1. The Spinal Cord, Brain, and Nervous Systems
CTY IBMS

2. I. Nervous System
The chief coordinator of maintaining homeostasis. The nervous system works together and independent of the endocrine system
A. Structural Divisions
1. Central Nervous System (CNS)-includes the brain and spinal cord
2. Peripheral Nervous System (PNS)-all the nerves outside the CNS.
-includes cranial and spinal nerves

3. B. Functional Divisions
1. Somatic Nervous System-controls voluntary functions (those you can control) through skeletal muscles
2. Autonomic Nervous System (ANS)-controls involuntary functions (those you don’t control) through smooth and cardiac muscle and glands

4. -Divided into 2 regions:
a) Sympathetic nervous system-and adrenergic system, as it is activated by adrenaline and noradrenaline
-promotes the “fight or flight” response by increasing heart rate, blood pressure, and blood flow, as well as affecting other areas of the body
b) Parasympathetic nervous system-a cholinergic system, as it is activated by acetylcholine
-balances the sympathetic system and evens the body’s response

5. II. The Spinal Cord A. General Info
-Acts as the link between the PNS and the brain
-Coordinates impulses within the CNS and the brain, acting as the central part of the reflex arc
-Protected by the vertebrae
-Contains unmyelinated tissue (gray matter) surrounded by myelinated tissue (white matter)

6. B. Regions of the spinal cord
-Divided into 4 areas from anterior to posterior:
1) Cervical-covers the first 8 vertebrae (C1-8)
2) Thoracic-covers the next 12 vertebrae (T1-12)
3) Lumbar-covers the next 5 vertebrae (L1-5)
4) Sacral-covers the last 5 vertebrae (S1-5)
-Sensory impulses are carried up toward the brain through pathways known as ascending tracts
-Motor impulses traveling from the brain are carried in descending tracts to the PNS

7. III. The Brain
The Brain is a large organ composed of a mass of interneuron's located in the cranial cavity.
The Brain is highly specialized and subdivided into three major regions: The Cerebrum, Cerebellum, and Medulla

9. 1. Cerebrum – largest portion of the brain regulates conscious thought, memory, sense interpretation, reasoning, and other voluntary activities.
2. Cerebellum – located at the rear of cranium.
Responsible for coordinating muscular activities and balance (cerebalance).
3. Medulla – Located at the base of brain. Regulates the automatic, rhythmic processes of the body
Ex. Heart beat, Peristalsis, Rate of breathing, etc.

10. IV. CNS Protection
-The brain and spinal cord are water based tissues and are very delicate structures.
-Their protection is of vital importance to the health and well being of an organism.
-Besides the vertebrae, other forms of protection include:
1)Meninges-3 layers of connective tissue that surround the brain and spinal cord.
-The layers include:
a) Dura mater-outermost, thickest, toughest layer
b) Arachnoid-middle layer
c) Pia mater-softest, innermost layer

11. 2) Cerebrospinal Fluid (CSF)-a clear liquid that circulates in and around the brain and spinal cord.
-Provides a cushion and protects from shock
-Also carries nutrients and picks up waste
-These structures, along with CNS neurons and capillaries create the blood-brain barrier, which effectively protects the CNS from most harmful substances

12. V. Nervous System Disorders
A. Spinal Cord Disorders
1) Multiple Sclerosis-myelin sheath around neuron axons is damaged.
-affects both brain and spinal cord
-impulse conduction is slowed and messages misinterpreted
-an autoimmune disorder, it affects young people, especially women
-no cure, but treatments are available

13. 2) Amyotrophic lateral sclerosis (Lou Gehrig’s disease)- motor neurons are progressively destroyed
-may take months to years, but eventually death takes place
-no treatments or cures
3) Poliomyelitis (Polio)-a viral disease of children, causes motor neuron destruction
-almost eradicated by vaccines
4) Cancer of the nervous system-difficult to treat because of delicacy of organs involved

14. 5) Spinal cord injuries-caused by wounds, fractures, or dislocation due to falls, sports, or car accidents.
-The suffix “plegia” is used to describe the nature of the injury (paraplegia, quadriplegia, etc)
6) Neural poisons-take the place of neurotransmitters and can cause death.
-Examples include strychnine, curare, botulin toxin among others

15. B. Brain disorders
1) Encephalitis-inflammation of the brain
-caused by viruses and other infections
2) Hydrocephalus-too much CSF within the brain
-more common in infants
-a shunt is used to drain the excess fluid
3) Epilepsy-abnormal brain electrical activity
-seizures are common in this chronic condition
-very treatable

16. 4) Hematomas-trauma which causes bleeding in and around the meninges
5) Concussion-a blow to the head or sudden movement where the brain hits the skull
6) Alzheimer’s disease-unexplained degeneration of the cerebral cortex and hippocampus
-no cure, but the disease can be slowed
7) Dementia-loss of brain function from a number of causes
8) Parkinson’s disease-cell death in parts of the brain leads to a host of neurological problems
-hard to treat due to the blood-brain barrier