Endocrinology

Question 1

Endocrine system

Answer 1

hormones are chemical signalling molecules that travel through the blood and reach every part of the body but only target cells have receptors that allow them to respond

Question 2

Homeostasis

Answer 2

• organisms use homeostasis to maintain a steady state or internal balance regardless of external environment

Question 3

What is the role of homeostasis mechanisms in the internal environment?

Answer 3

They moderate changes in the internal environment.

Question 4

What happens when a variable fluctuates above or below the set point?

Answer 4

It serves as a stimulus.

Question 5

What detects a stimulus in homeostasis?

Answer 5

A sensor.

Question 6

What is triggered after a sensor detects a stimulus?

Answer 6

A response.

Question 7

What does the response do in the homeostasis process?

Answer 7

It returns the variable to the set point.

Question 8

Hormone

Answer 8

A chemical messenger produced and secreted by a specialised endocrine gland that is transported in the bloodstream to a distant target organ/ cell where it elicits a physiological response

Question 10

What are the three different classes of hormones?

Answer 10

Proteins/Peptides, Cholesterol Derivatives, Modified Amino Acids

Question 11

Give an example of a hormone from the Proteins/Peptides class.

Answer 11

Growth hormone

Question 12

Are protein/peptide hormones hydrophilic or hydrophobic?

Answer 12

Hydrophilic

Question 13

What are the two examples of Cholesterol Derivatives?

Answer 13

Steroids and Vitamin D

Question 14

Are cholesterol derivative hormones hydrophilic or hydrophobic?

Answer 14

Hydrophobic

Question 15

Name two hormones that fall under Modified Amino Acids.

Answer 15

Adrenaline and Thyroid hormones

Question 16

Is adrenaline hydrophilic or hydrophobic?

Answer 16

Hydrophilic

Question 17

Are thyroid hormones hydrophilic or hydrophobic?

Answer 17

Hydrophobic

Question 18

Can non lipid-soluble hormones (e.g., protein hormones) diffuse through the phospholipid bilayer?

Answer 18

No, they cannot diffuse through the phospholipid bilayer.

Question 19

How do non lipid-soluble hormones affect their target cells?

Answer 19

They act indirectly via extracellular receptors.

Question 20

What happens when a non lipid-soluble hormone binds to an extracellular receptor?

Answer 20

It triggers an intracellular signaling cascade.

Question 21

What is the name of the intracellular signaling pathway triggered by non lipid-soluble hormones?

Answer 21

The “second messenger system.”

Question 22

stages of the second messenger model

Answer 22

• the hormone itself is the first messenger
• it binds to specific receptors on the cell-surface membrane of target cells
• forms a hormone-receptor complex
• activates an enzyme within the cell
• production of a chemical that acts as a second messenger

Question 23

Can lipid-soluble hormones diffuse through the phospholipid bilayer?

Answer 23

Yes, lipid-soluble hormones (e.g., steroid hormones) can diffuse through the phospholipid bilayer.

Question 24

Where do lipid-soluble hormones bind once inside the cell?

Answer 24

They bind to intracellular receptors.

Question 25

What is the effect of lipid-soluble hormone binding on the target cell?

Answer 25

It directly activates target molecules, usually by changing gene expression.

Question 26

hormone actions

Answer 26

- affect growth, development, metabolic activity and function of tissues - may be stimulatory or inhibitory - may act on several tissues or just one specific target tissue-major difference between endocrine and nervous system - responsive tissues must have specific receptors for that hormone

Question 27

circulating hormone levels influenced by:

Answer 27

- rate of secretion - by endocrine gland - rate of metabolism - by target tissue, blood, liver, kidney - serum binding proteins - transport in blood

Question 28

Regulation of hormone secretion - by physiological changes

Answer 28

- blood glucose regulates insulin and glucagon releases from pancreas - stress regulates adrenaline release from adrenal medulla

Question 29

Regulation of hormone secretion - by endogenous rhythms

Answer 29

- ultradian - cycles in minutes eg GnRH pulses (90 - 120 min) - Circadian - daily cycles eg testosterone (24hr) - infradian cycles - monthly eg LH in females (28 day menstrual cycle)

Question 30

Regulation of Hormone Secretion - by feedback mechanisms

Answer 30

- mostly negative - maintains homeostasis - some positive feedback - less common

Question 31

main types of endocrine dysfunction

Answer 31

- hypersecretion - hyposecretion - ectopic hormone secretion - hormone made outside normal endocrine gland (eg tumour)

Question 32

Hyposecretion: genetic

Answer 32

Caused by inherited genetic mutations that affect the production of hormones or glandular function.

Question 33

Hyposecretion: Dietary

Answer 33

Caused by inadequate intake of nutrients, especially vitamins and minerals, which are necessary for hormone production.

Question 34

Hyposecretion: Immunological (auto-immune disease)

Answer 34

Caused by the immune system attacking the body’s own tissues, including endocrine glands, leading to decreased hormone production.

Question 35

Hyposecretion: Cancer

Answer 35

Caused by tumours that damage or replace hormone-producing tissues or glands, impairing their ability to secrete hormones.

Question 36

Hyposecretion: Iatrogenic (= doctor-caused)

Answer 36

Caused by medical treatments, such as surgery, radiation, or medication, that inadvertently damage hormone-producing glands.

Question 37

Hyposecretion: Idiopathic

Answer 37

The cause is unknown or cannot be determined despite medical investigation.

Question 38

hyposecretion- treatment

Answer 38

- Hormone Replacement with Steroids: This treatment is straightforward. Steroids are absorbed in the gastrointestinal tract and have a high success rate. - Protein Hormones: The treatment with protein hormones is more difficult. These hormones must be injected and are species-specific, meaning that the treatment varies depending on the species.

Question 39

hypersecretion - functional tumour

Answer 39

a functional tumour is one that produces hormones, leading to an overproduction of hormones in the body

Question 40

hypersecretion: Ectopic Hormone-Secreting Tumour:

Answer 40

This type of tumour occurs when a tumour outside of the endocrine glands secretes hormones, causing hypersecretion.

Question 41

hypersecretion: Immunological

Answer 41

In some cases, an immunological issue can cause hypersecretion, where the immune system triggers an overproduction of hormones.

Question 42

hypersecretion: substance abuse

Answer 42

The use of certain substances, such as drugs or alcohol, can interfere with hormone regulation and lead to hypersecretion.

Question 43

Hypersecretion: treatment

Answer 43

- Surgical removal of the gland that is hyper-secreting (but will then need replacement therapy!) - Irradiation of Gland – reduce function (but will then need replacement therapy!) - Drugs that block the actions of the hormone

Question 44

Hypothalamic-pituitary system

Answer 44

- plays a major tole in coordinating the entire endocrine system - pituitary gland = conductor of the endocrine orchestra - a major interface between brain (nervous system and periphery - organizes appropriate hormonal responses to stimuli from higher centres of brain in response to changes in the external environment and changes in internal environment