COM1 Physiology C47 week 2 Flashcards
(78 cards)
1
Q
Name the 5 basic types of sensory receptors
A
- Mechanoreceptors
-Thermoreceptors
-Nociceptors
-Electromagnetic receptors
-Chemoreceptors
2
Q
What do mechanorecpetors detect
A
- Mechanical compression or stretching
3
Q
What do thermorecpetors detect
A
- Detect temperature changes
4
Q
What do nociceptors detect
A
- Pain from physical or chemical damage
5
Q
What do electormagnetic receptors detect
A
- Detect light in the retina
6
Q
What do chemoreceptors detect
A
Taste,smell,blood oxygen levels,osmolality+ chemical composition
7
Q
Explain the differential sensitivity of receptors
A
- Each receptor is highly sensitive to its specific stimulus and unresponsive to other types
8
Q
What is each type of sensation called
A
Modaliity
9
Q
Do all nerve fibers transmit the same kind of impulses
A
Yes
10
Q
What does the percieved sensation depend on
A
Where the fiber terminates in the brain
11
Q
What is the receptor potential
A
Change in potential
12
Q
What do receptor potentials initiate when they exceed the threshold
A
Initiate a nerve
13
Q
Name the 4 mechanisms that can excite sensory receptors
A
- Mechanical deformation
- Chemical activation
-Temperature changes - Electromagnetic radiation
14
Q
Explain how mechanical deformation excites sensory receptors
A
- By Streching opens ion channels
15
Q
Explain how chemical activation excites sensory receptors
A
-The binding of molecules opens ion channels
16
Q
Explain how temperature changes excite snesory receptors
A
Alter membrane permeability
17
Q
Explain how electromagnetic radiation excites sensory receptors
A
The light alters retinal receptor proteins
18
Q
What does a greater receptor potential lead to
A
Higher frequency of action potentials which lead to sensory signals
19
Q
What does pacinian corpuscle contain
A
Central nerve fibre surrounded by multiple capsule layers
20
Q
What is the effect of compression of the Pacinian corpuscle
A
Compression of the corpuscle deforms the central fibre, triggering receptor activity
21
Q
Is the tip of the pacinian corpuscle myelinated or unnyelinated
A
Unmyelinated
22
Q
When does the tip of the fiber of the pacinian corpuscle become myelinated
A
Before entering the peripheral sensory nerve
23
Q
Explain the mechanism of receptor potential generation (how it’s generated) in Pacinian corpuscle
A
- 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
24
Q
Explain the relationship between stimuli and receptor potential
A
Strong stimuli means higher receptor potential generation
25
Explain the responses of snesory receptors to stimuli
- Initially they respond strongly, but the response gradually decreases or stops
26
Name 3 mechanims by which receptors adapt
- Rapid Adapting receptors
- Slow adapting receptors
-Non adapting receptors
27
# 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.
28
What is the basic function of Rapid adapting receptors
- Stop responding quickly
29
What is the basic function of slow adapting receptors
- They continue responding for longer periods
30
Explain the basic function of non adapting receptors
They do not fully adapt as their function is crucial for survival
31
Give an example of rapid adapting receptors
Pacinian corpuscles
32
Give an example of slow adapting receptors
muscle spindle
33
Name 2 mechanisms of Adaptation
- Mechanical adjustment
-Electrical Adjustment
34
Explain what happens in mechanical adjustment
- Structural changes in receptors
35
Explain what happens in Electrical accommodation
- Sodium channels in nerve fibers gradually inactivate, reducing signal transmission
36
Explain how tonic(slow) adapting receptors act in relation to a stimulus
- Continuosuly transmit signals as long as stimulus is present
37
What is th eimportance of Slow/Tonic Adapting recepots
- Help mainyain awareness of body position and funcrion
38
Explain how rapid/phase adapting receptors act in relation to stimulis
- Respond only when stimulatus strength changes
39
Explain the importance of Phas/ Rapid acting receptors
- Detect motion and rate of chnage , not constant stimuli
40
Give 2 examples of neuronal pools
-Cerebral cortex
-basal ganglia
41
Explain how neurons sends signals
The input fibers branch out sending mini signals to many neurons in the pool
42
Explain what is a suprathreshold stimulus
- If the stimulus is string enough it causes a neuron to fire
43
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)
44
Name the 3 different zones in the neuronal pool
- Discharge zone
-Facilitated zone
-Inhibitory zone
45
What happens in the dischage zone in the neuronal pool
- The area where neurons are stringly excited
46
What happens in the Facilitated zone in the neuronal pool
Where neurons are helped but not excited to the threshold
47
What is the inhibitory zone in the neuronal pool
- Where certain fibers ihibit rather than excite neurons
48
What does divergence of signals mean
- When 1 message spreads to many neurons
49
Name the 2 types of divergence
- Amplifying divergence
-Divergence into Multiple tracts
50
Explain what happens in Amlifying divergwnce
The signal spreads to an increasing number of neurons
51
Explain what happens in the divergence into multipe tracts
When the signals split and travel along different paths
52
What happens in the convergence of signals
- When many signals combine to afect one neuron
53
Name the 2 sources in convergence of signlas
- From single source
-From Multiple sources
54
Explain what happens in convergence of signals from SINGLE SOUR
- Multiple termilas from one fiber excite a single neuron
55
Explain what haooens in convergence of signals from multiple sources
- Inputs from different locations meet on the same neuron
56
What is a reciprocal inhibiton circuit
- When some signals cause excitation in one pathway and inhibition in another at the same time
57
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.
58
What is afterdischarge
- This is when even after a signal ends, some cirucits continue to fire for a short or long time
59
Name 2 types of afterdischarge
- Synaptic Afterdischarge
-Reverberatory circuits
60
What is synaptic dishcage caused by
- Excitatory synapes that geneate a long lasting electrical potential
61
What can make the affect of synaptic discharge longer
Neurotransmitters
62
What is the result of synaptic afterdischarge
- A brief signal can produce sustained output
63
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
64
Name the differnet types of Reverberatory circuits
- Simple loop
-Delayed loop
-Controlled loop
-Complex loop
65
What do some neuronal cirucits naturally produce
rhythmic signals
66
Give an example of rhthmic signlas
- Respiratory centers in the medulla and pons
67
Some rhythmical movements need what? to start a rhythm
- An input stimulus
68
What are rhythmic signals usually caused by
- Reverbating circuits
69
Stength and speed of rhythmic signals can be modifed by what
-Excitatory or inhibioty inputs
70
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
71
What can prevent the instability of neuronal cirucits
- Stabilizing mechanisms
72
Name the 2 types of stabilising mechanism
- Inhibiotry circuts
-Synaptic fatugue
73
What is inhibitroy circuts as a stabilising mechanism divided into
- Feedback inhibition
-Widespread inhibition
74
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.
75
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.
76
Name the 2 main ways in which Ajustments of sensitiivty in the brain is made
- Short term Fatigue mechanism
-Long term receptor Regulation
77
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.`
78
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.
