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Nervous Systerm
BYU PdBio 305 Rhees Nervous System
| 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 |
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