RBSE Class 11 Biology Notes Chapter 21 Neural Control and Coordination

These comprehensive RBSE Class 11 Biology Notes Chapter 21 Neural Control and Coordination will give a brief overview of all the concepts.

RBSE Class 11 Biology Chapter 21 Notes Neural Control and Coordination

→ Nervous system is present to establish neural control and coordination.

→ Nervous system consists of nerve cells called neurons and it is made up of—central nervous system (CNS), peripheral nervous system (PNS) and autonomic nervous system (ANS).

→ CNS consists of brain and spinal cord.

→ Brain is lodged in cranial cavity and protected by bony skull, three meninges and cerebrospinal fluid.

→ Brain is divisible into three parts:

1. fore brain,
2. mid brain,
3. hind brain.

→ The medulla oblongata of the hind brain extends and comes out of the brain/skull forming a spinal cord which is protected and is in neural canal of back bone.

→ Neurons are:

• Structurally divided into: Non-polar, unipolar, bipolar, multipolar.
• Functionally divided into: Motor nerves, sensory nerves.
• In presence of myelin sheath: Myelinated and non-myelinated nerves.

→ Nerve impulse is an electro-chemical event that occurs due to change in concentration gradient of Na+ and K⁺ ions on the nerve cell.

→ The reflex response to an external stimulus/ environment without thought is called reflex action. e.g., jerk of knee, removal of finger from hot/cold object.

→ The nerve impulse is generated by action potential due to influx of Na⁺ inside and outflux of K⁺ bn the neurolemma. Which propagates throughout the axon.

→ There are five sense organs: Eye, ear, nose, tongue and skin.

→ Eye has three layers-sclera, choroid, retina. Retina has rod and cone cells. Anterior part of eye has a transparent cornea, pigmented iris, an aperture pupil. Optic nerve emerges out from the eye.

→ Ear has three parts: External, middle, internal ear. The ear ossicles (smallest bones) are present in middle ear and internal ear has bony labyrinth, membranous labyrinth.

→ Neurons: The nerve cells.

→ Neuroplasm: The cytoplasm of the nerve cells.
 
→ Meninges: The protective membranes of the CNS.

→ Cerebrospinal Fluid: The fluid present in the cavities of the CNS.

→ Nerve Impulse: The disturbance caused due to the electrical chemical changes in the nerve cell.

→ Synapsis: The junction between-Axon terminals of one neuron with dendrites with another neuron.

→ Iris: The pigmented part of the eye visible from outside.

→ Blind spot: The spot where no image is formed on retina.

→ Yellow spot: The spot where the image formed is brightened.

→ Rhodopsin: The pigment (visual purple) present in rod cells.

→ lodopsin: The pigment present in cone cells.

→ Cochlear duct: The terminal coiled part of the internal ear.

→ Organs of Corti: The portion that senses hearing. 

→ Maculae: The group of sensory cells present in utriculus and sacculus.