control system in humans, neurons, types of neurons, nerves, human nervous system, CNS, PNS, ANS, Brain, parts of brain, spinal cord, functions of spinal cord, reflex arc, PNS, ANS,

1. Control and
Coordination

2. Some important terms
 Stimulus- any external or internal factor that
causes a living organism to react is called a
stimulus. (Pl: stimuli)
 Response- the specific reaction shown by a living
organism towards a stimulus
 Impulse- a electrical wave of excitation or
irritation that travels across a neuron and carries
specific messages.

3. Some important terms
Receptors- group of organs
that receive sensory
impulses and convey them
to the brain
Effectors- group of organs
that show responses to a
specific stimulus

4. Neuron-
 The fundamental structural and functional unit of
the nervous system that carries impulses across
the body.

5. Structure of a neuron
A neuron is made up of two main parts;
a) Cyton
b) Axon
Cyton – also called cell body, this part of neuron
contains a large prominent nucleus in the center.
The cell membrane is branched into several
cytoplasmic
branches called dendrites.
Dendrites receive the impulses.

6. Structure of a neuron
The cytoplasm is called neuroplasm.
Inside the neuroplasm are scattered several stainable
granules called Nissl granules.
B) Axon – The long cytoplasmic projection of the
neuron that extends from the cell body.
An axon is covered by an insulating membrane
called
Neurolemna.
Axons carry the impulse they receive from the cyton.
They usually terminate into another neuron or an
organ or gland or muscle.

7. Structure of a neuron
In some neuron there is an additional envelop inside
the
neurolemna called the Myelin sheath which help in
faster conduction of the impulse.
Such neurons are called myelinated neurons and
are
mostly present in cerebral medulla.
Impulse always travels from Cyton to Axon.

8. Types of Neurons
 Sensory neurons- Those neurons that carry
impulses from the receptors (sense organs)to the
brain. These impulses are sensory in nature.
 Motor neurons- Those neurons that carry impulses
from the brain to the effectors . These impulses
are motor in nature.
 Associated neurons- They are also called mixed
neurons as they carry impulses both to and from
the brain.

9. Types of Neurons
Sensory
Motor
Interneuron

10. Nerves
A bundle of neurons with a common envelop
around the
axons called nerve membrane.
A nerve provides a common
pathway for the
electrochemical
nerve impulses that are
transmitted along each of the
axons

11. Types of Nerves
 Sensory nerves- Those nerves that carry impulses
from the receptors (sense organs)to the brain.
These impulses are sensory in nature.
 Motor nerves- Those nerves that carry impulses
from the brain to the effectors . These impulses
are motor in nature.
 Mixed nerves- They are also called mixed nerves
as they carry impulses both to and from the brain.
They are also called spinal nerves.

12. Human
Nervous
System

13. Classification of the
Human Nervous System
The human Nervous System is classified into three
major divisions-
The Central Nervous System
The Peripheral Nervous System
The Autonomous Nervous System

14. Central Nervous System
 The CNS constitutes the main division of the
Nervous system in Human Beings.
 It comprises of two main organs concerned with
control and coordination-
A) The Brain
B) The Spinal Cord.

15. The Brain

16. The Brain
 Location: Head region
 Protection: a) Body protection made up of
immobile bones that make up the skull. The skull is
also called the Cranium.
b) Membranous protection in the form of three
membranes called the meninges. These three
layers are called – Dura mater, Arachnoid mater
and Pia mater.
The cerebro-spinal fluid in between the three
layers, protects the brain further from

17. The BrainThe Brain
 weighs 1300 - 1400 g
 made up of about 100
billion neurons
 “the most complex living
structure on the universe”
Society for Neuroscience
 makes us who we are

18. The BrainThe Brain
Phineas gage

19. Brain structureBrain structure
Cerebrum
cerebellum
hypothalamus
Pituitary gland
medulla
brain functions

20. Parts of the cerebrumParts of the cerebrum
memory game

21. Parts of the cerebrumParts of the cerebrum
alcohol and the brain

23. Meninges of the Brain

24. Dura mater
 Dura mater or dura, is a thick membrane that is the
outermost of the three layers of the meninges that surround
the brain and spinal cord. It is derived from mesoderm.
 The dura mater has several functions and layers. The dura
mater is a sac (aka thecal sac) that envelops the arachnoid
mater. It surrounds and supports the dural sinuses (also called
dural venous sinuses, cerebral sinuses, or cranial sinuses) and
carries blood from the brain toward the heart.
 The dura mater has two layers, or lamellae: The superficial
layer (also called the periosteal layer), which serves as the
skull's inner periosteum, called the endocranium; and a deep
layer called the meningeal layer; the actual dura mater

25. Arachnoid mater
 The middle element of the meninges is the arachnoid mater, so
named because of its spider web-like appearance. It cushions
the central nervous system. This thin, transparent membrane is
composed of fibrous tissue and, like the pia mater, is covered by
flat cells also thought to be impermeable to fluid.
 The shape of the arachnoid does not follow the convolutions of
the surface of the brain and so looks like a loosely fitting sac. In
particular, in the region of the brain a large number of fine
filaments called arachnoid trabeculae pass from the arachnoid
through the subarachnoid space to blend with the tissue of the pia
mater. The arachnoid is composed of an outermost portion
(arachnoid barrier cell layer) with tightly packed cells and no
extracellular collagen; that is why it is considered to represent an
effective morphological and physiological meningeal barrier
between the cerebrospinal fluid and subarachnoid space and the
blood circulation in the dura.

26. Pia mater
 The pia mater (Latin: tender mother) is a very
delicate membrane. It is the meningeal envelope
that firmly adheres to the surface of
the brain and spinal cord, following all of the
brain's contours (the gyri and sulci). It is a very thin
membrane composed of fibrous tissue covered
on its outer surface by a sheet of flat cells thought
to be impermeable to fluid. The pia mater is
pierced by blood vessels to the brain and spinal
cord, and its capillaries nourish the brain.

27. Parts of the Brain
Fore- Brain
The fore brain makes up the largest part of the brain.
The forebrain consists of
the cerebrum,
thalamus,
and hypothalamus (part of the limbic system)

28. Fore Brain
 Olfactory lobes:
Two small lobe like
structures situated in
the lower part of the
anterior brain.
Controls the sense of
smell

29. Fore Brain
The cerebrum is the largest, most prominent part
of the human brain. The longitudinal fissure
partitions the cerebrum into right and left
hemispheres, which are each separated into
four lobes:
 Frontal
 Parietal
 Temporal
 Occipital
 The cerebrum consists of the cerebral cortex
(outer gray matter) and white matter.
 The cerebral cortex is configured into
convolutions (folds) that maximize surface area
 The interior white matter consists of myelinated
axons of neurons that link several regions of the
brain

30. Lobes of the Cerebrum
 Frontal Lobe- associated
with reasoning, planning,
parts of speech, movement,
emotions, and problem
solving
 Parietal Lobe- associated
with movement, orientation,
recognition, perception of
stimuli
 Occipital Lobe- associated
with visual processing
 Temporal Lobe- associated
with perception and
recognition of auditory
stimuli, memory, and
speech

31. Fore Brain
Thalamus is between the
cerebral cortex and the midbrain,
both in terms of its location and
its neurological connections. Its
function includes relaying
sensation and special sense
signals to the cerebral cortex,
relaying motor signals from the
cerebral cortex, and the
regulation of consciousness, sleep
and alertness.

32. Fore Brain
Hypothalamus
The hypothalamus is a portion of the brain that
contains a number of small nuclei with a variety of
functions. One of the most important functions of
the hypothalamus is to link the nervous system to
the endocrine system via the pituitary gland
(hypophysis). The hypothalamus, is located below
the thalamus, just above the brain stem
The hypothalamus is responsible for certain
metabolic processes and other activities of the
Autonomic Nervous System. It synthesizes and
secretes neurohormones

33. Mid Brain
 It consist of Crura
cerebri and corpora
Quadregemina.

34. Hind Brain
 Hind brain is
made up of
three parts:
a) Cerebellum
b) Pons
c) Medulla
oblongata

35. Cerebellum
 The hind part of brain. It is divided into cerebellar
cortex and cerebellar medulla.
 Cerebellar cortex has longitudinal fissures and not
folds. While the medulla looks like a branched
tree.
 Cerebellum consists of 12% of the brain.
Functions:
a) It controls muscular co-ordination
b) It regulates body balance.

36. Medulla Oblongata
 The medulla contains
the cardiac,
respiratory, vomiting
and vasomotor
centers and deals
with autonomic
functions, such as
breathing, heart rate
and blood pressure

37. Pons Verolli
 The pons is a structure
located on the brain stem.
 The pons relays sensory
information between the
cerebellum and cerebrum,
aids in relaying other
messages in the brain,
controls arousal, and
regulates respiration.

38. Spinal
Cord

39. Spinal Cord- Structure
 The spinal cord is an extension
of the brain stem.
 It runs mid-dorsally through the
body and innervates the
body.
 The Sectional view of the
spinal cord shows the outer
white matter and inner grey
matter.
 The inter-neurons are present
in the gray matter and help in
reflexes.
 Spinal cord is protected by a
set of 33 bones called
vertebral column and the
three meninges.

40. Spinal Cord- Structure
 A central canal is filled with the
cerebro-spinal fluid.
 31 pairs of spinal nerves emerge
out from either sides of the spinal
cord.
 Spinal nerves are mixed nerves as
they have the sensory as well as
the motor neurons in them.

41. Functions of the spinal
cord
Spinal cord conducts
impulses from the
receptors to the brain as
well as from the brain to
the effectors.
Spinal cord controls
reflexes.

42. Reflexes
 A reflex is an involuntary, rapid response towards
a stimulus with the active participation of the
brain. Reflexes are protective responses against
harmful stimuli.
For ex: If we touch a hot plate we recoil our hand
immediately to prevent it from getting burnt. This
immediate and unconscious response is called
reflex
 Reflexes can be inborn or acquired.

43. Reflex Arc
 The path travelled by an
impulse during a reflex
response is called a reflex
arc.
 A reflex arc begins from
the receptors passes
through the sensory
neuron, passes via the
interneuron to the motor
neuron and then to the
effectors.

44. Peripheral
Nervous
System

45. PNS
 The peripheral nervous system is composed of
sensory neurons and the neurons that connect
them to the nerve cord, spinal cord and brain,
which make up the central nervous system. In
response to stimuli, sensory neurons generate and
propagate signals to the central nervous system
which then processes and conducts signals back
to the muscles and glands.
 It is made up of 12 Pairs of Cranial Nerves and 31
pairs of spinal nerves.

46. Autonomic
Nervous System

47. ANS
 The autonomic nervous system (ANS or visceral
nervous system) is the part of the
peripheral nervous system that acts as a
control system functioning largely below the level
of consciousness, and controls visceral functions.
The ANS affects heart rate, digestion, respiration
rate, salivation, perspiration, diameter of the
pupils, micturition (urination), and sexual arousal.
Whereas most of its actions are involuntary, some,
such as breathing, work in tandem with the
conscious mind.

48. Divisions of the ANS
IT IS CLASSICALLY DIVIDED INTO TWO SUBSYSTEMS: THE
PARASYMPATHETIC NERVOUS SYSTEM AND
SYMPATHETIC NERVOUS SYSTEM

49. Sympathetic Nervous System
Promotes a "fight or flight" response,
corresponds with arousal and energy
generation, and inhibits digestion.
Diverts blood flow away from the
gastro-intestinal (GI) tract and skin via
vasoconstriction.
Blood flow to skeletal muscles and the
lungs is not only maintained, but
enhanced (by as much as 1200% in the
case of skeletal muscles).

50. Sympathetic Nervous System
 Dilates bronchioles of the lung, which
allows for greater alveolar oxygen
exchange.
 Increases heart rate and the contractility
of cardiac cells (myocytes), thereby
providing a mechanism for the
enhanced blood flow to skeletal muscles.
 Dilates pupils and relaxes the lens,
allowing more light to enter the eye.
 Inhibits peristalsis.

51. Parasympathetic Nervous System
Promotes a "rest and digest" response,
promotes calming of the nerves return to
regular function, and enhances digestion.
Dilates blood vessels leading to the GI tract,
increasing blood flow. This is important
following the consumption of food, due to the
greater metabolic demands placed on the
body by the gut.
The parasympathetic nervous system can also
constrict the bronchiolar diameter when the
need for oxygen has diminished.

52. Parasympathetic Nervous System
Normalizes Heart Beat levels.
During accommodation, the
parasympathetic nervous system causes
constriction of the pupil and lens.
The parasympathetic nervous system
stimulates salivary gland secretion, and
accelerates peristalsis, so, in keeping with
the rest and digest functions, appropriate
PNS activity mediates digestion of food
and indirectly, the absorption of nutrients.
Is also involved in erection of genitals