Brain & Autonomic Nervous System 1 - (Salvo Chapter 23)
Introduction - Revisiting the Nervous System - A Lifelong Adventure
How does it work?
The nervous system is a cord with wires attached to it and a bulb at the top for more
complex processing. The central cord and the bulb are the “central nervous system”. The
wires outside of the center are the “peripheral nervous system.”
How did this evolve?
In a multicellular organism, the organism must respond as a whole, in a multicellular
way. So the organism evolved a special cell to communicate what's happening to the
cells and coordinate all their responses to changes in the inner and outer environment.
The cells which do that we call neurons.
The system which includes all the neurons and their groupings together we call nervous
system.
Ultimately, it creates a map of our inner and outer world (what’s out there/in here) which
is continually revised on the basis of new experiences. And it stimulates responses to
inner and outer changes.
We are touched by gravity, pressure, light, sound, chemicals (taste, smell, etc), pain,
tension – by all our experiences. We orient to these experiences. The brain then creates a
map of the inner and outer worlds – a picture and sense of what’s out there and what’s in
here (your bodymind). In any case, our brain creates a map, it is not the territory. The
closer the map is to the territory the more effective and useful are our actions.
We are the authors of our lives; we make it up as we go along.
Anatomy
Central Nervous System –
Protected by:
–Skull
–
column
–Meninges
–Cerebrospinal
Spinal cord – ascending (
) and descending (motor) tracts
White matter - myelinated axon bundles make up
of the spinal cord.
Gray matter = cell bodies & unmyelinated axons. In H shape in the center of the
cord.
Ends around L2 but continues as cauda
to S5
Brain –
Brainstem medulla oblongata – inferior-most portion of brainstem – contains
respiratory,
, and vasomotor centers. Also place where the
fibers of one side of brain cross over to the other – “decussation”.
pons and midbrain – they bridge “higher” parts of the brain and the spinal
cord
Diencephalon
Hypothalamus – regulates
and endocrine systems. Controls
hunger, thirst, anger, aggression,
, sexual behavior,
temperature, sleep patterns – “it maintains consciousness.” The size
of a pea; it is perhaps the most powerful influence on the whole
person, through its connection to fundamental “drives.”
Thalamus – the executive “secretary of the diencephalon – relays sensory
information to the
Pituitary – so-called “master” gland of the endocrine system (connected
directly to hypothalamus)
Pineal – linked with biorhythms – secretes
Diencephalon overlaps with “Limbic System” - Located on border between
the cerebrum and the diencephalon - C-shaped structure - wraps around
thalamus and hypothalamus
Functions
1) Emotions
2) Motivation
3)
and
4) Olfaction- smell
Structures
1) Amygdala- almond-shaped, "RAGE CENTER"
2) Limbic lobe- Hippocampus, spatial learning and memory
3) Fornix- tract connecting limbic system to the hypothalamus
Cerebellum – concerned with muscle
, coordination of complex movement,
posture and
– “stored movement programs”
Cerebrum – Largest area of brain
Contains:
–Sensory areas and motor areas
–
centers
–Limbic system (this also overlaps with diencephalon)
governs many emotions
Outer region - Topography characterized by:
–Sulci – grooves, fissures, or deep sulci, separate cerebrum into lobes
– Gyri - elevated
Cerebrum contains right and left
Research indicates they possess specialized functions Left hemisphere
–Language: receptive and expressive
–Reasoning and analytical skills such as
Right hemisphere
–Music
–Art and spatial relationships
–
expression
Corpus callosum –Transverse fibers connecting
Four Lobes:
Frontal - Regulates motor output and cognition
Contains:
–Broca’s areas (left hemisphere only)
production
–Prefrontal cortex - where emotions are
–Precentral gyrus - called “primary motor area”
Parietal – Regulates
, reading, and taste
Governs sensory input - ainly skin and muscles
Contains: postcentral gyrus - “primary somatosensory
area”
Temporal – contains
and olfactory areas
Wernicke area (left hemisphere only) language
comprehension
Occipital lobe –contains
areas
Brain Waves
Levels of consciousness recorded as brain
patterns:
Beta –
consciousness and mental activity
Alpha –
state – calm, attentive, associated with creative
process/meditation
Theta – drowsiness, dreamlike awareness, collective unconscious
Delta – associated with deep
state
Blood-Brain Barrier - Semipermeable wall of blood capillaries
Has thick basement membrane and glial cells
Prevents or slows passage of some chemicals and
blood into CNS
Meninges
Connective tissue coverings surrounding brain and spinal cord
Contains three layers – dura,
, pia (from surface to depth)
Cerebro-spinal fluid - in subarachnoid space and ventricles
Functions include:
–Supplies O2 and nutrients and white blood cells
–Carries away wastes
–Acts as a
absorber
from