Neurotransmitters(How it works?)

By:Pamela M. Veroy, RN, MAN

Is your brain this size?

ANATOMY & PHYSIOLOGYNERVOUS SYSTEM (NS)

• CENTRAL NS– BRAIN & SPINAL CORD

• PERIPHERAL NS– CRANIAL & SPINAL NERVES

• AUTONOMIC– SYMPATHETIC - THORACO- LUMBAR– PARASYMPATHETIC – S2,3,4

ANATOMY & PHYSIOLOGY

BRAIN:

• CEREBRUM

• DIENCEPHALON

• BRAIN STEM

• CEREBELLUM

ANATOMY & PHYSIOLOGY

CEREBRUM

• HEMISPHERES

• LOBES

• CORPUS CALLOSUM

• BASAL GANGLIA

• FRONTAL

• PARIETAL

• TEMPORAL

• OCCIPITAL

ANATOMY & PHYSIOLOGY

FRONTAL LOBE:• PERSONALITY, BEHAVIOR• HIGHER INTELLECTUAL FUNCTIONING• PRECENTRAL GYRUS: MOTOR FXN• BROCA’S AREA – MOTOR SPEECH

WERNICKE’S AREA OF TEMPORAL: SENSORY SPEECH

PARIETAL LOBE:POST CENTRAL GYRUS : GENERAL SENSATIONINTEGRATES SENSORY INFO

BROO---M

ANATOMY & PHYSIOLOGY

TEMPORAL LOBE• HEARING, TASTE & SMELL• WERNICKE’S AREA – SENSORY SPEECH

BROCA’S AREA OF FRONTAL LOBE – MOTOR SPEECH

OCCIPITAL LOBE

VISION

BASAL GANGLIA

REGULATE & INTEGRATE MOTOR ACTIVITY

PART OF EPS

ANATOMY & PHYSIOLOGY

DIENCEPHALON• THALAMUS• HYPOTHALAMUS

BRAINS STEMMIDBRAIN, PONS, MEDULLANUCLEI OF CN’s - 12VITAL CENTERS OF: REPIRATORY, VASOMOTOR & CARDIAC FXNSCEREBELLUMMUSCLE TONE & EQUILIBRIUM

PRIMITIVE EMOTIONS: RAGE & FEAR

CONTROL CENTER FOR PITUITARYREGULATION OF VITAL FXN : BP, SLEEP, FOOD INTAKE, BODY TEMP

ANATOMY & PHYSIOLOGY

SPINAL CORD

• GRAY MATER – H SHAPED– INTERIOR

• WHITE MATER – EXTERIOR

• CENTER OF REFLEX ACTIONS

• 31 SEGMENTS : – 8 CERVICAL– 12 THORACIC – 5 LUMBAR – 5 SACRAL– 1 COCCYGEAL

ANATOMY & PHYSIOLOGY

MENINGES

• SEROUS MEMBRANE OF CRANIOSPINAL CAVITY

• 3 LAYERS:– DURA– ARACHNOID– PIA

-CS FLUID

ANATOMY & PHYSIOLOGY

NERVES

• FIBERS WHICH EXTEND BEYOND CNS

• NEURON

-BASIC UNIT

REFLEX ARC

BASIC FXNAL UNIT OF N.S.

SENSORY/MOTORMIXEDPERIPHERAL

Neurotransmitters• Approximately 100 billion brain cells form groups

of neurons, or nerve cells that are arranged in networks.

• These neurons communicate information with each other by sending electrochemical messages from neuron to neuron, a process called neurotransmission

• These electrochemical messages pass from the dendrites (projections from the cell body), through the cell body, down the axon (long, extended structures), and across the gaps between cells (synapse) to the dendrite of the next neuron.

• In the nervous system, the electrochemical cross the gaps or synapse between neural cells by way of special chemical messenger called neurotransmitters.

• Neurotransmitters are the chemical substances manufactured in the neuron that aid in the transmission of information throughout the body.

• They either excite or stimulate an action in the cells (excitatory) or inhibit or stop an action (inhibitory).

• These neurotransmitters fit into specific receptor cells embedded in the membrane of the dendrite, just like a certain key shape fits into a lock.

• After neurotransmitters are released into the synapse and relay the message to the receptor cells, they are either transported back from the synapse to the axon to be stored for later used (reuptake) or are metabolized and inactive by enzymes, primarily monoamine oxidase (MAO) (Lewis 2000)

The Neurotransmitters

• Major transmitters have been found to play a role in psychiatric illnesses are well an actions and side effects of psychotropic drugs.

• Dopamine and serotonin have received the most attention in terms of the study and treatment of psychiatric disorders (Tecott, 2000).

• These neurotransmitters are necessary in just the right proportions to relay messages across the synapse.

• Studies are beginning to show that there is a difference in the amount of some neurotransmitters available in the brain of persons with certain mental disorders compared with persons with no signs of mental illness.

• The following is a discussion of the major neurotransmitters that have been associated with mental disorders.

Type of transmitter

Mechanism of action

Physiologic effects

Dopamine Excitatory Controls complex movements, motivation, cognition; regulates emotional response

Norepinephrine(noradrenaline)

Excitatory Changes in attention, learning and memory, sleep and wakefulness, mood

Type of transmitter Mechanism of action

Physiologic effects

Epinephrine (Adrenaline)

Excitatory Fight-or-flight response

Serotonin Inhibitory Control of food intake, sleep and wakefulness, temperature regulation, pain control, sexual behaviors, regulation of motions

Histamine Neuromodulator

Alertness, control of gastric secretions, cardiac stimulation, peripheral allergic response

Acetylcholine Excitatory or inhibitory

Sleep and wakefulness cycle; signals muscles to become alert

Type of transmitter

Mechanism of action

Physiologic effects

Neuropeptides Neuromodulators

Enhance, prolong, inhibit, or limit the effects of principal neurotransmitters

GlutamateGamma-amino butyric acid (GABA)

Excitatory Neurotoxicity results if levels are too highModulates other neurotransmitters

• Histamine

• The role of histamine in mental illness is under investigation.

• It is involved in producing peripheral allergic responses, control of gastric secretions, cardiac stimulation, and alertness.

• Some psychotropic drugs block histamine, resulting in weight gain, sedation, and hypotension.

• Acetylcholine• Acetylcholine is a neurotransmitter found in the brain,

spinal cord, and peripheral nervous system, particularly at the neuromuscular junction of skeletal muscle.

• It can be excitatory or inhibitory. It is synthesized from dietary choline found in red meat and vegetables and has been found to affect the sleep/wake cycle and signals muscles to become active.

• Studies have shown that persons with Alzheimer’s disease have a decreased number of acetylcholine-secreting neurons

• Persons with myasthenia gravis (a muscular disorder in which impulses fail to pass the myoneural junction, causing muscle weakness) have a reduced number of acetylcholine receptors.

• Gamma-amino butyric Acid (GABA)• GABA, an amino acid, is the major inhibitory

neurotransmitter in the brain and has been found to modulate other transmitter systems rather than providing a direct

• Drugs that increase GABA function, such as benzodiazepines, are used to treat anxiety and induce sleep.

• Glutamate is an excitatory amino acid that at high levels can have major neuro-toxic effects.

• Glutamate has been implicated in the brain damage caused by stroke, hypoglycemia, sustained hypoxia or ischemia, and some degenerative diseases such as Huntington’s or Alzheimer’s disease.

Brain Imaging TechnologyProcedure Imaging Method Results DurationComputed tomography(CT) Magnetic resonance imaging

Serial X-rays of brainRadio waves from brain detected from magnet

Structural ImageStructural Image

20-4 minutes45 minutes

Position emission tomography (PET)

Radioactive tracer injected into bloodstream and monitored as client perform activities

Functional 2-3 hours

Procedure Imaging Method Results Duration

Single photon emission computed tomography (SPECT)

Same as PET Functional 1-2 hours

Limitations of brain Imaging techniques• The use of radioactive substances in PET and

SPECT limits the number of time as person can undergo these tests.

• There is the risk that the client will have an allergic reaction to the substances.

• Some clients may find receiving intravenous does of radioactive material frightening or unacceptable.

• Imaging equipment is expensive to purchase and maintain, so availability can be limited. A PET camera cost about $2.5 million; a SPECT camera cost about $ 500,000.

• Some person cannot tolerate these procedures because of fear or claustrophobia.

• Researchers are finding that many of the changes that occur in disorders such as schizophrenia are at the molecular and chemical level and cannot be detected with current imaging techniques.

• Find as many as you can the neurotransmitters in the word puzzle box.

• Clue- there are 19.

Answers