Homeostasis

Body systems:

 

  • Cells in multicellular organism function within a hierarchical organisation

  • All systems have an important PURPOSE

 

Tissues: Typically contain a high number of smaller cells rather than fewer large cells --> this arrangement allows for greater functionality and efficiency in performing the tissue's specific roles.

 

  • Blood tissue is an exception in the idea of being glued together by proteins

  • Plants have a gluey pectin between the lamella and cell walls

  • Animals have transmembrane proteins the link between neighbouring cells

 

  • Organs are made up of tissue

  • Organ systems are groups of organs that interact to perform the functions of life

    • Linked: Majority of organs within an organ system are physically linked (e.g. digestive + nervous system)

    • Unlinked: Some of the organs within an organ system are instead, dispersed throughout the body (e.g. endocrine system)

 

Homeostasis:

Homeostasis is maintaining a stable internal balance; maintaining equilibrium to ensure the functions of life can be continued and carried out.

  • Maintained by various physiological mechanisms, like:

    • Body temp

    • Carbon Dioxide

    • Blood pH

    • Blood glucose levels

    • Water balance

  • Homeostasis regulation is achieved through FEEDBACK MECHANISMS (feedback loops) that involve either the nervous system, endocrine system, or combination of both

    • Feedback loops can be POSITIVE or NEGATIVE

Detecting changes in homeostasis:

  1. There will be an external or internal stimulus

    • External stimulus is typically a physical change in the environment (reduction in oxygen, too hot, too cold e.g.)

  2. Will be picked up by a receptor (e.g. if the stimulus is temperature, then the receptors will pick up this information). Receptors can be external (skin e.g.) or internal (blood e.g.)

  3. Signal transduction/communication: Either nervous system sends a message to a brain, OR endocrine system will change your body temperature

    • NOTE: The endocrine system is slower than nervous system

  4. Effector: Usually some sort of muscle (e.g. telling person to take off/put more clothes

  5. Response --> decrease or increase temp e.g. OR it can be behavioural

 

  • Types of receptors:

    • Mechanoreceptors

    • Chemoreceptors

    • Thermoreceptors

    • Photoreceptors