5.1.4 Hormonal communication

Question 1

Endocrine system

Name the 8 glands

Answer 1

Consists of a system of endocrine glands which are effectors that release specific hormones

Glands:

Pituitary
Thyroid
Adrenal
Pineal
Thymus 
Pancreas
Testes
Ovaries

Question 2

Pituitary gland

Answer 2

Located at the base of the brain

It releases growth hormones which stimulates the growth of bones and muscle

Also releases ADH and gonadotropin

Question 3

Adrenal gland

Answer 3

Located at the top of the kidneys

Consist of the cortex (outer region) and the medulla (inner region).

Cortex: produces cortisol and aldosterone
Medulla: produces adrenaline and noradrenaline.

Question 4

What is an exocrine system and how is it different from endocrine?

Answer 4

Exocrine: produces ENZYMES via a duct, the duodenum.

Where endocrine releases HORMONES through glands.

Pancreas contains exocrine glandular tissue which releases digestive enzymes via the alkaline pancreatic juice: eg pancreatic amylase, trypsin and pancreatic lipase.

Question 5

Describes the structure and function of the pancreas

Answer 5

Part of the exocrine and endocrine system.

Contains exocrine glandular tissue which releases enzymes
Islet of Langerhans which produces hormones that control blood glucose.

Glucagon released from alpha cells helps to increase blood glucose levels
Insulin produced by beta cells help decrease blood glucose levels

Question 6

Describe how blood glucose concentration is increased (3)

Answer 6

Diet: consuming carbohydrates which are eventually broken down into glucose.

Glycogenolysis: break down of glycogen to release glucose

Gluconeogenesis: breakdown of non-carbohydrate molecules like lipids and amino acids to release glucose

Question 7

Describe the two processes that decrease blood glucose concentration.

Answer 7

Respiration: an increase in physical activity, increases the demand for glucose which is taken in by cells for metabolism

Glycogenesis: the formation of glycogen from glucose, stored in the liver

Question 8

Describe the function of insulin.

Answer 8

Hormone, produced by pancreatic beta cells, that is part of the homeostatic response to high levels of glucose.

All cells except rbc contain insulin receptors which causes a change to the tertiary structure of glucose transport protein channels.

Stimulates the increase of:
Respiration rate of cells
Rate of glycogenesis
Conversion of glucose to lipid

Question 9

Describe the secretion of insulin from a pancreatic beta cell (6)

Answer 9

When glucose levels are normal, ATP sensitive K+ channels are open so K+ diffuse out the cell

An increase in glucose concentration causes glucose to go into the cell via glucose transporter.

Glucose is used for metabolism in the Mitochondrion which releases ATP

ATP produced binds to ATP-sensitive K+ channels, causing them to close. This prevents K+ from leaving the cell.

This increases the charge of the cell from around -70mV to -30mV. This depolarisation causes voltage gated Ca2+ channels to open.

Ca2+ flow down its concentration gradient into the cell which triggers vesicles containing insulin to release insulin via exocytosis.

Question 10

Describe the function of glucagon.

Answer 10

Hormone produced and secreted by pancreatic alpha cells which is responsible for increasing blood glucose concentration.

Only fat and liver cells contain glucagon receptors.

Triggers gluconeogenesis and glucogenolysis.

Question 11

Glycogenolysis

Answer 11

The process of releasing glucose by breaking down glycogen

Occurs as a response to increasing blood glucose concentration

Question 12

Gluconeogenesis

Answer 12

The process of releasing glucose through the breakdown of non-carbohydrate molecules.

Occurs as a response to low blood glucose levels.

Question 13

Glycogenesis

Answer 13

The process of creating glycogen as a storage for glucose in the liver

The is a response to high glucose levels

Question 14

Hormone

Answer 14

Chemical secreted from and endocrine gland that binds to specific receptors on target cells.

Hormones are either steroid or non-steroid

Question 15

Steroid hormones

Answer 15

Lipid soluble hormones that can pass through the membrane.

They bind to receptors located on the cytoplasm or the nucleus.

Binding the nucleus forms a hormone-receptor complex which inhibits/ facilitates the transcription of a gene

Question 16

Non-steroid hormones

Answer 16

Hydrophilic hormones which are unable to pass through the phospholipid bilayer.

They bind to receptors on the cell surface membrane and trigger cascade reactions.

Question 17

Name the different methods of treating diabetes. (5)

Answer 17

Diet: controlling glucose intake

Insulin injection

Pancreas transplant

Injection of pancreatic beta cells (cell transplant)

Stem cell therapy

Question 18

Advantages (5) and disadvantages (5) of using human insulin injections to treat diabetes.

Answer 18

Advs: 
Directly reduces glucose concentration
More effective than pig/animal insulin
Less chance of rejection
Cheap to produce
Less ethical/ moral problems

Disadvs:
Injecting too much can lead to hypoglycaemia 
Injections of painful and annoying
Requires meticulous monitoring of BGC
Might contain side effects.

Question 19

Advantages (2) and disadvantages (4) of doing a pancreatic transplant to treat diabetes.

Answer 19

Advs:
No need for painful injection of insulin.
Permanent cure as body can naturally produce insulin.

Disadvs;
Transplant itself is a greater health risk than diabetes itself.
Immunosuppressant drugs are required for life.
Low number of donors.
Risk of rejection.

Question 20

Advantages (2) and disadvantages (2) of using cell transplant to treat diabetes.

Answer 20

Advs:
No need for insulin injection.
Permanent.

Disadvs:
Very low success rate.
Immunosuppressant drugs used stress Beta cells.

Question 21

Advantages (4) and disadvantages (3) of using stem cells to treat diabetes.

Answer 21

Advs:
Unlimited source of Beta cells.
Low rejection rate.
Permanent.
No need for insulin rejections.

Disadvs:
Cells can grow into tumours.
Ethical issues arise with the use of embryonic cells.
Technology is not ready for it’s use.

Question 22

Acini

Answer 22

Exocrine tissue in the pancreas

Produces and secretes digestive enzymes.

In histology: It appears darkly stained compared to the Islet of Langerhans and is in smaller clusters.

Question 23

Mineralocorticoids

Answer 23

A group of steroid hormones, released from the adrenal cortex, that are responsible for salt and water balance.

Question 24

Glucocorticoids

Answer 24

A group of steroid hormones, released from the adrenal cortex, that are responsible for the metabolism of glucose.

Question 25

Cortisol

Answer 25

A type of glucocorticoid that regulates the metabolism of glucose
It does this by activating gluconeogenesis when blood glucose concentration is low.

Question 26

Aldosterone

Answer 26

The main mineralocorticoids: Controls arterial blood pressure by regulating sodium and potassium ions.

Question 27

Androgens

Answer 27

Sex hormones ,released from the adrenal cortex, that develop the male characteristics

The most prominent example is testosterone.