Anatomy of the Hypothalamus and Pituitary Gland

Question 1

Where is the thalamus located?

Answer 1

Anterior and inferior to the thalamus, one each side of the third ventricle just above the optic chiasm

Question 2

What makes up the posterior border of the hypothalamus?

Answer 2

Mammilary bodies of the pituitary gland

Question 3

Outline the structure of the pituitary gland

Answer 3

Sits in the pituitary fossa in the sphenoid bone, underneath the optic chiasm.

Question 4

Describe the development of the anterior lobe of the pituitary gland

Answer 4

Develops form the ectoderm in the roof of the mouth and thereafter the pouch of tissue migrates upwards and separates from the oral cavity

Question 5

Describe the development of the posterior lobe of the pituitary gland

Answer 5

Develops from a downward pouch of brain tissue in the floor of the third ventricle, and the upper part of the pouch remains connected to the hypothalamus and forms the pituitary stalk.

Question 6

What is the infundibulum?

Answer 6

Pituitary stalk

Question 7

What is the median eminence?

Answer 7

Region where the pituitary stalk joins the hypothalamus

Question 8

What lies either side of the pituitary gland?

Answer 8

Cavernous sinus

Question 9

What is the functional difference between the anterior and posterior pituitary lobes?

Answer 9

Anterior pituitary is an endocrine gland whereas the posterior pituitary lobe is part of the brain

Question 10

What is the role of the hypothalamus in autonomic responses?

Answer 10

Known as the control centre of the ANS; I times of threat, information from eyes and ears is sent to the hypothalamus where the structure then sends commands to the brainstem and stimulates the sympathetic nervous system to respond

Question 11

What does the hypothalamus provide an important link between?

Answer 11

Senses and activation of the autonomic nervous system

Question 12

Outline some of the feedback-regulated control systems that the hypothalamus is involved in

Answer 12

Temperature (thermostat), body water (hydrostat), body weight (ponderostat) and role in reproduction

Question 13

Describe the hypothalamic autonomic projections

Answer 13

Lateral hypothalamus projects to the lateral medulla to drive ANS cells here including the parasympathetic vagal nuclei and cells which descend to the sympathetic NS in the spinal cord

Question 14

Describe the hypothalamic endocrine projections

Answer 14

Magnocellular neurones send axons directly to posterior pituitary and secrete oxytocin and ADH directly into the bloodstream whereas parvocellular neurones secrete peptides which regulate the release of anterior pituitary hormones

Question 15

Describe the hypophyseal portal system (anterior pituitary)

Answer 15

Axons from hypothalamus end on capillaries in the neck of the pituitary gland and release transmitter peptides into the sinusoids, these are then taken up by capillaries and travel down the portal vein to the anterior lobe to a second capillary plexus and stimulate the release of anterior pituitary hormones

Question 16

What does the release of hormones from the anterior pituitary gland involve?

Answer 16

Hypothalamic releasing hormones and hormones release from anterior pituitary cells (in response to a specific releasing hormone released by hypothalamic axons)

Question 17

What specific releasing hormone stimulates TSH release from the anterior pituitary?

Answer 17

Thyrotropin releasing hormone (TRH)

Question 18

What specific releasing hormone stimulates FSH and LH release from the anterior pituitary?

Answer 18

GnRH

Question 19

Describe the hypothalamo-hypophyseal tract (posterior pituitary)

Answer 19

Axons from paraventricular and supraoptic nuclei of hypothalamus send axons to posterior pituitary and end as secretory terminals. These terminals secrete ADH and oxytocin onto the capillaries and into venous blood

Question 20

Describe the hypothalamo-pituitary-adrenal axis

Answer 20

Activated by stress –> activates hypothalamus –> CRH release –> activates anterior pituitary –> ACTH release –> adrenal cortex activated –> cortisol release

Question 21

What is the function of cortisol?

Answer 21

Increases blood sugar, suppresses immune system, aids metabolism and allows a person to cope with physical stress e.g. exercise, hunger, cold and injury

Question 22

What is another name for the anterior lobe of the pituitary gland?

Answer 22

Adenohypophysis

Question 23

What is another name for the posterior lobe of the pituitary gland?

Answer 23

Neurohypophysis