L6 The Endocrine System Flashcards

1
Q

What is the definition of a hormone?

A

Signalling molecules/mediators secreted from endocrine cells into the bloodstream

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2
Q

What are the 7 classic endocrine glands?

A
  • Pituitary (anterior and posterior)
  • Thyroid
  • Parathyroids
  • Adrenals (cortex and medulla)
  • Ovaries
  • Testes
  • Pancreas
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3
Q

Can you name 6 endocrine tissues?

A
  • Hypothalamus
  • Kidneys
  • GI tract
  • Heart
  • Liver
  • Adipose tissue
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4
Q

Name the three main chemical classes of hormones.

A
  • Peptide
  • Amino acid derived
  • Steroids
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5
Q

How do peptide hormones differ in synthesis from steroid hormones?

A

Peptide hormones are synthesized from amino acids, while steroid hormones are metabolites of cholesterol.

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6
Q

How do steroid hormones differ in which receptors it would bind to?

A

Steriod hormones would diffuse into cells and then bind to the intracellular/ nuclear receptors whereas the other two types of hormones would bind to the cell membrane on the surface receptors

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7
Q

What are the response times in the 3 different classes of hormones?

A

Peptide - Seconds to minutes
Amino acid derived - Seconds to minutes
Steriods - Hours to days

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8
Q

What is the release mechanism for steroid hormones?

A

Lipid soluble, they diffuse into cells and bind to intracellular/nuclear receptors.

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9
Q

What is a key characteristic of endocrine glands?

A

They do not have ducts.

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10
Q

Fill in the blank: Endocrine signaling enables cell signaling across _______ distances.

A

long

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11
Q

True or False: Endocrine signaling is fast.

A

False

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12
Q

What regulates the release of parathyroid hormone (PTH)?

A

Plasma calcium levels sensed by Chief cells

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13
Q

What does the parathyroid gland do?

A

They are responsible for regulating calcium levels in the blood. They produce PTH which helps maintain Ca2+ levels

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14
Q

How does the parathryoid gland lower calcium levels?

A
  • Increased calcium conc sensed by chief cells
  • PTH release ⬇️
  • Kidney tubule reabsorption ⬇️
  • Bone calcium resorption ⬇️
  • Intestinal calcium absorption ⬇️
  • Resulting in lowering plasma calcium conc
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15
Q

Describe the role of the hypothalamus in endocrine control.

A

Regulates the anterior pituitary (adenohypophysis) through releasing hormones and the posterior pituitary (neurohypophysis).

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16
Q

What hormones do the adrenal cortex release?

A
  • Glucocorticoids (e.g., cortisol)
  • Mineralocorticoids (e.g., aldosterone)
17
Q

The adrenal gland is seperated into two parts. What are they?

A

Adrenal cortex
Adrenal Medulla

18
Q

What is the primary function of insulin?

A

Decrease blood glucose levels by increasing glucose storage in muscle and decreasing glucose synthesis in the liver.

19
Q

What type of feedback loop regulates parathyroid hormone (PTH)?

A

Simple negative feedback loop

20
Q

Fill in the blank: The anterior lobe of the pituitary is also known as the _______.

A

adenohypophysis

21
Q

What is the function of the Leydig cells in the testes?

A

Produce the steroid hormone testosterone, stimulating protein synthesis and development.

22
Q

What do the adrenal medulla chromaffin cells release?

A

Catecholamines, including adrenaline and noradrenaline.

23
Q

How does the thyroid gland regulate metabolism?

A

Through T3 and T4 hormones, which bind to nuclear receptors to regulate transcription.

24
Q

What two things does the thyroid gland regulate?

A

Metabolism - basal metabolic rate
Development and growth

25
True or False: Hormones can interact with specific tissues/organs.
False ## Footnote They are specific to receptors but not specific to tissues/organs
26
What is the role of the islets of Langerhans in the pancreas?
Release insulin from β cells and glucagon from α cells into portal blood.
27
Which hormone is produced by the ovaries?
Oestrogen and Progesterone
28
What influences the synthesis and release of thyroid hormones?
Hypothalamic-pituitary hormones and iodine
29
What is the mechanism of action for peptide and amino acid-derived hormones?
Bind to cell membrane surface receptors.
30
Define endocrine gland
A ductless organ that produces hormones and releases them directly into the bloodstream
31
Define endocrine cells
A specialised tissue that produces hormones and releases them into the bloodstream
32
Where are endocrine cells generally located?
- Close proximity to capillary beds - Found in endocrine tissues or glands
33
What is the adenohypophysis?
The front lobe (anterior lobe) of the pituitary gland ## Footnote Develops from an upward projection of the pharynx
34
What is the neurohypophysis?
Also known aas the posterior pituitary, it is the back lobe of the pituitary gland ## Footnote Develops from a downward projection of the brain
35
How does the hypothalamus control the function of the anterior pituitary gland?
The adenohypophysis is controlled by the hypothalamus through the **release of hormones** (into the hypophyseal portal system). These hormones, produced by the **hypothalamic neurons**, stimulate or inhibit the activity of the **troph cells**, thereby regulating their hormone secretion
36
How does the hypothalamus control the function of the posterior lobe (neurohypophysis) of the pituitary gland?
It releases hormones from** large diameter neurons** directly into the **systemic cirulcation**
37
What two ways can hormonal release can be regulated by?
-Simple negative feedback loops e.g PTH - Hierarchical control: cortical control, inhibition of releasing hormone release, inhibition of tropic hormones release
38
Give me examples of simple negative feedback loops in hormone release
- Blood glucose regulation (insulin and glucagon) - Thyroid hormone regulation (T3 and T4) - Calcium regulation (PTH)