Definitions (Stimulation and Reaction)

STIMULATION AND REACTION

Stimulus: A change in the environment that can induce a plant or animal to react or respond is known as stimulus.

Response: The reaction of a plant or animals to the stimulus is called response.

Taxis: The movement of an organism or their parts by changing location under the influence of the stimulus such as light, chemical etc. is called taxis.

Phototaxis: The movement of an organism in response to the stimulus of light is called phototaxis.

Chemotaxis: The movement of an organism in response to the stimulus of chemical is called chemotaxis.

Positive taxis: The movement of an organism towards the stimulus is called positive taxis.

Negative Taxis: The movement of an organism away from the stimulus is called negative taxis.

Positive phototaxis: The movement of an organism towards the stimulus of light is called positive phototaxis.

Negative phototaxis: The movement of an organism away from the stimulus of light is called negative phototaxis.

Positive chemotaxis: The movement of an organism towards the stimulus of chemical is called positive chemotaxis.

Negative chemotaxis: The movement of an organism away from the stimulus of chemical is called negative chemotaxis.

Tropism: The movement of parts of a plant without changing their location in response to the stimulus.

Positive tropism: The movement of parts of plant towards the stimulus.

Negative tropism: The movement of parts of plant away from the stimulus.

Phototropism: The movement of parts of plant in response to the stimulus of light.

Positive Phototropism: The movement of parts of plant towards the stimulus of light.

Negative Phototropism: The movement of parts of plant away from the stimulus of light.

Chemotropism: The movement of parts of plant in response to the stimulus of chemical.

Positive chemotropism: The movement of parts of plant towards the stimulus of chemical.

Negative Chemotropism: The movement of parts of plant away from the stimulus of chemical.

Geotropism: The movement of parts of plant in response to the stimulus of gravity.

Positive geotropism: The movement of parts of plant towards the stimulus of gravity.

Negative Geotropism: The movement of parts of plant away from the stimulus of gravity.

Hydrotropism: The movement of parts of plant in response to the stimulus of water.

Positive Hydrotropism: The movement of parts of plant towards the stimulus of water.

Negative hydrotropism: The movement of parts of plant away from the stimulus of water.

Thermo tropism: The movement of parts of plant in response to the stimulus of heat.

Positive Thermo tropism: The movement of parts of plant towards the stimulus of heat.

Negative Thermotropism: The movement of parts of plant away from the stimulus of heat.

Thigmotropism: The movement of parts of plants in response to the stimulus of touch.

Nervous system: The system that receives the stimulus transmits it to the other parts of the body which show the corresponding effects.

Neuron: The cell that transmit the messages from one part of the body to the other.

Axon: A long and tube like structure which arises from the cell body.

Dendrite: They are short, thin, highly branched fibres which receive impulses from the axons of other neurons.

Ganglion: A mass of nerve cell bodies outside the brain and spinal cord that receives and sends out nerve impulses.

Brain: A highly specialized delicate and hollow organ located inside the skull.

Cerebrospinal fluid: Between the arachnoid and pia mater, there is a cavity called sub-arachnoid space which is filled with a fluid which is called cerebrospinal fluid.

Cerebrum: it is the largest part of the human brain consisting of two cerebral hemisphere.

Cerebellum: it is a well developed part of the brain and lies below the cerebrum and above the medulla oblongata.

Spinal cord: The spinal cord is a long, soft and white jellylike substance present in the neural canal of vertebral column.

Medulla oblongata: It is the lowermost part of the brain which is located between pons Varolii and upper end of vertebral column.

Nerves: A nerve is a group of a bundle of nerve fibres (axon) enclosed in a tubular sheath.

Sensory /Afferent nerve: The nerves that carry impulses from sense organ to the brain or spinal cord are called sensory nerves.

Efferent nerves/ Motor nerves: The nerves that carry impulses from brain or spinal cord to the various parts of the body are called motor nerves.

Mixed nerves: Sometimes, axon of both sensory and motor nerve forms the nerves which are called mixed nerve.

Cranial nerves: The nerves which originate from the brain and carry the nerve impulses to and from the brain.

Spinal nerves: The nerves which originate from the spinal cord and carry the nerve impulses to and from the spinal cord.

Nerve impulses: The information that passes through the neurons in the form of chemicals and electrical signal.

Reflex action: An involuntary action performed by muscles under the direction of the spinal cord in response to the stimulus.

Synapse: The junction points between the two neurons.

Reflex arc: The route taken by the nerve impulses from the receptors to the effectors during the reflex action.

Glands: A group of cells that help in secretion.

Endocrine gland: The glands which do not have any duct and pour their secretion directly into the blood.

Exocrine gland: The glands which have duct and whose secretions are carried by the ducts to the organs.

Hormones: Hormones are the chemical substance which controls, co-ordinate and integrate the function of various organs of the body.

Pituitary gland: It is a small, pea-sized gland at the base of the brain. It is also called the master gland.

Impulses: A wave of electrical disturbance that sweeps over the nerve cells.