Introduction to endocrine system Flashcards

1
Q

What kind of feedback do endocrine glands show?

A

Negative feedback.

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2
Q

What are the three classes of hormones?

A

Amines/amino acids, peptides of proteins, or steroid hormones.

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3
Q

What is tyrosine?

A

An amino acid that can give rise to thyroid hormones but also adrenaline/noradrenaline.

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4
Q

What is an example of a protein hormone?

A

Insulin.

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5
Q

What is an example of a steroid hormone?

A

Sex hormones such as oestrogens, androgens, progestorones.

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6
Q

What do the pituitary, thyroid and adrenal glands all have in common?

A

They are regulated by the hypothalamus and the pituitary gland.

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7
Q

What does the medulla in the adrenal gland release?

A

Adrenaline and noradrenaline.

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8
Q

What does the adrenal cortex release?

A

Cortisol, corticosterone, cortisone, aldosterone and androgens.

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9
Q

What does the thyroid release?

A

Thyroxine, triodothyronine and calcitonin.

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10
Q

What does the hypothalamus release?

A

ADH and oxytocin.

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11
Q

What does the anterior pituitary gland release?

A

ACTH, TSH, GH, PRL, FSH, LH, MSH.

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12
Q

What does the pineal gland release?

A

Melatonin - hormone involved in regulating sleep and waking cycles and establishing the 24 hour rhythms.

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13
Q

What does the heart release?

A

Atrial natruiretic peptide.

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14
Q

What does the kidney release?

A

Renin and erythropoietin.

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15
Q

What is a major morphological feature of endocrine glands?

A

They are ductless.

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16
Q

What are features of endocrine glands?

A

They have a good supply, the secrete messengers directly into the circulation.

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17
Q

What is an example of a primary endocrine gland?

A

Pituitary glands, thyroid and adrenal.

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18
Q

What organs have secondary endocrine function?

A

The brain, heart, kidney and GI tract.

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19
Q

What is intracrine signalling?

A

Signalling within a cell (producing products that signal within the cell).

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20
Q

What is autocrine signalling?

A

Signalling where it releases something back on itself (the cell itself).

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21
Q

What is paracrine signalling?

A

Releasing things that affect neighbouring cells.

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22
Q

What is endocrine signalling?

A

When products are secreted into the bloodstream and can travel a distance to their target cells.

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23
Q

What is neuroendocrine signalling?

A

Modified nerve cells that can secrete hormones into the circulation directly and travel to distant target cells.

24
Q

What are the four main areas in which hormones are important in?

A

Reproduction, growth and development, maintenance of internal environment and regulation of energy.

25
Q

How can hormones act differently on different tissues?

A

Different tissue-specific effects, depending on the tissue.

26
Q

What are catecholamines derived from?

A

Tyrosine?

27
Q

What are some catecholamines?

A

Adrenaline and noradrenaline.

28
Q

What are thyroid hormones derived from?

A

Tyrosine.

29
Q

What are examples of thyroid hormones?

A

Thyroxine and triiodothyronine.

30
Q

How is adrenaline formed?

A

Tyrosine is converted to L-DOPA via tyrosine hydroxylate which is then converted to dopamine via dopa decarboxylase. Dopamine is then converted to noradrenaline via dopamine-beta-hydroxylase. It’s then converted into adrenaline phenylethanolamine N-methyl transferase.

31
Q

How are thyroid hormones synthesised?

A

Tyrosine and iodine combined to form mono-iodotyrosine.

32
Q

How is thyroxine formed?

A

The combination of two di-iodotyrosine molecules.

33
Q

How is triiodothyronine formed?

A

Di-iodotyrosine combines with mono-iodotyrosine.

34
Q

What does adenylyl cyclase do?

A

It converts ATP to cAMP.

35
Q

What does cAMP do?

A

It phosphorylates protein kinase to make it active which then phosphorylated

36
Q

What happens to the phosphoproteins formed from PKA?

A

They will be packed into a lipid droplet from (LDL), go to the SER and mitochrondrion and diffuse into the blood.

37
Q

What are peptides?

A

Short amino acid chains.

38
Q

What are some examples of polypeptide hormones?

A

Insulin and prolactin.

39
Q

What are some protein hormones?

A

Thyroid stimulating hormones, follicle stimulating hormone and growth hormone.

40
Q

What are some short amino acid chain hormones?

A

ADH and oxytocin.

41
Q

What is a prohormone?

A

It needs to be cleaved by digestive hormones to the final hormone product that can then be released into the bloodstream.

42
Q

Where are peptide and protein hormones stored?

A

In secretory vesicles that are capable of being released straight away on demand.

43
Q

What does the ability of a cell to respond to a hormone depend on?

A

The presence of receptors for that hormone on or in the target cell.

44
Q

How can the number of receptors for a hormone be regulated?

A

Up-regulation or down-regulation.

45
Q

What types of receptors can bind to hormones?

A

Cell surface receptors or intracellular receptors.

46
Q

What happens when a hormone binds to cell surface receptors?

A

They activate an intracellular signalling cascade.

47
Q

What happens when substances bind to intracellular receptors?

A

They activate gene transcription.

48
Q

What hormones bind to intracellular receptors?

A

Corticosteroids.

49
Q

What hormones activate cell surface receptors?

A

Insulin.

50
Q

What are the two ways in which hormones can be released in response to a stimulus?

A

The stimulus can act on endocrine cells that causes a hormone to be released directly that acts on target cells, or the stimulus can act on a hypothalmic neurone and release a regulatory hormone that acts on the target endocrine organ to release a second hormone to act on the target cells and bring about the response.

51
Q

What are features of the responses caused by hormones?

A

It is a relatively slow transfer of information, it can be long lasting and all the cells are contacted - specificity is determined by receptors.

52
Q

What pattern do hormones regulated by the hypothalamus and pituitary gland show?

A

Circadian rhythm (24 hour rhythm) - the cycle starts at midday and goes through the evening.

53
Q

What is hypo-secretion (example)?

A

When there is too little secretion of a hormone e.g. type 1 diabetes.

54
Q

What is hyper-secretion (example)?

A

Too much secretion e.g. pancreatic endocrine tumour.

55
Q

What is hypo-responsive (example)?

A

Cells are not as responsive as they should be e.g. type 2 diabetes.

56
Q

What is hyper-responsive (example)?

A

Cells are too responsive to hormones e.g. TSH receptor constitutive activation e.g. hyper thyroidism.

57
Q

Name some common endocrine problems.

A

Hyperthyroidism, type1/2 diabetes, renin-dependent hypertension.