Receptors Flashcards
What is a Receptor?
Receptors are cells that detect a stimuli (change in environment)
What specific stimulus does the Pacinian corpuscle respond to?
-To pressure changes
What does the Pacinian corpuscle consist of?
-A sensory neuron, wrapped with layers of tissue separated by gel, the sensory neuron has specialized channel proteins in its plasma membrane
Stretch Mediated Channel Proteins
-Pressure has to be applied for these sodium channels to be opened, the neuron plasma membrane is deformed and the channel proteins are stretched, that means more sodium ions diffuse back in and this establishes a generator
Where is the Pacinian corpuscle found?
-Deep in skin
-Mostly fingers and toes
Rods and Cone Location
-The retina
Rod Cells Function
-Rod cells process images in black and white, to create an action potential, light intensity is absorbed and a pigment called Rhodopsin, enough must be broken down to reach the threshold in the bipolar cells (in which they are attached to)
What is Retinal Convergence?
- There is many Rod cells connected to one bipolar cell, which are connected to sensory neuron, this means low light intensity is required because collectively, there is enough breakdown to trigger and action potential
-This is called summation.
Advantages/Disadvantages to Retinal convergence
-Still be able to see in black and white at low light intensities.
-Low visual acuity (quality of vision) - Not very accurate vision in low light intensities, brain cannot distinguish between different light sources
What are the 3 different types of Cone cells?
-different iodopsin pigment, one red, one green the other is blue, all absorb different wavelengths of lights, depending on proportion of red, green and blue stimulated, we perceive a whole range of different colors
what is Iodopsin?
-Iodopsin is a photochemical pigment, contained within cone cells in the retina
-It requires a high light intensity to be broken down
-it consists of RETINOL and a protein
-different colours
Why can’t we see color in the dark?
-Not enough light energy to break down iodopsin and generate an action potential
-There is no retinal convergence and therefore no spacial summation
What is the distribution of rod and cone cells like within the eye.
-Cone cells at the highest at the fovea, which will constantly receive the higher light intensities
-Rod cells further away, respond to lower light intensities
What does myogenic mean?
Myogenic means that the heart muscle can relax and contract without receiving a signal from any nerves. The patterns of contractions control a regular heart beat
What is the SANs role ?
-The SAN generates an electrical impulse and sends this impulse to the walls of the atrium (right atrium)
-Regulates heartbeat and acts as a pacemaker
