Biopsychology

• Nervous system


  Body wide system of nerve cells that collects information from the world, processes this information and then takes action by directing bodily organs and muscles via the transmission of electrochemical messages
• Divisions of the nervous system

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
  • Autonomic nervous system (ANS)
  • Somatic nervous system (SNS)
• Central nervous system (CNS)


  Involves complex processing, includes the brain for all conscious and most unconscious processing, and the spinal cord which receives and transmits information and some reflex processing
• Peripheral nervous system (PNS)

  A body-wide network of messenger neurons, sensory afferent neurons take information to the CNS, motor efferent neurons take information away from the CNS
• Autonomic nervous system (ANS)


  The part of the PNS that controls actions of internal glands and is an involuntary system so not under conscious control
• Somatic nervous system (SNS)


  The part of the PNS that controls skeletal muscles, it's a voluntary system so under conscious control
• Parts of the ANS


  • Sympathetic system
  • Parasympathetic system
• Sympathetic system


  Part of the ANS, increases bodily activities, release of noradrenaline, activates the fight or flight response, increases heart rate, sweat, breathing rate, and dilates pupils
• Parasympathetic system


  Part of the ANS, decreases bodily activities, releases acetylcholine, activates the rest and digest response, decreases heart rate, sweat, and breathing rates, constricts pupils
• Homeostasis is maintained by a balance between the sympathetic and parasympathetic systems
• Endocrine system


  • Pituitary gland
  • Hypothalamus
  • Pineal gland
  • Thyroid gland
  • Adrenal glands
  • Ovaries
  • Testicles
• Pituitary gland


  Also known as the master gland, hormone A controls the release of hormones from other glands
• Hypothalamus


  Hormone CRH links the nervous system to the endocrine system
• Pineal gland


  Hormone melatonin modulates sleep pattern, keeping the body to a day-night rhythm
• Thyroid gland


  Hormone thyroxine modulates metabolism, the rate of use in the body
• Adrenal glands


  Hormone adrenaline regulates the effect of the fight or flight response
• Ovaries


  Hormone estrogen develops secondary sexual characteristics in females
• Testicles


  Hormone testosterone leads to the development of secondary sexual characteristics in males
• Components of the reflex arc

  • Sensory neuron
  • Relay neuron
  • Motor neuron
• Sensory neuron


  Its function is to detect sensations, for example pain, at sensory receptors. An action potential then travels across the nerve, passing along the myelinated axon, and then the electrical signal is converted into a chemical signal to cross the synapse.
• Relay neuron


  Its function is to aid transmission, a new action potential forms in the dendrites, this neuron is in the spine and sends a signal to the CNS but also immediately sends a signal along its axon to the motor neuron.
• Motor neuron


  Its function is to detect the signal from the relay neuron by a synaptic transmission and then pass the signal along its own myelinated axon to stimulate an effector, for example a muscle group in the arm, moving it away from the source of pain.
• Synaptic transmission


  The process where neurons communicate by passing on chemical signals. Neurotransmitters are the chemical messages released by neurons, which are either excitatory (stimulate) or inhibitory (make less likely).
• Development of an action potential


  1. Action potential travels down the axon of the presynaptic neuron

  2. This forces vesicles containing neurotransmitters to merge with the cell membrane and release neurotransmitter into the synaptic cleft

  3. Receptors on the postsynaptic neuron's dendrite membrane detect the presence of neurotransmitters, changing the chemistry within the postsynaptic neuron

  4. If the charge inside the postsynaptic neuron passes a threshold, a new action potential forms and the message is passed on

  5. The neurotransmitters detach from the receptors and return to the presynaptic cell via transport proteins, a process called reuptake
• Excitation


  Excitatory neurotransmitters increase the likelihood of a new action potential forming in the postsynaptic cell when detected by receptors. The electrical charge inside becomes more positive and likely to fire, a process called depolarization.
• Inhibition


  Inhibitory neurotransmitters decrease the likelihood of a new action potential forming in the postsynaptic cell when detected by receptors. The electrical charge inside becomes more negative and less likely to fire, a process called hyperpolarization.
• Summation


  The combined effect of all inhibitory and excitatory influences, resulting in a new action potential forming or not.
• Information can only be passed between the pre- and post-synaptic neurons in one direction, due to the structure of the synapse.
• Fight or flight response


  An evolutionary survival mechanism in response to a threat, it primes the body and mind for extreme action such as fighting for our life or escaping a threat. The body returns to homeostasis after the threat is passed.
• Activation of the fight or flight response

  1. A stressor is first detected by the hypothalamus

  2. The HPA axis in the endocrine system is activated and the pituitary gland releases the hormone ACTH

  3. This is detected by the adrenal cortex, releasing cortisol

  4. The hypothalamus also activates the sympathetic branch of the ANS and the adrenal medulla is triggered via the sympathetic-adrenal medullary pathway, releasing adrenaline
• Role of adrenaline


  Psychological effects include increased anxiety, attention, and alertness. Physical effects include increased blood flow to the brain and skeletal muscles, quick thinking and reactions, and decreased blood flow to the skin, digestive, and immune systems.
• The fight or flight response is maladaptive in most modern situations, as it is frequently triggered by stimuli that cannot be run away from or fought.
• Acute stress, a response to immediate pressures, can be exciting in small amounts and give you focus and energy, but is exhausting and maintained long-term.
• Frequent triggering of the fight or flight response results in chronic stress, which can result in stress-related illness affecting the immune and circulatory systems.
• Localization of function


  Functions such as movement, speech or language, and memory are performed in distinct regions of the brain, they are localized. The opposite view is that the brain acts holistically to perform functions.
• Contralateral control


  Each hemisphere of the brain, right or left, controls the opposite contralateral side of the body, including both motor and sensory pathways and vision of the contralateral visual field.
• Hemispheric lateralization


  Each hemisphere of the brain, right or left, is specialized to perform different functions. Language centers are in the left hemisphere, visuospatial tasks are best performed by the right.
• Motor cortex


  Voluntary muscle motor movements across the body, it's contralateral, located at the back of the frontal lobe, separated from the somatosensory cortex by the central sulcus.
• Somatosensory cortex


  Receives sensory impressions from around the body, it's contralateral, located at the front of the parietal lobe, separated from the motor cortex by the central sulcus.
• Broca's area


  Located in the left frontal lobe only, responsible for speech production. Damage results in motor aphasia, difficulty producing fluent speech.