Sensory Organs - Chapter 17 PDF

SENSE ORGANS - Ch.17 Are there others? Will cover some, but not all of this. SENSE ORGANS - Ch.17 Are there others? YES! Electroreception Lateral Line “distant touch”...

SENSE ORGANS - Ch.17 Are there others? Will cover some, but not all of this. SENSE ORGANS - Ch.17 Are there others? YES! Electroreception Lateral Line “distant touch” Echolocation (Sonar) drones in dark SENSE ORGANS - Ch.17 Are there others? YES! OSTEOSTRACANS > Unknown sense organ.  SENSE ORGANS - Ch.17 Will cover some, but not all of this. RECEPTORS - Where is all begins……. Specialized cells for monitoring the environment (enhanced capabilities). Can be as simple as a free nerve ending.  SENSE ORGANS - Ch.17 Will cover some, but not all of this. RECEPTORS - Where is all begins……. Specialized cells for monitoring the environment (enhanced capabilities). Can be as simple as a free nerve ending. Act as transducers: Convert one energy to another. Generally modified to respond to specific stimulus (light, pressure, taste, etc.).  SENSE ORGANS - Ch.17 RECEPTORS - Where is all begins……. Specialized cells for monitoring the environment (enhanced capabilities). Can be as simple as a free nerve ending. Act as transducers: Convert one energy to another. Generally modified to respond to specific stimulus (light, pressure, taste, etc.). Generate nerve impulse. All signals carried same way through body. Brain formulates as specific sense. Synesthesia - mix up of senses (hear orange, thursday = brown, etc…) most common - #’s, letters, time evoke colors RECEPTORS - Types of receptors: Chemoreceptors. Cutaneous receptors. (mechanoreceptor) Proprioceptors. (mechanoreceptor) Photoreceptors. Thermoreceptors CHEMORECEPTORS - Four locations: 1. Arteries & 4th ventricle (brain); detect [O2], [CO2] in blood, cerebrospinal fluid. CHEMORECEPTORS - Four locations: 1. Arteries & 4th ventricle (brain); detect [O2], [CO2] in blood, cerebrospinal fluid. 2. Mucous membranes; detect noxious agents. CHEMORECEPTORS - Four locations: 1. Arteries & 4th ventricle (brain); detect [O2], [CO2] in blood, cerebrospinal fluid. 2. Mucous membranes; detect noxious agents. 3. Olfactory tissues (nasal sac) 4. Gustatory tissue (oral & pharyngeal cavities, skin). Olfactory vs Gustatory = Fine line between the two in aquatic vertebrates. CHEMORECEPTORS - OLFACTORY Similar in all vertebrates. From paired ectodermal placodes - nasal sacs. CHEMORECEPTORS - OLFACTORY Similar in all vertebrates. From paired neurogenic placodes - nasal sacs. Simple: 1) Neuron sits in epithelium with dendrites exposed at surface. +/- non-motile cilia for added surface area. 2) Axon runs to olfactory bulb of brain. ∑ axons = olfactory nerve. Odorants bind to plasma membrane of cilia and initiate response. Humans ~10,000 different odors. How? Likely, suite of receptors that in combination serve to generate distinct odors. 2 1 2 1 CHEMORECEPTORS - OLFACTORY Humans ~10,000 different odors. How? Likely, suite of receptors that in combination serve to generate distinct odors. landmine-sniffing rat CHEMORECEPTORS - OLFACTORY Sensory adaptation - smell adapts quickly. CHEMORECEPTORS - OLFACTORY - specializations Agnathans only one nostril. Gnathostomes (except sarcopterygia): nasal sac with incurrent and excurrent Dogfish Lamprey CHEMORECEPTORS - OLFACTORY - specializations Hagfish only one nostril. Gnathostomes except sarcopterygia: nasal sac with incurrent and excurrent Sarcopterygia (lungfish + tetrapods) Nasal passage connects to oral cavity/pharynx. CHEMORECEPTORS - OLFACTORY - specializations Hagfish only one nostril. Gnathostomes except sarcopterygia: nasal sac with incurrent and excurrent Sarcopterygia (lungfish + tetrapods) Nasal passage connects to oral cavity/pharynx. Mammals, birds with turbinates. Increases surface area and olfactory epithelium. (respiratory vs sensory) Important for endothermy. But arboreal and volant forms generally reduce sense of smell. Best smelling birds are vultures and kiwis. sensory respiratory CHEMORECEPTORS - OLFACTORY - VOMERONASAL ORGAN Most tetrapods exclusive of aquatic forms, flyers (birds, bats) & humans. Olfactory epithelium forms pair of sac-like organs on roof of mouth. Cilia replaced by microvilli. Forked tongue of some squamates delivers to organs. CHEMORECEPTORS - OLFACTORY - VOMERONASAL ORGAN Most tetrapods exclusive of aquatic forms, flyers (birds, bats) & humans. Olfactory epithelium forms pair of sac-like organs on roof of mouth. Cilia replaced by microvilli. Forked tongue of some squamates delivers to organs. Flehmen response - mammals Curling of upper lip activates organ. Important in pheromone detection. CHEMORECEPTORS - GUSTATION - taste. Detected by taste buds. Barrel-shaped clusters of 20-30 receptors + sustentacular cells. Far less sensitive than olfactory tissue. Need greater concentrations, direct contact. Endodermal in origin. Taste cells with microvilli. Short life, ~ 1 week. CHEMORECEPTORS - GUSTATION - taste. Detected by taste buds. Barrel-shaped clusters of 20-30 receptors + sustentacular cells. Far less sensitive than olfactory tissue. Need greater concentrations, direct contact. Endodermal in origin. Taste cells with microvilli. Short life, ~ 1 week. In oral cavity - Facial (VII) Pharynx - Glossopharyngeal (IX),Vagus (X). As with smell, taste combination of receptor types + brain projection (olfactory, tactile inputs). Taste buds on the skin of many fish and amphibians (e.g. catfish). CUTANEOUS RECEPTORS All verts with free nerve endings in dermis (+ perhaps epidermis). Activated by vibrations, touch, injuries, temp, etc. Alert to injuries. Some in mouth and eyeball. CUTANEOUS RECEPTORS Mammalian skin Variety of touch and pressure receptor w/in + just below dermis. Examples: Merkel’s disks - NCC in origin! Meissner corpuslces Ruffini endings Pacinian corpuslces These vary in location and whether layered/laminated or not. Covered = adapt rapidly, note start/end. Others adapt slowly, remain active. CUTANEOUS RECEPTORS Mammalian skin Variety of touch and pressure receptor w/in + just below dermis. Examples: Merkel’s discs - pressure, tactile (NCC origin). Meissner corpuslces Ruffini endings Pacinian corpuslces Associated w/ hair; neuron wraps around. Hair acts as lever arm. Slight movement. Vibrissae respond to slight touch or air movement. PROPRIOCEPTORS In muscles, tendons, joints - often modified muscle fibers. Rarely aware of these. React to tension, stretching, rate of muscle contraction. Essential for coordination of muscular action. Provide sensory feedback for muscles. OCTAVOLATERALIS SYSTEM Lateral line system Ear } connected Both with receptor hair cells. From adjacent neurogenic?? placode Innervation adjacent: VIII + Lateral Line Nerves (unnumbered cranial nerves) have adjacent connection to medulla. OCTAVOLATERALIS SYSTEM Lateral Line System Mechanoreceptor organs arranged in a series of lines within skin. Anamniotes, including larval amphibians. Absent in all amniotes, including even fully aquatic forms. neuromast organ - OCTAVOLATERALIS SYSTEM Lateral Line System Neuromast Organ Arranged within protected canals in skin. Hair cell w/ long kinocilium and smaller stereocilia (15-30). hair cell OCTAVOLATERALIS SYSTEM Lateral Line System Neuromast Organ Arranged within protected canals in skin. Hair cell w/ long kinocilium and smaller stereocilia (15-30). Tonic receptors = base rate of neural impulses. Directional bending of cupula. toward kinocilium = increase rate away from kinocilium = decrease rate Thus can detect directional water movement. Likely brain deletes signal from fish’s own movement. “Distant touch” ELECTRORECEPTORS Water conducts electricity. Electroreception evolved multiple times in aquatic verts w/ variety of hair cells. Ampullary organs = Ampullae of Lorenzini. ‘ampulla’ = flask, so sac-like enlargement Passive electrolocation of prey. Navigation Swimming in earth’s magnetic field generates small voltage gradient. ELECTRORECEPTORS Active electrolocation Fish generate high frequency electric pulses + fields using modified muscles. Tuberous organs used for detection. EAR All vertebrates with inner ear. Tetrapods also with middle ear +/- external ear. Inner ears Bat-eared fox INNER EAR Invagination of ectodermal otic placode (otic vesicle). Otic vesicle differentiates into a series of sacs and ducts. Membranous labyrinth - filled with endolymph within Cartilagenous labyrinth (e.g. shark) - with perilymph outside of mem. lab. or Osseous (bony) labyrinth INNER EAR Semicircular ducts (within canals) Hagfish w/ 1 Lamprey w/ 2 (and fossil ostracoderms) Gnathostomes w/ 3, oriented ⏊ to each other. 1 2 3 3 INNER EAR Semicircular ducts (within canals) Hagfish w/ 1 Lamprey w/ 2 Gnathostomes w/ 3, oriented ⏊ to each other. Connect at utriculus and to sacculus Each duct with ampulla with patch of hair cells, crista. Utriculus & sacculus Large patch of hair cells, macula. Maculae overlain by otolith or many otoconia (dogfish uses sand grains!). Otolith & otoconia high density calcareous structures. INNER EAR Equilibrium Hair cells in ampullae, utriculus, sacculus detect changes in position and movement via fluid inertia/movement in ducts. Static Equilibrium Gravity’s pull on otolith or otoconia. Shift of these structures over hair cells. Inertia/differences in density….w/ acceleration, otolith lags behind.  santanae is relatively largeplane in comparison to similarly of the lateral sizedto canals) reptiles, operate but with does not fall within optimal perhaps sensitivity13 or not to the extent observed here. 28 the range canalsof(Fig. extant2), birds. perhaps Data for taxa evenother thanallowing the pterosaurs for a derive from Hurlbertview; and greater INNER EAR he semicircular rtially knownseeforMethods for details and one pterosaur, equations. overlap simply less obstructed of the visual fields (binocular vision; Fig. 4e). Differences The great enlargement of the flocculus in pterosaurs, on the other in hand, although reported previously2,5, has not been widely s labyrinth is preserved bilater- head orientation may correlate with differences in bodyappreciated. posture Lateral semicircular duct typically held horizontally. majority of it is preserved in during terrestrial quadrupedal locomotion in that Rhamphor- ular canal system is greatly hynchus, with its relatively shorter forelimbs, must have adopted a In extant nonavian reptiles, the flocculus is incon- spicuous, whereas in birds and many other dinosaurs, the flocculus Has been used to reconstruct postures and head positions of extinct animals. namic effects of a declined versus a perhaps more streamlined is larger and housed in a small bony recess. In Rhamphorhynchus ircling the flocculus. Its general more horizontal trunk, whereas Anhanguera had longer forelimbs of birds andhorizontal head orientation some other dino- and so had have a morenot been body upright fullyposture assessed, 6,18,19 but and Anhanguera, however, the flocculus is larger than the optic , which in turn e.g. , pterosaurs. 18 y modest in merit consideration these groups, the required , particularly given down-turning a compensatory the great length of theof theThetectum, head. aerody- forming a prominent lobe projecting from the caudolateral skull of Anhanguera and the fact that the bill bears a crest. It is worth corner of the cerebellum (Fig. 2). The virtual endocasts allow noting that the occiput bears an extensive and robust attachment quantification of relative floccular size. In Rhamphorhynchus and surface for neck musculature, and the cervical vertebrae are simi- Anhanguera, the flocculi occupy about 7.5% of total brain mass, larly stout (Fig. 1e–f). Thus, the head and neck appear to have been whereas in birds their relative mass is much less (1–2%). No well-adapted to resist the large sagittal bending moments induced other vertebrate group has so expanded the flocculus. In fact, by aerodynamic forces in the declined head posture model (Fig. 4c). the enlarged semicircular canals could be an epiphenomenon of Rhamphorhynchus, by comparison, appears to have had only primary floccular enlargement in that the canals are apparently Figure 2 Endocasts and labyrinths of pterosaurs compared to brains of extant archosaurs. the raw slice data. Some details of the ventral portion of the virtu a, Brain of the crocodilian archosaur Alligator mississippiensis in right lateral view. Rhamphorhynchus were not well enough preserved to allow unequ b, Brain of the avian archosaur Columba livia (pigeon) in right lateral view. c–e, Endocast a and b modified from originals29,30. Scale bars equal 10 mm. AnC and osseous labyrinth of Rhamphorhynchus muensteri in right lateral (c), dorsal (d), and canal; Cbl, cerebellum; CC, crus communis; Cer, cerebrum; CN II ventral (e) views. f–h, Same of Anhanguera santanae in right lateral (f), dorsal (g), and nerve); CN III, cranial nerve III (oculomotor nerve); CN V, cranial nerv ventral (h) views. Major areas of the brain are labelled for the alligator and pigeon, and the Flo, flocculus (cerebellar auricle); LaC, lateral (horizontal) semicircu corresponding regions of the endocasts are given the same colour. The lagenar (cochlear) (cochlea); Med, Medulla; Olf, olfactory lobe (bulb); Op, optic lobe (t regions of both pterosaurs and some parts of the lateral semicircular canal of semicircular canal. Rhamphorhynchus were not included in the virtual endocasts but were reconstructed from NATURE | VOL 425 | 30 OCTOBER 2003 | www.nature.com/nature © 2003 Nature Publishing Group s compared to brains of extant archosaurs. the raw slice data. Some details of the ventral portion of the virtual endocast of mississippiensis in right lateral view. Rhamphorhynchus were not well enough preserved to allow unequivocal reconstruction. igeon) in right lateral view. c–e, Endocast a and b modified from originals29,30. Scale bars equal 10 mm. AnC, anterior semicircular uensteri in right lateral (c), dorsal (d), and canal; Cbl, cerebellum; CC, crus communis; Cer, cerebrum; CN II, cranial nerve II (optic antanae in right lateral (f), dorsal (g), and nerve); CN III, cranial nerve III (oculomotor nerve); CN V, cranial nerve V (trigeminal nerve); belled for the alligator and pigeon, and the Flo, flocculus (cerebellar auricle); LaC, lateral (horizontal) semicircular canal; Lag, lagena en the same colour. The lagenar (cochlear) (cochlea); Med, Medulla; Olf, olfactory lobe (bulb); Op, optic lobe (tectum); PoC, posterior he lateral semicircular canal of semicircular canal. ual endocasts but were reconstructed from ture.com/nature © 2003 Nature Publishing Group 951 OCTAVOLATERALIS SYSTEM Lateral line system Ear } connected Both with receptor hair cells. From adjacent neurogenic?? placode Innervation adjacent: VIII + Lateral Line Nerves (unnumbered cranial nerves) have adjacent connection to medulla. HEARING displacement v pressure waves Sound waves with two components in water and air:  TETRAPODS * 2 sets of limbs with feet and girdles. * 1 sacral vertebra for pelvis. * Mobile neck. “Fish” vs Tetrapods HEARING Hair cells are Sound waves with two components in water and air: mechanoreceptors, 1. Displacement waves need displacement waves. Particle motion - analogous to ripples in water. Low frequency. Decays very rapidly, ‘near-field’. Dominant close to source. 2. Pressure waves Compression and rarefaction of molecules. Slow decay & frequency dependent. Important at distant, ‘far-field’. HEARING - Aquatic Environments Fish 1. Near field Displacement affects hair cells as well as lateral line. Passes through skin and tissue. Movement of otolith lags behind rest of tissue. HEARING - Aquatic Environments Fish 2. Far field More complex. Fish with similar density to water; “transparent” to sound pressure waves. Some fish use gas bladder. Gas with much lower density, vibrates at frequency of pressure wave. Webbarian ossicles (apparatus) Series of bony elements connects bladder to sacculus. Analogous to tympanic membrane (ear drum) and ear ossicles. Ostariophysans (carps, minnows, etc.)  In some fish, anterior extensions fo swim bladder contact inner ear. Ostereophysans with elaborate Webbarian apparatus. HEARING - Aquatic Environments Fish 1. Near field (Displacement waves) Displacement affects hair cells as well as lateral line. Passes through skin and tissue. Movement of otolith lags behind rest of tissue. 2. Far field (Pressure waves) More complex. Fish with similar density to water; “transparent” to sound pressure waves. Some fish use gas bladder. Gas with much lower density, vibrates at frequency of pressure wave. Webbarian ossicles (apparatus) Series of bony elements connects bladder to sacculus. Analogous to tympanic membrane and ear ossicles. Ostariophysans (carps, minnows, etc. In some fish, anterior extensions fo swim bladder contact inner ear. HEARING on land….. Tetrapods Low frequency sounds with enough intensity Can generate displacement waves strong enough to displace skull bones. Some verts (caecilians, salamanders, snakes) detect low-freq. sounds this way. HEARING on land….. Tetrapods High frequency sounds With air’s low density, only operate as pressure waves. Must be amplified in order to produce displacement in fluid-filled spaces of inner ear. (Webbarian apparatus/swim bladder analogous). Hair cells are mechanoreceptors, need displacement waves. HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 1.Tympanic Membrane Evolved 3 times within tetrapods - frogs, reptiles, mammals. HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 1.Tympanic Membrane Evolved 3 times within tetrapods - frogs, reptiles, mammals. 2.Middle Ear Air-filled space Connected by eustachian tube to pharynx (pouch #1). HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 3. Auditory Ossicle(s) Columella (amphibians, reptiles) or stapes (Mammals) cross middle ear. Homologous to hyomandibular of fish. oval window HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 3. Auditory Ossicle(s) Columella (amphibians, reptiles) or stapes (Mammals) cross middle ear. Homologous to hyomandibular of fish. Large tympanic plate vs. small foot plate (oval window) of inner ear Energy concentrated Pressure amplification Overcomes greater density (inertia, a.k.a. impedance) of perilymph. “impedance matching” oval window HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 4. Perilymphatic duct Carries displacement waves past receptor. Has mechanism to dissipate energy. e.g. May loop back to middle ear cavity at round window. perilymphatic duct perilymphatic duct HEARING on land….. Tetrapods Features convert pressure waves to displacement waves: 4. Perilymphatic duct Carries displacement waves past receptor. Has mechanism to dissipate energy. e.g. May loop back to middle ear cavity at round window. 5. Sensory system Within membranous labyrinth. Specialized hair cells within structure (cochlea or cochlear duct). perilymphatic duct perilymphatic duct HEARING on land….. Tetrapods - Ear Specializations auricular operculum Lissamphibia (Amphibians): Operculum - additional auditory ossicle. - in oval window and connects to foot plate. HEARING on land….. Tetrapods - Ear Specializations Lissamphibia (Amphibians): Operculum - additional auditory ossicle. - in oval window and connects to foot plate. Opercularis muscle From operculum to pectoral girdle. Connects inner ear to girdle, leg, & ground. Mechanism for detecting low-frequency ground vibrations. HEARING on land….. Tetrapods - Ear Specializations Snakes & some lizards: Columella connects to quadrate. Largely restricts hearing to ground vibrations thru lower jaw. HEARING on land….. Tetrapods - Ear Specializations Birds: Cochlear duct. Asymmetry in some ears helps locate sound source. HEARING on land….. Tetrapods - Ear Specializations Mammals External ear - Auricle (pinna) to amplify and concentrate sounds. Bat-eared fox Long-eared jerboa HEARING on land….. Tetrapods - Ear Specializations Mammals External ear - Auricle (pinna) to amplify and concentrate sounds. Three ear ossicles. Incus, malleus = modified quadrate + articular. Serve as lever system to further amplify sound but reduces total movement.  Bird, lizard Mammal Anatomy of the middle ear. (a) Schematic of a sauropsid (bird, lizard) middle ear with a single ossicle spanning the middle ear cavity. (b) Schematic of a mammalian middle ear with three ossicles in a chain within the cavity. Origin of ossicles: Light blue denotes first arch neural crest derived tissue. Dark blue denotes second arch neural crest derived tissue. Red denotes mesoderm-derived tissue (stapes footplate). S, stapes; M, malleus; I, incus; MEC, middle ear cavity. HEARING on land….. Tetrapods - Ear Specializations Mammals External ear - Auricle (pinna) to amplify and concentrate sounds. Three ear ossicles. Incus, malleus = modified quadrate + articular. Serve as lever system to further amplify sound but reduces total movement. Total amplification Force on footplate 22x that on tympanum. But only 1/3rd the movement. HEARING on land….. Tetrapods - Ear Specializations Mammals Tensor tympani and stapedius Muscles attached to ossicles + dampen sounds (e.g., own voice). HEARING on land….. Tetrapods - Ear Specializations Mammals Tensor tympani and stapedius Muscles attache to ossicles + dampen sounds (e.g., own voice). Cochlea - snail-like coiled structure of perilymphatic duct. Platypus has only quarter turn. Humans with 3.5 turns. Guinea pig with 4 turns. Scala vestibuli/heliocotrema and Scala tympani around cochlear duct. Dissipate energy by connecting to round window (fenestra cochlea). OCTAVOLATERALIS SYSTEM Lateral line system Ear } connected Both with hair cells. From adjacent neurogenic?? placode Innervation adjacent: VIII + Lateral Line Nerves (unnumbered cranial nerves) have adjacent connection to medulla.