biopsych

• Central nervous system (CNS)


  Comprises the brain and spinal cord, responsible for controlling important physiological processes and initiating/controlling behaviour
• Brain


  • Information processor that oversees the running of the body and the coordination of behaviour, as well as giving us conscious awareness
  • Made up of a series of billions of neural connections
• Parts of the brain


  • Thalamus
  • Hypothalamus
  • Hippocampus
  • Pituitary gland
  • Midbrain
  • Brainstem
  • Pons
  • Medulla
  • Cerebellum
  • Spinal cord
  • Corpus callosum
  • Cerebral cortex
• Cerebrum


  • Largest part of the brain, divided into two hemispheres that communicate via the corpus callosum
  • Each hemisphere has four lobes that deal with specific functions
• Cerebellum


  • Located at the back beneath the cerebrum, associated with motor skills and balance
  • Coordinates muscles and enables precise controlled movements
  • Abnormalities can affect speech, movement, and cause epilepsy
• Brain stem


  • Connects the spinal cord to the rest of the brain, transmits motor and sensory information
  • Responsible for regulating automatic body functions like breathing, heartbeat, swallowing
• Spinal cord


  Main function is to transmit information between the brain and the rest of the body, allowing the brain to respond to incoming information and control/regulate activity
• Spinal cord


  • Has pairs of spinal nerves that branch off and connect with different organs, muscles, and glands
  • Damage to the spinal cord prevents information relay to/from parts below the area of damage
• Spinal cord


  • Enables some simple reflex actions to be performed without brain involvement
• Peripheral nervous system


  Made up of the somatic and autonomic nervous systems, responsible for communicating information between the CNS and areas outside the brain
• Somatic nervous system


  Communicates with muscles and gets sensory information from the skin, has both motor and sensory neurons, deals with reflex actions
• Autonomic nervous system


  • Responsible for controlling bodily processes we're not consciously aware of, like regulating heartbeat and digestion
  • Divided into sympathetic and parasympathetic systems with opposite effects
• Sympathetic nervous system


  • Galvanises the body to deal with emergencies and threats, brings about the "fight or flight" stress response
• Parasympathetic nervous system


  • Counters the actions of the sympathetic system, brings the body back to a resting state after a crisis has passed, involved in energy conservation and digestion
• Neuron


  • Nerve cell highly specialised to communicate information around the nervous system
  • Average human brain contains 100 billion neurons, each connected to about 100 others
• Neuron structure


  • Large cell body containing nucleus and organelles, dendrites that receive information, axon that carries information away, terminal buttons that communicate with next neuron
  • Axon encased in myelin sheath with nodes of Ranvier to speed up transmission
• Sensory neurons


  Carry information from sensory receptors to the brain, convert sensory information into neural impulses
• Relay neurons


  Most common type, communicate between motor and sensory neurons within the CNS
• Motor neurons


  Located in the CNS, project axons out to directly or indirectly control muscles, activation causes muscle contraction, inhibition causes relaxation
• Transmission of information within a neuron


  Electrical impulse (action potential) travels along the neuron as the inside becomes positively charged relative to the outside
• Synaptic transmission


  1. Electrical impulse reaches presynaptic terminal, triggers release of neurotransmitters

  2. Neurotransmitters cross synapse and bind to receptors on postsynaptic neuron

  3. This either generates or prevents an electrical impulse in the postsynaptic neuron

  4. Remaining neurotransmitter is taken back up or broken down to end the process
• Excitation and inhibition


  • Neurotransmitter binding can either depolarize (excite) or hyperpolarize (inhibit) the postsynaptic membrane
  • Summation of multiple excitatory and inhibitory inputs determines if an action potential is generated
• Neurotransmitter re-uptake


  1. Remaining neurotransmitter in the synapse being taken back into the presynaptic neuron and stored for later use

  2. Neurotransmitter can be 'turned off' by enzymes once it has stimulated the post-synaptic neuron so that it is no longer effective
• Synaptic transmission


  1. Electrical impulse moves along the axon

  2. Inside of the neuron becomes positively charged relative to the outside

  3. Vesicles release neurotransmitter

  4. Neurotransmitter crosses synapse

  5. Neurotransmitter binds to receptors

  6. Electrical impulse is either triggered or prevented from being triggered in post-synaptic neuron
• Excitation


  Some neurotransmitters cause depolarisation of the post-synaptic membrane, making the post-synaptic neuron more likely to trigger an action potential
• Excitatory neurotransmitters


  • Dopamine
  • Adrenaline
  • Acetylcholine
• Inhibition


  Some neurotransmitters cause hyperpolarisation of the post-synaptic membrane, making the post-synaptic neuron less likely to trigger an action potential
• Inhibitory neurotransmitters


  • Serotonin
  • GABA
• Summation


  Receptors on a post-synaptic neuron can be stimulated by excitatory and inhibitory neurotransmitters at the same time, and the effects are summed
• If the net effect on the post-synaptic neuron is excitatory, the neuron will be more likely to generate an action potential
• If the net effect on the post-synaptic neuron is inhibitory, the neuron will be less likely to generate an action potential
• Hypothalamus


  Responsible for controlling the pituitary gland, the control centre of the endocrine system
• Endocrine system


  System of glands that secrete chemicals called hormones, works alongside the nervous system to control and regulate physiological processes
• Negative feedback


  Mechanism that maintains a stable balance of hormones in the body, like a thermostat regulating temperature
• Negative feedback mechanism


  1. Hypothalamus sends releasing hormone to pituitary gland

  2. Pituitary gland produces stimulating hormone that triggers release of hormone from target organ

  3. When final hormone level rises, hypothalamus detects this and shuts down production of its releasing hormone
• Target cells


  Cells with receptors for a specific hormone, which respond to that hormone
• Anterior pituitary gland


  • Produces ACTH in response to stress, which travels to adrenal glands and triggers release of cortisol
  • Produces LH and FSH, which stimulate the ovaries and testes
• Posterior pituitary gland


  Secretes oxytocin, involved in childbirth and mother-infant bonding
• Adrenal cortex


  Stimulated by ACTH from pituitary gland, produces cortisol and other hormones
• Adrenal medulla


  Produces adrenaline and noradrenaline, which bring about the fight or flight response