This document provides an overview of applied physiology of the nervous system. It begins with an introduction to the central nervous system, including its organization and main parts like the brain and spinal cord. Key concepts covered include the structure and functions of neurons and neuroglia. The roles of gray and white matter are discussed. Main functions of the central nervous system include temperature regulation, spinal cord reflexes, memory and learning, and voluntary movement. Imaging techniques for the central nervous system are also mentioned. The document goes on to explain topics like resting membrane potential, action potentials, synaptic transmission, and the reflex arc.

2. Course Name:
Applied Physiology
Course code: BMIS 3rd Sem, BSMUT Ist Sem
By
Capt Dr. Kashifa Ehsan
Assistant Professor Physiology
URISMIT-UOL

3. Applied Physiology of Nervous System
(Content)
• Introduction and Organization of CNS
• Sensory & Motor System
• Functions of different parts of CNS

4. Learning Outcomes
At the end of this lecture you will have the knowledge of:
 Introduction of Nervous System
 Neurophysiology
 Functions of Nervous system
 Parts of Nervous System
 What is neuron
 Supporting cells of Nervous System

5. Organs of CNS
• Brain
• Spinal Cord
• Nerves

7. Nervous tissue
The nervous tissue is made of two types of cells:

 Neuroglia
 Neurons

8. Neuroglia
■ These are non- excitable connective tissue cells forming interstitium
■ Present in both gray and white matters.

9. Function of Neuroglia of CNS
■ Astrocytes( largest)  Formation of blood-brain barrier
■ Oligodendroglia  Myelination in CNS
■ Microglia  Phagocytosis
■ Ependymal cells  CSF formation

10. Contd:
• Support.
• Insulation
• Neuroglia of PNS is Schwann cells.

11. Neurons = Nerve cells
■ Neurons are the structural and functional unit of the nervous system.
■ After birth neruons cannot divides, so if they die they cannot be
replaced.

12. Structure of neurons
1. Soma or Cell body with:
■ Large vesicular nucleus with a single prominent nucleolus, mitochondria and other
organelles.
■ Abundant rough endoplasmic reticulum( RER), reflecting high rate of protein
synthesis.
2. Dendrites
3. Axons

13. Gray Matter and White Matter
Gray Matter:-
■ It is composed of nerve cell bodies embedded in neurolgia.
White Matter:-
■ It is composed of nerve fibers embedded in neuroglia. White
apperance is due to myelin sheath.

15. Main functions of CNS
The four main functions of the nervous system are:
• Control of body's internal environment like the regulation of body
temperature. ...
• Programming of spinal cord reflexes. An example of this is the stretch
reflex. ...
• Memory and learning. ...
• Voluntary control of movement.

17. Imaging techniques relevant to imaging of
the central nervous system include:
• MRI.
• CT and CT angiography (CTA)
• digital subtraction angiography (DSA)
• cranial ultrasound.
• skull x-ray.

19. NeuroPhysiology
• Neuron is an electrochemical machine,
• Neuronal functions: Electrical events + Biochemical + Molecular
processes
• To study neurons, neurophysiologists use techniques of:
a) Chemistry (calcium imaging)
b) Physics (functional magnetic resonance imaging, fMRI)
c) Molecular biology (site directed mutations) to study brain function

20. Resting Membrane and Action Potential
• In the resting state, the neuronal cell membrane is impermeable to ions
generating resting membrane potential (RMP)
• The major intracellular ion is Potassium (K+)
• Sodium (Na+) is in the extracellular fluid.
• Na+ enters while K+ leaves the cell along concentration gradients and This
movement of ions out of the cell leads to a negative membrane potential -
Hyperpolarisation.

22. Action Potential
• Defined as a "single electrical impulse passing down an axon".
• Threshold Stimulus Intensity: The value at which the net inward
current(determined by Na+ ions) is just greater than the net outward
current (carried by K+ ions).
• It is normally -55mV (critical firing threshold)

23. Neuromuscular Junction / Synapses
Synapse
• A synapse is the junction of two neurons.
• The chemical synapse is found in the nervous system
• Electrical synapses are found in cardiac muscle and glial cells.
•

24. Neuromuscular junction
■ A neuromuscular junction (or myoneural junction) is
a chemical synapse between a motor neuron and
a muscle fiber.
■ It allow the motor neuron to transmit a signal to the
muscle fiber, causing muscle contraction.
■ It is also known as neuromuscular transmission.

27. Synaptic Transmission
• Action potential arrives  depolarisation of the presynaptic
terminal opening up of Ca2+ channels Influx of Ca2+  liberates
the vesicle  releases neurotransmitters into the synaptic cleft.
• Released neurotransmitter diffuses across synaptic cleft and binds to
the postsynaptic receptor.
• Activation of the postsynaptic receptor leads to a change in the
postsynaptic membrane potential.

28. Nerve Conduction
• Action potential propagation is achieved by local current spread.
• Thin fibers of neuron called axons, communicate with other cells by
releasing chemicals called neurotransmitters at cell-cell junctions
called synapses.
• The nerve is insulated with myelin if its size is above a certain
diameter, with the Nodes of Ranvier at various intervals along its
length.

30. • NEURON

31. Sensory Input
• Sensory input comes from the many sensory receptors through
stimulus
• Stimulus: Information of changes in both inside and outside the body
• Neurotransmitters: The neurotransmitter is released at the synapse
and works with a specific protein
• Receptors: Specific protein in the postsynaptic membrane
• Afferent Nerve: Information from receptors travel in nerves

32. Central Nervous System
Integration
• The nervous system receives  processes  interprets sensory input
and decides & determines an appropriate response.

33. Motor Response
• Once the response is activated, the nervous system sends signals via
motor output to effector organs muscles or glands to initiate the
response.

34. Parts of reflex arc
■ Receptor:- Ending of afferent fiber. receives impulse.
■ Afferent neuron:- From receptor to CNS carries
impulse from receptor to CNS.
■ Interneuron:- Inside CNS it interprets received
impulse.

36. Reflex arc
■ A reflex arc is a neural pathway that controls an action
reflex .
■ most sensory neurons do not pass directly into the
brain but synapse in the spinal cord.
■ Synapses:- i.e contact between two neurons.
■ Efferent neuron:- From CNS to effector organ. Carries
“command” from CNS to effector organ.

37. ■ This characteristic allows reflex actions to occur relatively quickly by
activating spinal motor neurons without the delay of routing signals
through the brain, although the brain will receive sensory input while
the reflex action occurs.

44. Reference
1.Guyton and Hall Textbook of Medical Physiology- 13th Edition
2.BRS (BOARD REVIEW SERIES)-7th edition
3.13th EditioBRS (BOARD REVIEW SERIES)-7th
editionhttps://youtu.be/0yXMGQaVVXg