Physiology 5 sensory receptors

Question 1

The function of the nervous system can be categorized to what?

Answer 1

Lower and Higher functions

Question 2

The higher brain function is for what?

Answer 2

Performed by brain and it is for cognition and emotions

Question 3

The lower functions are performed from what and function?

Answer 3

CNS and PNS include the motor functions, automatic functions(which does not involve consciousness ex: regulation of circulation)) and sensory functions(detection and processing of sensory information). The sensory function include the special senses (seeing, hearing and smelling) and the somatosensation which include perception of body position, vibration, touch, pain and temperature. This lecture will focus on the processing of somatosensation particularly touch and position.

Question 4

how our body detect different stimuli from the outside world and within our body?

Answer 4

This is made possible via sensory receptors.

Question 5

What is a stimulus?

Answer 5

It is a form of energy

Question 6

How do neurons transmit information to the CNS from a stimulus?

Answer 6

Via action potential propagation. Receptors transform the different forms of energy into electrical signals.

Question 7

What is adequate stimulus and give example.

Answer 7

Each type of receptor is most responsive to a specific form of energy, called adequate stimulus which when stimulate the receptor, it gives rise to a particular sensation
e.g. rods & cones are stimulated by light not heat

Each type of receptor is only responsive to one type of stimulus its adequate stimulus. E.g. receptors in the eye are sensitive to light, receptors in the ear to sound waves and warmth receptors in the skin to heat energy. Because of this differential sensitivity we cannot see with our ears or hear with our eyes. Some receptors can respond weakly to stimuli other than their adequate stimulus but even when activated by a different stimulus a receptor still give rise to the sensation usually detected by that receptor type e.g. the adequate stimulus for eye receptors (photoreceptors) is light to which they are exquisitely sensitive but these receptors can also be activated to a lesser degree by mechanical stimulation. . When hit in the eye a person often see a stars because the mechanical pressure stimulates the photoreceptors. Because receptors typically are activated by their adequate stimulus, the sensation usually correspond to the stimulus modality

Question 8

Can some receptors respond to other stimuli other than their adequate stimulus?

Answer 8

Yes, Ex: the adequate stimulus for eye receptors (photoreceptors) is light to which they are exquisitely sensitive but these receptors can also be activated to a lesser degree by mechanical stimulation. . When hit in the eye a person often see a stars because the mechanical pressure stimulates the photoreceptors. Because receptors typically are activated by their adequate stimulus, the sensation usually correspond to the stimulus modality

Question 9

What are the types of sensory receptors?

Answer 9

1- Mechanoreceptors
2- Thermoreceptors
3-Nociceptors
4- Electromagnetic receptors
5- Chemoreceptors

Question 10

What is the stimulus and modality of Mechnoreceptor?

Answer 10

Mechanical

Touch

Question 11

What is the stimulus and modality of thermoreceptors?

Answer 11

Tempereture

Hot or cold

Question 12

What is the stimulus and modilty for Nociceptors?

Answer 12

Physical or chemical damage

Pain

Question 13

What is the stimulus and modality of electromagnetic receptor?

Answer 13

Light

Vision

Question 14

What is the stimulus and modality of Chemoreceptors?

Answer 14

Chemical energy

Taste,smell,oxygen levels, osmolality of the fluids, Co2 concentration, etc…

Question 15

How are sensory receptors classified?

Answer 15

According to their stimulus type and modality.

They can also be classified by cell structure into:
1- Free nerve endings (e.g Nociceptive)
2- Encapsulated nerve endings (eg Mechanoreceptors)
3- Specialized nerve endings( eg Photoreceptors)

Question 16

What makes a sensory neuron specialized to respond to specific stimulus?

Answer 16

The shape of the dendrite and the receptor type

E.g. Mechanoreceptors have vary in their dendrites hence specialized to respond to specific stimulus. Pacinian receptors respond to vibration while Meissner receptors to pressure.

Question 17

Add meissners corpuscle here

Answer 17

1

Question 18

Add Pacinian corpuscle here

Answer 18

D

Question 19

Add Ruffini organ here

Answer 19

D

Question 20

Add Merkel disks here

Answer 20

Dd

Question 21

Add free nerve ending here

Answer 21

D

Question 22

What sensory information is relayed to consiousness and what isn’t?

Answer 22

Somatic sensory receptors detect information that you are aware of it while visceral sensory neurons related information usually do not reach consciousness

Question 23

What are examples of somatic sensory neurons information that reach the consiousness?

Answer 23

Proprioception:
1- Muscle spindle
2- Joint receptors
3- Golgi tendon
4- Vestibular apparatus

Exteroceptors:
1- Chemoreceptors
2- Photoreceptors
3- Mechanoreceptors
4- Thermoreceptors
5- Nociceptors

Question 24

Examples of Visceral sensory neurons?

Answer 24

Interceptors(visceroceptors):

1- Chemoreceptors
2- Nociceptors
3- Baroreceptors
4- Osmoreceptors
5- Visceral stretch reeceptors
6- Iritant receptors

Question 25

What are the divisions of somatosensory receptors?

And what is the difference?

Answer 25

Exteroceptors
Proprioceptors

Somatic sensory neurons can be further divided into exteroceptors and proprioceptors. exteroceptors provide information about external environment/world. E.g. photoreceptors tells us what the world looks like. Chemoreceptors tell us about the world around us including smell by olfactory receptors, taste buds (whether sweet, sour, salty bitter etc).Mechanoreceptors inform us about anything touching us including touch and pressure receptors, vibration, tickle and itch receptors and auditory receptors which detect vibration in the air (sound). Thermoreceptors inform us about heat whether hot or cold. Nociceptors tell us about injuries.

Proprioception tell us about position and movement of the head and body in space.these are found in our skeletal muscles, tendon and joints. Vestibular apparatus are special proprioceptors that tell us about balance and equilibrium and found in our inner ears.

Question 26

What is the Vestibuluar apparatus for? And where are they found?

Answer 26

They are special proprioceptors that tell us aboutbalance and equilibrium and are found in inner ear.

Question 27

What is the other name of Visceral receptors?

Answer 27

Interceptors

Question 28

Read this general info about visceral sensory neurons…

Answer 28

Visceral (internal organs) sensory neurons inform us about what’s going on inside our body and generally this information does not reach our consciousness. Interceptors include (a) chemoreceptors that monitor O2, Co2, acidity and glucose in our bloodstream. Also we have (b) pain sensory neurons in our internal organs although poorly defined (c) baroreceptors which monitor blood pressure (d) osmoreceptors which monitor tonicity of body fluid (hypertonic or hypotonic status)(e) visceral stretch receptors which respond when our bladder or rectum full to urinate or defecate and (f) irritant receptors which trigger sniezing and coughing.

Question 29

What is the name of the conversion of energy stimulus into electrical signals? And what is the fundemental mechanism of it?

Answer 29

Sensory transduction.

Stimulus>Membrane conductance change> Receptor potential(graded)> AP

Question 30

Picture slide 12

Answer 30

A