U3AOS1A - Nervous System Functioning Flashcards
Cambridge 3B-C (48 cards)
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
What is a spinal reflex/reflex arc?
* **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
What are the steps of a spinal reflex?
* **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
Why is a spinal reflex adaptive?
* 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
Define neuron
* **Building blocks** of the nervous system
* Transmit messages **to and from the brain**, various functions
* Look **different depending on function**
29
Describe the 3 main types of neurons
* **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
Draw and label a neuron
* 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
Outline the steps of neurotransmission
* **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**
## Footnote
Uses electrochemical energy
32
Describe neurotransmission in terms of the synapse
* **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
Define neurotransmitter
* **Chemical** substance released by the **terminal button** of a neuron
* Necessary for **neural communication**
34
What is an excitatory neurotransmitter?
* **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
What is an inhibitory neurotransmitter?
* **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
What is a neuromodulator?
* **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
Describe dopamine
* **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
## Footnote
🔗- Learning and Memory
38
Describe serotonin
* **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
## Footnote
🔗- Gut-brain axis, stress, sleep-wake cycle
39
Distinguish between neurotransmitters and neuromodulators
* Modulators can **affect multiple synapses**
* Modulators tend to be **slower acting**
* Modulators can **influence effects of neurotransmitters** (alter receptor)
40
What is neuroplasticity?
* The ability of the brain to **physically change in response to experience**
* Two types - Developmental and Adaptive
41
What is developmental plasticity?
* Occurs **naturally across the lifespan**
* Certain critical periods that enable greater developmental plasticity
42
What is adaptive plasticity?
* Occurs as a **result of brain damage or trauma**
* Utilising critical periods for developmental plasticity helps enable greater adaptive plasticity
43
What is Hebb's rule?
* **'Neurons that fire together, wire together'**
* Neurons that **continuously interact** with each other will form a **strong synaptic bond**
44
What is long-term potentiation?
* **Long-lasting** and **experience-dependent strengthening** of synaptic connections that are **regularly activated**
45
What is long-term depression?
* **Long-lasting** and **experience-dependent weakening** of synaptic connections between neurons that are **not regularly activated**
46
What are the processes that neurons go through?
* **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
What are the 3 specific neural processes involved in synaptic plasticity?
## Footnote
SRP
* **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
What are two synaptic modifications that occur during sprouting?
* **Dendritic Branching**
* **Bushier dendrites** on the postsynaptic neuron
* **Filigree Appendages**
* **Growth** of the **axon terminal** on the presynaptic neuron
