general senses (theory)

Question 1

what are the 3 general stimuli plasmalemma receptors can be sensitive to?

Answer 1

1. chemical
2. electrical
3. mechanical

Question 2

what are the two categories of senses?

Answer 2

1. general senses
2. special senses

Question 3

what are general senses?

Answer 3

general senses include touch, pressure, vibration, pain, temperature and proprioception

ex… the posterior white column of the spinal cord can sense fine touch, pressure, vibration, and proprioception

Question 4

what are special senses?

Answer 4

special senses include taste, smell, balance, hearing and vision

we have specialized organs to perceive these stimuli

Question 5

receptor specificity

Answer 5

receptor specificity is given by the structure of the receptor and its sensitivity

Question 6

what is a receptive field?
what is the difference between a large field and a small field?

Answer 6

a receptive field is the area of coverage of many receptors

large fields have receptors spread far apart which makes the stimulus difficult to locate

small fields have receptors close together, so it’s easier to localize the stimulus

Question 7

what are the two types of receptor classification?
(constitutively active vs stimulus dependent)

Answer 7

1. tonic receptors
2. phasic receptors

tonic –> always on
phasic –> needs a stimulus to activate

ex… tonic –> photoreceptors of the eye
ex… phasic –> touch receptors of the skin

Question 8

what are the 3 types of receptor adaptation?

Answer 8

1. adaptation
2. peripheral adaptation
3. central adaptation

Question 9

what is receptor adaptation?

Answer 9

if given a constant stimulus, an adaptive receptor will reduce sensitivity to the stimulus

ex… you will get used to swimming in a cold pool after a few minutes

Question 10

what is receptor peripheral adaptation?

Answer 10

receptor responds strongly at first, then starts to decline

Question 11

what is receptor central adaptation?

Answer 11

the receptor adapts within the CNS, you become consciously aware of a stimulus but it quickly disappears

Question 12

what are 3 general sense receptor classifications?

Answer 12

1. exteroceptors –> sense external environment
2. proprioceptors –> sense body movement and position
3. interoceptors –> sense internal body activity

ex… baroreceptors are a type of interoceptor
ex… thermoreceptors are a type of exteroceptor

Question 13

what are 4 receptor classifications based on general stimuli type?

Answer 13

1. nociceptors
2. thermoreceptors
3. mechanoreceptors
4. chemoreceptors

Question 14

what is a nociceptor?

Answer 14

nociceptors sense pain

these receptors are associated with free nerve ending (non encapsulated) receptors of the dermis

nociceptors respond to different kinds of pain sources…
1. extreme temps
2. mechanical damage
3. chemicals

Question 15

what are the 3 types of pain that nociceptors can signal for?

Answer 15

1. fast pain –> cuts and pricks
2. slow pain –> burns and aches
3. referred pain

Question 16

what is referred pain

Answer 16

referred pain is the pain felt by an internal organ that is felt at different places on the surface of the body

ex… a heart attack will present itself with medial left arm and forearm pain

ex… liver and gallbladder pain will present itself ast right shoulder pain

Question 17

what are thermoreceptors?

Answer 17

thermoreceptors respond to changes in temperature and are phasic receptors, but they can adapt to stable temps

they are present in the dermis, SKM, liver and hypothalamus

recall that the hypothalamus is a center for temperature control

thermoreceptors are associated with free nerve endings

Question 18

what are mechanoreceptors?

Answer 18

mechanoreceptors respond to distension/disturbance in anyway of the plasmalemma

ex… pulling, twisting, compression

there are 3 types of mechanoreceptors…
1. baroreceptors
2. tactile receptors
3. proprioceptors

Question 19

what do tactile receptors perceive?

Answer 19

touch, pressure, and temperature

Question 20

what are the two categories of tactile receptors?

Answer 20

1. encapsulated
2. unencapsulated

Question 21

encapsulated tactile receptors

Answer 21

1. meissner corpuscles (tactile)
2. pacinian corpuscles (lamellated)
3. ruffini corpuscles

meissner corpuscles are common in the fingertips, nipples, genitalia, lips

ruffini are common in the dermis

Question 22

unencapsulated tactile receptors

Answer 22

1. free nerve endings
2. hair root plexuses
3. merkel’s discs

merkel’s discs are in the stratum basale of the epidermis

free nerve endings are in the dermis

Question 23

what are baroreceptors?

Answer 23

they sense stretching of the organs

1. stomach
2. small intestine
3. urinary bladder
4. carotid artery
5. carotid sinuses
6. aortic arch
7. lungs
8. large intestine

Question 24

baroreceptors of the lungs

Answer 24

we have baroreceptors in our lungs to tell us when to stop expanding them, otherwise they’d explode because our simple squamous epithelium (alveoli) can only take so much expansion

Question 25

what are proprioceptors

Answer 25

they monitor the body’s position and joint movement

1. monitor joint position
2. monitor tendon and ligament tension
3. monitor SKM contraction length

ex… intrafusal muscle spindle receptor and extrafusal muscle

Question 26

what are chemoreceptors

Answer 26

respond to chemical changes (water and lipid soluble)

found in…
1. medulla
2. carotid arteries
3. aortic arch

Question 27

chemoreceptors and acidosis

Answer 27

our normal blood pH is 7.34-7.45

acidosis is a decrease in blood pH due to increased H+ and CO2

increased CO2 causes us to increase our respiratory rate to expel more CO2

increased H+ causes us to increase excretion by the kidneys