Pituitary, Adrenal & Thyroid Glands

Question 1

The endocrine system is a collection of glands that produce and secrete _____________.

Answer 1

Hormones

Question 2

What are the 9 major glands of the endocrine system?

Answer 2

• Hypothalamus
• Pituitary
• Thyroid
• Parathyroid
• Adrenals
• Pineal
• Pancreas
• Ovaries
• Testes

Question 3

What are hormones?

Answer 3

Chemical messengers that travel in the bloodstream, sometimes bound to proteins to help transport them to their target cells.

Question 4

What are the 3 classes of hormones?

Answer 4

1. Steroid hormones - Lipophilic (e.g. Cortisol)
2. Peptide hormones - Hydrophilic (e.g. Oxytocin, Insulin)
3. Amino acid derived hormone- Hydrophilic (e.g. Thyroid hormone)

Question 5

Why is the pituitary gland called the “master gland”?

Answer 5

Because it secretes hormones that control the actions of other endocrine glands and tissues throughout the body.

Question 6

Where is the pituitary gland in the body?

Answer 6

It is a pea-sized oval structure that is suspended under the brain by the pituitary stalk and sits within a narrow opening of the sphenoid bone.

Question 7

Which other gland is the pituitary gland closely associated with and why?

Answer 7

It is closely associated with the hypothalamus, which releases hormones in response to environmental stimuli that control the synthesis and release of the hormone of the pituitary gland.

Question 8

How many lobes does the pituitary gland have and what are they called?

Answer 8

It has two lobes, anterior pituitary and posterior pituitary

Question 9

What does the pineal gland produce?

Answer 9

The pineal gland produces melatonin, which plays a role in sleep patterns and circadian rhythms.

Question 10

What tissue does the posterior pituitary consist of?

Answer 10

Nervous tissue

Question 11

What tissue does the anterior pituitary consist of?

Answer 11

Glandular epithelial tissue

Question 12

Which gland controls the release of peptide hormones from anterior or posterior pituitary?

Answer 12

Hypothalamus

Question 13

___________ pituitary connects by neural pathway.

Answer 13

Posterior

Question 14

___________ pituitary connects by unique vascular link.

Answer 14

Anterior

Question 15

What hormones are released by the posterior pituitary?

Answer 15

• Oxytocin hormone
• Anti-diuretic (vasopressin) hormone

Question 16

What hormones are released by the anterior pituitary?

Answer 16

• ACTH
• TRH
• GH
• Prolactin
• FSH
• LH
• MSH

Question 17

What is oxytocin and where is it produced?

Answer 17

Oxytocin is a hormone that plays an important role in the female reproductive system, particularly with childbirth and breast-feeding. It is produced by the posterior pituitary.

Question 18

What are the functions of oxytocin in women?

Answer 18

• Contraction of the uterine muscle to help expel infant during childbirth
• Promotes ejection of milk from mammary glands during breast feeding; secretion increased by suckling
• Influences social behaviour; Mating/bonding with infant/relationships
• Injection (Syntocinon) used to induce labour and prevent postpartum haemorrhage

Question 19

What is Vasopressin and where is it produced?

Answer 19

Vasopressin is used to manage anti-diuretic hormone deficiency (also called Anti-Diuretic Hormone). It is produced by the posterior pituitary.

Question 20

What are the two main functions of Vasopressin?

Answer 20

• Enhances retention of water by nephrons during urine formation (anti-diuretic)
• Contraction of arteriolar smooth muscle (vessel pressor effect)

Question 21

How does Vasopressin enhance retention of water by nephrons during urine formation?

Answer 21

• Bind to V2 receptor causing an increase in water permeability in distal tubule and collecting ducts leading to increased water reabsorption
• Primary regulator of water balance (urinary)

Question 22

How does Vasopressin cause contraction of arteriolar smooth muscle (vessel pressor effect)?

Answer 22

• Binds to V1 receptor causing an increase in vasoconstriction
• Plays a minor role in regulating blood pressure

Question 23

What causes Diabetes Insipidus?

Answer 23

It is caused by a lack of vasopressin (ADH)

Question 24

What are the main symptoms of Diabetes Insipidus?

Answer 24

• Polyuria (excessive dilute urine >2L/day)
• Polydipsia

Question 25

What does polyuria mean?

Answer 25

The passage of large volumes of urine with an increase in urinary frequency.

Question 26

What does polydipsia mean?

Answer 26

Medical definition of excess thirst.

Question 27

What happens if diabetes insipidus is left untreated?

Answer 27

It leads to shock-like symptoms- Hypotension, tachycardia, tachypnea etc. and can lead to hypernatremia.

Question 28

What are the treatment options for diabetes insipidus?

Answer 28

• Vasopressin injection
• Desmopressin injection/tablet/nasal spray (no longer acting and has no effect on V2 receptors so no vasoconstriction)

Question 29

The five cell types in the anterior pituitary secrete 6 major hormones. What are they?

Answer 29

1. Somatotropes- GH (Growth hormone (somatotropin))
2. Thyrotropes- TSH (Thyroid stimulating hormone)
3. Corticotropes- ACTH (Adrenocorticotrophic hormone)
4. Gonadotropes- FSH (follicle stimulating hormone) and LH (luteinising hormone)
5. Lactotropes- PRL (prolactin)