This document provides an overview of the nervous system. It describes the nervous system as having two main parts: the central nervous system (CNS), comprising the brain and spinal cord, and the peripheral nervous system (PNS). The CNS acts as the integration and command center, while the PNS connects it to the rest of the body. Neurons are the basic functional units and come in sensory, motor, and interneuron types. The document also outlines the anatomical organization and basic functions of the nervous system, including integration at different levels and the roles of neuroglia like oligodendrocytes and Schwann cells.

1. Introduction
to
Nervous System
DR. KARISHMA R. PANDEY
ASSISTANT PROFESSOR
DEPARTMENT OF BASIC AND CLINICAL PHYSIOLOGY

2.  General organization of the nervous system
 Basic neuronal organization for functions
o Sensory
o Integration
o Motor
 The basic functional unit of the nervous system

3. Anatomical Organization of the
Nervous System
 Central nervous system (CNS)
• consists of the brain located within the skull
and the spinal cord located within the vertebral
foramen
• integration and command center of the body
 Peripheral nervous system (PNS)
• consists of nerves (extensions of the CNS) that
connect the CNS to all other locations in the body
 Autonomic nervous system
• regulates and controls visceral functions, including
heart rate, blood pressure, digestion, temperature
regulation, and reproductive function.

4. Basic neuronal organization for functions
Three Basic Functions
1. Sensory Functions: Sensory receptors detect both internal and
external stimuli.
Functional unit: Sensory or Afferent Neurons
2. Integrative Functions: CNS integrates sensory input and makes
decisions regarding appropriate responses
Functional Unit: Interneurons or Association Neurons of the Brain
and Spinal cord
3. Motor Functions: Response to integration decisions.
Functional Unit: Motor or Efferent Neurons

6. Functional Organization of the PNS
Figure 14.1

10.  Integration at the level of spinal Cord: Reflexes
 withdraw portions of the body from painful objects,
 stiffen the legs to support the body against gravity

11. Reflex arc:
Receptor afferent N center (Brain/Spinal cord) efferent N muscle/gland.

12. Integration at the level of lower brain
 Control of equilibrium is a combined function of the
cerebellum, reticular formation of medulla, pons and
mesencephalon
 Body temperature, feeding and drinking behavior, hormonal
secretion are regulated by hypothalamus
 Fear, rage, anxiety and sexual behavior are controlled by
limbic system
 Coordination of motor functions are done by cerebellum and
basal ganglia

13. Integration at the level Cerebral cortex
Sensory perception, speech, cognition, learning and memory, motor planning and
voluntary movement

14. Cells of the Nervous System
two principal cell types
– Neurons
– Neuroglia

15. Neuron

16. Types of Neurons

18. Schwann cells PNS Surround axons of all peripheral nerve fibers, forming a
neurilemmal sheath, or sheath of Schwann; wrap around many peripheral fibers to
form myelin sheaths; also called neurolemmocytes
Satellite cells PNS Support functions of neurons within sensory and autonomic
ganglia; also called ganglionic gliocytes
Oligodendrocytes CNS Form myelin sheaths around central axons, producing “white
matter” of the CNS
Microglia CNS Phagocytose pathogens and cellular debris in the CNS
Astrocytes CNS Cover capillaries of the CNS and induce the blood-brain barrier;
interact metabolically with neurons and modify the extracellular environment of
neurons
Ependymal cells CNS Form the epithelial lining of brain cavities (ventricles) and the
central canal of the spinal cord; cover tufts of capillaries to form choroid plexuses—
structures that produce cerebrospinal fluid

20. Myelin Sheath Formation

22. Supporting cells: neuroglia
 Oligodendrocytes: myelin formation around axons in the CNS
 Schwann cells: myelin formation around axons in PNS
 Astrocytes: send processes to blood vessels, make up the blood–brain barrier
 Microglia: are scavenger cells that resemble tissue macrophages and remove debris
resulting from injury, infection, and disease (eg AIDS-related dementia, Parkinson
disease, and Alzheimer disease).
Dr Rita Khadka