the endocrine and nervous systems

• homeostasis - responsible for the regulation and maintenance of the internal environment of the body
• homeostasis regulates:

  1. body temperature
  2. fluids
  3. salts
  4. acids
  5. gases
  6. nutrients
• different control systems in the body:

  1. sensors
  2. control center
  3. communicating systems
  4. targets
• sensors - receptors that are responsible for gathering information about conditions inside and outside of the body
• the skin is made up of many internal sensors that detect changes in the environment
• the human body is made up of sensory neurons which carry impulses to the brain or spinal cord
• brain - the control center of the body which is part of the nervous system. it receives information from the sensors and processes it for the body to function well
• the communicating systems of the body:

  1. nervous system
  2. endocrine system
• target - any organ, tissue, or cell that is responsible for the changes in the activity of the body in response to the message received
• parts of the neuron:

  1. dendrites
  2. cell body
  3. axon
• dendrites - finger-like branched cells present on the end of a neuron. they are the receiving or input portions of a neuron
• cell body - also known as soma, it is the core section of the neuron. it contains genetic information, maintains the neuron's structure, and provides energy to drive activities
• axon - a thin fiber that connects neurons (nerve cells) so that they can communicate. they transmit electrical impulses from muscle and gland cells to the brain
• endocrine system - also known as the "system of checks and balances". it consists of all the glands which secrete hormones directly into the bloodstream to regulate the body
• hormones - chemical substances produced and released by a gland
• major glands of the endocrine system:

  1. hypothalamus
  2. pituitary
  3. adrenal
  4. thyroid
  5. parathyroid
  6. pancreas
  7. thymus, ovaries, and testes
• hypothalamus - connected to the pituitary gland by blood vessels. it is a small gland located at the base of the brain. it regulates activities of the body, metabolism, and reproduction
• hormones released by the hypothalamus:

  1. oxytocin
  2. antidiuretic hormone
• oxytocin - controls muscle contractions of the uterus and milk production
• antidiuretic hormone - increases water uptake in the kidney
• pituitary - stimulates the adrenal and thyroid gland to release specific hormones. it regulates growth and stimulates milk production
• hormones released by the pituitary gland:

  1. adrenocorticotropic hormone
  2. thyroid stimulating hormone
  3. growth hormone
  4. prolactin
• adrenocorticotropic hormone (acth) - stimulates the adrenal gland to release specific hormones
• thyroid stimulating hormone (tsh) - stimulates the thyroid gland to release specific hormones
• growth hormone - regulates the growth of the skeletal system
• prolactin - stimulates milk production in the mammary glands
• adrenal - triggers the "fight or flight" response. it is found just above the kidney.
• hormones released by the adrenal gland:

  1. adrenalin
  2. aldosterone
• adrenalin - it is released into the bloodstream when a person is in dangerous or stressful situations
• aldosterone - increases the uptake of sodium and water in the kidney
• thyroid - located in front of the neck and below the voice box. it regulates the rate of metabolism
• hormones released by the thyroid:

  1. thyroxine
  2. calcitonin
• thyroxine - hormone that contains iodine and regulates the rate of metabolism
• calcitonin - controls calcium levels in the bloodstream
• parathyroid - four tiny glands connected to the back of the thyroid gland
• parathyroid hormone - regulates the minerals in the body-calcium and phosphorus in the bloodstream
• pancreas - located beneath the stomach
• hormones released by the pancreas:

  1. insulin
  2. glucogen
• insulin - controls the level of sugar in the blood
• glucogen - stimulates the liver to convert glycogen to glucose