general senses (theory) Flashcards
what are the 3 general stimuli plasmalemma receptors can be sensitive to?
- chemical
- electrical
- mechanical
what are the two categories of senses?
- general senses
- special senses
what are general senses?
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
what are special senses?
special senses include taste, smell, balance, hearing and vision
we have specialized organs to perceive these stimuli
receptor specificity
receptor specificity is given by the structure of the receptor and its sensitivity
what is a receptive field?
what is the difference between a large field and a small field?
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
what are the two types of receptor classification?
(constitutively active vs stimulus dependent)
- tonic receptors
- phasic receptors
tonic –> always on
phasic –> needs a stimulus to activate
ex… tonic –> photoreceptors of the eye
ex… phasic –> touch receptors of the skin
what are the 3 types of receptor adaptation?
- adaptation
- peripheral adaptation
- central adaptation
what is receptor adaptation?
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
what is receptor peripheral adaptation?
receptor responds strongly at first, then starts to decline
what is receptor central adaptation?
the receptor adapts within the CNS, you become consciously aware of a stimulus but it quickly disappears
what are 3 general sense receptor classifications?
- exteroceptors –> sense external environment
- proprioceptors –> sense body movement and position
- interoceptors –> sense internal body activity
ex… baroreceptors are a type of interoceptor
ex… thermoreceptors are a type of exteroceptor
what are 4 receptor classifications based on general stimuli type?
- nociceptors
- thermoreceptors
- mechanoreceptors
- chemoreceptors
what is a nociceptor?
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
what are the 3 types of pain that nociceptors can signal for?
- fast pain –> cuts and pricks
- slow pain –> burns and aches
- referred pain
what is referred pain
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
what are thermoreceptors?
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
what are mechanoreceptors?
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
what do tactile receptors perceive?
touch, pressure, and temperature
what are the two categories of tactile receptors?
- encapsulated
- unencapsulated
encapsulated tactile receptors
- meissner corpuscles (tactile)
- pacinian corpuscles (lamellated)
- ruffini corpuscles
meissner corpuscles are common in the fingertips, nipples, genitalia, lips
ruffini are common in the dermis
unencapsulated tactile receptors
- free nerve endings
- hair root plexuses
- merkel’s discs
merkel’s discs are in the stratum basale of the epidermis
free nerve endings are in the dermis
what are baroreceptors?
they sense stretching of the organs
- stomach
- small intestine
- urinary bladder
- carotid artery
- carotid sinuses
- aortic arch
- lungs
- large intestine
baroreceptors of the lungs
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
what are proprioceptors
they monitor the body’s position and joint movement
- monitor joint position
- monitor tendon and ligament tension
- monitor SKM contraction length
ex… intrafusal muscle spindle receptor and extrafusal muscle
what are chemoreceptors
respond to chemical changes (water and lipid soluble)
found in…
1. medulla
2. carotid arteries
3. aortic arch
chemoreceptors and acidosis
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
