Lecture 1: Organisation of the nervous system
Learning objectives:
• Gross structure and definitions
• Neurones
• How neurones are organised: nuclei, ganglia, tracts and nerves
• Somatic nervous system
• Automatic nervous system
• Glia- structure and function
The brain and the spinal cord consist of the Central Nervous System (CNS) and the rest (apart from the
gut) is the Peripheral Nervous System (PNS).
Efferent nerves are axons going from the CNS to the rest of the body.
Afferent nerves go to the CNS and carry signals to the brain.
The nervous system consists of nerve cells and the following supporting cells:
• Neuroglia
• Glial
• Glia
Dendrites carry the electrical impulses. The axon can be covered with myelin sheath for faster
conduction and terminals are how cells communication between each other.
The vesicles release neurotransmitter that is complementary to the receptors on the post synaptic
membrane.
Classification of neurones:
Sensory neurones are afferent neurones- they go towards the CNS. The cell body (what contains the
Biology of the Mind- BMSC1210 Page 1
,Sensory neurones are afferent neurones- they go towards the CNS. The cell body (what contains the
nucleus) of the sensory neurone is in the PNS not the CNS. It carries the impulses to the CNS via the
axon. Interneurons are neurones that make connections between neurones. The cell body for motor
neurones are in the CNS. The motor neurone triggers an effector organ like a muscle or gland via the
axon terminal.
Neurotransmitters
Neurones can have different transmitters that either excitatory or inhibitory. Excitatory
neurotransmitters increase the activity of target cells and example is glutamate. Some inhibit, and
decrease the activity of target cells and the most common in the CNS is GABA or gamma-amino butyric
acid.
Neurones come in different shapes and sizes.
• Motor neurones- has large cell body and a lot of dendrites showing a lot of impulses comes into it
• Pyramidal cell from cortex- top of skull, have large dendrites, called pyramidal because when first
discovered the skull made the neurones look like a pyramid. Has branches in local region (picture)
• Purkynge cells- in the cerebellum, has many dendrites.
Neurones in different regions often have different structures. The purkynge cells in the cerebellum in
highly ordered and structures. They are the only cells that send axons out of the cerebellum and the rest
is involved within the cerebellum. The rest include, a basket cell, Golgi cell, granule cell.
Neurones usually come together with other neurones of similar function and therefore are similar
shape. A collection of neurones is called a nucleus. Their axons run and bundle together and this is
called a tract.
Biology of the Mind- BMSC1210 Page 2
,These axons in the tract can be afferent or efferent neurones. They are tract in the CNS but they are just
nerves when in the PNS. The cell bodies also group together in the PNS. But is not called a nucleus but a
ganglia/ganglion when in the PNS.
Types of Glial cells
Glial cells surround neurons and provide support for and insulation between them. They are most
abundant in the CNS and there are different types.
Glial cells types:
• Myelinating glial cells- there are two type, CNS (oligodendrocytes), in PNS (Schwann cells). The
dark part is the layers of the myelin sheath wrapped around many times.
• Astrocytes- they are star shaped and are supporting glial cells. They provide nutrients to the
nervous tissue and their role is in the repair and scarring process of the brain. Some cells have
spines to increase surface area to receive impulses. If there is too much transmitter released,
astrocytes aid in the clean up of extra neurotransmitter. They're the most numerous cell type in
the CNS and aid in the control of blood brain barrier and blood flow.
• Satellite glia- these are astrocytes of the sensory glia. They cover the surface of nerve cell bo
dies in sensory, sympathetic and parasympathetic ganglia.
Biology of the Mind- BMSC1210 Page 3
, • Scavengers- these are microglia. They collect garbage of the nervous system, dead cells and dying
cells. Debris is engulfed by a pair of microglia. When the brain is damaged they are more obviously
activated and more prevalent in the damaged region.
CNS can be classified into the somatic and automatic nervous system:
Somatic nervous system
Cell body in CNS, axon enter the PNS and directly into the target organ.
The axon is myelinated especially in the muscle system to give faster conduction. The neurotransmitter
is acetylcholine. They have axons which are with a cell body. The dorsal root ganglion is the ganglia (cell
body). Another common transmitter release by sensory neurone is glutamate which is released in the
afferent neurone.
Biology of the Mind- BMSC1210 Page 4
Learning objectives:
• Gross structure and definitions
• Neurones
• How neurones are organised: nuclei, ganglia, tracts and nerves
• Somatic nervous system
• Automatic nervous system
• Glia- structure and function
The brain and the spinal cord consist of the Central Nervous System (CNS) and the rest (apart from the
gut) is the Peripheral Nervous System (PNS).
Efferent nerves are axons going from the CNS to the rest of the body.
Afferent nerves go to the CNS and carry signals to the brain.
The nervous system consists of nerve cells and the following supporting cells:
• Neuroglia
• Glial
• Glia
Dendrites carry the electrical impulses. The axon can be covered with myelin sheath for faster
conduction and terminals are how cells communication between each other.
The vesicles release neurotransmitter that is complementary to the receptors on the post synaptic
membrane.
Classification of neurones:
Sensory neurones are afferent neurones- they go towards the CNS. The cell body (what contains the
Biology of the Mind- BMSC1210 Page 1
,Sensory neurones are afferent neurones- they go towards the CNS. The cell body (what contains the
nucleus) of the sensory neurone is in the PNS not the CNS. It carries the impulses to the CNS via the
axon. Interneurons are neurones that make connections between neurones. The cell body for motor
neurones are in the CNS. The motor neurone triggers an effector organ like a muscle or gland via the
axon terminal.
Neurotransmitters
Neurones can have different transmitters that either excitatory or inhibitory. Excitatory
neurotransmitters increase the activity of target cells and example is glutamate. Some inhibit, and
decrease the activity of target cells and the most common in the CNS is GABA or gamma-amino butyric
acid.
Neurones come in different shapes and sizes.
• Motor neurones- has large cell body and a lot of dendrites showing a lot of impulses comes into it
• Pyramidal cell from cortex- top of skull, have large dendrites, called pyramidal because when first
discovered the skull made the neurones look like a pyramid. Has branches in local region (picture)
• Purkynge cells- in the cerebellum, has many dendrites.
Neurones in different regions often have different structures. The purkynge cells in the cerebellum in
highly ordered and structures. They are the only cells that send axons out of the cerebellum and the rest
is involved within the cerebellum. The rest include, a basket cell, Golgi cell, granule cell.
Neurones usually come together with other neurones of similar function and therefore are similar
shape. A collection of neurones is called a nucleus. Their axons run and bundle together and this is
called a tract.
Biology of the Mind- BMSC1210 Page 2
,These axons in the tract can be afferent or efferent neurones. They are tract in the CNS but they are just
nerves when in the PNS. The cell bodies also group together in the PNS. But is not called a nucleus but a
ganglia/ganglion when in the PNS.
Types of Glial cells
Glial cells surround neurons and provide support for and insulation between them. They are most
abundant in the CNS and there are different types.
Glial cells types:
• Myelinating glial cells- there are two type, CNS (oligodendrocytes), in PNS (Schwann cells). The
dark part is the layers of the myelin sheath wrapped around many times.
• Astrocytes- they are star shaped and are supporting glial cells. They provide nutrients to the
nervous tissue and their role is in the repair and scarring process of the brain. Some cells have
spines to increase surface area to receive impulses. If there is too much transmitter released,
astrocytes aid in the clean up of extra neurotransmitter. They're the most numerous cell type in
the CNS and aid in the control of blood brain barrier and blood flow.
• Satellite glia- these are astrocytes of the sensory glia. They cover the surface of nerve cell bo
dies in sensory, sympathetic and parasympathetic ganglia.
Biology of the Mind- BMSC1210 Page 3
, • Scavengers- these are microglia. They collect garbage of the nervous system, dead cells and dying
cells. Debris is engulfed by a pair of microglia. When the brain is damaged they are more obviously
activated and more prevalent in the damaged region.
CNS can be classified into the somatic and automatic nervous system:
Somatic nervous system
Cell body in CNS, axon enter the PNS and directly into the target organ.
The axon is myelinated especially in the muscle system to give faster conduction. The neurotransmitter
is acetylcholine. They have axons which are with a cell body. The dorsal root ganglion is the ganglia (cell
body). Another common transmitter release by sensory neurone is glutamate which is released in the
afferent neurone.
Biology of the Mind- BMSC1210 Page 4
