Hormonal Communication

Question 1

What is the endocrine system?

Answer 1

A communication system

Consisting of hormone secreting glands

Question 2

What are the 2 types of hormone?

Answer 2

Protein based (adrenaline, insulin, glucagon)

Steroid (oestrogen, testosterone)

Question 3

Where do protein hormones bind?

Answer 3

On the cell surface membrane

don’t enter the cell as they aren’t soluble in phospholipid membrane

Question 4

Where steroid hormones act/ bind?

Answer 4

Can enter the cell as they are soluble in the membrane

enter the nucleus and have a direct impact on the DNA

Question 5

Name glands in the endocrine system

Answer 5

Pituitary gland
thyroid gland
thymus
adrenal gland
pancreas
ovaries (females)
testes (males)

Question 6

What are Target cells?

Answer 6

The cell that the hormone is intended to effect

Question 7

What must a target cell have in order for a non-steroid hormone to act?

Answer 7

A specific receptor on the cell membrane that is complementary to the shape of the hormone

Question 8

What is the first messenger?

Answer 8

Something that binds to the cell surface causing a change inside the cell

e.g non-steroid hormones

Question 9

What is the second messenger?

Answer 9

A molecule released inside the cell as a result of the first messenger

stimulates a change in activity of the cell

Question 10

What is activated when a hormone binds to the receptor on the cell surface membrane?

Answer 10

G protien

Question 11

What does the G protein do once it is activated?

Answer 11

Activates an effector molecule

This is normally an enzyme that activates a second messenger

Question 12

What is the most common effector molecule and what second messenger does it form?

Answer 12

Adenyl cyclase

converts ATP to cAMP

Question 13

Where are the adrenal glands found?

Answer 13

Just above the kidneys

Question 14

What are the 2 sections of the adrenal gland?

Answer 14

adrenal cortex

adrenal medulla

Question 15

What are the 3 layers of the adrenal cortex?

Answer 15

Zona glomerulosa - outermost layer, secretes mineralocorticoids

Zona fasciculata - middle layer, secretes glucocorticoids

Zona reticularis - inner layer, secretes precursor to sex hormones

Question 16

What does the zona glomerulosa secrete?

Answer 16

mineralocorticoids

Question 17

What does the zona fasciculata secrete?

Answer 17

glucocorticoids

Question 18

What does the zona reticularis secrete?

Answer 18

Precursor molecules to sex hormones

Question 19

What does the adrenal medulla secrete?

Answer 19

Adrenaline

Question 20

What type of hormones are made by the adrenal cortex? (steroid or non-steroid)

Answer 20

Steroid Hormones

Question 21

How do steroid hormones work?

Answer 21

Pass through cell membrane

Bind with a receptor in the cytoplasm

Hormone-receptor complex passes into the nucleus

binds to receptor on the DNA

Drives production of mRNA which makes a specific protein

Question 22

What is the function of mineralocorticoids?

Answer 22

Control Na+ and K+ concentrations in blood

as a result control blood pressure

Question 23

What is the function of glucocorticoids?

Answer 23

control the metabolism of carbohydrates, fats andf proteins

e.g Cortisol can stimulate the production of glucose from stores

Question 24

What kind of hormone is adrenaline?

Answer 24

non-steroid

Question 25

What are the effects of adrenaline?

Answer 25

``` Relaxes smooth muscle in the bronchioles Increased SV of heart Increased HR Vasoconstriction (increases blood pressure) Stimulates glycogen to glucose conversion Dilating pupils Increases mental awareness Inhibits action of the gut Causing body hair to stand up ```

Question 26

What is an exocrine gland?

Answer 26

A gland that releases hormones through a duct

Question 27

In what way is the pancreas different to most other hormone-secreting organs?

Answer 27

It has both Endocrine and Exocrine functions

Question 28

What is the exocrine function of the pancreas?

Answer 28

Secreting digestive enzymes into the small intestine through the pancreatic duct

Question 29

Where in the pancreas are the digestive enzymes produced?

Answer 29

Acini

Question 30

What is the structure of an Acinus?

Answer 30

exocrine cells that surround a tiny tubule these tubules converge to form intralobular ducts that then converge to form the pancreatic duct

Question 31

What are the three main enzymes in the pancreatic fluid?

Answer 31

Pancreatic amylase Trypsinogen - inactive form of the protease Trypsin Lipase

Question 32

What is the name of the endocrine cells of the pancreas?

Answer 32

Islets of Langerhans

Question 33

Which cells produce insulin?

Answer 33

Beta cells

Question 34

Which cells produce Glucagon?

Answer 34

Alpha Cells

Question 35

How is insulin released from the Beta cells? (long answer)

Answer 35

K+ channels are normally open so K+ can flow out When glucose concentration is too high glucose move into Beta cell It is metabolised into ATP ATP closes K+ channels accumulation of K+ alters the potential difference across membrane This causes Ca2+ channels to open and Ca2+ to rush in Ca2+ causes vesicles containing insulin to bind with cell membrane and are released by exocytosis

Question 36

What is the name given to someone who's blood sugar falls too low?

Answer 36

Hypoglycaemia

Question 37

What is the name given to someone who's blood sugar gets too high?

Answer 37

Hyperglycaemia or Diabetes if it is consistently too high

Question 38

If blood glucose gets too high what will the body do to correct it?

Answer 38

Beta cells in the islets of Langerhans will secrete insulin to convert glucose to glycogen

Question 39

What is the name given to the process where glucose is converted to glycogen?

Answer 39

Glycogenesis

Question 40

Describe the hormone action of insulin on the cells?

Answer 40

Insulin is a non-steroid hormone so binds to surface receptor on the hepatocytes Activates the enzyme tyrosine kinase which phosphorylates inactive enzymes within the cell Cascade of reactions causes glucose transporter proteins to be released allowing more glucose into the cell to be converted to glycogen and fats

Question 41

If blood glucose gets too low, what will the body do to correct it?

Answer 41

Alpha cells in the islets of Langerhans will secrete glucagon to convert glycogen to glucose

Question 42

What is the name given to the process where glycogen is converted to glucose?

Answer 42

glycogenolysis

Question 43

How does Glucagon work?

Answer 43

Glucagon is a non-steroid hormone so binds to surface receptor on the hepatocytes Activates G-protein which activates adenyl cyclase adenyl cyclase converts ATP to cAMP cAMP activates enzyme catalysed reactions causing glycogenolysis

Question 44

Why is blood glucose concentration control an example of negative feedback?

Answer 44

A change is brought about in order to oppose the change in blood glucose If it is too high, insulin will reduce it If it is too low, glucagon will increase it

Question 45

What is Diabetes mellitus?

Answer 45

A condition where the body is unable to control blood glucose concentrations Causes hyperglycaemia after a meal rich in carbohydrates or lipids Causes hypoglycaemia after exercise or fasting

Question 46

What causes Type 1 diabetes?

Answer 46

Autoimmune response in which the immune system attacks and destroys beta cells in the islets of Langerhans Can be post viral

Question 47

How can Type 1 diabetes lead to hypoglycaemia?

Answer 47

Because they cannot produce sufficient insulin they are unable to create glycogen stores when blood glucose is high (e.g after a meal) This means when blood glucose is low there are no stores of glycogen to be hydrolysed and so they become hypoglycaemic

Question 48

What causes Type 2 diabetes?

Answer 48

Where the person is able to produce insulin however this insulin is unable to have an effect on the hepatocytes Blood glucose is almost always too high in Type 2 diabetes

Question 49

What factors can bring an earlier onset of Type 2 diabetes?

Answer 49

``` Obesity Lack of exercise high sugar diet Family history Ethnicity (Asian or Afro-Caribbean) ```

Question 50

What are the treatments for Type 1 diabetes?

Answer 50

Insulin injections (most common) Insulin pump therapy - a small device pumps insulin into the bloodstream at a controlled rate Islet cell transplant - Healthy beta cells transplanted into host Pancreas transplant

Question 51

What are the treatments for type 2 diabetes?

Answer 51

Lifestyle changes e.g: Diet More regular exercise weight loss in severe cases may use insulin injections

Question 52

How has insulin become more available in recent years

Answer 52

Used to be extracted from pigs and cows Produced by a GM bacteria this allows mass production and made insulin a lot cheaper

Question 53

What are the advantages of using insulin from GM bacteria?

Answer 53

Makes Human insulin (as opposed to pig or cow insulin) Less chance of developing a tolerance to insulin Less chance of rejection Lower risk of infection Cheaper to manufacture People are less likely to have moral objections to the way it is produced (religious, vegan)