Endocrine system

• What is the endocrine system?

  It involves a series of endocrine glands that secrete hormones into the blood. These act as chemical messengers, as they are transported around the body in the blood and act on target cells or organs. This regulates bodily functions.
• What is the endocrine system involved in?

  • Regulation of growth and development

  • Regulation of the reproductive system

  • Homeostasis: the regulation of the internal environment of the body.
• What are the components of the endocrine system?

  • Hypothalamus

  • Pituitary gland

  • Thyroid and parathyroid

  • Adrenals

  • Ovaries

  • Testes

  • Pancreas
• What is the location and function of the hypothalamus?

  • It’s located in the base of the brain.

  • It is responsible for the control of body temperature, water balance, BP and secretion of hormones.

  • It secretes hormones that stimulate or suppress the release of a hormone in the pituitary gland.
• What is the location and function of the pituitary gland?

  • It is divided into the anterior and posterior parts or lobes. 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.

  • It controls the functions of other glands.
• What is the location and function of the thyroid and parathyroid gland?

  • In the front of the neck.

  • Thyroid: responsible for the regulation of metabolic rate. It is controlled by the releasing factor TRH, secreted by the hypothalamus.

  • 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, which is secreted by the thyroid, reduces the concentration of calcium ions in the blood.
• What is the location and function of the adrenal glands?

  • They’re located at the top of each kidney and have two parts:

  Adrenal medulla

  • Adrenal cortex
• What is the role of the adrenal medulla?

  It is the central part of the adrenal half and produces the hormone adrenaline that prepares the body to respond to threat or danger. This is known as fight or flight.
• What is the role of the adrenal cortex?

  It produces several steroid hormones involved in the regulation of different aspects of metabolism including carbohydrates and mineral ions.

  The name for these hormones is corticosteroids.
• What is the location and function of the ovaries?

  • They’re located at both sides of the uterus.

  • Release egg cells.

  • Produce female sex hormones like oestrogen and progesterone, which are involved in the regulation of the menstrual cycle.
• What is the location and function of the testes?

  • They’re underneath the penis, enclosed in the scrotum.

  • They secrete the male sex hormone testosterone and produce sperm.
• What is the location and function of the pancreas?

  • It’s located at the back of the abdomen, behind the stomach.

  • It produces digestive enzymes. It endocrine function is carried out by the islets of Langerhans which produce the hormones insulin and glucagon. These regulate blood glucose concentration.
• What is the hormone thyroxine secreted by and what is its function?

  • It’s secreted by the thyroid.

  • It acts on most body cells to regulate metabolism, temperature, heart rate and growth and tissue development.
• What is the hormone cortisol secreted by and what is its function?

  • It’s secreted by the adrenal cortex.

  • It is produced in response to stress. It acts on the liver and muscle cells and increases the blood glucose concentration.
• What is the hormone oestrogen secreted by and what is its function?

  • It’s secreted by the ovaries.

  • It acts on the pituitary gland and the uterus and is involved in the regulation of the menstrual cycle, supports the growth of the uterine lining and maintains bone density.
• What is the hormone testosterone secreted by and what is its function?

  • It’s secreted by the testes.

  • It acts on muscle and bone cells, the anabolic action of testosterone increases the muscle mass and bones density.

  • It acts on sex organs, the androgenic action of testosterone stimulates the development of the male sex organs and secondary sexual characteristic like facial hair.

  • It also required for the production of sperm cells.
• What is the hormone gastrin secreted by and what is its function?

  • It’s secreted by the gastric cells of the stomach lining.• It acts on the stomach and has several actions in digestion involving the stomach and small intestine. It stimulates the release of gastric acid to aid digestion.
• What is the growth hormone (GH) secreted by and what is its function?

  • It’s secreted by the pituitary gland.

  • Most body cells respond to GH which is responsible for normal growth during infancy and childhood. Therefore it stimulates cell reproduction and regeneration.
• What is the follicle-stimulating hormone (FSH) secreted by and what is its function?

  • It’s secreted by the pituitary gland.

  • It acts in the ovaries, stimulating the growth and development of the egg follicle during the first half of the menstrual cycle. The egg follicles are in the ovaries and contain the developing egg cell. It also stimulates the production of sperm.
• What happens if blood glucose levels are too high?

  • Beta cells in the pancreas detect a rise in glucose levels and release insulin.

  • Insulin causes glucose levels to fall by storing glucose as glycogen in the liver.

  • There is now a normal blood glucose concentration.

  • Insulin production is then inhibited.

  (This continues as a constant cycle, as it is a negative feedback loop).
• What happens if blood glucose levels are too low?

  • Alpha cells in the pancreas detect a fall in glucose levels and release glucagon.

  • Glucagon causes glucose levels to rise as it causes the liver to release stored glucose.

  • A normal glucose concentration.

  • Glucagon production is inhibited.

  (This continues as a constant cycle, as it is a negative feedback loop).
• How the hypothalamus controls the amount of water lost in the urine

  1. When water potential is too LOW

  2. Osmoreceptors in hypothalamus detect this

  3. Hypothalamus stimulates release of ADH from posterior pituitary gland

  4. ADH causes more water to be reabsorbed by kidney

  5. Water potential rises to normal level
• How the hypothalamus controls the amount of water lost in the urine

  1. When water potential is too HIGH

  2. Osmoreceptors in hypothalamus detect this

  3. Hypothalamus inhibits release of ADH

  4. Less water is reabsorbed by kidney

  5. Water potential reduced to normal level
• ADH (antidiuretic hormone)

  Hormone that controls the amount of water lost in urine
• What happens if body temperature is too high?

  • Sweating to release heat via evaporation.

  • Vasodilation: vessels dialyse to increase heat loss.

  • Shivering is reduced to conserve energy and decrease heat production.

  • Metabolic rate decreases to reduce heat.
• What happens if body temperature is too low?

  • Vasoconstriction: vessels constrict to minimise heat loss.

  • Shivering: muscles generate heat through involuntary contractions.

  • Metabolism increases causes metabolic processes to accelerate, to generate heat.
• What happens if blood osmolarity is too high?

  • Dehydration

  • Impaired cellular function

  • kidney damage

  • thirst
• What is type 1 diabetes?

  The destruction of the beta cells in the pancreas that normally produce insulin, making the body unable to respond to an increased in blood glucose concentration.

  This is because the pancreas makes little to no insulin.
• What causes type 1 diabetes?

  The bodies immune system mistakenly destroying beta cells, which are insulin producing cells (islet cells) in the pancreas.
• How do insulin injections treat type 1 diabetes?


  Since your pancreas no longer makes insulin, you must inject it to control your blood glucose level.

  It is injected subcutaneously multiple times a day, in your belly, the front of your thighs and the back of upper arms.
• How do insulin pumps treat type 1 diabetes?

  It consists of an electronic device that delivers insulin through a cannula under the skin.

  You attach the pump to your skin and insulin goes into your body through the tiny tube.

  It will usually deliver small amounts for insulin all the time, but can also deliver a larger dose, if glucose levels are too high.

  This needs to be replaced every 2-3 days and moved to a different part of the body.
• How does a change in diet and exercise help manage type 1 diabetes?

  It helps to manage blood sugar levels.
• How does type 1 diabetes affect an individual?

  Diabetes is a life long condition, which places a lot of responsibility upon the individual as they have to constantly manage their health and be more conscious than other may need to be. This has the potential to develop into anxiety.
• What is type 2 diabetes?

  This is when your cells have insulin resistance, so your pancreas makes more insulin to try get the cells to respond.

  Eventually, your pancreas cannot keep up, and your blood sugar rises setting the stage for pre-diabetes and type 2.
• What causes type 2 diabetes?

  • being overweight

  • inactive

  • family history
• What are the symptoms of type 2 diabetes?

  • urinating more

  • thirst

  • tiredness

  • weight loss

  • cuts and wounds take longer to heal

  • blurred vision
• What are the treatments for type 2 diabetes and gestational diabetes?

  • eating well

  • moving more

  • metformin tablet

  • insulin to lower blood sugar

  • weight loss surgery
• What lifestyle changes can you make to manage type 2 diabetes?

  • Eating a balanced diet

  • staying active

  • managing stress

  • getting enough sleep
• How does metformin work to manage type 2 diabetes?

  It decreases the amount of sugar produced by the liver, making the cells more responsive to insulin.

  This is a tablet.
• What is gestational diabetes?

  This is similar to type 2.

  It occurs in about 2-10% of all pregnancies.

  Blood glucose concentrations are elevated because the pancreas can’t produce enough insulin to meet the extra needs of the body during pregnancy.

  It usually disappears after giving birth.