Nervous System Anatomy and Physiology

Ch. 9 Intro. to Medical Terminology

sensory input

any electrical impulse sent from the sensory organs (the eyes, ears, nose, tongue, and skin) to the central nervous system (CNS)

integration

the CNS subconsciously processes and interprets the information received through the sensory organs

motor output

the CNS transmits messages to effectors, which are muscles or glands in the body that generate a response that occurs through the voluntary movement produced by skeletal muscle, or through the involuntary movement of muscles and glands

neurons (nerve cells)

fundamental cells of the nervous system, are found in the brain, spinal cord, and peripheral nerves, and are responsible for conducting electrical impulses throughout the body in response to an external or internal stimulus

sensory neurons

conduct electrical signals (impulses) from various parts of the body to the brain and the spinal cord

motor neurons

receive electrical impulses from the brain and spinal cord and communicate these impulses to other parts of the body

astrocyte

a large, star-shaped cell that holds nerve cells in place and helps them develop and work the way they should

electrochemical signaling

process of impulse transmission via the neurons

nerves

when many neurons form a bundle of fibers, the fibers are called ____

cell body

contains nucleus, cytoplasm, mitochondria, and organelles of nerve cells

dendrites

extend from the neuron cell body and receive the electrical impulses, or messages, from other neurons

axon

more commonly known as “nerve fibers,” they are long, thin nerve processes (projections) that transmit electrical impulses from the cell body of the neuron out toward the ____ terminals

myelin sheath

made up of fats and proteins; provides electrical insulation for the axons as they conduct neural (nerve) impulses

axon terminals

axons branch out from the cell body, ending in ____

synapse

contact point at which one neuron communicates with another

synaptic cleft

a microscopic gap between two neurons

neurotransmitters

chemical messengers that pass neural impulses across a synaptic cleft from one neuron to another

neuroglial (glial) cells

specialized cells that support the vital functions of the nervous system; provide protective insulation for the neurons and are the “glue” that hold the nerves together, but they do not conduct neural impulses; PNS and CNS

microglial cells

found in the CNS; remove damaged neurons and infections and are important for maintaining the health of the CNS

Schwann cell

myelinates the peripheral nervous system (PNS)

oligodendrocyte

myelinates the central nervous system (CNS)

central nervous system (CNS)

comprises the brain and the spinal cord; receives, processes, and responds to impulses from all over the body; command center of the body; constantly monitors internal and external environmental stimuli and regulates cognitive and motor responses to help the body maintain homeostasis

peripheral nervous system (PNS)

made up of nerves that reach into and extend from the brain and the spinal cord; functions as the liaison between the central nervous system and the rest of the body; includes cranial and spinal nerves that conduct impulses from sensory receptors to the CNS and from the CNS to muscles, organs, glands, and skin

cranial nerves

conduct neural impulses to and from the brain

spinal nerves

transmit neural impulses to and from the spinal cord

nodes of Ranvier

gaps between myelin sheaths in glial cells of the PNS

gray matter

unmyelinated nerve tissue that is composed mostly of nerve cell bodies and dendrites; found in outer cerebral cortex and inner spinal cord

white matter

contains myelin sheaths, which shroud axons, and are made by neuroglial cells; outer cortex, exterior spinal cord; contains microglial cells

nerve tract

bundles of nerve fibers

cerebrum

located in the superior and anterior parts of the brain, is the largest brain region; seat of high-level cognitive functions such as language, reasoning, planning, memory, and sensory integration

cerebral cortex

layer of gray matter contains many folds of convoluted (curved) and fissured (depressed) areas that increase the brain’s surface area, enabling the brain to process the information that is constantly being received by the sensory organs

gyri

convolutions in the cerebral cortex

sulci

depressions in the cerebral cortex

left brain

right side of body control, number skills, math/scientific skills, written language, spoken language, objectivity, analytical, logic, reasoning

right brain

left side of body control, 3-D shapes, music/art awareness, intuition, creativity, imagination, subjectivity, synthesizing, emotion, face recognition

corpus callosum

connects right and left brain hemispheres; 200-300 million neurons thick

frontal lobes

control movement, reasoning, planning, problem solving, speech, emotions, and are your personality

Brocca’s area

where 97% of all expressive language comes from

pre-frontal cortex

emotions attached to music; gatekeeper of inhibitions

motor strip

moving body parts

parietal lobes

situated in the superior part of the cerebrum; largely responsible for processing sensory stimuli related to touch, pressure, temperature, and pain; mid-term memory

sensory strip

processes sensory stimuli and sensory input to motor output

parietal proper

goal-directed movement, binary math, sensory analysis, analogies, comparisons, attention span, cause/effect

occipital lobes

vision or visual fields, reading, sight words, main memorization, visual memories, spatial relation, drawing, color, night vision, peripheral vision

temporal lobes

hearing, sense of smell, factual and visual memory, language processing → Wernicke

cerebellum

second largest region of the brain; located posterior to the cerebrum, behind the brain stem; controls your body’s sense of balance and equilibrium, and it coordinates movement of voluntary muscles

diencephalon

site of three key endocrine glands: thalamus, hypothalamus, pineal gland

thalamus

touch, processing, memory, memory function as a part of learning

hypothalamus

control center for ANS functions such as heart rate, blood pressure, body temperature, breathing, hormone production, hunger, thirst, and digestion, instincts, reflexes, thrill seeking, sexual desire, and orgasm

pineal gland

secretes melatonin, a hormone that helps regulate the body’s circadian rhythm

hippocampus

short term memory acquisition, orientation, sense of direction, memorization

amygdala

higher order emotions such as rage, jealousy, shame, PTSD, embarrassment, and response to rewards

pituitary gland

master gland, secretes many hormones; critical to respond appropriately to the environment; physical and sexual development (body can send signals with hormones)

pons

connects the cerebellum to the rest of the brain; coordination, equilibrium, balance; breathing rhythm

reticular activating system (RAS)

flight-or-flight response from sympathetic system, awareness or alertness, amount and flow of sensory input

medulla oblongata

(backup) connects the brain to the spinal cord via the pons; helps conduct neural impulses from the brain to the spinal cord and regulates vital autonomic functions such as breathing, heart rate, blood pressure, and body temperature

midbrain

serves as the passageway for electrical impulses as they travel between the brain and the spinal cord

medulla (brain stem)

connects the cerebrum with the spinal cord; helps regulate the central nervous system by serving as a conduit for sensory information carried between the cerebrum or the cerebellum and the rest of the body; governs vital functions such as respiratory rate, cardiac rhythm, body temperature, and sleep patterns

cerebrospinal fluid (CSF)

fills four cavities of the brain called ventricles; clear, watery fluid; envelops and protects the delicate brain and spinal cord tissues from injury

choroid plexus

manufactures cerebrospinal fluid in each ventricle of the brain

spinal cord

column of neural tissue that extends inferiorly from the medulla oblongata; divided into 31 segments that each contain a pair of spinal nerves and connect the CNS to the organs and tissues of the upper body and the limbs; provides support for the body and helps it to maintain equilibrium; protected by cerebrospinal fluid that flows through the central canal of the spine; exterior is white matter, interior is gray matter

ascending spinal tract

white matter is made up of the ____, which transmits sensory information from organs and glands to the brain

descending spinal tract

white matter is made up of the ____, which relays motor commands from the brain to one or more of the peripheral nerves

meninges

layers of connective tissue that protect the CNS

dura mater

Latin for “tough mother”; thick sac of dense collagen fibers and blood vessels that protects the CNS from injury; also contains cerebrospinal fluid, and it supplies blood to the nervous tissue of the CNS

pia mater

“soft mother”; a thin, delicate tissue membrane that lies directly on the brain and the spinal cord; contains a rich supply of blood vessels that nourish the CNS

arachnoid mater

means “spider-like mother” because this layer of the meninges contains many thin fibers that connect it to the pia mater below it; these fibers cross the sub-____ space between the ____ mater and the pia mater

sub-arachnoid space

filled with protective fluid

afferent nerves

nerves that conduct messages from sensory receptors to the CNS only

efferent nerves

conduct messages from the CNS to the muscles or glands of the body

autonomic nervous system (ANS)

controls the involuntary (unconscious) bodily functions

sympathetic nervous system

controls the body’s “fight-or-flight” response in times of crisis; gives a “rush” of adrenaline that equips your body to confront or flee from a threatening situation

parasympathetic nervous system

controls the “rest-and- digest” response that counteracts the adrenalized response generated by the sympathetic nervous system during a fight-or-flight experience; “calms” the body with signals that decrease heart rate and respirations and that resume digestion

somatic nervous system (SNS)

involves the skeletal muscles and the skin; controls the conscious, voluntary activities of the body; nerves send messages about pain, pressure, temperature, and touch to and from the brain and spinal cord