Download 8.5 Reproductive Hormones

CNS General Structure

Composed of brain and spinal cord

Brain enclosed in skull and surrounded by
a tough three-layer membrane called
meninges

The meninges forms the blood brain
barrier – determines what chemicals reach
the brain
Cerebrospinal Fluid
Circulates between two layers in the
meninges and also in spinal cord
 Functions:

 Shock
absorber
 Transport medium

Spinal Tap – extraction of cerebrospinal
fluid to diagnose infection
Spinal Cord
Carries sensory
nerve messages to
the brain and motor
nerve messages from
the brain to effectors
 Emerges from skull
through opening
called foramen
magnum and extends
down through canal
in backbone

Spinal Cord Organization

Two types of nerve tissue
matter – myelinated nerve fibres from
sensory and motor neurons
 Grey matter – nonmyelinated interneurons
 White

Interneurons form nerve tracts that connect spinal
cord with brain
Dorsal nerve tract – sensory info into
spinal cord
 Ventral nerve tract – motor info from spinal
cord to effectors

The Brain
Brain Structure
Three distinct regions: forebrain, midbrain
and hindbrain
 Forebrain contains:

lobes – receive info about smell
 Cerebrum – major coordinating centre
 Olfactory
Two hemispheres
 Contain regions associated with speech,
reasoning, memory, and other higher functions
 Surface called cerebral cortex – made of grey
matter with many folds to increase surface area

Lobes of the Cerebrum

1.
2.
3.
4.
Cerebral cortex
divided into parts
called lobes:
the frontal lobe
the parietal lobe
the temporal lobe
the occipital lobe
The frontal lobe
is the center for voluntary movement
is called the “motor area” (movement)
includes the prefrontal area,
for intelligence, creativity, memory, and
personality.
The parietal lobe
Collects, recognizes, and organizes
sensations:
feelings of
pain
temperature
touch
position
movement
The temporal lobe
processes auditory (hearing) information
 stores auditory (hearing) and visual
(seeing) memories

The occipital lobe
is at the back of the cerebral hemisphere
involves
vision
visual memory
eye movements
Cerebral Hemispheres





Two cerebral hemispheres are
not mirror images of each
other
Right side associated with
visual patterns or spatial
awareness
Left side linked to verbal skills
Some people may have one
side more dominant which
may affect the way they learn
Corpus callosum – bundle of
nerve fibres connecting two
hemispheres
Midbrain
Less developed than forebrain
 Consists of four spheres of grey matter
 Mostly composed of tracts of nerve fibers
 Relay centre for some eye and ear
reflexes

Hindbrain
Joins to spinal cord
 Major regions:

 Cerebellum
Largest section of hindbrain
 Controls limb movements and balance

 Pons

Relay station passes info between two regions of
cerebellum
 Medulla

oblongata
Controls involuntary muscle action (breathing
movements, heart rate, etc)