Hormones

• The hypothalamus secretes hormones that regulate the pituitary gland.
• The anterior pituitary gland produces growth hormone, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, adrenocorticotropic hormone.
• 1.   Thyroid Gland

  a.      Consists of 2 lobes (right and left lobe)

  b.     Within the thyroid gland there are 4 smaller glands (parathyroid gland)

  c.      Main hormone release is Thyroxine which Is made from Iodine and an amino acid.

  d.     Main function is to:

                                                 i.     Maintain body weight by regulating your metabolism

                                                ii.     Maintain body temperature
• 1.   Pineal Gland

  a.      Makes melatonin which is a hormone that regulates the sleep wake cycle.

  b.     Influences sexual development
• 1.   Thalamus

  a.      plays a role in sleep, wakefulness, consciousness, learning and memory.

  b.     Relays sensory and motor signals from various locations in the brain.
• 1.   Parathyroid Gland

  a.      Typically seen at the back of the thyroid gland and there are 4 cells.

  b.     Hormone released is Parathyroid hormone.

  c.      Maintains calcium and phosphate levels in the blood.
• 1.  Thymus Gland

  a.      Located around the trachea

  b.     Secreted the hormone Thymosins

  c.      Produces and develops white blood cells called T Cells (T lymphocytes) They destroy foreign material.
• Adrenal Gland:

  • There are two glands, one on each of the Kidneys, located on the top of them
  • Each gland has an inner gland called the adrenal medulla (dark brown section) and the adrenal cortex (lighter section)
  • Adrenal medulla secretes 2 hormones:
  • Adrenaline: Helps prepare the body for reaction (fight or flight response)
  • Eg- Speaking in front of a class may cause nervousness, leading to increased heart rate and breathing rate due to adrenaline release
  • Noradrenaline: Increases the rate and force of the heartbeat
• • Adrenal cortex secretes 20 different hormones, but you only need to know 2:
  • Aldosterone: Acts on the kidney to reduce sodium and increase potassium in urine
  • Cortisol: Helps with stress, repair damaged cells, promote fat breakdown, control blood sugar levels, and regulate metabolism
• Exocrine function: secretes digestive enzymes into the small intestine through the pancreatic duct
• Endocrine function: within the pancreas are small clusters of cells called "Islets of Langerhans" involved in controlling glucose and secreting insulin
• Insulin:

  • Reduces the amount of glucose in the blood
  • In the liver, insulin converts glucose to glycogen and fat, storing glycogen for later use
• Glucagon:

  • Increases blood sugar levels by breaking down glycogen to glucose in the liver
  • Stimulates the breakdown of fat in the liver
• Gonads are the testes and ovaries, which produce hormones as well as sperm and eggs
• Androgens:

  • Male sex hormone produced in the testes
  • Responsible for the development and maintenance of male sex characteristics
• Oestrogen and Progesterone:

  • Female sex hormones produced in the ovaries
  • Stimulate the growth and maintenance of female sex characteristics
  • Progesterone regulates menstrual cycle and pregnancy up to 3 months
• Synthetic and biosynthetic hormones are used to regulate cell functions and they carry messages as well as being specific, therefore requiring specific receptors in or on the cells to activate particular processes
• Synthetic hormones are produced by either recombinant DNA or chemical manufacturing. They mimic natural hormones and are similar but not identical to human hormones.
• Biosynthetic hormones are produced by other living organisms, bacteria or yeast cells. As the bacteria or yeast contain the gene to produce the hormone, the hormones they produce are more similar, if not identical, to the normal human hormone.
• Negative feedback loop:

  1. stimulus - change in internal or external environment
  2. receptor - detects the change (usually tissue, cell, organ)
  3. modulator - control centre
  4. effector - produces a response usually a muscle or gland
  5. response - modifies the stimulus and brings about appropriate response
  6. feedback - opposite to stimulus
• homeostasis is the process of maintaining a stable internal environment
• hormones are chemical messengers produced and secreted from glands and organs around the body
• enzyme amplification is making more of a particular hormone to articulate more enzymes at one time
• steroid hormones are lipid soluble and diffuse through the cell membrane to combine to receptor proteins inside the nucleus forming a hormone-receptor complex which promotes protein synthesis and is slow acting but long lasting. e.g. oestrogen, testosterone, progesterone, cortisol, aldosterone
• protein and amine hormones are water soluble and cannot pass through the cell membrane. They bind to receptor molecules on the cell membrane which initiates a secondary messenger which activates particular enzymes within the cell. They are fast acting but don't last as long. e.g. insulin, glucagon, growth hormone, thyroid stimulating hormone, oxytocin, luteinizing hormone, prolactin, adrenaline
• paracrines are localised hormones that release hormones within proximity to the target cell
• exocrine glands secrete through ducts onto a surface or into body cavities, such as sweat glands or salivary glands
• endocrine glands are ductless and secrete hormones into extracellular fluid surrounding the gland to target an organ such as the thyroid gland, pituitary glands, adrenal glands
• the hypothalamus is situated inside the brain that regulates basic functions such as body temp, water balance, and heart rate
• The two major roles of the hypothalamus are to produce releasing and inhibiting factors and produce oxytocin and antidiuretic hormone (ADH) which moves along nerve fibres to be stored in the posterior pituitary gland.
• the anterior lobe of the pituitary gland releases

  • follicle stimulating hormone - ovaries for growth of follicles and testes for production of sperm
  • luteinising hormone - ovaries for ovulation and corpus luteum and testes for secretion of testosterone
  • growth hormone - all cells for growth and protein synthesis
  • thyroid stimulating hormone - thyroid gland to release thyroxine
  • adrenocorticotropic hormone - adrenal cortex for the release of cortisol
  • prolactin - mammary glads for milk production
• Posterior lobe of pituitary gland releases:

  • antidiuretic hormone - kidneys for reabsorption of water
  • oxytocin - uterus for contractions during childbirth and mammary glands for release of milk
• The pituitary gland is located just underneath the brain externally and regulates body functions such as growth, metabolism and reproductive cycles. The gland produces, stores and releases hormones that control many other endocrine glands.
• The Anterior pituitary gland produces and releases 6 hormones via stimulation of release or inhibiting factors from the hypothalamus into the bloodstream.
• The posterior pituitary gland releases two hormones which are produced in special nerve cells in the hypothalamus
• The relationship between the hypothalamus and pituitary gland that they are connected via the infundibulum. The hypothalamus controls the pituitary gland.
• Pineal Gland:

  • Makes melatonin which regulates the sleep-wake cycle
  • Influences sexual development
• Thalamus:

  • Plays a role in sleep, wakefulness, consciousness, learning, and memory
  • Relays sensory and motor signals from various locations in the brain
• Thyroid Gland:

  • Consists of 2 lobes (right and left lobe)
  • Contains 4 smaller glands called parathyroid gland
  • Main hormone release is Thyroxine made from Iodine and an amino acid
  • Main functions are to maintain body weight by regulating metabolism and body temperature
• Parathyroid Gland:

  • Typically seen at the back of the thyroid gland with 4 cells
  • Releases Parathyroid hormone
  • Maintains calcium and phosphate levels in the blood