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Psychology U3/4 > Chapter 2: Nervous System > Flashcards

Chapter 2: Nervous System Flashcards

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1
Q

Nervous system

A
  • An organised and complex network of specialised cells
  • Receives, processes and coordinates responses to information from internal and external environments
  • Divided into the central and peripheral nervous system
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2
Q

Central nervous system (CNS)

A
  • Includes the brain and spinal cord
  • Receives and processes sensory information (from the PNS) about the body’s internal and external environments, then coordinates a response
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3
Q

Brain

A
  • Coordinates all of the body’s conscious and unconscious activities
  • “Control centre” of the nervous system
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4
Q

Conscious and unconscious responses

A
  • Conscious – involve awareness
    • Voluntary, intentional, purposeful, goal directed
    • E.g. choosing to wear glasses when the sun is out
  • Unconscious – do not involve awareness
    • Involuntary, unintentional, automatic
    • E.g. blinking or breathing
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5
Q

Spinal cord

A
  • Bundle of nerve tissue that connects the brain to the rest of the body via the peripheral NS
  • Its different tracts increase speed and efficiency
  • Damage can cause paralysis as messages cannot be conveyed for movement to occur
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6
Q

Two main functions of the spinal cord

A
  • Transmit S info from body to brain for processing
    • E.g. pain of a sprained wrist is carried from the wrist to the brain for the processing of this sensory info
  • Transmit M info from brain to body to control muscles, glands and organs so that action can be taken
    • E.g. to pick up a bottle, neural messages are sent from primary motor cortex to hand & arm muscles
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7
Q

Affarent vs efferent information

A
  • Afferent – sensory information coming into the CNS
    • Ascending tract
  • Efferent – motor information leaving the CNS
    • Descending tract

SAME: sensory = affarent, motor = efferent.

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8
Q

Peripheral nervous system (PNS)

A
  • The entire network of nerves located outside the CNS
  • Divided into the somatic and autonomic NS
  • Carries sensory information to the CNS
  • Caries motor information to muscles, organs and glands
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9
Q

Somatic nervous system (SNS)

A
  • A subdivision of the PNS
  • Controls voluntary behaviour e.g. talking and chewing
  • Involved in all skeletal muscle activities
  • Has sensory and motor function

NOTE: The SNS controls voluntary behaviour with the exception of the involuntary spinal reflex.

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10
Q

Sensory and motor function of the SNS

A
  • Sending sensory signals from S receptors to brain
    • E.g. after touching a hot surface, sensory neurons send the info to the CNS, allowing the brain to perceive the sensation of heat and pain
  • Sending motor signals from brain to skeletal muscles
    • E.g. motor neurons send the information to skeletal muscles, enabling withdrawal of the hand
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11
Q

The autonomic nervous system (ANS)

A
  • A subdivision of the PNS
  • Controls involuntary behaviour e.g. digestion
  • Involved in activity of visceral muscles, organs & glands
  • Divided into sympathetic, parasympathetic and enteric NS

NOTE: The ANS is not completely self-regulating.

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12
Q

Visceral muscles

A
  • Involved in the activity of internal organs and glands
  • Do not depend on voluntary control from the brain
  • Allow the ANS to function continuously whether awake, asleep, under anaesthetic or comatose
  • Keep vital organs + systems functioning; maintains survival
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13
Q

Why the autonomic nervous system is described as “autonomous”

A
  • Many organs, glands and processes under its control are self-regulating and, thus, occur w/o conscious effort
  • E.g. breathing & digestion occur w/o conscious awareness
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14
Q

Sympathetic nervous system

A
  • Increases activity of internal M, O & G
  • Prepares the body for action or a perceived threat by increasing alertness, energy levels, and physical readiness

NOTE: The sympathetic nervous system is often referred to as the “fight or flight” response.

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15
Q

How the SNS prepares the body for action

A
  • ↑ HR and BP – provides muscles with more oxygenated blood enabling quicker movements
  • Dilated pupils – ↑ light enters 👁, enabling clearer vision
  • Decreased salivation – inhibits digestion
  • Increased sweating – cools the body down
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16
Q

Parasympathetic nervous system

A
  • Decreases the activity of internal M, O & G
  • Helps maintain stable internal enviro (homeostasis)
  • Without it, heart rate / blood pressure would be consistently high, increasing the risk of heart attacks
  • Its key characteristics include:
    • Decreased heart rate and blood pressure
    • Constriction of pupils and airways
    • Increased salivation for digestion

NOTE: The parasympathetic system takes longer to return the body to its homeostatic state compared to the sympathetic system’s immediate activation. This is due to the longer time it takes to rid of stress hormones.

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17
Q

Enteric nervous system

A
  • Dedicated to the gastrointestinal tract
  • Includes the oesophagus, intestines and stomach
  • Can function independent of the brain
  • Communicates with the brain via the vagus nerve
  • Gut is responsible for over 80% of serotonin production
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18
Q

Ganglia

A
  • Neurons that are grouped together in clusters in the enteric nervous system
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19
Q

Distinguish between the role of the SNS and the ANS

A
  • Both involve muscles
  • SNS initates skeletal muscle movement, whilst the ANS regulates activity of the visceral M, O & G

NOTE: When asked to compare, always use comparative statements (e.g. whilst, whereas & on the other hand).

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20
Q

Distinguish between the sympathetic and parasympathetic NS

A
  • Both are subdivisions of the ANS
  • Both involve the activity of visceral muscles
  • The sympathetic NS prepares to body for action whilst the parasympathetic nervous system calms the body

NOTE: When one is active, it does not mean that the other is inactive. Rather, one is dominant over the other at any given time depending on the situation.

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21
Q

Differences between the sympathetic NS response and spinal reflex

A
  • The sympathetic NS initiates change in visceral M, O & G whilst the SR initiates change in skeletal muscles
  • The sympathetic NS is controlled by the autonomic NS whilst the SR is controlled by the somatic NS
22
Q

Spinal reflex

‘Reflex arc’

A
  • Unconscious, automatic response that is mediated by the spinal cord (does not involve the brain)
  • Rapid process that can serve as a safety net in the case of brain injury / dynsfunction which promotes survival

NOTE: The spinal reflex is governed by the SNS. It is the involuntary exception to the voluntary SNS.

23
Q

Spinal reflex as an adaptive response

A
  • It is an immediate response by the SC that doesn’t depend on the brain, enabling a fast reaction time
  • Saving time in harmful situations enhances survival
24
Q

Spinal reflex with reference to touching a hot pan

A
  • Receptor cells in the skin detect the heat and send a neural mesage to sensory neurons
  • Sensory neurons carry the message along an affarent pathway to the spinal cord
  • Interneurons in SC relay the message to motor N
  • Motor neurons carry the message along an efferent pathway to hand muscles causing a withdrawal reflex (hand releases the pan)
  • While the reflex occurs, the message is carried up to brain
  • Brain receives the message, allowing it to perceive the sensation of heat and pain

NOTE: The brain perceives the sensation of heat and pain only after the spinal reflex has occured.

25
Q

3 types of neurons

A
  • Sensory
    • Afferent (PNS → CNS); found in the PNS
    • Carry sensory info from receptor sites interneurons
  • Interneurons
    • Only found in the CNS
    • The most numerous type of neuron
    • Receive sensory info from afferent neurons and send motor responses to efferent neurons
  • Motor
    • Efferent (CNS → PNS); found in the PNS
    • Carry motor info from CNS to visceral M, O & G
26
Q

Neurotransmitters

A
  • Chemical substances produced by neurons to communicate with other neurons
  • Bind to receptors on postsynaptic neurons that are specialised to receive that specific neurotransmitter
  • Either has an excitatory or inhibitory effect
27
Q

Excitatory vs inhibitory effects

A
  • Excitatory – stimulate / activate postsynaptic N
    • Activate neural pathways in brain
    • Allow us to take action
    • Too many can lead to overstimulation, neural damage, muscle tremors, and anxiety
  • Inhibitory – prevent postsynaptic N from firing
    • Counterbalance excitatory effects
    • Allow us to remain calm
    • Ensure that only relevant neurons are activated
    • ↓ arousal & muscular movements as appropriate
  • Whether a NT is excitatory/inhibitory depends on the receptor’s properties and location in the brain

NOTE: Do not use the words “excite” or “inhibit” when describing the excitatory and inhibitory effects of neurotransmitters.

28
Q

Synapse

A
  • The site where adjacent neurons communicate by transmitting neural signals to one another
  • Made up of:
    • The synpatic gap/cleft
    • Terminal buttons of the presynaptic neuron
    • Dendrites of the postsynaptic neuron
29
Q

Synaptic transmission

A
  • Action potential fires down presynaptic N axon
    • Initiated by excitatory NTs from presynaptic neurons
    • Inside a neuron, –vely charged ions become +ve
    • Outside a neuron, +vely charged ions become –ve
  • Neurotransmitters are released
    • Electrical signals are converted into chemical signals
    • Presynaptic terminal buttons release NTs (from vesicles)
  • NTs bind to post-synaptic neuron
    • NTs cross the synaptic gap and bind to postsynaptic dendrites with complementary binding sites
    • NTs that do not bind are recycled via reuptake or are digested by enzymes
  • Excitatory and inhibitory effects
    • If more NTs are excitatory, AP will be generated and will continue down the postsynaptic neuron
    • If more NTs are inhibitory, AP is less likely to be generated and the message will not continue
30
Q

Communication within and between neurons

A
  • Communication within = electrical (action potentials)
  • Communication between = chemical (neurotransmitters)
31
Q

Glutamate (Glu)

A
  • Excitatory (2nd most abundant NT in the brain)
  • Role in learning, memory, perception, thinking, movement
  • Promotes growth & strengthening of synaptic connections
  • Abnormally high levels of glu overstimulates neurons resulting in neural damage, seizures, epilepsy or anxiety
  • Low levels associated with learning / memory issues, low concentration and low energy
  • Realeased in more than 90% of synapses

TIP: Glu(cose) provides energy = excitatory.

32
Q

Gamma-amino butyric acid (GABA)

A
  • Inhibitory
  • Fine-tunes neurotransmission for optimal functioning
  • Counterbalances glutamate’s excitatory effects
  • Prevents uncontrolled activation of neurons
  • ↓ levels is associated w seziures, anxiety & depression
33
Q

Neuromodulators

A
  • A subset of neurotransmitters
  • Modulate / influence the effects of other NTs
  • Can change the reactivity of receptors to enhance the excitatory or inhibitory effects of NTs
  • Can work with another NT to make it more or less potent
  • Released into broad areas (not a single synapse) and can, thus, influence multiple neurons / brain areas / pathways
34
Q

Neurotransmitters vs neuromodulators

A
  • NTs are released into a single synapse while NMs can affect multiple synapses simultaneously
  • NTs work quickly and have rapid effects on postsynaptic neurons while NMs have slower and more prolonged effects
  • Both are chemical signals that are released by neurons
35
Q

Dopamine

A
  • Excitatory / inhibitory neuromodulator (mainly E)
  • Involved in voluntary movement, pleasure, motivation, appetite, reward-based learning and memory
  • Works in nigrostriatal or mesolimbic/mesocortical pathway
36
Q

Excitatory or inhibitory effects of dopamine

A
  • Depends on its location & type of receptors present
  • Excitatory fx cause us to seek activities that bring pleasure
  • Inhibitory fx reduce impulse control and rational thinking
37
Q

Nigrostriatal pathway

A
  • Enables smooth, coordinated function of the body’s muscles and movements
  • Dopamine is released in the substantia nigra
  • Damage to SN ↓ dopamine available in pathway resulting in coordination & motor activity issues (e.g. Parkinson’s)

NOTE: Parkinson’s disease is a neurodegenerative disorder that primarily affects movement. Its common symptoms include tremors, muscle stiffness and slowed movements.

38
Q

Mesolimbic and mesocortical pathway

A
  • Overlap and form the dopamine reward system
  • Dopamine is released in the the ventral tegmental
  • Dop brings feelings of pleasure (associated w addiction)
  • Excessive dopamine in this pathway is associated with hallucinations and delusions (symptoms of Schizophrenia)
39
Q

Explain how dopamine released in the mesolimbic pathway can lead to addiction

A
  • Dop released after experiencing stimulus (e.g. gambling)
  • Dop results in feelings of satisfaction and pleasure
  • Memory regions of the brain remember the pleasant exp resulting in the repetition of behaviour (addiction)
40
Q

Serotonin

A
  • Inhibitory NM (can be excitatory)
  • Helps counterbalance excitatory effects of other NTs
  • Involved in the sleep–wake cycle, mood, emotional processing, appetite and pain perception

NOTE: The majority of serotonin is found in the enteric nervous system within the gastrointestinal tract.

41
Q

Serotonin’s implications

A
  • Low levels:
    • Mood & anxiety disorders (e.g. depression & OCD)
    • Insomnia or disrupted sleep
    • ↓ feelings of reward from pleasant experiences
  • High levels:
    • Serotonin syndrome (fever, restlessness, agitation, hallucinations, seizures)

NOTE: Depression and anxiety medication increase serotonin levels.

42
Q

Synaptic plasticity

A
  • Ability of synapses to change in resp to experience
  • Involves strengthening & weakening of neural connections
  • Enables efficient and effective functioning of the NS
  • The biological foundation for learning and memory

NOTE: Learning and memory are interdependent / bidirectional. If no learning occurs, there is nothing to remember. If no memory forms, learning is not possible.

43
Q

Hebb’s rule

A
  • “Neurons that fire together, wire together”
  • States that learning involves the establishment and strengthening of neural connections
  • LTP provides evidence in support of this
44
Q

Strengthening and weaking of synaptic connections

A
  • Strengthening – repepetitive use of synaptic connections (growth of new, additional connections)
    • When neurons are continuously activated at the same time, the structure of the synapse changes
    • Makes them more likely to fire together again
    • Signals are transmitted more efficiently
  • Weakening – disuse of synaptic connections
    • Results in the decay or elimination of a synapse
    • Makes them less likely to fire together in the future
45
Q

Sprouting, rerouting and pruning

A
  • Sprouting – creation of new extensions on a neuron to allow it to make new connections with other neurons
    • Via growth of nerve endings on axons / dendrites
  • Rerouting – establishment of new connections between neurons to create alternative neural pathways
    • May be used to avoid damaged neurons
    • Can involve LTP / LTD
  • Pruning – removal of ineffective or unnecessary synapses to make useful neural pathways more efficient
    • Follows the “use it or lose it” rule
46
Q

Purpose of synaptic sprouting, rerouting and pruning

A
  • Facilitates synaptic plasticity
  • Enable us to adapt to changing & complex environments
  • Allow neurons to compensate for lost function (and maximise remaining function) following brain injury
47
Q

Long-term potentiation (LTP)

A
  • Long-lasting strengthening of synaptic connections
  • Postsynaptic N become more responsive to presynaptic N due to repeated strong stimulation (coactivation)
  • Increases the efficiency of neural transmission
  • Enhances memory; allows us to quickly retrieve info
  • Follows Hebb’s rule
48
Q

Functional and structural changes of LTP

A
  • Functional changes
    • ↑ neural connection due to repeated coactivation
    • Efficient communication and enhanced memory
  • Structural changes
    • ↑ branches on axon terminals of presynaptic N and dendrites on postsynaptic N (via sprouting)
    • Presynaptic N release more excitatory NTs (e.g. glu), increasing the firing of action potentials
    • Postsynaptic N form more glu receptors and reposition old ones to better positions (near active synapses via rerouting)
49
Q

Long-term depression (LTD)

A
  • Long-lasting weakening of synaptic connections due to the lack of stimulation between neurons
  • Communication at the synapse is weakened or silenced
  • Allows for the pruning of unnecessary connections, providing space for new neural connections
50
Q

Functional and structural changes of LTD

A
  • Functional changes
    • Lack of stimulation weakens the neural connection
    • Inefficient communication and weakened memory
    • Postsynaptic N less responsive to presynaptic N
  • Structural changes via pruning
    • Less dendrites on post-synaptic neurons
    • Decreased receptors on dendrites
    • Decreased synaptic connections between neurons
    • Elimination of weak or unused synapses
51
Q

Similarities of LTP and LTD

A
  • Activity dependent (i.e. high / low stimulation)
  • Involve glutamate and occur at glutamate synapses
  • Long-lasting effects (long-lasting neural plasticity)

Psychology U3/4 (11 decks)

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