Lecture 18 - Sensory Systems 1

Question 1

How do sensory organs convey information to the CNS? (3)

Answer 1

A specialized receptor detects an environmental signal, the receptor triggers an action potential in a sensory neuron, the action potential in the sensory system ultimately relays a message to the central nervous system

Question 2

Thermoreception (2)

Answer 2

the ability to detect heat; pit vipers have temperature sensitive pits that detect infrared radiation from warm animals that allow pit vipers to strike prey accurately in complete darkness

Question 3

Electroreception (3)

Answer 3

The ability to detect electrical fields, sharks have specialized organs called Ampullae of Lorenzini that are used to hunt pray by detecting the electrical fields of other animals, some fish produce their own electrical fields and look for disruption in their electrical fields to notice and hunt prey

Question 4

Magnetoreception (4)

Answer 4

The ability to detect the magnetic field of the earth, sea turtles have this ability and use their magnetoreception to return to the same beach where they were hatched from, birds were found to have this ability as well and can navigate without seeing the sun, birds use magnetoreceptors as well as visual clues to navigate

Question 5

Mechanoreception (3)

Answer 5

Responding to distortion in pressure used for the detection for gravity as well as mechanical stress and hearing, when ear cells used to detect gravity are infected we get dizzy. A specialized receptor receives a specific signal from a stimulus such as the tympanic membrane vibrating and sends the sensory info to motor neurons

Question 6

Transduction (2)

Answer 6

The conversion of an external stimulus to an internal signal in the form of action potentials along sensory neurons, the rate that a sensory neuron fires depends on the frequency and loudness of a sound

Question 7

Mechanoreceptors in vertebrates (3)

Answer 7

Vertebrates detect pressure with hair cells with each cell having many stereocilia and a kinocilium (the longest projection), when the stereocilia are bent toward the kinocilium K+ ion channels are opened resulting in depolarization that triggers inflow of Ca2+ ions. Ca+ induces release of neurotransmitters across the synapse with neurotransmitters inducing an action potential in a sensory neuron

Question 8

Mechanoreceptors in vertebrates - mammals

Answer 8

In mammals sound waves vibrate the tympanic membrane and the vibrations are carried across the middle ear ones to the cochlea and through the cochlea they are carried in fluid to where they are detected by hair cells, the basilar membrane vibrates most at different points depending on the incoming frequency directly above regions where the basilar membrane is vibrating maximally hair cells will bend, therefore different hair cells are dedicated to detecting different sound frequencies