Presentation on theme: "Sensory and Motor Mechanisms"— Presentation transcript:
1 Sensory and Motor Mechanisms Chapter 49Adrianna Wurster , Katrina Gladstone, Hannah Reed
2 Sensing and ActingOrigins of sensing can be traced back to the appearance, in prokaryotes, of cellular structures that sense pressure or chemicals in the environment and then direct movementDetection and processing of sensory information and the generation of motor output provide the physiological basis for all animal behaviorWhen animals are in motion they are probing the environment through motion, sensing changes and anticipating the next action. This is a continuous cycle.
3 Sensory receptorsSensory receptors- transduce stimulus energy and transmit signals to the central nervous systeminfo transmitted through the nervous system in the form of nerve impulses or action potentials, all or none eventswhat matters is where action potentials go, not what triggers themsensations- action potentials that reach the brain via sensory neuronsperceptions- interpretation of senses by the brainSensations and perceptions begin with sensory reception which is the detection of a stimulus by a cell. Most are specialized epithelial cells.Exteroreceptors- sensory receptors that detect stimuli coming from outside the bodyInteroreceptors- detect stimuli coming from within the body, such as blood pressure and body position
4 Functions Performed by Sensory Receptors All stimuli represent forms of energyFour Functions:sensory transductionamplificationTransmissionintegration
5 Sensory Transductionsensory transduction- the conversion of stimulus energy to a change in the membrane potential of a sensory receptorReceptor potential- change in membrane potential itselfreceptor potentials result from opening or closing of ion channels in the sensory receptor plasma membrane caused by bending and stretching of the membrane by external stimulisensory receptors are extremely sensitive
6 AmplificationThe strengthening of stimulus energy by cells in the sensory pathwaySome amplification occurs in sensory receptors and signal transduction pathways .It can take place in accessory structures of complex organs
7 Transmissiontransmission- energy stimulus has been transduced into a receptor potential, action potentials are transmitted to the central nervous systemif cell cannot generate action potentials themselves, these receptors release neurotransmitters at synapses with sensory neuronsreceptors release an excitatory neurotransmitter, causing the sensory neuron to transmit action potentials to the central nervous systemmagnification of a receptor potential affects the frequency of action potentials that travel as sensations to the central nervous systemmany sensory neurons spontaneously generate action potentials at a low rate
8 Integration process begins as soon as information is received sensory adaptation- decrease in responsiveness during continued stimulationintegration occurs at all levels within the nervous systemcomplex sensory structures such as the eyes have higher levels of integration
9 Types of Sensory Receptors MechanoreceptorsChemoreceptorsElectromagnetic receptorsThermoreceptorsPain Receptors
10 MechanoreceptorsMechanoreceptors- sense physical deformation caused by stimuli such as pressure, touch, stretch, motion, and sound (mechanical energy)EX: crayfish stretch cell receptor and vertebrate hair cell are mechanoreceptorsMuscle Spindles- a mechanoreceptors stimulated by mechanical distortionWhen muscle fibers are stretched, spindle fibers are stretched, depolarizing sensory neurons and triggering action potentials that are transmitted to the spinal chordMammalian sense of touch relies on mechanoreceptors, the dendrites of sensory neuronsEmbedded in layers of connective tissueLocation of receptor depends on function
12 ChemoreceptorsChemoreceptors- both general receptors that transmit information about the total solute concentration of a solution and specific receptors that respond to individual kinds of moleculesex: osmorecpetors in the mammalian brain – detect solute concentration of the blood and stimulate thirst when osmolarity increases
13 Two of the most sensitive and specific Chemoreceptors known are in the antennae of the male silkworm moth
14 Electromagnetic receptors detect various forms of electromagnetic energy, such as visible light, electricity, and magnetismPhotoreceptors detect the radiation of visible lightSnakes have sensitive inferred receptors that can detect the body heat of upcoming prey.The platypus has electroreceptor on its bill that detect electric fields generated by the muscles of crustaceans.Snake vision.
15 Thermoreceptorsrespond to heat or cold, help regulate body temperatureThere is controversy whether they are modified pressure receptors or if they are naked dendrites of certain sensory neurons
16 Pain Receptors naked dendrites in the epidermis and dermis Usually leads to defensive reactionDifferent groups of pain receptors respond to excess heat, pressure, or specific classes of chemicals released from damaged or inflamed tissuesProstaglandins increase pain by sensitizing receptors
17 Sensing gravity and sound in invertebrates statocysts: sensory organs containing mechanoreceptors; function in sense of equilibriumstatoliths: dense granules surrounded by layer of ciliated receptor cells in a statocyst; moved by gravity and stimulates certain cellsindicate body positioninsects have body hairs that vibrate in response to sound waves and localized “ears” (tympanic membrane stretched over air chamber
18 Hearing and equilibrium in mammals tympanic membrane bonesoval windowcochleabasilar membraneauditory nerve brainsound is represented by changes in frequency sensations in auditory nervevolume: amplitudepitch: frequency
20 Equilibriumutricle: detects body position/balance; hair cells and “ear stones”saccule: detects body position/balanceclustered hair cells in gelatinous material with otoliths (ear stones, move with gravity); releases neurotransmitters interpreted by brain; disrupted during spinning
21 How the Cochlea distinguishes pitch: Variation in the width and stiffness of the basilar membrane (pink) tunes specific regions of the membrane to a specific frequencyDifferent frequencies cause different places along the membrane to vibrate stimulating particular hair cells and sensory neurons.
22 Hearing and equilibrium in other vertebrates have inner ears located near brain, saccule, utricle, semicircular canals, homologous structures to equilibrium sensorsno cochleaotoliths in inner ear chamber stimulate sensory hairsno eardrum – does not open outside body (vibrations in water from sound wavesskeletoninner earotolithslateral line system: along both sides of body, contain mechanoreceptors tht detect low frequency wavesneuromasts: hair cells embedded in cupulahelps perceive movement through waterterrestrial vertebrates: inner ear evolved
23 Sense of taste and smell are closely related in most animals pheromones- chemical converstationsgestation (taste); olfaction (smell)Taste in humansreceptor cells are modified epithelial cells organized into taste budssweet, sour, salty, bitter, umami – detected by chemoreceptorsSmell in humansciliaolfactory receptor cellolfactory bulb in brainstrong link to taste
24 Similar mechanisms underlie vision throughout the animal kingdom all photoreceptors have light absorbing pigments and most are homologousVision in invertebratesocellus: detects light intensity and direction (eyespot/eyecup)image forming eyes:compound eyes; several thousand light detectors (ommatida)single-lens eye: camera-like
25 The vertebrate visual system camera-likeStructure of the eyesclera: white, outer layer of connective tissuechoroid: thin, pigmented inner layerconjunctiva: mucous membrane over scleracornea: fixed lens; lets light iniris: color, regulates light entering pupilpupil: hole in irisretina: contains photoreceptorsrods and cones (no rods on fovea)lens/ciliary body; divides cell into two cavitiesaccommodation: changing shape of lens to focusaqueous humor: liquid filling anterior cavityvitreous humor: jelly filling posterior cavity
26 Sensory transduction in the Eye rhodospin: retinal (light absorbing molecule) bonded to ospin (protein)photospins: three visual pigments of cones (red, green, blue)
27 Processing visual info depolarized and hyperpolarized rods and cones release neurotransmitters (glutamate) at synapsesganglion cells, horizontal cells, amacrine cellslateral inhibition: sharpens edges and enhances contrastoptic chiasm: where two optic nerves meet near the center of the base of the cerebral cortex
28 Evolution of the Skeletal system Dermoskeleton – the most primitive vertebrate system and the earliest to show mineralization within the vertebrate phylogenyThis early mineralized bone was known as “aspidin” . It is dominated by an organic matrix and collagen fibersOstostracans exhibited the first evidence of cellular bonePlacoderms are the earliest group to show systematic remodeling of the skeleton.Cartilage and bone developed the endoskeleton separately from this evolutionary pattern and had an unmineralized origin.Acraniate chordate Branchiostoma – cartilaginous elements used for support in hagfish, lamprey and some fins of early fishCalcified cartilage arose from the neruocranium of primitive animalscartilage template may undergo hypertrophy and eventually be replaced by bone, a process termed endochondral ossification.
30 Types of Skeletons and Their Functions Functions: Support, Movement, Protection, homeostasis, storageSupport – without the structure of the skeletal system, humans would sag from the weight of their bodyProtection – the skeleton protects soft tissues (organs) ex. ribs and sternum protect the heart and lungs, - skull protects the brainMovement - give the muscles something to work against. skeletal muscle is attached to bone so it pulls on the bone when it contractsMineral homeostasis - stores calcium and phosphorus--minerals are released into the blood when neededBlood cell production - red bone marrow produces red blood cells, white blood cells and other blood elementsStorage - storage of minerals and lipids(fats)---yellow marrow stores fat --(found in long bones)
31 Types of SkeletonsHydrostatic skeletonsExoskeletonsEndoskeletons
32 Hydrostatic SkeletonFluid held under pressure in a closed body compartmentFound in cold-blooded organismsDominant skeleton in cnidarians, flatworms, nematodes and annelidsAnimals control their form and movement by using ,muscles and pressure to change the shape of the fluid filled compartmentsEX: hydra can elongate by closing its mouth and using contractile cells in the body to constrict the gastrovascular cavity - it results in thrashing movementsThe earthworm’s skeleton is the coelomic fluid . They use thir skeleton for peristalsisIt is a type of movement on land that produces rhythmic waves if muscle contractions from front to backHydrostatic skeletons are better suited for aquatic life because they cushion internal organs from shocks and provide support for crawling in terrestrial animals.
34 Exoskeleton Hard encasement deposited on the surface of an animal Have a calcareous shell - calcium carbonate shellAs an animal grows, it enlarges its shell by adding to the outer layers of the pre- existing shellsEx. MollusksThe jointed exoskeletons of arthropods is the cuticle> a nonliving coat secreted by the epidermis.The cuticle is made up of chitin used for strength and flexibility.It must be thin and flexible like leg joints for movementArthropods shed their exoskeleton (molt) to produce a larger one
35 EndoskeletonHard supporting elements (bones) buried within the soft tissues of animalsSponges have hard spicules made of proteinEchinoderms have hard plates called ossicles under the skinChordates have a skeleton consisting of bone, cartilage, or a combination of the twoMammalian skeleton consists of over 200 bones that can be fused together or connected by joints.There are two parts of the skeleton:Appendicular skeletonLimb bonesPectoralPelvic girdlesAnchor the appendages to the axial skeletonJoints provide flexibility for body movementAxial skeletonSkullBackboneRibcage
36 1 Ball-and-socket joints, where the humerus contacts the shoulder girdle and where the femur contacts the pelvic girdle, enable us to rotate our arms and legs and move them in several planes.2 Hinge joints, such as between the humerus and the head of the ulna, restrict movement to a single plane.3 Pivot joints allow us to rotate our forearm at the elbow and to move our head from side to side.keyAxial skeletonAppendicular skeletonSkullShoulder girdleClavicleScapulaSternumRibHumerusVertebraRadiusUlnaPelvic girdleCarpalsPhalangesMetacarpalsFemurPatellaTibiaFibulaTarsalsMetatarsals1Examples of joints23Head of humerus
37 MusclesIn addition to the skeleton, muscles and tendons also support large land vertebratesAnimal movement is based on contractile systems that expend energyThe action of muscles is always to contract therefore the ability of muscles to move parts of the body in opposite directions requires them to be attached to the skeletonAttached in antagonistic pairs where each member of one pair works against the otherEX: biceps and tricepsHumanGrasshopperBiceps contractsTriceps relaxesForearm flexesBiceps relaxesTricepscontractsForearm extendsExtensor muscle relaxesFlexor muscle contractsTibia flexesExtensor muscle contractsFlexor muscle relaxesTibia extends
38 Types of MuscleSkeletal muscle – attached to bones and causes movements of the bodySmooth Muscle – lines the walls of blood vessels and the digestive tract where it advances the movement of other objects through a slow processCardiac Muscle – responsible for rhythmic contractions of the heart.Consists of cells with gap junctions to allow for electrical synapses
39 Vertebrate skeletal muscle Skeletal muscle is responsible for movement and is characterized by a hierarchy of smaller and smaller unitsA skeletal muscle consists of a bundle of long fibersRunning parallel to the length of the muscleA muscle fibera bundle of smaller myofibrils arranged longitudinallyComposed of 2 types myofillamentsThin Filaments - consisting of two strands of actin and one strand of regulatory proteinThick Filaments - staggered arrays of myosin moleculesSkeletal muscle is also called striated muscle because the regular arrangement of the myofilaments creates a pattern of light and dark bands
40 The borders of the sarcomere are called the z line MuscleBundle of muscle fibersSingle muscle fiber(cell)Plasma membraneMyofibrilLight bandDark bandZ lineSarcomereTEM0.5 mI bandA bandM lineThick filaments (myosin)Thin filaments (actin)H zoneNucleiThe repeating units are called sarcomeres which are the basic contractile unit of the muscleSarcomeres are composed of long, fibrous proteins that slide past each other when the muscles contract and relaxThe borders of the sarcomere are called the z line
41 Z lines make up the border of sarcomeres > actin is attached here I band is the area near the end of the sarcomere where the thin actin filaments are locatedThe A band is considered the length of the thick myosin fillamentsDuring muscle contraction the length of the sarcomere is reduced- actin filaments slide over the myosinThis is the sliding Filament model where the thick and thin filaments slide past each other so that the degree of overlap increases
42 The Neuromuscular Junction A motor neuron will cause a muscle fiber to contract – the depolarization causes the neurotransmitters to be released into the synapse of the neuromuscular junction1. Action potential generates the release of acetylcholine2. The impulse is sent along sarcolemma and throughout the T tubulesThe sarcolemma is the plasma membrane of the muscle callThe t tubules permeate the cell3. Sarcoplasmic reticulum releases Ca2+The sarcoplasm is the cytosol of the cell and holds the calcium- storing SR4. Myosin cross bridges form – the Ca2+ released binds with troponin to expose binding sites for myosin cross- bridge formation.The availability of ATP begins the muscle contraction
43 Summation and TetanusA single action potential in a muscle will cause the muscle to contract for a few milliseconds and then relaxCalled a twitchIf a second action potential comes before the first impulse is over the contraction will be largerThe summation effectA series of overlapping action potentials creates a larger summation and therefore a larger contractionIf the rate of stimulation is fast enough, the twitches will become one smooth contraction called a tetanus (nothing to do with the shot)A tetanus is what occurs when a large muscle (biceps) contractThe muscle will eventually fatigue after a period of prolonged contraction
45 Diseases Polymyositis an uncommon connective tissue disease with muscle inflammation and skeletal muscle system weakness.diagnosed most often in adults from 40 to 60 years of age or in children ages 5 to 15 years. .signs and symptoms include:Progressive muscle weaknessDifficulty swallowing (dysphagia)Difficulty speakingMild joint or muscle tendernessFatigueShortness of breathThere is no exact cause of this disease but studies show that men are less likely to be affected than women.Treatment: there is no known cure but the use of drugs and therapy can increase muscle strengthCorticosteroid - to reduce muscle inflamation
46 Diseases continued..Stargardt’s Diseasejuvenile macular degeneration, affects approximately one in 10,000 people and is characterized by central vision loss early in lifeCausesStargardt's is an inherited disease passed along to children when both parents carry mutations of a gene associated with vitamin A processing in the eye.SymptomsDeterioration of vision as a childClouding of the corneaLoss of color visionTreatment and curesStem cell research to replace damaged tissueCounter form of vitamin A to slow the formation of Vitamin A dimmers
47 Diseases continued.. Otitis Externa the skin of the ear canal becomes inflamed.Can result fromscratching the lining or your outer ear canala skin condition such as eczema,fungal infection from swimmingSymptoms :itchinesswatery discharge.The discharge may dry overnight around the outside of the ear.Little hearing lossTreatments:AntibioticsEar drops
48 Science, Technology, and Society Hearing aid - a device typically worn inside or behind the ear that amplifies sound for use by people who cannot hear well.Bionic Eye – in development by NASA. Used to repair damaged rods and cones with a ceramic implant detectors
49 InterdependenceGas exchange – the muscles enable the diaphragm to move allowing air into the lungsDigestion – bone and muscle move the jaw to break down the foodNervous - involved in movement. Brain and nerves direct muscles to contract. Sensory organs are the first input of a stimulusCardiovascular – cardiac muscles contract to pump blood to the heart and around the bodyEndocrine- hormones secreted directly correlate with muscle and bone growth
50 Works citedBentler, Ruth A."Hearing aid." World Book Advanced.World Book,2012.Web.20 April 2012.Campbell, Neil A. and Reece Jane B . Biology “Seventh edition” .Pearson Education; Benjamin Cummings . New York: Print.Columbia researchers work on preventing blindness from age-related macular degeneration and Stargardt's disease. Columbia University Medical Center. Press release. May 2011.DenisonRH “The Early History of the Vertebrate Calcified Skeleton”. Clin Orthopedics. Print.Mayo clinic staff. “Polymyocitus” The Mayo Clinic. Mayo Foundation for Medical Education and Research (MFMER) Web April 2012.