endocrine system

• label

  A) pineal

  B) hypothalamus

  C) pituitary gland

  D) thyroid

  E) parathyroid

  F) thymus

  G) adrenal cortex

  H) kidney

  I) pancreas

  J) testes

  K) ovary

  L) uterus

  
• Hypothalamus

  • Is located in the brain and is responsible for the control of body temperature, water balance (osmoregulation) and secretion of hormones via the pituitary gland
  • It is responsible for control of most of the homeostatic mechanisms that regulate the internal environment of the body (but not blood glucose control)
• Pituitary gland

  • It has 2 parts/lobes, the anterior and posterior.
  • Hormones produced in the hypothalamus are stored in the posterior lobe before secretion
  • The hypothalamus also produces releasing factors that stimulate the anterior lobe to secrete various hormones
• Thyroid

  
  

  • The thyroid is responsible for the regulation of metabolic rate.
  • Metabolism describes all the chemical reactions that take place in the body
  • Metabolic rate is the rate at which the energy stored in our food is transferred by all the metabolic reactions that take part in the body
  • The thyroid is controlled by the releasing factor TRH secreted by the hypothalamus
  • Thyroxine is the main product of the evelopment and metabolid rain growth,
• Parathyroid

  • The parathyroid works with the thyroid to control the levels of calcium in the body
  • Parathyroid hormone (PTH) is secreted by the parathyroid and increases the concentration of calcium ions in the blood while calcitonin, secreted by the thyroid, reduces the concentrations of Calcium ions in the blood
• Adrenal gland

  • They are 2 triangular shaped glands that sit on top of the kidneys
  • They have two parts;
  • The adrenal medulla is the central part and produces the hormone adrenaline that prepares the body to respond to threat or danger - known as the 'fight or flight response.
  • The adrenal cortex produces steroid hormones involved in regulation of metabolism including carbohydrates and mineral ions. These are known as corticosteroids
• Corticosteroids

  • There are 2 classes of corticosteroids
  • Glucocortoids (eg. cortisol) regulate carbohydrate metabolism
  • Mineralocorticoids help regulate the balance of mineral ions such as sodium and potassium
• Ovaries 


  • Release egg cells
  • Produce female sex hormones ostrogen and progesterone which are involved in the regulation of the menstrual cycle
• Testes

  • Produce sperm cells
  • Secrete the male sex hormone testosterone
• Pancreas 


  • The pancreas has an important exocrine function producing digestive enzymes
  • The endocrine function of the pancreas is carried out by the islets of Langerhans which produces the hormones insulin and glucagon
  • These are hormones responsible for the regulation of blood glucose levels.
• The roles of glucose

  • Insulin and glucagon are antagonistic - they work in opposition to each other
  • Insulin reduces blood sugar levels by allowing the glucose into the cells from the blood and to be stored in the liver as glycogen
  • Glucagon increases blood sugar levels by causing the liver to breakdown glycogen stores and releasing glucose back into the blood.
• Dermis

  • Lying below the epidermis is the dermis. This is a layer of connective tissue that helps support the epidermis as well as making the skin elastic.
  • There are many blood vessels and nerve endings in the dermis as well as the hair follicles and exocrine glands (sweat glands and sebaceous glands)
  • In the deepest layer there is areolar tissue and varying amounts of adipose tissue
  • Hair consists of the of the fibrous protein keratin and grows outwards from hair follicles that are lined Sweat duct