Topic 8: Endocrine System

• Endocrine gland


  secretes hormones into blood.
• Hormone


  chemical messenger/structure, secreted by endocrine glands, specific to receptor/target cells, regulate and coordinate bodily functions
• Exocrine glands


  Glands that secrete substances outward through a duct
• Hypothalamus


  brain region controlling the pituitary gland

  
• pituitary gland


  Releases hormones that control metabolism and sexual development

  
• pineal gland


  secretes melatonin

  
• Thyroid gland


  produces hormones that regulate metabolism, body heat, and bone growth

  
• Adrenal Glands


  a pair of endocrine glands that sit just above the kidneys and secrete hormones that help arouse the body in times of stress.

  
• Pancreas


  Regulates the level of sugar in the blood

  
• Ovaries and testes


  produce sex hormones
• Circulating hormones


  travel around body through blood
• Local hormones


  neighboring cells without going into the blood stream, can be inactivated quickly
• Regulation of circulating hormones


  complex feedback loops which are influenced by chemical changes in blood(glucagon and insulin), hormones(GHRH causes release of GH) and signals from the nervous system(adrenaline)
• positive loop


  keeps adding up - no homeostasis and an imbalanced result
• negative loop


  a variable triggers a counteractive response - keeps homeostasis
• characteristics of hormones


  - secreted by endocrine glands- Communicate the regulation of bodily functions- Specific to their receptors/target site- Most are carried in the blood
• melatonin

  helps people sleep - secreted by the pineal gland as it regulates sleep and wakefulness
• insulin


  causes cells to take in sugar , when we have too much sugar in our cells - released from pancreas
• adrenaline


  Fight or flight response, heart/breathe rate, blood pressure, muscle strength in stressful situations
• glycogen


  releases sugar into the bloodstream, when we dont have enough sugar such as exercising
• GHRH(growth hormone releasing hormone)


  Stimulates secretion of growth hormone
• the relationship between the hypothalamus and the pituitary gland


  Together responsible for homeostasisHypothalamus controls the pituitary glandPituitary gland is located below the hypothalamusNeurohormones from the hypothalamus directly influence the pituitary gland