Download Allison Bynum Neurobiology A.1 – A.3 Allison Bynum A.1 Neural

Neurobiology A.1 – A.3
Allison Bynum
A.1 Neural Development
Allison Bynum
A.1 – The neural tube of embryonic chordates
is formed by infolding of ectoderm followed by
elongating of the tube.

Neural folds converge
Neural plate elongates and thickens
The neural crest forms as the tube is forming
Neural tube is formed and the outer layer of the ectoderm
becomes the epidermis
Neuron differentiation
A.1 – Neurons are initially produced by
differentiating in the neural tube.
Neurons – carry the messages by electrical impulses
Glial cells – provide structural and nourishing support for neurons
(also act as insulators(Myelin Sheath))
A.1 – Immature neurons migrate to a final
destination.
 Glial cells provide a way
for the immature neurons
to travel to destinations.
 Maturation of the neurons
occurs after the migration.
A.1 – An axon grows from each immature
neuron in response to chemical stimuli.
Axon
growth
CAMs help to
attract axons to
their targets
CAMs are
released into the
extracellular
space.
Some signals from
CAMs interfere
with other axons
and repel them.
A.1 – Some axons extend beyond the neural
tube to reach other parts of the body.
 Motor neurons –
extend beyond the
CNS to become the
peripheral nervous
system for voluntary
movements
A.1 – A developing neuron forms multiple
synapse.
 Neurons try to form
synapses with nearby target
cells and test the connection.
 The synapse is eliminated if
it isn’t successful. (neural
pruning)
A.1 – Synapse that are not used do not persist.
A.1 – Neural pruning involves the loss of unused neurons.
 Neural pruning – the
elimination of unused
or unnecessary
synapses
A.1 – The plasticity of the nervous system
allows it to change with experience.
 Brain plasticity – is the brain’s ability to change and adapt as a
result of experience
 Brain plasticity is higher in younger children and decreases with
age. The adult brain is more resistant to change.
A.2 The Human Brain
A.2 – The anterior part of the neural tube
expands to form the brain.
 Nerve cells migrate to the outer
edge of the neural tube and cause
the walls to thicken.
 The neural tube develops into the
brain and spinal cord. The anterior
end of the tube expands to form the
cerebral hemispheres of the brain,
while the posterior end forms the
spinal cord and the other parts of the
brain.
A.2 – Different parts of the brain have specific
roles.
Part of the
Brain
Function
Cerebral
hemispheres
Higher complex
functions/problem solving
Hypothalamus
Maintains hormone homeostasis
and the pituitary gland
Cerebellum
Coordinates unconscious
functions(not vital)/balance and
movement
Medulla
Oblongata
Controls automatic vital
functions(heart beat and
breathing)
Pituitary
Gland
Hormone storage and
secretion/controlled by
hypothalamus
A.2 – The autonomic nervous system controls involuntary
processes in the body using centers located in the brainstem.
 Autonomic nervous
system – is part of the
peripheral nervous
system; controls
involuntary functions;
regulates gland activities,
smooth muscles, and the
heart
 The sympathetic and
parasympathetic systems
are divisions of the ANS.
Sympathetic
Parasympathetic
Important for
emergencies
Returning to normal
“Fight or Flight”
response
Relaxing
Noradrenaline
Acetylcholine
Excitatory
Inhibitory
A.2 – The cerebral cortex forms a larger portion of
the brain and is more highly developed in humans
than other animals.
 Cerebral cortex – the thin layer of grey matter covering the
cerebral hemispheres; contains 75% of the body’s neurons
 Responsibilities include:
 Reasoning
 Language
 Complex thought
 Visual processing
 Motor movement
 Remembering
 Speech
A.2 – The human cerebral cortex has become enlarged
principally by an increase in total area with extensive folding
to accommodate it within the cranium
 The folds in the
brain help to
increase the
surface area of
the cerebral
cortex to allow
more neurons.
 Parts of the
cerebral cortex
have specific
functions.
A.2 – The cerebral hemispheres are
responsible for higher order functions.
 The cerebrum is
responsible for the
problem solving and
higher thinking
A.2 – The left cerebral hemisphere receives sensory input from sensory
receptors in the right side of the body and the right side of the visual field in both
eyes, and vice versa for the right hemisphere.
Left hemisphere receives
sensory info from:
Right Hemisphere receives
sensory info from:
Right eye
Left eye
Right field of vision(some
parts will cross over with left
field of vision)
Left field of vision(some
parts will cross over with
right field of vision)
Right side of body
Left side of body
A.2 – The left cerebral hemisphere controls muscle
contraction in the right side of the body, and vice versa for
the right hemisphere.
 The motor neurons for
the left cerebral
hemisphere connect to
the muscles on the right
side and vice versa.
A.2 – Brain metabolism requires large energy
inputs.
 Glucose is needed constantly for
the brain because neurons
cannot store it. The energy is
used up very rapidly because of
the mental activity.
 Carbohydrates like fruits,
vegetables, grains and dairy are
some of the best sources for
glucose.
A.3
Receptors detect changes in the
environment.
Rods and cones are photoreceptors located
in the retina.
Rods and cones differ in their sensitivities to
light intensities and wavelengths.
Bipolar cells send the impulses from the rods
and cones to ganglion cells.
Ganglion cells send messages to the brain
via the optic nerve.
The information from the right field of vision
from both eyes is sent to the left part of the
visual cortex and vice versa.
Structure in the middle ear transit and amplify
sound.
Sensory hairs of the cochlea detect sounds of
specific wavelengths.
Impulses caused by sound perception are
transmitted to the brain via the auditory
nerve.
Hairs in the semicircular canals detect
movement of the head.
Resources
 http://www.bodbot.com/Cognitive_Health.html
 http://www.dreamstime.com/royalty-free-stock-images-motor-neuronvector-diagram-structure-include-dendrites-cell-body-nucleus-axon-myelinsheath-nodes-ranvier-end-image35181499
 http://www.neurosignallab.com/
 http://america.pink/synaptic-pruning_4248821.html
 http://womenoutandabout.net/summer-musings-pruning-by-christine-ccantrell/
 https://1mkturin.wordpress.com/category/science-of-music/page/2/
 http://www.sunscientific.com/What-is-ANS.html
 http://zzanatomy.yolasite.com/
 http://scicurious.scientopia.org/2011/02/23/cell-phones-coming-for-yourbrain-cells-since-well-maybe-not/