Revision: Control and Co-ordination Science English Medium Class 10 CBSE

The neurons which carry impulses from the body parts to the spinal cord or the brain are called sensory or afferent neurons. For example, the optic nerve of the eye.

Neurons are the building blocks of the nervous system and transmit information throughout the body.

A stimulus is an agent or a sudden change in the external or internal environment that changes an organism or body parts. e.g., light, sound, heat, pain, hunger.

The path that an impulse takes in a reflex action is called a reflex arc.

The neurons which carry impulses from the brain or spinal cord to the body parts are called motor or efferent neurons.

Receptors are specialised sensory cells that receive stimuli and convert them into nerve impulses.

Effectors are muscles or glands that produce a response by contracting or secreting substances when stimulated by nerve impulses.

A neuron is a specialised cell that forms the structural and functional unit of the nervous system and is responsible for transmitting nerve impulses.

Neurolemma is the outermost thin protective sheath covering the myelin sheath of a nerve fibre.

Nodes of Ranvier are gaps present at intervals in the myelin sheath that help in faster transmission of nerve impulses.

Axon terminals are closely placed near the dendrites of another one or more neurons but are not connected. Such gaps in between are called synaptic clefts.

A stimulus is any sudden change in the internal or external environment that brings about a response in an organism.

A nerve is a bundle of axons from numerous neurons encased in a protective sheath.

Axon terminals are closely placed near the dendrites of another one or more neurons but are not connected. Such gaps in between are called synaptic clefts.

A response is the reaction or change in an organism produced as a result of a stimulus.

A nerve impulse is an electrical disturbance that travels along a neuron in response to a stimulus.

Synapse (syn: together, apse: gap/window) is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap.

or

The junction between two nerve cells having a minute gap called synaptic cleft through which nerve impulse is transmitted by neurotransmitters is called synapse.

Nerve is a bundle of nerve fibres (axons) of separate neurons, enclosed in a tubular sheath.

It is an automatic/quick/immediate, involuntary action in the body brought about by a stimulus.

Reflex action is an automatic/quick/immediate, involuntary action in the body brought about by a stimulus. This mechanism prevents injury to the body by triggering a rapid and automatic response.

A reflex arc is the shortest route that can be taken by an impulse from a receptor to an effector.

The brain is protected by 3 membranous coverings called meninges (meninx: membrane) which continue backwards on the spinal cord.

Inflammation of the meninges is called meningitis.

Growth movements occurring in response to unidirectional external stimuli in a plant part are called tropic movements.

The direction of the response is related to the direction from which the stimulus comes. Such a response is known as tropism.

The term "tropic" comes from a Greek word "tropos" which means to "turn'.

Phototropism is the directional growth of a plant in response to light.

Positive phototropism is when a plant part, like a shoot, grows towards a light source.

Geotropism (also called gravitropism) is the directional growth of a plant in response to Earth's gravity.

Positive geotropism is when a plant part, such as a root, grows in the direction of gravity (downward).

Negative geotropism is when a plant part, such as a shoot, grows against the direction of gravity (upward).

Hydrotropism is the directional growth of a plant part in response to water or moisture.

Positive hydrotropism is when a plant part, such as a root, grows towards the source of moisture.

Thigmotropism is the directional growth of a plant part in response to touch or contact with a solid object.

Chemotropism is the growth movement of plant parts in response to chemicals.

1. Voluntary actions are performed consciously, while involuntary actions (reflexes) occur automatically without conscious control.
2. A stimulus is any change in the environment that initiates a reflex action.
3. Reflex actions are quick, automatic responses to stimuli and do not require conscious thought.
4. Examples of reflexes include withdrawal of hand from a hot object, shivering in cold, and sweating in heat.
5. All reflexes are triggered by sensory stimulation and result in either muscular movement or glandular secretion.

1. Plants do not have a nervous system or muscles, but they can still respond to stimuli like touch and light.
2. Plant movements are of two types – one independent of growth (like in the touch-me-not plant) and the other dependent on growth (like seedling movement).
3. In immediate response (like leaf folding), no growth occurs; the response is quick and due to electro-chemical signals passed from cell to cell.
4. Movement in plants happens by changing water content in cells, causing them to swell or shrink, unlike animal muscles which use proteins.

1. Hormones are chemical messengers that help in control and coordination by carrying signals through the blood to different parts of the body.
2. Adrenaline helps the body to face stress or danger by increasing heart rate, breathing, and sending more blood to muscles.
3. Thyroxin, made by the thyroid gland, controls the body’s metabolism; iodine is needed to make thyroxin, and its lack can cause goitre.
4. The pituitary gland makes growth hormone, which controls height and body growth; too little of it in childhood causes dwarfism.
5. Insulin, made by the pancreas, controls blood sugar levels; its shortage causes diabetes, and insulin injections help control it.