Chapter 12: Nervous System

dura mater

'tough mother'; is fibrous outermost meninges layer that forms a tough protective layer

meninges

3 connective tissue membrane layers that suround brain and spinal cord; 3 layers are dura mater, arachnoid layer and pia mater

vertebral canal

bony canal through vertebrae that contains spinal cord

parasympathetic branch

branch of autonomic nervous system; serves as counterbalance for sympathetic nerves; therefor it causes heart rate to slow down, lower bllood pressure, constrict eye pupils, and increase digestion

sympathetic branch

branch of autonomic nervous system; stimulates body in times of stress and crisis by increasing heart rate, dilating airways to allow for more oxygen, increasing blood pressure, inhibiting digestion, and stimulating production of adrenaline during crisis

dendrite

branched process off a neruon that receives impulses and carries them to cell body

tract

bundle of fibers located within central nervous system

muscles

bundles of parallel muscle tissue fibers; as fibers contract they pull whatever they are attached to closer together

central canal

canal that extends down length of spinal cord; contains cerebrospinal fluid

neuroglial cells

cells that perform support functions for neurons

neurotransmitter

chemical messenger that carries electrical impulse across gap between 2 neurons

occipital lobe

controls eyesight

temporal lobe

controls hearing and smell

frontal lobe

controls motor functions

gyri

convoluted, elevated portions of cerebral cortex, separated by sulci

arachnoid layer

delicate middle layer of meninges

cerebral hemisphere

division of cerebrum into right and left halves

spinal cavity

dorsal body cavity within spinal column that contains spinal cord

ventricles

fluid filled spaces within cerebrum; contain cerebrospinal fluid

synaptic cleft

gap between 2 neurons

ganglion

knotlike mass of nerve tissue located outside brain and spinal cord

brain

largest organ in body, controls body functions, four sections are cerebrum, cerebellum, diencephalon, and brain stem

cerebrum

largest section of brain; located in upper portain and is area that possesses thoughts, judgment, memory, association skills, and ability to discriminate between items; outer layer is cerebral cortex; elevated portions are called gyri; has 4 lobes: frontal, parietal, occipital and temporal

neuron

name for individual nerve cell; neruons group together to form nerves and other nervous tissue

myelinated

nerve fibers covered with layer of myelin

sensory receptors

nerve fibers located directly under skin surface; these receptors detect temperature, pain, touch and pressure; messages for these sensations are conveyed to brain and spinal cord from nerve endings in skin

afferent neurons

nerve that carries impules to brain and spinal cord from skin and sense organs; also called sensory neruons

descending tracts

nerve tracts carrying motor signals down spinal cord to muscles

ascending tracts

nerve tracts carrying sensory info up sinal cord to brain

cranial nerves

nerves that arise from brain

spinal nerves

nerves that arise from spinal cord

motor neurons

nerves that carry activity instruction from CNS to muscles or glands out in body; also called efferent neurons

efferent neurons

nerves that carry impules away from brain and spinal cord to musles and glands; also called motor neurons

sensory neurons

nerves that carry sensory info from sensory receptors to brian; also called afferent neurons

somatic nerves

nerves that serve skin and skeletal muscles and are mainly involved with onscious and voluntary activities of body

glands

organs of body that release secretions

cerebral cortex

outer layer of cerebrum; composed of folds of gray matter called gyro which are separated by sulci

vertebral column

part of axial skeleton; a column of 26 vertebrae that forms backbone and protects spinal cord; divided into 5 sections; cervical, thoracic, lumbar, sacrum, and coccyx

synapse

point at which axon of one neruon meets dendrite of next neuron

nerve root

point where spinal or cranial nerve is attached to CNS

midbrain

portion of brain stem

medulla oblongata

portion of brain stem that connects spinal cord with brain; contains respiratory, cardiac and blood pressure control centers

diencephalon

portion of brain that contains 2 of most critical areas of brain: thalamus and hypothalamus

hypothalamus

portion of diencephalon that lies just below thalamus; controls body temperature, appetite, sleep, sexual desire, and emotions; also regulates release of hormones from pituitary gland and regulates parasympathetic and sympathetic nervous systems

thalamus

portion of diencephalon; composed of gray matter and acts as center for relaying impulses from eyes, ears, and skin to cerebrum; pain perception is also controlled here

nerve cell body

portion of nerve cell that includes nucleus

central nervous system

portion of nervous system consisting of brain and spinal cord; receives impules from all over body, processes info, and responds with action; consists of gray and white matter

autonomic nervous system

portion of nervous system consisting of nerves to internal organs that function involuntarily; regulates functions of glands, adrenal medulla, heart, and smooth muscle tissue; system is divided into 2 parts: sympathetic and parasympathetic

peripheral nervous system

portion of nervous system that contains cranial nerves and spinal nerves; these nerves are mainly responsible for voluntary muscle movement, smell, taste, sight and hearing

spinal cord

provides pathway for impulses traveling to and from brain; column of nerve fibers that extends from medulla oblongata of brain down to level of second lumbar vertebra

parietal lobe

receives and interprets nerve impulses from sensory receptors

cerebellum

second largest portion of the brain, located beneath posterior portion of cerebrum; this part of brain aids in coordinating voluntary body movements and maintaining balance and equilibrium; is attached to brain stem by pons; refines muscular movement that is initiated in cerebrum

axon

single projection of a neuron that conducts impulse away from nerve cell body

subarachnoid space

space located between arachnoid layer and pia mater; contains cerebrospinal fluid

subdural space

space located between dura mater and arachnoid layer

nerves

structures in nervous system that conduct electrical impulses from brain and spinal cord to muscles and other organs

pia mater

term means soft mother; this thin innermost meninges layer is applied directly to surface of brain

brain stem

this area of brain has 3 components; medulla oblongata, pons and midbrain; it is the pathway for impulses to be conducted between brain and spinal cord; also contains centers that control respiration, heart rate, and blood pressure; 12 pairs of cranial nerves begin in the brain stem

pons

this portion of brain stem forms bridge between cerebellum and cerebrum; also where nerve fibers cross from one side of brain to control functions and movement on other side of brain

white matter

tissue in central nervous system; consists of myelinated nerve fibers

myelin

tissue that wraps around many nerve fibers; composed of fatty material and functions as insulator

gray matter

tissue within central nervous system; consists of unsheathed or uncovered nerve cell bodies and dendrites

cerebrospinal fluid

watery, clear fluid found in ventricles of brain; proveds protection from shock or sudden motion to brain