Nervous System Overview

Nervous System

• Composed of three basic components: brain, spinal cord, and neurons.
• Central Nervous System (CNS): Composed of the brain and spinal cord. It acts as the command center, integrating sensory information and generating responses.
• Peripheral Nervous System (PNS): Consists of cranial nerves and spinal nerves, connecting the CNS to the body organs via sensory receptors. It carries signals through nerve impulses (electrical messages).
• Neurons (Nerve Cells): Basic units of the nervous system. Specialized cells transmitting nerve impulses between parts of the body. They have a cell body (soma), dendrites (receivers), and axons (transmitters) with axon terminals.

Neuron Structure and Function

• Cell Body(Soma): Contains the nucleus and organelles.
• Dendrites: Receive signals from other neurons.
• Axon: Transmits signals away from the cell body.
• Axon Terminals: Contain neurotransmitters (chemical messengers).
• Synapse: Gap between axon terminals of one neuron and dendrites of another. Neurotransmitters transmit signals across the synapse.
• Myelin Sheath: Whitish fatty material insulating axons, speeding up nerve impulse transmission.

Functional Neurons

• Sensory Neurons: Transmit signals from sensory receptors to the CNS.
• Motor Neurons: Transmit signals from the CNS to effector organs (muscles and glands).
• Interneurons: Connect sensory and motor neurons.

Structural Classifications of Neurons

• Multipolar: Multiple dendrites and one axon; common type.
• Bipolar: One dendrite and one axon
• Unipolar/Pseudo-unipolar: Single axon extending from the cell body.

Central Nervous System (CNS)

• Brain and spinal cord
• Brain: Largest and most complex mass of nervous tissue. Controls complex functions including intelligence, emotions, learning and critical thinking. Divided into four lobes (frontal, temporal, occipital, parietal).
• Spinal Cord: Transmits information between the body and the brain.

Peripheral Nervous System (PNS)

• Cranial nerves: Originate from the brain, connect to head, neck, and trunk areas. Connect brain to head region.
• Spinal nerves: Originate from the spinal cord, connecting to the limbs and other parts of the body.

Autonomic Nervous System

• Involuntary control of organs.
• Divided into sympathetic ("fight or flight") and parasympathetic("rest and digest") divisions.

Four Major States of Nerve Impulse

• Polarization: Resting state with unequal distribution of ions inside and outside the neuron.
• Depolarization: Stimulation causing a change in potential across the membrane.
• Propagation: Action potential spreading across the axon membrane.
• Repolarization: Restoring the original electrical charge distribution.

Reflexes

• Rapid, involuntary responses to stimuli. Occur without conscious control. Follow a specific pathway (reflex arc).

Endocrine System

• Composed of glands producing hormones regulating various bodily functions.
• Key Glands: Pituitary, Hypothalamus, Thyroid, Pancreas, Adrenal glands. Gonads (testes and ovaries) and others

Reproductive System

• Male and female reproductive systems differ in their structures and functions. Essential for reproduction.

Nervous System Summary

• Includes the CNS (brain and spinal cord) and PNS (nerves).
• Neurons transmit signals via electrical and chemical processes.
• The endocrine system influences nervous system activity via hormones.
• Multiple organs interact for reproduction.

Explore the fundamentals of the Nervous System, including its main components, the Central and Peripheral Nervous Systems, and the structure and function of neurons. This quiz will deepen your understanding of how signals are transmitted in the body and the roles of various neuron parts.