The Mammalian Brain

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The Mammalian Brain
9.3 The Central Nervous System p. 427 - 434
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The Central Nervous System

• Consists of the brain and the spinal cord. These
  organs are protected by
• 1) skull and vertebrae
• 2) cerebrospinal fluid cushions the brain and
  spinal cord
• 3) meninges are protective membranes that
  surround the CNS

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The Spinal Cord

• Contains interneurons that link the sensory and
  motor pathways. These neurons carry information
  to and from the brain. The spinal cord contains
  31 segments, each of which has a pair of spinal
  nerves.
• The spinal cord contains white matter (bundles
  of myelinated axons of sensory and motor
  neurons), and grey matter (unmyelinated
  interneurons and the dendrites of motor neurons).

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• Cerebrospinal fluid surrounds CNS (brain and
  spinal cord) acts as a sock absorber and
  transport medium (nutrients, chemicals, removal
  of wastes, etc) is a connection between CNS and
  endocrine system

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The Brain

• The human brain contains three distinct areas
  the forebrain, the midbrain, and the hindbrain.
• is protected by the skull and meninges (a
  protective three layer thick membrane that
  surrounds the brain and spinal cord)
• meninges controls which chemicals can ultimately
  reach the brain

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• The meninges (membrane) covers the surface of the
  cerebrum
• The most common symptoms of meningitis are
  headache and neck stiffness associated with fever
• Meningitis is diagnosed using a technique called
  lumbar puncture

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• The meninges is composed of 3 membranes
• the dura mater, the tough outer membrane that
  adheres to the skull
• The arachnoid, the weblike middle layer that
  reabsorbs cerebrospinal fluid
• And the pia mater, the innermost layer that
  contains many blood vessels and closely covers
  the brain and spinal cord

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Which region is responsible for vision? Which is
responsible for hearing?
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Sections of the Brain

• Forebrain
• reason, intellect, memory, language, and
  personality
• information on right side does not info on left
• generally on right (visual patterns or spatial
  awareness)
• generally on left (verbal skills)
• hemispheres are joined by a bundle of nerves
  called corpus collosum allows communication
  between hemispheres

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Sections Function
Olfactory lobes (x2) process information about smell
Cerebrum 2 hemisphere largest and most developed coordinates sensory info motor actions largest and most developed divided into four (4) lobes (see below)
Cerebral Cortex surface of cerebrum made of grey matter highly folded (deep folds fissures)
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Why is the frontal lobe called frontal?
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What forms the largest part of the brain?

• cerebrum is composed of 2 hemispheres

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Why are we smarter than fish?

• We share a common ancestor
• However, our forebrains are much larger
  (cerebrum speech, reasoning, memory, and
  personality)

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an elephant never forgets

• The cerebrum (area of memory) is well developed
  in the elephant
• The elephants cerebrum is larger than humans

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• The increased surface area allows more nerve
  cells, which in turn allows for more learning and
  a greater range of behaviours.
• The grey matter of the human cortex is less than
  5 mm thick, but in mass makes up more than 80 of
  the brain.

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• The central fissure extends from the top of each
  cerebral hemisphere to the lateral fissure

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Midbrain

• located directly below cerebral cortex
• relay center for eye and ear reflexes

Sections Function
Thalamus integrative center connecting many different parts of the brain together
Hypothalamus master control center of automatic nervous system (ANS) integrates the ANS and endocrine system
Hippocampus short term memory
Basal Ganglia many parts responsible for crude motor movements injury leads to rigidity, Parkinsons and Huntingtons disease mediates emotional feelings mediates between forebrain hindbrain
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The Hindbrain
http//outreach.mcb.harvard.edu/animations/brainan
atomy.swf
Sections Function
Medulla Oblongata joins spinal cord to cerebellum controls involuntary muscle action coordinating centre for the ANS e.g breathing, heart rate, blood vessel activity, swallowing, vomiting, digestion)
Pons bridges acts as relay station by sending nerve messages between the cerebellum and medulla
Cerebellum controls limb movements, balance and muscle tone e.g. walking, hand-eye coordination, etc)
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• Cerebellum
• What does convoluted mean?
• Damage to the cerebellum can lead to loss of
  coordination of motor movement

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• brain stem
• basic attention, arousal, and consciousness

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• The frontal lobe
• higher intellect, foresight and judgment, primary
  motor area and motor area for speech
• In 1890, psychiatrist Gottlieb Burckhardt removed
  pieces of the frontal lobes of six patients in a
  psychiatric hospital in Switzerland.

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• The parietal lobe
• touch, temperature, and taste, and association
  areas for emotions, reading, and interpreting
  speech

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• Temporal
• smell, hearing and auditory association areas

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Occipital vision and visual association areas
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• The corpus callosum
• contains nerve fibers that connect the right and
  left sides of the brain

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• The corpus callosum is white because it consists
  of myelinated nerve fibres.

Sheep
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• The medulla oblongata
• controls heart and breathing rates and vasomotion
  (the dilation and constriction of blood vessels)
  to ensure blood is distributed more to active
  tissues than inactive ones.

sheep
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• The pons is an important relay center for sensory
  and motor nerve fibers connecting the medulla
  oblongata and the cerebellum
• The pons also stimulates exhalation during
  prolonged inhalation of breath-holding.

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• The hypothalamus is an important center for the
  homeostatic regulation of several activities.
• It produces the hormones oxytocin and
  antidiuretic hormone secreted by the posterior
  pituitary gland.
• Other functions include the regulation of body
  temperature, water retention, appetitie,
  digestive secretions, sexual activity, and
  emotions such as fear and rage.

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PRACTICE!!!1. List the four regions of the
cerebral cortex and state the function of each.

1. Frontal lobe motor areas control movement of
   voluntary muscles (e.g., walking and speech).
   Association areas are linked to intellectual
   activities and personality.

b) Temporal lobe Sensory areas are associated
with vision and hearing. Association areas are
linked to memory and interpretation of sensory
information.
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• c) Parietal lobe Sensory areas are associated
  with touch and temperature awareness.
  Association areas have been linked to emotions
  and interpreting speech.

d) Occipital lobe Sensory areas are associated
with vision. Association areas interpret visual
information.
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3. Name the different parts of the brain on page
434 and give functions.

• T- cerebrum stores sensory information and
  initiates voluntary motor activities
• S-pons acts as a relay station by sending nerve
  messages between the cerebellum and the medulla
• R- medulla oblongata site of autonomic nerve
  control
• V- cerebellum coordinates muscle movent

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4. A physician makes an incision completely
through the corpus callosum. How might this
affect the patient?

• The right and left sides of the brain will not be
  able to communicate.
• the left hand does not know what the right hand
  is doing
• Has been considered as a treatment for severe
  cases of epilepsy

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Phineas P. Gage (July 9?, 1823May 21, 1860) was
a railroad construction foreman now remembered
for his incredible survival of an accident which
drove a large iron rod through his head,
destroying one or both of his frontal lobes.
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Magnetic resonance imaging (MRI), or Nuclear
magnetic resonance imaging (NMRI)
Brain Anatomy and Function