BIOPSYCHOLOGY 8e John P.J. Pinel
Copyright © Pearson Education 2011
A communication
network consisting of
nerve cells, both inside and
outside of the brain and spinal
cord
e r v o u s! s y s t e m!
Copyright © Pearson Education 2011
General Layout of the Nervous System
The major divisions of the nervous system. “A system of twos.”
Copyright © Pearson Education 2011
General Layout of the Nervous System
Central Nervous System (CNS)
• Brain (in the skull) • Spinal Cord (in the spine)
Peripheral Nervous System (PNS)
• Located outside of the skull and spine
• Serves to bring information into the CNS and carry signals out of the CNS
Copyright © Pearson Education 2011
General Layout of the Nervous System
Peripheral Nervous System • Somatic Nervous System
Afferent nerves (sensory) Efferent nerves (motor)
• Autonomic Nervous System Regulates internal
environment Afferent nerves (sensory
signals from internal organs)
Two types of efferent nerves (motor nerves from to internal organs) Sympathetic and
parasympathetic efferents
Copyright © Pearson Education 2011
Autonomic Nervous System
Two types of efferent nerves:
Sympathetic and parasympathetic nerves generally have opposite effects
Each autonomic target gets opposing sym and parasym input
Two-stage neural paths, neuron exiting the CNS synapses on a second-stage neuron before the target organ
Copyright © Pearson Education 2011
SYMPATHETIC EFFERENTS PARASYMPATHETIC EFFERENTS
Cranial and sacral
“Rest and digest”
Second stage neurons are near the target organ
Autonomic Nervous System
Thoracic and lumbar
“Fight or flight”
Second stage neurons are far from the target organ
Copyright © Pearson Education 2011
Autonomic Nervous System
Copyright © Pearson Education 2011
Meninges, Ventricles, and Cerebrospinal Fluid (CSF)
CNS encased in bone and covered by three meninges
• Dura mater – tough outer membrane
• Arachnoid membrane – web-like
• Pia mater – adheres to CNS surface
Cerebrospinal fluid (CSF) • Fluid serves as cushion – Fills ventricles, subarachnoid
space and central canal
Copyright © Pearson Education 2011
Protecting the Brain
Copyright © Pearson Education 2011
The Cerebral Ventricles
Copyright © Pearson Education 2011
Protecting the Brain
Chemical protection
• The blood-brain barrier – tightly-packed cells of blood vessel walls prevent entry of many molecules
Physical protection
• Skull • Meninges • Cerebrospinal fluid
(CSF)
Copyright © Pearson Education 2011
The human brain Neurons
Neurons and the Human Brain
An amazingly intricate network of neurons
Cells that receive and transmit electrochemical signals
Copyright © Pearson Education 2011
Neurons
Specialized cells for the reception, conduction, and transmission of electrochemical signals
Many sizes and shapes
Cells of the Nervous System: Anatomy of Neurons
Copyright © Pearson Education 2011
The major external features of a typical neuron
Copyright © Pearson Education 2011
The major internal features of a typical neuron
Copyright © Pearson Education 2011
The cell membrane is a lipid bilayer with signal proteins and channel proteins embedded in it
Cells of the Nervous System: Anatomy of Neurons
Copyright © Pearson Education 2011
A unipolar neuron, a bipolar neuron, a multipolar neuron, and an interneuron
Cells of the Nervous System: Anatomy of Neurons
Copyright © Pearson Education 2011
Glial cells • Support neurons • Outnumber neurons
10:1 (apparently) • Recent evidence for
glial communication and modulatory effects of glia on neuronal communication
• Much ongoing research in this area
Glial Cells: The Forgotten Cells
Copyright © Pearson Education 2011
1
2
3
4
Oligodendrocytes – extensions rich in myelin create myelin sheaths in CNS
Schwann cells – similar to function of oligodendrocytes but in PNS, can guide axonal regeneration (clinical applications) Astrocytes – largest glia, star-shaped, many functions such as support and protection (and signalling)
Microglia – involved in response to injury or disease
Four Classes of Glial Cells
Copyright © Pearson Education 2011
The myelination of CNS axons by an oligodendrocyte and the myelination of PNS axons by Schwann cells
Glial Cells: The Forgotten Cells
Copyright © Pearson Education 2011
Terminology
CNS PNS
Myelin-providing glia
Oligodendrocytes Schwann cells
Clusters of cell bodies (activity)
Nuclei (singular nucleus)
Ganglia (singular ganglion)
Bundles of axons (pathways)
Tracts Nerves
Glial Cells: The Forgotten Cells
Copyright © Pearson Education 2011
Figure 3.14
Directions in the Vertebrate Nervous System
Anatomical directions in a representative vertebrate (cat).
Copyright © Pearson Education 2011
Figure 3.15
Directions in the Vertebrate Nervous System
Anatomical directions in a human
Copyright © Pearson Education 2011
Anatomical directions ignore the fact that humans walk upright. Therefore, top of the head is both “dorsal” (back) and “superior” (top)
Other directions: • Medial – toward the middle • Lateral – toward the side • Proximal – close • Distal – far
Directions in the Vertebrate Nervous System
Copyright © Pearson Education 2011
Sections of the Brain
• Horizontal – a slice parallel to the ground
• Frontal (coronal) – slicing bread or salami
• Sagittal – a midsagittal section separates the left and right halves
Copyright © Pearson Education 2011
Spinal Cord
Dorsal – afferent, sensory
Gray matter – inner component, primarily cell bodies
White matter – outer area, mainly myelinated axons
Ventral – efferent, motor
Copyright © Pearson Education 2011
Five Major Divisions of the Brain
Copyright © Pearson Education 2011
Five Major Divisions of the Brain
Copyright © Pearson Education 2011
Major Structures of the Brain
Myelencephalon = medulla • Composed largely of tracts • Origin of the reticular
formation • Arousal, sleep, attention,
muscle tone, vital reflexes
Metencephalon • Many tracts • Pons – ventral surface
• Functions similar to medulla
• Cerebellum – coordination
Copyright © Pearson Education 2011
Structures of the human myelencephalon (medulla) and metencephalon
Copyright © Pearson Education 2011
Major Structures of the Brain
Mesencephalon = midbrain • tectum has inferior (auditory) and superior
colliculi (visual) • on dorsal surface
• tegmentum has • periaqueductal gray (pain), • substantia nigra, and red nucleus
(sensorimotor • medial and ventral
Diencephalon • Thalamus (sensory relay to cortex • Hypothalamus (controls ANS, endocrine
systems
Copyright © Pearson Education 2011
The human mesencephalon (midbrain)
Major Structures of the Brain
Copyright © Pearson Education 2011
The human diencephalon
Major Structures of the Brain
Copyright © Pearson Education 2011
Telencephalon – Cerebral Cortex
Convolutions serve to increase surface area Outer covering unmyelinated grey matter Layer beneath myelinated axons – white matter
Longitudinal fissure – a groove that separates right and left hemispheres
Corpus callosum – largest hemisphere-connecting tract
Copyright © Pearson Education 2011
e r e b r a l c o r t e x!
Outermost part of forebrain, responsible for analyzing sensory processing and higher brain functions
Copyright © Pearson Education 2011
The major fissures of the human cerebral cortex
The lobes of the cerebral hemisphere
Copyright © Pearson Education 2011
Telencephalon – Subcortical Structures
Limbic system – regulation of motivated behaviors • Mammillary bodies,
hippocampus, amygdala, fornix, cingulate, septum
Basal ganglia motor system • Amygdala, striatum (caudate
nucleus + putamen), globus pallidus
Copyright © Pearson Education 2011
The major structures of the limbic system: amygdala, hippocampus, cingulate cortex, fornix, septum, and mammillary body
Regulation of motivated behaviours, emotion and memory
The Limbic System
Copyright © Pearson Education 2011
Structures in the forebrain that help to control movement • Damage to the basal ganglia contributes to Parkinson’s disease.
• The basal ganglia also allow us to perform voluntary movements to obtain rewards.
• Many implications: • http://www.youtube.com/watch?v=crh_LGBNwSA
The Basal Ganglia
Copyright © Pearson Education 2011
The basal ganglia: amygdala, striatum (caudate plus putamen) and globus pallidus
The Basal Ganglia
Copyright © Pearson Education 2011
Summary of major brain structures