Homeostasis

• Homeostasis


  The maintenance of a constant internal environment despite changes in surroundings
• Stimulus response mechanisms help the body to maintain homeostasis

  1. Changes from the normal conditions of the internal/external environments

  2. Regulatory mechanisms to bring it back within the acceptable range
• Order of stimulus response

  1. Stimulus

  2. Receptor

  3. Control centre

  4. Effector

  5. Response
• Stimulus


  Change in environment (internal/external)
• Receptor


  Specialised cells that detect changes
• Control centre


  A specialised organ or part of the body that sends messages (nervous or hormonal)
• Effector


  Part of the body that responds
• Response


  The action that is taken
• Nervous System


  • Transmits signals between the brain and the rest of the body, including internal organs
• Central Nervous System (CNS)


  • Receives messages from the PNS, which is sent to the rest of the body, causing a reaction from the body
• Peripheral Nervous System (PNS)


  • Sends messages about the environment to the CNS and then receives messages from the CNS, which are then taken to the rest of the body
• Parts of the Peripheral Nervous System

  • Somatic NS
  • Sympathetic NS
  • Parasympathetic NS
• Somatic NS


  Carries messages from sensory inputs in the body to the CNS and motor messages from CNS to skeletal systems
• Sympathetic NS


  Prepares the body for action
• Parasympathetic NS


  Calms the body after action
• How messages are communicated via electromagnetic signals

  1. Electrical signal travels along the axon

  2. Electrical signal arrives at the axon terminals

  3. Chemicals cross the gap between the two neurons in the synapse

  4. Receptors on the dendrite trigger a new electrical signal
• Sensory neurons


  Send info from sensory receptors (e.g. skin, eyes, tongue, ears) towards the CNS
• Interneurons


  Send info from sensory neurons to motor neurons, most are found in the CNS
• Motor neurons


  Send info AWAY from the CNS to muscles or glands
• Diagram of a typical nerve cell including: Dendrites, cell body, axon, myelin sheath, axon terminal buttons, receptor, neurotransmitter
• Synapse


  The role is to transfer one neuron to the next, the structure is a small gap at the end of a neuron so info can flow from one neuron to another
• The importance of head protection in relation to impacts of a concussion is that without head protection, important parts can be harmed
• Parts of the brain

  • Frontal lobe
  • Parietal lobe
  • Temporal lobe
  • Occipital lobe
  • Corpus callosum
  • Brain stem
  • Cerebellum
  • Hypothalamus
• Frontal lobe


  Controls higher order thinking, speech and language (control centre)
• Parietal lobe


  Processes sensory info
• Temporal lobe


  Memories are formed here
• Occipital lobe


  Processes visual info like colour, form and motion
• Corpus callosum


  A band of nerve fibres that connect the 2 hemispheres, allows the hemispheres to communicate to each other
• Brain stem


  Controls many subconscious body functions like: breathing and maintaining heart rate
• Cerebellum


  Coordinates fine muscle movements and regulates posture
• Hypothalamus


  Maintains the body's internal environment (homeostasis), its main functions are regulating the release of hormones from various glands in the body, it links the NS to the endocrine system via pituitary gland
• Endocrine System


  • Endocrine glands release hormones into the bloodstream, letting the hormones travel to cells in other parts of the body, the endocrine hormones help control mood, growth, development the way organs work and reproduction
• How messages are communicated via hormones

  From the bloodstream the hormones communicate towards their target cell to bring about a particular change or effect to that cell