AOS 1 Flashcards
neuron definition
a nerve cell; the building block of the nervous system
subdivisions of the human nervous system
CNS:
-> brain
-> spinal cord
PNS:
-> somatic NS
-> autonomic NS
—> sympathetic NS
—> parasympathetic NS
—> enteric NS
role of the central nervous system (CNS)
to process information and coordinate responses to sensory stimuli received by the body
CNS: the role of the brain
to process information received through neural pathways from the body, along with receiving, analysing and regulating sensory information and controlling all bodily actions and functions.
communication between the brain and the body
via the spinal cord and its nerves, as well as cranial nerves that connect the brain directly to organs and muscles of the body
CNS: the spinal cord (description + role)
description: a thin and dense bundle of nerve tissue that runs from the brainstem to the lower middle section of the spine.
role: allows the brain to communicate with the rest of the body by conveying messages between the PNS and the brain, as well as initiating simple motor reflexes which work independently from the brain
two main roles of the spinal cord
- carry incoming sensory information from the PNS towards the brain to be processed
- carry motor information initiated by the bran towards the body (PNS)
afferent pathways definition
sensory receptors within the body that carry sensory information towards the spinal cord.
efferent pathways definition
sensory receptors within the body that carry motor commands initiated by the brain to the muscles required to perform motor movements.
what is the peripheral nervous system (PNS)
the entire network of nerves located outside the CNS.
role of the PNS
- carry information to the CNS from the body’s muscles/organs/glands and from sensory organs
- carries information from the CNS to the body’s muscles, organs, and glands
somatic nervous system definition
the division of the peripheral nervous system that controls the body’s skeletal muscles
autonomic nervous system definition
A part of the peripheral nervous system responsible for regulating the activity of internal organs. It includes the sympathetic and parasympathetic nervous systems.
sympathetic nervous system definition
Activates internal muscles, glands, and organs to prepare the body to deal with vigorous activity or a stressful/threatening situation. It is activated by a stressor or fear stimulus. it enhances survival by producing an immediate response (fight or flight).
parasympathetic nervous system definition
In times of minimal stress and in the absence of threat, helps to maintain the internal body environment in a steady, balanced state (at homeostasis). counterbalances the activities of the sympathetic system and restores the body to a state of calm once the need for sympathetic nervous activation has passed.
two main functions of the parasympathetic nervous system
- Maintains a state of homeostasis
- Lowers arousal and calms the body once the threat has passed (counterbalances sympathetic NS)
enteric nervous system definition
The gastrointestinal tract that is part of the digestive system that comprises the organs that food and liquids travel through when they are swallowed, digested, absorbed, and leave the body as faeces.
conscious response definition
A response to a sensory stimulus is a reaction that involves awareness. The response will usually be a voluntary ‘intentional’ reaction. The reaction, even if it momentary usually is goal-directed and the individual will be able to hold some degree of control over it.
unconscious response definition
A response to a sensory stimulus is a reaction that does not involve awareness. It is involuntary. Unintentional, and automatic response which we have no control over
spinal reflex
An unconscious involuntary and automatically occurring response to certain stimuli without any involvement of the brain.
steps of the spinal reflex
(touching a sharp/hot object)
- Sensory receptors respond to the stimulation
- Send message that is carried by sensory neurons to the interneurons in the spinal cord.
- Interneurons in the spinal cord relay the message to the motor neurons
- Motor neurons carry the message along a motor pathway to the muscles causing a withdrawal reflex. The hand is moved away before pain is experienced.
- While the spinal reflex occurs, sensory neurons are also carrying the message further up the spinal cord to the brain
- The message is received in the brain (where sensory information is perceived) and pain is experienced
neurotransmitter definition
chemical messengers that cross the synaptic gaps between neurons
excitatory neurotransmitter definition
stimulate or activate postsynaptic neurons
inhibitory neurotransmitter definition
hinder or prevent postsynaptic neurons from firing
primary excitatory neurotransmitter example
glutamate
primary inhibitory neurotransmitter example
GABA (gamma-aminobutyric acid)
glutamate description
primary excitatory neurotransmitter within the CNS. It has the characteristics of enhancing information transmission by making postsynaptic neurons more likely to fire. The release of this neurotransmitter is associated with enhanced learning and memory.
relationship between glutamate and learning
plays an important role in learning and the formation of memories in the brain, by stimulating connections between neurons. It is released when a neural pathway is associated with an experience is stimulated
GABA description
the primary inhibitory neurotransmitter in the CNS. It has the characteristics to make postsynaptic neurons less likely to fire, as well as fine-tuning neurotransmission in the brain and maintaining neurotransmission at an optimal/” best possible” level. Without the inhibitory effect of this neurotransmitter, activation of postsynaptic neurons might get out of control.
agonists definition
(almost) mimic glutamate by stimulating receptors to fire more quickly
antagonists definition
(almost) mimic GABA because they stimulate receptors in neurons to slow/reduce firing
neuromodulator definition
a signaling molecule in the nervous system that influences the activity of neurons and neural circuits, exerting slower and more widespread effects than neurotransmitters to regulate various aspects of neural function and behaviour
neurotransmitters vs neuromodulators
neurotransmitters are chemicals released by a presynaptic neuron to send signals to the post-synaptic neuron
neuromodulators are chemicals released by neurons to alter the effectiveness of neural transmission
neurotransmitters= transmit chemical signals adjacently
neuromodulators= alter the neuron transmission of neurons by controlling the synthesis and release of neurotransmitters
neurotransmitters= released into synapse
neuromodulators= released outside synapse into neural tissue
neurotransmitter= target single post-synpatic neruon
neuromodulator= target groups of neurons
neurotransmitter= fast
neuromodulator = slow but last longer
dopamine as a neuromodulator description
is a multifunctional neurotransmitter with both excitatory and inhibitory effects that is involved in many of the CNS functions (pleasure, movement, mood, attention, cognition, and motivation).
dopamine definition
A neurotransmitter associated with movement, attention and learning and the brain’s pleasure and reward system.
the reward pathway definition
a group of structures within the brain that are activated by rewarding or reinforcing stimuli. This pathway controls our responses to natural rewards (sex, food, social interactions) and is therefore an important determinant of motivation.
relationship between dopamine and the reward pathway
exposure to natural rewards -> release of this chemical increased = modulating brain activity and structures alongside it.
higher release of this chemical = more stimulus sensed as a reward
influence of dopamine on thirst
** think from a survival perspective
· Gulping motion made by the throat once liquid is swallowed sends a message the brain that water has been consumed.
· Dopamine release paired with the gulping motion
influence of dopamine on hunger and eating
** think from a survival perspective
releases dopamine and gives us feelings of pleasure, which then increases our chances of eating food the next time we experience hunger.
· The brain receives signals from several hormones that indicate when food is needed or not. These signals modify dopamine output from the brain’s reward pathway - controlling our motivation for food.
influence of dopamine on addiction
Whenever we see a reward which we deem is “worth chasing”, our brains produce a higher level of dopamine, motivating us to complete the task no matter how unhealthy or difficult the task may be.
dopamine and food - reward pathway steps
- Dopamine levels decrease below baseline in the reward pathway of the brain
- This results in the sensation of hunger
- Increase in food seeking or eating behaviours
- Dopamine levels in the reward pathway of the brain increase above baseline when you eat
- Pleasure is experienced, reinforcing this pattern of brain activity and behaviour
dopamine and unhealthy behaviours cycle
- having an unhealthy behaviour (eg. gambling)
- increased dopamine released in the reward pathway, producing feelings of pleasure
- over time less dopamine is produced, diminishing the brain’s supply
- this increases the urge to continue seeking the same feeling of pleasure (causing addiction)
serotonin definition
inhibitory neurotransmitter that also acts as a neuromodulator, influencing a variety of brain activities. However, it is best known for its role in the brain where it modulates all human behavioural processes (mood, perception, reward).
influence of serotonin on mood
high levels of this chemical = mood improves
however, there are a lot of other chemical processes happening within the body, so it is difficult to determine a cause-and-effect relationship.
influence of serotonin on sleep
low levels of this chemical = disrupting rhythm of being awake and asleep
low levels = individual will have reduced pressure to sleep when required, thus increasing restlessness and wakefulness when they should be sleeping