module 5 - 13.3 sensory receptors

Question 1

what are sensory receptor cells?

Answer 1

cells that convert a stimulus they detect into an electrical impulse

Question 2

what are the 2 features of sensory receptors?

Answer 2

1. they are specific to a single type of stimulus
2. they are transducers as they transduce the stimulus energy into an electrical energy impulse

Question 3

what are the 4 types of mammalian receptor cells?

Answer 3

• mechanoreceptors
• chemoreceptors
• thermoreceptors
• photoreceptors

Question 4

what are chemoreceptor cells?

Answer 4

• a chemoreceptor cell transduces a chemical substance to generate an electrical impulse
• chemoreceptor cells detect chemicals external to the body e.g. odours
• they also detect chemicals that are internal to the body e.g. blood pH

Question 5

what are pacinian corpuscles?

Answer 5

a type of pressure receptor cell that are found in mammalian skin (skin receptor cells)

Question 6

what is an alternative name for pacinian corpuscles?

Answer 6

lamellar corpuscles - because of the laminations in their structure

Question 7

what are 3 other types of skin receptor cells?

Answer 7

1. Meissner’s corpuscles
2. Merkel cells
3. Ruffini corpuscles

Question 8

what is the function of pascinian corpuscles?

Answer 8

transduce mechanical energy into an electrical energy impulse in the sensory neurone

Question 9

what is the process of pascinian corpuscles transducing mechanical energy into electrical energy?

Answer 9

1. sensory neurone (ends in pascinian corpuscles) has special plasma membrane
2. stretch mediated sodium channel proteins in plasma membrane
3. when plasma membrane is stretched/pressurised, sodium channel proteins increase permeability to sodium ions as channel widens
4. when sensory neurone is in resting state, it has a voltage across plasma membrane (resting potential) as plasma membrane is polarised with positive charge outside cell
5. when pascinian corpuscle has pressure applied, plasma membrane of sensory neurone deforms and sodium channel protein is open
6. sodium ions flood into sensory neurone (facilitated diffusion)
7. this changes localised polarity (+ and -) of the voltage across localised part of plasma membrane (that part is depolarised)
8. results in generator potrential
9. causes action potenrial
10. action potential passes along sensory neurone

Question 10

in their normal state, what is the permeability of the sodium channel proteins?

Answer 10

sodium channel proteins have high impermeability to sodium ions because channel is too small (cant get back into the cells)

Question 11

what does it mean is the sensory neurone is in resting state?

Answer 11

it hasnt been stimulated by pascinian corpuscle

Question 12

what does “-“ mean?

Answer 12

NOT NEGATIVE, JUST LESS POSITIVE