Chapter 10 Nervous system

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97 terms · Nervous tissue and Brain

Action Potential

Sequence of changes in the membrane potential that occurs wehn a cell is stimulated to threshold. It includes Depolarization an repolarization; also called the nerve impulse anth cardiac impulse.

Brain stem

lower part of the brain that connects the brain with the spinal cord; consits of the midbrain, pons and medulla oblongata

Cerebellum

Part of the brain located under the cerebrum; it coordinates skeletal muscle activity.

Cerebrospinal Fluid (CF)

Cushioning fluid that circulates within the subarachnoid space around the brain and spinal cord.

Cerebrum

larges and uppermost part of the brain divided intow cerebral hemispheres. Ther are four lobes- frontal, parietal, temporal and occipital

Depolarize

Change in the membrane potential across the cell membrane with the inside of the cell becoming less negative or less polarized

Frontal lobe

Anterior portion of the cerebrum that controls voluntary skeletal activity and plays and importatn role in emotions critical thinking and ethical decision making.

limbic system

the emotional pain

Medulla oblongata

Part of the brain stem that controls vital functions such as respiratory and cardiovascularfunction

meninges

membranes that cover the brain and spinal cord; include the dura mater, arachnoid mater, and pia mater

myelin

White fatty material that covers some nerve fibers

neuron

Nerve cell that conduct the action potential (nerve impulse)

neurotransmitters

Chemical made within the axon terminal responsible for transmission of the signal across the synapse or junction.

occipital lobe

Cerebral lobe located in the back of the head; concerned primarily with vision.

parietal lobe

Lobe of the cerebrum concerned primarily with somatosensory function

repolarization

return of the membrane potential to its restin state after the nerve impulse

reticular formation

Complex network of nerve fibers that arises within the brain stem and projects into the lower cerebrum; causes arousal of the cerebrum so that the person does not slip into a coma.

synapse

Interaction between tow nerves where cemical transmission of the electrical signal occurs

Temporal lobe

Lobe of the cerebrum responsible for hearing smelling speech and memory

Central Nervous systme (CNS)

includes the brain and the spinal cord . located in the dorsal cavity spinal cord is enclosed in the spinal cavity

Peripheral nervous system (PNS)

located outside the CNS and consists of the nerves that connect the CNS with rest of the body

Neuroglia or glial cells

are the most abundant of the Nerve cells; most are located in the CNS; they support protect insulate nourish and care for the neurons.some participate in phaygocytosis; assist in the secretion of CFS; DO NOT conduct nerve impulses

astrocytes

Type of Glial cell; star shaped; most abundat of the glial cells; most diverse function; support the neurons structurally cover the entire surface of the brain and help form a protective barrier, called blood-barrier around the nurons of the CNS. barrier helps prevent toxic substance in the blood from entering the nervous tissue of the brain and spinal cord; secrete nerve growth factor that promot neuron growth and enhance synaptic development

ependymal cells

GLIAL CELL; lines the inside cavity of the brain and assit in the formation fo CFS

neuron

most important in the transmission of the electrical signals ;enables the nervous system to act as a vast sommunication network. Have many shapes and sizes some are short or extremely long up to 4 ft; NONmitotic do not give rise to primary malignant tumors

Dendrites

treelike structure that receive signals from other neurons and the transmit the signal toward the cell body

cell body

contains the nucleus and is essential for the lif of the cell

axon

is th long etension that transmists signals away from the cell body

axon terminals

End of the AXON extenstive to form many ; within these chemical neurostransmitters are stored.

Myelin

protects and insulates the axon.

Microglia

Glial cell; protective role; phagocytosis of pathogens and damaged tissue

schwann cells

glial cell; produc mylein sheath for neurons in the PNS assist in regeneration of damage fibers;lie outsdie the myelin sheath and are called the neurilemma. which are important in the regeneration fo a severed nerve

oligodendrocytes

GLIAL cell; produce mylein sheath of neurons in the CNS no neurilemma no schwann cells

Nodes of Ranvier

axonal areas not covered by myelin appear at regualr intervals along the myelinated axon.

Sensory neuron/ affeerent neurons

carries information from the periphery towards the CNS
found in both the CNS and PNS

motor neuron/ efferent neurons

carries information from the CNS towards the periphery
found in both the CNS and PNS

interneuron

type of neuron; only found in the CNS; form connections between sensory and motor neurons. plays a role in thinking learning and memory

nuclei

clusters of cell bodies located in the CNS

ganglia (singular: ganglion)

small clusters of cell bodies in the PNS

basal nuclei

patches of gray located in the brain but located in the CNS; help regulate body movement and facial expression. neurotransmitter dopamine is largely responsible for the activity.

Nerve impulse

is an electrical signal that conveys information along a neuron.

Resting membrane potential

refers to the electrical charge difference across the memnbrane of the resting neuron. inside the resting neuron is more negative than the outside (+) . cell is quiet. no impulse being transmitted

ALL-OR NOTHING

means that the height of each nerve impulse is the same. important because it ensures that the nerve impulse does not weaken as it travels the length of the long axon.

myelination

fast conduction nerve fibers; axons of moste nerves fibers are wrapped in myelin a fatty material. the nodes of Ranvier the axonal membrane is bare or unmyelinated . the nerve impulse arrives at the axon but cannot develp on any part of the membran covered with myelin. the nerve impulse can delvelp at teh nodes of Ranvier the bare axonal membran. the myelinated fiber the nerve impulse jumps from node to node.

Saltatory conduction

The nerve impulse jumping from node to node ; this increases the speed with wich the nerve impulse travels along the nerve fiber.

synaptic cleft

is a space . the space exists because the axon terminal of neuron A )presynaptic neuron) does not phyicall touch the dendrite of the neuron B (postsynaptic neroun)

receptor sites

Dendrites of nuron B cotnains these; places on the membran to which the neurotransmitters bind (acetylcholine binds to the receptor on dendrite B. each one has specific shape and accepts only those neurotransmitters that "fit" its shape

Right and Left cerebral hemispheres

the divsions of the cerebrum.

corpus callosum

where the cerebral hemisphers are joined together by bands of white matter that form a large fiber tract.

cerebral cortex

a thin layer of gray matter forms teh outer most portion fo the cerebrum

convolutions or gyri (singular; gyrus)

the surface of the cerebrum is folded into elevations that resemble speed bumps on a road.

sulci (singular sulcus)

grooves that separate Gyri ; deep one is called a FISSURE

Central sulcus

seperates the frontal lobe from the partial lobe. important landmark speparting the precentral and postcentral gyri.

Precentral gyrus

locate in the frontal lobe directly infront of the central sulcus.

postcentral gyrus

located in the parietal lobe directly behind the central sulcus.

lateral fissure

separates teh temporal lobe from the frontal and the parietal lobes

longitudinal fissure

seprates teh left and right cerbral hemispheres

primary motor area cortex

frontal lobe contains this; nerve impulses that orginate in teh motor area control the vuntary muscle movement.

homunculus

function of the precentral gyrus of the frontal lobe (means little man ) represents the amount of brain tissue that corresponds to a function of a particualr body part. two important points; each part of the body is controlled by specific area of the cerbral cortex of the precentral gyrus and the complicate nature of certain movemnts requrires large amounts of brain tissue.

broca's area

the part of the frontal lobe concerned with motor speech. in the left hemisphere

frontal eye field

area above broca's area; it controls voluntary movemnts of the eyes and eye lids

Primary somatosensory area (cortex)

it recevies senstaions from teh body also called the parietal lobe. primarly receives info from teh skin and muscles and allows you to experience th sensation of temperature pain light touch and proprioception. also concerned with reading speech and taste.

primary auditory cortex

contained in the temporal lobe; area that allows you to hear.

olfactory area

located in the temporal lobe controls smell

taste buds

sensory information in the tounge is interpreted in both the temporal and parietal lobes

Wenicke's area

broad region that is locate in the parietal and temporal lobes;concerned with the translation of thought into words.

visual cortex

located in the occipital lobe; sensory fibers from the eye send infromation to this where it is interpreted as sight.

speech area

located in an area that includes the temporal parietal and occipital lobes. most people it is located in the left hemisphere.

association areas

large areas of the cerebral cortes; concerened primarily with analyzing interpreting and intergrating information.

dyskinesia

a deficiency of doampine withing hte basal nuclei is called Parkinsons'. it is a movement disorder. characterized by teh follwoing ;a shuffling gait and uncoordinate gait rigity slowness of speech drooling and masklike facial espressions

shaking plasy

Parkinson's is sometimes called this due to the shaking (tremors)

diencephalon

second main area of the brain. located beneath the cerebrum and avoe the brain stem. includes th thalamus and hypothalamus

thalamus

located in the diencephalon serves as a relay station for most of the sensory fibers traveling from the lower brain and spinal cord region to the sensory areas of the cerebrum. sorts out the sensory infomration gives us a hint of the snsation we are to experience and directs the information to the specific cerebral areas for a more precise interpretation.

hypothalamus

is the second structure in the diencephalon; it is situated directly below the thalamus and helps regulate many body process including body temprature (thermostat) water balance and metabolism. since it helps regulate the function of the autonomic nerves it exterts an effect on the heart rate blood pressure and respiration; (Part of the diencephalon that regulates the pituitary gland, autonomic nervous system water balance appetite, temperature and emotions

Midbrain

extends from the lower diencephalon to the pons ;relays sensory and motor information ; contains nuclei that function as reflex centers for vison and hearing

Pons

bridge extends from the midbrain to the medulla oblongata ; composed primarily of tracts that act as a bridge from information traveling to and from several brain structures; important role in the regulation of breathing rate and rhythm.

vital center

also call medulla oblongata because its importance with regard to vital functions.

emetic center

located in the medulla oblongata vomiting center; can be activated directly or indirectly. Direct activation includes stimuli from the cerebral cortex stimuli from sensory organs and signals from the equilibrium apparatus of th inner ear.

chemoreceptor trigger zone CTZ

Indirect stimulation of the vomiting center comes from here; located in the floor of the fourth ventricle can be stimulated by emetogenic compounds such as anticancer drugs and opioids. signals from the digestive tract especially the stomach trave via the vagus nerve to here. this inturn activates the vomiting center.

cerebella peduncles

the cerebellum is connected to brain stem by three pairs. these stalks or connection allow the cerebellum to receive intergrate and deliver infromation to many parts of the brain and spinal cord.

reticular formation

extending through the entire brain stem with numerous connections to the cerebral cortex is a special mass of gray matter called ----; it is concerned with the sleep wake cycle and consciousness. signal passing up to the cerebral cortex from 'HERE" stimulate us keeping us awake and tuned in.

gaze center

other nuclei witing the reticualr formation include the (allows the eyes to track and object) and special group of cells that rhythmicall send signals to the muscles that control breathing and swallowing.

habituation

Reticualr formation is also concerend with this ; the process whereby the brain learns to ignore repetitive background information.

consciousness

state of wakefulness. depends on the reticular activation system (RAS) continously samples sensory information from all over the body and then slects and presents essential unusual and threatenting infomraiton to the higher structures in the cerebral cortex. different levels ; attentivenss alertness, relaxation and inattentiveness. Sleep occurs whenthe RAS is inhibited or slowed.

coma

is a hyporesponsive state with several stages from ranging from light to deep. lightest stages some reflexes are intact may respond to light sound touch and painful stimuli. deepening the reflexes are gradually lost and become unresponisve to all stimuli.

non rapid eymovement (NREM)

type of sleep cylce; four stages from light to deep in typical 8 hour sleep period a person regularly cycles through the various stage sof sleep decednig from light to deep and the ascending from deeper to lighter. then to stage to to REM sleep.

rapid eye movement (REM)

stage after NREM totals 90 to 120 mins per night. characterized by fluctuation blood pressure respiratory rate and rhythm and pulse rate. most common is the rapid eye movments. most dreams occur during this stage.

Memory

is the ability to recall thoughts and images. three catagories; immediate -last for a few seconds; short term last for short period of time seconds to a few hours.; and long term.-years decades or lifetime.

Dura mater

outermost layer of connective tissue (meninges) dural membranes split inside the skull to form the dural sinuses they are filled with blood. beneath this small space called the subdural space.

arachnoid mater

spider like- middle layer of the meninges .connective tissue

pia mater

innermost layer and literally means soft or gentle mother. ver thin membrane contains many blood vessels and lies delicatly ove the brain and spinal cord. supplies the brain with much of its blood.

subarachnoid space

lies between the arachnoid layer and pia mater . CSF circulates within thsi space and forms a cushion around the brain and spinal cord.

arachnoid villi

specialized projections of the arachnoid membrane ; protrude up into the blood filled dural sinues and are involved in the drainage of CSF.

choroid plexus

where CSF is formed within the ventricles of the brain . Four ventricles are to lateral and a third an foruth ventricle. this is like a grapelike collection of blood vessels and ependymal cells suspended from the roof of each ventricle. water and dissolved substance are trasnported from thh blood across the walls of the """ into the ventricles.

central canal

SOme of the CSF flows through a hole in the center of the spinal cord.. this eventually drains inot he subarachnoid space at the base of the spinal cord. the rest of the CSF flow from the fourth ventricle laterally through tiny holes or foramina into the subarachnoid space that encircles the brain

blood brain barrier

arrangement of cells particualry the glia astrocytes and the selectively permeable capillary cells that act as a barrie to movemnt of potentially harmful chemical into the CNS. the astroocytes and the capillary cells select the substance allowd to enter the CNS from the blood.

pituitary gland

directly or indrirectly affects almost every hormone in the body. the hypothalamus controls the function wides srpead effects are obovious.

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