Session 8 Lecture 1 Flashcards
(89 cards)
What do the hypothalamus and pituitary gland form?
A complex functional unit that serves as the major link between the endocrine and nervous system
Where is the pituitary gland located?
Site beneath the hypothalamus in a socket of bone called sella turcica at the base of the skull
What do the hypothalamus and pituitary gland modulate?
Body growth, reproduction, adrenal gland function, water haemostasis, milk secretion, lactation, thyroid gland function and puberty
What does the pituitary gland consist of?
Anterior lobe and posterior lobe
What is the anterior lobe also called?
Adenohypophysis
What is the posterior lobe also called?
Neurohypophysis
What is the difference between the anterior and posterior lobe?
They have distinct embryological origins and distinct functions
What is the embryological origin of the anterior pituitary?
arises from oral ectoderm (rathke’s pouch) growing up from the roof of the mouth (primitive gut tube)
What is the emboli gal origin of the posterior pituitary?
Arises from ectodermal tissues growing downwards from the diencephalon of the developing brain (primitive brain tissue)
Is there a physical link between the hypothalamus and pituitary gland?
Yes - between the posterior lobe of pituitary and the hypothalamus
What is the infundibulum?
This is a structure through which the axons form the hypothalamus pass down and terminate in the posterior pituitary
Why is the posterior pituitary not its own gland?
Because it does not synthesise any hormones and consists of axones and terminals that originated in the hypothalamus
What is the neurocrine function of the posterior pituitary ?
Oxytocin and antidiuretic hormone (ADH) are synthesised by the hypothalamus but stored and released form the posterior pituitary.
Where is the oxytocin and ADH produced?
By neursecretory cells in the supraoptic and paraventricular nuclei of the hypothalamus
How does the oxytocin and the ADH get from the hypothalamus to the posterior pituitary?
Transported down nerve cell axons
What is the function of oxytocin?
Milk let down and uterus contractions during birth
What stimulates the release of oxytocin?
The stimulus of suckling. Also during childbirth, the stimulus of pressure on the cervix and uterine wall
What does ADH stand for?
Anti-diuretic hormone
What is another name for ADH?
Vasopressin
What is the function of ADH?
Regulation of body water volume
How is the control over the anterior pituitary gland controlled?
Mediated by tropic hormones released by the hypothalamus into the local blood supply
How do the hormones synthesised by the hypothalamus travel to the anterior pituitary?
Transported down axons an stored in median eminence
How are the hormones released from the anterior pituitary?
Released from the median eminence into the local system of blood vessels called the hypophyseal portal system
Why are the tropic hormones so named?
Because they affect the release of other hormones
