Class 10 Biology Chapter 9
The Nervous System and Sense Organs
Important Questions

Nervous System: The nervous system is a complex network of specialised cells, called neurons, and supportive cells known as neuroglia. It is responsible for transmitting signals or information throughout the body. The nervous system can be divided into two main parts:
a. Central Nervous System (CNS): This includes the brain and the spinal cord. The CNS processes information and coordinates responses to various stimuli. It is the control centre of the body.
b. Peripheral Nervous System (PNS): The PNS consists of nerves that extend from the CNS to all parts of the body. It helps in carrying signals to and from the CNS. The PNS is further divided into the somatic nervous system (responsible for voluntary movements) and the autonomic nervous system (controls involuntary functions like heart rate and digestion).
‍Sense Organs: Sense organs are specialised structures in the body that allow us to perceive and respond to different types of stimuli from the environment. These organs include:
a. Eyes: The eyes are responsible for vision. They contain receptors called photoreceptors that detect light and convert it into electrical signals that the brain interprets as images.
b. Ears: The ears are responsible for hearing and balance. The inner ear contains specialised receptors for detecting sound vibrations and changes in position.
c. Nose: The nose is responsible for the sense of smell. It contains olfactory receptors that detect odour molecules in the air.
d. Tongue: The tongue is responsible for the sense of taste. Taste buds on the tongue detect different flavours like sweet, salty, sour, and bitter.
e. Skin: The skin is the largest sense organ and is responsible for the sense of touch, temperature, and pain. It contains various receptors that transmit these sensations to the brain. The Nervous System and Sense Organs work together to gather information from the environment, process that information, and initiate appropriate responses. This complex and integrated system is essential for our survival and allows us to interact with the world around us in a meaningful way.