THE CENTRAL NERVOUS SYSTEM (CNS): Brain and Spinal Cord

BRAIN Fun Facts  The brain weighs approximately 3 pounds (1.4 kg)  The brain can send out a message traveling at 289 km/s  It has about 100 billion neurons  Scientists believe there are more neurons in the human brain than there are stars in the Milky Way!

1. BRAINSTEM 1.MIDBRAIN: involved with visual reflexes 2.PONS: controls certain respiratory functions 3.MEDULLA OBLONGATA: regulates heart and lung functions, swallowing, vomiting, coughing, and sneezing

2. CEREBELLUM - coordinates muscle and skeleton movement to maintain posture, balance, and muscle tone

3. CEREBRUM  the largest part of the brain  2 hemispheres: RIGHT and LEFT.  has an outer portion called the “cerebral cortex” (area of conscious decision making)

Lateralization  The fact that certain activities are the almost exclusive domain of one of the 2 hemispheres.  The left hemisphere is geared towards language, math, and logic  The right hemisphere is geared towards musical, artistic and other creative endeavors.  Most individuals with left cerebral dominance are right-handed. (Left-handed people have more right cerebral dominance)

Right or left-brained?

The Stroop test  Right brain – identifies the colour itself  Left brain – reads the colour word  For most people, this is a challenging task, because there is a R-brain/L- brain conflict! Which side to you tend to use for this test?

3. CEREBRUM  Each hemisphere is divided into four lobes  Frontal lobe: controls voluntary motor movements, emotional expression, and moral behavior  Temporal lobe: controls memory, equilibrium, emotion, and hearing  Parietal lobe: controls and interprets the senses and taste  Occipital lobe: controls vision and various forms of expression

Lobes of the cerebrum What is this called? What is the name of this region?

The Story of Phinaeus Gage  Scientists learned a lot about the functions of the frontal lobe due to the bizarre accident that left a young railroad worker by the name of Phinaeus Gage with a severely damaged frontal lobe.

 deep part of the brain  contains the thalamus and the hypothalamus  thalamus: receives, sorts and sends messages from the sense organs (eg. eyes, ears) to cerebral cortex  hypothalamus: controls heart rate, blood pressure, temp. regulation, water and electrolyte balance, digestive functions, and glandular activities 4. DIENCEPHALON

Cerebrospinal Fluid (CSF)  watery fluid that contains various compounds  flows throughout the brain and around the spinal cord  cradles and cushions the brain  also contained in VENTRICLES (cavities) in the brain

Meninges: (from brain to cranium) – pia mater, arachnoid layer, dura mater (PAD) Meninges Meningitis - an inflammation of the meninges -caused by viruses or bacteria -symptoms: fever, headache, and stiff neck -can be fatal

Meninges  dura mater  covers entire length of the spinal cord  contains channels for blood to enter brain tissue  space between dura mater and the bones of the spinal cord is called the “epidural space”  arachnoid membrane  weblike structure that runs across the space containing the cerebrospinal fluid  pia mater  thin membrane containing many blood vessels that nourish the spinal cord

Brain injury  Why do we wear helmets?  A severe concussion can lead to coma

After cocaine use, brain is more active. brain activity Before cocaine use, brain is less active. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Science VU/Visuals Unlimited PET scan (Positron Emission Tomography) -The brain is injected with radioactive glucose -The more active the parts of the brain are, the more glucose is taken up, and the more “blue” the brain areas are -This technique is also used to analyze Alzheimer’s and stroke patients.

Spinal Cord  extends from the base of the brain to the first lumbar vertebra in the lower back  contained within the vertebral column  Vertebral canal – space that contains the spinal column  protected by the vertebral column, the CSF, and by the spinal meninges  Spina bifida  defect in the spinal column in which the spinal cord protrudes outside the vertebrae  Mild cases are visible only by X-ray  Causes varying degrees of paralysis, lack of feeling and movement

Spinal Cord Injuries  if spinal cord is severed, paralysis will occur and affect the area below the injury  Paralysis – loss of movement and sensation  Three common types:  Hemiplegia – paralysis on one side of the body, usually due to a stroke  Paraplegia – paralysis from the waist down, often caused by a car/motorcycle accident, fall, gunshot or stab wound, or sports injury  Quadriplegia – paralysis from the neck down (injury is below the C4 vertebra)