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57 Cards in this Set

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What is the endocrine system?

A system that uses blood to carry signals using endocrine and exocrine glands.


Define hormone

Chemicals secreted from an endocrine gland that act as messengers travelling through the blood plasma to carry signals to a specific target organ or tissue.


Define target tissue

A group of cells that contain specific receptors that are complementary to the shape of a hormone molecule.


What is the difference between an Endocrine and Exocrine gland?

An endocrine gland secretes hormones directly into the blood and is ductless.

An exocrine gland secretes molecules through a duct and not directly into the blood.


What is the difference between steroid hormones and protein/peptide hormones?

Steroid hormones are lipid soluble and so pass through the plasma membrane into the cytoplasm where it binds to receptors and has a direct effect on DNA.

Protein/peptide hormones are insoluble in the phospholipid membrane so bind to receptors in the plasma membrane and do not enter the cell.


Where do mammalian hormones travel through?

The blood plasma


How are mammalian hormones removed from the blood plasma?

Enzymes break them down.

Adrenaline - first and second messengers

What is Adrenaline?

A hormone secreted by the adrenal gland in response to fear, stress or excitement.

Adrenaline - first and second messengers

Why may second messengers be necessary?

Apply this to adrenaline pls

Because protein hormones cannot enter the cell.

Adrenaline is an amino acid derivative so is not lipid soluble so it cannot enter the target cell SO it needs to cause an effect inside the cell without entering it.

Adrenaline - first and second messengers

What is

a) the first messenger

b) the second messenger

a) the hormone that transmits a signal around the body

b) cAMp, which transmits a signal inside a cell - a molecule that is affected by the binding of a first messenger to a receptor.

Adrenaline - first and second messengers

Outline the rough events of the activation of a second messenger

1) The hormone is secreted by an endocrine gland

2) The hormone binds to receptors on the plasma membrane of the target cell that have a complementary shape

3) This activates the second messenger within the cell

4) The second messenger causes an effect in the cell

Adrenaline - first and second messengers

Outline the processes that follow the secretion of Adrenaline

1) Adrenaline binds to the specific receptor with a complementary shape on the cell surface membrane

2) This activates the enzyme andenyl cyclase

3) Adenyl cyclase converts ATP to cAMP

4) cAMP causes an effect in the cell by activating enzyme action

Adrenaline - first and second messengers

How does cAMP result in the break-down of glycogen?

1) cAMP binds to protein kinase which becomes activated

2) Protein kinase activates the enzyme glycogen phosphorylase kinase

3) Glycogen phosphorylase kinase binds to glycogen phosphorlyase

4) Glycogen phosphorlyase breaks down glycogen to glucose

Adrenaline - first and second messengers

Where are the adrenal glands?

Just above the kidneys

Adrenaline - first and second messengers

What is the function of the adrenal medulla?

Cells in the medulla manufacture and release the hormone adrenaline in response to stress such as pain and shock.

Adrenaline - first and second messengers

What are the effects of adrenaline?

1) Relaxes smooth muscle in bronchioles

2) Increases stroke volume of the heart

3) inhibits action of the gut

4) dilates pupils

5) causes vasoconstriction to raise blood pressure

6) stimulate conversion of glycogen -> glucose

7) causes body hair to erect

8) increases mental awareness

Adrenaline - first and second messengers

What is the function of the adrenal cortex

Uses cholesterol to produce some steroid hormones which...

-help control the concentrations of sodium and potassium in the blood

-help control the metabolism of carbohydrates and proteins in the liver

Pancreas and glucose regulation

What type of gland is the Pancreas?

An exocrine and endocrine gland.

Pancreas and glucose regulation

What is the exocrine function of the pancreas?

The secretion of pancreatic juice into ducts.

Pancreas and glucose regulation

What does the pancreatic juice contain?

Trypsin, Amylase and Lipase.

Pancreas and glucose regulation

What is the function of

a) Trypsin

b) Lipase

c) Amylase

a) Catalyses the hydrolysis of proteins to polypeptides

b) Catalyses the hydrolysis of lipids to fatty acids and glycerol

c) Catalyses the hydrolysis of Starch to maltose

Pancreas and glucose regulation

What is the endocrine function of the Pancreas?

The Islets of Langerhans contian alpha and beta cells which manufacture secrete hormones directly into the blood. (glucagon and insulin)

Pancreas and glucose regulation

What hormone do

a) Alpha cells secrete

b) Beta cells secrete?

and what are the target cells?

a) Glycogen - hepatocytes

b) Insulin - hepatocytes + muscle cells

Pancreas and glucose regulation

Draw the Islet of Langerhans

Pancreas and glucose regulation

Draw the gross structure of the pancreas

Pancreas and glucose regulation

How are carbohydrates stored?

As glucose.

Pancreas and glucose regulation

How is glucose stored?

As glycogen.

Pancreas and glucose regulation

What happens if blood glucose rises

a) too high?

b) too low?

a) The water potential of the blood becomes lower than body cells so they lose water to the blood by osmosis

b) cells run out of glucose for respiration so are unable to carry out normal activites

Pancreas and glucose regulation

What happens in the pancreas in response to eating a meal high in carbohydrates?

1) The small intestine absorbs the food and it enters the blood

2) As blood passes through the pancreas, alpha and beta cells in the Islet of Langerhans detect the increase in blood glucose

3) Alpha cells stop the secretion of glUcogen

4) Beta cells increase the secretion of insulin

5) Insulin is transported around the body in the blood plasma

Pancreas and glucose regulation

How does Insulin affect cells?


Glucose can only enter cells by transporter proteins which are normally in the cytoplasm. When Insulin is detected, the transporters move to the plasma membrane, forming channels which allow glucose to enter cells, leaving the blood.


When Insulin binds to the complementary receptors in the plasma membrane of a liver cell, it activates the enzyme glucokinase. It then phosphorylates glucose - phosphorylated glucose cannot leave the cell through transport proteins.


The arrival of Insulin also activates phosphorofructokinase and glycogen synthase which both cause glucose to form glycosidic bonds to form glycogen

4) more glucose is used in respiration

5) more glucose is converted to fats

Pancreas and glucose regulation

How does glUcogen affect cells?


When glycogen binds to the receptors in liver cell plasma membranes, it activates enzymes which catalyse the hydrolysis of glycogen to glucose. Glucose can then move out of the liver cell, into the blood by facilitated diffusion through transport proteins


GlUcogen triggers the production of glucose from other substances - conversion of amino acids and lipids - inside liver cells.

3) More fatty acids are used in respiration

Pancreas and glucose regulation

What type of mechanism is the pancreas' response to a rise/fall in blood glucose levels?

Why does blood glucose concentration not stay constant?

Negative feedback! You ding dong

There is a time delay between the change in blood glucose and the actions to correct it.

Pancreas and glucose regulation

Describe the events that control the secretition of Insulin

1) Cell membranes of Beta cells contain Calcium and potassium ion channels

2) Potassium ions are usually open, Calcium closed. Potassium ions diffuse out of the cell, making the inside of the cell more negative than the outside, -70mV

3) When glucose levels are high, glucose molecules diffuse into the cell

4) As it enters, it is phosphorylated by GLUCOKINASE and metabolised to form ATP

5) The presence of ATP causes potassium ion channels to close

6) Potassium ions can no longer diffuse out, so it becomes less negatively charged inside

7) The change in potential difference causes calcium ion channels to open

8)Calcium ions enter the cell and cause vesicles containing insulin to move to the cell surface membrane and fuse with it, releasing insulin by exocytosis.


What is the full name for Diabetes?

What is diabetes?

Diabetes Mellitus

A disease in which blood glucose concentrations cannot be controlled effectively


What is Type 1 Diabetes?


Body is unable to manufacture sufficient insulin and cannot store excess glucose as glycogen.

so after a meal high in carbohydrates, blood glucose levels soar.

It typically arises in early life.

It is also thought that a persons immune system attacks its own beta cells.


What is Type 2 Diabetes?


It typically arises later in life.

The pancreas does secrete insulin, but liver cells and other target organs do not respond adequately.


What are the risk factors for Diabetes?

* High body weight - BMI over 27 ~(BMI is (weight kg / height m)^2 )

* May be genetic

* Lack of exercise

* Diet high in sugars


List some symptoms of Diabetes

Tiredness, Thirst, Blurred vision, Feeling unwell


What is

a) hypercglycemia?

b) hypoglycemia?

a) High blood glucose concentration.

b) low blood concentration


Why does a person with hyperglycemia feel thirstly?

If there is a high concentration of glucose in the blood in the tissue fluid, water leaves cells by osmosis into the tissue fluid. This is detected by the hypothalamus which sends nerve impulses to tell them they are thirsty.


What is ketoacidosis?

Ketoacidosis is caused by the presence of ketone bodies which are produced from fatty acids in the liver, and can be used as respiratory substrates. High concentrations of ketones can be dangerous.


Why does a person with hypoglycemia feel tired?

Cells do not have enough glucose - can be solved by eating something sugary.


How can Diabetes be treated?

TYPE 1 - Insulin injections. Blood glucose conc is monitored and correct dose of insulin is given to ensure blood glucose remains fairly stable.

TYPE 2 - monitoring and control of the diet. controlled carbohydrate intake. Substituting sugars for polysaccharides as they take time to be digested and absorbed so avoids sharp spikes in blood glucose concentration

*Insulin injections


What is GM Insulin produced from?

Escherichia coli -E.Coli bacteria.

The human insulin gene is inserted into them, which the bacteria then they use the genetic code to make human insulin.


What other methods have previously been used to create insulin?

Taking insulin from slaughtered animals - usually pigs.


What are the benefits/cons to using pig insulin/GM Insulin?

Pig Insulin differs slightly from human Insulin.

Some people say with GM Insulin they are less away that their glucose levels are fluctuating than with pig Insulin.

Slaughtering pigs is immoral.

GM is easier to produce to a repeatable standard and concentration

GM is an exact copy of human insulin so is faster and more effective, there is less chance of developing a tolerance, less chance of rejection by immune response, lower rise of infection, cheaper and less morally questionable.


How can stem cells possibly provide a cure for diabetes?

Stem cells are cells that have not fully differentiated and are able to divide and form speciailised cells.

It may be possible to transplant stem cells into a pancreas with no functioning beta cells to form new beta cells that can secrete insulin.


What are the drawbacks so far of stem cell research?

Adult stem cells are limited to what they can differentiate into - they can't differentiate into Beta cells.

But cells from bastocysts can - embryonic stem cells could provide new beta cells.


What are the uses of stem cell therapy for Diabetes that involves white blood cells?

Patient's white blood cells were removed and patients were given chaemotherapy to destroy white blood cells attacking the pancreas. Stem cells were harvested.

The harvested stem cells were replaced - to make new white blood cells that do not attack the blood cells.

Control of the heart

What does it mean when they say the heart muscle is 'myogenic'?

The heart muscle naturally contracts and relaxes without needing nerve impulses.

muscle tissue can initiate its own contractions.

Control of the heart

What are contractions initiated at?

The Sino Atrial Node sends an action potential that travels as a wave through the Atrio Ventricular Node, down the Purkyne fibres to ventricles, causing them to contract

Control of the heart

What controls the pace that is set by the SAN?

the SAN recieves impulses from two different nerves- the Vagus/parasympathetic nerve and sympathetic nerve.

Control of the heart

What is

a) the vagus/parasympatheic nerve

b) the sympathetic nerve

and the function of each?

a) The nerve which slows down the rate at which the SAN fires when action potentials arrive along it

b) The nerve that speeds up heart rate.

Control of the heart

What can affect the activity of the para/sympathetic nerves?

Increase in CO2 Concentration - increases heart rate

Adrenaline - increases heart rate.

Control of the heart

What are the 5 factors that affect heart rate?

1) Stretch receptors in muscles detect movement of the limbs. Impulses are send to the cardiovascular centre, heart rate is increases as more oxygen is needed.

2) CO2 produced by muscles during exercise reduces the pH of blood plasma. This is detected by chemoreceptors which send impulses to the cardiovascular centre to increase heart rate.

3) CO2 conc in the blood falls when exercise stops, reducing the activity of the sympathetic nerve, thus decreasing heart rate.

4) Adrenaline increases the heart rate

5) If the blood pressure rises too high (perhaps during vigorous exercise), stretch receptors send signals to the cardiovascular centre to reduce heart rate.

Control of the heart

Why is it important that the heart adapts to meet the requirements of the body?

Because the requirements of cells varies depending on their activity

Control of the heart

How is the heart adapted?

can change...-heart rate-strength of contractions-increase stroke volume (volume of blood pumped per beat)