AOS1 U3

What is the main function of the human nervous system (CPR)?

Receives and processes information to coordinate a response.

What does the central nervous system consist of?

The brain and spinal cord.

What role does the brain play in the nervous system?

It receives and processes sensory stimuli from the body and coordinates responses.

What type of movement is associated with the central nervous system?

Voluntary movement.

Where does the spinal cord carry sensory information?

To the brain, from the body.

What is an involuntary reflex response initiated by?

The spinal cord without the input of the brain.

What are sensory neurons responsible for?

Carrying sensory info via afferent pathways to the spinal cord.

What do interneurons in the spinal cord do?

Initiate an involuntary motor movement.

Interneuron

communicates between sensory and motor neurons, by connecting them both (only found in CNS + spinal cord)

How does the peripheral nervous system function?

Transmits information to the CNS from the body's muscles and acts on information from the CNS.

Subdivisions of the autonomic nervous system and its role

Sympathetic and parasympathetic nervous systems.

Its main role is to regulate involuntary physiological processes (heart rate, blood pressure, digestion, respiration) and managing the body’s immediate response to stress and its recovery.

Sympathetic nervous system physiological responses

• dilated pupils

• stimulates glucose levels

• bladder relaxes

• increases production of perspiration

• increases flow of blood

What does the parasympathetic nervous system (PNS) regulate and its responses

aims to counterbalance the stressors effect and maintain homeostasis

• pupils constrict

• bronchioles constrict

• stimulates bile producion (digestion)

• bladder contracts

• decrease of perspiration

How does the spinal reflex arc work?

Involves sensory (afferent) neurons, relay neurons, and motor (efferent) neurons to produce a response.

Spinal reflex process

1. sensory stimuli is detected by sensory receptors

2. sensory neurons carry info via afferent pathway to spinal cord

3. interneurons in spinal cord initiate an involuntary motor movement

4. which are relayed to motor neurons, carried via efferent pathways to muscles

5. muscles perform response w no input from brain

How is synaptic communication achieved?

Chemical communication between neurons through neurotransmitters (neural transmission)

Neural transmission process

1. Action potential reaches the axon terminal at the end of the pre-synaptic neuron

2. Synaptic vesicles move to the edge of neuron where the terminal button releases the NT

3. The NT then bind to receptor sites on the dendrites of the post-synaptic neuron

4. NT either makes the post-synaptic neuron more/less likely to fire

What occurs during the lock and key process of neurotransmission?

Neurotransmitters bind to receptor sites, triggering responses in the postsynaptic neuron.

Explain the function of GABA

The main inhibitory neurotransmitter that acts as a brake on the NS, counteracting the effects of the excitatory NT (glutamte)

Synaptic plasticity vs neural plasticity

Synaptic plasticity is changes that occur within the synapse due to experience whereas neural plasticity is the ability of the brain to change, grow and reorganise

LTP

Relatively long lasting strengthening of synaptic connections, increasing neural transmission efficiency and tendency to fire together after they have been electrically stimulated

Define LTD and what does it result in?

Relatively long lasting weakening of synaptic connections, increasing the efficiency of neural transmission

→

Weakening of synaptic connections, making neurons less receptive to information resulting from repeated low levels of stimulation, aiding in adaptive learning

Sprouting

The growth of new extensions on a neuron to create lots of new synaptic pathways

Rerouting

The formation of alternative synaptic pathways to bypass damaged areas. (new synaptic connections between neurons)

Pruning

Removal of weak or unused synapses to increase efficiency.

What constitutes the gut-brain axis?

The bidirectional communication network between the CNS and the ENS (brain and gut).

Role of the Enteric nervous system (ENS)

Controls the gastrointestinal (digestive) tract is independently of the CNS (brain + spinal cord) but communicates with them through the GBA

How can chronic stress impact gut microbiota?

It can reduce microbial resistance, increasing susceptibility to stress-related disorders such as anxiety and depression as well as a poor digestive health system.

What are common internal stressors?

Pain, illness, and mindset factors such as expectations and feelings.

What is the difference between acute and chronic stress?

Acute stress tend to be short-lived but more intense while chronic stress is sustained feelings of stress and detrimental.

Beneficial physiological effects that cortisol has

• Increases glucose levels and heightens alertness, proving energy

• diverts energy from (inhibits) non-essential functions to prioritise survival

• enhances metabolism

• anti inflammatory effect

Why can prolonged cortisol be detrimental?

• suppresses the immune system

• increase risk in illness + autoimmune diseases

• increase risk of psychiatric conditions such as anxiety & depression

• blood sugar imbalances

• cognitive impairment

• digestive issues → risk of ulcers

Shock phase in the alarm stage of GAS?

• body temperature, muscle tone and blood pressure drops

• acute stress response

• resistance is below normal

• body responds to the immediate threat/challenge

Counter shock phase in the alarm stage of GAS?

• body attempts to compensate for the acute stress response

• release of adrenaline, non-adrenaline, cortisol

• inhibits digestion and other non-essential functions, diverting energy for survival

• increase in muscle tension, heart rate, blood glucose and and temperature

What characterises the resistance stage of stress?

Sustained release of cortisol to help the body adapt to stressors.

→ continues to stimulate glucose release from the liver to ensure sustained energy

→ keeps blood sugar levels high, preventing fatigue but can lead to insulin resistance

• physical signs of wear and tear begin to appear such as flu symptoms and lethargy (sluggish)

What occurs during the exhaustion stage of stress?

Depletion of bodily resources and increased susceptibility to illness.

• chronic fatigue

• unable to maintain normal physiological functioning

• increase risk in psychosomatic illnesses

What is the primary focus of Lazarus and Folkman’s transactional model?

Individual differences in stress response based on their appraisal of the situation

• stress only elicited if event is perceived as exceeding ones ability to cope

What does primary appraisal evaluate?

The significance of the situation

What does secondary appraisal evaluate?

Resources for coping

What is coping flexibility?

The ability to modify coping strategies to meet the demands of different stressful situations.

Indicators of high coping flexibility

• able to recognise whether the use of a coping strategy is effective

• ability to discontinue a coping strategy and implement a new and alternative one that is more effective

What are approach coping strategies?

Efforts to confront and actively deal with stressors.

What are avoidance coping strategies?

Efforts to not directly deal with a stressor.

Benefit of approach strategies?

They lead to fewer psychological symptoms and reduces the likelihood of prolonged distress

Limitation of avoidance strategies?

Excess reliance can prevent individuals from responding to stressors effectively and can be detrimental when action is required immediately

What is a psychosomatic illness?

Physiological symptoms resulting from psychological stressors.

What neurotransmitter is dominant in the hippocampus regarding memory?

Glutamate.

What can low levels of serotonin lead to?

Increased impulsivity and likelihood of aggressive behaviour.

What is the role of dopamine in the brain?

Involves the reward pathway linked to hunger, thirst, and addiction. It also has a role in movement, pleasure, attention and mood

What is the role of the synaptic vesicles?

Tiny sacs that store neurotransmitters in the presynaptic neuron.