Sensory Receptors

Get Started. It's Free
or sign up with your email address
Sensory Receptors by Mind Map: Sensory Receptors

1. Sensory Adaptation is one form of Integration

1.1. Phasic Receptors

1.1.1. quickly adapt

1.1.2. frequency of action potential will diminish or stop opnce the stimulus is unchanging

1.1.3. alert us to changes in sensory stimuli

1.1.4. responsible for how we cease paying attention to smth getting used to a furry jacket

1.2. Tonic Receptor

1.2.1. adapt slowly or not at all

1.2.2. u dont get used to pain

1.2.3. pain receptors and baroreceptors

1.2.4. keeps maintained information so you dont adopt or get used to the stimulus getting used to pain is not a good thing

1.3. Exteroreceptors

1.3.1. receptors that monitor the outside envi

1.3.2. phasic receptor

2. Alternative Classification Used by Sensory Physiologists

2.1. Definition

2.1.1. certain recording techniques now make it possible to separate the Type Aa fibers into 2 subgroups but the same recording techniques cannot distinguis easily between Ab and Ag fibers

2.2. Group 1a Fibers

2.2.1. from the annulospiral endings of muscle spindles

2.2.2. about 17 microns in diameter

2.2.3. a-type A fibers in the general classification

2.3. Group 1b Fibers

2.3.1. from Golgi Tendon organs

2.3.2. about 16 microemeters in diameter

2.3.3. also a-type A fibers

2.4. Group II Fibers

2.4.1. from the most discrete cuteaneous tactile receptors

2.4.2. from the flower spray endings of the muscle spindles

2.4.3. 8 micrometers in diameter

2.4.4. they are b- and g- type A fibers in the General Classification

2.5. Group III Fibers

2.5.1. carrying temperature, crude touch, and pricking pain sensations

2.5.2. about 3 micrometers in diameter

2.5.3. they are d-type A fibers in the general classification

2.6. Group IV Unmyelinated Fibers

2.6.1. carrying pain, itch, temperature, and crude touch sensation

2.6.2. 0.5 to 2 micrometers in diameter

2.6.3. they are type C fibers in the general classification

3. Mechanism of Adaptation

3.1. Readjustment in the Structure of the Receptor Itself

3.1.1. Pacinian Corpuscle viscoelastics structure when a sudden force is applied to one side of the corpuscle it will transmit force instantly and directly to the same side of the central core

3.1.2. Even if another pressure is applied on all sides of the central core, receptor potential is no longer elicited

3.1.3. the disturbance of the central core fiber signals the effect of compression as well as signaling the onset of compression

3.2. Accommodation in the Nerve Fiber Itself

3.2.1. due to inactivation of Na channels in the nerve fiber membrane where the current flow itself though the channels in some way causes them to close gradually

4. Adaptation of Different Types of Receptors

4.1. Extremely Rapid Adaptation

4.1.1. Pacinian Corp.

4.1.2. Meissner's Corp

4.1.3. Hair Receptores

4.2. Slow Adaptation

4.2.1. Touch Merkel's Ruffini's

4.2.2. Muscle spindles

4.2.3. Joint capsules receptors

4.2.4. Others receptors of macula in vestibular apparature pain receptors nociceptors baroreceptors of the arterial tree chemoreceptors of the carotid and aortic bodies

4.2.5. Because ther slowly stransmit info for hours or even days, they are called the Tonic Receptors

4.3. Extent of Adaptation

4.3.1. Pacinian corp adapt to "extinction" within a few hundredth of a second

4.3.2. Hair base receptors adapt to extinction in a second or more

4.3.3. Carotid and Aortic Baroreceptors adapt completely in 2 days

4.3.4. Receptors for pain and some chemo receptos never fully adapt

5. Transmission of Signals of Different Intensity in Nerve Tracts - Spatial and Temporal Summation

5.1. one characteristic that must always be conveyed is the

5.1.1. signal intensity like the intensity of pain

5.2. different gradations of intensity can be transmittes by

5.2.1. increasing numbers of parallel fibers Spatial Summation increases signal strength by using progressively greater numnbers of fibers A section of skin iss innervated by a large number of parallel pain fibers each of them arborizes into hundreds of minute free endings that serve as pain receptors The entire cluster of fibers from one pain fiber frequently covers an area of skin as large as 5 cm in diameter Number of endings is large in the center of the field but diminishes towards the peripheryu the arborizing fibrils will overlsap those from other pain fibers Ex: Pinprick The stronger signals spread to more and more fibers

5.2.2. sending more AP along a single fiber Temporal Summation A seconf meansd for transmitting signals of increasing strength by increasingf the frequence of nerve impulses in each fiber

6. Transmission and Processing of Signals in Neuronal Pools

6.1. CNS is composed of thousands to millions neuronal pools

6.2. some would have a few neurons and some have vast numbers

6.3. the entire cerebral cortex could be considered to be a single large neuronal pool

6.4. others would be the basal ganglia, and the specific nuclei in the thalamus, cerebellum, mesencephalon, pons, and medulla

6.5. the entire dorsal gray matter of the spinal cord could be considered one long pool of neurons

6.5.1. each neuronal pool would have its own special organization that causes it to process signals in its own unique way

6.5.2. allowing total consortium of pools to achieve multitude of functions of the nervous system

6.6. Depsite their differences in function, the pool also have manyt similar principles of function

7. Divergence of Signals Passing Through Neuronal Pools

7.1. Definition

7.1.1. it is important for your weak signals that enter the neuronal pool to excite far greater numbers of nerve fibers leaving the pool Divergence

7.2. Types

7.2.1. Amplifying Divergence input signal spreads to an increasing number of neurons as it passes through successive orders of neurons in its path this type of divergence is characteristic of the corticospinal pathway in its control of skeletal muscles with a single large pyramidal cell in the motor cortex capable, under highly facilitated conditions of exciting as much as 10 000 muscle fibers

7.2.2. Multiple Tracts transmitted in 2 directions from th epool can be transmitted up the dorsal columns of the spinal cord and takes 2 courses in the lower part of the brain Into the Cerebellum On through the lower regions of the brain to the thalamus and cerebral cortex Likewise, in the thalamus, almost all sesnory information is relayed both into deeper structurs of the thalamus and to the discrete regions of the cerebral cortex

8. Convergence of Signals

8.1. Def

8.1.1. signals from multiple inputs uniting to excite a single neuron

8.2. Convergence from a Single Source

8.2.1. multiple terminals from a single incoming fiber tract terminate on the same neuron

8.2.2. this is importans bc neurons are almost never excited from just on input terminal

8.2.3. but action potentials converging on the neuron from multiple terminals provide enough spatial summation to bring the neuron to the threshold required for discharge

8.3. Convergence can also Result from Input Signals (Excitatory or Inhibitory) from Multiple Sources

8.3.1. ex: the interneurons of the psinal cord can receive convergin signals from the following Peripheral Nerve fibers entering the cord propriospinal fibers passing from one segment of the cord to another corticospinal fibers from the cerebral cortex several other long pathways descendning from the brain into the spinal cord

8.3.2. The signals from the interneurons converge on the anterior motor neuron to control muscle funtcion

8.3.3. the convergence allows summation of information from differenct sources, result response is a summated effect od all the diff types of info

8.3.4. convergence is one of the most important means by which the CNS correlates, summates, and sors different tyope of information

9. Neuronal Circuit

9.1. sometimes an invcoming signal to a neuronal pool causes an output exitatory signal goin in one direction

9.1.1. at the same time an inhibitoy signal goin elswhere yuh

9.2. this type of circuit is characteristic for a ll controlling all antagonistic pairs of muscles and it is the

9.2.1. reciprocal inhibition circuit

9.3. Pics

9.3.1. 1

10. Sensory Receptors

10.1. Vision

10.2. Hearing

10.3. Smell

10.4. Taste

10.5. Touch

11. Receptors

11.1. Cell Membrane Receptor Proteins

11.2. Specialized Receptors

11.2.1. Central Receptors Eyes (Vision) Ears (hearing, equilibrium) Nose (smell) Tongue (taste)

11.2.2. Peripheral Receptors Chemoreceptor pH gases chemicals Osmoreceptor osmolarity Thermoreceptor temperature Baroreceptor pressure Proprioceptor body position Other mechanoreceptors pain vibration touch

12. Definition

12.1. We see the world via our senses so our sensory receptors help us receive and analyze such

12.2. Sensation Terms (?)

12.2.1. Sensation State of awareness of stimulus Parts?? Stimulus Receptor Impulse Conducted Translation

12.2.2. Awareness When a stimulus is being deteccted by the body below the level of cosciousness such as change in blood pressure or blood pH

12.2.3. Perception when the stimulus reaches your conscious ness like pain, hunger, sight sound etc

13. General Sensory Receptor Structure

13.1. Free Nerve Endings

13.1.1. Dendrites found throughout other cells and ttissues for carrying sensations od pain temp and touch

13.2. Encapsulated Nerve Endings

13.2.1. dendrites with special supporting structures Mechanoreceptors Proprioceptors

13.2.2. Pacinian Corpuscle

14. Classification of Receptors

14.1. Complexity

14.1.1. Simple Receptors single modified densdrite general senses touch pressure pain vibration temperature

14.1.2. Complex highly modified dendrites organized into complex structures ears eyes special senses vision hearing smell taste

14.2. Location

14.2.1. Externoceptors located on the body surface to detect external stimuli pressure, pain, temp, touch

14.2.2. Visceroreceptors viscero cortex ; internal stimuli blood pressure pain fullness internal organs

14.2.3. Proprioceptors in joints and muscles also in vestibular structures and seicircular canals of the inner ear limb and body position and movement

15. Differential Sensitivity of Receptors

15.1. how would two types of receptors detecty different stimuli

15.1.1. by differential sensetivity

15.2. some receptors will be highly responsive to some stimulus but not at all to others

15.3. rods and cones in eyes respond to light but no to heat fluctuations or blood pressure changes

15.4. osmoreceptors of the supraoptuc nuclei in the hypothalamus detect minute chandes in the osmolality of the body fluids but dont respond to sound stimuli

15.5. pain receptors in skin do not respond to touvh or prssure but immedaiately react when there is damage

15.5.1. like cold vs frostbite

16. Modality of Sensation "The Labeled Line" Principle

16.1. each of the senses we feel is called the modalities of sensation

16.2. despite our experiences, all them are still just transmitted by nerve fibres as impulses

16.3. how do theu know different modalities of sensation?

16.3.1. each nerve tract terminates at a specific point the type of sensation felt when a nerve fiber is stimulated is determined by the point in the nervous system where it leads

16.4. The specificity of nerve fibers for transporting only one modality of sensation is called the

16.4.1. labeled line principle

16.5. example

16.5.1. pain is pain, no matter what the stimulus is u still feel the sensation of pain

17. Mechanoreceptors

17.1. Skin Tactile Sensibilities (epidermis and dermis)

17.1.1. Free Nerve Endings

17.1.2. Expended Tip Endings merkell's discs

17.1.3. spray endings Ruffini's endings

17.1.4. encapsulaten endings Meissner's corpuscles Krause's corpuscles

17.1.5. hair end organs

17.2. Deep Tissue Sensibilities

17.2.1. Free Nerve endings

17.2.2. Expanded tip ednsings Spray endings Ruffinis Endings

17.2.3. encapsulated endings Pacinian corpuscles

17.2.4. muscles endings muscles spindles golgi tendon receptors

18. Transduction of Sensory Stimuli Into Nerve Impulses

18.1. Local electrical currents at nerve endings

18.1.1. receptor potentials

18.2. all sensory receptors have one feature in common

18.2.1. whatever the typre of stimulus that excites the receptor the immediate is to change the membrane electrical potential this change is called a receptor potential

19. Sensations: Receiving Messages

19.1. Stimuli

19.1.1. what messages can be received

19.2. anything that can excite a receptor is a stimulus

19.2.1. sound

19.2.2. light

19.2.3. heat

19.2.4. etc

20. Somatic Sensory Pathways

20.1. Posterior Column Pathway

20.1.1. carries fine touch, pressure, and proprioceptive

20.1.2. axons ascend in fasciculus gracili and cuneatus

20.1.3. relay info to the thalamus via medial lemniscus decussation

20.2. Anterolateral Pathway

20.3. Spinocerebellar Pathway

21. Mechanism by Which Receptor Potential is Produced in the Pacinian Corpuscle

21.1. stimulus like deformation of a part of the central fiber (tip) by compression

21.1.1. opens Na+ channels Na+ diffuse to the interior of the nerve fiver (causing positivtiy) local circuit current flow that spreads sa nerve fiber starting at the first node of Ranvier in the capsule <-- now mahimo na sha ug receptor potential

21.2. Sequence of Events in a Receptor

21.2.1. Stimulus Receptor Protein Acitivated Enzyme Cascade

21.2.2. Picture Events