Exam 3: Hypothalamus

Question 1

Hypothalamus Sulcus

Answer 1

Located beneath the thalamus, separated from the thalamus by a thin membrane called the hypothalamus sulcus

Question 2

What ventricle is formed by the hypothalamus?

Answer 2

Forms the walls and floor of the inferior portion of the third ventricle

Question 3

Median Eminence

Answer 3

The median eminence is the region where the hypothalamus will release regulating factors into the anterior pituitary

Question 4

Paraventricular nucleus (PVN)

Answer 4

– descending autonomic control (output), limbic system input

Question 5

Medial Preoptic Nucleus

Answer 5

– reproductive behaviors

Question 6

Suprachiasmatic nucleus (SCN)

Answer 6

– circadian clock

Question 7

Dorsomedial nucleus

Answer 7

– descending autonomic control (output), limbic system input

Question 8

Mammillary bodies

Answer 8

– outputs to thalamus and receives inputs from limbic system, key region for limbic aspects of hypothalamus

Question 9

Ventromedial nucleus

Answer 9

appetite control

Question 10

How does the SCN respond to light?

Answer 10

a. During the day, retinal light exposure activates SCN neurons, which in turn inhibit activity of the paraventricular nucleus in the hypothalamus (PVN) via GABAergic projection.
b. At night, diminished retinal light lowers stimulation of the SCN, releasing the PVN from inhibition.

Question 11

How is melatonin administered?

Answer 11

• The PVN then activates preganglionic sympathetic neurons which, in turn, activate the postganglionic superior cervical neurons.
• Postganglionic fibers release norepinephrine on the pineal gland promoting the synthesis of melatonin
• Melatonin is secreted into the blood stream where it controls peripheral circadian clocks
• Melatonin eventually feedbacks to the SCN to stop its production.

Question 12

What is the pituitary gland?

Answer 12

Pituitary gland is an endocrine gland that secretes nine hormones to regulate homeostasis

Question 13

Anterior Pituitary Developmental Origins

Answer 13

The anterior pituitary arises from an invagination of the oral ectoderm and forms Rathke’s pouch.

Question 14

Posterior Pituitary Developmental Origins

Answer 14

The posterior pituitary develops as an extension of the hypothalamus

Question 15

Stress Response Systems

Answer 15

1) Sympathetic: Fight-or-flight (fast)
- Sympathetic nervous system is activated, increasing heart rate, respiration, and blood pressure.
2) Hypothalamic Pituitary Adrenal (HPA) axis (slower, minutes)
- Release glucocorticoids that increase energy though glucose metabolism, lipolysis, and proteolysis, while suppressing growth, reproduction, and the immune system

Question 16

Anterior Pituitary and Hormones

Answer 16

1) Is glandular in that it contains endocrine cells that produce hormones that are released into the blood stream to regulate tissues in the periphery
2) Paravocellular neurons in the PVN secrete releasing hormones via the supraoptic hypophyseal portal system to control the release of anterior pituitary hormones.
3) Adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex to produce cortisol, which is critical for the stress response

Question 17

Posterior Pituitary and Hormones

Answer 17

1) Is not glandular and does not produce its own hormones
2) Instead, vasopression and oxytocin produced in the magnocellular neurons of the PVN are released via axonal projections into the posterior pituitary. From there these hormones can be released into the bloodstream or stored for later release.