Unit 3 AOS 1 Flashcards
Nervous System and Stress
what is the human nervous system?
A complex, highly organised communication system between the body’s internal cells and organs and the external world.
Three main functions of the human nervous system?
- Receive information
- Process information
- Coordinate/Respond to information
what is the CNS comprised of?
brain and spinal cord
what is the CNS main function?
to receive and transmits neural messages to and from the PNS, process it and to activate appropriate responses
what is the brain and what is its function?
A highly complex organ contained within the skull that coordinates mental processes and behaviour, and regulates bodily activity. The brain is responsible for everything we think, feel and do.
what is the spinal cord?
long, thin bundle of nerves that extends from the base of the brain to the lower back.
what is spinal cords function?
to enable neural communication between the brain and the rest of the body, also initiates spinal reflexes
what tracts is the spinal cord comprised off?
Afferent tracts, which transmit sensory (afferent) messages from the PNS to the brain [incoming message to brain]
Efferent tracts, which transmit motor (efferent) messages from the brain to the PNS [outgoing message from brain]
what is the memory tip for sensory and afferent tracts/neurons?
SAME
what is the PNS comprised of?
All network of neurons within the body, outside of the brain and spinal cord (CNS).
Comprised of muscles, organs and glands (MOG)
what is the PNS further divided into?
the somatic and autonomic nervous systems
two main roles of the PNS?
- Carries information TO the CNS from the body’s muscles, organs and glands (internal) and from the sensory organs (external). [Sensory function]
- Carries motor information FROM the CNS to the body’s muscles, organs and glands. [Motor function]
what is the autonomic nervous systems (unconscious) function?
- Controls involuntary movement and functioning
- autonomous self regulates activity of visceral muscles, organs and glands without conscious control (involuntarily)
- Network of neurons that carry neural messages between the CNS and visceral muscles , internal organs and glands
- Responsible for keeping our internal functioning at a stable level (called homeostasis) and preparing our bodies to deal with threatening situations (fight flight response).
- Regulates activity of visceral muscles, organs and glands (e.g heart, lungs, sweat glands etc)
- Relays info to internal organs
- Connects CNS to internal organs and glands, self regulating
what are the two sub divisions of the autonomic nervous system?
Sympathetic NS and Parasympathetic NS
what is the sympathetic nervous system and functions?
- prepares body for action
- Activates internal muscles, organs and glands to prepare the body for vigorous activity or to confront or flee a stressful/ threatening situation.
- activates the fight/flight/freeze response
- activated by a stressor or fear stimulus and enhances survival by providing an immediate response, in a split second, to any kind of emergency
- increases arousal
what is the parasympathetic nervous system and functions?
- calms body for action
- In times of minimal stress and in the absence of threat, it helps to maintain the internal body environment in a steady, balanced state of normal functioning (homeostasis).
- Counterbalances the activities of the sympathetic nervous system
- Restores the body to a state of calm/equilibrium (homeostasis) after threat/cause of stress is no longer present
- counterbalancing and homeostasis are the 2 main functions
Why can’t we just stay in the sympathetic nervous system all the time?
Your body’s resources would become depleted and the MOG would not be able to maintain that level of arousal
Which is more dominant day-to-day?
Sympathetic NS OR Parasympathetic NS?
Parasympathetic nervous system, it is involved in everyday activities and routines
however they are both active at the same time, however one system is usually dominant at any given time
when does the autonomic nervous system function?
continuously, whether we are awake, asleep, active, under anesthetic or even in a coma, therefore maintains our survival
what is the somatic nervous systems function?
- Controls voluntary movement
- Initiates skeletal muscle movement
- Specialises in control of voluntary movements and communication of information to and from the sense organs
- Conscious awareness or voluntary control
- relays info to and from skeletal muscles
- Carries messages from sensory receptors in the body to the CNS, and motor messages from the CNS to skeletal muscles
what is the somatic nervous system comprised of?
network of nerves within the body, connected to our sensory receptors and skeletal muscles
what is the somatic nervous systems function in reference to SAME?
- Carries sensory (afferent) information from sensory receptor sites (skin, muscles, joints and tendons) and carried along sensory neural pathways to the CNS.
- Carries motor (efferent) information from the CNS along motor neural pathways to skeletal muscles to control voluntary movements.
physiological sympathetic response for pupils?
dilates to let light in to improve vision
physiological sympathetic response for salivary glands?
decrease salivation as not necessary, result of increased hormone secretion
physiological sympathetic response for heart?
accelerates heart rate to pump blood faster, increases blood flow, to enable high levels of physical activity
physiological sympathetic response for bronchioles of lungs?
dilates/relaxes to take in more oxygen, to increase oxygenation, enabling high levels of physical activity
physiological sympathetic response for stomach?
decrease contractions/inhibits digestion to conserve energy for high levels of physical activity
physiological sympathetic response for liver?
increase in glucose release to energise the body
physiological sympathetic response for gallbladder?
inhibits the release of bile, conserving energy by not contributing to digestion
physiological sympathetic response for adrenal glands?
stimulates hormone secretion (stress hormones) to energise body (increase in heart rate and blood pressure and breathing rate, relaxation of intestinal muscle)
physiological sympathetic response for bladder?
relaxes and slows contraction rate, causes excretion, to conserve energy
physiological sympathetic response for intestine?
inhibits secretion to conserve energy
physiological sympathetic response for blood pressure?
increases for higher levels of oxygen for activity
physiological sympathetic response for sweat glands?
increases perspiration to cool body
physiological sympathetic response for sex organs?
stimulated due to increase hormones
physiological parasympathetic response for pupils?
contracts according to external light levels, gives near vision, allows for appropriate amount of light for adequate vision
physiological parasympathetic response for salivary glands?
increases salivation back to normal functioning from normal hormone increased secretion levels
physiological parasympathetic response for heart?
slows heart rate back to normal, steady and regular, supports optimal and balanced functioning
physiological parasympathetic response for bronchioles of lungs?
contracts, to enable a steady and regular breathing rate for optimal functioning
physiological parasympathetic response for stomach?
increases contractions/stimulates digestion, allows for normal functioning/digestion
physiological parasympathetic response for liver?
decreases the release of glucose back to normal, allows body to rest and prevents depletion of energy stores
physiological parasympathetic response for gallbladder?
stimulates release of bile, allows for normal digestion
physiological parasympathetic response for adrenal glands?
inhibits hormone secretion, allows body to rest
physiological parasympathetic response for bladder?
increases to contractions return to normal functioning, urination can be controlled
physiological parasympathetic response for intestine?
increases contractions, enables normal functioning and optimal functioning
physiological parasympathetic response for blood pressure?
decreased/slows pumping of blood, returns to normal functioning, enables a steady and regular blood pressure for optimal functioning
physiological parasympathetic response for sweat glands?
decreases respiration, regulates normal and optimal functioning
physiological parasympathetic response for sex organs?
unstimulated caused by inhibited hormone secretion
what is a neuron?
nerve cell that receives and transmits neural information
what is the nervous system composed of?
The nervous system is composed of billions of neurons arranged in neural pathways along which neural messages are transmitted.
what are the three types of neurons?
- motor neurons (efferent neurons)
- sensory neurons (afferent neurons)
- interneurons
what are motor neurons?
Motor neurons (also known as efferent neurons), which transmit neural messages about motor movement from the CNS to the PNS
what are sensory neurons?
Sensory neurons (also known as afferent neurons), which transmit neural messages about bodily sensations from the PNS to the CNS
what are interneurons?
Interneurons, which transfer neural messages between sensory neurons and motor neurons. The CNS, including the brain and spinal cord, is made up of interneurons
what is a conscious response?
A conscious response to a sensory stimulus is a reaction that involves awareness to external and internal stimuli.
Involve purposeful, voluntary and intentional reactions
examples of conscious responses?
walking, talking, waving, putting on a jumper, waving (somatic NS functions)
what is an unconscious response?
An unconscious response to a sensory stimulus is a reaction that does not involve awareness.
It is involuntary, unintentional, automatic and we cannot ordinarily control its occurrence
Regulated by the ANS
examples of unconscious responses?
functioning of your heart, digesting your food (regulated by the ANS)
differences of conscious responses to unconscious responses?
- Reaction involves awareness
- Paid attention to stimulus
- Voluntary or intentional reaction
- Often goal directed or purposeful.
- Can be more complex response
- Tend to vary
- Can be learnt
- Can control it
differences of unconscious responses to conscious responses?
- Reaction does not involve awareness
- Don’t have to pay attention for it to happen
- Involuntary or unintentional
- Reflexive or automatic, increasing chances of survival
- Most are simple responses
- Tend to occur in the same way each time
don’t require learning - May not be able to control it
what is a spinal reflexes?
A spinal reflex is an unconscious and automatically occurring response to certain stimuli without any involvement of the brain (initiated by neurons in the spinal cord, called interneurons), it is a reflex involving contraction of skeletal muscles
A motor response has occurred before the brain processes a conscious perception of pain
what type of response is a spinal reflex?
The spinal reflex is an adaptive response, it saves time in a situation which may be very harmful to an organism (lessens damage/injury)
what are the steps of the spinal reflex?
- Receptor site (skin) receives sensory stimuli (prick)
- Sensory neurons transmit the message along afferent pathways to the spinal cord
- Interneurons in the spinal cord relay the message to motor neurons
- Motor neurons transmit the message along efferent pathways to hand muscles causing a withdrawal reflex
- Whilst the spinal reflex is occurs, sensory neurons also carry the neural message further up the spinal cord to the brain
- The brain then consciously perceives/interprets the sensory information as pain (WHY? = adaptive / for survival purposes so you can learn from it)
what is the cell body (soma)?
contains nucleus, contains DNA
what are the dendrites?
receives messages from other cells
what is the axon?
passes messages away from the soma to other neurons, muscles or glands
what are the myelin sheath?
covers the axon of some neurons and helps speed neural impulses
what is action potential?
electrical signal travelling down the axon
what are the terminal buttons?
stores and secrete neurotransmitters
how are neurons arranged?
in neural pathways in the nervous system, where neural messages are transmitted
what is the synapse?
Where two neurons meet (axon terminals of the pre-synaptic, the synaptic gap, and the receptor sites on dendrites of the post-synaptic neuron)
what are neurochemicals?
chemical substances that transmit neural information
where are neurochemicals released?
They are released from the presynaptic neuron, travel across the synaptic gap and are received by the receptor sites on dendrites of the post synaptic neuron.
what are the two types of neurochemicals?
Neurotransmitters and Neuromodulators
how do neurochemicals bind?
Each neurochemical has a distinct molecular structure that corresponds to a specific receptor site. Therefore, it will only bind to its matching/complementary receptor site.
what are neurotransmitters?
Chemical molecules that have an affect on one or two postsynaptic neurons
features of neurotransmitters?
→ Enables rapid communication between neurons
→ Neurotransmitters are fast-acting, localised - at a single synapse - and short lived
→ Meaning the neurotransmitter is released into the synapse, attaches to postsynaptic receptors and any excess neurotransmitter is reabsorbed or broken down by enzymes
(glutamate and GABA)
what type of neurotransmitter is glutamate?
The primary excitatory neurotransmitters that stimulate postsynaptic neurons to perform their functions (increases likelihood of post synaptic neuron firing an AP)
- Enhances information transmission by making post-synaptic neurons more likely to fire
what type of neurotransmitter is GABA?
The primary inhibitory neurotransmitters that block, prevent, or suppress postsynaptic neurons from firing an AP
what are the two most common neurotransmitters in the CNS?
glutamate and GABA, neurons in virtually every brain area use these two chemical messages to communicate with each other
- Glutamate is the second most abundant neurotransmitter in the brain
what are the roles of glutamate?
- The release of glutamate is associated with learning and memory
- The excitatory effects of glutamate form and strengthen synaptic connections between neurons that are repeatedly activated during learning
These connections represent memories of what has been learned
Thus, glutamate enables synaptic plasticity
what happens is there is too much or too little glutamate in the brain?
Too much or too little glutamate can be harmful to neurons and brain functioning as a whole.
Abnormally high concentrations of glutamate can result in overexcitation of receiving neurons causing neuronal damage and/or death.
what are the roles of GABA?
- Regulates postsynaptic activation in neural pathways, preventing over-excitation of neurons
- To fine-tune and maintain neurotransmission at an optimal or ‘best-possible’ level
- Without the inhibitory effect of GABA, activation of postsynaptic neurons might get out of control causing uncontrolled activation which may result in seizures
- able to inhibit heightened awareness therefore reduces anxiety and important role in preventing seizures
- It is involved with the regulation of anxiety and is associated with calmness
how to glutamate and GABA balance each other?
- The inhibitory effect of GABA counterbalances the excitatory activity of glutamate and vice versa
- Consequently, GABA and glutamate have important roles in regulating CNS arousal
- An excess or over-production of particular neurotransmitters is associated with particular disorders
what are neuromodulators?
Chemical molecules that have an effect on multiple postsynaptic neurons. (dopamine and seretonin)
features of neuromodulators?
- Neuromodulators have widespread modulatory effects as they can influence large areas of brain tissue.
- Neuromodulators produces relatively long-lasting effects, as they modulate neural activity more slowly than neurotransmitters.
- Neuromodulators diffuse (spread) through large areas of the brain; they are slow acting but will bring about long-lasting change to neurons and synapses affected.
- Like neurotransmitters, they bind to their specific receptor sites to have an effect on groups of post-synaptic neurons.
how can neuromodulators can also affect neurotransmitters?
→ changing the responsiveness of the receptor sites of a particular neurotransmitter, further enhancing excitatory or inhibitory effects
→ Changing the neurotransmitter release pattern of the presynaptic neuron
what is dopamine responsible for?
Dopamine is a neuromodulator primarily responsible for voluntary motor movement, the experience of pleasure, and reward based learning.
where is dopamine produced?
Dopamine is produced in the substantia nigra, as well as the ventral tegmental area, both located in the midbrain.
what effect does dopamine have on the post-synaptic neuron?
Dopamine can have excitatory and inhibitory effects on the post-synaptic neuron, depending on the type of receptor sites present at the particular brain location
what roles does dopamine have?
- Coordinates voluntary motor movement
- Important role in reward based learning
- Plays a role in motivation and addiction
- Role of dopamine in thirst and drinking
- Plays a role in hunger and eating
how does dopamine coordinate voluntary motor movement ?
→ Dopamine produced in the substantia nigra enables smooth, coordinated muscle movement
how does dopamine play an important role in reward based learning?
→ When someone is rewarded for doing a behaviour, dopamine that is produced in the ventral tegmental area is released, which is associated with the feeling of pleasure.
how does dopamine play a role in motivation and addiction?
→ Rewarding behaviors that trigger the release of dopamine have a pleasurable consequence for the person, and therefore more likely to be done again. In this way, dopamine can motivate the person to engage in rewarding behaviours over and over. Therefore, addictive behaviours, such as gambling and drug use, often provide intense pleasurable rewards for people, motivating them to repeat a behaviour, and therefore resulting in an addiction.
how does dopamine play a role in thirst and drinking?
→ The process of sipping water releases dopamine in the reward pathway, procucing feelings of pleasure
→ This suggests that the act of drinking water itself is rewarding , not the actual hydration.
how does dopamine play a role in hunger and eating?
→ consumption of food releases dopamine and provides a sense of pleasure.
→ this increases the likelihood of eating food the next time we experience hunger
→ hunger results from a decrease of dopamine levels in the brain, this triggers the sensation of hunger, then when we eat, dopamine levels increase, we experience pleasure and this pattern is reinforced
→ when we eat something we have been craving, the brain releases more dopamine into the reward pathway
where is seretonin produced?
Serotonin is produced from the raphe nuclei, which are masses of neurons in the brainstem
what effect does seretonin have on the post-synaptic neuron?
Serotonin has inhibitory effects on the
postsynaptic neurons
what roles does serotonin have?
- Mood regulation and stabilisation
- Regulates the sleep-wake cycle
what role does serotonin have in mood regulation and stabilisation?
→ Appropriate levels of serotonin in the brain enable a person to experience stable and positive moods, promoting wellbeing.
→ Low levels of serotonin are linked with mental illnesses such as depression, resulting in prolonged negative moods, reduced interest in daily activities and feelings of extreme worthlessness or excessive guilt.
→ medications to treat depression increase serotonin levels or target serotonin receptors in the brain (antidepressants are a type of SSRI (a selective serotonin reuptake inhibitor) meaning they block/prevent the reuptake of serotonin after it has been released, resulting in greater than usual levels of serotonin being available. This results in an instant & immediate improvement in mood.
what role does seretonin have in regulating the sleep-wake cycle?
→ which is the 24 hour cycle of sleeping and waking. Serotonin influences both quality and quantity of sleep as well as feelings of alertness and wakefulness during the day
what other roles does seretonin have?
Depending on the receptor sites it binds to and the brain area it acts upon, serotonin can also play a role in appetite, digestion and arousal.
what is synaptic plasticity?
The ability of synaptic connections to change over time in response to activity or experience/learning.
what does synaptic plasticity include?
This includes the formation, strengthening or weakening of synaptic connections.
The experiences you have throughout your life modify neural synapses, causing them to physically change.
what is learning?
Learning is the process of acquiring knowledge, skills, or behaviours through experience.
what is memory?
Memory is the process of encoding, storing, and retrieving information that has been previously encountered.
when do learning and memory occur?
Learning and memory are processes that constantly occur throughout life.
We learn and form new memories every day as we experience, engage, and interact with the environment.