homornes

• Homeostasis


  The regulation of conditions inside the body to maintain a stable internal environment in response to changes in both internal and external conditions
• Cells in the body need certain conditions to function properly, such as not being too hot or too cold, not being too acidic or too alkaline, and having a good supply of glucose and water
• The body regulates everything and makes sure that everything is kept around the right levels
• Temperature and glucose levels do fluctuate, but only within small bounds
• The body can maintain its internal environment even if changes are taking place outside of itself
• Automatic control systems


  • Have receptors that detect changes, coordination centers that interpret the changes and decide what to do, and effectors that carry out the changes
• Nervous system


  Sends fast and precise electrical impulses through nerves, allowing for quick responses
• Endocrine system


  Relies on hormones released into the bloodstream, which are slower, longer-lasting, and more generalized than the nervous system
• Negative feedback mechanism


  1. If the level of something gets too high, negative feedback decreases it to return it to normal

  2. If the level of something gets too low, negative feedback increases it to return it to normal
• The overall process of homeostasis is a loop of negative feedback to maintain a stable internal environment
• Endocrine system


  Allows different parts of our body to communicate with each other
• Endocrine system


  Similar job to nervous system, but with lots of differences
• Endocrine system


  • Consists of a series of glands found throughout the body
  • Glands secrete hormones, which are small chemical molecules passed into the blood and spread throughout the body
• Hormones


  Act as signals to trigger certain changes inside cells
• Pituitary gland


  • Produces multiple different hormones
  • Some hormones directly tell the body what to do
  • Some hormones tell other glands to release their own hormones
  • Not actually part of the brain, but attached to it
• Thyroid gland


  • Produces the hormone thyroxine
  • Relates to the rate of our metabolism
  • Plays an important role in growth and development
• Thyroid stimulating hormone (TSH)

  1. Pituitary gland detects low levels of thyroxine

  2. Pituitary gland releases TSH

  3. TSH stimulates the thyroid to produce more thyroxine

  4. Brings the level of thyroxine back up to normal
• Negative feedback


  If thyroxine levels are too low, they are stimulated to rise again, and if they went too high, they are brought back down
• Adrenal glands


  • Produce the hormone adrenaline
  • Normally released during the fight-or-flight response
  • Increases heart rate and gets blood pumping faster
• Pancreas


  • Produces the hormone insulin
  • Helps regulate blood glucose concentrations
• Testes


  • Produce the hormone testosterone
  • Control puberty
  • Produce male gametes (sperm) for reproduction
• Ovaries


  • Produce the hormone estrogen
  • Influence puberty and the menstrual cycle
  • Hold female gametes (egg cells)
• Endocrine system vs. Nervous system

  • Endocrine system uses hormones (small molecules secreted by glands and transported in the blood)
  • Nervous system uses electrical impulses transferred along nerve cells
  • Hormones spread more slowly and have longer-lasting effects
  • Nerve impulses are sent very fast and have short-lasting effects
  • Hormones act more generally and interact with many different cells
  • Nerve impulses are sent to one specific area