Sense organs

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Sense organs
2014-04-29 19:31:00
sense organs biology science
science,biology,sense organs
Sense organs in Gen bio
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  1. Sensory transduction
    conversion of a physical or chemical stimulus to a change in the membrane potential of a sensory receptor
  2. Receptor potential
    the change in membrane potential of the sensory receptor it self is called
  3. Transmission
    • the information is gathered through summation on the neuron
    • neurons that only function as sensory neurons have their axons in the CNS 
    • non-neuronal neurons stimulate the amount of AP of an afferent neuron or how much hormone the neuron will secrete 
    • the stronger the stimuli the more APs will happen
  4. Perception
    • taste, smell, sound, sight and touch
    • the brain can distinguish between these stimuli because each uses a different neuron pathway to reach a different part of the brain
  5. Amplification and adaptation
    • amplification uses secondary messengers 
    • takes place in accessory organs 
    • sensory adaptation
  6. Types of receptors
    • mechanoreceptors
    • thermoreceptors
    • pain receptors
    • chemoreceptors 
    • electromagnetic receptors
  7. Mechanoreceptors
    • sense touch, pressure, stretching, motion and sound PHYSICAL DEFORMATION
    • responsible for hearing and equilirbrium
    • bending or stretching o the cilia causes depolarization of the neurons resulting in the transmission of the information
    • touch=mechanoreceptors that are dendrites, these are usually in connective tissue
  8. Chemoreceptors
    • transmit information about solute concentrations and the concentrations of individudal molecules 
    • osmoreceptors
  9. Osmoreceptors
    • a type of chemoreceptor
    • detects total concentration of blood, and stimulates thirst
  10. Electromagnetic receptors
    • detect light, electricity and magnetism
    • allows some animals like whales to migrate using the earths magnetic waves as a compass, also allows other animals to detect prey
  11. Thermoreceptors
    • detect heat and cold
    • located in the skin
    • the bodies thermostat is the hypothalamus
    • mammals have many thermoreceptors for each specific temperature
    • uses TRP
  12. Pain receptors
    • also called nociceptors 
    • pain is amplified by the hormones in the body, like prostalglandins
  13. Mechanoreceptors help in
    • hearing and equilibrium
    • invertebrates= the mechanoreceptors are in the organ called STATOCYSTS. inside the organ, there are STATOLITHS and depending on which way the head is turned will move the statoliths until they settle a certain way, triggering the neurons 
    • insects= most have hairs the outside the body that respond to sound waves
  14. The EAR
    • outer ear
    • middle ear
    • inner ear
  15. Outer ear
    pinna, auditory canal;these collect the sound waves and take them to the tympanic membrane (eardrum)
  16. Middle ear
    stapes, malleus, incus, tympanic membrane, oval window; the stapes covers the oval window, which turns the sound waves to fluid waves
  17. Inner ear
    • cochlea=contains the organ of corti
    • semicircular canals=functions in equilibrium 
    • round window= dissipates the sound waves so you dont continue hearing the same sound forever
    • auditory nerve
  18. The organ of corti
    • Where fluid waves are sent to the brain
    • Structure: tectorial membrane, basilar membrane, hair cells, vestibular canal, tympanic canal which are separated by the cochlear canal
  19. Function of the organ of corti
    • the waves make the basilar membrane (the floor of the corti) shake
    • when it vibrates, the hairs attached (mechanoreceptors) to the basilar and tectorial membrane, bend
    • causing the tectorial membrane to shake
    • this causes the hair cells to depolarize sending the info to the brain
  20. The pathway of hearing
    • 1. pinna
    • 2. auditory canal
    • 3. tympanic membrane
    • 4. malleus, incus, stapes
    • 5. oval window
    • 6. coclea 
    • 7. round window
  21. Equilibrium
    • The semicircular canals 
    • utricle and saccule 
    • the canals have hair projections that are encapsulated in a capula which contains otoliths that press agaisnt the hairs when we turn our heads
    • also when we turn out heads, the perilymph, presses agaisnt the capula causing the hairs to depolarize
  22. The basilar membrane
    • not continuous all through,
    • has sections that are thin and thick each section corresponds to a different pitch, and sends it to the brain
  23. Hearing in fishes
    • use the lateral line system
    • do not have coclea, eardrum, or an opening
    • have inner ears and otoliths 
    • the lateral line system covers thier sides, and when water pushes through it causes the capula to push on the hair cells causing them to depolarize
  24. Simple EYEs
    • planarians have eyespots (which contain photoreceptors) that detect light 
    • depending on the number of APs from both eyes the planarian can tell which way the light source is coming from and move in the opposite direction
  25. Compound Eyes
    • use light detectors called ommatidia 
    • each ommatidia has a lens that only focuses on a part of the visual feild
    • they are very good at detecting movement
  26. Single lens EYE structure
    • 0. Conjuctiva- mucous membrane 
    • 1. Sclera- connective tissue 
    • 2. Cornea- part of the sclera 
    • 3. aqueous humor
    • 4. pupil
    • 5. iris- regulates amt of light coming in through the pupil, also formed from the choroid
    • 6. lens
    • 7. Suspensory ligament
    • 8. choriod- pigmented layer 
    • 9. retina
    • 10. virteous humor
    • 11. fovea- ONLY CONES HERE
    • 12. optic disk- no rods and cones (blind spot)
    • 13. optic nerve
  27. The retina
    • rods and cones- photo receptors; cones=color, rods=light and dark
    • bipolar cells- receives info from rods and cones
    • ganglion- gathers the input from the bipolar cells 
    • horizontal and amacrine cells- integrate info across the retina
  28. The visual pigments
    • the light abosorbing molecule retinal is bound to membrane membrane opsin
    • **when light hits the retinal it shifts form cis to trans, this change is what activates opsin
    • rhodopsin are only in rods
  29. Sensory transduction in the EYE
    • 1. light converts retinal from cis to trans, activating rhodopsin
    • 2. rhodopsin activates G protein transducin
    • 3. transducin activates phosphodisterase
    • 4. phosphodisterase truns cGMP to GMP
    • 5. sodium channels close, the rod hyperpolarizes
  30. Optic nerves
    • formed by the axons of ganglion cells
    • they meet at the optic chiasm
    • pictures from the right eye go to the left side of the brain and vice versa
  31. Lateral inhibition
    horizontal cells inhibit other distant photoreceptors from activating, meaning that the only area lit will be well focused, sharper image
  32. In the Dark, RODS and CONES...
    • depolarized and releasing glutamate
    • this can cause either the depolarization or hyperpolarization of bipolar cells
  33. When Light strikes the RODS and CONES...
    • they stop releasing glutamate
    • and the bipolar cells that were depolarized hyperpolarize, and the ones that were hyperpolarized, depolarize
  34. Colors in mammals
    • based on three types of cones, each has either red, blue, green pigment
    • called photopsins 

  35. Focusing in the mammalian eye
    • ciliary muscles contract, causing the lens to thicken, allowing the person to see nearby objects
    • ciliary muscles relax, causing the lens to thin, allowing the person to see far objects 
  36. Taste in Mammals
    • gustation= taste
    • taste buds located on papilla that each have the 5 sensory receptors (sweet, sour, bitter, salty, umami)
    • the receptors belong to the TRP family
  37. Smell
    • olfaction= smell
    • odorants= smell particles in the air
    • the odorants bind to chemoreceptor proteins in the plasma membrane of the hair cellls (olfactory receptors) and if they fit, they depolarize sending information to the olfactory bulb