Mechanoreceptors Flashcards
What are receptors?
nerve/epithelial tissue responding to stimuli by developing action potentials
What are primary and secondary receptor cells?
primary receptor cells are specialized neurons and secondary cells are epithelial cells
What is a stimulus?
any environmental parameter causing a response in a nerve muscle or gland
What is a sensation?
perception or awareness of a stimulus received by sensory receptors
What are general senses?
senses that are superficial and deep afferent neurons that carry the signal from PNS to CNS such as on the skin surface
WHat are the special senses?
sensory modalities that are specialized that are designed to pick up a specific type of stimuli and often are hardwired into the brain as cranial nerves
What is one component that separates the special senses from the general senses?
The special senses normally have an accessory component or many accessary components associated with them- things that help to shape or filter the signal before it gets to the receptor
What are naked neurons?
Neurons that do not have a myelinated sheath.
What is sensory coding?
receptor sensitivity for each type of stimulus to elicit a unique different response
How do you recognize the difference between senses?
By where the sense ends up in the brain not bc of the receptor
What are the morphological considerations when referring to the different types of receptors?
- Filtering-to pick up different types
- Amplification-connect receptors so its additive to make signal stronger
change the receptors so they are specific to a certain type of information they can code for
What are three types of signal filtering?
- low pass filters-pick up low frequencies
- high pass filters-pick up high frequencies
- band pass filters-sensitive to a certain series of frequencies within a range
WHat do general mechanoreceptors respond to?
sheer or torque forces
What is the structure of general mechanoreceptors?
Undifferentiated neurons with few processes and naked neurons lacking myelin sheath.
What is the mode of mechanoreceptor stimulation?
direct distortion
WHat are the two different ways in which a signal can be coded?
- tonic receptors-receptor sends off a pulse continuously
2. phasic receptors-spiked
What are Meissner’s corpuscles sensitive to?
touch and pressure
What are free undifferentiated nerve endings sensitive to?
Nociception and we register it all as pain.
what are the two groups of nociceptors?
- fast response nociceptors-pick up sharp well localized type of pain ex:step on nail
- slow propagation nociceptors-sense of burning or achy pain and are very diffused ex:cold hurt everywhere
What and where are propriorecptors?
Found in the Pacinian corpuscles. Sense deep pressure within muscles/joints, can pick up vibrations and position or bending moment in joints.
And also help you to walk or run that you don’t think about transfer back to cerebellum.
What are the thermoreceptors?
receptors for temperature. Found on the surface of the skin and tongue. unmyelinated neurons.
What are the only receptors in the brain?
Thermoreceptors in the hypothalamus and also integrates temp info coming form the periphery of the skin.
What are infrared receptors in pit vipers and what do they actually sense?
Membrane in the pit organ is covered with specialized neurons that are sensitive to temperature. Infrared radiation comes in through an opening strikes the membrane and heats it up. A tiny change in temperature as little as .002 degrees is enough to send off an action potential to the brain that also forms images. Most sensitive receptor known.
Why do we see so many special sense cells with secondary sense cells (epithelial tissue) and nor primary sense cells (nerves)?
Secondary sense cells give a graded response and Primary sensory cells are nerves that give an all or none response.
What is the advantage of a graded response?
Gives a more sophisticated signal that can send more complex information.
What are hair cells?
special epithelial cell that is sensitive to sheer or torque forces
What is the structure of hair cells?
There is an apical surface that is exposed to the stimulus and a basal surface that synapses with the interneurons or motor neuron.
What are the cell processes on the apical portion of the hair cells? and how do they work?
- kinocilium-long process, was once a cillia or flagella and has 9+2 arrangement microtubules
- stereocilia- always shorter than kinocilia. not like cilia more like microvilli
polarity in cell from top to bottom and radial polarity
When you move the hair cells in various ways get different types of signals.
What is a statocyst?
A cavity that is fluid filled with patches of hair cells in the opening. A statolith is in the cavity and is more dense than the fluid or material the organism is in. In vertebrates this is called an end organ.
What is the function of the statocyst?
The fluid filled cavity id more dense than the fluid it is in causing the hair cells the hair cells to sink and in this way the organism can determine what is upright based on the gravity.
In fish what is the endorgan that is more dense than water called?
otolith
How can the endorgans be used to determine angular momentum and acceleration/
They must be modified and they are expanded into 3 semicircular canals that are at right angles to one another and each one in a different orientation in space. There are ampullae that are swellings that contain the hair cells. In the semicircular canals is fluid and the fluid moves the hair cells.
What is the gelatinous mass associated with the hair cells that moves with the movement of the fluid in the semicircular canals?
cupula and they act in unison as a waving flag and also creates a pressure and we can determine acceleration and angular momentum
static equilibrium
gravity
kinetic equilibrium
acceleration movement speed
What is and where is the naked neuromast found?
Found in fish and amphibians. It is made of hair cells and cupula that allows fish to use the lateral line system
What is the lateral line system?
Water movement across the neuromast stimulates the cupula and thus the hair cells and fish can pick up stimuli:
- current and direction and movement of water
- direction the fish swims through the water
- disturbances in the water flow across the body
EX: fish move in unison=schooling
