NERVOUS SYSTEM 1
Evolution of the Nervous System
o As animals evolved - greater need for an increasingly complex & adept nervous system
To compete: escape danger/predators & find food/shelter/mates
Strong natural selection pressure for a more refined, competent nervous system
o Comparative Neuroscience
Invertebrates: simple nervous system, fewer
neurons, less complex networks
Then: cephalization - development of an
anterior head where sensory organs & nervous tissues
are concentrated
Nerve nets - loose mesh of neurons found in
radially symmetrical animals
Nerve cord - bundle of nerves which extend
from the central ganglia to the rest of the body
--> trend toward bilateral symmetry of
nervous system and body
Body parts are mirror images on the
either side of the midline
Organization of the nervous system, such as paired nerves linking lobes in brain with
specific muscles and receptors--> allow for sophisticated sensory processing
Ex) Animals: coordinated, rapid movement to hunt prey, escape predators
Ganglia - functional clusters of neurons
Phyla?
o Vertebrate Nervous System - pattern of development determines the
structure of the nervous system
Temporal & Spatial Gene Expression - Hox Genes-->Encode for
proteins that regulate transcription of genes
Have 60 AA sequence called homeobox --> encodes for a
homeodomain--> part of the protein that binds to DNA
Chromosome expression aligns with different hox genes
anterior/posterior part of animal--> start to specify regions of the adult
Colored segments=similar genes--> encode for similar proteins that
specify the body plan in each organism
o Neural tube formation:
Neural tube=precursor of the CNS
Neural crest cells migrate and differentiate
into a number of varied cell types
Neural plate involutes
Ex) Human Embryo--> 3 weeks after
conception (~3mm)--> brain, spinal cord, heart and other
organs begin to form
Ex) Gene expression during neural tube
formation: cadherin gene
Calcium dependent adhesion
molecules - transmembrane proteins
Role in cell adhesion--> ensures
that cells within tissues are bound together
Dependent on Ca 2+ to function
, NERVOUS SYSTEM 2
The Brain
o General functions:
Receive information
Integrate information
Store information
Retrieve information
o Has specialized regions to carry out
functions
Ex) Somatosensory -touch,
pain, temperature, body position
o Blood Brain Barrier - separation of
circulating blood and cerebrospinal fluid (CSF)
Occurs along capillaries and consists of
tight junctions around the capillaries that do not
exist in normal circulation
Endothelial cells - restrict the diffusion
of microscopic objects (bacteria etc.) and
large/hydrophilic molecules into the CSF
Allow diffusion of small
hydrophobic molecules (O2, hormones,
CO2)
Cells of the barrier ACTIVELY transport metabolic products such as glucose across the barrier
with specific proteins
o Meninges - layers of connective tissue (membranes) covering the brain & spinal cord
Pia, arachnoid, dura mater (most outside)
Function: support blood vessels, contain CSF, "pad" between brain and skull
o Cerebrospinal fluid (CSF) - clear colorless fluid produced in the choroid plexus (complex of glial cells-called
ependymal cells)
Circulates nutrients & chemicals filtered from the blood
Removes waste products from the brain
Occupies the subarachnoid space (space between arachnoid and pia) and the ventricular system
Protect brain from striking cranium when head is jolted
Provides buoyancy and support to the brain against gravity
Buoyancy protects brain since brain and CSF are similar in density--> makes brain float in
neutral buoyancy, suspended in the CSF
Allows brain to attain decent size & weight without resting on the flow of the cranium
(would kill nervous tissue)
Provides chemical balance/stability
o Ventricular system
Ventricles - cavities in the brain filled with CSF
Subdural hematoma - swelling containing blood - ventricle gets pushed in and absorbs shock
Alzheimer's Disease: ventricular volume is significantly higher than healthy subjects - space bigger
because have less actual brain tissue
o Forebrain - forms cerebrum has L & R hemispheres
Left hemisphere - responds to sensory signals from the right side of body & controls movements
of right side of body (vice versa)
Focus on details (recognizing particular face in crowd)
Spoken & written language, abstract reasoning, math
Right hemisphere - focus on broad background (understanding relative position of objects in
space)
Intuitive thinking, conceptualization, music, art
Hemispheres connected by thick axon bundles called corpus callosum
Cerebral Cortex - outermost thin layer of grey matter covering a core of white matter
in mammals: comprised of 6 layers of neurons, 2-4 mm thick in humans
Grey matter: neuron cell bodies and dendrites
White matter: axons (many axons have myelin sheaths
Evolution of the Nervous System
o As animals evolved - greater need for an increasingly complex & adept nervous system
To compete: escape danger/predators & find food/shelter/mates
Strong natural selection pressure for a more refined, competent nervous system
o Comparative Neuroscience
Invertebrates: simple nervous system, fewer
neurons, less complex networks
Then: cephalization - development of an
anterior head where sensory organs & nervous tissues
are concentrated
Nerve nets - loose mesh of neurons found in
radially symmetrical animals
Nerve cord - bundle of nerves which extend
from the central ganglia to the rest of the body
--> trend toward bilateral symmetry of
nervous system and body
Body parts are mirror images on the
either side of the midline
Organization of the nervous system, such as paired nerves linking lobes in brain with
specific muscles and receptors--> allow for sophisticated sensory processing
Ex) Animals: coordinated, rapid movement to hunt prey, escape predators
Ganglia - functional clusters of neurons
Phyla?
o Vertebrate Nervous System - pattern of development determines the
structure of the nervous system
Temporal & Spatial Gene Expression - Hox Genes-->Encode for
proteins that regulate transcription of genes
Have 60 AA sequence called homeobox --> encodes for a
homeodomain--> part of the protein that binds to DNA
Chromosome expression aligns with different hox genes
anterior/posterior part of animal--> start to specify regions of the adult
Colored segments=similar genes--> encode for similar proteins that
specify the body plan in each organism
o Neural tube formation:
Neural tube=precursor of the CNS
Neural crest cells migrate and differentiate
into a number of varied cell types
Neural plate involutes
Ex) Human Embryo--> 3 weeks after
conception (~3mm)--> brain, spinal cord, heart and other
organs begin to form
Ex) Gene expression during neural tube
formation: cadherin gene
Calcium dependent adhesion
molecules - transmembrane proteins
Role in cell adhesion--> ensures
that cells within tissues are bound together
Dependent on Ca 2+ to function
, NERVOUS SYSTEM 2
The Brain
o General functions:
Receive information
Integrate information
Store information
Retrieve information
o Has specialized regions to carry out
functions
Ex) Somatosensory -touch,
pain, temperature, body position
o Blood Brain Barrier - separation of
circulating blood and cerebrospinal fluid (CSF)
Occurs along capillaries and consists of
tight junctions around the capillaries that do not
exist in normal circulation
Endothelial cells - restrict the diffusion
of microscopic objects (bacteria etc.) and
large/hydrophilic molecules into the CSF
Allow diffusion of small
hydrophobic molecules (O2, hormones,
CO2)
Cells of the barrier ACTIVELY transport metabolic products such as glucose across the barrier
with specific proteins
o Meninges - layers of connective tissue (membranes) covering the brain & spinal cord
Pia, arachnoid, dura mater (most outside)
Function: support blood vessels, contain CSF, "pad" between brain and skull
o Cerebrospinal fluid (CSF) - clear colorless fluid produced in the choroid plexus (complex of glial cells-called
ependymal cells)
Circulates nutrients & chemicals filtered from the blood
Removes waste products from the brain
Occupies the subarachnoid space (space between arachnoid and pia) and the ventricular system
Protect brain from striking cranium when head is jolted
Provides buoyancy and support to the brain against gravity
Buoyancy protects brain since brain and CSF are similar in density--> makes brain float in
neutral buoyancy, suspended in the CSF
Allows brain to attain decent size & weight without resting on the flow of the cranium
(would kill nervous tissue)
Provides chemical balance/stability
o Ventricular system
Ventricles - cavities in the brain filled with CSF
Subdural hematoma - swelling containing blood - ventricle gets pushed in and absorbs shock
Alzheimer's Disease: ventricular volume is significantly higher than healthy subjects - space bigger
because have less actual brain tissue
o Forebrain - forms cerebrum has L & R hemispheres
Left hemisphere - responds to sensory signals from the right side of body & controls movements
of right side of body (vice versa)
Focus on details (recognizing particular face in crowd)
Spoken & written language, abstract reasoning, math
Right hemisphere - focus on broad background (understanding relative position of objects in
space)
Intuitive thinking, conceptualization, music, art
Hemispheres connected by thick axon bundles called corpus callosum
Cerebral Cortex - outermost thin layer of grey matter covering a core of white matter
in mammals: comprised of 6 layers of neurons, 2-4 mm thick in humans
Grey matter: neuron cell bodies and dendrites
White matter: axons (many axons have myelin sheaths
