Human Nervous System

Bombick7th Grade ScienceNovember 2010

Outline of PresentationA. Nerve Cell Biology

1. Anatomy2. Physiology

B. Parts of Nervous System1. Brain2. Spinal Cord3. Peripheral Nerves

C. Nervous System Physiology1. Brain Physiology2. Autonomic System

D. Human PsychologyE. Pharmaceuticals and Psychotropic

agents

Nerve Cell Biology

Nerve Cell Physiology•Nerve impulse (think of it as a wave) travels down the axon because ions (sodium and potassium) temporarily travel across the plasma membrane•Nerve impulse at a synapse releases a neurotransmitter from synaptic vesicles•Neurotransmitter crosses the synapse and binds to specific receptors to start another nerve impulse on the other nerve cell•Neurotransmitter that travelled across the synapse is destroyed or reabsorbed by the nerve cell•Large number of drugs and biochemicals interact with this physiological mechanism

Nervous System Anatomy

• Nervous system can be divided into two major components—central and peripheral nervous system

• Central nervous system is comprised of the brain and spinal cord

• Peripheral nervous system is comprised of nerves that come off the brain (cranial) or spinal cord (cervical, thoracic, lumbar, and sacrolumbar)

Brain Anatomy• Brain contains many folds and

convolutions to increase surface area

• Brain can be separated into three principle regions—forebrain, cerebellum, and brain stem

Brain Functions-Brain Stem

• Brain stem is comprised of medulla, pons, and midbrain

• The medulla is the center for respiration, cardiovascular, and digestive functions

• The pons has inhibitory control centers for respiration and interacts with the cerebellum

• The midbrain is involved with the regulation of walking and posture; and of reflexes for head and eye movements

Brain Functions-Cerebellum

• Cerebellum is located behind the brain stem

• Cerebellum is involved in movement coordination

• Involved in the vestibular apparatus

Brain Functions-Forebrain

• Forebrain is comprised of two principle organized regions—a lower diencephalon and a higher telencephalon

• The diencephalon is comprised of the hypothalamus and the thalamus

• The hypothalamus is a homeostatic center controlling body temperature, blood sugar, hunger and satiation, and sexual behavior

• The thalamus is a complex relay station that integrates sensory signals and relays them to the cerebral cortex; also involved in motor control

Brain Functions-Forebrain (cont.)

• The telencephalon of the forebrain contains two nearly symmetrical cerebral hemispheres

• The cerebral hemispheres contain the cerebral cortex, the basal ganglia, and the limbic system

• Each hemisphere is divided into four distinct areas—frontal, parietal, occipital, and temporal

Brain Functions-Forebrain (cont.)

• Frontal lobe is involved in learning, planning, speech, other psychological functions, and some motor functions

• Parietal lobe is involved in some sensory functions (e.g., skin senses); important in certain cognitive and intellectual processes

• Occipital lobe is involved in visual functions

• Temporal lobe is involved in hearing functions and associated speech centers; important involvement in memory

Brain Functions-Forebrain (cont.)

• Basal ganglia helps plan and coordinate gross voluntary movements

• In lower animals the basal ganglia are the highest motor structures

• Limbic system is comprised of the hippocampus, amygdala, cingulate gyrus, and the septum

• Limbic system works with the hypothalamus to control the expression of instinctive behavior, emotions, and drives

• Hippocampus and amygdala also have major cognitive functions, mainly in processing of memory

• Limbic system of mammals are similar indicating similar instinctive behaviors common to all mammals

Simple Anatomy of the Human Brain

Important Note about Brain Function

Even though many functions can be localized to specific regions of the brain, there are many connections via fiber pathways throughout the brain resulting in the brain working as a whole. This is true for the “global functions” of the brain such as learning, memory, and consciousness.

Autonomic Nervous SystemThe autonomic nervous system and the endocrine (hormone) system control the body’s internal organs. It innervates smooth muscle, cardiac muscle, and glands, controlling the circulation of blood, the activity of the gastrointestinal tract, body temperature, and a number of other body functions. Most of this control is not conscious.

Autonomic Nervous System (cont.)

The autonomic nervous system is divided into two parts, the sympathetic and parasympathetic nervous systems, whose actions are mostly antagonistic. Many organs are supplied by nerves from each division, but some are not. The sympathetic nervous system is activated in times of crisis (fight or flight) while the parasympathetic nervous system operates in ordinary times.

Autonomic Nervous System (cont.)

• Autonomic nervous system also stimulates the secretions of the adrenal gland

• The principle secretion of the adrenal gland is epinephrine (adrenalin)

• Epinephrine further effects other parts of organ systems in the autonomic nervous system response (fight or flight)

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Psychopharmacotherapy

• Antipsychotics (Neuropleptics)-Gradually reduce psychotic symptoms such as hallucinations, delusions, paranoia, disordered thinking, and incoherence. Examples include Haldol, Mellaril, Thorazine, and Clozapine

• Antidepressants (Thymoleptics)-Designed to relieve symptoms of depression. Examples include Tofranil, Elavil, Prozac, Anafranil, and Nardil

Psychopharmacotherapy (cont.)

• Antianxiety Drugs (Anxiolytics)-Commonly called tranquilizers, these mood-altering substances are calming, reduce anxiety and stress, and lower excitability. They are the mose widely prescribed of all legal drugs. Examples include Librium, Valium, Xanax, BuSpar, Equanil, Miltown, and Tranxene.

• Antimania Drugs (Lithium)-If taken regulary, lithium carbonate can be effective in preventing both the depression and mania associated with bipolar disorder. Examples include Lithium carbonate and Eskalith.