Transcript Biological Psychology CH 2

Chapter 2:
Anatomy of Neurons and the
Nervous System
General Organization of the
Nervous System
1.
Central (CNS) = Brain and Spinal Cord
2.
Peripheral (PNS) has two branches
Somatic NS – whole body movement (skeletal
muscles)
Autonomic NS – basic bodily functions
a)
b)
i.
ii.
Sympathetic NS – activating
Parasympathetic NS – calming
Generic Slide
Autonomic Nervous System
1.
2.

Sympathetic – activation of this system prepares
the body for action
Parasympathetic – has the opposite effect, returns
the body to normal, baseline homeostatic function
Anatomical differences between the two systems:
 Parasym. includes cranial and sacral nerves,
while the sympath. consists of thoracic and
lumbar nerves
Protection for your CNS

Protective membranes: meninges

Protective ‘buoy’ system in the CNS, it is made up
of 5 fluid-filled parts


The ventricles & cerebrospinal fluid
The Blood-Brain-Barrier (BBB) is a protective
mechanism of tightly joined endothelial cells lining
all vessels that serve CNS tissue.

This barrier shields the CNS from exposure to many
chemicals, bacteria and viruses.
What is a neuron, exactly?

Neurons are cells that send and receive
information (this action is different than other organ
systems!)
And, where are they located?

Your brain and spinal cord, which together
make up your CENTRAL NERVOUS
SYSTEM (CNS).

The end points (I’ll tell you what that’s called later) of
some neurons are outside of the CNS
Important Structures of a Neural
Cell
The Outside
1.
Plasma Membrane (aka the phospholipid bi-layer)


Lipids – a nice way to say fat
Protein channels – the revolving doors for ions
The Inside
1.
2.
3.
4.
Nucleus – the prize possession
Mitochondria- the cafeteria workers and janitors
Ribosomes – the protein factories
Endoplasmic Reticulum (ER) – the cellular superhighway
Three Types of Neurons
1.
2.
3.
Motor Neurons: the focus is on the ‘output’ in
this kind of cell – information from these cells is
received by muscles and glands
Sensory Neurons: the focus is on the ‘input’
here – these are the cells that allow us to
experience stimuli like light, sound, touch, etc.
Inter-neurons: these are ‘messenger’ boys and
are contained entirely within the CNS.


Local – short messages over short distances
Relay - connect circuits of neurons with other circuits in
different parts of the brain
Features of a Neural Cell
Neurons have all the structures on a normal
cell, with a funny shape and a few extras:

1.
Soma = the cell body- all cells have a ‘body’, but because of
the unique shape of neural cells, their cell bodies get a special
name.
2.
3.
4.
5.
Dendrites = the ‘incoming/ receiving’ end of the cell
Axons – the ‘outgoing’ end of the cell ( at least on motor
neurons)– electrical conduction occurs along the axon.
Presynaptic terminals – the end-point of the axon.
Electrical stimulation here causes chemical release.
Synapses = spaces between cells – chemical
communication between cells occurs here.
Example of a Unipolar Motor Neuron
More about Axons
1.
Most axons are covered in a myelin sheath

2.
Nodes of Ranvier (breaks/ spaces in the myelin)
Information traveling down an Axon can be
described two ways:
a)
as moving towards a structure (afferent)

b)
All sensory neurons are afferent to the CNS (i.e.
information flows into the CNS from the sensory
organs)
as moving away from a structure (efferent)

All motor neurons are efferent to the CNS (i.e.
information only flows out from the CNS to the
muscles)
Helper Cells in the CNS: GLIA
1.
Astrocytes – star shaped cells that help with
chemical ‘reuptake’ of several axon terminals

Radial Glia – embryonic astro’s that guide neuron
growth
2.
Microglia – little janitors, act like immune cells
3.
Oligodenrocytes (in CNS) & Schwann cells
(in the periphery) build myelin sheaths around
neurons/nerves, respectively.
Directions in the CNS

There are 3 spatial planes the CNS is described
on:
a)
Coronal plane = front to back

b)
Sagital plane = side to side

c)
Medial vs. Lateral
Horizontal place = top to bottom


Ventral vs. Dorsal
Anterior vs. Posterior
Location of structures are often described in
relation to one another: anterior/posterior,
superior/inferior, proximal/distal,
ipsalateral/contralateral
Spinal Cord Anatomy
1.
Axons that enter the dorsal side of the spinal
cord are on their way IN, carrying sensory
information
2.
Axon that leave the ventral side of the spinal
cord are on their way OUT to give
information from the brain to the muscles &
glands.
More Fun Facts about the Cord
1.
The center of your spinal cord contains the
soma and dendrites belonging to ganglia and
other neurons in the cord= gray matter
2.
The white matter surrounding the gray
matter is the myelinated axons of neurons
sending their info up to the brain.
Moving on to Brain Anatomy
Before we start, I want you to know
there are two ways we talk about brain
anatomy:

1.
We talk about structures – physical
landmarks
2.
And we also talk about systems – circuits
of neurons that go a particular place or
deliver a particular kind of information to
many other places
The whole brain…



We spend a lot of time dividing up the different
parts of the brain, but it is very important to
remember that all parts work in concert,
constantly exchanging information.
The study of how different sensations lead to a
unified perception of something is called the
binding problem
The idea that we use only 10% of our brain is
absolutely ridiculous! Which 90% would you
like to give up?
Structures in the Brain Stem
1.
Medulla – considered the transition point from
the cord to the brain, controls many autonomic,
‘vegetative’ functions
2.
Pons – crossover point for contralateral control
3.
Cerebellum – ‘little brain’, muscle coordination
& perceptual tasks
More about the Stem

Two systems in the stem:



the reticular formation (arousal/ attention)
raphe system (responsiveness to stimuli)
The cranial nerves (except #1) all exit the brain
from the stem
12 Cranial Nerves
I.
II.
III.
IV.
V.
VI.
Olfactory = smell
Optic = vision
Oculomotor =
pupil
Trochlear = eye
movement
Trigeminal =
eating/ feeling face
Abducens = eye
movement
VII. Facial – taste front 2/3
of tongue
VIII. Statoacoustic –
hearing, balance
IX. Glossopharyngeal –
taste back of tongue,
muscle control
X. Vagus – sensation and
motor control of
digestive organs
XI. Accessory – neck and
shoulders
XII. Hypoglossal - tongue
Midbrain
1.
The colliculi (inferior and superior) routing sensory info.
2.
Substantia Nigra – very important in
voluntary movement

Cell death occurs here in Parkinson’s Disease
Forebrain
1.
The limbic system resides in the forebrain:




Olfactory bulb – smell information
Hypothalamus – ‘drive’ control
Amygdala – emotion & fear responding
Hippocampus - memory
2.
Thalamus – relay station for (almost) all
sensory information before it heads to other
parts of the brain
3.
Pituitary gland
Finally: The Cortex
1.
Cortex means ‘bark’ (as in tree) in Latin



2.
3.
4.
Appearance
Outer layer
The wrinkled, grey matter surface of the brain
The cortex is made up of 6 layers of cells (laminae)
Neurons are also arranged in columns that go
through several laminae and contain cells of similar
function.
Two hemispheres (right and left) – connected by
the corpus callosum
More Organization of the cortex

The cortex is divided into 4 lobes (by general
function)




Frontal lobe – prefrontal cortex (planning &
judging), motor cortex, language production
(Broca’s area)
Parietal lobe – sensory cortex & language
production
Occipital lobe – visual center
Temporal lobe – auditory center & language
understanding (Wernicke’s area).
Examining Brain Function
1.
2.
3.
4.
5.
6.
First efforts by Gall - Phrenology
Computerized Imaging
a) CT/CAT scan = X-ray
b) PET scan = radiolabled glucose
c) regional cerebral blood flow
d) fMRI
Study the functional effects of brain injury
Brain stimulation
EEG – task related ERPs (very imprecise)
Examining brains of extraordinary people (posthumously) and comparing to normals
Next Week: CHAPTER 3
Neural Communication