The Nervous System
THE NERVOUS SYSTEM.................................................................................................................................. 1
OVERVIEW.................................................................................................................................................... 3
DEVELOPMENT OF THE NERVOUS SYSTEM..................................................................................................................3
Neurulation:....................................................................................................................................................4
Neurogenesis:.................................................................................................................................................4
Neural development: Adult derivatives..........................................................................................................4
REGIONS OF THE BRAIN AND THEIR FUNCTION.............................................................................................................5
FUNCTIONAL HISTOLOGY OF CNS & PNS........................................................................................................ 5
CELLULAR ORGANISATION OF NERVOUS SYSTEM.........................................................................................................5
CNS: GENERAL ORGANISATION/ HISTOLOGY..............................................................................................................6
The cortical layers of the Brain:......................................................................................................................6
Modular Organization of Cortical Layers of the Brain:..................................................................................7
Cerebellum (“Little Brain”):.............................................................................................................................7
The Subcortical Grey Matter:..........................................................................................................................7
THE SPINAL CORD:................................................................................................................................................ 7
Cells in the CNS:..............................................................................................................................................7
CYTOLOGY OF NERVOUS SYSTEM.................................................................................................................. 8
CLASSIFICATION OF NEURONS:.................................................................................................................................8
COMMON TYPES OF NEURONS:................................................................................................................................8
INTRACELLULAR STRUCTURE OF A NEURON:................................................................................................................9
AXONAL TRANSPORT:.............................................................................................................................................9
GLIAL (SUPPORT) CELLS IN THE CNS:.......................................................................................................................10
Oligodendrocytes:.........................................................................................................................................10
DIFFERENCE BETWEEN MYELINATION IN THE CNS AND THE PNS:.................................................................................10
Astrocytes:....................................................................................................................................................10
Microglia:......................................................................................................................................................11
Ependymal glia:............................................................................................................................................11
GANGLIA (PNS)..................................................................................................................................................11
STRUCTURE OF A PERIPHERAL NERVE.......................................................................................................................11
PNS MYELINATION..............................................................................................................................................12
Structural components of PNS Myelin..........................................................................................................12
Formation of Myelin:....................................................................................................................................12
Nerve fibre types and Myelination:..............................................................................................................12
PROTECTION OF THE CNS............................................................................................................................ 12
BLOOD-BRAIN BARRIER........................................................................................................................................12
Layers of structural protection:....................................................................................................................12
Structure of blood capillaries in the brain:...................................................................................................13
Meningeal Barriers:......................................................................................................................................13
Blood-Brain Barrier and Disease..................................................................................................................13
CSF.................................................................................................................................................................. 13
FUNCTIONAL AND ANATOMICAL SUBDIVISIONS OF THE NERVOUS SYSTEM.................................................14
NERVOUS SYSTEM CLASSIFICATION.........................................................................................................................14
CENTRAL NERVOUS SYSTEM..................................................................................................................................14
The Forebrain: Cerebrum..............................................................................................................................14
The Forebrain: basal ganglia........................................................................................................................15
The Forebrain: Limbic System.......................................................................................................................15
The Forebrain: Hypothalamus......................................................................................................................16
Cerebellum structure & function:.................................................................................................................16
Brain stem.....................................................................................................................................................16
Sensory and Motor Cortical Areas................................................................................................................17
PRINCIPLE OF SOMATOTOPY:.................................................................................................................................17
, The Nervous System
THE PERIPHERAL NERVOUS SYSTEM........................................................................................................................17
Autonomous Nervous System:......................................................................................................................18
RECEPTORS................................................................................................................................................. 18
CLASSIFICATIONS................................................................................................................................................. 18
SENSORY-MOTOR SYSTEMS...................................................................................................................................19
OVERVIEW OF THE MOTOR SYSTEM........................................................................................................................19
A REFLEX ARC:................................................................................................................................................... 20
Mechanisms:.................................................................................................................................................20
RECEPTORS IN THE SKIN (CUTANEOUS SENSATION).....................................................................................................20
MUSCLE PROPRIOCEPTION....................................................................................................................................21
The Motor Unit:............................................................................................................................................21
COMMON CNS NEUROTRANSMITTERS....................................................................................................................21
ELECTRICAL SIGNALS IN A MONOSYNAPTIC REFLEX ARC...............................................................................................21
CHARACTERISATION OF STIMULI.............................................................................................................................22
Two-Point Discrimination:............................................................................................................................23
Common Plan of Sensory Systems:...............................................................................................................23
TEMPERATURE SENSITIVE RECEPTORS.......................................................................................................................23
PRACTICAL.................................................................................................................................................. 23
, The Nervous System
Overview
CNS: Brain, Retina/Optic Nerve, Spinal Cord
PNS: Cranial nerves, spinal nerves
- Afferent = incoming
- Efferent = outgoing
- Connects to the CNS
- ‘horses tail’ = nerves at bottom of spine that are pulled down rather than sideways
as person grows
- Subdivisions of PNS:
o Somatic Nervous system – Conscious control
o Autonomous – Involuntary control
Innervates visceral organs
Parasympathetic = Rest & Digestion
Sympathetic = Fight or Flight
Nervous tissues are organised in a unique and region-specific manner
- Grey matter in cortical layers around the outside of the brain
- White matter on the inside of the brain
Development of the
Nervous System
- Complexity increases as we go up in the
evolutionary tree
o HOWEVER, more primitive does
not mean inferior. Giant squids
have largest eyes
- Ganglia = aggregation of nerve cells that
forms a functional unit
- Primitive nerve ladder seen in Planarian
(flatworms)
- Segmental Ganglion in Annelids
- Primitive brain in arthropods
- Molluscs have highly developed brain,
ganglia and transverse nerves.
o Giant squids have largest eyes (can be size of a plate)
- Chordata have nervous system quite similar to ours
- Common motifs:
o Cerebrum becomes increasingly larger as you go up the evolutionary phylogenetic tree
– becomes very very large in mammals, with many folds
o Cerebellum particularly large in mammals, birds and bony fishes who have quick
sophisticated movement– correlation between functionality of this portion of the brain
to its size
Sophisticated movement/motor control required, so very sophisticated
cerebellum
THE NERVOUS SYSTEM.................................................................................................................................. 1
OVERVIEW.................................................................................................................................................... 3
DEVELOPMENT OF THE NERVOUS SYSTEM..................................................................................................................3
Neurulation:....................................................................................................................................................4
Neurogenesis:.................................................................................................................................................4
Neural development: Adult derivatives..........................................................................................................4
REGIONS OF THE BRAIN AND THEIR FUNCTION.............................................................................................................5
FUNCTIONAL HISTOLOGY OF CNS & PNS........................................................................................................ 5
CELLULAR ORGANISATION OF NERVOUS SYSTEM.........................................................................................................5
CNS: GENERAL ORGANISATION/ HISTOLOGY..............................................................................................................6
The cortical layers of the Brain:......................................................................................................................6
Modular Organization of Cortical Layers of the Brain:..................................................................................7
Cerebellum (“Little Brain”):.............................................................................................................................7
The Subcortical Grey Matter:..........................................................................................................................7
THE SPINAL CORD:................................................................................................................................................ 7
Cells in the CNS:..............................................................................................................................................7
CYTOLOGY OF NERVOUS SYSTEM.................................................................................................................. 8
CLASSIFICATION OF NEURONS:.................................................................................................................................8
COMMON TYPES OF NEURONS:................................................................................................................................8
INTRACELLULAR STRUCTURE OF A NEURON:................................................................................................................9
AXONAL TRANSPORT:.............................................................................................................................................9
GLIAL (SUPPORT) CELLS IN THE CNS:.......................................................................................................................10
Oligodendrocytes:.........................................................................................................................................10
DIFFERENCE BETWEEN MYELINATION IN THE CNS AND THE PNS:.................................................................................10
Astrocytes:....................................................................................................................................................10
Microglia:......................................................................................................................................................11
Ependymal glia:............................................................................................................................................11
GANGLIA (PNS)..................................................................................................................................................11
STRUCTURE OF A PERIPHERAL NERVE.......................................................................................................................11
PNS MYELINATION..............................................................................................................................................12
Structural components of PNS Myelin..........................................................................................................12
Formation of Myelin:....................................................................................................................................12
Nerve fibre types and Myelination:..............................................................................................................12
PROTECTION OF THE CNS............................................................................................................................ 12
BLOOD-BRAIN BARRIER........................................................................................................................................12
Layers of structural protection:....................................................................................................................12
Structure of blood capillaries in the brain:...................................................................................................13
Meningeal Barriers:......................................................................................................................................13
Blood-Brain Barrier and Disease..................................................................................................................13
CSF.................................................................................................................................................................. 13
FUNCTIONAL AND ANATOMICAL SUBDIVISIONS OF THE NERVOUS SYSTEM.................................................14
NERVOUS SYSTEM CLASSIFICATION.........................................................................................................................14
CENTRAL NERVOUS SYSTEM..................................................................................................................................14
The Forebrain: Cerebrum..............................................................................................................................14
The Forebrain: basal ganglia........................................................................................................................15
The Forebrain: Limbic System.......................................................................................................................15
The Forebrain: Hypothalamus......................................................................................................................16
Cerebellum structure & function:.................................................................................................................16
Brain stem.....................................................................................................................................................16
Sensory and Motor Cortical Areas................................................................................................................17
PRINCIPLE OF SOMATOTOPY:.................................................................................................................................17
, The Nervous System
THE PERIPHERAL NERVOUS SYSTEM........................................................................................................................17
Autonomous Nervous System:......................................................................................................................18
RECEPTORS................................................................................................................................................. 18
CLASSIFICATIONS................................................................................................................................................. 18
SENSORY-MOTOR SYSTEMS...................................................................................................................................19
OVERVIEW OF THE MOTOR SYSTEM........................................................................................................................19
A REFLEX ARC:................................................................................................................................................... 20
Mechanisms:.................................................................................................................................................20
RECEPTORS IN THE SKIN (CUTANEOUS SENSATION).....................................................................................................20
MUSCLE PROPRIOCEPTION....................................................................................................................................21
The Motor Unit:............................................................................................................................................21
COMMON CNS NEUROTRANSMITTERS....................................................................................................................21
ELECTRICAL SIGNALS IN A MONOSYNAPTIC REFLEX ARC...............................................................................................21
CHARACTERISATION OF STIMULI.............................................................................................................................22
Two-Point Discrimination:............................................................................................................................23
Common Plan of Sensory Systems:...............................................................................................................23
TEMPERATURE SENSITIVE RECEPTORS.......................................................................................................................23
PRACTICAL.................................................................................................................................................. 23
, The Nervous System
Overview
CNS: Brain, Retina/Optic Nerve, Spinal Cord
PNS: Cranial nerves, spinal nerves
- Afferent = incoming
- Efferent = outgoing
- Connects to the CNS
- ‘horses tail’ = nerves at bottom of spine that are pulled down rather than sideways
as person grows
- Subdivisions of PNS:
o Somatic Nervous system – Conscious control
o Autonomous – Involuntary control
Innervates visceral organs
Parasympathetic = Rest & Digestion
Sympathetic = Fight or Flight
Nervous tissues are organised in a unique and region-specific manner
- Grey matter in cortical layers around the outside of the brain
- White matter on the inside of the brain
Development of the
Nervous System
- Complexity increases as we go up in the
evolutionary tree
o HOWEVER, more primitive does
not mean inferior. Giant squids
have largest eyes
- Ganglia = aggregation of nerve cells that
forms a functional unit
- Primitive nerve ladder seen in Planarian
(flatworms)
- Segmental Ganglion in Annelids
- Primitive brain in arthropods
- Molluscs have highly developed brain,
ganglia and transverse nerves.
o Giant squids have largest eyes (can be size of a plate)
- Chordata have nervous system quite similar to ours
- Common motifs:
o Cerebrum becomes increasingly larger as you go up the evolutionary phylogenetic tree
– becomes very very large in mammals, with many folds
o Cerebellum particularly large in mammals, birds and bony fishes who have quick
sophisticated movement– correlation between functionality of this portion of the brain
to its size
Sophisticated movement/motor control required, so very sophisticated
cerebellum
