Principles - The Endocrine Glands

Question 1

What is the endocrine system?

Answer 1

A number of anatomical structures called endocrine glands - responsible for manufacturing, storing and releasing at least one hormone

Question 2

Name 2 ways in which hormone negative feedback can go wrong.

Answer 2

1 - the target cells sensitivity to the hormone may change
2 - a tumour may be: functioning (too much hormone secreted) or non functioning (tumour destroys gland and too little hormone is secreted)

Question 3

What can clinical problems arise from?

Answer 3

Hyper secretion of a hormone or hypo secretion of a hormone

Question 4

What are the main endocrine glands? (8)

Answer 4

Head: hypothalamus, pituitary
Neck: parathyroid (4), thyroid 
Abdomen: Adrenal (2), pancreas 
Pelvis: Ovaries in females (2)
Perineum: Testes in males (2)

Question 5

Where is the hypothalamus located in the brain?

Answer 5

It is located in the diencephalon, which forms the central core of the cerebrum

Question 6

Where is the pituitary gland located in the brain?

Answer 6

It is the midline structure in the pituitary fossa of the sphenoid bone

Question 7

What connects the hypothalamus and pituitary glands?

Answer 7

The infundibulum or pituitary stalk

Question 8

What is the pituitary gland divided into?

Answer 8

The anterior and posterior pituitary

Question 9

What do the hypothalamus and POSTERIOR pituitary do?

Answer 9

1. Axons of hypothalamic neurones pass down infundibulum into posterior pituitary
2. These neurones produce OXYTOCIN and VASOPRESSIN (ADH)
3. hormones transported to posterior pituitary for release

Question 10

What do the hypothalamus and ANTERIOR pituitary do?

Answer 10

Hypothalamic neurones secrete either:

• releasing hormones to stimulate pituitary to release its hormones into blood stream
• release-inhibitory hormones to prevent the anterior pituitary from releasing hormones

Anterior pituitary then releases or doesn’t release hormones

Question 11

What hormones does the anterior pituitary release?

Answer 11

GH (growth hormone)
Prolactin (milk production)
TSH (thyroid stimulating hormone)
ACTH (adrenocorticotrophic hormone)
LH (lutenising hormone - gonads)
FSH (follicle stimulating hormone - ovaries)

Question 12

What is the hypophyseal portal system?

Answer 12

Drains venous blood:

1. from hypothalamus to anterior pituitary capillary beds (this blood contains releasing hormone or release-inhibitory hormone)
2. from the anterior pituitary a second set of veins drains the venous blood to the hypophyseal veins and then eventually the SVC (this blood contains the anterior pituitary hormones)

Question 13

Give two examples of a portal system.

Answer 13

Hypophyseal portal system and hepatic portal system

Question 14

What is the pituitary gland often referred to as and why?

Answer 14

The master gland

As the anterior lobe hormones control the output of hormones from many other endocrine glands

Question 15

What are the two thyroid hormones?

Answer 15

Triiodothyronine (T3) and thyroxine (T4)

Question 16

What is the thyroid gland closely related to?

Answer 16

The larynx and trachea in the anterior neck

Question 17

What does the thyroid gland use to manufacture the two thyroid hormones?

Answer 17

iodine

Dietary lack of iodine is one cause of an enlarged thyroid gland

Question 18

What is an enlarged thyroid gland called?

Answer 18

a goitre

Question 19

Where are the 4 parathyroid glands located?

Answer 19

On the posterior surfaces of the thyroid gland’s lobes

Question 20

What do the parathyroid glands secrete?

Answer 20

parathyroid hormone (PTH)
This controls the amount of calcium in blood and bone - not under pituitary control

Question 21

What is the blood supply of the thyroid/parathyroid gland?

Answer 21

Right inferior thyroid artery
Left superior thyroid artery
These come from the three branches of the arch of the aorta (blood for head, neck and upper limbs)

Question 22

What is the venous drainage for the thyroid and parathyroid glands?

Answer 22

Right superior, middle and inferior thyroid veins

These are branches of the veins draining blood fro the head neck and upper limbs - go to the SVC

Question 23

What is the blood supply of the pancreas?

Answer 23

Coeliac trunk and superior mesenteric artery

Question 24

What is the venous drainage of the pancreas?

Answer 24

Splenic vein and superior mesenteric vein, then into the hepatic portal vein for cleaning in the liver (then into hepatic veins, then IVC)

Question 25

What hormones does the endocrine pancreas (islets of Langerhan) produce?

Answer 25

insulin
glucagon
somatostatin

Question 26

Where are the adrenal glands?

Answer 26

In the retroperitoneum, capping the superior poles of the kidneys

Question 27

What does the adrenal cortex produce?

Answer 27

Glucocorticoids (under pituitary ACTH control), mineralocorticoids and androgens

Question 28

What does the adrenal medulla produce?

Answer 28

Adrenaline and noradrenaline

Question 29

What 3 arteries supply each adrenal gland?

Answer 29

right or left
inferior, middle and superior suprarenal arteries (branch of the renal artery, which is a paired branch of the abdominal aorta)

Question 30

What is the venous drainage of the adrenal glands?

Answer 30

right suprarenal vein (drains into IVC)

left suprarenal vein (drains into left renal vein, then IVC)

Question 31

Where are the testes?

Answer 31

IN the scrotum, male perineum

Question 32

What do the testes produce?

Answer 32

Testosterone in response to anterior pituitary LH

Question 33

What do ovaries produce?

Answer 33

Oestrogen and progesterone in response to FSH and LH fro anterior pituitary

Question 34

What is the blood supply to the gonads?

Answer 34

The gonadal arteries (paired branches of the abdominal aorta)

Question 35

What is the venous drainage of the gonads?

Answer 35

Right gonad directly into IVC

Left gonad into left renal vein then IVC