Communcation By Hormones

Question 1

Where is the pineal gland located and what hormones does it produce?

Answer 1

-in the centre of the brain
-produces melatonin which affects reproductive development and daily cycles

Question 2

Where is the pituitary gland located and what hormones does it produce?

Answer 2

-located in the brain
-produces growth hormone which controls growth of bones and muscles, anti-diuretic hormone which increases reabsorption of water in kidneys and gonadotrophins, which control development of ovaries and testes

Question 3

Where is the hypothalamus located and what hormones does it release

Answer 3

-located in the brain
-production of ADH oxytocin and regulatory hormones

Question 4

Where is the thyroid gland located and what hormones does it produce

Answer 4

-at the base of the neck
-produces thyroxine which controls rate of metabolism and rate that glucose is used up in respiration

Question 5

Where is the adrenal gland located and what hormones does it produce

Answer 5

-located above the kidneys
-produces adrenaline which increases heart and breathing rate and raises blood sugar levels

Question 6

Where is the pancreas located and what hormones are produced

Answer 6

-located between the kidneys
-produces insulin which converts excess glucose into glycogen in the liver, and glucagon which converts glycogen back to glucose in the liver

Question 7

What hormones does the testes produce?

Answer 7

-produces testosterone which controls sperm production and secondary sexual characteristics

Question 8

What hormones do the ovaries produce?

Answer 8

-produces oestrogen, which controls ovulation and secondary sexual characteristics, and progesterone which prepares the uterus lining for receiving an embryo

Question 9

What are the 2 parts of the adrenal gland?

Answer 9

-adrenal cortex (outside)
-adrenal medulla (inside)

Question 10

What 3 hormones does the adrenal cortex release and what are their functions

Answer 10

1) Glucorticoids = regulate metabolism by controlling how the body converts fats, proteins, and carbohydrates to energy. E.g cortisol. Helps regulate blood pressure and cardiovascular function in responses to stress

2) Mineralocorticoids = helps control blood pressure by maintaining balance between salt and water concentrations in the blood and body fluids. It’s release is mediated by signals triggered by the kidneys

3) Androgens = small amounts of male and female sex hormones are released. Their impact is relatively small compared with larger amounts of hormones such as oestrogen and testosterone released by the ovaries or testes after puberty

Question 11

What 2 hormones does the adrenal medulla release and what are their functions

Answer 11

1) Adrenaline = this increases the heart rate sending blood quickly to the muscles and brain. It also rapidly raises blood glucose concentration levels by converting glycogen to glucose in the liver

2) Noadrenaline = this hormone works with adrenaline in response to stress, producing effects such as increased heart rate, widening of pupils widening of air passages in the lungs, and the narrowing of blood vessels in non essential organs (high blood pressure)

Question 12

What is cyclic AMP and what does it do?

Answer 12

-a second messenger
-used for intracellular signal transduction e.g transferring into cells the effects of hormones like glucagon and adrenaline, which cannot pass through the cell membrane
-regulates the effects of adrenaline and glucagon
-it is involved in the activation of protein kinases (enzymes that modify other proteins by chemically adding phosphate groups to them)

Question 13

In the pancreas what do exocrine sections (made up of acinus cells) secrete?

Answer 13

-digestive enzymes

Question 14

In the pancreas what are the 2 groups of cells involved in the regulation of glucose in the Islets on Langerhans?

Answer 14

-Alpha cells produce glucagon
-beta cells produce insulin

Question 15

Describe the change which takes place inside a beta cell which causes the release of insulin when blood glucose levels are high

Answer 15

-potassium ion channels are usually open, and potassium diffuses out of the cell down a concentration gradient. This creates a potential difference of -70mV
-when blood glucose levels are high glucose moves into the cell via facilitated diffusion, where it is then metabolised to produce ATP at the mitochondria
-ATP binds to potassium ion channels causing them to close. This means potassium ions accumulate and the inside of the cell is depolarised
-this change of charge causes the calcium ion channels to open (which are usually closed) allowing calcium ions to diffuse inside the cell
-this then causes the vesicles containing insulin to fuse with the cell membrane, and insulin is released by exocytosis

Question 16

What is diabetes?

Answer 16

-when either your pancreas does not produce enough insulin, or your body cannot effectively respond to the insulin produced, so blood glucose concentration remains high

Question 17

What is the difference between type 1 and type 2 diabetes?

Answer 17

-patients with type 1 diabetes are unable to produce insulin
-patients with type 2 diabetes cannot effectively use insulin and control their blood glucose sugar levels

Question 18

What is the cause of type 1 diabetes?

Answer 18

-the B cells in the islets of Langerhans do not produce insulin
-the exact cause is not known and so at the moment the disease cannot be prevented or cured
-in many cases the condition arises as a result of an autoimmune response where the body’s own immune system attacks the B cells
-it usually begins in childhood

Question 19

What is the cause of type 2 diabetes?

Answer 19

-a persons B cells do not produce enough insulin or the persons body cells do not respond properly to insulin
-this is because the glycoprotein insulin receptor on the cell membranes does not work properly. The cells lose their responsiveness to insulin and therefore do not take up enough glucose, leaving it in the bloodstream
-this is caused largely as a result of excess body weight, physical inactivity, and habitual excessive overeating of carbohydrates

Question 20

What are the symptoms of type 1 and type 2 diabetes

Answer 20

-high blood glucose concentration
-glucose present in urine
-excessive need to urinate
-excessive thirst
-constant hunger
-weight loss
-blurred vision
-tiredness

-type 1 symptoms come on fast whereas type 2 symptoms are less severe and develop slowly.

Question 21

How is type 1 diabetes treated/ managed?

Answer 21

-controlled by regular injections of insulin (not in the mouth as a protein so digested) and is therefore said to be insulin-dependent
-people with the condition have to regularly test their blood glucose concentration by pricking their finger. The drop of blood is analysed by a machine which tells the person their blood glucose concentration, which they can work out the dose of insulin they need to inject, which increases the amount of glucose absorbed by cells and causes glycogenesis to occur

Question 22

How is type 2 diabetes treated/ managed?

Answer 22

-first line of control is to regulate the persons carbohydrate intake through their diet and increasing exercise levels
-in some cases diet and exercise are not enough to control blood glucose concentration so drugs also have to be used, which can stimulate insulin production, or slow down the rate at which the body absorbs glucose from the intestine, and eventually insulin injections

Question 23

Why is it important that blood glucose concentration is regulated?

Answer 23

-important for key metabolic reaction respiration
-if blood glucose is too low you’ll have energy deprivation and cell death
-if blood glucose is too high it will lower the water potential of blood, leading to an osmotic imbalance, water moves out of cells, dehydration of body cells

Question 24

Explain the stem cell treatment for people with diabetes

Answer 24

-beta cells are being replaced in a type 1diabetic patient as they are being destroyed by the immune system
-the treatment VX-880 involves injecting beta cells made from stem cells into a vein that sits near the pancreas, and hopefully they start making the right amount of insulin to keep blood glucose levels in a healthy range
-people having this treatment with type 1 diabetes need to take immunosuppressants as their immune system want to find and destroy any beta cells. The drugs blunt the immune system to prevent it from attacking the transplanted cells
-immunotherapies work to retain the specific parts of the immune system responsible for attacking the pancreas in type 1 diabetes and so don’t have the same side effects

Question 25

Explain how insulin increases glucose uptake by the cells?

Answer 25

-insulin activates the enzyme tyrosine kinase inside the cell
-enzyme 1 phosphorylates the enzymes within the cell and activated them: this increases vesicles containing glucose transporter proteins to move and fuse with the cell surface membrane,, this increases glucose uptake up into the cells,, phosphorylates glucose to hexose bisphosphate (in order to preserve the concentration gradient so glucose will continue to enter the cell)
-activates enzymes (2nd messenger mechanism) to convert glucose to glycogen and fat

Question 26

What is glycogenesis?

Answer 26

Making glycogen from glucose

Question 27

What is glycogenolysis?

Answer 27

Breaking down glycogen

Question 28

What is gluconeogenesis?

Answer 28

Making new glucose from non carbohydrate sources

Question 29

Why are hormones first messengers, and signalling molecules second messengers?

Answer 29

-because they carry the chemical message the first part of the way from the endocrine gland to the receptor on the target cell
-when a hormone binds to its receptor it activates an enzyme in the cell membrane
-the enzyme catalyses the production of a molecule inside the cell called a signalling molecule (signals to other parts of the cell to change how the cell works)

-the signalling molecule is a second messenger because it carries the chemical messenger the second part of the way, from the receptor to other parts of the cell
-second messengers activate a cascade (chain of reactions) inside the cell

Question 30

Explain a second messenger reaction

Answer 30

-the hormone adrenaline is a first messenger
-it binds to specific receptors in the cell membranes of many cells e.g liver cells
-when adrenaline binds it activates an enzyme in the membrane called adenylyl cyclase
-activated adenylyl cyclase catalyses the production of a second messenger called cyclic AMP (cAMP) from ATP
-cAMP activates a cascade of enzyme reactions to make more glucose available to the cell by catalysing the breakdown of glycogen into glucose

Question 31

Explain how insulin lowers blood glucose concentration when it’s too high

Answer 31

-insulin binds to specific receptors on the cell membranes of liver and muscle cells
-it increases its permeability of cell membranes to glucose so the cells take up more glucose
-insulin also activates enzymes that convert glucose into glycogen
-cells are able to store glycogen in their cytoplasm as an energy source
-the process of forming glycogen from glucose is called glycogenesis
-insulin also increases the rate of respiration of glucose, especially in muscle cells

Question 32

Explain how glucagon raises the blood glucose concentration when it’s too low

Answer 32

-glucagon binds to specific receptors on the cell membranes of liver cells
-glucagon activates the enzymes that break down glycogen into glucose
-the process of breaking down glycogen is called glycogenolysis
-glucagon also promotes the formation of glucose from glycerol and amino acids
-the process of forming glucose from non carbohydrates is called gluconeogenesis
-glucagon decreases the rate of respiration of glucose in cells