A&P 1 test 3

smooth muscle compared to skeletal

-thin filaments attach to dense bodies -electrical junctions between cells (in single unit type) -scanty sarcoplasmic reticulum and no t-tubules -most Ca from ECF -audtorhythmicity (single unit type) - responsive to autonomic nervous system -very slow responding (contracting and relaxing) - low energy (atp) requirement. high fatigue resistant -regenerates well unlike others

Delayer-onset muscle soreness (DOMS)

pain, stiffness, and tenderness felt from several hours to a day after strenuous exercise. associated with microtrauma to the muscles with disrupted z disks, myofibrils, and plasma membranes; and with elevated levels of myoglobin creatine kinase, and lactate dehydrogenase in the blood. happens when you have a tough workout and you are sore after.

memory trace

physical bias of memory is a pathway through the brain (memory trace). in which synapses have been formed or existing synapses have been modified to make transmission easier. synapses are not fixed for life, in response to experience. they can be added, taken away, or altered to make transmission easier or harder.

synaps

point where fiber meets any target cell

what are the 4 characteristics of local potentials?

1. Graded, (they vary in magnitude or volume) according to strength of stimulus. 2. Decremental (they get weaker as they spread from the point of stimulation.) 3. Reversible (if stimulation ceases, cation diffusion out of cell quickly returns the membrane voltage to its resting potential) 4. Excitatory OR Inhibitory (depolarization or hyperpolarization)

tendon reflex

response to excessive tension on the tendon, inhibits alpha motor neurons to the muscle so the muscle does not contract as strongly. serves to moderate muscle contraction before it tears a tendon or pulls it loose from the muscle or bone. also function when some parts of a muscle contract more than others. inhibits muscle fibers connected with overstimulated tendon organs so their contraction is more comparable to the other muscles. spreads the workload more evenly which helps in movements such as maintaining a steady grip on a tool.

procedural memory

retention of motor skills, how to tie shoe, play instrument, drive car/bike, .

sarcoplsmic reticulum

reviser of calcium ions, has channels in its membrane that open to release calcium into the cytosol, when calcium floods the cytosol the muscle contraction process begins.

Claudius Galen

roman physician, said the brain pumps "psychic pneuma" through hollow nerves to make muscles jump

isometric

same length. not just a prelude to movement, isometric contraction of antagonistic muscles at a single joint is important in maintaining joint stability at rest, is also what keeps our bodies from sinking into a heap on the floor.

isotonic

same tension. change in length without change in tension. begins with internal tension builds to the point that it overcomes resistance, and muscle now shortens to move load and maintains same tension. two forms include concentric and eccentric

synaptic transmission

some neurotransmitters are excitatory and some are inhibitory and some can do both depending on what kind of receptor that postsynaptic cell has. some open ligan-gated ion channels and others act through second messengers.

oligodendrocytes

sorta resemble an octopus; they have bulbous body with many arms. each arm reaches out to a nerve fiber and spirals around it like electrical tape. this wrapping is called a myelin sheath. insulates the nerve fiber from ECF

sensory (afferent) neurons

specialize in detecting stimuli such as light, heat, pressure, chemicals, and transmit info about them to the CNS. these neurons begin in almost every organ and end in the centeral nervous system. AFFERENT means signal conduction TWARD the central nervous system. some receptors such as pain and smell receptors are neurons themselves, but hearing and taste the receptor is a separate cell that communicates directly with a sensory neuron.

what are the 3 layers of the meninges superficial to deep?

1. dura mater 2. arachnoid mater 3. pia mater

what are the types of transport

1. fast axonal transport 2. slow axonal transport

what determines the strength of a twitch?

1. how stretched the muscle was before stimulation. 2. twitches are weaker as a muscle fatigues 3. twitches vary with temperature, if warmed up, muscle contracts strongly (myosin heads move faster) 4. varies with muscle state of hydration, affects the spacing between thick and thin filaments and therefor the ability to make myosin-actin cross bridges) 5. twitch strength varies with stimulus frequency.

Whats inside a muscle fiber

scarcolemma (plasma membrane), sarcoplasm (cytoplasm), myofibrils (long protein chords in the sarcoplasm), satellite cells , sarcoplamic reticulum (endoplasmic reticulum, inside there are sometimes terminal cisternae), transverse(t) tubules( in sarcolemma, penetrate through cell and to the other side, and it associated with cisternae along side of it) , and mitochondria

motor (efferent) neurons

send signals to muscle and gland cells, the effectors. called motor neurons because most of them lead to muscle cells and efferent neurons to signify signal conduction AWAY from the cns

what are the two kinds of nerve fibers in peripheral nervous system?

sensory (afferent) fibers- fibers carrying signals from sensory receptors to the CNS. composed of only afferent fibers, and are rare include nerve fibers for smell and vision. motor (efferent) fibers- fibers carrying signals from the CNS to the muscles and glands. both can be classified as somatic or visceral. and as general or special depending on the organ they innervate. carry only efferent fibers,but most are mixed fibers

Ascending tracts

sensory info up the cord,

what are the three kinds of memory

short term immediate long term

presynaptic neuron

signals arrive by way of this neuron. which releases a neurotransmitter. may synapse with a dendrite, soma, or axon of postsynaptic neuron forming a axodendritic, aomatic, or axoaxonic synapse. a neuron can have an enormous amount of synapses.

somatic reflexes

skeletal muscle reflexes because involves somatic nervous system. also called spinal reflexes. but this is misleading because spinal reflexes are not exclusively somatic and some somatic reflexes are more mediated by the brain than the spinal cord. employ a reflex arc

What are the types of muscle tissue

skeletal, cardiac, smooth

slow twitch vs fast twitch

slow oxidatives (SO) - well adapted for endurance and fatigue resistance, so they are particularly important in muscles that support the body and maintain posture, such as erector spinae their resistance stems from their oxidative mode of ATP production. these capillaries are rich in mitochondria and myoglobin, the red pigments. the slowness of the muscle is due to the sarcoplasmic reticulum, relativly slow to release and reabsorb calcium, and a form of myosin ATPase thst is relatively slow in its ATP hydrolysis and cross bridge cycling. myoglibin are what give it the red color (red fibers)

microglia

small macrophages that develop from white blood cells celled monocytes. they wonder through CNS, putting out finger-like extensions to constantly probe the tissue for cellular debris or other problems. performs complete check-ups on the brain and spinal cord several times per day, phagocytizing dead tissue, microorganisms and other foreign matter. become concentrated in areas with damage by infection trauma or stroke.

small vs large motor units

small motor units- needed with fine control, eye movement as small as 3:1 Large motor units- strength is more important than fine control, ex. gastrocnemius in the calf as large as 1000:1

neurotransmitters

small organic molecules that are released when a nerve signal reaches a synaptic knob or varicosity of the nerve fiber, then bind to a receptor on another cell and alter that cell's physiology.

size principal

smaller, less powerful motor units with smaller slower nerve fibers are activated first, this is sufficient for deicate tasks. when more power is needed larger motor units with larger, faster nerve fibers are subsequently activated . but even when voltage remains constant, twitch strength can vary with stimulus frequency. High-makes stronger twitches.

Myocyte structure

smooth muscle myocytes have fusiform shapes wide in middle tapering on the ends, one nucleus. it is scanty and has no t-tubules, thick and thin filaments are present but no striations, sarcomeres, or myofibrils because myofilaments are not bundled and aligned with each other the way they in striated muscles, and no z disks. instead there are dense bodies that are protein plaques to replace the z disks. some of the dense bodies are associated with the inner face of the plasma membrane and others dispersed throughout the sarcoplasm. membrane- associated dense bodies of one cell are often directly across from those of another, with linkages between them so that contractile force can be transmitted from cell to cell. intermediate filaments attatch to actin filaments as well as directly to dense bodies. so movement is transferred from sarcolemma and shortens the cell.

smooth muscle varicosities

smooth muscle- myocyte has no motor end plate. insted had receptors for the neurotransmitters on its surface. vaeicosites release floods of neurotransmitters, each myocyte may respond to more than one nerve fiber. weather innervated or not smooth muscle responds to a wide variety of stimuli snd often without any electrical excitation of sarcolemma. takes even longer than cardiac and skeletal to contract and relax, but can stay contracted for a longer period of time without fatigue and not much energy expended.

smooth muscle functions

smooth muscles can propel the contents of an organ such as driving food through digestive tract or voiding urine and facies. by dilating or constricting of the blood vessels and airway. can modify the speed of airflow and maintain blood pressure and reroute blood from one pathway to another. iris regulates pupil diameter. and pilorector muscles. smooth muscle is capable of hypertrophy (cell growth) and mitosis and hyperplasia. this is how organs such as pregnant uteruses grow by the addition of new myocytes as well as enlargement of existing ones. injured smooth muscel regenerates by mitosis

depolarization

sodium cations override the negative charge inside the cell and the ICF becomes positive for a moment,

heat cramps

sodium depletion through heavy sweating alters resting membrane potential of muscle.

dendrites

soma usually give rise to it. thick processes that branch into a cast number of these. primary site for receiving signals from their neurons. some neurons only have one dendrite and some have thousands. the more dendrites a neuron has, the more information it can receive and incorporate into its decision making. provide precise pathways for the reception and processing of neural info.

reflex arc

somatic reflexes employ it. signals travel along the following pathway. 1. somatic receptors in the skin, msucles and tendons. 2. afferent nerve fibers which carry info from these receptors to the posterior horn of the spinal cord or the brain stem. 3. integrating center, point of synaptic contact between neurons in gray matter of the cord or brainstem 4. effernent nerve fibers which carry motor impulses to the msucles 5. effectors, the muscles that carry out the response. or receptor, afferent neurons, interneurons usually, efferent neurons, and effector (muscle or gland). In most reflex arcs most integrating centers have one or more interneurons, synaptic events in the integrating center determine if efferent neurons issue signals to the muscles. the more interneurons the more complex the info processing can be, but with the more synapses the longer the delay between input and output.

conduction speed of nerve

speed at which a nerve signal travels along a nerve fiber depends on two factors 1. diameter of the fiber 2. presence or non presence of myelin signal conduction occurs along the surface of a fiber, not deep within its axoplasm. large fibers have more surface area and conducts signals more rapidly than small fibers. myelin further speeds signal conduction

meninges of spinal cord

spinal cord and brain are enclosed in these three membranes. they seperate the soft tissue of the CNS from the bones of the vertebra and skull.

myelin sheath

spiral layer of insulation around a nerve fiber, formed by oligodendrocytes in the CNS and schwann cells in the PNS. consists of the plasma membrane of glial cells (20% protein and 80% lipid- including phospholipids, glycolipids, and cholesterol)

PNS Schwann cell

spirals repeadidly around a single nerve fiber, laying down up to 100 compact layers of its membrane with almost not cytoplasm between membranes. these layers are whats called the myelin sheath.

myoblasts

stem cells, fuse to produce each fiber, each myoblast contributes one nucleus.

whats the difference between tendons and ligaments

tendon- muscle to bone ligament- bone to bone

parasympathetic

tends to have a calming affect- slowing the heartbeat for example. but it stimulates digestion

length tension relationship

tension generated by a muscle, therefor the force of its contraction depends on how stretched it was at the outset . when a fiber is too short, contraction is week because sliding filaments cant go far without hitting the z-disk. when fiber is too long, (over-stretched) contraction is weak as well because not enough myosin heads can get a good grip on actin. optimum with sarcomeres is 2-2,5 nanometers long

Triad

the T-tubule and its two terminal cisterna along side it. i

synaptic plasticity

the ability for a synapse to change. synapse can be created or destroyed in as little as 2 hours.

neural integration

the ability of your neurons to process info. store it,and recall it, and make decisions

immediate memory

the ability to hold something in your mind for just a few seconds. by remembering what just happened we get a feeling for the flow of events and a sense of the present. this is what allows us to read, you must remember the words before each word in order to get the meaning of the sentence. based on reverberating circuits.

Cuada equina

the bundle that makes up the medullary cone. looks like a horse take. innervates the pelvic organs and lower limbs.

muscle fiber

the cell

what does it mean to have a polarized cell?

the cell has a net negative charge in the ICF,

resistance exercise

the contraction of muscles against a load that resists movement. ex. weightlifting. growth comes from enlargement of cells not cell division. muscle fibers synthesis and myofibrils grow thicker, well conducted muscle has more myofibrils than a poor conducted one. muscle fibers are not able to undergo mitosis but they may enlarge and split longitudinally

soma

the control center of the neuron also called the cell body or neurosoma. has an nucleus in the center with a large nucleolus.

axoplasm and membrane

the cytoplasm of a neuron and axolemma is the membrane. a neuron never has more than one axon, and some neurons in the retina and brain have none

Autorhythmic

the heart has this ability to contract rhythmically and independently. stimulation by the autinomic nervous system, can however increase or decrease the heart rate and contraction strength. cardiac muscle maintains twitches (tension) for longer 200-250 ms, giving time for the heart to expel blood. cardiac uses aerobic respiration almost exclusively. rich in myoglobin and glycogen and has especially large mitochondria occupying about 2% of muscle fibers. vulnerable to oxygen deficiency- the cardiac muscle

what are the universal characteristics of muscles?

Excitability (responsiveness)- property of all living cells but muscle and nerve cells have this trait to the highest degree Conductivity- stimulation of a muscle cell produces more than a local effect. local electric change triggers a wave of excitation that travels rapidly along the cell and initiates processes leading to concentration. Contractility- ability to shorten substantially when thy are stimulated. enables them to pull on bones and other organs to make movement. Extensibility- in order to contract muscles must be extensible, able to stretch again between contractions. Elasticity- after muscles stretch and release , it recoils to a short length, without it muscles would be too slack

Excitatory postsynaptic potential (EPSP)

any voltage changer in that direction makes a neuron more likely to fire. usually result from Na+ flowing into the cell and neutralizing some of the negative charge on the inside of the membrane.

Slow oxidative fibers

are called red muscles. chicken legs.. used for long standing. in humans small SO fibers are used in small motor units and supplied by relatively small but easily excited motor neurons. the motor units aren't as strong as the large ones but makes more precise movements instead. -abundant mitochondria -abundant myoglobin -high capillary density -aerobic respiration -high fatigue resistance -long twitches

what is muscle compartment syndrome

blood goes into compartment of the muscle, and limits blood supply, high pressure. blood doesnt go back into the lungs a d kidneys to keep "good Blood" flowing.

what are the subdivisions of peripheral nerves

break down into sensory (afferent) and motor (efferent) . sensory divides into somatic and viceral. Motor divides into visceral and somatic as well. visceral motor then divides into sympathetic and parasympathetic

excess post-exercise oxygen consumption (EPOC)

breathing hard for several minutes after strenuous exercise this process is used to meet the metabolic demand. also known as oxygen debt. its the difference between the elevated rate of oxygen consumption at the end of an exercise and the rate at rest. it occurs in part because exercise depletes your stores if ATP and carotene phosphate, oxygen is required to synthesise atp aerobically some of that atp is used to regenerate the muscle myoglobin and the liver disposes of the oxygen in disposing of the lactic acid.

facilitated zone

broader than discharge zone, it synapses with other neurons in the pool, with fewer synapses on each of them.can stimulate those neurons to fire only with the assistance of other input neurons. in other words, it facilitates the others, it has a vote on what the postsynaptic cells in the facilitated zone do, cant determine the outcome though.

nerve

bundle of nerve fibers (axons) wrapped in fibrous connective tissue. they emerge from CNS through foramina of the skull and vertebral column and carry signals to and from other organs of the body. contains ganglion inside.

what are the four regions the spinal cord is divided into? and how many spinal nerves does the spinal cord give rise to?

cervical, throacic, lumbar, and sacral and 31 pairs of spinal nerves

Resting membrane potential (RMP)

charge difference across the plasma membrane. all living cells are polarized, about -70 millivolts in an unstimulated "resting" neuron. the negative value means there are more negatively charged particles on the inside of the membrane than on the outside. we don't have free electrons in the body like in an electrical circuit. electrical currents are created instead by the flow of ions such as sodium and potassium through gated channels in plasma membrane. the channels can be opened or closed at any time by various stimuli.

Luigi Galvani

discovered "animal electricity" improvements in technology of the microscope and histological staining methods camillo golgi developed an important method for staining neurons

cross-training

endurance training does not increase muscle strength significantly and resistance training doesn't improve endurance significantly. incorporated elements of both types is whats optimal for musculoskeletal health. if muscles aren't kept up, they will become reconditioned (weaker and more fatigued)

dystrophin

enormous protein in sarcolemma and outermost filaments . links actin filaments to peripheral protein on the inner face of the sarcolemma. this leads to the fibrous endomysium surrounding the muscle fiber. when thin filaments pull on the extracellular connective tissue leading to the tendon. Problems with this protein genetically are the reason for diseases like muscular dystrophy

basal lamina

entire muscle fiber and Schwann cell of NMJ are surrounded by basal lamina, separates them from surrounding connective tissue. make of collagen and glycoprotein , it passes through synaptic cleft and almost fills it it contains acetylcholinesterase sarcolemma contains this enzyme as well. its purpouse is to break down ACh after it has stimulated the muscle cell, important in turning off muscle contraction and allowing muscles to relax.

Schwann cells or neurilemmocytes

envelope nerve fibers in the PNS. mast cases the cell winds repeatedly around a nerve fiber and produces a myelin sheath similar to oligodendrocytes in the CNS. assist in regeneration of damaged fibers.

Excitation- contraction coupling

events that link potentials on the sarcolemma to activation of the myofilaments, preparing them to contract

postsynaptic potentiation

memories lasting for a few hours such as remembering an what someone said eariler that day or an appointment that is upcoming. this process the Ca+ level in the synaptic kbob stays elevated for so long that another signal coming well after the tetanic stimulation has ceased. released an exceptionally large neurotransmitter. that is if a synapse has been heavily used in the recent past. a new cell can excite the postsynapic cell more easily (your memory may only need a slight jog to recall something)

multipolar neurons

have one axon and multiple dendrites. most common type and includes most neurons of the brain and spinal cord.

Bipolar neurons

have one axon and one dendrite. olfactory cells of the nose certain neurons of the retina, sensory neurons of the ear.

unipolar

have only a single process leading away from the soma. they are represented by the neurons that carry sensory signals to the spinal cord. also called pseudo-unipolar. they start out as bipolar in the womb. but they fuse into one

temporal summation

high stimulus frequencies say 20 to 40 stimuli each new stimulus arrives before the previous twitch is over. each twitch piggybacks the other. twitches get stronger without the muscle completely relaxing (incomplete tetanus)

threshold

minimum voltage necessary to generate an action potential in the muscle fiber. at threshold or higher a muscle causes a quick cycle of contraction and relaxation (twitch)

what is contained in a neuron's cytoplasm?

mitochondria, lysosomes, golgi, numerous incisions, extensive rough ER, and cytoskeleton.

intrafusal fibers

modified muscle fibers WITHIN a spindle gamma motor neuron- of spinal cord innervates each end and stimulates its contraction. maintains tension and sensitvety of the intrafusal fiber preventing it from going slack like an unstretched rubber band when a muscle shortens. Alpha motor neurons- spinal motor neurons that supply the extrafusal muscle fiber.

secondary afferent fibers

monitor length only, not rate of change. sensory fibers that enter the posterior horn of the spinal cord synapse on alpha motor neurons and regulate their firing. also send branches up the spinal cord to the brain. brian subconsously monitors every length and tension of nearly every skeletal muscle throughout the body.

primary afferent fibers

monitor muscle length and how rapidly it changes (very responsive to sudden body movements)

histamine

monoamine, hypothalamus, also potent vasodialater released by mast cells of connective tissue and basophils of the blood.

serotonin

monoamine, hypothalamus, limbic system, cerebellum, retina, and spinal cord. also secreted by blood platelets and intestinal cells. involved in Sleepiness, alertness, thermoregulation, and mood

epinephrine

monoamine, hypothalamus, thalamus, spinal cord, and adrenal medulla. effects are similar to norepinephrine. Mood, dreaming, walking

Dopamine

monoamine, hypothalmus, limbic system,cerebral cortex, and retina; highly concentrated in substantia nigria of midbrain, involved in elevation of mood and control of skeletal muscles

Norepinephrine

monoamine, sympathetic nervous system, cerebral cortex, hypothalamus, brainstem, cerebellum, and spinal cord; involved in dreaming, walking, and mood; excites cardiac muscle and can excite OR inhibit smooth muscle and glands depending on location.

eccentric contraction

muscle LENGTHENS as it maintains tension. Ex. setting dumbbell down. more prone to injury

indirect attachment

muscle ends conspicuously short of the bone, and the gap is bridged by a fibrous band called a tendon or ligament . Ex. calcanial tendon

what are the connective tissue components smallest to largest and deep to superficial?

muscle fiber, endomysium, perimysium, fascicles, epimysium, and fascia

myosin

in thick filament, its a protein shaped like a gold club with two chains intertwined to form a shaftlike tail and globular heads. heads are angled to the left and right with a bar zone in the center with no heads.

medullary cone

inferior to the lumbar enlargement, cord tapers to a point. a bundle of nerve roots that occupy the vertebral canal from L2-L5. the bundle is called cuada equina

synergist

muscle that aids the prime mover. two or more synergists acting on a joint can make more power than one large muscle.ex. biceps brachii

antagonist

muscle that opposes the prime mover. in some cases it relaxes to give the prime mover almost complete control of the action. most cases it just prevents the prime mover from excessive movement, joint injury ect. by limiting speed and range. Ex. triceps brachiii antagonistic pair- muscles that act on opposite sides of a joint.

Fixator

muscle that prevents a bone from moving to fit a bone means to hold it steady, allows another muscle attached to it to pull on something else. Ex. Rhomboids

prime mover (agonist)

muscle that produces most of the force during a particular joint action. ex. brachialis moving elbow

what makes a cell an electrically excitable cell?

muscles and nerves are examples of this, these cells plasma membrane exhibit voltage changes in response to stimulation

immediate energy

intense energy (100 m dash), myoglobin in a muscle fiber supplies oxygen for a limited amount of aerobic respiration, but the oxygen supply is quickly depleted. until cardiovascular and resperitory catch up, muscle uses ATP by borrowing phosphate from other molecules and transferring them into ADP two enzymes that control phosphate transfer are myokinase and creatine kinase

Contractile proteins

myosin and actin are these kind of proteins because they do the work of shortening the muscle fiber.

PNS and CNS commonalities

nerve fibers are much longer than the reach of a single glial cell si it requires many Schwann cells or oligodendrocytes to cover one nerve fiber. myelin sheath is therefor segmented. the gaps are called NODE OF RANVIER and myelin covered segments are called INTERNODES. the short segment of nerve fiber between axon hillock and first glial cell is called the initial segment. AXON HILLOCK and INITIAL SEGMENT make up the TRIGGER ZONE.

Regeneration f nerve fibers

nerve fibers of the PNS are vulnerable to cuts, crushing injuries, and other trauma. a damaged peripheral nerve fiber may regenerate but if the soma is intact and at least some neurolemma remains.

electrical potentials and currents

neural communication is based on electrophysiology like muscle excitation. cellular mechanisms for producing electrical potentials and currents

post synaptic potentials

neural integration is based on the postsynaptic potentials produced by the neurotransmitter. a typical neuron has a resting membrane potential of about -70 and a threshold of about -55mV. a neuron has to be depolarized to this threshold in order to produce action potentials voltage change in direction makes a neuron more likely to fire and is therefore called excitatory postsynaptic potential (EPSP).

Acetylecholine ACh

neuromuscular junction, most synapses of Autonomic nervous system, retina, and many parts of the brain. excites skeletal muscle, inhibits cardiac muscle, and has excitatory OR inhibitory effects on smooth muscle and glands depending on location.

relative refractory period

lasts until hyperpolarization ends, during this period, K+ channels are still open. a new stimulus tends to admit Na+ and depolarize the membrane, but K+ diffuses out through open channels as Na+ come in, and thus opposes the effect of the K+ outflow and depolarize the cell as responsive as ever.

postsynaptic neuron

neuron that responds to the presynaptic neuron.

reverberating circuit

neurons stimulate each other in a linear sequence from input to output neurons, but some of the neurons late in the path send axon collaterals back to the neurons earlier in the path and restimulate them. the stimulus lasts until one or more neurons in the circut fail to fire, or inhibitory signal from another source stops one of them from firing. can find these in diaphragm, intercostal muscles, to make you inhale. when circuit stops fireing you exhale. also involved in short term memory and may play a role in uncontrolled "storms" of neural activity that happen in epilepsy.

substance P

neuropeptide, basal nuclei, hypothalamus, cerebral cortex, small intestine, and PAIN-receptor neurons. mediates pain transmission

B-endorphin

neuropeptide, digestive tract, spinal cord, and many parts of the brain, also secreted as a hormone by pituitary; supress pain reduces perception of fatigue and may produce "runners high"

inhibitory postsynaptic potential

neurotransmitter hyperpolarizes the post synaptic cell and makes it more negative than the RMP. this makes the post synaptic cells less likely to fire. some are produced by a neurotransmitter opening ligand gated chloride channels causing chlorine to flow into the cell and make cytosol more negative. less common is to open selective K+ channels, increasing the K+ diffusing outside of the cell.

does ATP depletion cause fatigue?

no longer thought to cause fatigue the atp level in fatigued muscle is almost as great as in rested muscle.

complete tetanus

not even partial relaxation, (one fused contraction). this doesn't happen in the body because motor neurons don't fire that fast. this would be very disastrous for muscle tissue, so spinal chord prevents this from happening.

ceratine kinase

obtains phosphate from a phosphate storage molecule (ceratine-phosphate or CP), and donates it to ADP to make ATP. this fast acting system helps to maintain ATP levels while other ATP generating systems are being activated.

fast axonal transport

occurs at a rate of 20 to 400 mm/day and may be either snterograde or retrograde. -fast anterograde transport moves mitochondria: synaptic vesicles, other organelles, componants of axolemma, calcium ions, enzymes such as acetylcholisterase, small molicules such as glucose, amino acids, and nucleotides tward the distal end of axon. -fast retrograde transport- returns used synaptic vesicles and other materials to the soma and inform the soma of conditions at teh axon terminals. some pathogens exploit this process to invade nervous system. enter distal tips of axon and travel to soma by retrograde transport. ex. tetanus toxans, rabies, and herpes.

long term memory

lasts up to a lifetime, and is less limited than STM in the amout of info it can store. LTM allows you to memorize the lines of a play, the words of a fav. song, or textbook info for an exam. and on a longer scale, your name, the route to your home, childhood experiances. two forms are declaritave and procedural

interneurons (assosiaation neurons)

lie entirely within central nervous system, receive signals from many other neurons and carry out the integrative function of the nervous system. they process, store, and retrieve info and "make decisions" that determine how the body responds to stimuli. 90% of all neurons are interneurons. interneuron means they lie between and interconnect incoming sensory pathways and the outgoing motor pathways.

caveolae

little pockets in the sarcolemma to compensate for the scarcity of the SR. gated channels are opened mechanically or in response to physical disortion such as strength.

Myofibrils

long protein chords found in the sarcoplasm, 1 nanometer in diameter, contains an abundance of glycogen (starch like carbohydrate that provides energy for the cell during highly energetic exercise) and myoglobin (red-oxygen binding pigment. provides some oxygen thats is needed for oxygen)

muscular system

made of skeletal muscles only, about 600 muscles in the human body. the word muscle means little mouse

muscle tone

maintaining a state of partial contraction. the complete length-tension curve is derived from muscles isolated from an animal (frog). this maintains optimum sarcomere length and makes muscles ideally ready for action. elastic filaments of sarcomere help maintain enouth myofilament overlap to ensure effective contraction when muscle is called to action

extrafusal fibers

make up the rest of the muscle (not in the muscle spindle) they do the work.

Unmyelintated nerve fibers

many nerve fibers in both CNS and PNS are unmyeinated. but in the PNS even the unmyelinated cells are covered with Schwann cells. Schwann cell harbors from 1 to 12 small nerve fibers in groves in its surface. the Schwann cell's plasma membrane doesn't spiral repeatedly around the fiber like a myelin sheath, instead it folds once around each fiber and somewhat overlaps itself along the edges. this wrapping is the neurolemma. most nerve fibers travel through individual channels in the Schwann cell but small fibers are sometimes bundled together within a single channel. Basal lamina surrounds entire Schwann cell with its fibers.

decussation

many tracts undergo this, they pass up or down the brainstem and spinal cord, meaning they crossover from left side to the right. as a result, the left side of the brain recieves more sensory and the right recieves more motor

sliding filament theory

mechanism of contraction, it holds that the myofilaments do not become any shorter during contraction, they instead the thin filaments slide over the thick filaments and pull the z disks behind them, causing each sarcomere as a whole to shorten

spacial summation

occurs when EPSPs form several synapses add up to threshold at the axon hillock. any one synapse may admit only a moderate amount of Na+ into the cell, but several synapses acting together to admit enough Na+ to reach threshold. presynaptic neurons collaborate to induce the postsynaptic neuron to fire.

temporal summation

occurs when a single synapse generates EPSPs so quickly that each is generated before the previous one fades. this allows the EPSPs to add up over time to a threshold voltage that triggers an action potential. it can occur if even one presynaptic neuron stimulates the postsynaptic neuron at a fast enough rate.

lateral horn

on each side of gray matter, contains neurons of the sympathetic nervous system, send axons out of the cord by way of the anterior root along with somatic efferent fibers.

axon hillock and axon

on one side of the soma, its a mound from which the axon originates. axon is cylindrical and relatively unbranched for most of its life. most axons branch at distal ends. axon is speciallized for rapid conduction of nerve signals to points remote from the soma.

endurance (aerobic) exercise

one example of this is jogging and swimming. it improves fatigue resistance by enhancing the delivery and use of oxygen. slow twitch fibers especially produce more mitochondria and glycogen and acquire a larger density of blood capillaries because of conditioning. it also improves skeletal strength, increases blood cell count and oxygen transport capacity of the blood. and enhanced the function of the cardiovascular, respiratory, and nervous system. it does not increase muscle strength significantly and resistance training doesnt improve endurance significantly

diverging

one fiber branches and synapses with several postsynaptic cells. each of those may synapse with several more, so input with one neuron, may produce output through hundreds of neurons. this circuit allows one motor neuron from the brain to simulate thousands of muscle fibers.

elastic filaments

one nanometer in diameter, made of huge springy protein called TITIN. run through the core of thick filaments and anchor it to structures ( Z-disks) at one end (M-lines) at the other end. elastic keeps thick fibers from moving away from the center of the thin filaments, prevents over stretching, and recoils after a muscle is stretched

Alzheimers disease

one of the two most common dogenerative disorders of the brain (other is parkinson) both associated with neurotransmitter deficiencies. difficult to diagnose,first sign is memory loss of recent events, may ask same question frequently, may become moody, confused, paranoid, or combative may lose teh ablitity to walk, eat, write, ect, death ensues. leading cause of death among the elderly. diagnosis can be confirmed by autopsy atrophy of gyri folds, cerebral cortex, and hippocampus, an important center for memory. senile dementia- in this autopsy there are senile plaques consisting of aggregations of cells, altered nerve fibers, and core beta amyloid proteins. AD seems to be genetic, people with Down syndrome seem to get it more often, shoe deficiencies in ACh and nerve growth factor.

converging circuit

opposite of diverging, input many fibers funneled into one neuron or neural pool. this arrangement can be seen in your eyes, inner ears, and stretch receptors in your neck to be directed to the area of the brain concerned with balance. also the respiratory system in the brain stem recieves input from the parts of your brain from receptors from blood chemistry in your arteries and from stretch receptors in your lungs. resperatory center can produce output receptors that take all the factors into account and set a good breathing pattern.

visceral reflexes

organs such as heart and intestines . smooth muscle, cardiac muscle, and glands.

striations

overlapping arrangement of internal contractile proteins.

cramps

paiful muscle spasms caused by rapid firing of motor neurons; triggered by heavy exercise, extreme cold, hehydration, electrolyte loss, low blood glucose, or lack of blood flow.

white matter

white apearance, ABUNDANCE OF MYELIN, composed of an abundance of axons called TRACTS, that carry signals from one level of the CNS to another. both gray and white have an abundance of Glial cells. surrounds gray matter in spinal cord. consists of bundles of axons that course up and down the cord and proved avenues of comunication between different levels of CN. budles arranged in pairs called columns (posterior, anterior, and lateral) and subdivisions of columns called tracts

Fast Glycolytic fibers

white muscles chicken breast for short burst of energy during fighting. larger motor units made of larger FG fibers, supplied by larger less excitable neurons and produce more power but less fine control. multiple motor unit summation, in the nervous system recruits small SO motor units first then larger FG if more strength is needed. -some people are born with genetic predisposition for certain ratios of fiber types, this helps them to become more successful at certain athletics more than others (born sprinter). -fewer mitochondria and glycogen -lower capilary density -rich in enzymes such as phosphagen and lactic acid -SR release calcium quickly -quick twitches -fatigue quickly

how does sodium effect the RMP

without it cell would be about -90mV, sodium is about 12x more in the ECF than the ICF. resting plasma membrane is much less permeable to the Na+ than to the K+, but Na+ does not diffuse down its concentration gradient into the cell, attracted by the negative charge in the ICF. sodium leak is only a trickle but is enough to cancel some of the negative charge and reduce voltage across the membrane. SODIUM=IN (leaks into the cell) and POTASSIUM=OUT (leaks out of the cell).

What does muscular strength depend on?

~Muscle size, thick muscles can make more myosin-actin cross bridges so generates more tension. ex. weightlifting increases size and strength of muscles. ~fascicle arrangement- pennate muscles such as quadriceps are stronger than parallel muscles. ~size of active motor units- larger motor units make stronger contractions than smaller ones. ~multiple motor unit summation- when stronger muscle contract. is desired nervous system activates more and larger motor units. (ex. getting psyched up for physical competition) ~Temporal summation- nerve impulse usually arrive at a muscle in a series of closely spaced action potentials. the greater the frequency of summation, the more strongly a muscle contracts. ~ length-tension relationship- a muscle resting at optimum length is prepared to contract more forcefully than a muscle that is excessively contracted of stretched. ~Fatigue- rested muscles contract more strongly than fatigued ones.

repolarization

the loss of K+ ions from the cell turns the inside membrane negative again , creates a quick down volt shift

synaptic knob

the nerve fiber ends in this bulbous swelling, the knob doesnt directly touch the muscle fiber but is separated by a space called a synaptic cleft, the space is about the thickness of a plasma membrane. and a schwann cell envelops the entire junction and isolates it from the surrounding tissue fluid. synaptic knob contains synaptic vesicles, filled with acetalcholine (ACh)- a neurotransmitter, synaptic vesicles undergo exocytosis when ach is released into the cleft

presynaptic inhabitation

the opposite of facilitation, a mechanism in which one presynaptic neuron suppresses the other one. this mechanism is used to reduce or halt unwanted synaptic transmission. when there is a blocked pathway due to a presynaptic inhibitor, neuron inhibitor releases neurotransmitter GABBA, that prevents the voltage-gated calcium channels of stimulus neurons from opening. as a result stimulus neurons release less neurotransmitter or none, and fails to stimulate the responder neuron.

neural circuit

the pathways among its neurons. a wide variety of neural functions result from the operation of four principal kinds of neural circuits. -diverging -converging -reverberating -parallele after discharge

refractory period

the period of resistance to restimulation. during action potential, and a few milliseconds after, it is difficult or impossible to stimulate that region of a neuron to fire again. there are two phases, absolute refractory period and relative refractory period .

excitation

the process in which action potentials in nerve fiber lead to action potentials in the muscle fiber

summation

the process of adding up postsynaptic potentials and responding to their net effect. one neuron may receive input from from thousands of other neurons. some incoming nerve fibers may produce EPSPs while others produce IPSPs. the neuron's response depends on weather the NET input is is excitatory or inhibitory. if EPSPs override the IPSPs, threshold may be reached snd set off action potential, if they prevail they inhibit the neuron from firing. a single action potential in a synaptic knob does not produce enough activity to make a post synaptic cell fire. ans EPSP may be produced, but fades before reaching threshold. a typical ESPS is a voltage change of only .5mV and lasts only 15 to 20 ms. if a neuron has a RMP of -70 mV and a threshold of -55mV it needs at least 30 ESPS to reach the threshold and fire the two ways EPSPs can add up to this: temporal summation and spacial summation

synaptic potentiation

the process of making transmission easier. one form of synaptic plasticity. like learning to tie shoes

resting membrane potential effect factors

the reason the cell has a resting membrane potential is that the electrolytes are unequally distributed between the ECF and the ICF. the RMP results from the effect of these 3 factors 1. diffusion of ions down their concentration gradient through the membrane. 2. selective permeability of the membrane, allowing some ions to pass more easily than others. 3. electrical attraction of cations and anions to each other.

declarative memory

the retention of events and facts that you can put into words. numbers names, dates, ect.

fascia

the sheet of connective tissue that separates neighboring muscles or muscle groups. form subcutaneous tissue, this is what makes the muscle compartments

depolarization of a neuron

the sodium inflow cancels some of the internal negative charge, so the voltage across the plasma membrane drifts toward zero. any such case in which the voltage shifts to a less negative value

contraction

the step when the muscle fiber develops tension and may shorten (muscles often contract or develop tension without shortening)

electrophysiology

the study of electrical activity of cells. a key to understanding nervous activity, heart beat, muscle contraction, and other physiological phenomena

myology

the study of the muscular system

enzyme delay

the time from the arrival of a signal to the axon terminal of a presynaptic cell to the beginning of an action potential in postsynaptic cell.

axonal transport

the two-way passage of proteins, organelles, and other materials along an axon. all proteins needed by a neuron must be made in the soma. protein synthesizing organelles such as the muscles, ribosomes, and rough ER are located. many proteins are needed in the axon to repair and maintain the axolemma. movement away from the soma down the axon is called anterograde transport, and movement up the axon toward the soma is called retrograde transport. materials travel along axonal microtubules that act like monorail tracts to guide them to their destination. a motor protein called kinesin and retrograde transport uses one called dynein these proteins carry materials while they reach out like myosin heads of muscle to bind repeaditly to the microtubules and walk along them.

resting membrane potential (RMP)

the voltage within a muscle cell, typically about -90mV, negative sign means ICF's net charge is negative. it can be maintained by sodium-potassium pump

neuralgia or glial cells

there are more of these than nerve cells, they protect the neurons and help them function. roles to bind and provide a supportive framework for the nervous tissue.

tracts

there are two types Ascending and descending

why arent all nerve fiber large and myelinated and fast?

these fibers are very large and if we only had this type our nervous system would be impossibly bulky or limited to fewer fibers. large fibers require large somas and a large expenditure of energy to maintain them. nervous system has evolved to have some smaller more efficient nerve fibers, these are used for responses that do not require a quick reaction such as secreting stomach acid or dilating pupil. fast myelinated fibers are placed where speed is more important these are actions such as motor commands to skeletal muscle and sensory signals.

procedural vs declarative

these forms of memory are formed in different places in the brain, but similar at cellular level. some LTM involves the physical remodeling of synapses or the formation of new ones through the growth and branching of axon terminals and dendrites. a study on fish shows that when they are deprived of sensory their spines shrink, this is a clue to how important sensory is to infants and small children

somatic motor neurons somatic nerve fibers*

these nerve cells are what serve skeletal muscles, cell bodies are in the brain stem and spinal chord . their axons are called somatic motor fibers they lead to the muscles, and each nerve fiber branches to multiple muscle fibers. one muscle fiber only has one motor neuron

neuromodulators

they adjust or modulate the activity of a neuron groups in many ways such as: increasing release of neurotransmitter by presynaptic neurons, adjusting the sensitivity of post synaptic neurons to neurotransmitters or altering the rate of neurotransmitter reputake (breakdown) Neurons sometimes secrete chemical signals that last for long-term effects on an entire group of neurons instead of brief quick effects at an individual synapse. Nitric oxide (NO) diffuses readily into a postsynaptic cell and activates second messenger pathways with such effects as relaxing smooth muscle.

myosin and actin striations

they are not only found in muscle cells, also in any cell that uses mobility, mitosis, and transport of intercellular materials. but especially abundant in skeletal and cardiac muscle cells. they are organized in an array of striations for the diffetend types of muscles (A and I bands)

muscle fascicle

visible to the naked eye, parallel strands, when eating meat you can sometimes pull apart the fascicle

action potential characteristics?

- ALL or NONE law (if a stimulus depolarizes the neuron to threshold, the neuron to threshold, the neuron fires at its maximum voltage; if threshold is not reached, neuron does not fire at all. Not graded. - Nondecremental (do not get weaker with distance) -Irreversible (if neuron reaches threshold, action potential goes completion, cant be stopped once it begins like a trigger on a gun)

In high intensity, short duration exercise, fatigue is thought to result from what?

- Potassium accumulation, each action potential releases K+ from the sarcoplasm to the extracellular fluid, lowering membrane potential and makes muscle fiber less excitable, most significant in T-tubules where low volumes of ECF enables the K+ concentration to a high level and interfere with release of calcium from the sarcoplasmic reticulum - ADP/P accumulation, hydrolysis of ATP generates an ever-growing pool of ADP +P. ADP slow the cross bridge cycle mechanism of contraction. the free phosphate inhibits calcium release from SR. calcium sensitivity of contractile mechanisms and force production by the myofibrils. it is now thought to be a major contributor to fatigue Lactic acid accumulation, a long known thought that lactic acid that is made my anaerobic fermintation contributes to fatigue by lowering the Ph in the muscle fiber. Alterations in protein conformation by low ph can interfere . lactic acid is removed to the liver about as fast

how does myelin speed up conduction?

- by wrapping tightly around axon it seals the nerve fiber and creates resistance to leakage of Na+ out of the axon so sodium ions maintain a higher density on the inner face of the membrane and transfer energy from one to another more easily. - myelin creates a better seperation from ICF ans ECF. cations and anions are therefor less attracted to each other, so sodium ions can now travel freely within the axon transferring energy from one to another.

excitation od smooth muscle

-Autonomic nerve fibers and neurotransmitters -chemicals -temperature -stretch -autorythmicity

conduction speed depends on what?

-Fiber diameter (surface area) -myelinated (faster)/ Unmyelnated (slower) small myelinated fibers: .5m/s small unmyelinated: 3-15m/s large myelinated: up to 120m/s

low intensity, long duration exercise, fatigue may result from what?

-Fuel depletion- declining levels of muscle glycogen and blood glucose leaves less fuel atp synthesis "hitting the wall" -Electrolyte loss- loss of electrolytes through sweating can alter the ion balance of the extracellular fluid enough to reduce muscle excitability. -central fatigue- exercising muscles generates ammonia, which is absorbed by the brain and inhabits motor neurons of the cerebrum. for this and other reasons not yet well understood, the central nervous system produces less signal output to the skeletal muscles. this is where psychological factors come into play, ex. the will to complete a marathon

what are the two major anatomical subdivisions

-central nervous system -peripheral nervous system

local potential

-produced by gated channels on the dendrites and soma. -may be a positive (depolarizing) or negative (hyperpolarizing) voltage change. -graded; proportional to stimulus strength -reversible; returns to RMP if stimulus ceases before threshold is reached -local; has effects for only a short distance from point of origin -decremental; single grows weaker with distance ligand binds to receptor, receptor is ligated-regulated Na+ gate, opening of gate allows Na+ inflow, inflow depolarizes membrane.

what are the functions of the spinal cord?

1. Conduction- contains bundles of nerve fibers that conduct info up and down the cord. enables sensory info to reach the brain, motor commands to reach the effectors, and input received at one level of the cord to affect output from another level. 2. Neural integration- pools of spinal neurons receive input from multiple sources, integrate the info, and execute an appropriate output. (ex. spinal cord can intergrate and stretch sensation from a full bladder with cerebral input with appropriate place to urinate) 3. Locomotion- walking involves repetitive, coordinated contractions of several muscle groups in the limbs, motor neurons in the brain initiate walking and determine its speed, distance, and direction ( group of neurons called central pattern generators, used in repetetive movement of walking) 4. reflexes - spinal reflexes play vital role in posture, motor cordination, and protective responses. (pain or injury)

cessation of the synaptic transmission (signal)

1. Diffusion -neurotransmitter escapes from the synapse into the nearby ECF, the CNS astrocytes absorb it and return it to the neurons 2. Reuptake- synaptic knob reabsorbs amino acids and monoamines by endocytosis and breaks them down with the enzyme monoamine oxidase (MAO) 3. Degradation in the synaptic cleft- enzyme ACh, located in the synaptic cleft and on postsynaptic membrane, breaks ACh down into acetate and choline. breakdown products have no stimulation effect on postsynaptic cell. synaptic knob reabsorbs the choline and uses it to make more ACh.

What are the four major steps of muscle contraction?

1. Excitation 2. excitation-contraction coupling 3. contraction 4. relaxation

what are the three main categories of neurotransmitters?

1. acetylecholine- in a class by itself, formed from acetic acid (acetate) and choline 2. amino acid- glycine, glutamine, aspartate, and GABA 3. monoamines- synthesized by amino acids by removal of the -COOH group. some are: epinephrine, norepinephrine, dopamine, histamine, ATP, and serotonin. the first three are subclasses as catecholamines. 4. neuropeptides- chains of amino acids, cholecystokinin, substance P, enkephalins, B-endorphine. stored in secretory granules some also function as hormones or neuromodulators, some are produced in the digestive tract and by neurons. gut-brain peptides

what are the steps in transmission at a cholinergic synapse?

1. arrival of a nerve signal at synaptic knob opens voltage-gated calcium channels 2. Ca+2 enters the knob and triggers exocytosis of the synaptic vesicles, releasing ACh 3. empty vesicles drop back into the cytoplasm to be refilled with ACh, while synaptic vesicles in the reserve pool move to active sites and release ACh 4. ACh diffuses across the synaptic cleft and binds to ligand gated channels on the postsyaptic neuron. channels open Na+ channels and K+ leaves through the same gate. 5. Na+ enters and spreads along the inside of the plasma membrane and depolarizes it, producing local voltage shifts called pst synaptic potential. if this is strong and persistent enough, it opens voltage-gated ion channels in the trigger zone and causes the postsynaptic neuron to fire.

what are the steps of step one excitation

1. nerve signal arrives at synaptic knob and opens voltage-gated calcium channels. calcium enters the synaptic knob. 2. calcium stimulates the synaptic vessicals to release ACh into S.cleft, one action potential causes exocytosis of vessicals, and vessicals release ACh 3. Ach diffuses across the synaptic cleft and binds to receptors on sarcolemma 4. reseptors= ligand-gated channels. two ACh molecules bind to receptor to open the channel. When it opens Na+ flows quickly inot the cell and K+ flows out , as a result sarcolemma reverses polarity, its voltage quickly jumps from RMP of -90 mV to a peak of +75 mV as Na+, then falls bacl to a level close to RMP as K+ exits 5. areas of sarcolemma next to the ends plate have voltage gatted ion channels that open in response to the EPP. some are specific to sodium (admit it into cell)and others are specific to potassium (allow out of cell), this is what creates an action potential. (muscle fiber is now excited!)

what are the types of neuroglia

1. oligodendrocytes 2. ependymal 3. microglia 4. astrocytes 5.Schwann 6. satellite

what are the important properties of a reflex?

1. require stimulation (they are responses to sensory input) 2. quick (generally involve few interneurons, or none and minimum synaptic delay.) 3. involuntary (occur without intent) 4. stereotyped ( occur in essentially the same way every time)

what are the steps the nervous system carries out its coordinating tasks?

1. sene organs and simple nerve endings, it receives info. about changes in the body and external enviroment and transmits messages to the cns. 2. cns processes this info and determines what response, if any is appropriate to the circle and glad cell ti carry out such responses 3. CNS issues commands primarily to muscle and gland cell to carry out such responses.

what are the functional classes?

1. sensory (afferent) neurons 2. interneurons (association neurons) 3. Motor (efferent) neurons

what are the ways in which an adrenergic synapse can function?

1. unstimulated NE receptor is bound to a G protein. 2. binging of NE to the receptor causes the G protein to dissociate from it 3. G protein binds to adenylate cyclase and activates this enzyme, which converts ATP to cAMP. 4. cyclic AMP can induce several alternative effects in the cell. 5. one effect is to produce an internal chemical that binds to a ligand-gated ion channel from the inside, opening the channel and depolarizing the cell. 6. another is to activate preexisting cytoplasmic enzymes, which can lead to diverse metabolic changes (ex. lever cell breakdown glycogen and release glucose into blood) 7. and another is when cAMP to induce genetic transcription, so that the cell produces new enzymes leading to diverse metabolic effects.

what are the steps to regenerate a nerve fiber?

1. when fiber is cut, the fiber distal to the injury cant survive because cant do protein synthesis. protein synthesizing organelles are mostly in soma, as distal fiber degenerates so does schwann cells. Macrophages clean up. 2. Soma presents abnormalities, soma swells, ER breaks up, (nissl bodies disperse), nucleus moves off center, some neurons die at this stage but often axon stump sprouts multiple growth processes as the severed distal ends show continued degeneration of its axon and schwann cells. denervation atrophy nerve shrinkage 3. schawnn cells, basal lamina, and neurolemma, form a regeneration tube. schwann cell prodcue cell-adhesion molecules and nerve growth factors that enable a neuron to regrow to its original destination, when growth process finds its way into tube, grows rapidly and other growth processes are retracted 4. regeneration tubes guide growing sprouts back to original target cells, reestablishing synaptic contact. 5. when contact is established, soma shrinks and returns to its original appearance, and reinnervated muscle fibers grow.

what are the steps of an action potential?

1. when local current arrives at the axon hillock, it depolarizes the membrane at that point, steady rising of action potentials 2. local potential must rise to critical voltage called threshold. (-55mV)-the minimum needed to open the gated channels 3. neuron now fires or produces an action potential at threshold, voltage Na+ channels open quickly while K+ channels open more slowly. initial effects on the membrane potential is therefor due to Na+. Na+ further depolarizes the membrane. creates a positive feedback loop of Na+ gated depolarization 4. rising potential passes, Na channels are inactivated and begin closing. by the time they all close, na flow stops. voltage peaks at +35. membrane is now positive on the inside and negative on outside. (polarity reversed) 5. slow K+ channels are fully open, K are repelled by positive charge and leave the cell. this repolarizes the membrane 6. K channels stay open longer than Na channels, so slightly more K leave the cell than Na that enter the cell. the membrane drops down to negative (hyperpolarization) 7. Na and K switch places across the membrane during an action potential, hyperpolarization, Na diffusion into cell and removal of extracellular K by astrocytes gradually restore the original RMP.

what are the steps for step 3: muscle contraction?

10. myosin head must have ATP molecules bound to it to begin the contraction. Myosin ATPase (enzyme in head) hydrolyzes the ATP into ADP and P. this energy released activates myosin head (moves to a cocked high energy position) head is temporaraly bound to the ADP and P 11. cocked myosin binds to an exposed active site on the tin filament, forming a cross bridge between myosin and actin 12. myosin releases the ADP and P and flexes into a bent low energy position, tugging thin fil. with it, this is called power stroke. head remains with actin until it binds to a new ATP 13. binding of ATP to myosin destabilizes the myosin actin bond, breaking the cross-bridge. myosin is now prepared to repeat whole process (10-12) with a recovery stroke to attach to a new filament and produce another power stroke.

what is the size of a muscle cell

100 nanometers in diameter a d 3 cm long. some are as thick as 500 nanometers

what are the steps for step 4: muscle relaxation?

14. nerve signals stop arriving at the neuromuscular junction, so the synaptic knob stops releasing ACh 15. as ACh dissociates (seperates) from it receptor, AChE breaks it down into fragments that cant stimulate the muscle, synaptic knob reabsorbs these fragments for recycling (this happens when muscle is stimulated as well), when nerve signals stop, no more ACh is released to replace that which breaks down , stimulation from ACh ceases. 16. from excitation through contraction, the SR simultaneously releases and reabsorbs calcium, but when the nerve fiber stops firing and excitation ceases so does the release of calcium, only reabsorption continues. Ca+2 binds to the protein calsequestrin, allows SR to store calcium 17. owing and reabsorption by the SR, the level of free calcium in the cytosol falls dramatically. now when calcium dissociates from troponin it isnt replaced 18. tropomysin moves back into position where it blocks the active sites of the actin filaments. myosin can no longer bind to actin and muscle fiber ceases to produce or maintain tension.

thick filaments

15 nanometers in diameter, made of several hundred molecules of protein called myosin ( have heads and tales

what are the steps for step two excitation-contraction coupling?

6. wave of action potentials spread from motor end plate in all directios, when wave reaches T-Tubules, continues down into the cell interior. 7. action potentials open voltage-gated ion channels in T-tubules, they are linked to calcium channels in the terminal cisternae of sarcoplasmic reticulum. channels in SR are open also and calcium diffuses out down concentration gradient to cytosol. 8. calcium binds to troponin of tjin filiments 9. troponin-tropomyosin complex changes shape and exposes active sites on actin filiments, makes them available for binding to myosin heads.

thin filament

7 nanometers in diameter composed of mostly two intertwined strands of protein: Fibrous (F) actin and Globular(G) actin. Each F actin is like a beaded necklace, and the string of subunits is the G actin, each G actin has an active site that can bind to the head of the myosin molecule. thin filaments also contain proteins called tropomyosin

A bands and I bands

A= dArk I= lIght A band consists of thick filiments lying side by side. part of the A band where thick and thin filiments overlap is especially dark and the center is light ( H band), in the middle of the H band thick filaments are linked to eachother through protien coplex, M-line Light I bands are bisected by dark narrow Z disks which provides anchoring.

phospagen system

ATP and CP together, provide nearly all the energy used for short bursts of intense activity. amount of CP (ceratine-phosphate) can drop drastically but amount of ATP fibers dont change much. important in activities that are breif but maximal such as football, baseball, and weight lifting.

myocytes

Any muscle cell can be called this, it is a term preferable to muscle fibers for the smooth and cardiac tissues. because these two do nt hace long fibrous shape of skeletal tissue. they are relatively short and further contrast to skeletal fibers by only having one nucleus. cardiac myocytes can be called cardiocytes. cardiac and smooth are inviluntary, receive no innervation from somatic motor neurons, but they both receive nerves from sympathetic and parasympathetic divisions of autonomic nervous system.

What are the two organ systems dedicated to maintain internal coordination?

Endocrine system (communicates by means of chemical messengers or hormones, secreted into the blood) and Nervous system (which employs electrical and chenical means to send messages very quickly from cell to cell.

recruitment

QUANTITATIVE info. about the intensity of a stimulus- encoded in two different ways, one depends on the fact that different neurons have different thresholds of excitation. (weak stimulus, excites neurons at lowest threshold). bringing additional neurons into playas the stimulus becomes stronger. enables nervous system to judge stimulus strength by which neurons and how many of them, are firing.

long- term potentiation

LTM can be grounded by these molecular changes, NMDA receptors that are glutamate-binding receptors found in dendrite spines of pyrimidal brain cells they usually block magnesium ions but when they bind glutamate and are subjected to tetanic stimulation, they expel the Mg and open to amit Ca into dendrites.

what are the functions of muscles?

Movement- enable us to move and place individual body parts, and body contents such as breathing, feeding and digestion. and various roles in speech. Stability- muscles maintain posture by preventing unwanted movements. some are called anti-gravity muscles. Control of body openings and passages- ex. muscles encircle for food intake and chewing. Heat Production- skeletal muscles produced as much as 85% of the body heat, vital to functioning enzymes and therefor to all metabolism Glycemic control- means regulation of blood glucose concentration within its normal range.

smooth muscle

NO striations (meaning no sarcomeres) myocytes are relatively small allowing for fine control of tissues and organs such as a single hair, iris, and tiniest arteries, in pregnant uterus myocytes become quite large and produce powerful contractions of childbirth. when smooth is inverted nerve supply is autonomic, like the heart. Autonomic nerve fibers do not form precisely localized neuromuscular junctions with myocytes, insted a nerve fiber has as many as 20,000 periodic swellings called Varicosities along its length, each varicosity contains a synaptic vesicle from which it releases neurotransmitters. usually norephrine from sympathetic fibers and acetocholine from parasynthetic fibers.

cardiac muscle

ONLY THE HEART. functions to pump the blood. properties cardiac muscles must have 1. must cantract with regular rhythm 2. must function in sleep and wakefulness 3. must be highly resistant to fatigue 4. cardiocytes of given heart chamber can effectivly expel blood 5. contraction must last long enough to expel blood from the chamber

origin and insertion

Origin- bony site of attachment at relatively STATIONARY end. Insertion- attachment site at its more MOBILE end. middle of muscle is called the belly

relaxation phase

SR quickly reabsorbs Ca+2 before the muscle develops maximal force. as ca in cytoplasm reduces myosin release the thin filaments and muscle tension declines. (seen on myogram). lasts longer than the twitch.

maximum oxygen uptake

The ability to maintain high-intensity exercise for more maximum oxygen uptake the point at which the rate of oxygen consumption reaches a plateau and does not increase further with an added workload VO2 max is proportional to body size and it peaks at age 20. Its usually greater in males than in females. can be twice as great in a trained endurance athlete. normal secondary adult uses about 25 mm of oxygen per minute per kilogram of body weight. this is what can calculate how many calories are burned

facilitation

a process in which one neuron enhances the effect of another. in spacial summation for example one neuron acting alone may be unable to induce a post synaptic neuron to fire. but when they collaborate, their combined effort does induce a postsynaptic cell.

twitch

a quick cycle of contraction and relaxation. it can only occur if the threshold is met.

define local potential

a short rang change. incoming sodium diffuses for short distances along the inside of the plasma membrane and produces a current that travels from one point of stimulation toward the cells trigger zone.

anaerobic fermintation

enables cells to produce ATP without oxygen, but the yield is very limited and process generates lactic acid which contributes to muscle fatigue,

long term energy system

after 40 seconds resperatry and cardio catch up and deliver oxygen to the muscles fast enouh for aerobic respiration to meet most of ATP demand. this produces much more ATP that glycolysis. after a while levels drop off to a steady state, after 30 minutes fatty acid becomes more sufficient energy source.

what are the ATP sources

all muscle contractions depend on ATP, ATP depends on glucose and fatty acid to make ATP. ATP synthesizes aerobic and anaerobic respiration and fermentation.

concentric contraction

a muscle SHORTENS as it maintains tension ex. biceps contracts and flexes the elbow. or lifting dumbbell

what is a ganglion

a cluster of neurosomas outside of the CNS. resembles a knot on a thread, if the thread was a nerve. enveloped in an epineurium continuous of that of a nerve. among the neurosomas there are bundles of nerve fibers leading into and out of the ganglion.

crossed-extension reflex

a contraction of the extensor muscles in the limb opposite from the one that is withdrawn. maintinance of balance, like the situation with the glass in the lake, you lift the hurt leg up, and the other leg straitens to keep from falling. the straitened leg is a cross-extension reflex. ipsilateral reflex arc- flexor reflex, sensory input and motor output are on the same side of the spinal cord. contralateral reflex arc- crossed extension reflex, input and output are on opposite sides. inter segmental reflex arc- one in which input and output occur at different levels (Segments) of the spinal cord (ex. pain in foot causes contractions in abdomin or hip muscles higher in body)

spinal cord

a cylinder of nervous tissue that arises from the brain stem at the foramen magnum of the skull. passes through vertebral canal as far as the inferior margin of the first lumbar vertebra (L1-L2) or slightly beyond. 45cm long, and 1.8 cm thick in adults (as thick as a pinky). cervical enlargement- gives rise to the upper limbs nerves lumbar enlargement- gives rise to the nerves of the pelvic region and lower limbs

latent period

a delay, about 2 milliseconds between the onset of the stimulus and onset twitch. its the time required for excitation, excitation contraction, and tension of elastic components of muscle. force made at this time is called internal tension (cant see on myogram because there is no shortening of muscle). once elastic components are taunt the muscle begins to develop external tension and move a load (such as a body limb).

electrical potential

a difference in the concentration of charged particles between one point and another. a form of potential energy that, under the right circumstances can produce a current. an electrical current is a flow of charged particles from one point to another. as long as the object has a potential (voltage) it is polarized.

satellite cells

a form of myoblasts that remains unspecialized. located between muscle fibers and endomysium. Important role in regeneration of demand skeletal muscle.

Node of ranvier helps the Myelinated Internodes in an action potential how?

a signal cant travel long before it becomes too weak to open voltage-gated sodium channels, fortunately there is a node of ranvier every millimeter along the axon and it is exposed to extra cellular fluid and has an abundance o voltage gated channels. each node of ranvier boosts the signal back to its strength (+35mV), but this is very time consuming and slows down nerve signal at the nodes. since action potentials occur only at nodes, looks like action potential are jumping from node to node- conduction in myelinated fibers is therefor called saltatory conduction.

nerve signal

a traveling wave of excitation produced by self-propagating action potentials. like a line of falling dominos. action potential cant travel back to the soma because the membrane behind the nerve signal is still in its refractory period, only the membrane ahead is sensitive to stimulation. refractory period ensures that nerve signals are conducted in the proper direction, from the soma to the synaptic knobs.

working memory

a type of short term memory, allows us to hold info in our mind long enough to carry out an action such as calling a phone number or looking for keys while remembering where you have already looked. uses facilitated circuits.

nerve impulse (nerve signal)

a wave of action potential t one point on a plasma membrane causes another one to happen right in front of it. spreads across a nerve fiber

Fast twitch fibers

also called fast glycolytic. or type two fibers. well adapted for quick responses so they are particularly important in the adapted eye and hand muscles. in big muscles the quickness comes from an especially extensive sarcoplasmic reticulum with fast release and reabsorption of calcium and a form of myosin with very quick ATP hydrolisis and cross bridge cycling. energy dependent on anaerobic they contain high levels of glycogen and phosphate and fewer mitochondria than slow-twitch because fibers are thicker than slow twitches. causes fatigue faster. ex. writing cramp

direct attachment

also called fleshy attachment. theres so little separation between bone and muscle, it looks like the muscle comes directly out of the bone. Ex. brachialis and lateral head of triceps brachii , microscopic level muscle and bone are seperated by collagen fibers.

Aspartate

amino acid, spinal cord, effects similar to glutamate LEARNING AND MEMORY

GABA

amino acid, thalamus, hypothalamus, cerebellum, occipital lobes, and retinas, most common INHIBITOR neurotransmitter in brain

Glutamate

an amino acid, cerebral cortex and brainstem. accounts for about 75% of all excitatory synaptic transmission in the brain; involved in LEARNING AND MEMORY

myosin ATPase

an enzyme in the myosin head, it hydrolyzes the ATP into ADP and P (creating energy)

parallel after discharge

an input neuron diverges ti stimulate several chains of neurons, each chain has a different number of synapses, but eventually they all re-converge on one or few output neurons. since the chains differ in synaptic delay, the signals arrive at the output neurons at different times and the output neurons may go on firing for some time after input has ceased (called after-discharge). unlike reverberating circuit this type has no feedback loop. once all the neurons in the circuit have fired output is ceased. this is why you can stare at a lamp and then close you eyes and still see the image for a few seconds. this circuit is important for withdrawal reflexes- in which a brief pain produces a longer lasting output to the limb muscle and cause you to draw back the body part in danger.

slow axonal transport

anterograde process that works in a stop-and-go fashion. If we compare fast axonal transport to an express train traveling nonstop to its destination, slow axonal transport is like the local train that stops at every station. when moving it travels as fast as fast axonal but due to the "frequent stops" it is over all slower. moves enzymes and cytoskeleton components down the axon, renew worn-out axoplasmic compartments in mature neurons and supplies new axoplasm damaged neurons recover at slow axon transport speed.

nerve fibers of the peripheral nervous system?

are enshealted by schwann cells, which form a neurolemma and myelin sheath, round the axon. surounded my the basal lamina there is a thin sheath of connective tissue called the endoneurium, in most nerves, fibers form bundles called fasicles. each wrapped in a sheath called a perineurium, then several fasicles are bundled together and wrapped in a layer called an epineurium to compose the nerve as a whole (protects the nerve from stretching and injury). nerves have high metabolic rates and need plentiful blood supply, which is furnished by blood vessels and penetrate connective tissue coverings.

sympathetic

arouse the body for action. fight or flight reflexes. accelerating heart beat for example.

synaptic knob of a neuron

at distal end, axon has a terminal arborization (an extensive complex of fine branches), the end of these have synaptic knobs a little swelling that forms a junction (synapse) with the next cell. it contains synaptic vesicles full of neurotransmitters. autonomic neurons the axon has numerous beads called varicosities (carries synaptic vesicles and secrets neurotransmitters).

posterior root

attached to the spinal cord, carries sensory nerve fibers which enter the posterior horn of the cord and sometimes the synapse with an interneuron there. especially numerous in the cervical and lumbar enlargements .

contraction and relaxation of smooth muscles

calcium ions are immediate triggers for contraction but unlike skeletal and cardiac, smooth muscle has no troponin to bind. instead it binds to the protein calmodulin. calmodulin then activates enzyme myosin light-chain kinase. adds phosphate group to a small regulatory protein on myosin head this activates the myosin ATPase, enabling it to bind to actin and hydrolyze ATP. myosin produces repetitive power and recovery strokes like those of skeletal muscle. centers of cells shorten. latent period is much longer. has latched-bridge mechanism that enables it to remain attached to actin for a prolonged time without consuming more ATP, smooth muscle often exhibits tetanus and resistant to fatigue has few mitochindria, requieres less atp. smooth muscle tone loss of tone in arteries in a state of partial constriction called vasomotor tone.

synaptic facilitation

can be induced by tetanic stimulation, the rapid arrival of repetitive signals at a synapse. each signal causes a certain amount of Ca+ to enter the synaptic knob. if signals arrive rapidly, the neuron cant pump all the Ca admitted by one action potential before the next action potential occurs. more Ca accumulates in the knob. since Ca is what triggers the release of neurotransmitter each new signal releases more neurotransmitter than the one before. with more neurotransmitter, the cell gets stronger and more likely to fire.

motor (efferent) division

carries out signals from the central nervous system to the glands and muscle. cells that carry out the bodies responses to these signals called effectors.

nerve cells (neurons)

carries out the communicative role of the nervous system. three fundamental properties that allow communication with other cells excitability (all cells respond to stimuli), conductivity (electrical signals that are quickly conducted to other cells at distant locations), and secretion (when signal reaches end of a nerve fiber neuron secretes a neurotransmitter that crosses the gap and stimulates the next cell).

somatic sensory division

carries signals from receptors in the skin, muscles, bones, and joints.

visceral sensory division

carries signals from the viscera to of the thoracic and abdominal cavities such as heart, lungs, stomach, and urinary bladder.

sensory (afferent) of the PNS

carries signals from various receptors to the central nervous system. this pathway informs the central nervous system of stimuli within and around the body. it divides into somatic and visceral.

visceral motor division (autonomic nervous system)

carries signals to glands, cardiac muscle, and smooth muscle. usually they have no voluntary control over these effectors, and the ANS operates at an unconscious level. the responses of the ans and its effectors are visceral reflexes. ANS divides further into parasympathetic and sympathetic

somatic motor division

carries signals to the skeletal muscles. produces VOLUNTARY muscle contractions as well as involuntary somatic reflexes.

cholecystokinin

cerebral cortex and small intestine, SUPPRESS APPETITE

saltatory conduction

conduction in myelinated fibers. in myelinated fibers, action potentials occur only at the nodes, it appears that the nerve signal jumps from from node to node. process is very fast in the internodes (transfer of energy from ion to ion). but decremental. in the nodes conduction is slower but non-decremental Myelinated fibers transfer action potentials faster than UNmyelinated .

spina bifida

congenital defect one or more vertebra fail to form a complete vertebral arch for enclosure of the spinal cord. common in lumbar/sacral region. spina bifida cystica is most serious form, sac protrudes from spine and may contain meninges, cerebrospinal fluid, and parts of spinal cord and nerve roots. women who take folic acid during pregnancy prevents spina bifida from happening.

peripheral nervous system

consists of all the rest, nerves and ganglia.

central nervous system

consists of brain and spinal cord, enclosed and protected by brain and vertebral column

Arachnoid mater

consists of simple epithelium, it adhears to the dura mater, and a loose mech of collagenous and elastic fibers spanning the gap between the arachnoid and the pia mater. this gap is called the subarachnoid space, and is filled with cerebrospinal fluid.

neural pool

consists of thousands to mullions of interneurons concerned with a particular body function. one control rhythm and breathing, others control your limbs rhythmically as you walk, one regulates sense of hunger. info arrives at the nerve pool through one or more input neurons which branch repeatedly and synapse with numerous interneurons in the pool . some input neurons form multiple synapses with a single postsynapse neuron. they can produce Excitatory post synaptic potential at all points of contact with that cell and through spacial summation

anterior horns

contain large somas of the somatic motor neurons. axons from these neurons exit by way of the anterior horn and lead to skeletal muscles.

ICF

contains a greater concentration of negative anions than the ECF especially negative charged proteins, nucleic acids, and phosphates they are trapped IN the cell and give its interior a net negative charge meaning that the cell is polarized, a ton of potassium ions are also in the ICF (K+)

ECF

contains more positive cations, contains a lot of sodium (Na+)

sodium-potassium pump

continually compensates for the leakage of potassium out and sodium in. it pumps three sodium out of the cell for every two potassium it brings in. consuming 1 atp for every exchange cycle. by removing more cations from the cell than it brings in contributes to about -3mv to the RMP. RMP =-70mV. sodium potassium pump contributes about 70% if energy (ATP) requirement of the nervous system. every signal generated by a neuron slightly upsets the distribution of the sodium and potassium, so the pump must work continually to maintain equilibrium.

nerve

cord-like organ composed of numerous nerve fibers (axons), bound together by connective tissue. a nerve can cary anywhere from a few nerve fibers to a million. nerves usually have a white color and resemble frayed string as tehy divide into smaller and smaller branches.

pia mater

delicate transparent membrane that closely follows the contours of the spinal cord. continues beyond medullary cone, as a fibrous strand (teminal filum) within lumbar cistern. eventually fuses with the dura mater to form coccygeal ligament that anchors the meninges

what does the cytoskeleton contain in a neuron?

dense mesh of microtubules and neurofibrils (boundless of actin filaments) that compartmentalize the rough ER into the dark-staining regions called nissl bodies. NO centrioles because no further mitosis is done after adolescence, neuron cells can live to be older than 100 years old. there are some unspecialized stem cells in the cns that do divide and develop into new neurons.

electrical potential (voltage)

differance in electrical charge from one point to another, on the sarcolemma of a muscle cell the voltage is typically typically about -90mV, this is small amount but vital for living. the negative refers to the charge of the cell on the intercellular side

what are the two types of muscle attachment

direct and indirect

What in the body is made of smooth muscle?

doent make organs themselves, but makes up certain layers in the walls of larger organs, such as stomach and urinary balader. in these cases the layer can consist of as small as one cell in small arteries. intestines and esophegous have thicker layer of longitudinal smooth msucle adjacent to a deeper thick inner layer of circular muscle. when longitudinal layer contracts it dilates and shortens, the the organ. ex. is bladder and stomach

Myofilaments

each myofibril has a bundle of parallel protein microfiliments called myofiliments.

Sarcomere

each segment of a myofibril from one Z disk to the next, the functional contractile unit of the muscle fiber. A muscle shortens because its individual sarcomeres shorten and pull z-disks closer to each other and they pull on the sarcolemma to achieve overall shortening of the cell

neurotransmitter discoveries

early 20th century, biologist assumed synaptic communication was electrical. cahal discovered the synaptic cleft. Otto Loewi demonstrated neurons communication by releasing chemicals, the Vagus nerve supply the haeart, among other organs and slow it down, he opened two frogs ad flooded the hearts wit saline he stimulated the vagus nerve of one frog, and its heart rate dropped as expected, he then removed the saline from the heart and squirted it directly to the heart of the second frog, solution alone reduced the frogs heart rate, contained something from the vagus nerve of the first frog. the substance was acetylcholine

the POWER of sodium

electric eel, can produce a shock of 500v at 1 amp. with only sodium currents in cells of it electrical organ, this shock can kill a person

electrical synapses and chemical synapse

electrical synapse- some neurons, neroglia, and cardiac and single unit smooth muscle do have this synapse. where adjacent cells are joined by gap junctions and ions diffuse directly from one cell to the next. have a advantage of quick transmission there is no delay for release and binding of neurotransmitter chemical synapse- integrate info. and make decisions, neurons communicate by neurotransmitters.

excitatory cholinergic synapse

employs ACh as its neurotransmitter. ACH excites some postsynaptic cells (such as skeletal muscles). and inhibits others but this discussion will describe an excitatory action.

Excitatory adrenergic synapse

employs the neurotransmitter norepinephrine (NE), monoamines and neuropeptides act through Second-messenger systems like cAMP. the receptor isnt an ion gated channel but a transmembrane protein associated with G-protein

white fibers

fast twitches are called this. without the need of such rapid oxygen uptake, they have less myoglobin. thick fibers are stronger and they have no need for especially rapid oxygen delivery to the deepest cytoplasm.

iila fiber

fast-twitch but oxidative and fatigue resistant. they are uncommon in humans. more common in other mammal species.

epimysium

fibrous sheath that surrounds the entire muscle. its outer surface, epimysium grades into the fascia. inner surface issues projections between fascicles, forms perimysium

dura mater

forms loose fitting sleeve called dural sheath around spinal cord and brain. it is a tough collagenous membrane about as thick as a rubber glove. space between bone and sheath is called epidural space, occupied by adipose, blood vessels, and loose connective tissue.

Rene Descartaes

french philosopher, still arguing Galen's philosophy in 17th century

neuron cell inclusions

glycogen granules, lipid droplets, melanin, and gold brown pigment (lipofuscin). lipofuscin is produced when lysosomes degrade worn out organelles and other products. accumulates with age, and pushes the nucleus to one side of the cell. lipofuscin granules are called wear-and-tear granules, most abundant in old neurons.

muscle compartment

group of functionally related muscles enclosed and separated from others by connective tissue fascia. Also contains nerves and blood vessels that supply muscle group. some of the fascia that separate one compartment are particularly thick and are called intermuscular septa

enkepalins

hypothalamus, limbic system, pituitary, pain pathways of spinal cord, and nerve endings of digestive tract. act as analgesics (pain relievers) by INHIBITING SUBSTANCE P, inhibit intestinal motility, secretion increases sharply in women in labor.

signal conduction in nerve fibers Unmyelinated

if a neuron is to communicate with another cell, a signal has to travel to the end of the axon. unmyelinated present a relatively simple cases of signal conduction, has voltage gated channels along its entire length. when action potential occurs at the trigger zone, Na+ enters the axon and diffueses for a short distance just beneath the plasma membrane. the resulting depolarization excites voltage-gated channels immediately distal to the action potential. sodium and potassium channels open and close just as they did at the trigger zone, and new action potential is produced. this chain reaction continues until the traveling signal reaches the end of the axon. Action potential itself doesnt travel along the axon, instead it stimulated the production of new action potentials just ahead of it. so we can distinguish action potential from nerve signal.

discharge zone

in an input neuron, the neruon acting alone can make the post synaptic cells fire.

aponeurosis

in some cases the tendon is this broad sheath, located in skull muscles, abdominal muscles, lumbar, hand, and foot. some cases groups of tendons from separate muscles pass under a band of connective tissue called retinaculum

neurolemma

in the schwann cell (myelin sheath), the thick outermost coil. the bulging body of the schwann cell contains all of its nucleus and most of its cytoplasm. outside of the neurolemma is a basal lamina and a thin sleeve of fibrous connective tissue called endoneurium.

multiple motor unit summation (MMU)

intensity vs. frequency contraction strength. sub threshold stimulus voltages make no twitch, threshold makes a weak twitch, and rasing the voltage we will see stronger twitches. because higher voltages excite more and more nerve fibers in the motor nerve and stimulate more motor units to contract. this process of bringing more motor units into play is called MMU summation. these twitches increase to a maximum where all the motor units are active. important in voluntary control of muscle strength.

electromechanical gradient

ion channels in the plasma membrane open and Na+ instantly flow into the cell, driven by its concentration difference across its membrane and by its attraction to the negative charge of the cell interior, when sodium channels close again potassium flows out to the ECF classifying it as flowing down its own electromechanical gradient

collagen

its neither excitable nor contractile, but can be extensible and elastic. When a muscle lengthens, for example during an extension of a joint, the cortilagenis component resists excessive stretching and helps the muscle recoil and relaxin. keeps the muscle from becoming too flaccid

what is a cardiac muscle made of?

its striated like skeletal muscles, but they are shorter and thicker. Each is joined at the end with several others through linkages called intercalated discs. the disks look like dark lines in stained tissue sections, they have electrical gap junctions that allow each cardiocyte to directly stimulate its neighboring and mechanical junctions that keep the cardiocytes from pulling apart when heart contracts. t-tubules are larger and admit ca from extracellular fluid. Damaged cardiac muscle is repaired by fibrosis. no satellite cells in cardiac tissue. not much mitosis.

ganglion

knot-like swelling in a nerve where the cell bodies of neurons are concentrated.

short-term (STM)

lasts from a few seconds to a few hours. info stored in STM may quickly forgotten if we stop mentally reciting it, we are distracted, we remember something new. working memory is a form of short term memory, that allows us to hold an idea in our mind long enough to carry out an action,such as calling a phone number we just looked up, working out steps in a math problem, or looking for keys while remembering where you have already looked. uses circuit of facilitated circuits.

Absolute refractory period

lasts from start to end of the action potential until the membrane returns to the resting potential. (for as long as the Na+) channels are open and subsequentaly inactivated.

Action Potential

more dramatic change produced by voltage-gated ion channels in the plasma membrane. they occur only when theres a high enough density of voltage gated channels. most soma only have 50-75 channels per square micrometer and cant generate action potentials. if excitatory local potential spreads all the way to the trigger zone and still going strong enough when it arrives, it can open the channels and generate action potential 1. RMP 2. Local potential 3. Depolarization 4.repolarization 5. hyperpolariz

astrocytes

most abundant glial cell in the CNS, ovwer 90% of tissue in some areas of the brain. cover entire brain surface and most non-synaptic regions of the neurons in the gray matter of the CNS. named for their starlike shape. thier functions are: -form a supportive framework for nervous tissue -have extensions called perivascular feet which contract the blood capillaries and stimulate them to form tight protective seal (blood-brain barrier) -monitor neuron activity and regulate blood flow in the brain tissue to meet changing needs for oxygen and nutrients -convert blood glucose to lactate and supply this to neurons -secrete nerve growth factors that regulate nerve development -communicate electrically with neurons and influence synaptic signaling -regulate composition of tissue fluid. when neurons transmit signals, they release neurotransmitters and potassium ions, arystrocytes absorbe these and prevent them from reaching excessive levels in tissue fluid -astrocytes form hardened scar tissue and fill space formerly occupied by neurons called sclerosis

brainstem

most ascending and descending tracts either begin or end here.

What happens when a nerve signal reaches the end of the axon?

most cases it triggers the release of a neurotransmitter that stimulates a new wave of electrical activity in the next cell across the synapse.

mixed fibers

most common, have both afferent and efferent fibers and conduct signals in two different directions. one fiber directs signals and the other conducts signals. most neves that are labeled motor are actually mixed because they carry signals of preception back to the CNS.

labeled line code

most important mechanism form of transmitting QUALITATIVE info. this code is based in the fact that each nerve fiber from the brain leads from a receptor that specifically recognizes a particular stimulus type. for example optic nerves carry signals only from light receptors in the eye; these fibers never carry info. about taste and sound, so the brain only interprets these signals in terms of light. each nerve fiber to the brain is a line of communication "labeled" or recognized by the brain as representing a particular stimulus quality. pitch of sound sour or sweet taste color of light

descending

motor impulses down the cord.

Axonic neurons

multiple dendrites but no axon. communicate locally through dendrites and do not produce action potentials. some are found in the brain, retina, and adrenal medulla. in retina they help in visual processes such as the perception of contrast.

how does potassium effect RMP

potassium ions have the greatest influence on the RMP because the plasma membrane is more permeable to potassium and any other ion, as a result the ICF becomes more and more negative, but the positive potassium ions now have a stronger attraction and attracts some of them back into the cell. eventually equilibrium is reached in which K+ is moving out of the cell (down concentration gradient) and into the cell (electrical attraction) at equal rates. there is no further diffusion of K+at the the point of equilibrium, K+ is about 40 times as concentrated in the ICF as in the ECF

aerobic respiration

produces more ATP, and NO lactic acid. but requires continual supply of oxygen. uses glucose and organic compounds to extract energy . in most resting muscle ATP is generated by aerobic respiration of fatty acids. during exercise many forms of ATP synthesis are used depending on exercises duration.

myelination

production of myelin sheath, begins in the 14th week of fetal development, yet hardly any myelin exists in the brain at time of birth. myelination proceeds rapidly in infancy and isnt completed until late adolescence. since myelin has such a hogh lipid count dietary fat is important to babies nervous system development. it is best not to give children under 2 low-fat diets (skim milk).

Fatigue

progressive weakness and loss of contractility that results from prolonged use of muscles. this will happen for example if you hold a book out for a minute, you will feel your muscles growing weaker and eventually you wont be able to hold it up.

tendon organs

proprioceptors located in a tendon near its junction with a muscle. A tendon organ is about .5 mm long. it consists of an encapsulated bundle of small loose collagen fibers and one and one or more nerve fibers that penetrate the capsule and end in flattened leaf like processes between collagen fibers are slightly spread and put little pressure on the nerve endings. when muscle contraction pulls on the tendon, the collagen fibers come together like two sides of a stretched rubber band and squeeze the nerve endings between them.

tropomyosin

protein located in thin filaments, when a muscle fiber is released , each tropomyosin blocks the active sites of six or seven G actin and prevents myosin from binding to the G actin. tropomyosin has small calcium binding proteins that are bound to it called torponin

ACh Receptors

proteins incorporated into its plasma membrane across from the synaptic knobs, in order to increase ACh receptors (making sensitivity increase), sarcolemma in the area has numerous junction folds(increase surface area of ach sensitive membrane).

what is the other way of encoding a stimulus? (other than recruitment and labeled line code)

quantitative, it depends on fact that the more strongly a neuron is stimulated, the more frequently it fires. weak stimulus may cause a neuron to generate 6 action potentials per second but a strong stimulus 600 per second. the CNScan judge stimulus strength from the firing of afferent neurons. there is a limit to the amount of times a neuron can fire set by the absolute refractory period. the higher the frequency, the more action potentials. the highest frequency fires 500-1,000 per second.

flexor reflex arc

quick contraction of flexor muscles resulting in withdrawal of a limb from an injurious stimulus. ex. walking in lake and step on glass, you unconsiously pull foot up before glass goes deeper in the foot. this action involves contraction of the flexors and relaxation of the extensors and relaxation of the extensors in that limb. post synaptic reflex- pathway in which signals travel over many synapses on their way back to the muscle.

what are the qualities of reflexes?

quick, involuntary, stereotyped. reactions of glands or muscles to stimulation.

end-plate potential (EPP)

rapid fluctuation in voltage at the motor end plate

Oligodendrocyte in the CNS

reach out to myelinate several nerve fibers in its immediate vicinity. because it is anchored to multiple nerve fibers, it cannot migrate around any one of them like a Schwann cell does. it pushes new layers of myelin under the old ones so myelination spirals inward toward the nerve fiber. they have no neurolemma or endoneurium

gray matter

relatively dull in color, contains LITTLE MYELIN. contains somas, dendrites, and proximal parts of axons in neurons. site of synaptic contact between neurons and therefor the site of all integration in the spinal cord. its located on the inside of spinal cord. contains two posterior horns, and two anterior horns, right and left side are connected by gray commissure, in the middle of the commissure is the central canal (collapsed in most places in adults). also spinal nerve branches to posterior and anterior roots.

Ependymal cells

resemble a cuboidal epithelium lining the internal cavities of the brain and spinal cord. they have no base unlike true epithelial cells. they exhibit root like processes that penetrate into underlying tissue. they produce CEREBROSPINAL FLUID (CSF). a liquid that bathes the CNS and fills its internal cavities, they have patches of cillia on their apical surfaces that help to circulate the CSF ependymal cells.

Local potentials

stimulation of a neuron causes local disturbances in membrane potential. typically, the response begins at a dendrite, spreads through the soma, travels down the axon, and ends at the synaptic knob. various neurons can be stimulated by chemicals, light, heat, or mechanical forces. the example of neurons being chemically stimulated, the chemical perhaps a pain signal from damaged tissue or odor molecule in a breath of air.-binds to receptors on the neuron. this opens sodium channels that allow sodium to flow into the cell. sodium inflow cancels some of the inernal negative charge, so the voltage across the membrane drifts tward zero.

muscle spindle

stretch receptor, many somatic reflexes involve it. they are embedded in the muscle. function is to inform the brain of muscle length and body movements. enables the brain to send motor commands back to the muscles that control muscle tone, posture, cordinated movement, and corrective reflexes. (balance) they are abundant in muscles that use fine control like the hand. concentrated in the ends of msucles near its tendon. they are contained in a fibrous capsule. one of the bodies proprioceptors (sense organs specialized to monitor the position and movement of body parts.

cardiac muscle

striated and involuntary only located in the heart

Skeletal muscle

striated and voluntary

incomplete tetanus

stronger tension every time, without full relaxation between twitch

satellite cells

surround somas in ganglia of the PNS. provide insulation around soma and regulate the chemical environment of the neurons.

inhibitory GABA-ergic

synapse that employs y-aminobutyric acid (GABA), as a neurotransmitter. Amino acid neurotransmitters work by its neurotransmitter. Amino acid neurotransmitters work by the same mechanism as ACh-binding to ion channels and causing immediate changes in membrane potential. the release of GABS and binding to its receptor, however are simmilar to the preceding case of ACh. but one difference is that the GABA receptor is a chloride channel. when it opens Cl- enters the cell and makes the inside even more negative than the resting membrane potential. the neuron an inhibitor.

structure of chemical synapse

synaptic knob (contains synaptic vesicles, that are ready to release neurotransmitter at command), a reserve pool of synaptic vesicles are tethered to they cytoskeleton farther away from the membrane. postsynaptic neurons dont show specializations. at this end there are no synaptic vesicles and cant release neurotransmitters. but it does have neurotransmitter receptors and ligand gated channels

neural coding

they way in which the nervous system converts info into a meaningful pattern of action potentials. the nervous system must interpret and pass along both quantitative and qualitative info. about the environment. taste, light, seeing color, sound, ect. considering the complexity of info., to be comunicated about the conditions around us, its a wonder that it can be done and only by using action potentials. since all the nneurons of an action potential are identical. also called sensory coding when it happens in the sensory organs.

what are the three kinds of myofilaments

thick, thin, and elastic

perimysium

thicker connective tissue sheath, wraps muscle fibers together in bundles called fascicles. carries the larger nerves and blood vessels as well as stretch receptors called spindles. separate fascicle

endomysium

thin sleeve of loose connective tissue that surrounds each muscle fiber. creates room for capillaries and nerve fibers to reach every muscle fiber, ensuring that no muscle cell is without stimulation and nourishment. associated with nerve endings, excitation of muscle fiber is based on exchange on sodium, potassium, and calcium ions between endomysial tissue fluid

action potential

this quick up and down volt shift from negative RMP to positive value and then back to the RMP again, this resting potential voltage is typically seen in a waiting cell, in an active stimulated cell voltage is fluctuating quickly, action potentials at one point on plasma membrane causes another one to happen immediately in front of it, and so on like a wave

myogram

timing and strength of a muscle can be shown in this chart.

Myokinase

transfer phosphate from one ADP to another, converting the latter to ATP

regulatory proteins

tropomyosin and troponin are this kind of protein because they act like a switch, determining when the fiber can contract and when it cant

types of smooth muscle

two extreme types, multiunit and single unit. MultiUnit-occurs in the larger arteries and air passages, piloerector muscles and eye muscles that control iris and lens. its innervation is autonomic is somewhat similar to skeletal- terminal branches of a nerve fiber synapse with individual myocytes and form a motor unit. does not generate action potentials. contracts in response to electrical changes in sarcolemma or absence of electrical excitation Single Unit smooth muscle- more common, occurs in most blood vessels and in digestive, respiratory, urinary, and reproductive tracts. also called visceral muscle. forms aforementioned layers in many hollow viscera. myocytes of this type of msucle are electrically coupled to eachother by gap junctions. allows direct stimulation numerous cells contract as a unit. almost as if they were a single cell. associated with single myocyte but stimulate several at once when they realease neurotransmitter.

wave summation

two stimuli arriving close together. because it results from one wave of contraction added to another. wave upon wave each twitch reaches a higher tension every time and the muscle only relaxes partially

Nissl Bodies

unique to neurons, and helpful clue to identifying them in tissue sections with mixed cell types

pacemaker

unlike skeletal muscle, there is no need for nervous stimulation for contraction in cardiac muscles. heart has a built in pace-maker. this rhythmically sets off a wave of electrical excitation. wave travels through muscle and triggers the contraction of the heart chambers. heart is autonomic because it can contract rhythmically and independitly contract. autonomic nervous system can stimulate by increasing and decreasing heart rate and contraction. cardiac doesnt exhibits quick twitches like skeletal muscle . uses aerobic respiration rich in myoglobin and glycogen and had especially large mitochondria fill 25% of the cell compared with smaller mitochondria has 2% of skeletal muscle fiber. adaptable with respect to the fuel used vulnerable to interuptions in oxygen supply uses anaerobic fermintation, highly resistant to fatigue

smooth muscle

unstriated and involuntary

fast and slow fibers in a muscle

usually there are both fast and slow fibers but usually one is more predominant than the other determined by the function of the muscle. quick motility and reflexes, or sustained weight bearing tension.

signal conduction of myelinated fibers

voltage gated ion channels are scarce in the myelin covered internodes- 25 compared to the 2,000 in the nodes of ranvier. there would be little point in having ion channels in the internodes because myelin insulates the fiber from the ECF at these points, Na+ from the ECF could not flow into the cell even if more channels were more channels were present. so no action potential can occur in the internodes, and the nerve signal requires some other way of traversing the distance from one node to the next. NA+ enters the axon at node of ranvier and diffuses a short distance along the inner face of the membrane, Na+ act as magnets repelling each other, this energy transfer travels down the axon much faster further than any of the individual ions. signal grows weaker with distance because axoplam resists movement of the ions and because sodium leaks out of the axon along the way. with distance there is a lower and lower concentration of sodium to relay the charge on.

skeletal muscle

voluntary, striated muscles, attached to muscle or bone. has alternating light and dark transverse bands called striations.

stretch reflex

when a muscle is suddenly stretched it "fights back" it contracts, increases tone, and feels stiffer that an unstretched muscle. helps maintain equilibrium and posture this happens for example when your head falls forward or the rocky boat example. they often feed back not to a single muscle but to a synergist or antagonist. without stretch reflexes movements tend to be jerky. a stretch reflex is mediated by the brain and os not therefor strictly a spinal reflex but a weak component of it is spinal and occurs even if the spinal cord is severed from the brain. this happens in the reflexive contraction of a muscle when its tendon is tapped (patellar reflex)

motor Unit

when a signal approaches its axon it spreads to all of the branched muscle fibers its touching and stimulates all of them, makes muscle fibers contract in unison. one nerve fiber and all the muscle fibers connected are called motor unit, motor unit's muscle fibers are dispersed to create a weak contraction, need multiple motor units simultaneously to make a contraction. they work in shifts so they don't fatigue due to too much stimulation and the muscle can sustain contraction longer

contraction phase of a twitch

when elastic components are taunt, muscles begin to produce external tension and move a resting object, or load like a body limb like a rubber band (when new not taunt then when stretched external tension would be lifting it). this phase is very short (on myogram). entire twitch lasts about 7-100 ms can complete 10-100 twitches per sec.

contralateral and ipsilateral

when origin and destination are on opposite sides of the body, it is called contralatera. when a track doenst decussate, snd origin and destination are on the same side, it is called ipsilateral.

short term energy

when phospagen system becomes exhausted, muscle transitions from anaerobic to buy time until cardio and resperitory can catch up with muscles oxygen demand. during this period muscles must maintain glucose from blood and their own stored glycogen. for every glucose consumed there is a net gain of 2 ATP it converts the glucose to lactic acid (glycogen-lactic acid system), enough ATP for 30-40 seconds of maximum activity basket ball or running around a baseball dimond

neromuscular junction (NMJ)

when target cel is a muscle fiber, the synapse can also be called this aka motor end plate

muscle relaxation

when the nerve fiber stops stimulating it, a muscle fiber relaxes and returns to its resting length. relaxation alone doenst return muscle to its resting length. must be achieved some force pulling the muscle and stretching it.