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Sensory System Flashcards

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1
Q

Sensory cells

A

specialized cells designated to obtain information about the environment, linked to receptor proteins in their membranes and to the opening and closing of ion channels.

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2
Q

Ancient Channels (first ion channels to evolve were most likely stretch-sensitive channels also referred to as Mechanically-gated channels serve as?

A

served as osmotic stress sensors, activated when a cell was deformed by changes in cell volume.
**deformation sensors in E. coli.(sensitive to osmotic stress)

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3
Q

Voltage-gated channels also ancient found in

A

yeast cells

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4
Q

The three primary roles of sensors

A
  1. Exteroreceptors
  2. Interoreceptors
  3. Proprioceptors
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5
Q

Exteroreceptors

A

detect external stimuli; (external envirinment)

light, chemical, touch, temperature, sound

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6
Q

Interoreceptors

A

Located deep with in the body; in blood vessels & gut
- detects information about internal body fluids for
homeostasis such as; blood pressure & hydrogen ion concentration (PH)

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7
Q

Proprioceptors

A

located in inner ear (deals with equilibrium)
detect movement & body position
(touching your nose with your eyes closed)

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8
Q

Humans have receptors that detect only a limited number of existing energy forms, why don’t we detect everything?

A
  • None of our receptors respond to the latter energy forms

- Cerebral cortex manipulates & compares information

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9
Q

What is the only way afferent neurons send information?

A

**through the CNS by action potentials

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10
Q

Afferent neurons have receptors where?

A
  • at their peripheral endings that respond to stimuli on both the external world and internal environment
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11
Q

Transduction is the process of what?

A

receptors converting other forms of energy in to electrical energy (action potential)
**energy conversion process

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12
Q

Receptors have adequate stimulus which means?

A

Each receptor is specialized to respond more readily to one type of stimulus - but may perceive others
Ex: Hit in the eye»stars due to mechanical stimulation - photo receptors

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13
Q

7 different forms of receptors

A
  1. Photoreceptors
  2. Mechanoreceptors
  3. Cemoreceptors
  4. Thermoreceptors
  5. Nociceptors
  6. Electroreceptors
  7. Magnetoreceptors
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14
Q

Photoreceptors sensitive to?

A

light

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15
Q

Mechanoreceptors sensitive to?

A

mechanical energy such as;

- touch, stretch, hair cells, fish lateral line, baroreceptors

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16
Q

Chemoreceptors sensitive to?

A

Sensitive to specific chemicals

  • Chemical receptors include the exteroreceptors for smell and taste as well as
  • interoreceptors that detect O2 and CO2 concentrations in the blood, and the osmotic concentration of key fluid molecules
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17
Q

Thermoreceptors sensitive to?

A

Heat and Cold

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18
Q

Nociceptors sensitive to?

A

pain (pain receptors)
- sensitive to tissue damage such as pinching or burning and intense stimulation of any receptor is
perceived as painful

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19
Q

What does it mean if something is a compound sensation?

A

perception arises from several, simultaneously activated, primary sensory inputs
**Example- Wetness; comes from the perception of touch, pressure, and thermal receptor input.
(no such thing as wet receptors)

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20
Q

Voltage-gated, mechanically-gated and chemically-gated channels can be found where?

A

Found everywhere throughout the body; in all types of cells and organisms; from primitive (bacteria) to advanced (humans)

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21
Q

Receptors are either…

A
  1. Specialized afferent endings

2. Separate cells associated with peripheral ending of a neuron

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22
Q

What does stimulation of a receptor cause?

A

It alters its membrane permeability causing nonselective opening of all small ion channels

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23
Q

What mechanism is used to distinguish each receptor type?

A

It is the mechanism for changing the permeability that distinguishes each receptor type

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24
Q

Predominant effect is?

A

an inward flux of Na+, which depolarizes the receptor membrane

**Exceptions exist – photoreceptors are hyperpolarized on stimulation

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25
Local depolarizing change in potential is known as? | And what is it?
- Receptor potential or generator potential - It is a specialized cell ending of an afferent neuron - The receptor potential is a graded potential whose amplitude & duration vary depending on strength & rate of application or removal of the stimulus
26
The stronger the stimulus, causes?
greater permeability change and the larger the receptor potential ** Receptor potentials have no refractory period – therefore can get summation
27
Action potential does not take place at the receptor, where does it take place?
Receptor potential initiates action potential in | adjacent neuron producing an opening of Na+ channels
28
The means by which the Na+ channels are opened differ depending on?
whether the receptor is a separate cell or specialized afferent ending
29
Separate cell
(like retina) - receptor potential that triggers release of a neurotransmitter - Binding of the chemical messenger with specific protein receptor sites on the afferent neuron which opens chemical messenger-gated Na+ channels in adjacent neuron
30
Specialized afferent endings
current flow goes to adjacent cell to open voltage-gated Na+ channels. Adjacent cell brought to threshold >> initiation of action potential **A larger receptor potential cannot bring about a larger action potential (because all-or-none) – but can produce more firings of action potentials
31
One way stimulus strength is coded?
- The stronger the stimulus the greater the frequency of action potentials - Stimulus strength is also reflected by the size of area stimulated. Ex. Light touch versus forceful touch (stronger stimuli affect larger areas)
32
Stimulus Intensity =
Freq. of Action Potential + # of Receptors Activated
33
2 types of receptors – based on adaptation
1. Tonic receptor | 2. Phasic receptor
34
Tonic receptor
No adaptation or slow adaptation (maintained information about stimulus is important) (Ex. Muscle stretch proprioceptors monitor muscle length to help maintain balance and posture)
35
Phasic receptors
Adapt rapidly – adapts by no longer responding – but removal of stimulus receptor responds with slight depolarization (off response) **Important signaling a change in stimulus intensity (Example with horse and saddle adaptation)
36
``` Pacinian Corpuscle (PC) How do they adapt? ```
- Rapidly adapting skin receptors that detect vibration & pressure in skin - Adapts using mechanical & electrochemical components
37
Mechanical Component of Pacinian Corpuscle
– depends on the physical properties of the receptor PC consists of concentric layers of connective tissue (onion-like) around peripheral terminal of an afferent neuron. 1st applied pressure >> receptor potential in terminal reflects the stimulus intensity Continued stimulation >> slippage of layers (like steady pressure on onion) – as a result – filters out steady applied pressure >> no longer responds with a receptor potential ** This is Accomodation
38
Two things a stimulus relies on?
Adaptation (the rate at which it adapts) and which receptor
39
The Electrochemical Component of Pacinian Corpuscle
– Change in ionic movement across receptor - Na+ (Primary ion dealing with senses) channels that opened in initial response – slowly inactivated >> decreased inward flow of Na+ that was responsible for depolarization
40
With prolonged depolarization what happens?
voltage-gated Na+ channels cannot open, regardless of stimulus intensity
41
Olfactory adaptation
- Olfaction – adaptation to pig smell on clothes - Binding of odorant molecule to receptor, opens cation channels & slowly deactivates a protein that closes ion channels.
42
Some olfactory smells that do not adapt means they are?
Potentially dangerous substances Ex. Rotting food and skunk; - smell stays until the odor molecule decays
43
Receptive field
Somatosensory neuron only responds to stimulus within a certain region of skin; does not respond to things around it
44
Field size varies inversely with?
- Density of receptors in region (i.e., the more closely receptors are spaced the smaller the area of skin each monitors & the smaller the area the greater the acuity or discrimination. * *Acuity and discrimination increase with stimulus
45
Lateral Inhibition
- increases contrast & localization; capacity of an excited neuron to reduce the activity of its neighbors * *stimulate one area and inhibit firing in surrounding area
46
Mammalian retina - In dark, a light stimulus - enhanced by different photoreceptors (rod cells). (Rods in the center of stimulus) does what?
- transduce the "light" signal >> brain
47
Rods on outside of stimulus send "dark" signal >> brain causing?
- contrast creates a sharper image
48
What is the dominant signal for birds
Photorecepton; light Nearly all organisms are light sensitive – but with large variances in sensitivity. Photopigment molecules used by almost all animals
49
What animal has the largest eye?
Ostrich; terrestrial animal
50
Retina
- Eyes capture patterns of illumination >> optical picture on a layer of sensitive cells (retina) - Retinas – similar across vertebrates
51
Vertebrate Eye
a fluid-filled sphere enclosed by three specialized tissue layers
52
The enclosed layers of the eye include? (3 of them)
1) Sclera & cornea (outermost) 2) Choroid, ciliary body, & iris 3) Retina
53
Sclera
connective tissue outer structure of eye; gives it the white color
54
Cornea
transparent portion that light enters through | outer structure
55
Choroid
pigmented middle layer under sclera with blood vessels to nourish retina – becomes specialized into ciliary body & iris
56
Retina
inner most coat with outer pigmented layer & inner nervous tissue layer that contains photoreceptors (rods & cones) **Pigmented areas absorb light
57
The 2 Fluid-filled compartments separated by lens
1. Anterior chamber | 2. Posterior chamber
58
Anterior chamber
– contains aqueous humor (carries nutrients for cornea & lens)
59
Posterior chamber
– contains vitreous humor (helps maintain spherical shape of eyeball
60
Mammalian retina
– well vascularized & thinner compared to birds & reptiles
61
Iris
thin, pigmented smooth muscle that is a ring within – aqueous humor * *Iris muscles determine pupil size * *Iris also controls the amount of light entering the eye
62
What determines eye color?
Iris Pigment
63
Pupil
Center of iris through which light passes | ** the bigger the pupil indicates more stressed out
64
Accomodation is the ability to
- adjust lens to focus near & distant objects * *Lens changes in birds, mammals, and some reptiles - Smooth muscle controlled by ANS
65
Circular Lens
– Parasympathetic – Ciliary muscle CONTRACTION – deals with near vision **Bright light >> contraction of circular >> smaller pupil – radials relaxed
66
Radial Lens
– Sympathetic (fight or flight; stress linked>> enlarged pupil) – Ciliary muscle RELAXATION – Distant vision **Dim light >> radials shorten – pupils enlarge
67
Major function of the eye
focus light on rods & cones where photoreceptor cells are located These receptors are an extension of CNS & not a peripheral organ
68
During embryonic development – retinal cells do what?
retinal cells back out of nervous system – so are facing BACKWARDS

Physiology (9 decks)

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