Anatomy

rapid activity (movement and thinking) vs. slow activity (growth)

a coordinating system of the body composed of a group of highly specialized cells for conducting nerve impulses to a center so responses can be made

the nervous system provides a control for the rapid activities of the body

• CNS - brain and spinal cord
• PNS

• 1) to receive stimuli from the environment (receptor)
• 2) to transform these stimuli into nerve impulses (receptor)
• 3) to transmit these impulses to the proper nerve center of the body (neuron)
• 4) to process the information and determine the appropriate response (brain, spinal cord)
• 5) this response is transmitted to the effector organ (neuron)
• 6) the effector organ carries out the response (effector)

neuron and neuroglia

functional unit of the NS

cytoplasmis extensions that receive information and transmit it toward the cell body

contains the nucleus and controls the metabolic activity of the neuron

connects the cell body to the axon

insulating substance which allows axons to conduct impulses faster

gaps between segments of myelin

swellings at the end of the axon, involved in neurotransmitter release

gap between the axon terminal of one neuron and the dendrite of another

supportive connective tissue that natures and protects the neurons

Schwann, Oligodendrocytes, Microglia, Astrocytes, Ependymal Cells, Satellite Cells

neurolemmocytes

form fatty myelin sheaths around the most axons in the PNS only; this insulatory material is not continuous along the axon but is interrupted at the nodes of Ranvier; the nerve impulses jump from node to node as they travel down the axon, a conduction called saltatory conduction

form similar myelin sheaths in the CNS only

phagocytic cells that migrate throughout the CNS removing debris; may migrate to areas where nervous tissue is injured

regulate the passage of molecules from blood to the brain; helps form the blood-brain barrier that regulates the passage of substances into the brain

line the brain chambers called ventricles and help form the choroid plexus; which produces cerebrospinal fluid

support neuron cell bodies in ganglis of the PNS

• astrocytes
• microglia
• oligodendrocytes
• ependymal cells

• schwann cells
• satellite cells

multipolar: 2 or more braches of the soma

bipolar: 2 branches of the soma

unipolar: 1 branch of the soma

SAME

sensory

transmit sensory nerve impulses from receptors to the brain and spinal cord

Motor

convey motor nerve impulses from the brain and spinal cord to effectors (muscles and glands)

Internuncial neurons

carry impulses from one neuron to another; makes up the majority of nerves in the body

travel the length of the axon and invade the nerve terminal, thereby causing the release of neurotransmitter into the synapse

hangs by a stalk from the hypothalamus of the brain

posterior and anterior

appears fibrous

neurons produce ADH, and antidiuretic hormone, and oxytocin

ADH is stored in, and released from, the post. pit. gland in response to neural stimulation from the hypothalamus via the hypothalamohypophyseal system

appears glandular

develps from epithelial tissue that pinches off from the roof of the embryo's mouth

produces the hormones it secretes: growth hormone, ACTH, thyroid-stimulating hormone, luteninizing hormone, follicle-stimulating hormone, prolactin, melanocyte-stimulating hormone

shaped like a bowtie or shield and lies just below the Adam's apple in the front of the neck

thryoxine helps set basal metabolic rate by stimulating the rate of cell respiration

in children, thyroid hormones also promote growth and stimulate maturation of the CNS

four small glands attached to the posterior surface of the thyroid gland

produces parathyroid hormone, which is involved in calcium homeostasis

located above each kidney

each gland is composed of an inner portion (medulla) and an outer layer (cortex)

hormones from adrenal cortex are collectively referred to as corticosteroids

secretes epinephrine and norepinephrine in response to the ANS

located adjacent to the stomach and is connected to the duodenum by the pancreatic duct

secretes insulin and a variety of digestive enxymes into small intestine

produce androgen

associated with secondary sexual characteristics

secretes melatonin

regulates biological clocks

any chemical that can bind to receptor proteins and mimic the effects of the hormone

frontal, parietal, occipital, temporal, and insula

insula lies within the depths of the lateral sulcus

largest part of the brain consisting of two hemispheres

gyri: convolutions of the cerebrum separated by sulci

contains various fissures and large sulci

separates the right and left hemispheres and is occupied by the falx cerebri

separates the cerebrum and cerebellum and is occupied by the tentorium cerebelli

separates the temporal lobe from the rest of the cerebrum

the precentral (motor) and postcentral (sensory) gyri

the primary motor cortex is precentral gyrus; it lies anterior to the central sulcus

the primary sensory cortex is the postcentral gyrus; it lies posterior to the central sulcus

constitutes the central gray matter of the cerebrum

• function in control of movement and posture
• - diesease involve disturbances in voluntar muscular control (Parkinson's, Huntington's)

most important sensory relay center of the brain

it sends incoming impulses from the receptors of the body to the cerebral cortex

• it lies between and is associated with the:
• 1) Optic Chiasma: where optic tracts (CNII) cross
• 2) Mammillary bodies: sensory synaptic station
• 3) Pituitary Gland: projects inferior from it and secretes many hormones

Functions in the regulation of visceral activity (body temperature, carb and lipid metabolism, sleep, sexual activity, and emotions)

part of the brain directly continuous with the spinal cord and will contain most of the ascending and descending tracts of the spinal cord

represents an area where pyramidal tract fibers lie, called the pyramids: contain several nuclei involved in the regulation of the vital body activities: respiratory, cardiac (HR), vasomotor (BP)

acts as a bridge connecting the right and left cerebellar hemispheres

relay impulses from the cerebral cortex to the cerebellum

little brain

connects with the midbrain, pons, and medulla oblongata; consists of two hemispheres separated by a median vermis; outer cortex contains folia separated by fissures, folia means leave; internally presents white matter branching in the form of a tree, called the arbor vitae; functions to coordinate muscular activity, regulate muscle tone, and maintain muscle equilibrium

• consists of 4 elevations
• - superior colliculi involved in the pathway of vision
• - inferior colliculi involved in the pathway of hearing

• midbrain
• pons
• medulla oblongata

area of cell bodies within the CNS

area of axons or fibers within the CNS

arises from the dorsal surface of the spinal cord; contains sensory neurons only

enlarged part of the dorsal root

area of cell bodies outside the CNS

contains cell bodies of sensory neurons

arises from the ventral surface of the spinal cord

contains motor neurons only

joins with the dorsal root to form the SPINAL NERVE

divides into a larger ventral ramus which supplies the entire anterior trunk as well as the appendages

smaller

supplies all the structure of the back

long cyndrical mass of nervous tissue that occuplies the upper 2/3 of the vertebral canal; connected to the brain superiorly where it is continuous with the medulla oblongata and extends to the level of LV2; presents enlargements in the cervial and lumbar regions where cell bodies of the neurons for the upper and lower limb are located; lower end of the cord is termed CONUS MEDULLARIS; below LV2 is the CAUDA EQUINA which consists of the very long roots of the lower spinal nerves which descend in a bundle from the conus medullaris

the brain and spinal cord are surrounded and protected by three layers of connective tissues, collectively termed meninges

from external to internal, dura mater, arachnoid mater, pia mater

outermost meninge composed of tough fibrous connective tissue; dura of the spinal cord extends from the foramen magnum where it is continuous with the dura mater that surrounds the brain and then courses inferiorly to the coccyx in the vertebral canal; this space external to the dura mater is the epidural space: contains adipose tissue in the form of globules of fat and veins and contains the vertebral venous plexus

intermediate meninge

delicate, loose, netlike membrane that extends from the foramen magnum where it is continuous with the cerebral arachnoid inferiorly through the vertebral column to coccyx; separated from the pia mater by the subarachnoid space which contains CSF

innermost meninge

very delicate connective tissue that adheres to the surface of the brain and spinal cord; extends from the foramen magnum to the coccyx

periphery means along the outside

extends beyond the CNS, thus includes all the nervous tissue structures except the brain and spinal cord

most not protected by bone

composed of 12 prs of cranial nerves and 31 prs of spinal nerves

• 8 prs of cervical
• 12 prs of thoracic
• 5 prs of lumbar
• 5 prs of sacral
• 1 pr of coccygeal

sensitive to chemical substances in the immediate area

stimulated by mechanical forces like pressure

sense the degree of muscle contraction, the movement of ligaments, and the stretch of tendons

stimulated by changes in temperature

nocioceptors

detect light

senses that are associated with the skin, muscles, and joints

proprioception is a sense of knowing the position of the limbs

sense organs for taste, smell, vision, equilibrium, and hearing

contains receptors for touch, pressure, pain, and temperature

adaptation occurs when a receptor becomes accustomed to stimulation and stops generating impulses, even though the stimulus is still present

taste buds are groupings of cells found in the tongue epithelium and open at a taste pore; recent functional and molecular data have found that there is no tongue "map": where certain areas are responsive to the 5 basic modalities- bitter, sour, sweet, salty, and umami - all modalities are present in all areas of the tongue

our sense of smell is dependent on olfactory cells found in the roof of the nasal cavity

• eyeball is an elongated sphere about 2.5cm in diameter and has 3 layers:
• -sclera: outer layed, white and fibrous except for the transparent cornea known as the window of the eye
• - choroid: middle, dark, think brown layer; toward the front it thickens and forms the ringshaped ciliary body which contains ciliary muscle which controls the shape of the lens for near and far vision; it becomes thin, circular, muscular, pigmented diaphragm called the IRIS which regulates the size of the pupil
• - retina: inner layer containing rods and cones, there are no cones or rods where the optic nerves passes through which is called the blind spot; vision is most acute in the fovea centralis

in diabetic retinopathy, capillaries to the retina burst and blood spills into the viteour humor, this blinds people between 20 and 74 yrs old

galucoma occures when the eye drainage system fails so that fluid builds up, destroys nerve fibers that are responsible for peripheral vision

most common cause is careless use of contacts, increases cataracts in heavy smokers, wear sunglasses that absorb UV light, glasses with large lenses offer better protection than smaller

hearing and equilibrium (balance)

pinna (external flap made of cartilage and skin) and the auditory canal

begins at the tympanic membrane (eardrum) and ends at a wall containing the oval window (the round window is near this area and allows fluid in the cochlea to move)

• 3 bones are between the eardrum and oval window:
• - malleus (or hammer): attaches to the tympanic membrane
• - incus or anvil
• - stapes or stirrup: contacts the oval window

semicircular canals and the vestibule are involved with equilibrium; cochlea is involved with hearing; cochlea appears snail-shaped and is lined with small hairs called stereocillia; the movement of these hairs transmits sensation to our brain to interpret sound; eustachian tube (auditory tube) extends from the middle ear to the nasopharynx - this permits equalization of air pressure when we swallow or yawn

limiting exposure to loud noises; any noise over 80 decibels may damage hair cells of the organ of corti and cause them to disappear completely; tinnitus (ringing in ears); anticancer drugs or certain anitbiotics may increase sensitivity to loud noises

muscles: smooth, cardiac, skeletal

glands: endocrine, exocrine

responsible for the control of smooth muscle, cardiac muscle, endocrine glands, and exocrine glands

autonomy means self-government