NERVOUS SYSTEM & BEHAVIORAL DISORDERS

nervous system and the endocrine system

coordinate and control the body.

homeostasis

they regulate our responses to the environment and maintain

hormones

Endocrine system functions by means of .

impulses

Nervous system functions by means of electric

Central nervous system (CNS)

Peripheral nervous system (PNS)

Nervous system are divided into two:

Central nervous system (CNS)

Consisting of the brain and spinal cord.

Somatic nervous system

Visceral or autonomic nervous system (ANS)

Functionally, nervous system are divided into:

Peripheral nervous system (PNS)

Consisting of all nervous tissue outside the brain and spinal cord.

Somatic nervous system

Controls skeletal muscles

Visceral or autonomic nervous system (ANS)

-Controls smooth muscle, cardiac muscle, and glands.

-ANS regulates responses to stress and helps maintain homeostasis.

Neurons, or nerve cells

Neuroglia

Two types of cells in the nervous system:

Neurons, or nerve cells

Make up the conducting tissue of the nervous system.

Neuroglia

The connective tissue cells of the nervous system that support and protect nervous tissue.

neuron

is the basic functional unit of the nervous system.

Dendrite

Axon

Each neuron has two types of fibers extending from the cell body:

Dendrite

Carries impulses toward the cell body.

Axon

Carries impulses away from the cell body.

myelin

Some axons are covered with ?

●A whitish, fatty material that insulates and protects the axon and speeds electric conduction.

myelinated

Covered axons are called ?, makes up the white matter of the nervous system.

unmyelinated tissue

Uncovered axonx are called ?, makes up the gray matter of the nervous system.

Sensory neuron

Motor neuron

Each neuron is part of a relay system that carries information through the nervous system.

Sensory neuron

that transmits impulses toward the CNS.

Motor neuron

that transmits impulses away from the CNS

Synapse

There are also connecting neurons within the CNS.

Synapse

●The point of contact between two nerve cells.

●At the ?, energy is passed from one cell to another by means of a chemical neurotransmitter.

nerves

Cable-like bundles of fibers (axons) that transmit electrochemical signals between the central nervous system (brain and spinal cord) and the rest of the body.

●Individual neuron fibers are held together by ?.

ganglion

A collection of cell bodies along the pathway of a nerve is a ?.

sensory nerves

● A few nerves ? contain only sensory neurons..

motor nerves

●A few ? contain only motor neurons.  

mixed nerves

Most contain both types of fibers and described as

Cerebrum

The largest part of the brain.

cerebral cortex

Composed largely of white matter with thin outer layer of gray matter, the

cortex

Within the ?, the higher brain functions of memory, reasoning, and abstract occur.

longitudinal fissure.

The cerebrum is divided into two hemispheres by a deep groove

lobes

Each hemisphere is further divided into ? with specialized functions.

Diencephalon

Contains the following:

Thalamus

Hypothalamus

Pituitary gland

 

Thalamus

receives sensory information and directs it to the proper portion of the cortex.

Brainstem

consists of the following:

Midbrain, midbrain

Pons

Brain

Medulla oblongata

Hypothalamus

controls the pituitaryand forms a link between the endocrine and nervous systems.

Autism

• A complex disorder of unknown cause that usually appears before age 3.

• It is marked by selfabsorption and lack of response to social contact and affection.

Schizophrenia

●Form of chronic psychosis that may include bizarre behavior, paranoia, anxiety, delusions, withdrawal, and suicidal tendencies.

Bipolar disorder (formerly called manic depressive illness)

●Characterized by depression with episodes of mania, a state of elation, which may include agitation, hyper excitability, or hyperactivity.

Dysthymia

●A mild form of depression triggered by a serious event

●Lasts for several months to years.

Depression

A mental state characterized by profound feelings of sadness, emptiness, hopelessness, and lack of interest or pleasure in activities, often accompanied by suicidal tendencies.

Attention deficit-hyperactivity disorder (ADHD)

• Difficult to diagnose because many symptoms overlap or coexist with other behavioral disorders.

• Commonly begins in childhood and characterized by attention problems, easy boredom, impulsive behavior, and hyperactivity.

• Correlated with alterations from the norm in brain structure and metabolism.

• Treated with stimulant drugs, primarily methylphenidate (Ritalin).

Obsessive-compulsive disorder (OCD)

●A condition marked by recurrent thoughts or images that are persistent and intrusive.

Phobia

●An extreme, persistent fear of a specific object or situation.

●It may center on social situations; particular objects, such as animals or blood; or activities, such as flying or driving through tunnels.

Panic disorder  

●A form of anxiety disorder marked by episodes of intense fear.

●A person with ? may isolate himself or herself or avoid social situations for fear of having a panic attack or in response to attacks

Generalized anxiety disorder (GAD)

●Characterized by chronic excessive and uncontrollable worry about various life circumstances, often with no basis.

●May be accompanied by muscle tensing, restlessness, dyspnea, palpitations, insomnia, irritability, or fatigue.

Anxiety

●Feeling of fear, worry, uneasiness, or dread.

●May be associated with physical problems or drugs and often prompted by feelings of helplessness or loss of self-esteem.

NREM

sleep is interrupted about every 1.5 hours by episodes of rapid eye movement

REM

sleep, during which the eyes move rapidly, although they are closed

Sleep apnea

• Refers to failure to breathe for brief periods during sleep.

• Usually results from upper airway obstruction due to:

• Obesity

• Alcohol consumption

• Weakened throat muscles

• Usually accompanied by loud snoring with brief periods of silence.

• Treatment:

• Dental appliances that move the tongue and jaw forward to prevent sleep apnea.

• Surgery to correct obstruction or positive air pressure delivered through a mask.

Narcolepsy

• Characterized by brief, uncontrollable attacks of sleep during the day.

• Treatment: stimulants, regulation of sleep habits, and short daytime naps.

Insomnia

• Refers to insufficient or non-restorative sleep despite ample opportunity to sleep.

• Often it is related to emotional upset caused by stressful events.

Epilepsy

• Recurrent seizures brought by abnormal electric activity of the brain.

• The attacks vary from:

• Brief and mild episodes known as absence (petit mal) seizures

• Major tonicclonic (grand mal) seizures with loss of consciousness, convulsion (intervals of violent involuntary muscle contractions), and sensory disturbances.

• In other cases (psychomotor seizures), there is 1- to 2-minute period of disorientation.

Multi-infarct dementia (MID)

• Resembles AD.

• A progressive cognitive impairment associated with:

• Loss of memory

• Loss of judgment

• Aphasia

• Altered motor and sensory function

• Repetitive behavior

• Loss of social skills

• The disorder is caused by multiple small strokes that interrupt blood flow to brain tissue and deprive areas of oxygen

Alzheimer disease (AD)

• Results from unexplained degeneration of neurons and atrophy of the cerebral cortex.

• The changes cause progressive loss of recent memory, confusion, and mood changes.

Parkinson disease

• Occurs with unknown reasons

• Certain neurons in the midbrain fail to secrete the neurotransmitter dopamine.

• Symptoms:

• Tremors

• Muscle rigidity

• Flexion at the joints

• Akinesia (loss of movement)

• Emotional problems

• Treatment

• Daily administration of drug L-dopa (levodopa)

• A form of dopamine that can be carried by the blood into the brain.

Multiple sclerosis (MS)

• Commonly attacks people in their 20s or 30s and progresses at intervals and varying rates.

• It involves patchy loss of myelin with hardening (sclerosis) of tissue in the CNS.

• Symptoms:

• Vision problems

• Tingling or numbness in the arms and legs

• Urinary incontinence

• Tremor

• Stiff gait

• Exact cause is not known.

Meningioma

• Is a tumor of the meninges.

• Does not spread and is localized at the surface, it can be completely removed by surgery.

Gliomas

• Tumors that originates in the neuroglia.

• Named according to the specific type of cell involved such as:

• Astrocytoma

• Oligodendroglioma

• Schwannoma (neurilemoma)

• Described as benign, because they tend not to metastasize.

• Can harm by compressing brain tissue.

Neuroglia

• Non-conducting support cells.

• Where most of the tumors of the nervous system originates.

Shingles

• Infection
  that spreads along peripheral nerves, causing
  lesions and inflammation.

• Causes: Herpes zoster, chickenpox virus

Aseptic meningitis

• Benign, non-bacterial form meningitis caused by a virus.

Meningitis

• Inflammation of the meninges.

• Usually caused by bacteria that enter through the ear, nose, or throat or are carried by the blood.

• Organisms causes meningitis:

• Meningococcus

meningitidis),

responsible for

epidemics of meningitis among individuals living in close quarters.

• Haemophilus influenzae

• Streptococcus pneumoniae

• Escherichia coli

• Common symptom: Stiff neck

Contrecoup injury

• Damage that occurs on the side of the brain opposite the blow as the brain is thrown against the skull.

Cerebral concussion

• Results from a blow to the head or from fall.

• Symptoms

• Headache

• Dizziness

• Vomiting

• Loss of consciousness

• Paralysis

Subdural hematoma

• Results from a blow in the front or back of the head.

• The force of the blow separates the dura from the membrane below the arachnoid.

• Blood from a damaged vessel, usually a vein, slowly enters this space.

• The gradual accumulation of blood puts pressure on the brain,

• Symptoms:
  headache weakness dementia

• Continued bleeding, death results.

Epidural hematoma

• Caused by damage to artery from a skull fracture, usually on the side of the head.

• Appears between the dura mater and the skull bone.

Hematoma

• Bleeding into or around meninges caused from a blow to the head.

Hemiplegia

• Paralysis of one side of the body

• Can be seen also on the side opposite the damage.

• Immediate retraining therapy may help to restore lost function.

Aphasia

• Loss or impairment of speech communication.

• Common aftereffect.

Aneurysm

• A localized dilation of a vessel that may rupture and cause hemorrhage.

• ? can be congenital or may arise from
  other causes, especially atherosclerosis, which weakens the vessel wall.

• Hypertension contributes to its rupture.

• The effects of cerebral hemorrhage vary from massive loss of function to mild impairment of sensory or motor activity, depending on the degree of damage.

Embolism

• Sudden blockage by an obstruction traveling from another part of the body.

• In cases of stroke, the embolus usually originates in the heart.

• Methods to diagnosed the obstructions:

• Cerebral angiography with radiopaque dye.

• Computed tomography (CT) scans

• Other radiographic techniques

Thrombosis

• Formation of a blood clot in a vessel.

• Mostly, in cases of CVA, thrombosis occurs in the carotid artery,

• The large vessel in the neck that supplies the brain.

• Treatment:

• Removal of the vessel that is blocked and insert a graft.

• Carotid endarterectomy to open the vessel, if the carotid artery leading to the brain is involved .

• Drugs for dissolving ("busting") such clots are now available.

Cerebrovascular Accident (CVA) or stroke

• Applies to any occurrence that deprives brain tissue of oxygen.

• These includes:

• Blockage in a vessel that supplies the brain

• Ruptured blood vessel

• Other damage that leads to hemorrhage within the brain.

• Third leading cause of death in developed countries, after cancer and heart attack (myocardial infarction).

• Leading cause of neurologic disability.

Autonomic Nervous System

• The division of the nervous system that controls the involuntary actions of
  muscles and glands.

• Sympathetic nervous system

• Parasympathetic nervous system.

• Two divisions of Autonomic Nervous System:

Sympathetic nervous system

Motivates response to stress the

SO-called "fight-or-flight" response.

• It increases heart rate and respiration rate, stimulates the adrenal gland, and delivers more blood to skeletal muscles.

Autonomic Nervous System

• Parasympathetic nervous system.

• Returns the body to a steady state and stimulates maintenance activities, such as digestion of food.

• Most organs are controlled by both systems and the two systems have opposite effects on a given organ.

Spinal Cord

• The spinal cord extends from the medulla oblongata to between the first and second lumbar vertebrae.

• The central area consist of gray matter surrounded by white matter.

• The gray matter projects toward the back (dorsal) and the front as the dorsal and ventral horns.

• The white matter contains the ascending and descending tracts (fiber bundles) that carry impulses to and from the brain.

Dorsal, or posterior root

• Carries sensory impulses into the cord;

Ventral, or anterior root

• Carries motor impulses away from the cord and out toward a muscle or gland.

brain

• Within the brain are four ventricles (cavities) in which cerebrospinal fluid (CSF) is produced.

• The fluid circulates around the brain and spinal cord, acting as a protective cushion for these tissues.

• Covering the ? and the spinal cord are three protective layers called the meninges.

• Dura mater

• Outermost and toughest layer.

• Arachnoid

• Middle layer

• Pia mater

• Thin, vascular inner layer, attached directly to the tissue of the brain and spinal cord