Nervous Systerm

Description:	BYU PdBio 305 Rhees Nervous System
Category:	Physiology
Created by:	droid on 2008-02-04

Question	Answer
Two divisions of nervous system	central nervous systerm, peripheral nervous systerm
Central nervous system	brain and spinal cord
Peripheral nervous systerm	nervous outside the brain and spinal cord
CNS composed of…	white matter and gray matter
Gray matter	nerve cell bodies
White matter	myelinated axons
Nerve tract	group of nerve fibers within the cns with a common origin and a common destination (ascending and descending)
Nucleus	cluster of nerve cell bodies within the CNS
Nerve	group of nerve fibers in the PNS with a common origin and common destination- afferent (sensory) and efferent (motor)
Ganglion	cluster of nerve cell bodies in the PNS
Structural components of nervous system	CNS and PNS
Fxnl components of nervous systerm	Autonomic Nervous systerm (ANS), Somatic nervous system
4 principal fxns of the nervous system	1. Orientation of body to internal and external environments. 2. Coordination and control of body activities. 3. Assimilation of experiences requisite to memory. 4. Programming of instinctual behavior (more important in vertebrates other than humans).
Cerebral palsy	pathology of the brain causing paralysis, lack of coordination, and other dysfunctions of motor and sensory mechanisms.
Coma	varying degrees of unconsciousness that may be the result of any one of a number of causes
Neurological examination	mental assessment following trauma to the CNS. 5 categories: 1. Mental status and speech 2. cranial nerves 3. motor system 4. sensory system 5. reflexes
Paraplegia	permanent paralysis of both legs due to injury or disease of the spinal cord.
Quadriplegia	permanent paralysis of arms and legs due to spinal cord injury or certain diseases.
Neuron	nerve cell; structural and functional unit of the nervous system
3 components of neuron	cell body, dendrites, axons
cell body	enlarged portion of the neuron containing the nucleus, Nissl bodies (layered rough ER), neurofibrils (strands of protein), and other organelles
dendrites	cytoplasmic extensions which receive stimuli and conduct impulses to the cell body
Axons	cylindrical processes that conduct impulses away from the cell body
Length of axons	few millimeters in the CNS to over a meter in the PNS
Schwann cells	long axons are generally myelinated with schwann cells in the pns
Oligodendrocytes	long axons are generally nyelinated with oligodendrocytes in the CNS
Nodes of Renvier	segments in the myelin sheath
Presynaptic terminals	where axon terminates
How are neurons classified?	direction of impulse conduction, the number of cytoplasmic processes, and the are of innervation
Impulse conduction direction neurons	afferent (sensory), efferent (motor), interneurons
Afferent	sensory neurons transmit nerve impulses to the CNS
Interneurons (internuncial or association neurons	conduct impulses between sensory and motor neurons
Efferent	motor neurons conduct impulses away from the CNS
Number of processes neurons	multipolar, bipolar, unipolar
Multipolar neurons	have one axon and two or more dendrites
Bipolar neurons	one axon and one dendrite
Unipolar neurons	have a single process, which branches into an axon and a dendrite
Area of enervation neurons	somatic afferent, somatic efferent, visceral afferent, visceral efferent
Somatic afferent neurons	within the skin, muscles, and joints receive stimuli and convey impulses to the CNS
Somatic efferent neurons	convery impulses from the CNS to skeletal muscles
Visceral afferent neurons	convey impulses to the CNS from the internal organs
Visceral efferent neurons	convey impulses from the CNS to internal organs (cardiac muscle, glands, and smooth muscle within visceral organs)
Resting membrane potential	when a neuron is not conducting an impulse (resting), there is a difference in electrical charge between the inside and the outside of the cell membrane
Resting membrane charge difference	more positive ions outside the membrane and more negative ions on the inside
3 mechanisms responsible for the imbalance in particles across the membrane	Na-K pump moves Na+ outside and K+ inside; cell membrane is more permeable to K+ than Na+ so K+ moves out faster than Na+ moves in; membrane doesn’t allow negative proteins through and therefore keep more anions inside than outside
3 action potential synonyms	spike, nerve impulse, discharge
Do action potentials diminish as they are conducted down an axon?	no
What constitutes the code as well as the destination of the impulse?	the frequency and pattern of the action potential
Are action potentials similar in all organisms?	yes
Membrane potential	present in all cells
Current in membrane potential	-60 to -80 mV (inside cells)
Action potential recorded by…	oscilloscope
Time for action potential to occur	2 msec (1000 per sec)
5 Characteristics of action potential	rising phase, overshoot, falling phase, undershoot or hyperpolarization, gradual restoration of the resting potential
Sequence of action potential (first 5 steps)	1.Adequate stimulation 2.open sodium channels 3. Sodium ions move inward 4. Threshold level (all or none) 5. Depolarization of membrane
Sequence of action potential (steps 6-10)	6. Reverse polarization 7. Acts as a stimulus 8. Decreased sodium permeability and increased potassium perm 9. K+ moves out (repolarization) 10.prep for next impulse
Action potential 1	adequate stimulation of membrane-physical, chemical, temperature-different neurons/different stimuli
Action potential 2	Increased membrane permeability to sodium at site of stimulation (open sodium channels)-permeability favors sodium over potassium
Action potential 3	sodium ions move inward- inside of the membrane becomes less negative
Action potential 4	there is a critical level- threshold level- generator potential (-55 mV) that must be crossed in order to trigger an action potential- “all or none” (voltage gated sodium channels open)
Action potential 5	if the action potential is triggered the transmembrane potential reaches zero (depolarization of membrane)
Action potential 6	sodium ions continue to move inward and the inside of the membrane becomes positive (reverse polarization) relative to the outside
Action potential 7	reverse polarization acts as a stimulus to the adjacent regions
Action potential 8	decreased permeability of sodium channels and increased (continued) permeability of potassium channels – voltage-gated potassium channels are opened
Action potential 9	potassium ions move out, making the outside positive (repolarization)
Action potential 10	to prepare for the next impulse, pumps transport sodium back out of the neuron, and potassium back into the neuron
All or none	nerve and muscle fibers obey the al or none law, meaning that a threshold stimulus evokes an action potential, and that a subthreshold stimulus evokes no response
Absolute refractory period	during the interval from the onset of an action potential until repolarization is about 1/3 completed, a second stimulus cannot elicit another response because the channels are already open
Relative refractory period	following the absolute refractory period is an interval during which the neuron will not respond to a normal threshold stimulus, but a very strong stimulus can depolarize the membrane and produce a second action potential
Sodium Channel structure is formed by what?	a single, long polypeptide
How many domains are on the sodium channel structure?	4 distinct domains
each sodium channel domain constists of what?	6 transmembrane alpha helices
Tetrodotoxin (TTX)	sodium channel toxin which binds to and physically blocks the Na+ pores
Saxitoxin	sodium channel toxin that blocks Na+ pores
Batrachotoxin	sodium channel toxin that cuases the Na+ channels to open and stay open much longer than normal, thus altering the action potentials
delayer rectifier	movement of K+ during repolarization occurs about the same time the Na+ channels close (one msec later)
orthodromic conduction	impulses moving in the normal direction (natural)
antidromic conduction	backward propagation (experimentally) of impulse
average impulse travel time	10m/sec (vary from .5m/sec to 100m/sec
Mylinated speed vs. unmylinated	mylinated is much faster
Nodes of ranvier	interruptions in the myelin sheath that make it myelinated
Salutatory conduction	the leaping of action potentials on mylenated neuron (increases speed and conserves energy
Schwann cells	form the myelin sheath in the pns
Oligodendroglia	form the myelin sheath in the cns
Multiple sclerosis (MS)	2nd most common cns disease next to epilepsy. Autoimmune disease in which the body’s natural defenses attack the myelin in the CNS. Myelin sheath becomes damaged and this interferes with nerve conduction. More common in cold areas
Symptoms of MS	disturbances in speech, disturbances in vision, numbness, fatigue, depression, loss of coordination, uncontrollable tremors, loss of bladder control, memory problems, paralysis
Treatment of MS	ACTH, exercise, physical therapy
Tay-Sachs disease	an inherited disease in which the myelin sheaths are destroyed by excessive accumulation of lipids within the membrane layers
Local anesthesia	drugs (cocaine and lidocaine) that block the initiation of action potentials in neurons. They are injected into the are of the body to be anesthesized.
Lidocaine binding site	S6 alpha helix of domain IV
Synapse	anatomical junction between two neurons where the electrical impulse in one neuron initiates a series of events influencing the excitability of the 2nd
Parts of a synapse	axon terminal, synaptic cleft, postsynaptic membrane
Axon terminals	small rounded or oval knobs which are referred to as synaptic knobs, boutons, and end feet, or presynaptic terminals. Present within axon terminals are synaptic vesicles containing a neurotransmitter: Ach, Norepi
Synaptic cleft	microscopic space between the 2 neurons
Postsynaptic membrane	cell membrane of the postsynaptic neuron which contains specific receptors for the neurotransmitter
Synapse sequence of events (first 3)	impulse reaches the axon terminal of the presynaptic neuron, Ca+ enters the presynaptic neuron cuasing release of neruotransmitter into synaptic cleft, neurotransmitter diffuses across synaptic cleft and is detected by receptors on the postsynaptic neuron
Synapse sequence of events (#4 and #5)	the postsynaptic membrane is either stimulated or inhibited depending upon the types of neurotransmitter involved, the neurotransmitter either diffuses out of the cleft or is metabolized
Characteristics of a synapse	1. Synaptic delay 2. Synaptic fatigue 3. One-way conduction
Drugs may influence synaptic transmission by altering any of the following steps	synthesis of the neurotransmitter, release of the neurotransmitter, binding of the neurotransmitter with the receptor, destruction of the neurotransmitter
Deseases which affect synaptic transmission	parkinson’s disease-lack of neurotransmitter (dopamine), Myasthenia Gravis-block neurotransmitter (Ach) receptors, Botulism- inhibition of Ach release, Nerve Gas- anti cholinesterase
Synaptic Integration	an single neuron can be, and often is, simultaneously stimulated by excitatory and inhibitory transmissions from different presynaptic neurons.
Excitatory/inhibitory neurotransmitters	neurotransmitters may be excitatory, causin the postsynaptic neuron to become active, or inhibitory, preventing the post synaptic neuron from becoming active
Synaptic excitation	excitatory neurotransmitters increase the postsynaptic membrane’s permeability to sodium ions.
EPSP	excitatory postsynaptic potential- altered membrane potential said to be hypopolarized-two ways in which EPSP’s may combine to reach threshold and initiate an action potential: spatial summation, temporal summation
spatial summation	several p presynaptic neurons simultaneously release neurotransmitters to a single postsynaptic neuron; these EPSP’s produced at different synapses may summate in the postsynaptic dendrites and cell body
Temporal summation	the EPSP’s may summate as the result of the rapid successive discharge of neurotransmitter from the same presynaptic terminal
Synaptic inhibition	inhibitory neurotransmitters increase the postsynaptic membran’s permeability to Cl- and K+, resulting in a hyperpolarized membrane that exhibits an inhibitory postsynaptic potential (IPSP)
Glycine	amino acid that is a neurotransmitter known to be involved in the production of IPSP’s. It’s action is messed up by strychnine and tetanus toxin which produce convulsions and muscular hyperactivity.
GPSP	Grand postsynaptic potential-composite potential on the postsynaptic membrane due to the sum of all EPSP’s and IPSP’s occurring at the same time
6 classes of neurotransmitters	1. Acetylcholine 2.amino acids 3.amines 4.polypeptides 5.purines 6.gases
Amino acid neurotransmitters	glutamate, GABA (gamma-aminobutyric acid)-inhibitory, Glycine-mainly inhibitory
Amine neurotransmitters	derived from a single amino acid- Norepinephrine (noradrenaline), Epinephrine (adrenaline), Dopamine-made from tyrosine, Serotonin (5-hydroxtryptamine) made from tryptophan, histamine-made from histadine
Polypeptide neurotransmitters	substance P, endorphins and enkephalins
Gas neurotransmitters	Nitric Oxide (NO)-made from oxygen and arginine, freely diffuses into cells and binds to proteins, has a half-life of 2-30 seconds and is difficult to study
Cerebrum	largest and most prominent part of the brain (80% of total brain mass)
Grooves or valleys, called fissures or sulci in brain	Longitudinal fissure, Central fissure, Lateral fissure
Gyri	convolutions or folds in brain
Corpus callosum	two cerebral hemispheres are connected to each other by a thick band called corpus callosum, which is made up of 300 million neural axons allowing the 2 sides to communicate and cooperate
Right hemisphere	creative and artistic perception
Left hemisphere	logic, analytical ability, language
Lobes of cerebrum	frontal, parietal, temporal, occipital
Frontal lobe	motor area, elaborate thought, speaking ability
Parietal lobe	sneosry area, somethetic (body feelings-touch, pressure, heat, cold, pain); proprioception (body positions)
Temporal lobe	hearing
Occipital lobe	visual input
Cerebral cortex	outer portion of cerebrum-3/16”-gray matter (six layers of neurons)
Functions of the cerebrum	all conscious fxns, interpretations of sensations, understanding of language, intelligence, memory, emotional feelings
Functions of the thalamus	recognition of crude sensations of pain, temp., touch; feelings of pleasantness and unpleasantness; production of complex reflex movements; relay center-receives all sensory input, except for smell, then relays it to the sensory cortex
Hypothalamus functions	controls the pituitary (hormones; thyroid, growth, reproduction, adrenal), water balance (ADH), appetite and food intake (glucostats-receptors for glucose), body temp., direct and indirect inputs to the autonomic nervous system
Hypothalamus blood brain barrier	not very well developed
Cerebellum functions	Control muscle action (planning and execution of voluntary movements), postural reflexes, equilibrium
Medulla Oblongata functions	controls heart rate, blood pressure, respiration, reflexes of vomiting, coughing, hiccupping
Pons function	center for the 5th, 6th, 7th, and 8th cranial nerves
Midbrain function	center for the 3rd and 4th cranial nerves
Brain stem consists of	medulla, pons, and midbrain
Reticular activating center	widespread network of interconnected neurons running throughout the entire brain stem and thalamus.
Function of reticular activating center	It controls the overall degree of alertness, wakefulness and sleep. General anesthetics suppress the neurons in this center and damage to these neurons may lead to a coma.
12 cranial nerves	1.Olfactory 2.Optic 3.Oculomotor 4.Trochlear 5.Trigeminal 6.Abducens 7.Facial 8.Vestibulocochlear 9.Glossopharyngeal 10.Vagus 11.Acessory 12.Hypoglossal
12 cranial nerves supply what?	head and neck (with exception of the vagus nerve- X)
spinal cord # and locations	31 pairs of spinal nerves; 8 cervical-neck; 12 thoracic-chest; 5 lumbar-abdominal; 5 sacral-pelvic; 1coccygeal-tailbone
Cauda equina	horse’s tail-thick bundle of elongated nerve roots at the lower vertebral canal
Cranial nerve I	olfactory-smell
Cranial nerve II	optic-sight
Cranial nerve III	oculomotor-movement of eyeball, focusing, and change in pupil size
Cranial nerve IV	Trochlear-movement of eyeball
Cranial nerve V	Trigeminal-Sensations from face, teeth, and tongue; movement of jaw, chewing muscles
Cranial nerve VI	Abducens-movement of eyeball
Cranail nerve VII	Facial-taste buds at the front of the tongue; movement of facial muscles, secretion of saliva and tears
Cranial nerve VIII	vestibulocochlear-hearing, balance, and posture
Cranial nerve IX	Glossopharyngeal-taste buds at the back of the tongue; swallowing and secretion of saliva
Cranial nerve X	Vagus-visceral sensations; visceral muscle movement (80% parasympathetic)
Cranial nerve XI	accessory-swallowing and head and neck movements
Cranial nerve XII	hypoglossal-speech and swallowing
Gray matter in spinal cord	neuron cell bodies
Central canal in spinal cord	cerebrospinal fluid (CSF)
White matter in spinal cord	myelinated axons
Anterior, posterior, and lateral columns of gray matter	divides the white matter into 3 areas called funiculi (posterior lateral, anterior)
Funiculi	nerve tracts are located in the 3 funiculi; tracts are either ascending or descending;name of most tracts indicates a. funiculus in which the tract is located b. location of its cells of origin c. level of destination
2 ascending funiculi tracts	anterior spinothalamic, lateral spinothalamic
anterior spinothalamic	ascending funiculi tract that conducts sensory impulses for crude touch and pressure
lateral spinothalamic	ascending funiculi tract that conducts pain and temp impulses
2 descending funiculi tracts	anterior corticospinal, lateral corticospinal
anterior corticospinal	descending funiculi tract that conducts motor impulses from the cerebrum to spinal nerves and outward through anterior horns for coordinated movements
lateral corticospinal	descending funiculi tract that conducts motor impulses from the cerebrum to spinal nerves through anterior horns for coordinated movements
Reflex arc	simplest type of sensory-to-motor nerve pathway
Reflex arc consists of	receptor (detect stimulus), sensory neuron (transmits a nerve impules to the CNS, and center (usually involving an interneuron)
Refex arc receptor and function	the portion of a dendrite or a specialized receptor cell in a sensory organ; sensitive to specific type of stimulus
Reflex arc Sensory (afferent) neuron and function	dendrite, cell body, and axon; transmits impulse from receptor to the CNS
Reflex arc interneurons description and function	dendrite, cell body, and axon of a neuron within the brain or spinal cord; serves as processing center; conducts impulse from sensory neuron to motor neuron
Reflex arc motor (efferent) neuron descritption and function	dendrite, cell body, and axon; transmits impulse from CNS out to an effector
Reflex arc effector description and function	a muscle or gland outside the nervous system; responds to stimulation by motor neuron and produces a reflex or physiological response
Blood brain barrier	tight jxn between endothelial cells lining the capillaries; cells surrounded by foot processes by the astrocytes
Electroencephalogram	graphic record of the evoked activity being emitted from neurons within the brain
4 EEG’s	alpha, beta, theta, delta
Alpha waves	8-12 waves/sec; parietal and occipital lobes; awake, relaxed, eyes closed. Increased blood sugar and corticoids and elevated body temperature increase the incidence of alpha waves
Beta waves	13-25 waves/sec; frontal lobes; visually orientating or thinking
Theta waves	5-8 waves/sec; temporal and occipital lobes; common in newborn infants and adults experiencing sever emotional stress
Delta waves	1-5 waves/sec; cerebrum; infants and sleeping adults; presence in awake adults is abnormal
Neurological assessment	deviation from normal EEG patterns are clinically significant in diagnosing trauma, mental depression, hematomas, and various diseases, such as tumors, infection, and epilepsy
Brain death (4 points)	unresponsive, absence of non-spontaneous unassisted respiration for three minutes, absence of CNS reflexes and fixed dilated pupils, a flat EEG for at least 10 minutes
Description of CSF	slightly alkaline solution containing more sodium, chloride, and magnesium ions than blood plasma, but less calcium, potassium, and glucose. In addition, CSF contains some proteins, urea, and leukoctyes.
Formation of CSF	CSF is continuously produced within the blood at specialized capillaries, called choroids plexuses, along the roofs of the ventricles of the brain. More CSF is formed by ependymal cells lining the ventricles and central canal.
Normal CSF fluid pressure	10 mm Hg
Pathway of flow of cerebrospinal fluid (CSF)	Lateral ventricles, interventricular forament (of Monro), Third ventricle, Cerebral aqueduct (of Sylvius), Fourth ventricle, subarachnoid space, reabsorption at the Arachnoid villi
Functions of CSF	Cushions the brain, allows for exchange of nutrients and wastes within nervous tissue, buoys the brain up
Hydrocephalus	abnormal accumulation of CSF in the ventricles and subarachnoid or subdural space. It may be caused by excessive production of or blocked flow of CSF. Hydrocephalus frequently cuases the cranial bones to thin and the cerebral cortex to atrophy.
Lumbar puncture	withdrawal of CSF from the subarachnoid space in the region of the lumbar vertebrae
Hydrocephalus	characterized by excess fluid in the cranial vault, subarachnoid space, or both. May occur at any stage of life.
Acute hydrocephalus	develops in a couple of hours in persons who hav sustained head injuries
Idiopathic or normal-pressure hydrocephalus	can occur where the CSF volume increases, but the pressure may or may not incease
Types of hydrocephalus	noncommunicating and communicating
Noncommunicating hydrocephalus	obstruction of CSF flow between ventricles; caused by congenital abnormality, aqueduct stenosis, compression by tumor
Communicating hydrocephalus	impaired absorption of CSF (caused by infection with adhesions, high venous pressure in sagittal sinus, head injury) or increased CSF secretion (caused by secreting tumor (choroid plexus)
Pathophysiology of hydrocephalus	obstructed CSF is under pressure, causing atrophy of the cerebral cortex and degeneration of the white matter tracts, there is selective preservation of gray matter.
Clinical manifestations of hydrocephalus	headache, vomiting, altered vital signs, deep coma. In congenital hydrocephalus in infants the cranial circumference is enlarged
Sleep stages	relaxation-alpha, non-REM, and REM
NonREM	Slow sleep, S state, quiet sleep
REM	active sleep, fast sleep, D state
Autonomic nervous system effector organs	cardiac muscle, smooth muscle, visceral organs and glands
Divisions of the autonomic nervous system	1)sympathetic division 2) parasympathetic division
Sympathetic division	prepares the body for intense physical activity in emergencies through adrenergic effects
Parasympathetic division	opposite to those of the sympathetic division (rest or digest)
Neurotransmitters of sympathetic and parasympathetic divisions	sympathetic- norepinephrine; parasympathetic-acetylcholine
Anatomical origin of sympathetic division	thoracic and lumbar regions (T1 to T12 and L1 to L2 or 3)
Anatomical origin of parasympathetic division	cranial and sacral regions (cranial nerves 3,7,9,10 (80% comes from 10)
Three effector organs in sympathetic division that norepinephrine is not used as the neurotransmitter	sweat glands, smooth muscles in blood vessels going to skeletal muscles, and the adrenal medulla
Similarities between para/sympathetic divisions	1. Preganglionic neurons are myelinated; postganglionic are non-myelinated 2. Efferent outlow divided into pre and post ganglionic neurons 3. Pre ganglionic neurotransmitter is actylcholine
Differences between para/sympathetic divisions	sympathetic-short preganglionic neuron, long postganglionic neuron; parasympathetic- long preganglionic neuron and short postganglionic neuron
Cholingeric receptors	nicotinic and muscarinic- mumbrane receptor proteins located on autonomic postganglionic neurons or on effector organs that are regulated by acetylcholine or other molecules with similar activity
Nicotinic receptors	located at the ganglia in both sympathetic and parasympathetic divisions
Muscarinic receptors	located on all effector organs innervated by ostganglionic neurons of the parasympathetic division
Cholinergic	all preganglionic autonomic neurons and all postganglionic parasympathetic neurons are cholinergic- they use actetylcholine as a neurotransmitter
Nicotine derived from	tobacco
Muscarinie derived from	some poisonous mushrooms
Antimuscarinic agent	atropine
Muscarinic stimulants	acetylcholine, carbachol, methacholine, and bethanechol
Adrenergic receptors	membrane receptor proteins located on autonomic effector organs that are regulated by catecholamines (epi or norepi). Two types: alpha and beta
Alpha 1 tissue location	smooth muscles
Alpha 1 efect	stimulation of smooth muscle: vasoconstriction, uterine contraction, dilation of pupil, intestinal sphincter contraction, and pilomotor contraction
Beta 1 tissue	cardiac
Beta 1 effect	stimulation of cardiac muscle: increase in heart rate and force of contraction
Beta 2 location	smooth muscle
Beta 2 effect	inhibition of smooth muscle: vasodilation, uterine relaxation, intestinal relaxation, bronchodilation
Alpha 1 stimulants and degree	norepinephrine stimulates more than epinephrine
Beta 1 stimulants and degree	norepinephrine and epinephrine are about equal
Beta 2 stimulants and degree	epinephrine is much stronger than norep
Isoproterenol	a synthetic catecholamine stimulates mainly beta 2 receptors stronger than alpha 1 receptors.
G-proteins	all adrenergic receptors act via G-proteins
Alpha receptor stimulators cause	vasoconstriction and are used as decongestants
Alpha receptor blockers are used to	lower high blood pressure
Beta receptor stimulators are used to	stimulate the heart and cuase bronchodilation
Beta blockers are used to	slow the heart rate
Mechanoreceptors	detect mechanical defomation of the receptor or the cells adjacent to the receptor. Ex: touch, deep pressure, hearing, equilibrium, arterial pressure
Thermoreceptors	detect changes in temperature, some detecting cold and others detecting warmth. These receptors may be stimulated by changes in metabolic rate.
Nociceptors	pain receptors which detect damage in the tissues, whether it is physical or chemical damage
Electromagnetic or photoreceptors	detect light on the retina of the eye
Chemoreceptors	detect taste in mouth (sweet, salt, sour, and bitter), smell in the nose, oxygen and carbon dioxide levels in the blood
Sensory receptors adaption	adapt either partially or completely to their stimuli after a period of time
Tonic receptors	do not adapt at all or adapt slowly (muscle stretch receptors)
Phasic receptors	adapt rapidly-usually no longer responding to a maintained stimulus, but when the stimulus is removed, the receptor typically responds with a slight depolarization called the off response (watch, rings, clothing)
Pain threshold in people	there is a uniformity in the pain threshold for all people. People are not more or less sensitive to pain. People react differently to pain. Stoic people react far less intensely than do more emotional people.
Pain	protective mechanism that brings to conscious an awareness that tissue damage is occurring or is about to occur
Three types of pain	cutaneous, deep pain, visceral pain
Cutaneous pain	localized upon the surface of the body; pricking, sharp, burning—usually occurs first, short duration; can be localized or diffuse; referred to as fast pain (30m/s)—A-delta myelinated fibers
Deep pain	from muscles, tendons, and joints
Visceral pain	from visceral organs; both deep pain and visceral pain are usually poorly localized; dull, aching, nauseous, throbbing—occurs 2nd, persists longer; both are conducted by B neurons, which are unmyelinated and slow (1-12m/s)—C fibers
Damage cells	protaglandins, bradykinin, substance P, Glutamate
Prostaglandins	a special group of fatty acid derivaties that are cleaved from the lipid bilayers of plasma membranes
Bradykinin	activated by enzymes released from damaged cells
Substance P	pain neurotransmitter
Glutamate	pain neurotransmitter
analgesic system	CNS contains a neuronal system that suppresses pain.
endorphins and enkephalins	chemicals the body releases in resonse to outside stimuli like exercise or stress
2 locations where pain may be blocked	periaqueductal gray matter (surrounding the cerebral aqueduct) and in the reticular formation, where they block (via presynaptic inhibition) the release of substance P
Chronic pain	occurs in absence of tissue injury. May result from damage within the pain pathways in the peripheral nerves or in the CNS. Abnormal chronic pain is sometimes referred to as neuropathic pain
Action of Aspirin, acetaminophen, and ibuprofen	diminish pain by inhibiting prostaglandin production and release
function of opiate drugs such as codeine and morphine	act directly on pain centers in the brain
referred pain	not always felt over the organ from which it's derived (heart pain felt in left arm
2 mechanisms of referred pain	1)Embryonic origin of the organ 2)Cross over of first order neurons with second order neurons in the spinal cord
Epilepsy	a chronic disorder resulting from sudden, uncontrolled discharge of activity by neurons in the brain (seizure)
manifestations of seizure activity	loss of consciousness, tonic and/or clonic muscle contraction which can be either generalized or localized
clonic muscle contraction	repeated, rythmic contractions (seizures)
causes of epilepsy	hyperglycemia, febrile disorders, head injury, drugs, birth trauma, brain tumors, stroke, metabolic disorders
drugs used to treat epilepsy	phenytoin, phenobarbital, and valproate
alzheimer's disease symptoms	trouble remembering recent events, loss of memories of the past, confusion, forgetfulness, hallucination, paranoia, vioent changes in mood
neural structural changes from alzheimer's disease	1)great loss of neurons in specific regions of the hippocampus and cerebral cortex 2)plaques of abnormal proteins deposited outside neurons 3)tangled protein filaments with neurons