Pancreas Flashcards Preview

A Level Biology - Unit5 > Pancreas > Flashcards

Flashcards in Pancreas Deck (26):
1

What is an exocrine gland?

produces enzymes and releases them into a duct via the duodenum

2

What is an endocrine gland?

produces hormones and releases them into the blood.

3

What is the role of the pancreas as an exocrine gland?

To produce and secrete amylases, proteases and lipase into the pancreatic duct which are then released into the duodenum.

4

What is the role of the pancreas as an endocrine gland?

Produces insulin and glucagon which are released directly into the blood stream at specific times to help regulate blood glucose levels.

5

What is the small region of endocrine tissue called found in the pancreas?

Islets of Langerhans

6

What are the two main types of cells found in the islets of langerhans and what does each secrete?

Alpha cells- produce and secrete glucagon
Beta cells- produce and secrete insulin

7

What is the shape of the islets of langerhans?

large spherical clusters.

8

What is the shape of the pancreatic acini?

small berry-like clusters

9

What is the normal concentration that blood glucose is maintained at?

90 mg cm^-3

10

How can blood glucose conc. increase as a result of diet?

By eating carbohydrate-rich foods, the carbohydrates are broken down and glucose is released into the blood stream.

11

Blood glucose concentration can increase as a result of glycogenolysis. What is this?

Glycogen stored in the liver and muscle cells is broken down into glucose.

12

What is the name for the production of glucose from non-carb sources like from adding glucose to glycerol and amino acids?

Gluconeogenesis

13

What two main ways cause a decrease in blood glucose concentration levels?

Respiration and Glycogenesis

14

What is glycogenesis?

production of glycogen by converting excess glucose in the diet.

15

How does insulin act to reduce the concentration of glucose in the blood after a sugary meal has been eaten?

Beta cells detect the rise in blood glucose conc.
They produce and secrete insulin into the bloodstream.
Insulin in the blood lowers BGC by:
1) increase rate of glucose absorption by cells
2) increase respiratory rate of cells
3) increase rate go glycogenesis in the liver
4) increase rate of glucose to fat conversion
5) inhibit release of glucagon from alpha cells

16

How does glucagon help to increase the concentration of glucose in the blood?

Alpha cells detect the decrease in blood glucose concentration.
They produce and secrete glucagon into the bloodstream.
Glucagon increases BGC by:
1) glycogenolysis- liver breaks down glycogen store into glucose and releases it.
2) reduces the amount of glucose absorbed by liver cells.
3) increases gluconeogenesis- conversion of amino acids and glycerol into glucose.

17

When does negative feedback occur in the control of blood glucose levels?

When levels fall below a set level, the B cells stop producing as much insulin.
When levels rise above a set level, the a cells stop their secretion of glucagon.

18

Insulin and glucagon are antagonistic hormones. What does this mean?

They work against each other but also together to maintain the correct level of blood glucose concentration.

19

What is the mechanism by which insulin is secreted?
(you can bullet point the process step by step)

1) At normal BGC levels, K+ channels are open on membrane of B cells. K+ ions diffuse out of the cell and the inside of the cell is at -70mV.
2) BGC rises and glucose enters the cell by a glucose transporter
3) Glucose is metabolised in mitochondria and ATP is made.
4) ATP binds to ATP-sensitive potassium channels causing them to close.
5) No K+ diffuse out so the pd reaches -30mV. Depolarisation occurs.
6) Depolarisation causes voltage-gated calcium channels to open.
7) Ca2+ enter cell and cause secretory vesicles to release insulin.

20

What are the common symptoms of diabetes?

High blood glucose conc.
Glucose in urine
Excessive need to urinate
Excessive thirst
Constant hunger
Weight loss
Blurred vision
Tiredness

21

What is the cause of Type 1 diabetes?

Unknown cause.
However, we know that the B cells in the pancreas cannot produce insulin in patients with type 1 diabetes.
Possibly because the body attacks and destroys its own B cells as an autoimmune disease.

22

What is the cause of Type 2 diabetes?

The persons B cells don't produce enough insulin or the persons body doesn't respond efficiently to the insulin being released.
Due to obesity, overeating, little to no exercise

23

How is type 1 diabetes treated?

Regularly check blood glucose levels by pricking their finger and analyzing the blood in a machine.
They inject the insulin in their body regularly.

24

How is type 2 diabetes treated?

Increasing exercise levels.
Follow a uniquely tailored diet plan
Drugs are taken that stimulate insulin production.

25

What are the advantages of producing insulin by genetically modifying bacteria?

Human insulin is produced in a pure form.(less likely to cause allergic reactions)
Insulin is made in higher quantities
Production costs are cheaper
Overcome ethical and religious issues of using animal insulin.

26

What are the advantages of using stem cells to treat diabetes?

*Donor availability won't be an issue- stem cells produce an unlimited amount of B cells.
*Reduced likelihood of rejection as embryonic stem cells are not rejected by the body.
*People don't need to inject themselves with insulin.