4.36 Mechanoreceptors and Chemoreceptors – Flashcards

Conscious and subconscious awareness of changes in the external or internal environment.

Stimulation of the sensory receptor → transduction of the stimulus → generation of nerve impulses → integration of sensory input. 1. Stimulation of the sensory receptor. 2. Transduction of the stimulus. 3. Generation of nerve impulses. 4. Integration of sensory input.

these are nerve endings or specialised cells which convert stimuli from the external and internal environment into afferent nerve impulses which pass into the CNS

1- general senses : located throughout the body 2- special senses : all located in the head

" Widely distributed throughout the body and include touch, pressure,pain, temperature, vibration, itch ,and pro perception" 1- somatic 2- visceral * maintaining homeostasis

1- tactile (touch) 2- thermal (heat or cold) 3--pain 4- proprioceptive (joint position) sensations

provide information about conditions within internal organs.

1- smell (olfactory) 2- taste (gustatory) 3-vision (optic), 4-hearing (auditory) 5-equilibrium or balance (vestibular) * maintaining homeostasis

1- MECHANORECEPTORS 2- THERMORECEPTORS 3- NOCICEPTORS 4- PHOTORECEPTORS 5-CHEMORECEPTORS

detect mechanical deformation e.g. touch or pressure in the skin; stretch receptors in muscles. * mechanoreceptor cells respond to a change in the external stimulus (pressure, temperature, etc) by producing voltage pulses across neurons (i.e. generator potentials) .

detect changes in temperature

pain receptors stimulated by, for example, pinching, tearing or burning -are all free nerve endings;

detect light; the rods and cones of the retina

respond to chemical stimuli; e.g. taste, smell, changes in blood gases or pH.

1-Free nerve endings 2-Encapsulated nerve endings 3- Separate cells

in tissues that detect pain, temperature and light touch (Merkel's disc).

- consist of nerve endings surrounded by one or more layers of cells pacinian corpuscles. e.g. proprioceptors; Pacinian, Meissner's and Ruffini's corpuscles

* hair cells, photoreceptors and gustatory receptor cells , hair cells .

* Of all the receptors, the mechanoreceptors are the most varied - they include free nerve endings, tactile hair cells and complicated ENCAPSULATED END-ORGANS; - mechanoreceptors may be found in any part of the body such as the skin, muscle, gut; - you have already looked at the HAIR CELLS in the ear