Biopsychology

  • Created by: Elina
  • Created on: 24-04-18 17:23
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  • Biopsyhcology
    • Division of nervous sytems
      • Nervous system is broken down into central nervous system (CNS) and peripheral nervous system (PNS).
      • Functions
        • CNS: Comprises of the brain and spinal cord. The CNS is divided into separate areas, each having a different function ranging from controlling thoughts and speech to skills and balance. The function of the CNS is to relay information between the brain and the rest of the body.
        • PNS: Comprises of the nerves outside of the CNS. It connects the CNS to organs, limbs and skin. It relays nerve impulses between the CNS.
        • ANS: Controls involuntary actions we have no control over. i.e. breathing and heart beat.
        • SNS: Receives input  from sense organs and send output to control voluntary actions.
        • P: Has a calming affect on the body and helps the body return tot homeostasis after a period of excitation.
        • S: Has an arousing affect on the body such as preparing for the flight or fight response.
      • Peripheral nervous system is broken down into Autonomic (ANS) and Somatic nervous system.
      • Autonomic nervous system is broken down into Sympathetic (S) and Parasympathetic (P).
    • Structure and Functions of Different types of Neurons
      • Sensory neurons: They have long dendrites and short axons and are unipolar (transmits information only). Function: To carry impulses from sense organs to the CNS.
      • Relay neuron: Many short dendrites and short axons and they are multipolar (receives and transmits information). They also have a myelin sheath. Function: Allow neurons the communicate with one another.
      • Motor neuron: They have long axons and short dendrites and are multipolar. Function: Transmit nerve impulses from CNS to muscles and glands.
    • Process of Synaptic Transmission
      • Features of a synaptic gap
        • A synapse is a junction typically between the axon of one neuron and the dendrites of another.
        • The vesicles in the axon terminal in the pre-synaptic neuron, which are sac filled with neurotransmitters (chemical messengers).
        • The synaptic gap is the tiny gap between 2 neurons.
        • The receptors on the dendrites of the post-synaptic neuron receive the neurotransmitters.
      • 1. Synthesis: Chemicals are transported into the pre-synaptic neuron and are turned into neurotransmitters and packaged into vesicles.
      • 2. Release: In response to an electrical impulse neurotransmitters are released into the synaptic gap. Vesicles travels down to release them into the synaptic gap.
      • 3. Receptor Activation: Neurotransmitter crosses the synaptic gap via diffusion and it binds to  a specific receptor site on the dendrites
      • 4. Inactivation: The neurotransmitters is either taken back into the pre-synaptic (re-uptake) or is broken down into precursor chemicals.
    • Excitation and Inhibition
      • Neurotransmitters released form the pre-synaptic neuron across the synaptic gap and bind to a specific receptor site on the dendrites of a relay neuron. Neuron receives input from many synapses, which are excitatory or inhibitory. This influences the firing of an action potential from the neuron's cell body, which travels along its axons.
      • Excitatory: Has an arousing effect. It increases the chance of an action potential firing.
      • Inhibitory: Has a calming effect. Decreases the chance of and action potential being fired.
      • Summation: Adds up all the excitatory and inhibitory synapses. More excitatory means it does fire the action potential and more inhibitory doesn't fire the action potential.
      • Glutamate (Ex); Necessary for cognition, memory + learning. Increases the activity of other neurotransmitters. High levels over excites neurons until they die, which occurs in neurodegenrative brain disorders like Alzheimer.
      • GABA (In): Prevents excessive levels of other neurotransmitters from influencing neural activity. Regulates cortical functions i.e. vision. Low levels can lead to neurons firing to often, too easily, which has been linked to anxiety.
    • Endocrine System
      • Made up of the pituitary, thyroid, parathyroid, adrenal glands and the pancreas, ovaries (females) and testes (males)
      • Glands produce hormones that have many regulatory functions. It provides a chemical system of communication via the bloodstream with each type of hormone targeting certain organs and tissues.
      • In response to a signal from the brain, hormones are secreted directly into the bloodstream by the glands, where they travel to 'target cells' and stimulate receptors on the surface or inside cells to exert influence. Presence of hormone causes a physiological reaction in the cell, altering it's activity.
    • Flight or Fight Response
      • When we perceive a stressor the brain activate the sympathomedullary pathway (SMP) , which causes the physiological changes in the body to cope with the situation, which is known as the flight or fight response.
      • SMP: A stressor is perceived and threat is detected. The hypothalamus activates the Sympathetic branch of the ANS, Sympathetic nerves transmit the signal from the adrenal gland. The adrenal medulla releases adrenaline and non-adrenaline into the bloodstream. Adrenaline constricts blood vessels in the skin to direct blood to the muscles.
      • Adrenaline prepares the body for action in many ways     --> Increases: Heart Rate (Speeds up blood flow to limbs), Blood Pressure (To get oxygen to limbs), Lung Function (Better transfer of oxygen), Blood Glucose (provides more energy), Pupil Size (Pupils dilate to see surroundings),and Blood Flow To Muscles ( To provide Oxygen to muscles). Decreases: Salivation (To focus energy on limbs) and Digestion (Energy needed for muscles)
      • Parasympathetic response: Once the threat of  the stressor has gone the ANS activates the Parasympathetic branch, which leads to a decrease in the amount of hormones. This opposing, calming effect is known as the rest and digest response, which includes a decrease in heart rate and the return of the digestive processes. Ultimately, parasympathetic activation returns the body to a balanced state -Homeostasis

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