Nervous system (p115 onwards)
Sensory – Detects changes in environment, located throughout the body
- Receptors capable of detecting both external and internal changes.
Integration – Nervous system processes sensory input and decides if a response is required
Motor Output – Nervous system sends down motor message to respond to stimulus (Only if integration
decides a response is needed)
Central Nervous System (CNS): Consist of
brain and spinal cord, encased in bone as a
form of protection of delicate organ system.
- Functionally grouped into: sensory,
motor, and connector/interneurons
Peripheral Nervous system (PNS): Located
outside of CNS – Functional division as
a. Sensory (Afferent): Responsible for
receiving information from receptors
and transmitting to the CNS
Split into two groups:
Sensory somatic (Body): eg. Touch, pain and pressure
Visceral (Organs): Blood vessels, digestive organs, respiratory organs
- Most of the time does not reach conscious levels, unless sensation is extreme (eg. Stomach
b. Motor (Efferent): Responsible for transmitting motor impulses from CNS to muscles/glands.
Somatic (Body): eg. Conscious contraction of striated/skeletal muscles
Visceral (Organs): unconscious (autonomic) contraction of smooth muscle, cardiac
i. Sympathetic ii. Parasympathetic Functional Unit
Neuron: Functional unit of nervous system (carries out function by receiving electrical stimulus and
Cell body – contains the cell body, nucleus
Dendrite(s) – extension of cytoplasm that
are responsible directing information
towards the cell body.
Axon – extension of cytoplasm for directing
information away from cell body Non-Nervous Cells: Neuroglial Cells in the CNS
Astrocytes –cell processes sticking out – acts as blood-brain barrier
- Positioned in between blood vessels (capillaries) and neurons. They regulate what substances
come in contact with neurons.
- Also provides structural integrity.
Oligodendrocytes – Smooth, bullous shape.
- Extension wrap around axons to produce myelin sheath (Myelin is fatty coating around axons
- Myelin appears lighter in colour therefore axons that are myelinated are said to be white matter
of the CNS.
Microglial Cells – Mimics bodies lymphatic system, cell that destroys pathogens.
Ependymal Cells – Simple cuboidal epithelial cells with specialized cilia
– Living in the cavity of spinal cord
- Cilia secrete to make Cerebral spinal Fluid (CSF)
Non-Nervous Cells – Peripheral Nervous System
Satellite Cells – Cover the cell body in the ganglia.
- Important for regulation of exchange of nutrients and waste between neurons an ext.
Schawnn (Neurolemmocytes) cells – Forming myelin sheath around axons in the PNS The Brain – Fore, Mid and Hind Regions
Forebrain: Cerebrum, Thalamus, Hypothalamus, Basal Ganglia
Cerebrum – Divided into two hemispheres, most of forebrain.
- Outer covering is called the cortex, consist of non-myelinated cell bodies (Gray Matter)
- Convoluted/folded – grooves are Sulci and the hills between grooves are called Gyri
- Longitudinal Fissure, (sulci groove) that separates the cerebral hemisphere
- Central Sulcus – separates the Frontal lobe from Parietal Lobe
- Lateral Sulcus – superior border for Temporal Lobe
- Parieto-occiptal Sulcus – separates Parietal Lobe and Occipital Lobe
- Insula lobe is located deep to the Temporal Lobe
- Gyrus infront of Central Sulcus is called Pre-Central Gyrus – responsible for Motor Function
- Behind is termed Post-Central Gyrus – responsible for Sensory Information.
White Matter – Beneath the Gray matter of the cortex are myelinated axons of neurons. Axons that joni
gyri in the same hemispheres are called Association type tracts. - Commissural tracts – myelinated axons that join the right to left hemispheres. An example of
the largest is termed the Corpus Callosum
- Projection tracts/fibres – myelinated axons that transmit sensory info up the cortex –or- that
transmits motor information down through the cerebrum.
Gray Matter - All outside consists of non-myelinated axons (lots of cell bodies). Floor of forebrain nuclei
of neurons group together to form distinct structures:
1. Thalamus – relay centre for almost all sensory information that goes through cerebral cortex
2. Hypothalamus – Controller for the Autonomic Nervous System and Endocrine System 3. Basal Ganglia – Grouping of cerebral nuclei receive information from cerebral cortext to
regulate skeletal movement
Midbrain – In between the forebrain and hindbrain.
Functions: Nuclei of the two cranial nerves control the movement of the eyes
- Superior Cerebellar Peduncles are motor tracts that run back to the cerebellum
- Visual and Auditory reflex centres Hindbrain – consists of two parts, the Pons and the Medulla Oblongata.
Pons – Regulates breathing: rate and depth.
- Contains the nuclei of cranial nerves 5-8 (5,6,7,8)
- Peduncles comes off the pons and travels back to the cerebellum (Mid Cerebellar Peduncles)
Medulla Oblongata – Reflex centres that regulate vital functions (HR, Breathing rate, BP)
- Contains cranial nerves 8-12
- Inferior Cerebellar Peduncles connects to the cerebellum
Cerebellum – similar to the cerebrum that is outer layer is cortex and convoluted (gyri and sulci).
Responsible for coordination of motor movement
- Two hemisphere separated by a narrow midline called Vermis
- Arbor Vitae (tree) – is the term to describe the myelinated axons that resemble the branching of
a tree Meninges – protective layer that covers the brain and spinal cord
- Dura Mater, outer layer; Arachnoid, middle; Pia Mater, inner most deep layer.
- Dura Mater, vertical fold of Dura located in the longitudinal Fissure which forms the Falx
- Vertical fold between two lobes of the Cerebellum forms Falx Cerebelli
- Horizontal fold between the Cerebellum and the occipital lobes forms Tentorium
- ‘Roof’ of dura over the Sella Turcica of the Sphenoid bone forms the Diaphragma Sellae
Saddle Shape contain the pituitary
- Arachnoid Granulation (Villi) extends in opposite directions, into the Superior Sagittal Sinus. sub
space of Arachnoid consists of CSF
- Follows same contour as Dura Mater
- Connected to the underlying Pia Mater via strands called Trabeculae (spider like)
Arachnoid and Pia termed subarachnoid space
- Pia Mater – delicate inner meningeal layer – follows contours of Cerebral Cortex Venous Sinuses – Edges of Dural Folds are venous channels/sinuses, carries deoxygenated blood away
from the brain
- Superior Sagittal Sinus – Top edge of Falx Cerebri
- Inferior Sagittal Sinus – Bottom free edge of Falx Cerebri
- Inferior Sinus continues and meets Superior Sinus via the Straight Sinus
- Occipital Sinus Located in the Falx Cerebelli (Confluence)
- Right and Left Transverse Sinuses located in outer edge of Tentorium Cerebelli
- Continues anteriorly as the Sigmoid Sinuses (S-Shaped), where the Confluence (Straight
sinus + superior sagittal) drains into.
- The Sigmoid Sinuses exit cranial cavity as the L-R Internal Jugular Veins
Inside Sella Turcica – Cavernous sinuses (cave) drain into either sides located at the Diaphragma Sallae
- Draining back to the Sigmoid Sinuses from Cavernous are the L&R Inferior and Superior Petrosal
Ventricles – spaces or cavities withing the brain, these spaces communicate with each other.
L&R Lateral Ventricle – communicate with midline 3 Ventricle via Interventricular Foramina
- 3 Ventricle located between the two Thalami, continues in the mibrain region as Cerebral
Aqueduct - Cerebral Aqueduct cont. in Pons region as the 4 Ventricle Central Canal of the