Integration: Processing and interpretation of sensory input

Motor Input: Activation of effector organs (muscles and glands) produces a response

Sensory Input: Information gathered by sensory receptors about internal and external changes

CNS: The Central Nervous System consists of the brain and spinal cord of the dorsal cavity. The CNS is the integration and control center and it interprets the sensory input and dictates motor output.

Neuroglia of PNS: Consists of Satellite and Schwann Cells. The Satellite Cells surround neuron cell bodies in the PNS and function similarly to astrocytes of the CNS. The Schwann Cells surround all peripheral nerve fibers and form myelin sheaths in thicker nerve fibers which is a similar function as oligodendrocytes. The Schwann Cells are vital to the regeneration of damaged peripheral nerves.

Bipolar: Two processes (one axon, 1 ore dendritic). This type is rare and is found in retina and olfactory mucosa.

Unipolar: One T-like process (two axons). Also referred to as pseudounipolar

Multipolar: Three or more processes (1 axon, other dendrites). Most common and major neuron type in CNS.

Sensory: Transmits impulses from sensory receptors towards CNS and almost all are Unipolar. The cell bodies are located in the ganglia in the PNS.

Motor: Carries impulses from CNS to effectors. These neurons are multipolar and most cell bodies are located in CNS (except some autonomic neurons)

Interneurons: Also referred to as "association neurons" these cells lie between motor and sensory neurons. These neurons shuttle signals through the CNS pathways and most are entirely within the CNS. 99% of the body's neurons are interneurons.

Dura Mater: Most external and strongest layer of the meninges

Arachnoid Mater: The middle layer of the meninges with spiderweb-like extensions separated from the dura mater by subdural space. The subarachnoid space contains CSF and largest blood vessels of brain.

Pia Mater: Delicate connective tissue that clings tightly to brain, following every convolution. It also contains tiny blood vessels that feed brain.

Thalamus: Acts as a relay station for information coming into cortex. It sorts and edits, and relays ascending information. Some examples of this are impulses from the hypothalamus for regulating emotion and visceral functions.

Hypothalamus: Located below the thalamus, the hypothalamus forms a cap over the brain stem and forms inferolateral walls of the third ventricle. It contains various important nuclei such as the mammillary body and it also contains the infundibulum. The thalamus controls the ANS and initiates physical responses to emotion.

Epithalamus: The most dorsal portion of the diencephalon, this forms the roof of the third ventricle and contains the pineal gland (body). It extends from the posterior border and secretes melatonin that helps regulate sleep-wake cycle.

Medulla Oblongata: Often referred to as the "medulla", this part blends into the spinal cord at the foramen magnum and contains the fourth ventricle. Its functions include being the cardiovascular center and the respiratory center.

Pons: Located between the midbrain and the medulla oblongata the pons is separated from the cerebellum by the fourth ventricle. Some nuclei play a role in the reticular formation and some help maintain normal rhythm of breathing.

Midbrain: Located between the diencephalon and pons the midbrain consist of the cerebral peduncles, the cerebral aqueduct, and the corpora quadrigemina.

Denticulate Ligaments: These ligaments are extensions of the pia mater that secure the cord to the dura matter. The cervical and lumbar enlargements are areas where nerves servicing upper cord lower limbs arise from the spinal cord.

Spinal Nerves: Parts of PNS attach to spinal cord by 31 paired roots and each spinal cord segment is designated by 31 paired roots. The spinal cord segments are designated by paired spinal nerves that arise from it.

Filum Terminate: Extending to the coccyx this fibrous extension of conus covered with pia mater anchors the spinal cord.

Cauda Equina: These collection of nerve roots are located at the inferior of the vertebral canal.

Function: The Spinal cord provides two-way communication to and from the brain and body and it acts as a major reflex center since reflexes are initiated and completed at the spinal cord.

Epidural Space: The epidural space is a cushion of fat and network of veins in the space between between vertebrae and the spinal dura matter.

Action Potentials: Principal way neurons send signals which means they are the long-distance neural communicators. AP only occurs in muscle cells and axon neurons. AP's do not decay over distance as graded potentials do and in neurons they are the nerve impulse. The AP involves the opening of specific voltage-gated channels.

1. Resting State: Resting state is when all gated Na+ and K+ channels are closed

2. Depolarization: The Na+ channels open. Depolarizing local currents open the Na+ channels and the Na+ rushes into the cell. The influx of Na+ causes depolarization.

3. Repolarization:. Na+ channels are inactiating and K+ channels give. The Na+ channels inactivation causes the gates to close and the AP spike stops rising. The voltage gated K+ channels open allowing it to exit the cell down the electrochemical gradient.

4. Hyperpolarization: Some K+ channels remain open, and Na+ channels reset. Some of the K+ channels remain open allowing excessive K+ efflux. This causes hyperpolarization of the membrane which allows the channels to reset.

III. Oculomotor Nerves: The fibers of this nerve extend from the ventral midbrain through the superior orbital fissures to four of six extrinsic eye muscles. These nerves allow us to raise our eyelids, direct our eyeballs, constricting of the iris, and controlling lens shape.

IV. Trochlear Nerves: These nerves direct the eyeball. Its fibers come from the dorsal midbrain and enter the orbis via the superior orbital fissures.

II. Optic Nerves: Providing us with our sense of vision, this nerve arises from the retinas. It passes through the optic canals, converges, and partially crosses over at the optic chiasma.

VI. Abducens Nerves: Primarily a motor, innervating lateral rectors muscle, the fibers from nerves enter orbits via the superior orbital fissures.

I. Olfactory Nerves : These nerves give us our sense of smell. It's functions are purely sensory and carry afferent impulses for the sense of smell.

V. Trigeminal Nerves: The largest of the cranial nerves, its fibers extend from the pons to the face. These nerves have three divisions: Ophthalmic, which passes through the superior or orbital fissure, the Maxillary which passes through the foramen rotundum, and the mandibular which passes through the foramen ovale. These nerves convey sensory impulses for, various areas of the face.

XII. Hypoglossal Nerves: These nerves innervate extrinsic and intrinsic muscles of the tongue that contribute to swallowing and speech. The fibers run from the medulla and exit the skull via the hypoglossal canal.

VIII. Vestibulocochlear Nerves: Formerly known as the auditory nerve, this nerve serves the function of giving us our sense of hearing. It consists of afferent fibers from hearing receptors and equilibrium receptors.

IX. Glossopharyngeal Nerves: The primary function of these nerves is too innervate part of the tongue and pharynx for swallowing. The sensory functions are to conduct taste and general sensory impulses from the pharynx and posterior tongue.

X. Vagus Nerve: Helping to regulate activities of heart, lungs, and abdominal viscera as well as carry impulses from thoracic and abdominal viscera baroreceptors, chemoreceptors, and taste buds of the posterior tongue and pharynx. These are the only cranial nerves that extend beyond the head and neck region.

VII. Facial Nerves: With the functions including facial expressions, parasympathetic impulses to lacrimal, salivary glands, and two-thirds of the tongue, the fibers from this nerve travel through the internal acoustic meatus, and emerge through the stylomastoid foramen to lateral aspect of the face.

XI. Accessory Nerves: These nerves exit the skull via the jugular foramina to innervate trapezius and sternocleidomastoid muscle. These rootlets pass into the cranium via each foramen magnum.

There are 8 pairs of cervical nerves (C1-C8). 12 pairs of thoracic nerves (T1-T12). 5 pairs of lumbar nerves (L1-L5). 5 pairs of sacral nerves (S1-S5). 1 pair of tiny coccygeal nerves (C0).

Dorsal Roots: Contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia that conduct impulses from peripheral receptors.

Ventral Roots: Contain motor (Efferent) fibers from ventral horn motor neurons that innervate skeletal muscles.

2) Sensory Neuron: Transmits afferent impulses to CNS

3) Integration Center either monosynaptic or polysynaptic region within CNS

4) Motor Neuron: Conducts efferent impulses from integration center to effector organs

5) Effector: Muscle fiber or gland cell that responds to efferent impulses by contracting or secreting

Reflexes are classified functionally as somatic reflexes (activates skeletal muscle) and Autonomic (visceral) reflexes (Activates visceral effectors)

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