The Senses

What is an Energy Transducer?
An transducer is a device that converts a non-electrical signal into an electrical one.
The result is an action potential

ALL of your sensory receptors act as energy transducers…

You sense the world, and then send a signal to your brain to interpret it
The human sensory receptors are classified into groups…

Breaking up the Gang…
Chemoreceptors
Nasal cavity
Taste buds
Chemoreceptors have special proteins in their membranes. These proteins can bind to a particular substance and this will result in a depolarization of the membrane leading to an action potential being sent to the brain. Chemorecptors are responsible for our sense of smell and taste but also detect the blood pH.

Electroreceptors
Electrorecpetors are found, for example, in sharks. Muscle contractions generate electrical fields which are conducted by the water. The shark can sense these fields with is electroreceptors and detect its prey. As air is a poor conductor, terrestrial organisms would not have much use for this sense organ.

Mechanoreceptors
Cochlea
Inner Ear
another cool pic
Mechanoreceptors are those that are sensitive to some kind of movement. On fish, they are found in the 'lateral line system', which detects vibrations in the environment. We have a similar system in our inner ear to inform us of our body's position and movement. Three fluid filled semi circular canals are connected to the area. At the end of the canals, as well as in the common area, we find a system of hair cells. Any change in speed or direction will move the fluid in at least one of the semicircular canals, bending the hairs. This causes action potentials to be sent to the brain.

Thermoreceptor
Theremoreceptors are found, for example, in the skin. Cold receptors, just under the surface of the skin, will send an action potential when the temperature drops. Warm receptors, located a little deeper, will send an action potential when the temperature increases. the temperature centre in the hypothalamus of he brain also contains thermoreceptors to monitor the temperature of the blood.

Photoreceptor
Photoreceptors are the rods and cones in our eyes. Rods and cones cotnain photopigments that are broken down when exposed to light. This caues the cells to send an action potential to the brain.

Speaking of Photoreceptors…Why does it hurt your eyes when reading in the dark?
To answer that question,first let’s take a look at the structure of the eye

Take a look at this site for the eye pictures
Conjunctiva
Sclera
Cornea
Aqueous humour
Pupil
Iris
Ciliary Body
Suspensory Ligaments
Choroid
Optic Nerve
Lens
Vitreous Humour
Retina
Fovea

Blind spot
Draw an “X” and an “O” 5 inches apart on a piece of paper


How do we see?