central Nervous System, and motor (efferent) nerves that relay the appropriate response from the Central Nervous System to a particular effector organ or gland
 * AUTOCRINE HORMONE -** A hormone that acts on the cell that it is secreted from
 * PARACRINE HORMONE -** A hormone that is secreted by a cell into the blood stream and travels to a target cell that is nearby
 * ENDOCRINE HORMONE -** A hormone that is secreted by a cell into the blood stream and travels to a more distant target cell somewhere else in the body
 * GUARD CELLS** - Two cells that surround and regulate the opening and closing of the stomata by turgidity
 * ENDOTHERM -** An animal that is able to maintain a relatively constant internal body temperature, due to the presence of internal heat-generating mechanisms. These animals generally have a body temperature that is above that of the temperature of their surrounding environment. They are able to better cope with changing environmental conditions.
 * ECTOTHERM -** An animal whose body temperature fluctuates according to the temperature of their surrounding environment. They adapt to the changing conditions in order to survive, as they are at the mercy of the environmental conditions. eg. Lizards bask in the sunlight to gain heat.
 * OSMOREGULATOR -** An organism that is able to maintain relatively stable body fluid concentration, despite changing external solute concentrations. Energy must be expended by the organism in order to maintain the stable levels of ions and solutes within their body.
 * OSMOCONFORMER -** An organism that does not have the ability to regulate the concentration of their body fluids, and therefore has internal concentrations of ions and solutes that are around the same as those of their surrounding environment.
 * PATHOGEN** - a parasite, microorganism or other agent which can produce an infectious disease in an organism.
 * NON-SPECIFIC IMMUNITY** - refers to the basic resistance to disease that an organism possesses. It is an innate form of immunity and acts the same way irrespective of the invading pathogen.
 * ANTIGEN** - any molecule, usually a protein or glycoprotein which are found in toxins of pathogens or on the surface of pathogens, which can be recognized by a specific antibody