5.1.4 Hormonal Communication

• Homeostasis is the maintenance of our internal environment at a relatively stable level, achieved through negative feedback.
• There are two general types of hormones: peptide hormones, which are hydrophilic and can't pass through the cell surface membrane, and steroid hormones, which are lipid base and can simply diffuse across the membrane.
• Once bound to the receptor, estrogen becomes a hormone receptor complex and can activate or regulate or down regulate transcription of the DNA.
• The adrenal gland is located on top of the kidney and is composed of two parts: the adrenal cortex and the adrenal medulla.
• The adrenal cortex, the outer layer of the adrenal gland, is controlled by hormones sent from the pituitary gland and releases steroid hormones.
• The adrenal cortex releases three types of steroid hormones: glucocorticoids, mineral corticoids, and androgens.
• The adrenal medulla is the middle part of the adrenal gland and it can release peptide hormones when stimulated by the sympathetic nervous system for a stress response.
• Adrenaline can increase the heart rate and blood glucose level, and it can dilate pupils and cause vessels to non-essential organs to constrict slightly.
• The exocrine function of the pancreas involves releasing digestive enzymes, while the endocrine function involves releasing hormones, usually specifically to the bloodstream.
• The pancreatic acini are exocrine tissues that produce and secrete digestive enzymes for digestion and can usually release them into the small intestine in an alkaline environment to do various chemical reactions.
• Insulin and glucagon are both controlled by negative feedback, meaning beta cells and alpha cells can both detect the level of glucose in the bloodstream and release the appropriate hormone to maintain blood glucose level within a normal range.
• Protein kinases are a family of proteins or enzymes that can do a very specific job, protein kinases are enzymes that can phosphorylate other proteins or other enzymes to activate them.
• The method of activation for protein kinases is by adding a phosphate group to them.
• Why is it important to maintain BGL?

  BGL could affect the water potential gradient between cells and the bloodstream:

  If it's too high, then more water leaves the cells by osmosis, causing them to be dehydrated.

  If it's too low, then more water enters the cells by osmosis, and in the worst case, causing them to burst.

  In both cases, they may disrupt concentrations of other chemicals in the cells, affecting various reactions.

  If the body is unable to regulate BGL, this condition is called diabetes.
• Interventions in the control of blood glucose levels

  • insulin injection
  • regular cardiovascular exercise
  • glucagon injection
• Describe how adrenaline binds to cardiac cells.

  • binds to receptor in cell surface/ plasma membrane
  • glycoprotein on calls complementary to specific receptors
• Functions of adrenaline

  • increased heart rate
  • increased blood glucose to muscles
  • increased glycogenolysis
  • pupil dialation so increased light in eyes, can see in dark
  • decreased blood flow to gut
  • increased blood pressure
  • dilation of bronchioles
  • increased air flow to alveoli
  • increased breathing rate
• functions of noradrenaline

  • increased heart rate
  • increased blood pressure
  • stimulates glycogenosis
  • fight/ flight response
• functions of androgens

  • regulation of sexual characteristics in cell growth
  • increased in menopause
• function or cortisol/ corticosterone/ glucocorticoids

  • regulation of metabolism
  • stimulates glycogenolysis 

  • reduces inflammation
  • regulates blood pressure
• functions of aldosterone

  • Na+, K+ ions reabsorption in kidneys and concentration in blood
  • water reabsorption
  • control of blood pressure
  • found in adrenal cortex
• What is the normal range of BGL?

  90mg 100cm^-3
• If blood glucose is too high..

  • detected by beta cells in the islet of langerhans in the pancreas
  • insulin hormone secreted into blood
  • target cells are hepatocytes in liver
  • insulin binds to receptors on the plasma membrane of the live/muscle cells
  • more glucose enters cells
  • glycogenesis occurs
  • more glucose converted into fats
  • increased metabolic rate (more respiration occurring)
  • bg levels fall
• If BG is too low...

  • detected by alpha cells in the islet of langerhans in the pancreas
  • glucagon hormone secreted
  • targeted to hepatocytes in liver
  • glycogenolysis occurs
  • more fatty acids used in respiration
  • gluconeogenesis occurs
  • BG conc rises
• How is the release of insulin regulated?

  • Beta cell plasma membranes contain K+(normally open, diffuse out making inside more negative than outside) and Ca2+(normally closed) channels
  • BG too high, glucose diffuse in via facilitated diffusion, used in respiration producing ATP causing K+ channels to close, no longer diffusing PD becoming less negative
  • Ca2+ channels open causing insulin containing vesicles to fuse with plasma membrane and release insulin
• What is diabetes mellitus?

  • BG levels fluctuate due to eating and exercise, body can no longer control levels
  • can lead to high BP/ low BP causing dizziness, fainting and organ failure
• What's hyperglycaemia?

  BG levels too high
• Whats hypoglycaemia?

  BG levels too low
• What's type 1 diabetes?

  • insulin-dependent diabetes
  • body no longer produces insulin, beta cells not functioning correctly and can't score excess glucose and glycogen
  • result of autoimmune disease; body destroys beta cells, genetic but can be triggered by a virus or environmental factor
• What is type 2 diabetes?

  • starts later in life due to obesity/aging, non-insulin dependent
  • body not responding to insulin properly, not produced enough because glycoprotein receptor for insulin ineffective
  • earlier onset caused by; obesity, physical inactivity, high BP, asian/afro decent, family history, age, males, excessive alcohol intake
• Explain how blocking Ca2+ channels could inhibit insulin

  • Ca2+ ions do not enter cells
  • no/ less movement of vesicles towards/ fuse membrane
  • no/ less exocytosis
• Ways to treat diabetes

  • eating less sugars in diet
  • regular exercise
  • insulin injection (type one) genetically engineered
  • stem cells: isolate cells from patient grow in dish, treat cells with reprogramming factors, wait a few weeks, pluripotent stem cells, change culture conditions yo stimulate cells to differentiate to pancreatic beta cells (type one)
• Drawing cells from photomicrograph

  • 3 cells next to each other and clear continuous lines, no shading no ragged lines
  • more than 50% area used
  • label lines with a ruler to correct feature with no arrow heads
  • at least three labels
• Why is standard deviation useful?

  • less effected by the anomalous value
  • takes into account every value of data
• Insulin treatments from animals, such as dogs and cows, have been used in the past, but they need to be purified and there is a risk of allergic reaction.
• Insulin treatments from humans, including current gene therapy, have high purity, less risk of allergic reaction, lower production cost, and overcome religious/ethical debate.
• Smart pens and pumps that can be monitored by apps are used in current insulin treatments from humans.
• People may be persuaded from previous regimes and may not understand the new treatments.
• Side effects of pumps include lumps forming under the skin.
• Other potential treatments for type one diabetes include the transplant of pancreas/ islets and pancreatic stem cells.