Neural Control and Coordination - Exercises

1. Briefly describe the structure of the Brain. Answer: The human brain is divided into three major parts:

Forebrain: Consists of the cerebrum (largest part), thalamus (sensory/motor signaling centre), and hypothalamus (controls temperature, hunger, and thirst).
Midbrain: Located between the forebrain and hindbrain; contains the cerebral aqueduct and corpora quadrigemina (four round swellings).
Hindbrain: Comprises the pons (interconnects brain regions), cerebellum (convoluted surface for more neurons), and medulla oblongata (controls respiration and cardiovascular reflexes).

2. Compare the following: (a) CNS and PNS: CNS includes the brain and spinal cord (information processing); PNS comprises all nerves associated with the CNS. (b) Resting potential and Action potential: Resting potential is the electrical potential difference across the membrane of a non-conducting neuron; Action potential is the electrical potential difference generated when a stimulus is applied, also called a nerve impulse.

3. Explain the following processes: (a) Polarisation: In a resting neuron, the axonal membrane is more permeable to K+ and nearly impermeable to Na+, creating a positive charge outside and negative charge inside. (b) Depolarisation: When a stimulus is applied, the membrane becomes permeable to Na+, causing an influx of Na+ and reversing the polarity (negative outside, positive inside). (c) Transmission across a chemical synapse: Neurotransmitters are released from synaptic vesicles into the synaptic cleft, where they bind to receptors on the post-synaptic membrane, opening ion channels.

4. Draw labelled diagrams of the following: (Note: Components are described for textual format) (a) Neuron: Includes cell body (with Nissl’s granules), dendrites (receive impulses), and axon (transmits impulses to synaptic knobs). (b) Brain: Showing Forebrain (Cerebrum, Thalamus, Hypothalamus), Midbrain, and Hindbrain (Pons, Cerebellum, Medulla).

5. Write short notes on the following: (a) Neural coordination: Organised network of point-to-point connections for quick interaction between organs. (b) Forebrain: Site for intelligence, memory, and voluntary control; includes the limbic system for emotions. (c) Midbrain: Involved in visual and auditory reflexes. (d) Hindbrain: Controls vital involuntary functions and maintains body balance. (e) Synapse: The junction between two neurons where impulses are transmitted.

6. Give a brief account of Mechanism of synaptic transmission. Answer: When an action potential reaches the axon terminal, synaptic vesicles release neurotransmitters into the synaptic cleft. These bind to specific receptors on the post-synaptic neuron, generating a new excitatory or inhibitory potential.

7. Explain the role of Na+ in the generation of action potential. Answer: The rapid influx of Na+ ions into the axon upon stimulation causes the reversal of membrane polarity (depolarisation), which creates the action potential or nerve impulse.

8. Differentiate between: (a) Myelinated and non-myelinated axons: Myelinated axons have a myelin sheath formed by Schwann cells with nodes of Ranvier; non-myelinated axons lack this sheath. (b) Dendrites and axons: Dendrites carry impulses towards the cell body; axons carry impulses away from the cell body. (c) Thalamus and Hypothalamus: Thalamus is a coordinating centre for signaling; Hypothalamus regulates homeostatic functions like temperature and thirst. (d) Cerebrum and Cerebellum: Cerebrum is for higher functions like memory; Cerebellum is for motor coordination and balance.

9. Answer the following: (a) Which part of the human brain is the most developed? Cerebrum (b) Which part of our central neural system acts as a master clock? Hypothalamus (involved in circadian rhythms)

10. Distinguish between: (a) Afferent and efferent neurons: Afferent carry impulses to the CNS; Efferent carry impulses from the CNS to tissues. (b) Impulse conduction in myelinated vs unmyelinated: Faster in myelinated due to saltatory conduction between nodes of Ranvier. (c) Cranial nerves and spinal nerves: Cranial nerves arise from the brain; Spinal nerves arise from the spinal cord.

Neural Control and Coordination - Exercises

1. Briefly describe the structure of the Brain. Answer: The human brain is divided into three major parts:

Forebrain: Consists of the cerebrum (largest part), thalamus (sensory/motor signaling centre), and hypothalamus (controls temperature, hunger, and thirst).

Midbrain: Located between the forebrain and hindbrain; contains the cerebral aqueduct and corpora quadrigemina (four round swellings).

Hindbrain: Comprises the pons (interconnects brain regions), cerebellum (convoluted surface for more neurons), and medulla oblongata (controls respiration and cardiovascular reflexes).

Class 11 Biology - Chapter 18 Neural Control and Coordination

Neural Control and Coordination - Exercises

On this page

Class 11 Biology - Chapter 18 Neural Control and Coordination

Neural Control and Coordination - Exercises

On this page