Principles - The Endocrine Glands Flashcards
(35 cards)
What is the endocrine system?
A number of anatomical structures called endocrine glands - responsible for manufacturing, storing and releasing at least one hormone
Name 2 ways in which hormone negative feedback can go wrong.
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)
What can clinical problems arise from?
Hyper secretion of a hormone or hypo secretion of a hormone
What are the main endocrine glands? (8)
Head: hypothalamus, pituitary Neck: parathyroid (4), thyroid Abdomen: Adrenal (2), pancreas Pelvis: Ovaries in females (2) Perineum: Testes in males (2)
Where is the hypothalamus located in the brain?
It is located in the diencephalon, which forms the central core of the cerebrum
Where is the pituitary gland located in the brain?
It is the midline structure in the pituitary fossa of the sphenoid bone
What connects the hypothalamus and pituitary glands?
The infundibulum or pituitary stalk
What is the pituitary gland divided into?
The anterior and posterior pituitary
What do the hypothalamus and POSTERIOR pituitary do?
- Axons of hypothalamic neurones pass down infundibulum into posterior pituitary
- These neurones produce OXYTOCIN and VASOPRESSIN (ADH)
- hormones transported to posterior pituitary for release
What do the hypothalamus and ANTERIOR pituitary do?
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
What hormones does the anterior pituitary release?
GH (growth hormone) Prolactin (milk production) TSH (thyroid stimulating hormone) ACTH (adrenocorticotrophic hormone) LH (lutenising hormone - gonads) FSH (follicle stimulating hormone - ovaries)
What is the hypophyseal portal system?
Drains venous blood:
- from hypothalamus to anterior pituitary capillary beds (this blood contains releasing hormone or release-inhibitory hormone)
- 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)
Give two examples of a portal system.
Hypophyseal portal system and hepatic portal system
What is the pituitary gland often referred to as and why?
The master gland
As the anterior lobe hormones control the output of hormones from many other endocrine glands
What are the two thyroid hormones?
Triiodothyronine (T3) and thyroxine (T4)
What is the thyroid gland closely related to?
The larynx and trachea in the anterior neck
What does the thyroid gland use to manufacture the two thyroid hormones?
iodine
Dietary lack of iodine is one cause of an enlarged thyroid gland
What is an enlarged thyroid gland called?
a goitre
Where are the 4 parathyroid glands located?
On the posterior surfaces of the thyroid gland’s lobes
What do the parathyroid glands secrete?
parathyroid hormone (PTH) This controls the amount of calcium in blood and bone - not under pituitary control
What is the blood supply of the thyroid/parathyroid gland?
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)
What is the venous drainage for the thyroid and parathyroid glands?
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
What is the blood supply of the pancreas?
Coeliac trunk and superior mesenteric artery
What is the venous drainage of the pancreas?
Splenic vein and superior mesenteric vein, then into the hepatic portal vein for cleaning in the liver (then into hepatic veins, then IVC)
