Chapter V: Nervous System

Nervous System

A body system that coordinates all body functions, enabling a person to adapt to internal or external environments.

• Neurons

• Neuroglia

(2) Types of Nervous Cells

Neurons

The conducting cells in the nervous system.

Neuroglia

The supportive cells in the nervous system.

Dendrites

A short branched extension of the nerve cell.

Axon

A long thin cable-like extension of a neuron that carries electrical impulses away from the neuron’s cell body.

Myelin Sheath

A fatty, insulating layer that wraps around the neuron’s axon to allow electrical impulses to travel faster; people with paralysis typically have these parts damaged.

Synapse

A special site where nerve cells communicate with other nerve cells and body cells.

Sensory Input

Integration

Motor Output

(3) Functions of the Nervous System

Sensory Input

A function of the nervous system that gathers information and monitors changes inside and out the body.

Integration

A function of the nervous system that interprets the received sensory signals and decide that action needed.

Motor Output

A function of the nervous system that responds to the integrated stimulus and activates muscles or glands.

Brain

Main organ for integrating information.

• Central Nervous System

• Peripheral Nervous System

(2) Structural Classification of Nervous System

Central Nervous System

A structural classification of nervous system that comprises the brain and spinal cord.

Peripheral Nervous System

A structural classification of nervous system that comprises of nerves outside the brain and spinal cord, such as spinal nerves (C1—S5) and cranial nerves (I—XII).

Sensory (Afferent) Division

A functional classification of nervous system that picks up sensory stimuli.

Motor (Efferent) Division

A functional classification of the nervous system that sends directions from your brain to the muscles and glands.

Somatic Nervous System

A functional classification of the nervous system that is voluntary; rules your skeletal movement.

Autonomic Nervous System

A functional classification of the nervous system that is involuntary; keeps your heart beating, stomach churning, and etc.

Sympathetic Division

A functional classification of nervous system that prepares your body for tense physical activity and stress; fight or flight response.

Norepinephrine

A chemical that the sympathetic nervous system releases as a neurotransmitter to speed up activity.

Parasympathetic Division

A functional classification of nervous system that returns the body to a relaxed and balanced state; rest and digest response.

Acetylcholine

A chemical that the parasympathetic nervous system releases as a neurotransmitter to slow down activity.

Cerebral Hemispheres (Cerebrum)

Diencephalon

Brain Stem

Cerebellum

(4) Regions of the Brain

Cerebrum

The region of the brain that is half the mass and the largest part of the human brain; paired to the left and right superior parts of the brain.

Cerebral Cortex

The wrinkled layer of the brain composed of tightly packed nerve cells.

• Gray Matter

• White Matter

(2) Components of the Cerebral Cortex

Gyri

Bumps on the surface of the brain’s cerebral cortex

Sulci

Grooves or depressions on the surface of the brain’s cerebral cortex that separate the folds.

Fissures

Deep grooves that divide the cerebrum into lobes.

• Frontal Lobe

• Parietal Lobe

• Occipital Lobe

• Temporal Lobe

(4) Surface Lobes of the Cerebrum

Frontal Lobe

A lobe of the brain that is associated with reasoning, planning, parts of speech, movement, emotions, and problem solving.

Parietal Lobe

A lobe associated with orientation, recognition, and perception of stimuli.

Temporal Lobe

A lobe associated with perception and recognition of auditory and olfactory stimuli, memory, emotional expression, and speech.

Occipital Lobe

A lobe associated with visual processing and assist in language generation; depth perception.

Broca’s Area

A region in the frontal lobe that is linked to speech production.

Broca’s Aphasia

A language disorder that causes people to struggle forming words or sentences, resulting in speech that is slow.

Wernicke’s Area

An area in the temporal lobe that is linked to comprehension of speech.

Wernicke’s Aphasia

A language disorder that impairs a person’s ability to understand spoken and written language.

• Somatic Sensory Area

• Primary Motor Area

• Broca’s Area

• Wernicke’s Area

(4) Specialized Area of the Cerebrum

Somatic Sensory Area

A specialized area of the cerebrum that receives impulses from the body’s sensory receptors.

Primary Motor Area

A specialized area in the cerebrum that sends impulses to the skeletal muscle.

• Gustatory Area

• Visual Area

• Auditory Area

• Olfactory Area

(4) Specialized Cerebral Areas Involved in Special Senses

• Speech Region

• Language Comprehension Region

• General Interpretation Area

(3) Specialized Cerebral Areas Involved in Interpretation

Gray Matter

The outer layer of the cerebrum, a site for processing sensation, perception, voluntary movement, learning, and speech.

White Matter

Provides communication between the gray matter to the different parts of the body; a fiber tract inside the outer matter.

Basal Ganglia

Internal islands of gray matter; responsible for motor control.

Diencephalon

A region of the brain that sits on top of the brain stem and enclosed by the cerebrum.

• Thalamus

• Hypothalamus

• Epithalamus

(3) Parts of the Diencephalon

Thalamus

A part of the diencephalon that surrounds the third ventricle; the relay station of sensory and motor impulses to the correct pair of cortex for localization and interpretation.

Hypothalamus

A part of the diencephalon that is under the thalamus and is a crucial autonomic nervous system center; regulates.

Epithalamus

A part of the diencephalon that forms the roof of the third ventricle and houses the pineal body and the choroid plexus; links the nervous system to the endocrine system.

Pineal Body

A small cone-shaped endocrine gland located inside the epithalamus that secretes the hormone melatonin into the bloodstream; situated beneath the back part of the corpus callosum.

Choroid Plexus

A network of blood vessels in the brain that produces cerebrospinal fluid; also found in the epithalamus.

Brain Stem

A region of the brain that attaches to the spinal cord, also considered as the lowest part of the brain; controls the flow of messages and is responsible for basic vital life functions like heartbeat.

• Midbrain

• Pons

• Medulla Oblongata

(3) Parts of the Brain Stem

Midbrain

A part of the brain stem that is mostly composed of tracts of nerve fibers and the reflex center for vision and hearing.

Peduncles

A part resembling a stalk in shape or function.

Cerebral Peduncles

The two bulging fiber tracts found in the midbrain.

Corpora Quadrigemina

The four rounded protrusions of the midbrain.

Pons

A part of the brain stem that relays messages from the cortex to the cerebellum; responsible for facial sensitivity and plays a major role in REM.

Medulla Oblongata

A part of the brain stem breathing, heart rate, digestion and sleeping; also responsible with initiating reflex like gagging or vomiting.

Limbic System

A complex network of brain structures involved in emotion, memory, and motivation; plays a key role in processing emotional responses.

Amygdala

A component of the limbic system, is responsible for processing fear and emotional memories.

Hippocampus

A component of the limbic system that is essential in forming and recalling memories.

Rapid Eye Movement

A form of deep sleep and is also the stage where dreams occur, brought upon by the amygdala and the hippocampus.

Reticular Activating System

A diffused mass of gray matter along the brain stem, involved in the motor control of visceral organs; also plays a role in sleep cycle and consciousness

Circadian Rhythm

A term that refers to the pattern of rest and sleep.

Cerebellum

A region in the brain that is responsible for coordinating voluntary movement, balance, posture, and muscle tone.

• 2 Internal Carotid Arteries

• 2 Vertebral Arteries

(4) Major Arteries Oxygenating the Brain

Basilar Artery

The artery when two vertebral arteries join together at the base of the skull.

Electroencephalogram

A medical test used to detect and record the electrical activity of the brain.

Circle of Willis

An anastomosis at the base of the brain, continually circulating blood to the brain.

• Meninges

• Cerebrospinal Fluid

• Blood-brain Barrier

(3) Protective Layers of the Central Nervous System

• Dura Mater

• Arachnoid Mater

• Pia Mater

(3) Layers of the Meninges

Dura Mater

The outer layer of the meninges, that provides protection from direct infection and fold inwards.

Arachnoid Mater

The middle layer of the meninges that is structured like a spider’s web and cushions the central nervous system; circulates the CSF.

Pia Mater

The inner layer of the meninges that nourishes the CSF and clings to the central nervous system.

Meningitis

An inflammation of the meningeal layer of the brain.

Cerebrospinal Fluid

A protective layer of the CNS, in the form of a liquid that is similar to blood plasma composition.

• Lateral Ventricles

• Third Ventricles

• Cerebral Aqueduct

• Fourth Ventricle

(4) Ventricles of the Brain

Blood-brain Barrier

A protective layer of the CNS that are made of semi-permeable capillaries.

Fat embolism

A condition where particles of fat enter you blood stream and block blood flow.

Spinal Cord

A continuation of the brain stem that conveys sensory impulses from the PNS to the CNS and conduct motor impulses to the periphery.

Horns

Areas of gray matter in the spinal cord.

Tract

Bundle of fibers inside the central nervous system.

Nucleus

A mass of nerve cell bodies and dendrites inside the central nervous system.

16 to 18 inches

The approximate length of the spinal cord.

Cranial Nerves

Twelve pairs of nerves that mostly serve the neck.

Olfactory Nerve

Optic Nerve

Oculomotor Nerve

Trochlear

Trigeminal Nerve

Abducens Nerve

Facial Nerve

Vestibulocochlear Nerve

Glossopharyngeal Nerve

Vagus Nerves

Accessory Nerve

Hypoglossal Nerve

(12) Cranial Nerves

Olfactory Nerve

The first cranial nerve responsible for the sensory of smell.

Optic Nerve

The second cranial nerve responsible for the sensory of vision.

Oculomotor Nerve

The third cranial nerve responsible for most eye movements.

Trochlear

The fourth cranial nerve that only moves the eye downward; via superior oblique.

Trigeminal Nerve

The fifth cranial nerve that is responsible for the sensory of the face and movement for chewing.

Abducens Nerve

The sixth cranial nerve that only moves the eye laterally.

Facial Nerve

The seventh cranial nerve that is responsible for the sensory of taste and movement to the face.

Vestibulocochlear Nerve

The eighth cranial nerve that is responsible for the sensory of balance and hearing.

Glossopharyngeal Nerve

The ninth cranial nerve that is responsible for the sensory of taste and movement to the pharynx.