### body part:

Receptor
* All receptors transduce sensory input to a change in membrane potential.
* Most receptors detect conditions.
* Most receptors detect different conditions
  - external conditions
  - motion
  - pain
  - perceptible vibration
  - stimuli
* Most receptors respond to mechanical stimuli
* Some receptors are free nerve endings
  - glycoproteins, others are phospholipids or glycolipids
  - bind to effector proteins that generate a second messenger molecule
  - can move from the cytoplasm to the nucleus
  - control activities
  - detect presence
  - enhance phagocytosis
  - facilitate deliveries
* Some receptors have essential functions
  - specific functions
  - initiate killing, but other prevent killing
  - involve in phagocytosis
  - react to temperature while others react to pressure
* act as the gateway between nerve cells.
* activated by light provide different information about the magnetic field.
* also binds to immobilized rabbit actin or free neutrophil cytosolic actin.
* are an important part of the story of how viruses cause infection
  - another important control point for the effectiveness of synapses
  - cell components that combine with the hormone to alter the function of the cell
  - cells in the retina that perceive light
  - classified based on the source of the stimulus
  - down regulated during depression and immune system suppressed
  - in the cell membrane , with part of the receptor outside and part inside the cell
  - like letter boxes through which the enzyme can pass
  - molecules and structures that detect stimuli
* are molecules that allow cells to respond to chemical signals from other cells
  - receive messages from chemical messengers like dopamine
  - within brain cells that detect and respond to the vitamin
  - necessary to cellular signalling, adhesion, and recognition
  - nerve endings that have a chemical reaction to the food that is being eaten
* are present in most cells and it likely has many additional effects
  - on the cells in the human body just for the attachment of infectious agents
* are protein molecules that read and respond to hormone signals
  - tyrosine kinases
  - protein-based structures embedded in cell membranes which serve as relays for signals
* are proteins that serve as gatekeepers for the cell
  - typically sit on the surface of cells and bind molecules called ligands
  - responsible for filtering, transduction, amplification, and activation
  - sensitive to the rate of pressure change as well as to the steady or mean pressure
* are sites in and on brain cells that receive chemical messages
  - on cells that accept insulin and allow glucose to enter
  - small proteins that lie on the surface of a cell
  - specialized proteins that receive cellular signals
  - specific proteins that sit on the surface of cells and combine with substances
  - structures found on the surface of nerve cells
  - subject to up and down regulation
  - such mechanisms as the eye, ear, and taste buds
  - the place where drugs act
  - vital links in the body's command chain
* bind hormones with specificity, affinity and saturation.
* convert energy into electrical activity
  - environmental stimuli into neural impulses
* detect changes from the stable state
* determine which cells respond to a given growth factor.
* differ in the type of stimuli to which they respond.
* embedded in the membranes of cells are a. proteins.
* exist on cells that bind androgens.
* have different shapes, and thus interact with specific molecules
  - several properties
  - the ability to bind, internalize, and degrade thrombopoietin
* indicates the presence of members of the methyl-accepting chemotaxis protein family.
* is an organ
  - on adjacent cells
* mediate their actions by a cascade of enzymatic actions.
* mediated endocytosis is used by the cell to gather and being atoms.
* recognise response elements which are related to a consensus sequence.
* reduce their sensitivity if continuously stimulated.
* resemble locks into which only certain keys can fit.
* respond to chemical signals by starting or stopping particular activities within the cell
* share certain features with neurons.
* signalling major field of interest.
* stick out of the cell.
* usually are picky about what they allow to bind.