4PAHPBIO Psychology and the Brain Week 2
Psychology BSc Year 1 Cells and Signalling
CELLS AND SIGNALLING
2.1 THE STRUCTURE AND FUNCTION OF CELLS IN THE NERVOUS
SYSTEM
KEY ORGANELLES IN ANIMAL CELLS
Organelle Function
Nucleus Membrane-bound structure containing most of genetic material
Nucleolus Within the nucleus composed of proteins and nucleic acids
Ribosomes Ribonucleic acids and proteins in the cytoplasm involved in manufacture of
proteins
Rough Endoplasmic Membranous network studded with ribosomes involved in protein synthesis
Reticulum
Smooth Endoplasmic Membranous network involved in lipid synthesis, regulation of calcium and
Reticulum metabolism of carbohydrates
Golgi apparatus Sorts and chemically modifies proteins for specific uses
Mitochondria Membrane enclosed organelle responsible for generating chemical energy
Lysosome Contains enzymes to remove waste
Cytoskeleton (filaments Made up a of different types of tube-like structures responsible for
and microtubes) maintaining shape of cell
Types of Cells Within the Nervous System
Specialised cells in
Nervous System
Glia Neuron
Ependymal Satellite
Macroglia Microglia
cells cells
Oligodendrocytes
OR Astrocytes
Schwann cells
1
,4PAHPBIO Psychology and the Brain Week 2
Psychology BSc Year 1 Cells and Signalling
NEURONS
• There are estimated to be around 86 billion neurons and 86 billion non-
neuronal cells in the human brain (Azevedo et al. 2009)
• They are information processing and information transmitting
• Nerves are bundles of thousands of individual neurons, wrapped in a
protective membrane
The Central Nervous The Peripheral
System (CNS) Nervous System (PNS)
Consists of the brain Consists of the nerves
and spinal cord and most of the sensory
organs
Communicates with the Its sensory neurons
body through nerves gather information from
attached to the brain the environment
and spinal cord
Interneurons lie in the Its motor neurons
CNS between the control contraction of
sensory and motor muscles
neurons
Main Structures
Soma (Cell Body)
• Contains the nucleus and many of the structures involved in the life processes of the cell
Dendrites
• The receivers for messages from other neurons across the synapse (synaptic cleft) from the
terminal button (on the presynaptic cell) to the membrane of another cell (the postsynaptic cell)
• They are of different shapes and sizes
Myelin Sheath
• A fatty substance that covers the axon, providing insulation for the electrical message carried along
the axon membrane
• Myelinated axons appear as white matter in the brain and in nerves
2
, 4PAHPBIO Psychology and the Brain Week 2
Psychology BSc Year 1 Cells and Signalling
Axon
• A long, thin tube that carries axon potentials
(messages)
• The outer surface of an axon carries
information from the cell body to the terminal
buttons
• Axoplasmic transport: a system within the
axon, propelling substances within the axon
rapidly since some axons are extremely long
relative to the size of the soma
o Unlike action potentials which run
along the surface
• Anterograde axoplasmic transport: carries
substances from the soma to the terminal
buttons
• Retrograde axoplasmic transport: carries substances from the terminal buttons back to the soma
Terminal Buttons (or axon terminals)
• Little knobs at the end of the axon branches
• They secrete neurotransmitters once an action potential reaches them
o The actions determine whether an action potential occurs in the receiving cell’s axon
depending on whether it is an excitatory or inhibitory neurotransmitter
• Terminal buttons can form synapses with the membrane of the dendrites or the soma
Other Structures
Cell membrane
• Defines the boundary of the neuron
• Consists of a double layer of lipid molecules
• There are a variety of protein molecules in the membrane
o Some detect substances outside the cell (such as hormones) and pass information about
their presence to the interior of the cell
o Others control access to the interior, allowing or preventing the entrance of substances
o Some are transporters, carrying certain molecules in or out of the cell
3
Psychology BSc Year 1 Cells and Signalling
CELLS AND SIGNALLING
2.1 THE STRUCTURE AND FUNCTION OF CELLS IN THE NERVOUS
SYSTEM
KEY ORGANELLES IN ANIMAL CELLS
Organelle Function
Nucleus Membrane-bound structure containing most of genetic material
Nucleolus Within the nucleus composed of proteins and nucleic acids
Ribosomes Ribonucleic acids and proteins in the cytoplasm involved in manufacture of
proteins
Rough Endoplasmic Membranous network studded with ribosomes involved in protein synthesis
Reticulum
Smooth Endoplasmic Membranous network involved in lipid synthesis, regulation of calcium and
Reticulum metabolism of carbohydrates
Golgi apparatus Sorts and chemically modifies proteins for specific uses
Mitochondria Membrane enclosed organelle responsible for generating chemical energy
Lysosome Contains enzymes to remove waste
Cytoskeleton (filaments Made up a of different types of tube-like structures responsible for
and microtubes) maintaining shape of cell
Types of Cells Within the Nervous System
Specialised cells in
Nervous System
Glia Neuron
Ependymal Satellite
Macroglia Microglia
cells cells
Oligodendrocytes
OR Astrocytes
Schwann cells
1
,4PAHPBIO Psychology and the Brain Week 2
Psychology BSc Year 1 Cells and Signalling
NEURONS
• There are estimated to be around 86 billion neurons and 86 billion non-
neuronal cells in the human brain (Azevedo et al. 2009)
• They are information processing and information transmitting
• Nerves are bundles of thousands of individual neurons, wrapped in a
protective membrane
The Central Nervous The Peripheral
System (CNS) Nervous System (PNS)
Consists of the brain Consists of the nerves
and spinal cord and most of the sensory
organs
Communicates with the Its sensory neurons
body through nerves gather information from
attached to the brain the environment
and spinal cord
Interneurons lie in the Its motor neurons
CNS between the control contraction of
sensory and motor muscles
neurons
Main Structures
Soma (Cell Body)
• Contains the nucleus and many of the structures involved in the life processes of the cell
Dendrites
• The receivers for messages from other neurons across the synapse (synaptic cleft) from the
terminal button (on the presynaptic cell) to the membrane of another cell (the postsynaptic cell)
• They are of different shapes and sizes
Myelin Sheath
• A fatty substance that covers the axon, providing insulation for the electrical message carried along
the axon membrane
• Myelinated axons appear as white matter in the brain and in nerves
2
, 4PAHPBIO Psychology and the Brain Week 2
Psychology BSc Year 1 Cells and Signalling
Axon
• A long, thin tube that carries axon potentials
(messages)
• The outer surface of an axon carries
information from the cell body to the terminal
buttons
• Axoplasmic transport: a system within the
axon, propelling substances within the axon
rapidly since some axons are extremely long
relative to the size of the soma
o Unlike action potentials which run
along the surface
• Anterograde axoplasmic transport: carries
substances from the soma to the terminal
buttons
• Retrograde axoplasmic transport: carries substances from the terminal buttons back to the soma
Terminal Buttons (or axon terminals)
• Little knobs at the end of the axon branches
• They secrete neurotransmitters once an action potential reaches them
o The actions determine whether an action potential occurs in the receiving cell’s axon
depending on whether it is an excitatory or inhibitory neurotransmitter
• Terminal buttons can form synapses with the membrane of the dendrites or the soma
Other Structures
Cell membrane
• Defines the boundary of the neuron
• Consists of a double layer of lipid molecules
• There are a variety of protein molecules in the membrane
o Some detect substances outside the cell (such as hormones) and pass information about
their presence to the interior of the cell
o Others control access to the interior, allowing or preventing the entrance of substances
o Some are transporters, carrying certain molecules in or out of the cell
3
