The Nervous And Endocrine Systems

• Nervous system


  Specialised network of cells in the human body and is our primary internal communication system
• Main functions of the nervous system

  - To collect, process and respond to information in the environment.

  - To co-ordinate the working of different organs and cells in the body.
• Central Nervous System (CNS)


  Made up of the brain and spinal cord
• Brain


  Centre of all conscious awareness. Brain's outer layer, the cerebral cortex, is highly developed in humans and is what distinguishes our higher mental functions from those of animals; divided into two hemispheres
• Spinal cord


  Extension of the brain, responsible for reflex actions such as pulling your hand away from a hot plate. Passes messages to and from the brain and connects nerves to the PNS
• The Peripheral Nervous System (PNS)


  Transmits messages via millions of neurons to and from the CNS. Subdivided into two components
• Autonomic nervous system (ANS)


  Governs the vital internal activities of the human body, including heart rate, breathing, digestion, salivation, perspiration, urination, and sexual arousal
• Somatic nervous system (SNS)


  Controls muscle movements and receives information from sensory receptors
• The Endocrine System


  Works alongside nervous system to control vital functions in the body. Acts more slowly than nervous system but has very widespread and powerful effects
• Glands and hormones


  Various glands produce hormones, hormones are secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone. Most hormones affect cells in several organs throughout the entire body
• Example of hormones


  Thyroid gland produces thyroxine affecting cells in the heart (increasing heart rate) and affects cells throughout the body increasing the metabolic rates
• Main endocrine gland


  Pituitary gland which is the 'master gland' controlling the release of hormones from all of the endocrine glands in the body
• Main endocrine glands in the body

  Hypothalamus, pituitary, thyroid, parathyroid, adrenals, pancreas, ovaries, testes
• Endocrine and ANS working together: fight/flight


  Endocrine and ANS work in parallel often with one another- stressful event for example
• Stress


  When stressor is perceived, the hypothalamus triggers activity in the sympathetic branch of the ANS. ANS changes from its normal state, parasympathetic state, to its physiologically aroused sympathetic state
• Adrenaline


  The stress hormone adrenaline is released from the adrenal medulla into the bloodstream: increases heart rate and overall triggers physiological changes in the body necessary to fight/flight
• When the threat is over


  Once the threat has passed, the parasympathetic nervous system returns the body to its resting state: acts as a 'brake' and reduces the activities of the body that were increased by the actions of the sympathetic branch- called the rest and digest response
• Sympathetic state


  Increases heart rate , increases breathing rate ,dilates pupils, inhibits digestion, inhibits saliva production and contracts rectum
• Parasympathetic state


  Decreases heart rate, decreases breathing rate, constricts pupils, stimulates digestion, stimulates saliva production and relaxes rectum