Endocrine System Lecture

Question 1

What is the role of hormones?

Answer 1

Hormones influence metabolic activity by secretion into the bloodstream.
Involved in: cellular metabolism, growth and development, sexual development, homeostasis.

Question 2

What is an endocrine gland?

Answer 2

A ductless structure that’s rich in blood supply, responsible for hormone secretion.

Question 3

What is an exocrine gland?

Answer 3

Secretion of hormones externally onto an epithelial surface. e.g. tongue secretes saliva and the skin secretes sebum.

Question 4

What are the 3 types of hormone?

Answer 4

Amino acid derived, steroids, protein

Question 5

Describe amino acid derived hormones

Answer 5

Modified tyrosine e.g. thyroid hormone

Question 6

Describe steroid hormones

Answer 6

Synthesised from cholesterol, so they’re lipid soluble.

Able to readily cross the plasma membrane.

Require specific transporter proteins in the blood.

Question 7

Describe protein hormones

Answer 7

They are water soluble and have a short half life.

They initiate cellular change and vary in size.

Question 8

Where do hormones act?

Answer 8

They bind to receptors that can either be on the cell membrane of a surface (extracellular) or they can be intracellular.

Question 9

What are the different types of hormone activity?

Answer 9

Episodic, Diurnal and Constant

Question 10

What is episodic hormonal activity?

Answer 10

Release of hormones is in response to physiological demand

Question 11

What is diurnal hormonal activity?

Answer 11

Predictable pattern of hormonal release over 24 hours.

Question 12

What is constant hormonal activity?

Answer 12

A fairly constant blood hormone concentration for normal physiological function.

Question 13

What are the different types of hormonal stimuli?

Answer 13

Humoral, Neuronal and Hormonal.

Question 14

What is humoral stimulus?

Answer 14

Circulating molecules in the blood

Question 15

What is a neuronal stimulus?

Answer 15

A stress response, for example, the sympathetic nervous system.

Question 16

What is a hormonal stimulus?

Answer 16

Response to hormones secreted by other glands.

Question 17

What is the hypothalamus?

Answer 17

It is responsible for controlling hormone release from the anterior lobe of the pituitary gland. It releases the growth hormone releasing hormone, and the growth hormone inhibiting hormone.

It also synthesises oxytocin/antidiuretic hormone which is stored in the posterior lobe of the pituitary gland.

Question 18

What is the pituitary gland?

Answer 18

Divided into 2; anterior and posterior.

Anterior or adenohypophysis. It releases growth hormone (GH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), FSH, LH, and prolactin.

The posterior is made of mainly neural tissue, and stores ADH and oxytocin.

Question 19

What is the thyroid gland?

Answer 19

Made of 2 lobes surrounding the trachea.
In the visceral compartment of the neck surrounded by the pretracheal fascia.
Rich blood supply and innervated PNS/SNS

Secretes thyroxine.

Question 20

What is the function of thyroxine?

Answer 20

Regulates the rate of metabolism, energy use, protein production, growth and development, and the sensitivity of cells to other hormones.

Question 21

What is hyperthyroidism?

Answer 21

Too little thyroid hormones, so less metabolism, and an increase in fatigue and weight gain.

Question 22

What is hypothyroidism?

Answer 22

Graves disease: over stimulation of thyroid hormones - leads to weight loss.

Question 23

What is the parathyroid gland?

Answer 23

Secretes parathyroid hormone - responsible for calcium homeostasis.

Osteoclasts break down bone which leads to an increase in blood calcium levels.

Inactive vitamin D is converted to active vitamin D which is used for calcium absorption.

Question 24

What is the adrenal/suprarenal gland?

Answer 24

Comprised of 2 sections, the cortex, made of glandular tissue and the medulla, made of sympathetic NS derived from the neural crest.

Medulla produces epinephrine, norepinephrine and dopamine.

The cortex produces 3 main corticosteroid hormones (steroid hormones):

The Zone Glomerulosa produces mineralocorticoids which ensures homeostasis of Na+/K+

The Zona fasciculata produces glucocorticoids, for example, cortisol, responsible for energy metabolism and glucose availability.

The Zona reticularis produces gonadocorticoids which are sex steroids.

Question 25

What is the function of the pancreas?

Answer 25

Endocrine and exocrine gland. Major role in glucose homeostasis.

‘Islets of Langerhans’ cells produce glucagon and insulin.