The Endocrine System Flashcards Preview

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Flashcards in The Endocrine System Deck (29)
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1
Q

Describe endocrine hormones?

A

Secreted by endocrine glands into the blood stream where they affect other organs

2
Q

Describe paracrine hormones?

A

Secreted and acts on neighbouring cell via diffusion (i.e. neurotransmitters)

3
Q

Descibe autocrine signalling?

A

The cell secretes something that it has receptors for so it will act on itself

4
Q

How can the hormone be secreted into the blood but not affect everything?

A

Must it must bind with specific receptors on the cell surface or inside the cell in order to have its effect

5
Q

Can one endocrine gland only secrete one type of hormone? Give an example

A

No as for example the pancreas secretes insulin and glucagon

6
Q

How many different hormones can a single cell secrete - what is the exception?

A

One cell secretes one hormone except for nerve cells

7
Q

Can one type of hormone only be secreted by one endocrine gland? Give an example

A

No for example somatostatin is secreted by the pancreas and the hypothalamus

8
Q

How are peptide hormones synthesised?

A

From amino acids in cells

9
Q

How are steroid hormones synthesised?

A

From precursors in the cell

10
Q

What are the two factors that affect the concentration of hormones in the blood?

A
  1. Rate of Secretion

2. Rate of Inactivation/Excretion

11
Q

How are hormones usually removed from the blood?

A

By the kidneys and the liver

12
Q

What does the rate of removal depend on?

A

Whether they are long or short acting

13
Q

How are peptide hormones bound to receptors normally inactivated?

A

By endocytosis where the cell turns the hormone inward to be metabolised

14
Q

What are steroid and thyroid hormones bound to?

A

Proteins (the plasma)

15
Q

Why do steroid and thyroid hormones have a longer circulation time?

A

Because of their protein binding proteins means they are released slowly

16
Q

Where are receptors for peptide and catecholamine hormones?

A

On the cell surface (GPCRs)

17
Q

Where are the receptors for steroid and thyroid hormones?

A

In the cell (nuclear receptors)

18
Q

What is down regulation?

A

When a high concentration of the hormone is around for a long time and the total number of receptors for that hormone decreases

19
Q

What is an example of downregulation?

A

High levels of insulin being around leads to down regulation of receptors for it which leads to type 2 diabetes

20
Q

What is upregulation?

A

Occurs when cells are left for a long period of time without the hormone or low concentrations of it so more receptors are snthesised

21
Q

What is long loop feedback?

A

Where hormones have negative feedback on the anterior pituitary (directly) and the hypothalamus (indirectly) to inhibit their production

22
Q

What is short loop feedback?

A

The anterior pituitary hormones negatively feedback to the hypothalamus

23
Q

What is ultrashort loop feefback?

A

Where the hypothalamic hormones feedback on themselves by attaching to hypothalamic receptors to inhibit their release

24
Q

When would short loop feedback be seen?

A

Only in cases where the target organ isnt there anymore

25
Q

What is an example of long loop feedback not working?

A

Large concentration of gonadotrophins in post menopausal woman with no feedback

26
Q

Give an example of thyroid hormones participating in long loop feedback?

A

The thyroid hormones (T3, T4) act directly on the anterior pituatary and indirectly on the hyporthalamus to inhibit their production

27
Q

Give an of example of TSH in short loop feedback?

A

The thyroid stimulating hormone (thyrotrophin) is released from the anterior pituitary and acts on the hypothalamus to inhibit its release

28
Q

Give an example of TRH in ultra short loop feedback?

A

The hypothalamus releases thryotrophin release hormone which acts on the receptors on the hypothalamus to inibit its release

29
Q

What is an example of positive feedback?

A

Oestrogen acting on the anterior pituitary and the