Overview of the Endocrine System-18

Question 1

What are examples of hormones in adipose tissues and GI tract?

Answer 1

GI- Gastrin, Gherkin and Glucagon
Adipose- Leptin

Question 2

What is the difference between the connection in the endocrine and nervous system.

Answer 2

Endocrine system is wireless (travels in blood) and nervous system is wired (through wire like neurones)

Question 3

What is the difference between the distance travelled in the endocrine and nervous system.

Answer 3

Hormones travel long distances in the bloodstream in the endocrine system whereas neurotransmitter diffuses a short distance in the nervous system.

Question 4

What are the responding cells in the nervous system and endocrine system?

Answer 4

Endocrine- Communication depends on expression of specific receptors whereas in nervous system communication depends on anatomical relationship of neurons.

Question 5

What is the difference between the speed and duration of the endocrine and nervous systems.

Answer 5

Endocrine can be quite rapid but can also be slow and longer lasting whereas nervous system is rapid and brief.

Question 6

What processes do hormones regulate.

Answer 6

Homeostasis
Energy Metabolism
Growth and Development
Reproduction
Behaviour

Question 7

What are the three different classes of hormones

Answer 7

Peptide- Composed of a chain of amino acids
Steroid- Derived from cholesterol
Amine- Amino acid derivatives

Question 8

Where are different hormones synthesised and stored.

Answer 8

Peptide- Made in advance, stored in secretory vesicles.
Steroid hormones- Synthesized on demand from precursors
Amine hormones- Made in advance- stored in secretory vesicles

Question 9

How are different hormones released from parent cells

Answer 9

Peptide- Exocytosis
Steroid- Simple diffusion
Amine- Exocytosis and transport proteins.

Question 10

What are the half-lives of different hormones?

Answer 10

Peptide- Short
Steroid- Long
Catecholamines- short
Thyroid- Long

Question 11

Where are receptors located for different hormones

Answer 11

Peptide- Cell membrane
Steroid- Cytoplasm or nucleus
Catecholamines- Cell membrane
Thyroid- Nucleus

Question 12

What is the response to receptors of different hormones?

Answer 12

Peptide- Activators of secondary messengers and intracellular pathways.
Steroid- Activation of genes for transcription.
Catecholamines- Secondary messenger systems.
Thyroid- Activation of genes for transcription.

Question 13

What is the general target response of the different hormones.

Answer 13

Peptide- Modification of existing proteins.
Steroid- Induction of new protein synthesis
Catecholamines- Modification of existing proteins.
Thyroid- Induction of new protein synthesis.

Question 14

What are examples of each of the hormones.

Answer 14

Peptide- Insulin, parathyroid
Steroid- Estrogen, androgens, cortisol
Catecholamines- Adrenaline, Noradrenaline
Thyroid- Thyroxine(T4)

Question 15

How do the different proteins travel in blood

Answer 15

Peptide- Dissolved in plasma
Steroid- bound to carrier proteins
Catecholamines- Dissolved in plasma
Thyroid- Bound to carrier proteins.

Question 16

What factors control secretion of hormones

Answer 16

The concentration of ions or nutrients in plasma
Environmental changes
Neuronal activity
Other ‘releasing hormones, which are released from the hypothalamus and pituitary gland.

Question 17

How does the hypothalamus regulate hormone release from the pituitary gland.

Answer 17

The hypothalamus receives signals from essentially all areas of the central nervous system

The hypothalamus produces ‘releasing’ and ‘inhibiting’ hormones, which act on the pituitary gland

The hypothalamus is thus a key link between the nervous system and the endocrine system

Question 18

What is the function of the posterior pituitary?

Answer 18

Axons from the hypothalamic neurons enter the posterior pituitary

Hormones oxytocin and ADH are released from axon terminals, enter capillaries in the posterior pituitary and then released into general circulation.

Thus posterior pituitary releases hormones but does not synthesise them they are synthesised in the hypothalamus.

Question 19

Function of the anterior pituitary.

Answer 19

Hormones released from hypothalamus move through portal veins into the anterior pituitary.

These hypothalamic hormones either stimulate or inhibit hormone release from cells in the anterior pituitary.

Hormones are released from anterior pituitary into general circulation.

Some anterior pituitary hormones control the secretion of hormones from other endocrine glands.

THUS HORMONES RELEASED FROM THE ANTERIOR PITUITARY ARE SYNTHESIZED IN THE ANTERIOR PITUITARY.

Question 20

What is an example of a three hormone sequence.

Answer 20

Facilitates signal amplification from a small number of neurons in the hypothalamus to a large peripheral hormone signal.

Question 21

What are examples of feedback regulation of hormone release.

Answer 21

• The biological response to a hormone can directly feedback to the gland that secretes that hormone. (Parathyroid hormone)
• The hormone itself can exert feedback regulation (thyroid hormones)