Module 5-Hormones

Question 1

What is the endocrine system made up of?

Answer 1

Endocrine glands-pineal gland, pituitary gland, parathyroid gland, adrenal gland, pancreas, ovary, testis

Question 2

Define endocrine glands

Answer 2

Secrete hormones which are transported in the blood and bind to their target cell causing a response

Question 3

Define hormones

Answer 3

Chemical messengers transported in the blood that have widespread and long lasting effects

Question 4

Examples of hormones

Answer 4

-steroids
-glycoproteins

Question 5

Function of steroid hormones

Answer 5

Lipid soluble and can diffuse across the cell surface membrane into their target cells to bind to a receptor often located in the cytoplasm

Question 6

Function of non steroid hormones

Answer 6

-insoluble in lipids and therefore can’t diffuse across the cell surface membrane.
-instead bind to complementary shaped receptors on the cell surface membrane of the target cell
-the binding to the receptor causes a cascade of responses within the cell

Question 7

Structure and function of adrenal glands

Answer 7

-humans have 2(1 on top of each kidney)
-made up of adrenal cortex and the adrenal medulla surrounded by a capsule
-the cortex and medulla both secret hormones

Question 8

Structure and function of adrenal cortex

Answer 8

-controlled by hormones secreted by the pituitary gland
-responsible for making and secreting steroid hormones
-secrets 3 types of hormones- glucocorticoids (e.g cortisol regulates carb metabolism), mineral corticoids (e.g aldosterone controls ion re absorption in the kidneys), androgens (regulate sexual characteristics and cell growth)

Question 9

Structure and function of adrenal medulla

Answer 9

-controlled by the nervous system
-when the sympathetic nervous system is stimulated it causes the release of adrenaline into the blood (increases HR, blood glucose conc) and noradrenaline (increases HR, dilates pupils, widens airways in lungs, narrows the blood vessels in non essential organs)
-located in the centre of the adrenal gland

Question 10

Structure and function of the pancreas

Answer 10

-gland located behind the stomach
-releases hormones to control BG levels (functioning as an endocrine gland which secrete substances into the blood) and enzymes for digestion (functioning as an exocrine gland that secrete substances into ducts which lead to other tissue)
-most of the pancreas is made up of exocrine tissue called the islets of langerhans that appear much paler than the exocrine cells
-the I of L are made up of alpha cells that secret glucagon and beta cells that secret insulin and glucagon to bring glucose conc back to normal

Question 11

What happens when BGC is too high?

Answer 11

-High blood glucose concentration is detected by the beta cells in the pancreas that are located in the islets of Langerhans.
-Calcium in the beta cell triggers the vesicles containing insulin to move to the cell surface membrane to be secreted by exocytosis.
-beta cells secrete insulin in to the blood
-Insulin binds to receptors on the muscle cell membranes. The muscle cells insert more glucose channel proteins in the cell membrane. This causes the rate of uptake of glucose by muscle cells to increase the rate of respiration in the muscle cells to increase.
-Insulin binds to receptors on the liver cell membranes. The liver cells produce enzymes that convert glucose to glycogen. Glycogen is stored in the liver cells’ cytoplasm(glycogenesis)

Question 12

What happens when BGC is too low?

Answer 12

-Low blood glucose concentration is detected by the alpha (α) cells in the pancreas which are located in the islets of Langerhans
-Alpha cells respond to low blood glucose concentration by secreting a hormone called glucagon into the blood.Glucagon travels in the blood to the liver cells.
-Glucagon binds to receptors on the liver cell membranes. The liver cells produce enzymes that convert glycogen to glucose (glycogenolysis)
-Binding of glucagon to liver cell membranes also causes the release of enzymes that form glucose from glycerol and amino acids (gluconeogenesis)
-Glucagon also slows the respiration rate in cells which slows the rate at which glucose is used up.
-adrenaline is also secreted which binds to receptors on the liver cell membrane.
-Adrenaline induces two reactions in the liver cells: Activation of glycogenolysis (glycogen → glucose). Inhibition of glycogenesis (glucose → glycogen). Adrenaline also promotes secretion of glucagon from the pancreas and inhibits secretion of insulin.

Question 13

How is the second messenger model involved when BGC is too low?

Answer 13

-glucagon binds to glucagon receptors which causes a change in shape to the enzyme adenyl cyclase which activates it
-activated adenyl cyclase enzymes convert ATP into cAMP and cAMP is the second messenger

Question 14

What is glycogenesis and where does it occur?

Answer 14

-converts glucose to glycogen
-occurs in the liver and is catalysed by enzymes there

Question 15

What is glycogenolysis and where does it occur?

Answer 15

-hydrolysis of glycogen to glucose
-occurs in the liver due to second messenger model

Question 16

What is gluconeogenesis?

Answer 16

-creates glucose from other molecules e.g amino acids and glycerol in the liver

Question 17

What is type 1 diabetes?

Answer 17

-chronic health condition where sufferers cannot properly control their blood glucose concentration.
-Type 1 diabetes sufferers cannot produce insulin.

Question 18

What are the causes of type 1 diabetes?

Answer 18

-Type 1 diabetes is caused when the beta cells in the pancreas are attacked by the immune system.
-The beta cells become damaged and can no longer produce insulin.
-Some people are more genetically predisposed to type 1 diabetes than others.
-This type of diabetes normally develops during childhood.

Question 19

What is hyperglycaemia?

Answer 19

People with type 1 diabetes cannot produce insulin to counteract the increased levels of glucose so the blood glucose level remains high.

Question 20

What are treatments of type 1 diabetes?

Answer 20

-Insulin therapy is used to treat type 1 diabetes.
-Insulin is injected regularly during the day or an insulin pump can be used continuously.
-Too much insulin can cause a fall in glucose levels called hypoglycaemia so insulin therapy must be carefully monitored.
-Controlling intake of glucose is also important to prevent a sudden increase in glucose levels.

Question 21

What is type 2 diabetes and when does it develop?

Answer 21

-Type 2 diabetes sufferers don’t produce enough insulin or cannot respond to insulin.
-Type 2 usually develops later in life than type 1.

Question 22

Causes of type 2 diabetes

Answer 22

-Type 2 diabetes is correlated with obesity, lack of exercise, age and family history.
-Type 2 diabetes develops when the beta cells in the pancreas no longer produce enough insulin or when the muscle and liver cells stop responding to insulin.

Question 23

What is hyperglycaemia?

Answer 23

This is when blood glucose levels are higher than the optimum level.

Question 24

What is the treatment of type 2 diabetes?

Answer 24

-Type 2 diabetes is treated by eating a healthy diet and exercising.
-In some cases, medication is used to lower glucose levels.
-In rare cases, insulin injections are used.

Question 25

Future treatments for diabetes?

Answer 25

-Insulin can be produced faster and cheaper using genetically modified (GM) bacteria compared to the traditional method of extracting insulin from the pancreas of pigs and cows. -In this process, the human insulin gene is transferred into plasmids inside E. coli bacteria. -The bacteria then rapidly reproduce and so many copies of the gene are produced rapidly and cheaply. -patients wouldn’t have to wait for pancreas donor -stem cells will probably have to come from embryos which creates ethical issues