1. The Anatomy and Physiology of
The Nervous
System
Dr Ashwini Kalantri

2. Nervous System
Central Nervous Peripheral Nervous
System System
Motor Sensory
Brain Spinal Cord Neurons Neurons
Somatic Autonomic
N.S. N.S.
Sympathetic
Parasympathetic

3. Sympathetic Nervous
System
Fight or flight
Organ Effect
Eye Dilates pupil
Heart Increases rate and force of contraction
Lungs Dilates bronchioles
Blood Vessels Constricts
Sweat Glands Activates sweat secretion
Digestive tract Inhibits peristalsis
Penis Promotes ejaculation

4. Parasympathetic Nervous
System
 Works opposite to the sympathetic
nervous system
 Tries to keep the body at rest.

5. Functions of the Nervous System
Sensory Function
 Sensory receptors gather information
 Information is carried to the CNS

6. Functions of the Nervous System
Motor Function
 Decisions are acted upon
 Impulses are carried to effectors

7. Functions of the Nervous System
Integrative Function
 Sensory information used to create:
 Sensations
 Memory
 Thoughts
 Decisions

8. Neural Cells
Cell types in neural
tissue:
 Neurons
 Neuroglial cells
(also known as
neuroglia, glia, and glial)

9. Neurons

10. Myelination of Axons
White Matter
 Contains myelinated axons
 Considered fiber tracts
Gray Matter
 Contains unmyelinated
structures
 Cell bodies, dendrites

11. Multipolar Bipolar Unipolar

12. How does the nerve
transmit a signal?

13. Cell Membrane Potential
 A cell membrane is usually electrically charged, or
polarized, so that the inside of the membrane is
negatively charged with respect to the outside of the
membrane.
 This is as a result of unequal distribution of ions on
the inside and the outside of the membrane.

14. Distribution of Ions
 Potassium (K+) ions are the major intracellular
positive ions (cations).
 Sodium (Na+) ions are the major extracellular
positive ions (cations).
 This distribution is largely created by the
Sodium/Potassium Pump (Na+/K+ pump).
 This pump actively transports sodium ions out of
the cell and potassium ions into the cell.
 Also due to the presence of ion-selective channels

15. Resting Potential
Resting Membrane Potential (RMP):
 It is a polarized membrane
 Inside of cell is negative relative to the outside of
the cell, due to distribution of ions inside vs. outside
 Na+/K+ pump restores 70 mV difference from
inside to outside of cell
 RMP = -70 mV

16. Local Potential Changes
 Caused by various stimuli:
 Temperature changes
 Light
 Pressure
 Environmental changes affect the membrane
potential by opening a gated ion channel
 Channels are 1) chemically gated, 2) voltage
gated, or 3) mechanically gated

17. Local Potential Changes
 If membrane potential becomes more negative, it has
hyperpolarized
 If membrane potential becomes less negative, it has
depolarized
 Graded (or proportional) to intensity of
stimulation, meaning the greater the stimulation, the
greater the depolarization
 If the depolarization is great enough, reach threshold
potential
 Reaching threshold potential results in a nerve
impulse, starting an action potential

18. Action Potentials
+40
Action potential
+20
Membrane potential (millivolts)
0
–20
Resting potential
reestablished
–40
Resting
potential
–60
–80
Hyperpolarization
0 1 2 3 4 5 6 7 8
Milliseconds

19. Pathways

20. Dr Ashwini Kalantri
+91 9860598097
cell phone
ak@ashwini.co.in
email