COM1 Physiology C47 week 2 Flashcards by Shaylei M

Name the 5 basic types of sensory receptors

Mechanoreceptors
-Thermoreceptors
-Nociceptors
-Electromagnetic receptors
-Chemoreceptors

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What do mechanorecpetors detect

Mechanical compression or stretching

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What do thermorecpetors detect

Detect temperature changes

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What do nociceptors detect

Pain from physical or chemical damage

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What do electormagnetic receptors detect

Detect light in the retina

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What do chemoreceptors detect

Taste,smell,blood oxygen levels,osmolality+ chemical composition

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Explain the differential sensitivity of receptors

Each receptor is highly sensitive to its specific stimulus and unresponsive to other types

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What is each type of sensation called

Modaliity

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Do all nerve fibers transmit the same kind of impulses

Yes

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What does the percieved sensation depend on

Where the fiber terminates in the brain

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What is the receptor potential

Change in potential

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What do receptor potentials initiate when they exceed the threshold

Initiate a nerve

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Name the 4 mechanisms that can excite sensory receptors

Mechanical deformation
Chemical activation
-Temperature changes
Electromagnetic radiation

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Explain how mechanical deformation excites sensory receptors

By Streching opens ion channels

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Explain how chemical activation excites sensory receptors

-The binding of molecules opens ion channels

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Explain how temperature changes excite snesory receptors

Alter membrane permeability

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Explain how electromagnetic radiation excites sensory receptors

The light alters retinal receptor proteins

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What does a greater receptor potential lead to

Higher frequency of action potentials which lead to sensory signals

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What does pacinian corpuscle contain

Central nerve fibre surrounded by multiple capsule layers

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What is the effect of compression of the Pacinian corpuscle

Compression of the corpuscle deforms the central fibre, triggering receptor activity

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Is the tip of the pacinian corpuscle myelinated or unnyelinated

Unmyelinated

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When does the tip of the fiber of the pacinian corpuscle become myelinated

Before entering the peripheral sensory nerve

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Explain the mechanism of receptor potential generation (how it’s generated) in Pacinian corpuscle

Compression deforms the capsule , opening ion channels in the finer membrane
Na enters, creating a positive charge inside the finer
This leads to local current flow towards the first node of ranvier, triggering an action potential
Action potential then travels to Nervous system

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Explain the relationship between stimuli and receptor potential

Strong stimuli means higher receptor potential generation

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Explain the responses of snesory receptors to stimuli

- Initially they respond strongly, but the response gradually decreases or stops

Name 3 mechanims by which receptors adapt

- Rapid Adapting receptors - Slow adapting receptors -Non adapting receptors

# sensory receptors reduce Explain the adaption of receptors

Sensory receptors reduce their response to a continuous stimulus over time. Initially, they fire rapidly, but their response decreases gradually.

What is the basic function of Rapid adapting receptors

- Stop responding quickly

What is the basic function of slow adapting receptors

- They continue responding for longer periods

Explain the basic function of non adapting receptors

They do not fully adapt as their function is crucial for survival

Give an example of rapid adapting receptors

Pacinian corpuscles

Give an example of slow adapting receptors

muscle spindle

Name 2 mechanisms of Adaptation

- Mechanical adjustment -Electrical Adjustment

Explain what happens in mechanical adjustment

- Structural changes in receptors

Explain what happens in Electrical accommodation

- Sodium channels in nerve fibers gradually inactivate, reducing signal transmission

Explain how tonic(slow) adapting receptors act in relation to a stimulus

- Continuosuly transmit signals as long as stimulus is present

What is th eimportance of Slow/Tonic Adapting recepots

- Help mainyain awareness of body position and funcrion

Explain how rapid/phase adapting receptors act in relation to stimulis

- Respond only when stimulatus strength changes

Explain the importance of Phas/ Rapid acting receptors

- Detect motion and rate of chnage , not constant stimuli

Give 2 examples of neuronal pools

-Cerebral cortex -basal ganglia

Explain how neurons sends signals

The input fibers branch out sending mini signals to many neurons in the pool

Explain what is a suprathreshold stimulus

- If the stimulus is string enough it causes a neuron to fire

Explain what a subthreshold stimulus is

- If the stimulus is not sring enough,m it wont fire a neuron, but facilitiating it ( making it more excitable)

Name the 3 different zones in the neuronal pool

- Discharge zone -Facilitated zone -Inhibitory zone

What happens in the dischage zone in the neuronal pool

- The area where neurons are stringly excited

What happens in the Facilitated zone in the neuronal pool

Where neurons are helped but not excited to the threshold

What is the inhibitory zone in the neuronal pool

- Where certain fibers ihibit rather than excite neurons

What does divergence of signals mean

- When 1 message spreads to many neurons

Name the 2 types of divergence

- Amplifying divergence -Divergence into Multiple tracts

Explain what happens in Amlifying divergwnce

The signal spreads to an increasing number of neurons

Explain what happens in the divergence into multipe tracts

When the signals split and travel along different paths

What happens in the convergence of signals

- When many signals combine to afect one neuron

Name the 2 sources in convergence of signlas

- From single source -From Multiple sources

Explain what happens in convergence of signals from SINGLE SOUR

- Multiple termilas from one fiber excite a single neuron

Explain what haooens in convergence of signals from multiple sources

- Inputs from different locations meet on the same neuron

What is a reciprocal inhibiton circuit

- When some signals cause excitation in one pathway and inhibition in another at the same time

Explain the mechanism of reciprocal inhibiton circuit

An input fiber excites: An excitatory pathway directly. An inhibitory neuron, which blocks the opposite pathway using different neurotransmitters.

What is afterdischarge

- This is when even after a signal ends, some cirucits continue to fire for a short or long time

Name 2 types of afterdischarge

- Synaptic Afterdischarge -Reverberatory circuits

What is synaptic dishcage caused by

- Excitatory synapes that geneate a long lasting electrical potential

What can make the affect of synaptic discharge longer

Neurotransmitters

What is the result of synaptic afterdischarge

- A brief signal can produce sustained output

What do reverberatory circuits use + why

They use positive feedback to keep re exciting themselvs - Once started they can keep firing on their own for a while

Name the differnet types of Reverberatory circuits

- Simple loop -Delayed loop -Controlled loop -Complex loop

What do some neuronal cirucits naturally produce

rhythmic signals

Give an example of rhthmic signlas

- Respiratory centers in the medulla and pons

Some rhythmical movements need what? to start a rhythm

- An input stimulus

What are rhythmic signals usually caused by

- Reverbating circuits

Stength and speed of rhythmic signals can be modifed by what

-Excitatory or inhibioty inputs

Explain the instability risk of neuronal circuits

- As many brain areas are interconnected, theres a risk that signlas could loop endlessly - This can cause uncontrolled signal loops, leading to overload seen in epileptic seizures

What can prevent the instability of neuronal cirucits

- Stabilizing mechanisms

Name the 2 types of stabilising mechanism

- Inhibiotry circuts -Synaptic fatugue

What is inhibitroy circuts as a stabilising mechanism divided into

- Feedback inhibition -Widespread inhibition

Now explain the 2 components in inhibitory circuits as a stabilizing mechanism

Feedback inhibition: Signal returns to shut down its own pathway when activity gets too high. Widespread inhibition: Some neuron pools (like the basal ganglia) suppress activity across large brain regions to maintain balance.

Explain what happens in synaptic fatigue as a stabilising mechanism

- The more a synapse is used, the weaker it becomes temporarily. This is a self-limiting mechanism that helps stop continuous firing.

Name the 2 main ways in which Ajustments of sensitiivty in the brain is made

- Short term Fatigue mechanism -Long term receptor Regulation

Explain what happens in the short term fatigue mechanism in the adjustmnent of sensitivity in the brain

Overused circuits become less sensitive, while underused ones become more sensitive.`

Explain the 2 components in Long term Receptor regulation as part of adjustment of Sensitivity

Upregulation: If a synapse is underused, more receptors are added to increase sensitivity. Downregulation: If overused, receptors are removed to reduce sensitivity.

COM1 Physiology C47 week 2 Flashcards

(78 cards)