Biological approach 2

• What are the two main divisions of the nervous system?

  Peripheral nervous system and central nervous system
• What is the role of the spinal cord?

  It is responsible for reflex actions and passes messages to and from the brain
• What percentage of the brain's total mass is made up of the cerebrum?

  85%
• What is the outer layer of the cerebrum called?

  Cerebral cortex This is highly developed and distinguishes our higher order mental functions
• What are the two sub-parts of the autonomic nervous system?

  • Sympathetic nervous system
  • Parasympathetic nervous system
• What does the sympathetic state mean in fight or flight?

  • Increases heart rate
  • Dilates pupils
  • Inhibits saliva production
  • Contracts rectum
  • Inhibits digestion
• What does parasympathetic state mean in fight or flight?

  • Decreases heart rate
  • Decreases breathing rate
  • Constricts pupils
  • Stimulates saliva production
  • Relaxes rectum
  • Stimulates digestion
• What does the spinal cord do?

  Extension of the brain, it is responsible for reflex actions. Passes messages to and from the brain
• What does the frontal lobe do?

  Functions include - Speech, thought and language
• What does the temporal lobe do?

  Function include - Hearing and memory

  Found at the sides
• What does the parietal lobe do?

  Functions include - Sensory info such as touch, temperature and pain

  Found in the back/middle between frontal and occipital lobe
• What does the occipital lobe do?

  Functions include - processes visual info

  Found at the back
• What does the Peripheral Nervous System do?

  The Peripheral Nervous system transmits messages via neurons to and from the CNS

  Made up of the Autonomic Nervous System and the Somatic Nervous System
• What does the endocrine system do relating to glands?

  • Works alongside the nervous system to control vital functions in the body through hormones
  • Slower than the nervous system
  • Pituitary gland – key endocrine gland found in the brain- known as the ‘master gland’ – it controls the release of hormones from all other endocrine glands
• What does the endocrine system do relating to hormones?

  • Move through the bloodstream
  • affect any cell in the body that has a receptor for that particular hormone
  • E.g. thyroxine increases metabolic rates which affects growth rate
• What does the endocrine system do in terms of fight or flight?

  • The endocrine system and the autonomic nervous system work in parallel
  • A stressor is perceived by the hypothalamus activates the pituitary gland– the sympathetic nervous system is now aroused
  • Adrenaline is released from the adrenal medulla into the bloodstream
  • This hormone causes changes e.g. increased heart rate
  • Once the threat has passed, the parasympathetic nervous system takes over –returns the body to its resting state
• How many neurons are in the body and where are they mostly found? 


  • 100 billion nerve cells (neurons) in the human nervous system
  • 80% of neurons are in the brain
• What is a synapse ?

  • extremely tiny gap separating neurons
• How do signals move across neurons?

  • Signals within the neurons are transmitted electronically
  • the signals between neurons and transmitted chemically
• How do signals move across the synapse?

  • A nerve impulse reaches the end of one neuron, a neurotransmitter (chemical ) is released
  • Neurotransmitters carry signals between neurons across the synapse
• What is an excitatory neurotransmitter?

  Triggers nerve impulses that stimulate brain action e.g. Dopamine
• What is an inhibitory neurotransmitter?

  Inhibit nerve impulses in order to calm the brain and balance mood e.g serotonin
• What are sensory neurons?

  carry messages from the peripheral nervous system to the central nervous system

  Long dendrites and short axons
• What are relay neurons ?

  Connect the sensory neurons to the motor neurons or other relay neurons

  Short dendrites and short axons
• What are motor neurons ?

  Connect the central nervous system to effectors

  Short dendrites and long axons