receptor

Examples of receptor in the following topics:

• Neurotransmitters

  • Neurotransmitters match up with receptors like a key in a lock.
  • A neurotransmitter binds to its receptor and will not bind to receptors for other neurotransmitters, making the binding a specific chemical event.
  • The cholinergic system has two types of receptors: the nicotinic receptor and the acetylcholine receptor, which is known as the muscarinic receptor.
  • Both of these receptors are named for chemicals that interact with the receptor in addition to the neurotransmitter acetylcholine.
  • However, they cannot bind to each others' receptors.

• Somatosensation: Pressure, Temperature, and Pain

  • Functionally, nociceptors are specialized, high-threshold mechanoceptors or polymodal receptors.
  • Proprioceptors are the receptor cells found in the body's muscles and joints.
  • Muscle receptors are most active in large joints such as the hip and knee joints, while joint and skin receptors are more meaningful to finger and toe joints.
  • Mechanoreceptors can be free receptors or encapsulated.
  • Examples of free receptors are the hair receptors at the roots of hairs, while encapsulated receptors are the Pacinian corpuscles and the receptors in the glabrous (hairless) skin: Meissner's corpuscles, Ruffini's corpuscles, and Merkel's discs.

• Gustation: Taste Buds and Taste

  • The salt receptor, NaCl, is arguable the simplest of all the receptors found in the mouth.
  • There are three different receptor proteins at work in a sour taste.
  • This involvement with sodium ions implies a relationship between salty and sour tastes receptors.
  • Umami is the newest receptor to be recognized by western scientists in the family of basic tastes.
  • It is thought that umami receptors act similarly to bitter and sweet receptors (involving GPCRs), but very little is known about their actual function.

• Introduction to Sensation

  • Sensation involves the relay of information from sensory receptors to the brain and enables a person to experience the world around them.
  • These sensory receptors include the eyes, ears, mouth, nose, hands, and feet (and the skin as a whole).
  • Rod and cone receptors in the retina of the eye perceive light; cilia in the ear perceive sound; chemical receptors in the nasal cavities and mouth perceive smell and taste; and muscle spindles, as well as pressure, vibration, heat and pain receptors in the skin, perceive the many sensations of touch.
  • Specialized cells in the sensory receptors convert the incoming energy (e.g., light) into neural impulses.
  • Explain how the brain and sensory receptors work together in the process of sensation

• Olfaction: The Nasal Cavity and Smell

  • Each of the 350 receptor types is characteristic of only one odorant type.
  • Each functions using cilia, small hair-like projections that contain olfactory receptor proteins.
  • Olfactory transduction is a series of events in which odor molecules are detected by olfactory receptors.
  • In mammals, olfactory receptors have been shown to signal via G protein.
  • This is a similar type of signaling of other known G protein-coupled receptors (GPCR).

• Mechanics of the Action Potential

  • G-protein coupled receptors: receptors that sense molecules outside the cell and thereby activate signals within it.
  • Ligand-gated ion channels: receptors that are opened or closed in response to the binding of a chemical messenger.
  • The binding of neurotransmitter causes the receptor molecule to be activated in some way.
  • Due to thermal shaking, neurotransmitter molecules eventually break loose from the receptors and drift away.
  • Electrical synapses are faster than chemical synapses because the receptors do not need to recognize chemical messengers.

• Stages of the Action Potential

  • Neural impulses from sensory receptors are sent to the brain and spinal cord for processing.
  • A neuron affects other neurons by releasing a neurotransmitter that binds to chemical receptors.
  • The effect upon the postsynaptic (receiving) neuron is determined not by the presynaptic (sending) neuron or by the neurotransmitter itself, but by the type of receptor that is activated.
  • A neurotransmitter can be thought of as a key, and a receptor as a lock: the key unlocks a certain response in the postsynaptic neuron, communicating a particular signal.
  • This is in contrast to receptor potentials, whose amplitudes are dependent on the intensity of a stimulus.

• Stimulants

  • Others block the action of certain receptors (such as the adenosine receptors) in a process known as receptor antagonism.
  • Still others cause action in other receptors (such as nicotinic acetylcholine) in a process known as receptor agonism.

• Other Steps

  • Long-term potentiation initiates NMDA (N-methyl-D-aspartate) receptors, which in turn influence the flow of information between neurons.
  • Two conditions must be present for NMDA receptors to activate - (1) glutamate needs to be released and bound to the NMDA receptor site, and (2) excitation must take place in postsynaptic neurons.

• Sensory Adaptation

  • When you rest your hands on a table or put clothes on your body, at first the touch receptors will recognize that they are being activated and you will feel the sensation of touching an object.
  • However, after sustained exposure, the sensory receptors will no longer activate as strongly and you will no longer be aware that you are touching something.