COM 1 Physiology Week 1 C46 Flashcards
1
Q
How do neurons recieve
signals
A
Through synapses on dendrites and the cell body
2
Q
How do ouput signals travel
A
Via a single axon
3
Q
Why does the synapses ensure one way signle transmission
A
For proper nervous system function
4
Q
What do sensory receptors detect
A
Stimuli
5
Q
What can sensory input cause
A
Immediate reactions or be stored for future responses
6
Q
Explain how sensory informaton is transmitted + examples (5)
A
To the CNS through the peripheral nerves and reaches including:
-Spinal cord
-Brainstem
-Cerebellum
-Thalamus
-Cerebral cortex
7
Q
How does the nervous system control bodily activites in the motor part
A
-By regulating :
-skeletal muscle contraction
-Smooth muscle contraction
-Glandular secretion
8
Q
What does the motor system consist of
A
- Skeletal motor nerve axis
-Autonomic nervous system
9
Q
What is the function of the skeletal motor nerve axis
A
- Controls skeletal muscles
10
Q
What is the function of the autonomic nervous system
A
- Controls smooth muscles and glands
11
Q
Name the multiple CNS levels in which motor control occurs
A
- Spinal cord
-Brainstem
-Basal ganglia
-Cerebellum
-Motor cortex
12
Q
What are synapses
A
Junctions between neurons that control signal transmission
13
Q
What do facilitatory and inhibitory signals regulate
A
Wether synapses transmit or block signals
14
Q
Explain what synapses can do to signals
A
- Block weak signals while allowing
strong ones - Amplify weak signals when necessary
- Direct signals in multiple pathways instead of just one
15
Q
What does limited immediate response mean in relation to the storag of information(Memory)
A
Means that only a small portion of sensory information leads to immediate motor responses; most is stored for future use.
16
Q
What is storage of information also known as
A
Memory
17
Q
Where are the locations of memory storgae
A
Most storage occurs in the cerebral cortex, but also in the basal brain regions and spinal cord
18
Q
What is the role of synapses in Memory
A
Memory is lonked to synaptic activity
-Repeated sensory signal transmission enhances synaps efficiency
19
Q
What happens in the facilitation process in relation to the storage of information-memory
A
- Repeated stimulation strengthens synapses, allowing memory recall even without sensory input
20
Q
Name the 3 major levels of the CNS
A
- Spinal cord level
-Lower brain(subcortical level)
-Higher brain(cortical level)
21
Q
Explain the function of spinal cord level of the CNS
A
- More than just a single conduit, it controls basic recpetors
22
Q
In the spinal cord level what can neuronal circuits cause
A
-Neuronal circuits can cause:
Walking movements
Pain withdrawal reflexes
Posture refleces
Control of blood vessels
23
Q
What is the function of the lowerbrain (subcortical levels)
A
-Controls subconscious body functions
24
Q
What does the lowerbrain( subcortical) level include(7)
A
- Includes:
- medulla, pons,mesencephalon,hypothalamus,cerebellum,thalamus, basal ganglia
25
What is the 4 key functions of the lower brain(subcortical) level
- Blood pressure and respiration
-Equillibrium control
-Feeding reflexes
-Emotional responses
26
In the lower brain level , what is blood pressure and respiration controlled by
- Medulla and pons
27
In the lower brain level what is equillibrum control , controlled by
- Cerebellum and brainstem
28
Explain the Higher brain(cortical level)
- A memory storehouse, that works with the lower brain for precise control
29
What is the function of the lower brain when working with the higher brain in the HIGHER BRAIN LEVEL
It initiates wakefulness, enabling cortical memory
30
Explain what happens in simple computers+e.g
-Output singlas are directly controlled by input signals
- Spinal cord reflexes
31
Explain what happens in complex computers
-Output signals are influenced by input signals+ stored memory
32
What type of computers reuqire a CPU( Central processing unit)
- Advanced computers
33
What is the function of CPU- Central processing Unit
- Directs sequences of operations
34
Explain how the brain is similar to a computer
- Like a computer, the brain continuosuy collects data, porcesses stored information and directs bodily activites based on both
35
Nerve impulses transmit info through what
Neurons
36
Name the 2 types of synapses
-Chemical synapses
-Eletrical synapses
37
What do chemical synapses use and how do they work
- Use neurotransmitters
-Can excite,inhibit or modify neuron sensitivity
38
What do electrical synapses use
- Gap junctiona to transfer ions directly between neurons
39
What are the 2 functions of electrical synapses
- Allow biodirectional transmission +synchronised neuronal activity
- Help detect simultaneous subthreshold depolarisations
40
What is the most common synapse in the CNS
- Chemical
41
What is the function of presynaptic neurons
Release neurotransmitters
42
What is the 3 parts of a motor neuron
- soma
- Axon
-Dendrites
43
When synaptic knobs are excitatory what do they release
Neurotransmitters that excite
44
When synaptic knobs are inhibitory they release
Neurotransmitters that inhibit
45
What can presynaptic terminals be called
- synaptic knobs
- boutons
- terminal knobs
- end feet
46
Neurons differ based one what 4 factors
- size of soma
- dendrite structure
-Axon structure
- Number of presynaptic terminals
47
What is the function of transmitter vesicles
Store neurotransmitters
48
Explain what happens to NEUROTRANSMITTERS once an action potential reaches the presynaptic terminals
- The membrane depolarises
-Vesicles releases neurotransmitters into they synaptic cleft
-Neurotransmitters bind to the postsynaptic recpetors, altering the membrane permeability
49
Name the 2 components the postsynaptic membrane has on its receptor proteins
-Binding component
-Intracellular component
50
What is the function of the binding component
-It bins neurotransmitters in the shynaptic cleft
51
What is ionotrophoic receptors + example
They are receptors that directly open ion channles when neurotransmitters bind. Direct ion gating
52
What are metabotrophic receptors
- Second messenger activation
53
Are cation channels excitatory or inhibitory
Excitatory
54
Are anion channels excitatory or inhibitory
Inhibitory
55
What do Excitatory neurotransmitters open
What do inhibitatory neurotransmitters open
- cation channels
-Anion channels
56
Name a type of second messenger mechanism
G protein system
57
In the inactive state explain what happens to the G protein
- The G protein is bound to GDP
58
Explain what happens in the G protein during activation
A neurotransmitter binds, casuing the G protein to bind to GTP
59
What are the 4 functions of G proteins
- Open specific ion channels
-Activates cAMP,cGMP
-Activates intracellular encyems
-Triggers gene transcription
60
How is the G protein brough back to its inactivate state starting from GTP
-GTP is hydrolysed back to GDP, restoring the G protein
61
Name 3 types of synaptic Transmitters
- small molecule transmitters
- Neuropeptides
- Gaseous molecules
62
What are neuropeptides
- Larger molecules that cause prolonged effects, such as long term chnages in synapses
63
What can gaseous molecules act as
- Modulators
64
Which type of synaptic neurotransmitter is not confirmed as a true neurotransmitter
Gaseous molecules
65
Where are small molecules, rapidly acting transmitters synthesized
In the cytosol of presynaptic terminals
66
Where are small molecule rapidly actig transmitters stored and released
Vesicles
released in synaptic cleft
67
If the small molecule rapidly acting transmitters are excitatory, what is the effect
Increase sodium conductance
68
If the small molecule rapidly acting transmitters are Inhibitory, what is the effect
Increases potassium or chloride conductance
69
Explain the process of vesicle recyling after neurotransmitters are released
-The vesicle membranes merge with synaptic membranes
-Vesicles are then reformed and refilled with neurotransmitters
70
What is acteylcholine synthesized from
- AcetylcoA and chlorine via chlorine acetyltransferase
71
Give an example of a small molecule rapidly acting transmitter
Acetylcholine
72
Name 6 small molecule transmitters
- Acetylcholine
-Norepinephrine
-Dopamine
-Glycine
-GABA
Glutamate
73
What is Acetylcholine secreted by
neurons in the motor cortex, basal ganglia, skeletal muscles and autonomic systek
74
Name 3 gaseous molecule transmitter
- Nitric Oxide
-Carbon monoxide
-Hydrogen Sulfide
75
Where are neuropeptides processed
-Golgi
76
Where are neuropeptides synthesized
- Cell body
77
What type of synapse transmitter is more potent than small molecule transmitters
Neuropeptides
78
What is the resting membrane potential of a spinal motor neuron
- 65mv
79
Is the RMP value in a spinal motor nere more negative or less negative than in peripheral berve fibers
Less negative
80
Across neuronal membranes, Where is Na high and low + reason
High outside, low inside, actively pumped out
81
Across neuronal membranes, where is K high and low + reason
- High inside, low outside,
actively pumped in
82
Across neuronal membranes, where is Cl high and low
- High outside, low inside
83
Explain the concept of EPSP(excitatory postsynaptic potential)
- When an excitatory neurotransmiiter is released, it increases Na+ permeability,
the Na+ influx reduces geativity, increasing the potential
84
What do neurons recieve more of in an inhibitory state
They recieve more inhibitory than excitatory input
85
86
What do inhibitory synapes open
Chloride or K channels
87
Explain the process of IPSP(Inhibitory Postsynaptic potential)
-Starting w inhibitory synapses
- Inhibitory synapesopen k or chloride channels
- Chloride influx makes the inside of the neuron more negative
-The hyperpolarization inhibits the neuron, making it less likely to fire an action potential
-The increases in negativity is called an IPSP
88
When does the presynaptic inhibition occur
- Before the signal reaches the synapses
89
What is the main inhibitory neurotransmitter
-GABA
90
Explain what channel GABA opens and the effect
Gaba opens chlorine channels, allowing chlorine to nter the presynaptic terminals, reducing excitation
-This cancels out Na
91
What do excitatory synapses create
EPSP
92
What does inhibitory synapses create
IPSP
93
Explain what happens in spatial summation
- When multiple presynaptic terminals, firing simulatenously add together and and summate their effects
- EPSPs from different locations add together,
-When the combined ESPS reach the threshold an action potential is trigered
94
What happens when neurons are facilitated
- They are now closer to firing and can be asily excited by another small excitatory signal
94
What is the function of diffuse facilitation in the nervous system
-They make groups of neurons more responsive to future signals
95
What happens when an EPSP(excitatory) and IPSP(inhibitory) occur at the same time
-They can partially or fully cancel each other out
96
Explain what happens in temporal summation
When a single presynaptic terminal ,
fires multiple action potentials rapidly
-If the terminal fires again before the EPSP fades the singlas are added together increasing the potential
97
Why cant dendrites transmit action potentials
- Because they have few voltage-gated sodium channels
98
How do dendrites transmit singlas
By electrotonic conduction
99
Why are dendrites leaky
- Due to their permeabiity to potassium and chloride ions, causing signal loss before reaching the soma
100
Do the synapses near the soma have stronger or weaker effects on excitation and inhibition
They have stronger effects
101
Why are inhibioty synapses near the soma effective
- Because they can get rid of the signals before they reach the neuron
102
Is inhibition at the axon hillock strong or weak
stronger
104
What do the neurons recieve more of in the excitatory state
They receive more excitatory than inhibitory input
105
What happens t
106
What do the neurons recieve when in an inhibitory state
They recieve more inhibitory than excitatory input
107
What are the causes of fatigue
-Depletion of neurotransmitters in presynaptic terminal
-Inactivation of post synaptic receptors
-Abnormal ion concentrations inside the neuron
108
What is the effect of alkalosis in synaptic transmission and what it can trigger
It increases neuron excitability . Can trigger epileptic seizures
109
What is the effect of acidosis on synaptic transmission
Depressed neuronal activity , can lead to a coma
110
What is the effect of stimulants such as :Caffeine, Theophylline,Theobromine
They increase neuronal excitability by lowering the excitation threshold
111
What is the effect of strychnine in synaptic transmission
Blocks inhibitory neurotransmitters , leading to excessive firing and muscle spasms
112
What is the effect of Anesthetics on synaptic transmission
Increases the excitation threshold , reducing synaptic transmission and causing sedation
113
What molecule is essential for neuronal excitability
Oxygen
114
Explain the relationship between Action potential frequency and receptor potential
Action potential frequency increases porportionally to receptor potential but plateus at extreme stimulus intensities
115
What is the importance of the mechanism where action potential frequencys plateu at extreme intensities
-Allows recpeotrs to detect both weak and intense stimulo
