116577
Descrição
Mapa Mental por harry_bygraves, atualizado more than 1 year ago
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Criado por harry_bygraves
mais de 11 anos atrás
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Receptors
- An animals internal and external enviroments are continually
changing. A dectectable change is called a stimulus. To
some extent all cells are sensitive to stimuli, but in animals
certain cells have to become especially sensitive to particular
stiimuli. These are called recpetor cells. they act as
tranducers, converting the energy of the stimulus into the
electrical energy of a nerve impulse which is transmitted
along the sensory neurone to the centeral nervous system.
- A pacinian corpuscle is a receptor sesnistive to change in pressure and touch. As such, it is called a
mechsnoreceptor. Pacinian corpuscles occur in the skin, tendons, mucles and joints of mammals. Each
corpuscle has a single sensory neurone, one end of which consists of capsule made of conentric rings
of connective tissue that acts as a pressure sensitive pad. Application of pressure against the
connective tissue deforms stretch-mediated sodium ion channel proteins., in the plasma membrane.
This causes an influx of sodium ions into the end of the sensory neurone. The sudden influx of sodium
ions reverses the potential difference across the plasma membrane. The inside becomes temporarily
postively charged, a process called depolarisation. The electrical potential created by the deformation is
proportional to the stimulus intensity. This graded potential is known as the generator potential.
- The pacinian corpuscle, like other receptors, respons only to
specific stimulus. It responds to mechanical deformation. It
does not respond to other stimuli such as temperature.
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