Psych Unit 3 | AOS1 | Nervous Systems

• The central nervous system (CNS) is the brain and spinal cord. The central nervous system's responsibilities include receiving, processing, and responding to sensory information.
• The peripheral nervous system (PNS) consists of all nerves outside the CNS. It includes both afferent neurons that carry impulses toward the CNS and efferent neurons that carry impulses away from the CNS.
• the sympathetic nervous system is a branch of the autonomic nervous system (ANS) is responsible for activating the body's visceral organs, muscles and glands to trigger a fight-flight-freeze response.
• Sympathetic responses

  • Dilates pupils of the eyes to allow more light to enter the eyes and subsequently improve sight where needed
  • Heart rate increases to energise the body for activity by increasing blood flow
  • Lung airways relax and expand to allow for increased oxygenation required for more intense activity
  • Digestion is inhibited to allow for more essential bodily functions needed during activity
  • Blood flow increases to allow for efficient movement of skeletal muscles
  • Adrenal glands secrete stress hormones to energise the body
  • The body increases the release of glucose to energise the body
• the somatic nervous system is a branch of the PNS is responsible for sending motor information from the CNS to the body's skeletal muscles and bringing sensory information from the body to the CNS in order to formulate voluntary movements. This branch of the nervous system is responsible for all voluntary movements and actions performed by an organism.
• The fight-flight-freeze response is an unconscious and involuntary response initiated by the sympathetic nervous system and prepares the body to confront a stressful situation to optimise the chance of survival. This results in the person fighting the stimulus, fleeing or freezing.
• What is the process of a spinal reflex

  1. Sensory stimulus is detected by sensory receptors.
  2. Sensory neurons carry the information via sensor (afferent) paths to the spinal cord.
  3. Interneurons in the spinal cord, initiate involuntary muscle movement.
  4. This message is relayed to motor neurons and carried by efferent pathways to the skeletal muscles.
  5. Skeletal muscles preform the reflex response without any input from the brain.
  6. The brain then processes the movement afterwards.
• Efferent means away, ie. a pathway away from the brain and towards a muscle. MOTOR
• Afferent means toward, ie a pathway away from the body/muscle and towards the brain. SENSORY
• A synapse is a little gap between presynaptic and postsynaptic neurons in which neurotransmitters are sent, allowing neurons to send messages and communicate.
• The process in which leftover/remaining neurotransmitters are taken up by the cell again is a process called reuptake.
• A neurotransmitter is a chemical substance produced by a neuron that carries a message to other neurons or cells in muscles, organs or tissues.
• Neurotransmitters can be excitatory or inhibitory depending on their effect on the receiving neuron.
• a neurohormone is a neurotransmitter that also occurs as a hormone.
• neuromodulators are a subset of neurotransmitters that influence the action of other neurotransmitters (inhibitory and excitatory).
• the autonomic nervous system controls involuntary actions such as heart rate, breathing, digestion etc.
• the sympathetic division of the ANS prepares us for fight or flight situations.
• the parasympathetic division of the ANS restores our body back to normal when we have finished fighting or fleeing.
• the enteric nervous system is located within the walls of the gastrointestinal tract and regulates its own functions independently from the CNS.
• Glutamate is the main excitatory neurotransmitter in the CNS. This means that glutamate enhances information transmission by making postsynaptic neurons more likely to fire.
• Without GABA, the activation of postsynaptic neurons might get out of control, which might lead to seizures. Low levels of GABA can result in anxiety due to the lack of the calming effect GABA produces.
• Dopamine acts on areas of the brain to give you feelings of pleasure, satisfaction and motivation. Dopamine also has a role to play in controlling memory, mood, sleep, learning, concentration, voluntary movement and other body functions. Dopamine is addictive. Dopamine is an inhibitory and excitatory modulatory NT.
• Serotonin plays a key role in such body functions as mood stabilizing, sleep-wake cycle, digestion, nausea, emotional processing, appetite, blood clotting and sexual desire. Serotonin is an inhibitory modulatory NT.
• Sprouting is the creation of new extensions on a neuron allowing it to make more connections with other neurons. This occurs through the growth of nerve endings.
• Long term potentiation refers to the long term/long lasting enhancement of synaptic transmission due to the repeated strong simulation. This leads to significant improvements in the ability of the two neurons communication.
• Neuroplasticity is the brains ability to change its structure and function throughout life. It allows us to adapt to our environment and learn from experience.
• hebbs rule states that any two cells (neurons) that are repeatedly active at the same time will tend to become 'associated,' so that activity in one facilitates activity in the other.

  'Neurons that fire together wire together'.
• the autonomic nervous system is made up of the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.
• The parasympathetic nervous system slows down bodily processes when we are relaxed. It decreases heart rate, breathing rate, blood pressure, constricts pupils, reduces saliva production and increases intestinal motility.
• The sympathetic nervous system prepares the body for action by increasing heart rate, breathing rate, blood pressure, pupil dilation, sweating and releasing glucose into the blood stream. The SNS is responsible for the fight or flight response.
• the parasympathetic ns is a branch of the autonomic nervous system responsible for returning and maintaining the body's visceral organs, muscles and glands at their optimal and balanced functioning/set point.
• sensory neurons are neurons that carry information (sensory neural messages) about the body sensations from the PNS to the CNS.
• The terminal buttons of a neuron are the little knobs at the end of an axon that release neurotransmitters. Neurons transmit signals to other neurons through the use of these terminal buttons.
• The transfer of information between neurons is called neural transmission
• In a neuron, synaptic vesicles (or neurotransmitter vesicles) store various neurotransmitters that are released at the synapse.
• Excitatory neurotransmitters have excitatory effects on the neuron. This means they increase the likelihood that the neuron will fire an action potential.
• Inhibitory neurotransmitters decrease the likelihood that the neuron will fire an action potential.
• A receptor site is where a neurotransmitter binds with its target cell.
• rerouting is when new connections are made between neurons to create alternate pathways. This may involve existing connections or new connections from the sprouts.
• pruning is the elimination of weak/underused synapses & therefor connections with other neurons are formed. The synapses that are frequently used are retained and those that aren't decay/disappear.