Chapter 8

Central Nervous System

Edited by Dr. Ryan Lambert-Bellacov

CNS Functions

• CNS stands for central nervous system

• Communication and coordination system in the body

• Gives us personality

• Seat of intellect and reasoning

Edited by Dr. Ryan Lambert-Bellacov

The Nerve Cell

• Called the neuron

• Nucleus, cytoplasm, and cell membrane

• Dendrites – received the signal

• Axons (only one per cell)– myelin sheath (how it conducts the signal

Nervous Tissue/Cells

• Neurons (different types)– Sensory = afferent

– Motor or efferent

– Associative or interneurons

• Membrane excitability

Synapse

• When messages go from one cell to the next cell

• Synaptic cleft

• Neurotransmitters

Edited by Dr. Ryan Lambert-Bellacov

Divisions of the Nervous System

• Central nervous system– Brain

– Spinal cord

• Peripheral nervous system– 12 pairs of cranial nerves (coming out of the brain)

– Eyes, smell, ect…

– 31 pairs of spinal nerves

– Autonomic nervous system (fight or flight

Edited by Dr. Ryan Lambert-Bellacov

Effects of Aging

• Slowing nerve conduction

• Loss of brain size

• Slowing of reaction time

• Changes in sleep patterns

The Brain

• Weighs about 1400 grams or 3 pounds

• 100 billion neurons

• Meninges (covering) and cerebrospinal fluid

• Without oxygen, brain damage occurs within 4-8 minutes

Edited by Dr. Ryan Lambert-Bellacov

The Brain

• Cerebrum

• Diencephalon

• Cerebellum

• Brain stem

The Brain

Memory

• Storage of old and new information

• Role of the hippocampus

• Short or long term memory

Meninges =Coverings of the Brain

• Dura mater

• Arachnoid mater

• Pia mater

Edited by Dr. Ryan Lambert-Bellacov

Ventricles of the Brain• Four lined cavities filled with cerebrospinal

fluid• 1st and 2nd

– Right and left lateral ventricles

• 3rd

– Connected to the lateral ventricles by the interventricular foramen

Ventricles of the Brain

• 4th

– Connected to the 3rd by the cerebral aqueduct

Edited by Dr. Ryan Lambert-Bellacov

CSF

• Cerebral spinal fluid =CSF

• Formed inside the four ventricles

• Formation and flow of CSF (cerebrospinal fluid)

• Blood-brain barrier

• Lumbar puncture

Cerebrum

• Largest part of the brain

• Weighs about 2 pounds

• Cerebral cortex

• Two hemispheres and longitudinal fissure

• Fissures and sulci

• Gyri or convulutions

Edited by Dr. Ryan Lambert-Bellacov

Five Major Fissures

• Longitudinal fissure• Transverse fissure• Central fissure• Lateral fissure• Parieto-occipital fissure

Edited by Dr. Ryan Lambert-Bellacov

Cerebral Functionsdepends on location

• Frontal lobe

• Parietal lobe

• Occipital lobe

• Temporal lobe

• Limbic lobe or system

Edited by Dr. Ryan Lambert-Bellacov

Diencephalon

• Located between the cerebrum and the midbrain

• Thalamus

• Hypothalamus

Hypothalamus

• Important part of homeostasis

• Autonomic nervous control

• Cardiovascular control

• Temperature control

• Appetite control

• Water balance

Hypothalamus

• Manufacture of oxytocin

• Gastrointestinal control

• Emotional state

• Sleep control

• Mind-over-body experiences

Cerebellum

• Located behind the pons and below the cerebrum

Cerebellar Function

• Located behind the pons and below the cerebrum

• Maintenance of balance

• Maintenance of muscle tone

• Coordination of muscle movements

Brain Stem

• Midbrain

• Pons -breathing

• Medulla oblongata

• The cranial nerves 3-12 emerge

Spinal Cord

• Begins at foramen magnum of the occipital bone

• Ends at the second lumbar vertebrae

• 31 pairs of spinal nerves

• Protected by meninges and other tissues

• White and gray matter

• Functions

• gray horns and the gray commissure form the “gray H.”

Columns” of white matter carry information either up or down the spinal cord

Blood Brain BarrierBlood Brain Barrier

Slide 7.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Includes the least permeable capillaries of the body

Excludes many potentially harmful substances

Useless against some substances Fats and fat soluble molecules Respiratory gases Alcohol Nicotine Anesthesia

Traumatic Brain Injuries (TBI)Traumatic Brain Injuries (TBI)

Slide 7.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Concussion Slight or mild brain injury Bleeding & tearing of nerve fibers

happened Recovery likely with some memory loss

Contusion A more severe TBI Nervous tissue destruction occurs Nervous tissue does not regenerate

Cerebral edema Swelling from the inflammatory response May compress and kill brain tissue

• Cerebral edema– Swelling from the inflammatory response

– May compress and kill brain tissue

• Subdural hematoma– Collection of blood below the dura

• Standards for these conditions were revised in 2004. Please check out TBIs at Mayoclinic.com for more current information on diagnostic terminology.

Cerebrovascular Accident (CVA)Cerebrovascular Accident (CVA)

Slide 7.50Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Commonly called a stroke

The result of a ruptured blood vessel supplying a region of the brain

Brain tissue supplied with oxygen from that blood source dies

Loss of some functions or death may result

Alzheimer’s DiseaseAlzheimer’s Disease

Slide 7.51Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Progressive degenerative brain disease

Mostly seen in the elderly, but may begin in middle age

Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons

Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death

Disorders

• Meningitis

• Encephalitis

• Epilepsy

• Cerebral palsy

Disorders

• Poliomyelitis

• Hydrocephalus

• Parkinson’s disease

• Essential tremor

Disorders

• Multiple sclerosis

• West Nile virus

• Dementia

• Alzheimer’s disease

Disorders

• Brain tumors

• Hematoma

• Spinal cord injuries– Quadriplegia

– Paraplegia

Headaches

• Tension

• Migraine

• Cluster