fdjksl afdjs klejfsieofwjnervous system the body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems three critical features of the nervous system They receive input from the surrounding world. They process the info from the surroundings. They initiate responses to the internal and external environments, when necessary. neuron a nerve cell; the basic building block of the nervous system dendrites Branchlike parts of a neuron that are specialized to receive information. cell body Largest part of a typical neuron; contains the nucleus and much of the cytoplasm axon the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands glial cell cells in the nervous system that support, nourish, and protect neurons nerves bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs how many neurons die everyday? 9,000 When neurons die can they be replaced? no what can kill neurons? alcohol intake, inhaling gas fumes neurons are what kind of cell eukaryotic what does the cell body contain nucleus, mitochondria, endoplasmic reticulum, and so on What does a dendrite do? receives information what does the axon do? carries impulses away from the cell body what does the cell body do? process information sciatic nerve nerve extending from the base of the spine down the thigh, lower leg, and foot How many more glial cells are there than neurons? 9x Do glial cells divide? yes glial cells act as a barrier for harmful things entering the brain blood brain barrier Blood vessels (capillaries) that selectively let certain substances enter the brain tissue and keep other substances out how is the blood brain barrier broken down hypertension, radiation, some infectious organisms sensory neurons neurons that carry incoming information from the sensory receptors to the brain and spinal cord. stimulations like temp, touch, taste, smell, light or sound motor neurons neurons that carry outgoing information from the brain and spinal cord to the muscles and glands Interneurons neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs. peripheral nervous system network of sensory cells modified to receive info from the environment and motor pathways that transmit signals to effectors, the muscles and glands capable of responding to that stimulus sensory pathway nerves coming from the sensory organs to the CNS consisting of afferent neurons motor pathways In the peripheral nervous system, common routes by which motor nerve impulses are transmitted. somatic nervous system the division of the peripheral nervous system that controls the body's skeletal muscles (voluntary) autonomic nervous system the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms. (involuntary) sensory neurons alert the brain of a stimulus motor neurons help the brain to execute a response reflex signal that skips the brain, and goes to stimulate the motor neuron. direct sensory response autonomic nervous system helps us with homeostasis sympathetic nervous system the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations parasympathetic nervous system the division of the autonomic nervous system that calms the body, conserving its energy dendrites recieve signals from external stimuli two ways dendrites receive stimuli through motor neurons and interneurons connecting with other neurons or directly from external stimulus resting potential of neuron its stable, negative charge when the cell is inactive action potential of neuron a very brief shift in a neuron's electrical charge that travels along an axon resting potential is produced as proteins within the neurons plasma membrane pump sodium ions out of the cell and potassium ions into the cell what ion goes into the cell potassium what ion goes out of the cell sodium how does the pumping of ions affect the charge of the cell? more positive on the outside more negative on the inside greater positive charge out of the cell makes the cell polarized when stimulated dendrites briefly open ion channels made of proteins which allow charged ions down the concentration gradient concentration gradient A difference in the concentration of a substance across a distance. when ion channels open the negative charge inside the cell is temporarily changed either decreasing or increasing changes in the cells electrical charge converge from the dendrites to the cell body when charges converge that is called action potential terminal buttons Small knobs at the end of axons that secrete chemicals called neurotransmitters axon terminals (terminal buttons) doe what i response to action potential release contents of vesicles, small sacks of chemicals inside the axon terminal into the space between cells which can influence nearby cells myelin sheath A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next. as the action potential moves down the axon ion channels allow positively charged ions to rush in changing the charge to positive. other ion channels allow positively charged ions to rush out what restores the action potential ion channels letting the influx of positively charged ions to rush put Where are ion channels concentrated in the gaps in the myelin sheath fatty myelin is what color white fatty myelin shows up as white when tightly packed together regions of the brain with many cell bodies and dendrites appear what color gray multiple sclerosis myelin sheath destruction. disruptions in nerve impulse conduction little myelin causes the neurons to lose its ability to conduct electrical impulses which makes it harder for the brain to send signals to muscles synapse the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron at a synapse and neurons interacts with another cell What happens at a synapse? When a nerve impulse reaches the synapse at the end of a neuron, it cannot pass directly to the next one. Instead, it triggers the neuron to release a chemical neurotransmitter. The neurotransmitter drifts across the gap between the two neurons. sacs called vesicles release neurotransmitters into the synaptic cleft synaptic cleft The narrow gap that separates the presynaptic neuron from the postsynaptic cell. what happens when the action al potential reaches the axon terminal? little sacks called vesicles merge with axon cell membrane axon cell membrane presynaptic membrane the vesicles open and release chemicals called neurotransmitters neurotransmitters send a signal to the cell receiving the signal after sending a signal to a cell the neurotransmitters diffuse away and binds to nearby receptor sites after neurotransmitters diffuse the gates open in the post synaptic cell membrane and the signal enters the post synaptic cell after the signal enters a new neurotransmitter is released from the post synaptic cell receptors and is recycled or broken down what are neurotransmitters broken down by enzymes found in the synaptic cleft when a postsynaptic cell is a muscle cell it contracts when a postsynaptic cell is a gland it secretes how do neurotransmitters affect the neuron by causing it to fire on its own action potential or receives the likelihood of it firing on its own action potential what a neurotransmitter does to a neuron is decided by receptor the ability for neurons to not fire helps with filtering overwhelming sensory info such as a concert Acetylcholine A neurotransmitter that enables learning and memory and also triggers muscle contraction Acetylcholine is released by motor neurons at the point where they synapse with muscle cells Botulinum toxin an acetylcholine antagonist; prevents release by terminal buttons. most toxic substance known what does botox do blocks release of acetylcholine so less contractions in muscles =less wrinkles glutamine involved with learning and memory, more sensitive to glutamine, better memory and learning dopamine influences movement, learning, attention, and emotion. loss of is responsible for parkinson's. chief of happiness serotonin Affects mood, hunger, sleep, and arousal who makes serotonin more? men cocaine a powerful and addictive stimulant, derived from the coca plant, producing temporarily increased alertness and euphoria. tricks pleasure center in brain and binds with presynaptic membrane where dopamine is usually reabsorbed from the synaptic cleft. blocks reuptake sites dopamine remains in cleft repeatedly stimulating it prozac and zoloft block serotonin from being reabsorbed and recycled by presynaptic cells which prolongs it affect Selective Serotonin Reuptake Inhibitors (SSRIs) a group of second-generation antidepressant drugs that increase serotonin activity specifically, without affecting other neurotransmitters morphine and heroin mimic endorphins and bind to receptor sites. in high doses gives endorphins rush which causes euphoria. slows down respiratory rate and can be fatal nicotine mimics acetylcholine by binding to the same receptors and release adrenaline and other stimulating chemicals. rapid surges the rapid depletions of these chemicals make smokers want another cigarette drugs become addictive because the body's think that there is more natural amounts of usual neurotransmitters. reduces sensitivity to drugs, needing more to have the same reaction DRD4 gene that encodes a certain class of dopamine receptor. It can be mutated for those seeking sensation, altering the mesolimbic pathway and the way sensations are rewarded caffeine a mild stimulant found in coffee, tea, and several other plant-based substances cellular waste products takes form of a variety of molecules such as adenosine adenosine when binds with receptor reduces the likelihood of a neuron initiating an action potential as more adenosine binds with more receptors we feel tired when we sleep cellular waste products are reabsorbed and recycled effects of alcohol slowed down reactions slurs speech by blocking receptors for glutamate, provides buzz by blocking dopamine reuptake, blocks pain by stimulating the release of endorphins, increases feeling of happiness by modifying the efficiency of serotonin receptors muscles generate force through contraction skeletal muscle is attached to bones by connective tissue and is controlled by individual neurons attached to each muscle fiber cardiac muscles causes the heart to pump blood blood through the body smooth muscle, involuntary, surrounds blood vessels and many internal organs which help to move blood, move food through digestive system myofibrils cylindrical organelle within muscle cells that can contract; contains repeating units, called sarcomeres in which the contraction takes place Sarcomere the fundamental unit of muscle contraction , made of actin myosin actin protein of muscle tissue; makes up the thin filaments myosin protein of muscle tissue, making up the thick filaments muscle fiber contraction Results from a sliding movement where the actin and myosin filaments merge using ATP. Globular portions of the myosin filaments can form cross-bridges with actin filaments. Reaction between actin and myosin filaments generates the force of contraction. First step of sarcomere contraction detach, link between myosin and a parallel action filament is broken as a molecule of ATP bonds to myosin Second step of sarcomere contraction reach, as the atp breaks down, energy released alters the shape of the myosin into a higher energy shape and myosin now reaches farther down the actin filament Third step of Sarcomere contraction reattach, the myosin reattaches to the actin filament at this new location Fourth step of Sarcomere contraction pull back, the myosin then snaps back to its original shape, pulling the actin filament as it does so and shorting the fiber relaxed sarcomere Actin & Myosin myofilaments lie side by side contracted sarcomere the Z lines are close together duration between contraction and relaxation is called twitch fast twitch muscle fibers that react quickly and fatigue quickly slow twitch type of muscle that contracts slowly and is fatigue resistant Oxytocin peptide hormone, produced in neurons within the hypothalamus and released by the posterior pituitary, influences trust in others, increases the social attachments, directs the ejection of breast milk, and contractions in the uterus during childbirth synthesis site of oxytocin hypothalamus target tissues of oxytocin uterus and mammary glands effect of oxytocin Effects uterus - uterine contractions during labor, direct myometrium, other effects are on limbic system in both men and women increased by touch - reflects on bonding and trust hormones chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues two systems for carrying out communication nervous and endocrine endocrine system the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream endocrine cells produce regulatory hormones target cells cells that have receptors for a particular hormone endocrine glands Glands of the endocrine system that release hormones into the bloodstream endocrine gland examples pituitary, thyroid, parathyroid, adrenal, pineal hormones help regulate homeostasis pheromones Chemical signals released by an animal that communicate information and affect the behavior of other animals of the same species. such as sexual reproduction and territory marking step one of how a hormone affect a certain cell signal is sent by a hormone being released from a gland step two of how a hormone affects a certain cell signal is received, although the hormone has no effect on most tissues it comes in contact with, cells with the right receptor in their cytoplasm or on their plasma membrane receives the signal step three of how a hormone affects a certain cell cell responds, hormone binds to receptor, causes response in target cell, can be change in gene expression in nucleus, can cause cell to start or stop producing a certain protein, alter rate of producing protein amines hormones adrenaline, hormones that are synthesized from single amino acids polypeptide hormones insulin and glucagon, chains of amino acids steroid hormones estrogen and testosterone, lipids lipid Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen. most amines and polypeptide hormones are — while lipids are not water soluble amines and polypeptide hormones — pass through memebrane cannot lipids —pass through membranes can amines and polypeptide hormones bind to receptors embedded within the cell membrane which can influence inside the cell steroids hormones bind to receptors within the cytoplasm or nucleus of the cell, always passes into nucleus once a steroid is in the nucleus it binds to DNA, influencing gene expression paracrine receptors target cell receptors for a specific hormone can be nearby hormones secreted by glands in one part of the body are able to regulate cell function in another part of the body Prostaglandins Modified fatty acids that are produced by a wide range of cells. dilation or construction of blood vessels and affecting tissue inflammation what does asprin do Inhibits prostaglandins, decreases inflammation, and slows transmission of pain to site of injury Hypothalamus underside of brain, functions as liaison between the nervous and endocrine systems and it receives input from neurons throughout the brain and rest of body. sends out appropriate hormones to regular nearly every aspect of the organisms physiology, including body temp, hunger. thirst, and water balance pituitary gland The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. posterior pituitary gland also known as the neurohypophysis; it is made up of nervous tissue/neurons and stores and secretes 2 hormones made by the hypothalamus (oxytocin and ADH); it is controlled by action potentials from the hypothalamus antidiuretic hormone (ADH) influences the absorption of water by kidney tubules anterior pituitary produced many hormones such as TSH, LH, FSH, prolactin, ACTH Thyroid Stimulating Hormone (TSH) causes thyroid to produce thyroxine, important in cellular respiration Follicle-stimulating hormone (FSH) stimulates development of follicles in ovaries and sperm maturation Lutenizing hormone (LH) triggers ovulation and stimulates testosterone production, works with FSH prolactin stimulates mammary glands to produce milk Adrenocorticotropic hormone (ACTH) Stimulates adrenal glands to produce cortisol and other stress related hormones Corticotropin-releasing hormone (CRH) Promotes secretion of adrenocorticotropic hormone (ACTH) growth hormone several effects, stimulating liver to release chemicals that spur growth of bones, cartilage, and other tissues excessive production of growth hormone during childhood can cause extreme growth called gigantism increased exposure to growth hormone in adulthood results in hands, face, feet growing unusually absence of growth hormone dwarfism how is pituitary dwarfism treated if caught early? shots of human growth hormone pineal gland secretes melatonin regulates sleep cycles thyroid gland releases thyroxine, influences the rate and efficient of cellular metabolism, regulates calcium levels in blood parathyroid glands regulate calcium levels in blood adrenal glands release adrenaline and cortisol (prepares body for action), regulate organisms response to stress. sit right above kidneys. pancreas releases insulin and glucagon, maintains blood glucose levels wishing a narrow range gonads release the sex steroids, including testosterone, estrogen, and progesterone, responsible for numerous physical, behavioral, and emotional features, including much sexual behavior, development, and growth Under active thyroid fatigue and weight gain overactive thyroid jitteriness, rapid heartbeat, weight loss, irritability when iodine intake is low, the thyroid is unable to produce thyroxine which causes thyroid to swell Calcitonin Lowers blood calcium levels insulin A hormone produced by the pancreas or taken as a medication by many diabetics negative feedback A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation. positive feedback Feedback that tends to magnify a process or increase its output. endocrine disrupters Chemicals that disrupt normal hormone functions Polychlorinated biphenyls (PCBs) A group of industrial compounds used to manufacture plastics and insulate electrical transformers, and responsible for many environmental problems. Phthalates found in cosmetics, deodorants, and many plastics used for food packaging, children's toys, and medical devices. Cause kidney & liver damage, cancer, and low sperm counts. Bisphenol A (BPA) a substance widely used in plastics and to line food and drink cans, which has raised health concerns because it is an estrogen mimic endocrine disrupters effect on mammals reproductive harm endocrine disrupters effect on fish reproductive functioning endocrine disrupters effect on invertebrates defective shells, masculinization of female genitalia, reducing fertility oxytocin posterior pituitary, uterus, breast, brain, reduce stress, more trusting "love hormone" antidiuretic hormone (ADH) posterior pituitary, kidneys, water retention in kidneys Thyroid Stimulating Hormone (TSH) anterior pituitary, thyroid, stimulates production of thyroxine, important in cellular respiration Follicle-stimulating hormone (FSH) anterior pituitary, ovaries, testes, stimulates ovary development and sperm maturation prolactin anterior pituitary, mammary glands, milk production growth hormone anterior pituitary, liver and other organs, stimulates release of chemicals that spur growth of bones, cartilage, and other tissues cortisol and adrenaline adrenal glands, smooth, cardiac, skeletal muscle, blood vessels, cell throughout body, imitates response to stress, regulates response to long term stress melatonin pineal gland, brain, regulate sleep cycle thyroxine thyroid, cells throughout body, influenced metabolic spew and efficiency calcitonin and parathyroid hormone thyroid, bones, causes bones to pick up excess calcium in blood insulin pancreas, liver, adipose tissue, skeletal muscle, take up glucose in blood which reduces its level glucagon pancreas, liver, adipose tissue, concert stored glycogen into glucose estrogen, testosterone, progesterone gonads, cells uterus, breasts, balls, puberty, pregnancy, sperm production, egg production heritable sensory autonomic neuropathy condition in which afflicted individual cannot feel pain sensory neurons affected by skin and joints affected by syphilis Interneurons are affected by parkinsons motor neurons are affected by polio Oligodendrocytes Type of glial cell in the CNS that wrap axons in a myelin sheath. Microglia Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system astrocyte release gliotransmitters by expcytosis to send signals to neighboring neuron connectomes Map of the network of connections between neurons in the human brain resting potential -70 mV action potential +30 mV (depolarized) Channelopathies diseases and disorders that are the result of ion channel dysfunction Tetrodotoxin -Poisoning can result from ingestion of poorly prepared puffer fish (exotic sushi) -Highly potent toxin that binds fast voltage-gated Na+ channels in cardiac and nerve tissue, preventing depolarization - blocks action potential without changing resting potential (same mechanism as Lidocaine) -Causes nausea, diarrhea, paresthesias, weakness, dizziness, loss of reflexes. -Treatment is primarily supportive. epilepsy potassium channel mutations, muscle weakness the synapse excitatory neurotransmitters chemicals released from the terminal buttons of a neuron that excite the next neuron into firing inhibitory neurotransmitters chemicals released from the terminal buttons of a neuron that inhibit the next neuron from firing GABA An inhibitory neurotransmitter in the brain. caffeine — glutamine and — GABA activity increases, decreases Alcohol — GABA activity and — Glutamate activity increases, decreases functions of muscle generate movement, force, heat, homeostasis 2 mutates copies of them upstairs gene causes excess muscle build up muscle is composed of bundles of muscle fibers bundles of muscle fibers are composed of muscle fibers muscle fibers are composed of myofibrils myofibrils are composed of actin and myosin actin and myosin are composed of sarcomere slow fiber muscle is dark mest fast fiber muscle is light meat motor unit A motor neuron and all of the muscle fibers it innervates rigor mortis stiffness after death caused by lack of ATP, muscle remains in a state of contraction acromegaly abnormal enlargement of the extremities during adulthood when exposed to excess growth hormone Addison Disease low levels of cortisol, autoimmune disease, depression, dizziness, low blood glucose, low blood pressure chronic stress excess cortisol, high blood glucose, obesityfdwkqfejifijeoiefowojk
234
