Nervous system

1. The Nervous SystemThe Nervous System

2.  It includes Central NervousIt includes Central Nervous
System and the PeripheralSystem and the Peripheral
Nervous System.Nervous System.
 It acts as a highway forIt acts as a highway for
information to travel. It controlsinformation to travel. It controls
movement in the body and alsomovement in the body and also
converts information for the brainconverts information for the brain
to read and process.to read and process.
What is the Nervous SystemWhat is the Nervous System

3.  Two Anatomical DivisionsTwo Anatomical Divisions
 Central nervous system (CNS)Central nervous system (CNS)
 BrainBrain
 Spinal cordSpinal cord
 Peripheral nervous system (PNS)Peripheral nervous system (PNS)
 All the neural tissue outside CNSAll the neural tissue outside CNS
 AfferentAfferent division (sensory input)division (sensory input)
 EfferentEfferent division (motor output)division (motor output)
 Somatic nervous systemSomatic nervous system
 Autonomic nervous systemAutonomic nervous system
General Organization of the nervous system

4. NERVOUS SYSTEMNERVOUS SYSTEM

5. The Nervous system has three major functions:
 Sensory – monitors internal & external
environment through presence of receptors
 Integration – interpretation of sensory information
(information processing); complex (higher order)
functions
 Motor – response to information processed
through stimulation of effectors
 muscle contraction
 glandular secretion

6. Functions of the NervousFunctions of the Nervous
SystemSystem
1.1. Control center for all body activitiesControl center for all body activities
2.2. Responds and adapts to changes thatResponds and adapts to changes that
occur both inside and outside the bodyoccur both inside and outside the body
(Ex: pain, temperature, pregnancy)(Ex: pain, temperature, pregnancy)

7. Functions of the Nervous SystemFunctions of the Nervous System
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1. Sensory input – gathering information
•To monitor changes occurring inside and
outside the body (changes = stimuli)
2. Integration –
•to process and interpret sensory input
and decide if action is needed.
3. Motor output
•A response to integrated stimuli
•The response activates muscles or glands

8. General Organization of the nervous system
Brain & spinal
cord

9. Central Nervous System (CNS)Central Nervous System (CNS)
 Contains the nerves ofContains the nerves of
thethe brainbrain andand spinalspinal
cordcord
 Function =Function = coordinatingcoordinating
center ofcenter of
incoming/outgoingincoming/outgoing
informationinformation

10.  Brain is found in theBrain is found in the skullskull & serves as& serves as overall controloverall control
centercenter for the nervous systemfor the nervous system
 Spinal Cord is surrounded bySpinal Cord is surrounded by vertebraevertebrae and extendsand extends
down the back of the neck, thorax and abdomendown the back of the neck, thorax and abdomen
 Center ofCenter of many reflex actionsmany reflex actions
 Provides a linkProvides a link between sensory and motor nervesbetween sensory and motor nerves
 Both are enclosed in 3 protective membranes calledBoth are enclosed in 3 protective membranes called
thethe meningemeninge
 Space between meninge containsSpace between meninge contains cerebrospinalcerebrospinal
fluidfluid which protects and cushions the CNSwhich protects and cushions the CNS

12. Spinal VS Epidural

13. Central Nervous SystemCentral Nervous System
BrainBrain : a mass of 100: a mass of 100
billion neuronsbillion neurons
located inside thelocated inside the
skullskull
-Learning occurs as-Learning occurs as
more and strongermore and stronger
connections areconnections are
made betweenmade between
neuronsneurons

14. BrainBrain
 It is one of the largest organs in the body,It is one of the largest organs in the body,
and coordinates most body activities.and coordinates most body activities.
 It is the center for all thought, memory,It is the center for all thought, memory,
judgment, and emotion.judgment, and emotion.
 Each part of the brain is responsible forEach part of the brain is responsible for
controlling different body functions, suchcontrolling different body functions, such
as temperature regulation and breathing.as temperature regulation and breathing.

15. Anatomy of the BrainAnatomy of the Brain
CerebrumCerebrum : largest part: largest part
of human brainof human brain
- Responsible for:- Responsible for:
- Thought- Thought
- Language- Language
- Senses- Senses
- Memory- Memory
- Voluntary- Voluntary
movementmovement

16. CerebrumCerebrum
 It is the largest section of the brainIt is the largest section of the brain
 It is located in the upper portion of the brain andIt is located in the upper portion of the brain and
is the area that processes thoughts, judgment,is the area that processes thoughts, judgment,
memory, problem solving, and language.memory, problem solving, and language.
 The outer layer of the cerebrum is the cerebralThe outer layer of the cerebrum is the cerebral
cortex, which is composed of folds of graycortex, which is composed of folds of gray
matter.matter.
 The cerebrum is subdivided into the left and rightThe cerebrum is subdivided into the left and right
halves called cerebral hemispheres. Eachhalves called cerebral hemispheres. Each
hemisphere has 4 lobes.hemisphere has 4 lobes.

17. Anatomy of the BrainAnatomy of the Brain
CerebellumCerebellum : at base: at base
of brainof brain
-Responsible for:-Responsible for:
- Muscle- Muscle
coordinationcoordination
- Balance- Balance
- Posture- Posture

18. The CerebellumThe Cerebellum
 Second largest portion of the brainSecond largest portion of the brain
 Located beneath the posterior part of theLocated beneath the posterior part of the
cerebrumcerebrum
 Aids in coordinating voluntary bodyAids in coordinating voluntary body
movements and maintaining balance andmovements and maintaining balance and
equilibriumequilibrium
 Refines the muscular movement that isRefines the muscular movement that is
initiated in the cerebruminitiated in the cerebrum

19. Central Nervous SystemCentral Nervous System
 Brain (Cont.)Brain (Cont.)
 CerebellumCerebellum
 The Cerebellum is behind the brain stem. It is similar toThe Cerebellum is behind the brain stem. It is similar to
the Cerebral Cortex because it is divided intothe Cerebral Cortex because it is divided into
hemisphereshemispheres
 The Cerebellum controls movement, balance andThe Cerebellum controls movement, balance and
posture.posture.

20. Anatomy of the BrainAnatomy of the Brain
Brain StemBrain Stem : connects: connects
brain to spinal cordbrain to spinal cord
-Responsible for:-Responsible for:
- Breathing- Breathing
- Swallowing- Swallowing
- Heartbeat- Heartbeat
- Blood pressure- Blood pressure

21. Brain StemBrain Stem
 Midbrain—Midbrain—acts as a pathway for impulses toacts as a pathway for impulses to
be conducted between the brain and the spinalbe conducted between the brain and the spinal
cord.cord.
 PonsPons means bridge—connects the cerebellummeans bridge—connects the cerebellum
to the rest of the brain.to the rest of the brain.
 Medulla oblongata—Medulla oblongata— most inferior positionedmost inferior positioned
portion of the brain; it connects the brain to theportion of the brain; it connects the brain to the
spinal cord.spinal cord.

22. Central Nervous SystemCentral Nervous System
 Brain (Cont.)Brain (Cont.)
 Brain StemBrain Stem
 The brain stem is a name for the area of the brainThe brain stem is a name for the area of the brain
between the thalamus and spinal cord. The brain stembetween the thalamus and spinal cord. The brain stem
includes the medulla, pons and midbrain.includes the medulla, pons and midbrain.
 The Brain Stem controls most of the basic functions ofThe Brain Stem controls most of the basic functions of
life like breathing, heart rate and blood pressure.life like breathing, heart rate and blood pressure.
Midbrain
Pons
Medulla

23. PonsPons
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• The bulging center part of the brain
stem
• Mostly composed of fiber tracts
• Includes nuclei involved in the control of
breathing

24. Medulla OblongataMedulla Oblongata
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• The lowest part of the brain stem
• Merges into the spinal cord
• Includes important fiber tracts
• Contains important control centers
•Heart rate control
•Blood pressure regulation
•Breathing
•Swallowing
•Vomiting

25. Central Nervous SystemCentral Nervous System
 Brain (Cont.)Brain (Cont.)
 ThalamusThalamus
 The Thalamus is divided into two sides.The Thalamus is divided into two sides.
The Hypothalamus is positioned inThe Hypothalamus is positioned in
between the two sides.between the two sides.
 The Thalamus receives sensoryThe Thalamus receives sensory
information and movement information.information and movement information.
Thalamus

26. ThalamusThalamus
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• Surrounds the third ventricle
• The relay station for sensory impulses
• Transfers impulses to the correct part of
the cortex for localization and
interpretation

27. HypothalamusHypothalamus
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• Under the thalamus
• Important autonomic nervous system
center
•Helps regulate body temperature
•Controls water balance
•Regulates metabolism

28. HypothalamusHypothalamus
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• An important part of the limbic system
(emotions)
• The pituitary gland is attached to the
hypothalamus

29. Central Nervous SystemCentral Nervous System
 Brain (Cont.)Brain (Cont.)
 HypothalamusHypothalamus
 The hypothalamus is madeThe hypothalamus is made
of several areas of theof several areas of the
lower brain. It is only thelower brain. It is only the
size of a pea which is aboutsize of a pea which is about
1/300 of the entire brain.1/300 of the entire brain.
Hypothalamus

30. Central Nervous SystemCentral Nervous System
 Brain (Cont.)Brain (Cont.)
 HypothalamusHypothalamus
 The Hypothalamus controls bodyThe Hypothalamus controls body
temperature, emotions, hunger, thirst,temperature, emotions, hunger, thirst,
circadian rhythms. Despite its size,circadian rhythms. Despite its size,
the Hypothalamus controls some verythe Hypothalamus controls some very
important functions. One of the mostimportant functions. One of the most
important is the body temperatureimportant is the body temperature
control. It acts as a thermostat so itcontrol. It acts as a thermostat so it
senses the body changes and will tellsenses the body changes and will tell
different parts of the body to adjust.different parts of the body to adjust. Hypothalamus

31. EpithalamusEpithalamus
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• Forms the roof of the third ventricle
• Houses the pineal body (an endocrine
gland)
• Includes the choroid plexus – forms
cerebrospinal fluid

32. Central Nervous SystemCentral Nervous System
Spinal CordSpinal Cord : Column of nerves: Column of nerves
from brain to tailbone –from brain to tailbone –
protected by vertebrae ofprotected by vertebrae of
spinespine
- Responsible for:Responsible for:
- Conducting impulses- Conducting impulses
between the brain and thebetween the brain and the
rest of the bodyrest of the body
*Impulses may travel as fast at*Impulses may travel as fast at
268 miles/hr268 miles/hr

33. Central Nervous SystemCentral Nervous System
Spinal CordSpinal Cord
 StructureStructure
 There are 31 pairs of spinal nervesThere are 31 pairs of spinal nerves
which run through the spinal cord.which run through the spinal cord.
These nerves are called “mixed”These nerves are called “mixed”
nerves because each nerve containsnerves because each nerve contains
a sensory and a motor axon.a sensory and a motor axon.
 Information entering from the left sideInformation entering from the left side
of the spinal cord will eventually goof the spinal cord will eventually go
over to the right side of the brain andover to the right side of the brain and
vice versa. The side switching canvice versa. The side switching can
happen as soon as entering thehappen as soon as entering the
spinal cord or until it reaches thespinal cord or until it reaches the
brain.brain.
Spinal Cord
Sensory Neuron
Motor Neuron
Receptor
Effector

34. Central Nervous SystemCentral Nervous System
Spinal Cord (Cont.)Spinal Cord (Cont.)
 FunctionFunction
 The spinal cord is used for two main functions:The spinal cord is used for two main functions:
 It acts as a pathway for information to travel fromIt acts as a pathway for information to travel from
receptors (skin, eyes, mouth…) to the brain and from thereceptors (skin, eyes, mouth…) to the brain and from the
brain to effectors (muscle).brain to effectors (muscle).
 The spinal cord can also be a minor coordinating centreThe spinal cord can also be a minor coordinating centre
for some simple reflexes like the withdrawal reflex.for some simple reflexes like the withdrawal reflex.

35. Spinal CordSpinal Cord
 Protected by cerebrospinal fluid.Protected by cerebrospinal fluid.
 Inner core of the spinal cord contains grayInner core of the spinal cord contains gray
matter.matter.
 The outer portion of the spinal cord isThe outer portion of the spinal cord is
myelinated white matter.myelinated white matter.

36. Spinal CordSpinal Cord
 Runs through the vertebral canalRuns through the vertebral canal
 Extends from foramen magnum to 2Extends from foramen magnum to 2ndnd
lumbar vertebralumbar vertebra
 RegionsRegions
 CervicalCervical
 ThoracicThoracic
 LumbarLumbar
 SacralSacral
 CoccygealCoccygeal
 Gives rise to 31 pairs of spinal nerves - all are mixed nervesGives rise to 31 pairs of spinal nerves - all are mixed nerves

37. Protection of the Central NervousProtection of the Central Nervous
SystemSystem
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• Scalp and skin
• Skull and vertebral column
• Meninges
Figure 7.16a

38. Protection of the Central NervousProtection of the Central Nervous
SystemSystem
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• Cerebrospinal fluid
• Blood brain barrier
Figure 7.16a

39. MeningesMeninges
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• Dura mater
•Double-layered external covering
•Periosteum – attached to surface of the
skull
•Meningeal layer – outer covering of the
brain
•Folds inward in several areas

40. MeningesMeninges
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• Arachnoid layer
•Middle layer
•Web-like
• Pia mater
•Internal layer
•Clings to the surface of the brain

41. MeningesMeninges
 Dura mater:Dura mater: outermostoutermost
layer; continuous withlayer; continuous with
epineurium of the spinalepineurium of the spinal
nervesnerves
 Arachnoid mater:Arachnoid mater: thinthin
and wispyand wispy
 Pia mater:Pia mater: bound tightlybound tightly
to surfaceto surface

42. Cerebrospinal FluidCerebrospinal Fluid
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• Similar to blood plasma composition
• Formed by the choroid plexus
• Forms a watery cushion to protect the
brain
• Circulated in arachnoid space,
ventricles, and central canal of the
spinal cord

43. Ventricles and Location of theVentricles and Location of the
Cerebrospinal FluidCerebrospinal Fluid
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.17a

44. Ventricles and Location of theVentricles and Location of the
Cerebrospinal FluidCerebrospinal Fluid
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 7.17b

45. Blood Brain BarrierBlood Brain Barrier
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• Includes the least permeable capillaries
of the body
• Excludes many potentially harmful
substances
• Useless against some substances
•Fats and fat soluble molecules
•Respiratory gases
•Alcohol
•Nicotine
•Anesthesia

46. Peripheral Nervous SystemPeripheral Nervous System
 Includes both the 12 pairs of cranial nerves and the 31Includes both the 12 pairs of cranial nerves and the 31
pairs of spinal nerves.pairs of spinal nerves.
 A nerve is a group or bundle of axon fibers locatedA nerve is a group or bundle of axon fibers located
outside the central nervous system that carriesoutside the central nervous system that carries
messages between the CNS and the various parts ofmessages between the CNS and the various parts of
the body.the body.
 Whether a nerve is cranial or spinal is determined byWhether a nerve is cranial or spinal is determined by
where the nerve originates.where the nerve originates.
 Cranial nerves arise from the brain, mainly at theCranial nerves arise from the brain, mainly at the
medulla oblongata.medulla oblongata.

47. Autonomic Nervous SystemAutonomic Nervous System
 Involved with the control of involuntary orInvolved with the control of involuntary or
unconscious bodily functions.unconscious bodily functions.
 It is divided into two branches: sympatheticIt is divided into two branches: sympathetic
branchbranch and parasympathetic branch.and parasympathetic branch.
 The sympathetic nerves stimulate the body inThe sympathetic nerves stimulate the body in
times of stress and crisis.times of stress and crisis.
 The parasympathetic nerves serve as aThe parasympathetic nerves serve as a
counterbalance for the sympathetic nerves.counterbalance for the sympathetic nerves.

48. Somatic NervesSomatic Nerves
 Serve the skin and skeletal muscles.Serve the skin and skeletal muscles.
 These are also the nerves that carry motorThese are also the nerves that carry motor
commands to skeletal muscles.commands to skeletal muscles.
 Large variety of sensory receptors foundLarge variety of sensory receptors found
in the dermis layer of the skin use somaticin the dermis layer of the skin use somatic
nerves to send their information, such asnerves to send their information, such as
touch, temperature, pressure, and pain, totouch, temperature, pressure, and pain, to
the brain.the brain.

49. Peripheral Nervous System (PNS)Peripheral Nervous System (PNS)
 All parts of the nervous systemAll parts of the nervous system lying outsidelying outside
the brain and spinal cordthe brain and spinal cord..
 The sensory and motor neurons that connect toThe sensory and motor neurons that connect to
the CNSthe CNS
 Function =Function = to carry info between organs of the bodyto carry info between organs of the body
and the CNSand the CNS
 Humans haveHumans have
 12 paris of cranial nerves (sensory/motor/mixed)12 paris of cranial nerves (sensory/motor/mixed)
which control the head, face, neck, shoulderswhich control the head, face, neck, shoulders
 ExceptExcept VAGUS nerve – controls internal organsVAGUS nerve – controls internal organs
 31 pairs of spinal nerves (mixed) which take31 pairs of spinal nerves (mixed) which take
impulses to and from the spinal cordimpulses to and from the spinal cord

50. PNSPNS
Somatic & Autonomic NervesSomatic & Autonomic Nerves
 Somatic nervesSomatic nerves control skeletal muscle, bones,control skeletal muscle, bones,
skin that a person can controlskin that a person can control
 Sensory neuronsSensory neurons which relay info aboutwhich relay info about
environment to CNSenvironment to CNS
 Motor neuronsMotor neurons which initiate appropriate responsewhich initiate appropriate response
 Autonomic nervesAutonomic nerves control the muscles of thecontrol the muscles of the
glands and internal organs which we can’tglands and internal organs which we can’t
controlcontrol
 SympatheticSympathetic && parasympatheticparasympathetic componentscomponents
Reflex Arc

51. SympatheticSympathetic component prepares body for stresscomponent prepares body for stress
[neurotransmitter used=[neurotransmitter used=norepinephrine]norepinephrine]
 Diverts blood from internal organs toDiverts blood from internal organs to skeletalskeletal
muscles, heart & brainmuscles, heart & brain
ParasympatheticParasympathetic brings things back to normalbrings things back to normal
[neurotransmitter used=[neurotransmitter used=acetylcholineacetylcholine]]
 Work in conjunction/opposition to each otherWork in conjunction/opposition to each other
 Ex. “on” / “off” switchesEx. “on” / “off” switches
“FLIGHT OR FIGHT RESPONSE”

54. Peripheral Nervous SystemPeripheral Nervous System
 Sensory NeuronsSensory Neurons
 Sensory Neurons are neurons which onlySensory Neurons are neurons which only
allow information to travel one way. They canallow information to travel one way. They can
transmit information from Receptors (skin,transmit information from Receptors (skin,
eyes, ears) to the brain and to motor neurons.eyes, ears) to the brain and to motor neurons.

55. Peripheral Nervous SystemPeripheral Nervous System
 Motor NeuronsMotor Neurons
 Motor Neurons are neurons which only allowMotor Neurons are neurons which only allow
information to travel one way. The transmitinformation to travel one way. The transmit
information from the brain and the spinal cordinformation from the brain and the spinal cord
to the Effectors (Muscles and Glands)to the Effectors (Muscles and Glands)

56. Peripheral Nervous SystemPeripheral Nervous System
 Example of a Reflex ArcExample of a Reflex Arc
 A reflex arc is the pathway that a nerve reflex, such as theA reflex arc is the pathway that a nerve reflex, such as the
knee jerk reflex, follows.knee jerk reflex, follows.
1.1. A tap on the knee stimulates sensory receptors (tendon),A tap on the knee stimulates sensory receptors (tendon),
generating a nerve signal.generating a nerve signal.
2.2. The signal travels along a nerve to the spinal cord.The signal travels along a nerve to the spinal cord.
3.3. In the spinal cord, the signal is transmitted from the sensoryIn the spinal cord, the signal is transmitted from the sensory
nerve to a motor nerve.nerve to a motor nerve.
4.4. The motor nerve sends the signal back to effectors (muscle)The motor nerve sends the signal back to effectors (muscle)
in the thigh.in the thigh.
5.5. The muscle contracts, causing the lower leg to jerk upward.The muscle contracts, causing the lower leg to jerk upward.
The entire reflex occurs without involving the brain.The entire reflex occurs without involving the brain.

57. Peripheral Nervous SystemPeripheral Nervous System
NervesNerves : visible: visible
bundles of axons andbundles of axons and
dendrites that entenddendrites that entend
from the brain andfrom the brain and
spinal cord to all otherspinal cord to all other
parts of the bodyparts of the body

58. -Responsibilities:-Responsibilities:
-- Sensory nervesSensory nerves --
carry messagescarry messages
from body to brainfrom body to brain
(pain, pressure,(pain, pressure,
temperature)temperature)
-- Motor nervesMotor nerves ––
carry messagescarry messages
from brain to body tofrom brain to body to
respondrespond

59. Functional Classification of theFunctional Classification of the
Peripheral Nervous SystemPeripheral Nervous System
Slide 7.3aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Sensory (afferent) division
•Nerve fibers that carry information to the
central nervous system
Figure 7.1

60. Functional Classification of theFunctional Classification of the
Peripheral Nervous SystemPeripheral Nervous System
Slide 7.3bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Motor (efferent) division
•Nerve fibers that carry impulses away from
the central nervous system
Figure 7.1

61. Functional Classification of theFunctional Classification of the
Peripheral Nervous SystemPeripheral Nervous System
Slide 7.3cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Motor (efferent) division
•Two subdivisions
• Somatic nervous system = voluntary
• Autonomic nervous system = involuntary
Figure 7.1

62. Classification of NervesClassification of Nerves
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• Mixed nerves – both sensory and motor
fibers
• Afferent (sensory) nerves – carry
impulses toward the CNS
• Efferent (motor) nerves – carry impulses
away from the CNS

63. Autonomic FunctioningAutonomic Functioning
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• Sympathetic – “fight-or-flight”
•Response to unusual stimulus
•Takes over to increase activities
•Remember as the “E” division = exercise,
excitement, emergency, and
embarrassment

64. Autonomic FunctioningAutonomic Functioning
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• Parasympathetic – housekeeping
activites
•Conserves energy
•Maintains daily necessary body functions
•Remember as the “D” division - digestion,
defecation, and diuresis