1. HUMAN NERVOUS
SYSTEM

2. Human NERVOUS system
 Nervous system controls and regulates the
work of all body parts, from simple finger
movement till very complex heartbeat
 The nervous system contains a complex
network of nerve cells, or neurons.
 Neurons are specialized cells that transmit
information throughout the body.

3. Structure of a neuron
 Dendrites which extend from the
cell body of the neuron, are the
“antennae” of the neuron. Dendrites
receive information from other cells.
 An axon is a long membrane-
covered extension of the cytoplasm
that conducts nerve impulses.
 Its membrane is called as myelin
sheath
 Bundles of axons are called nerves.

5. Neuron structure

6. Types of neurons
 Neurons can be classified according to their
projections and functions:
a. Unipolar – sensory neuron, They transmit
information from sensory organs (eyes, ears, skin,
etc) to the central nervous system.
b. Bipolar - interneurons are generally found in the
central nervous system. Their main function is
interpretation of information.
c. Multipolar - motor neurons carry impulses from
central nervous system to muscles or glands.

9. Neuron function
 Neurons receive and transmit signals
as weak electrical impulses
 These signals are called as nerve
impulses and they travel like wave
from dendrite to axon
 Na+ and K+ ions take role in carrying
impulse.

11. Communication
between neurons
 Neurons communicate
by means of synapse,
where signals are
transmitted from axon
of one neuron to
dendrite of another
 Synapse is a space
between neurons and
there is no direct
connection

13. Neurotransmitters
 Impulse passes from axon of one neuron to
dendrite of another by means of special
neurotransmitters
 Neurotransmitters diffuse across the
synapse and carry impulse from a nerve cell
to another.
 They are released by 1st cell axon end and
received by 2nd cell dendrite
 Examples: adrenaline, histamine,
acetylcholine etc.

17. Parts of human nervous system
 Human nervous system includes 2 parts:
a. Central Nervous System (CNS): includes brain
and spinal cord, control center of body
b. Peripheral nervous system (PNS): contains
sensory neurons, receive information (eye, skin,
ear …) and transmit it to CNS; and motor
neurons which send commands from CNS to
muscles and organs

19. CNS: brain
 Brain, body’s main processing and
controlling center which is protected by skull
and includes about 100 billion neurons
 All body activities, emotions, thought,
memories are controlled by brain
 Its size in males about 1200-1350 grams and
in females 1000-1250 grams

20.  The brain consists of three main
parts:
1. Forebrain
2. Midbrain
3. Hindbrain

23. BRAIN: 1. Forebrain
(передний мозг)
 Largest portion of brain, composed of 2 main parts:
a. Cerebrum (конечный мозг)
 Upper covering part, has many folds, divided into 2
hemispheres
 Responsible for thought, skeletal muscles movement,
skin feel, vision, hearing and smell and etc.
b. Diencephalon (промежуточный мозг)
 Regulates body temperature, responsible for anger,
pain, pleasure, hunger, thirst, also maintains
homeostasis and etc.

26. BRAIN: 2. Midbrain
 Coordinates head and eye movement, eye
focus, helps for hearing

27. BRAIN: 3. Hindbrain
(задний мозг)
 Composed of medulla oblongata
(продолговатый мозг), cerebellum
(мозжечок) and pons (мост)

28. a. Medulla oblongata:
 Located in the border of spinal cord and brain
 Regulates respiratory, circulatory and excretory
activities, swallowing, sneezing, vomiting and etc.
b. Cerebellum:
 Located in posterior end of brain
 Regulates balance, posture and movement
c. Pons:
 Bridge-like structure
 Controls certain respiratory functions

30. CNS: spinal cord
 Spinal cord is a dense cable coming out from
brain and protected by vertebral column
 Spinal cord transmits signals from brain and
to brain and functions in reflexes
 A reflex is a sudden, involuntary contraction
of muscles in response to a stimulus.
 Spinal cord contains a core of grey matter
covered by white matter, grey matter
mainly neuron bodies and interneurons,
white matter axons

34. Peripheral nervous system
PNS
 PNS connects CNS to the rest of the body
 From brain 12 pair of nerves projected, from
spinal cord 31 pairs that go to all body parts
Body is controlled by 2 ways of PNS:
a. Somatic nervous system (soma means body)
b. Autonomic nervous system

36. 1. Somatic nervous system
 Most motor neurons that stimulate skeletal
muscles are UNDER OUR CONSCIOUS
CONTROL, like running, writing, swimming …
 They coordinate the voluntary action of our
body
 Some activity such as reflexes are involuntary,
because they are to protect our body and very
fast

37. 2. Autonomic nervous system
 Motor neurons that regulate smooth muscles
and NOT UNDER OUR CONSCIOUS CONTROL,
like heartbeat, peristalsis, blood vessels
contraction …
 They action involuntarily
 It is divided to PARASYMPATHETIC and
SYMPATHETIC nervous systems which maintain
stability in our body

38. 
The effects of parasympathetic and sympathetic nervous
system are opposite.

Generally sympathetic system helps the body deal with
emergency situations by accelerating some body activities.

Parasympathetic system promotes normal relaxed body
functioning.