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Bio > 5.4 > Flashcards

5.4 Flashcards

1
Q

What is the Endocrine System?

A

A system of communication which uses hormones as a signalling molecules.

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2
Q

What are hormones?

A

A steroid or protein molecule produced by glands; they target organs and tissue.

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3
Q

What is a target?

A

For a non steroid hormone a target organ or tissue will have a cell surface receptor which is complimentary to the shape of the hormone.

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4
Q

What are the two type of hormones?

A
  • Hormones from proteins and peptides; derivatives of amino acid (glucagon, insulin, adrenaline)
  • Steroid hormones (testosterone and oestrogen)
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5
Q

How do protein hormones interact with cell?

A

Bind to complimentary cell surface receptor, activating a second messenger in the cell causing changes to the activity of the cell.

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6
Q

How do steroid hormones interact with cells?

A

They diffuse through phospholipid bi layer, entering the nucleus and directly acting on the DNA.

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7
Q

Describe endocrine glands.

A

They are ductless glands which have capillaries running through them allowing secreted hormones to directly enter the blood.

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8
Q

Describe an exocrine glands.

A

They are a group of cells surrounding a duct. The hormones will be excreted into the duct and the duct will transport the hormones to required site.

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9
Q

Explain in detail how does a non-steroid hormone effect a cell?

A

1) The non-steroid hormone binds to a complimentary cell surface receptor.
2) A G-protein activates an effector molecule by converts an inactive molecule into an active molecule.
3) This effector molecule is adenyl cyclase which converts AMP to cAMP.
4) cAMP is the second messenger which causes a cascade of enzyme controlled reactions effecting cell activity.

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10
Q

What is the adrenal cortex?

A

The outer layer of the adrenal glands.

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11
Q

What is the adrenal medulla?

A

The inner layer of the adrenal glands?

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12
Q

What is Adrenaline?

A

It is a steroid hormone produced by the adrenal glands which prepare the body for a fight or flight situation.

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13
Q

What are the adrenal glands?

A

Glands situated above the kidneys which release adrenaline and enzymes such as corticoids like aldosterone.

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14
Q

What is the Zona Glomerulosa?

A

It is the outer most layer of the adrenal glands which release mineralocorticoids.

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15
Q

What is the Zona Reticularis?

A

It is the inner most layer which releases sex hormones such as testosterone and oestrogen.

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16
Q

What is the Zona Fasciulata?

A

It is the middle layer which releases glucocorticoids such as cortisol.

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17
Q

What molecule does the adrenal cortex use to produce hormones?

A

Cholesterol.

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18
Q

What is the action of a steroid hormone in the body?

A

1) It diffuses across the phospholipid bi layer.
2) It binds to a complimentary receptor in the cytoplasm
3) This receptor-steroid complex diffuses into the nucleus and binds to a receptor in the chromosomal material
4) This causes the production of mRNA used in protein synthesis.

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19
Q

What does mineralocorticoids do?

A

They regulate concentrations of potassium and sodium ions in the blood.

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20
Q

What does aldosterone do and what type of corticoid is it?

A

Aldosterone effects the cells of the distal tubule and collecting ducts.

It increases absorption of sodium ions and decreases absorption of potassium ions.

It also increases water retention therefore keeping blood pressure high.

21
Q

What do glucocorticoids do?

A

They regulate the metabolism of proteins, fats and carbohydrates in the liver.

22
Q

What does cortisol do and what type of corticoid is it?

A

Cortisol is released by the zona fasciculata in response to stress and low blood glucose concentration. It produces glucose through metabolism of glycogen.

Cortisol can also be released by the zona reticularis.

23
Q

What does the zona reticularis produce?

A

It can produce cortisol however when needed enzymes are not present it instead produces precursor molecules called androgens.

These molecules are used by the testes and ovaries to produce sex hormones which aid development of secondary sexual characteristics and gamete formation.

24
Q

What amino acid is adrenaline derived from?

A

Tyrosine.

25
Q

What affect does adrenaline have on the body:?

A

1) Stroke volume increases.
2) Smooth muscle of bronchiole relax
3) Heart beat increases
4) Pupils dilate
5) Vasoconstriction causing higher blood pressure
6) Glycogen to glucose (glycogenolysis)
7) Increased mental awareness
8) Body hairs erect
9) Decreased activity of gut

26
Q

What are beta cells?

A

Cells found in islets of Langerhans which product insulin.

27
Q

What is glucagon?

A

A hormone which increases blood glucose concentration.

28
Q

What is insulin?

A

Release from beta cells to decrease blood glucose concentration.

29
Q

What are the two main functions of the pancreas?

A
  • Releases pancreatic juices

- Releases hormones

30
Q

Describe the exocrine gland of the pancreas.

A

A group of cells in a lobule called acini with a tubule at the centre where the cells secrete fluid into.

These tubules connect to form intralobular ducts which then form the pancreatic duct leading to duodenum.

31
Q

What is in the fluid secreted by the acini.

A
  • Pancreatic amylase which is a carbohydrase that converts amylose into lactose
  • Trypsinogen which is an inactive protease becoming trypsin in active form.
  • Lipase which breaks down lipid molecules
  • Sodium hydrogen-carbonate which is alkaline that neutralises contents of digestive system due to acidic environment of stomach.
32
Q

Where are the endocrine glands of the pancreas?

A

Islets of Langerhans.

33
Q

What do alpha and beta cells produce?

A

Alpha cells produce Glucagon.

Beta cells produce Insulin.

34
Q

How is insulin released?

A

1) Beta cells have sodium and potassium ion channels with sodium ion being closed and potassium ion being open and potassium ions diffusing out. The resting cell P.D is -70mv.
2) Glucose from blood diffuses into the beta cell
3) Glucose metabolised via gluco kinase enzyme to from ATP.
4) ATP build up causes potassium ion channel to close.
5) Build up of potassium ion channels cause the sodium ions channels to open as P.D increases.
6) Sodium ions diffuse into beta cell causing vesicles of insulin to fuse with membrane and be releases via exocytosis.

35
Q

What is normal blood glucose level?

A

4-6 mmol dm cubed.

36
Q

What do you call high and low blood glucose levels?

A

Hyperglycaemia for high.

Hypoglycaemia for low.

37
Q

What happens when insulin is released and its effect on the cell?

A

It binds to cell surface receptor causing tyrosine kinase to phosphorylate inactive enzymes into active enzymes causing a cascade of enzyme controlled reactions.

1) Vesicles of cell surface transporter proteins bind to membrane.
2) More glucose diffuses into cell.
3) Glucose converted into glycogen (glycogenesis).
4) Glucose converted to fate.
5) More glucose used in respiration.

38
Q

Which cells do glucagon act on?

A

Hepatocytes (liver cells)

39
Q

What happens when glucagon is released?

A

1) Binds to complimentary cell surface receptor on the liver cells.
2) This causes a G-protein to activate the effector molecule adenyl cyclase which converts AMP to cAMP.
3) cAMP causes a cascade of enzyme controlled reactions in the cell

These effects include:
- Glycogen turning into glucose (glycogenolysis).

  • Fatty acids and amino acids into glucose (gluconeogenesis).
  • More fatty acids are used in respiration.
40
Q

What is diabetes mellitus?

A

A condition which causes the body not to be able to control blood glucose concentrations properly.

41
Q

What are stem cells?

A

Unspecialised cells with the ability to turn into any developed cell.

42
Q

What causes Type 1 diabetes (insulin-dependent)?

A

Autoimmune response where the the body starts to attack the bodies beta cells. Condition starts in childhood.

43
Q

What causes Type 2 diabetes?

A

Body can produce insulin but the body is not responsive to it. Cell surface receptors become less responsive.

44
Q

What can cause Type 2 diabetes?

A
  • Old age
  • Lack of exercise
  • Asian or Afro-Carribean origin (genes)
  • Diet with many sugars, especially refined
  • Family history
45
Q

Why is it important to treat diabetes as soon as possible?

A

Effects can become worser over time.

46
Q

How to treat type 1 diabetes?

A

Injection of insulin with specified dose and time of injection.

Insulin pump therapy- needle implanted in skin which pumps insulin periodically.

Islet cell transplant - replace beta cells with healthy ones from a deceased patient

Complete pancreas transplant.

Stem cells from bone marrow or placenta giving freedom from insulin pumps.

47
Q

How to treat type 2 diabetes?

A

Lifestyle changes:

  • Lose weight
  • Regular exercise
  • Monitor diet
  • Medication which can boost insulin production and decrease glucose released from liver.
48
Q

How is insulin for medicinal use produced?

A

Extracted from pancreas of animals such as Pigs.

Escherichia coli bacteria genetically modified to produce human insulin.

49
Q

What are the advantages of using insulin from genetically modified bacteria?

A
  • Exact copy of human insulin therefore faster and more effective
  • Less chance of developing tolerance
  • Less chance of rejection by immune response
  • Lower risk of infection
  • Cheaper to manufacture in comparison to extraction
  • More adaptable to demand
  • Less moral objections

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