Biopsychology Part 1

• Made up of billions of neurons. The Brain receives sensory inputs from receptors (E.g. touch) mainly via the spinal cord. The nervous system collects, processes and responds to the environment and coordinates organs and cells in the body
• The two main divisons are the Central and Peripheral nervous system
• Central nervous system = spinal cord and brain
• Peripheral nervous system = nerves that transmit signals

The Brain:

• Main parts of the brain
  • Cerebellum = motion and balance
  • Cerebrum = sensing and thinking
  • Brain stem = automatic actions
  • Cerebral Cortex =
    • Frontal = movement
    • Parietal = touch
    • Temporal = memory
    • Occipital = vision

Peripheral divided into two parts:

• Somatic = Controls voluntary movement in the skeletal muscles. Sensory neurons transmit signals from the body to the brain. Motor neurons transmit signals from the brain to the body
• Autonomic = Crontrols involuntary functions in organs like the heart. Without conscious awareness

Antonomic divided into two parts:

Sympathetic = Controls responses in threatening situstions. Called the fight-or-flight response

Parasympathetic = Returns the body into a normal resting state after the threat has passed. Called the rest-and-digest system

• Refers to the glands in the body that secrete hormones into the bloodstream
• The effect the hormones have on organs influence processes such as growth, metabolism and reproduction
• The Pituitary gland is known as the 'master gland' as it controls the activity of all other glands
• Pituitary gland = Base of brain, affects growth, affects other glands
• Thyroid gland = Lower neck, Regulates heart rate/blood pressure, Thyroxine
• Ovaries and Testes = Physical features, Androgens
• Adrenal glands = Play a role in fight-or-flight, sweat / saliva

Summarise of the fight-or-flight response using the nervous and endocrine system:

• Hypothalamus detects acute stress situation
• Sympathetic branch of autonomatic is activated
• Message sent to the Adrenal Medulla to release Adrenaline and Noradrenaline
• Increase heart rate and blood pressure
• Help to survive dangerous situations by making you active and alert
• Parasympathic activated to rest and digest

Neuron structure:

• Cell body = Which hads a nucleus containing genetic code
• Dendrites = Protrude from the cell body down the neuron. Carries impulses from other neurons to the cell body
• Axon = Carries impulses from the cell body to the terminal that then communicates across the synapse, where it is transmitted to another neuron. This is covered in a fatty layer of myelin sheath which acts as protection and speeds up electrical impulses

Synaptic Transmission:

• This is how neurons communicate with eachother through electrical impulses
• When a neuron is activated, the cell becomes positively charged for a split second.
• This causes an electrical impulse that travels down the axon
• When it reaches the terminal a neurotransmitter is released from sacs called vesicles
• The chemical crosses a gap called a synapse and is taken up by receptors on the dendries of the post-synaptic neuron
• This is then repeated on the next neuron, and so on

Motor Neuron:

• Structure = Short dendrites. Impulses carried away by a long axon
• Location = Cell body inside Central Nervous System, axon on the outside
• Function = Controls muscles and organs (effectors)

Relay Neuron / Interneuron:

• Structure = Short dendrites. Impulse carried by a very short axon
• Location = Inside the Central Nervous System
• Function = Allows motor and sensory neurons to communicate

Sensory Neuron:

• Structure = Long dendrites carry impulses to the cell body
• Location = Cell body outside Central Nervous System, axon on the inside
• Function = Carry signals from receptor to the brain

• Neurotransmitters can be excitatory or inhibition in their action potential

Excitatory

• 'On switches' that increase the likelihood that a signal is sent to the postsynaptic cell
• More likely to fire because it becomes more positively charged
• Excitatory Post-Synaptic Potential
• Dopamine and Noradrenaline are examples of excitatory neurotransmitters

Inhibitory

• 'Off switches' and decrease the likelihood that a signal is sent to the postsynaptic cell
• Less likely to fire because it becomes more negatively
• Inhibitiory Post-Synaptic Potential
• Serotonin and GABA are examples of inhibitory neurotransmitters