U3AOS1A - Nervous System Functioning Flashcards
Cambridge 3B-C
1
Q
Define nervous system
A
- Complex, highly organised network of specialised cells that enable the brain to perceive internal & external information as well as respond appropriately
2
Q
What is a neural pathway?
A
- A chain of neurons that connect one part of the nervous system to another
3
Q
What does the central nervous system consist of?
A
- Brain
- Spinal CORD
4
Q
What is the function of the CNS?
A
- Receives sensory information from the PNS
- Sends motor information to the PNS
5
Q
Describe the role of the brain in the nervous system
A
- Regulates and guides all other parts of the NS
- Responsible for…
- Vital bodily functions like breathing, heart rate and digestion
- Receiving information from the outside world via the senses and coordinating appropriate responses
- Higher order functions like planning, thinking and learning
- Emotions, personalities, sense of humour
6
Q
Describe the role of the spinal cord in the nervous system
A
- Cable-like column of nerve fibres that extends from the base of the brain to the lower back and is encased by a series of bones called vertebrae
- Helps brings sensory messages to the brain
- Takes motor messsages back
7
Q
Describe with keywords how the spinal cord helps the brain communicate
SAME (acronym)
A
- Two-direction highway
- Sends sensory messages towards the brain through afferent tracts
- Sends motor messages away from the brain through efferent tracts
- Designed this way for speed
- Exception of spinal cord reflex
8
Q
What would injury to the spinal cord cause?
A
- Brain losing sensory information and control over the body
- Severity depends on…
- Where the spinal cord is injured
- Extent of injury
- Generally, the higher up on the spine the injury is, the greater number of connections are disturbed
9
Q
What does the peripheral nervous system consist of?
MOG
A
- Everything outside the brain and spinal cord
- Muscles, Organs and Glands
10
Q
Why aren’t interneurons present in the PNS?
A
- Interneurons are only in the spinal cord
- The spinal is not part of the PNS
11
Q
What is the function of the PNS?
A
- Sends sensory information to the CNS
- Recieves motor information from the CNS
12
Q
What is the PNS broken down into?
A
-
Somatic NS
- Information to skeletal muscles to initiate voluntary movement
- Sensory information to CNS based on 5 senses
-
Autonomic NS
- Between CNS and organs and glands to ensure they are regulated without conscious awareness
13
Q
Why is the autonomic NS referred to as autonomous? Is this accurate?
A
- Most aspects of it are self regulating and occur without conscious effort
-
Not an accurate description because some parts of the ANS we can consciously control
- For example blinking and breathing because it is linked to the cerebral cortex
14
Q
When can you become consciously aware of ANS functions?
A
- In intense situations (can be good or bad)
- For example getting into your dream university or getting up to do an oral presentation
15
Q
What are the subdivisions of the autonomic nervous system?
A
-
Sympathetic NS
- Prepares the body for action, to deal with a potential threat
- Activates the fight-flight-freeze response
-
Parasympathetic NS
- Maintains the body in a state of homeostasis
- Returns body to state of calm following stress or heightened arousal
- Counterbalances sympathetic
-
Enteric
- Embedded within the walls of the gastrointestinal (digestive) tract
- Extensive two-way connections with the CNS
- Can function independently of the brain and carry out its functions without communicating with the brain
- Contains living organisms called gut microbiota that maintain gut health and functioning
16
Q
Name 4 examples of responses by the sympathetic NS to a threat
A
-
Pupils dilating
- Allows more light into the eye to see better
-
Heart rate, blood pressure and breathing rates increasing
- Accelerates oxygenated blood flow to the muscles
- Energy being diverted to muscles from functions such as digestion
- Conserves energy for responding to the threat
- Increased sugar and fat being released into the blood
- Provide energy
17
Q
Why is the sympathetic nervous system dominant in the face of a threat?
A
- Main function is to increase arousal
- Readies body for a quick response (FFF response)
18
Q
How do the sympathetic and parasympathetic NS function?
A
- The sympathetic and parasympathetic nervous systems do not function in an ‘on/off’ or ‘either/or’ way
- They are both active at the same time but one tends to be dominant over the other
- Parasympathetic NS dominates during normal day-to-day activities
19
Q
How do the enteric nervous system and the central nervous system interact?
A
- Two-way; Independent and interdependent
- The ENS and CNS communicate in order to manage your wellbeing and control your digestive system
- ENS controls 90% of bodys serotonin
20
Q
Why is there a difference in speed between the sympathetic and parasympathetic NS?
A
- Sympathetic reaction is immediate
- Your body takes longer to return to a state of calm (parasympathetic) because sympathetic hormones linger within the bloodstream for some time after the threat has passed
21
Q
Compare the sympathetic and parasympathetic nervous system
A
- SNS - Dilates pupils, PNS - Contracts pupils
- SNS - Accelerates heartbeat, PNS - Slows heartbeat
- SNS - Inhibits digestion, PNS - Stimulates digestion
- SNS - Stimulates glucose release by liver, PNS - Stimulates gallbladder
- SNS - Secretion of epinephrine and norepinephrine
- SNS - Contracts bladder, PNS - Relaxes bladder
- TLDR - SNS Activates functions in order to prepare for a threat; in order to do this, bodily functions that are not readily needed are surpressed
- PNS Returns the body to it’s natural state of equilibrium (homeostasis)
22
Q
Distinguish between conscious and unconscious responses
A
- You are aware of conscious responses - Unaware of unconscious
- Able to control conscious responses - Unable to control unconscious
- Conscious responses are voluntary - Unconscious are involuntary
- CR can involve learning - UR generally dont
- CR are more complex, series of responses - UR simpler, single response
23
Q
What is the fight-flight-freeze response?
A
- Initiated by sympathetic
- Prepares the body to confront a stressful situation to optimise the chance of survival
- Adaptive response (beneficial for survival)
- The mechanism adopted is dependent on the likelihood of survival in each situation
- Fight - Stay and Attack
- Flight - Run
- Freeze - Go unnoticed or undetected/ assess situation → Immobility, high arousal, alertness and tension (parasympathetic dominant)
24
Q
What are adaptive changes that occur when the fight-flight-freeze response is activated?
A
- Increased heart rate, breathing rate, blood pressure
- Provides muscles with oxygenated blood
-
Dilated pupils
- Increases light into eyes and therefore aids vision
- Increased sweat production
- Cools down body
25
Q
What is a spinal reflex/reflex arc?
A
- Automatic, unconscious response that is initiated by neurons in the spinal cord
- Independent of the brain
- Occurs in moments of physical pain and aids survival
- Message intercepted by interneurons in spinal cord
26
Q
What are the steps of a spinal reflex?
A
- Sensory stimulus detected by sensory receptors
- Sensory neurons transmit sensory information towards the spinal cord (Afferent)
- Sensory information relayed to interneurons
- Interneurons connect motor and sensory neurons by relaying information
- Adaptive involuntary motor response is initiated by the interneurons without input from the brain
- Motor movement information relayed to motor neurons - Transmit information to relevant muscles (Efferent)
- Muscles are activated to perform movements required (still without input from the brain)
27
Q
Why is a spinal reflex adaptive?
A
- Response is conducted before it is consciously interpreted by the brain, ensuring efficiency → Maximises chance that one does not get injured
- Although this is only by a fraction of a second, this time could mean the difference between life and death
28
Q
Define neuron
A
- Building blocks of the nervous system
- Transmit messages to and from the brain, various functions
- Look different depending on function
29
Q
Describe the 3 main types of neurons
A
-
Sensory Neuron (Afferent)
- Cell body is in the middle and sticks out of axons
- Transmit sensory information from body to brain
-
Motor Neuron (Efferent)
- Generic shape (shaped like an i)
- Transmit information from brain to body
-
Interneuron
- Cell body is in the middle, axons start from below
- Transmit information between sensory and motor
- Most abundant in the brain
- Not present in peripheral NS
30
Q
Draw and label a neuron
A
- Should include…
- Soma (cell body) with nucleus
- Dendrites - Recieves incoming neural messages
- Dendritic spines
- Axon - Pathway that neural message travles
- Myelin Sheath - Fatty tissue that encases axon to aid speed of transmission
- Direction of impulse
- Axon Terminals - Exit pathways for neural messages to make way to the next neuron
- Terminal Buttons - Releases chemical substance known as a neurotransmitter to a recieving neuron
31
Q
Outline the steps of neurotransmission
A
- Neural impulse/ action potential (electrical) runs from dendrite to the axon and axon terminals in presynaptic neuron
- Terminal buttons release neurotransmitter
- Neurotransmitter crosses the synapse (space between neurons)
- Neurotransmitter picked up by postsynaptic neuron
Uses electrochemical energy
32
Q
Describe neurotransmission in terms of the synapse
A
- Neurotransmitters stored in synaptic vesicles
- When stimulated, the pre synaptic neuron releases neurotransmitters across the synapse
- Specific receptor site on the post synaptic neuron recieves the neurotransmitter
- Any neurotransmitter molecules that are not recieved are taken back into the presynaptic neuron through reuptake
33
Q
Define neurotransmitter
A
- Chemical substance released by the terminal button of a neuron
- Necessary for neural communication
34
Q
What is an excitatory neurotransmitter?
A
- Increases the likelihood that the neuron will fire an action potential
- E.g Glutamate - Helps with formation and retrieval of a memory and therefore learning + habits
- Too much - Migraines due to overstimulation of neurons
- Too little - Poor communication between neurons
35
Q
What is an inhibitory neurotransmitter?
A
- Decreases the likelihood that the neuron will fire an action potential
- E.g Gamma-amino butyric acid (GABA) - Associated with calming feelings of anxiety, stress or fear
- Too much - Sluggish, foggy thinking
- Too little - Postsynaptic neurons can get out of control, anxiety
36
Q
What is a neuromodulator?
A
- Chemical messenger that enhances signal transmission
- Work together with neurotransmitters to enhance the inhibitory and excitatory effects and create more widespread impacts
- Effective on a group of neurons and impacts last longer
- Released in same way as neurotransmitters
37
Q
Describe dopamine
A
- Neuromodulator that is involved in drive, motivation and motor movement
- Associated with addictive behaviours such as gambling
- Associated with the effectiveness of ‘to-do lists’
- Too much - Hallucinations and delusions
- Too little - Lack of motivation to complete mundane activities
🔗- Learning and Memory
38
Q
Describe serotonin
A
- Neuromodulator involved in mood stabilisation
- Plays important role in wellbeing and happiness
- Important in digestion and metabolism as well as stress
- Too much - Serotonin syndrome
- Too little - Anxiety disorders
🔗- Gut-brain axis, stress, sleep-wake cycle
39
Q
Distinguish between neurotransmitters and neuromodulators
A
- Modulators can affect multiple synapses
- Modulators tend to be slower acting
- Modulators can influence effects of neurotransmitters (alter receptor)
40
Q
What is neuroplasticity?
A
- The ability of the brain to physically change in response to experience
- Two types - Developmental and Adaptive
41
Q
What is developmental plasticity?
A
- Occurs naturally across the lifespan
- Certain critical periods that enable greater developmental plasticity
42
Q
What is adaptive plasticity?
A
- Occurs as a result of brain damage or trauma
- Utilising critical periods for developmental plasticity helps enable greater adaptive plasticity
43
Q
What is Hebb’s rule?
A
- ‘Neurons that fire together, wire together’
- Neurons that continuously interact with each other will form a strong synaptic bond
44
Q
What is long-term potentiation?
A
- Long-lasting and experience-dependent strengthening of synaptic connections that are regularly activated
45
Q
What is long-term depression?
A
- Long-lasting and experience-dependent weakening of synaptic connections between neurons that are not regularly activated
46
Q
What are the processes that neurons go through?
A
-
Proliferation
- Mass creation of neurons from birth
-
Migration
- Neurons migrate to areas that they are needed
-
Circuit Formation
- Creation of synapses
- Strong = Proceed to Myelination (strengthen)
-
Circuit Pruning
- Removing neural connections
47
Q
What are the 3 specific neural processes involved in synaptic plasticity?
SRP
A
-
Sprouting - The ability of dendrites or axons to change over time in response to activity or experience
- Become ‘bushier’
- Rerouting - The ability of a neuron that is connected to a damaged neuron to create an alternate synaptic connection
- Pruning - The elimination of synaptic connections that are not adequately activated
48
Q
What are two synaptic modifications that occur during sprouting?
A
-
Dendritic Branching
- Bushier dendrites on the postsynaptic neuron
-
Filigree Appendages
- Growth of the axon terminal on the presynaptic neuron
