Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
General and Special Senses Ch. 49 AP Biology Ms. Haut Classification of Sensory System by structural Complexity General Senses – Nocioreceptors – Thermoreceptors – Mechanoreceptors – Chemoreceptors Special Senses – Olfaction – Vision – Hearing – Taste – Equilibrium Sensory Receptors Gather information and pass it on to the CNS. Specialized cells or cell processes monitoring conditions in/outside body Specific for a certain type of stimulus → “receptor specificity” Sensory Transduction Sensory transduction – Conversion by sensory receptors of stimuli into electrical signals. Receptor potentials – Changes in membrane potentials caused by sensory stimuli. – Vary in intensity, depending on the strength of the stimulus. Receptor potential transmitted to CNS Sensory Integration Receptor potentials are integrated through summation In sensory adaptation, – Some sensory receptors become less sensitive when they are stimulated repeatedly. – Make wearing clothing uncomfortable without it Complexity Range of Receptors Free nerve ending Encapsulated nerve ending Specialized receptor cells Types of Sensory Receptors Mechanoreceptors Chemoreceptors Electromagnetic receptors Thermoreceptors Nocioreceptors (pain receptors) Sensory Receptors – A section of human skin Reveals why the surface of our body is sensitive to such a variety of stimuli. Mechanoreceptors Respond to physical distortion of cell membrane (pressure, touch, stretch, motion, and sound) – Baroreceptors Sensitive to internal pressures: blood pressure, lung stretch, digestive tract tension – Proprioceptors monitors of muscle stretch – Tactile receptors - touch, pressure, vibration Unencapsulated: free nerve endings, Merkels dics fine touch Encapsulated: Meissners corpuscles - fine touch; Pacinian corpuscles - deep pressure Chemoreceptors Respond to small concentration changes of specific molecules (chemicals) Internal chemoreceptors monitor blood composition (e.g. Na+, pH, pCO2 ) Found within aortic and carotid bodies Very important for homeostasis http://ecc-book.com/assets/images/carotid_and_aortic_bodies.jpg Electromagnetic Receptors Detect various forms of electromagnetic energy (visible light, electricity, magnetism) Photoreceptors—detect visible light Snakes have infrared receptors—detect body heat Some fishes use electroreceptors—locate objects and prey Birds, salmon, sea turtles use Earth’s magnetic field for migration Thermoreceptors Respond to changes in temperature In dermis, skeletal muscles, liver and hypothalamus Free nerve endings – Cold receptors – Warm receptors http://lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alecture/alect_stud/ach18_s.ppt . Respond to heat, mechanical stress and chemicals associated with tissue damage – Most concentrated in skin – Function is protection against further tissue damage – Generally do not adapt to continual stimuli. Visceral Pain: – Only visceral receptors that produce sensations; – Stretch receptors are stimulated by pressure and/or a decrease in oxygen levels – May feel as if its coming from another area of the body = referred pain. http://lpc1.clpccd.cc.ca.us/lpc/zingg/ana t/alecture/alect_stud/ach18_s.ppt. Nocioreceptors (Pain Receptors) http://lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alecture/alect_stud /ach18_s.ppt. Pain Management Prostaglandins increase pain by sensitizing receptors Aspirin and Ibuprofin reduce pain by inhibiting prostaglandin synthesis Special Senses Hearing Equilibrium Vision Olfaction Taste Hearing The ear is composed of three regions: – The outer ear, the middle ear, and the inner ear Ear Structure and Function http://www.lhsc.on.ca/cochlear/images/sound2.jpg The outer ear – Consists of the pinna and the auditory canal. – Collects sound waves and passes them to the eardrum, a sheet of tissue that separates the outer ear from the middle ear. Ear Structure and Function http://www.hawkeyecollege.edu/faculty/cdostal/A&P%20Powerpoints/Spec ial%20Senses.ppt#287,34,Slide 34 When sound waves strike the eardrum, – It vibrates and passes the sound waves to three small bones. Ear Structure and Function http://www.hawkeyecollege.edu/faculty/cdostal/A&P%2 0Powerpoints/Special%20Senses.ppt#287,34,Slide 34 The inner ear – Consists of fluid-filled channels in the bones of the skull. http://lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alecture/alect_stud/ac h18_s.ppt. Semicircular canals— equilibrium Cochlea—hearing Organ of Corti Actual hearing organ – Is found within the cochlea. – Consists of hair cells, the receptor cells of the ear. Hearing When sound waves are collected by the outer ear, – They are transmitted eventually to the cochlea. – Hair cells in the organ of Corti bend, which triggers nerve cells to send signals to the brain. Auditory Pathway Cochlear branch of CN VIII To inferior colliculus of opposite side of midbrain To cochlear nucleus of medulla To thalamus To auditory cortex Louder sounds – Cause greater movement of the hair cells and more action potentials. http://www.hawkeyecollege.edu/faculty/cdostal/A&P%20Powerpoints/Special%20Senses.ppt#287,34,Slide 34 Hearing Problems Deafness, the loss of hearing, can be caused by infections, injury, or overexposure to loud noises. – Conduction hearing loss – Sensorineurial hearing loss Conduction Hearing Loss Caused by anything that interferes with the transmission of sound from the outer to the inner ear. – Middle ear infections (otitis media). – Blockage of the outer ear, most commonly by wax. – Otosclerosis—ossicles of the middle ear harden and become less mobile. – Damage to the ossicles, for example by serious infection or head injury. – Perforated eardrum, caused by an untreated ear infection, head injury or a blow to the ear, or from poking something in your ear. Information from: http://www.deafness-and-hearingaids.net/2007/10/25/conductive-and-sensorineural-hearing-loss/ Sensorineural Hearing Loss Due to damage to the pathway that sound impulses take from the hair cells of the inner ear to the auditory nerve and the brain. – Age-related hearing loss (presbyacusis). It’s partly due to the loss of hair cells in the cochlea. – Acoustic trauma (injury caused by loud noise) can damage hair cells. – Certain viral or bacterial infections such as mumps or meningitis – Certain drugs, such as some powerful antibiotics, can cause permanent hearing loss. – Acoustic neuroma. This is a benign tumor affecting the auditory nerve. It needs to be observed and is sometimes treated with surgery. – Other neurological (affecting the brain or nervous system) conditions such as multiple sclerosis, stroke, or a brain tumor. Information from: http://www.deafness-and-hearingaids.net/2007/10/25/conductive-and-sensorineural-hearing-loss/ Organs of Equilibrium Receptor cells are in two structures Vestibule Semicircular canals Figure 8.16a, b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Organs of Equilibrium Equilibrium has two functional parts Static equilibrium – sense of gravity at rest Dynamic equilibrium – angular and rotary head movements Figure 8.16a, b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Equilibrium http://www.mnstate.edu/rodenb/Human%20Biology/senses%20lec%20handout.pdf Inner ear detects the position of the body with respect to gravity and the motion of the body. Vision http://209.132.69.82/zbc_uploads/user_image1038344076qxg.jpg – The human eyes Are able to detect a multitude of visual stimuli. Structure of the Human Eye Function of the Structures Sclera – Is the outer covering. Cornea – Lets light into the eye and also helps focus light. Function of the Structures Iris – Regulates the size of the pupil, which lets light into the interior of the eye. Lens – Focuses light onto the retina by refracting light rays and changing shape. Function of the Structures Two fluid-filled chambers make up the bulk of the eye. – The large chamber is filled with vitreous humor. – The small chamber contains aqueous humor. Accomodation Accomplished by changing the curvature of the lens – For distant objects, the lens needs to be made flatter – For near objects the lens needs to be made thicker and more rounded Seeing in Color Built into the human retina – Are two types of photoreceptors named for their shapes. http://www.hawkeyecollege.edu/faculty/cdostal/A&P%20Powerpoints/Special%20Senses .ppt#269,14,Slide 14 Photoreceptors http://www.medgadget.com/archives/img/retinal_layers.jpg Cones – Are stimulated by bright light and can distinguish color. 3 types which distinguish red wavelengths, blue wavelengths, and green wavelengths – Contain visual pigments, photopsins, which absorb bright light. Photoreceptors Rods – Are extremely sensitive to light and enable us to see in dim light, though only in shades of gray. – Contain a visual pigment, rhodopsin, which can absorb dim light. Photoreceptors The fovea contains a high concentration of cones and is the retina’s center of focus. Rods are concentrated in the peripheral regions Visual Pathway Optic chiasma - optic nerves partially cross (right side of the field of each eye combining and going to the lateral geniculate on the right, those from the left to the left) Vision Problems and Corrections Three of the most common visual problems – Are nearsightedness, farsightedness, and astigmatism. – Result from focusing problems. – Can be helped by corrective lenses or surgical procedures. Nearsightedness (myopia) Occurs when the eyeball is longer than normal. Farsightedness (hyperopia) Occurs when the eyeball is shorter than normal. Blurred vision caused by a misshapen lens or cornea. Glasses and contacts can be used to correct problem http://www.optometrists.asn.au/freestyler/files/Astigmatism.gif Astigmatism Chemical Senses – Taste and Smell Both senses use chemoreceptors Stimulated by chemicals in solution Taste has four types of receptors Smell can differentiate a large range of chemicals Both senses complement each other and respond to many of the same stimuli Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Olfaction – The Sense of Smell Olfactory receptors are in the roof of the nasal cavity Neurons with long cilia Chemicals must be dissolved in mucus for detection Impulses are transmitted via the olfactory nerve Interpretation of smells is made in the cortex Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Olfaction – The Sense of Smell Olfactory Pathways Receptor neurons pass into cranium through cribiform plate and synapse in olfactory bulbs. Olfactory neurons are the only neurons known 1. to routinely replace themselves 2. to reach the cerebrum without synapsing in the thalamus Olfactory discrimination - Although difficult to describe, the number of different odors recognizable is immense. The Sense of Taste Taste buds house the receptor organs Location of taste buds Most are on the tongue Soft palate Cheeks Figure 8.18a, b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The Tongue and Taste The tongue is covered with projections called papillae Filiform papillae – sharp with no taste buds Fungifiorm papillae – rounded with taste buds Circumvallate papillae – large papillae with taste buds Taste buds are found on the sides of papillae Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Structure of Taste Buds Gustatory cells are the receptors – Have gustatory hairs (long microvilli) – Hairs are stimulated by chemicals dissolved in saliva http://www.lrn.org/Graphics/Senses/figure%208.8.gif Taste Sensations Sweet receptors Sugars Saccharine Some amino acids Sour receptors Acids Bitter receptors Alkaloids Salty receptors Metal ions Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 8.41 Gustatory Pathway Impulses are carried to the gustatory complex by several cranial nerves because taste buds are found in different areas – Facial nerve – Glossopharyngeal nerve – Vagus nerve