Hypothalamus II

Question 1

What kind of input gets to the hypothalamus?

Answer 1

olfactory
visual
visceral sensation
multimodal brainstem afferents
limbic

Question 2

How does olfactory info get to the hypothalamus?

Answer 2

mdeial forebrain bundle, stria terminals, ventral amygdalofugal path and fornix

Question 3

Where does visual info go in the hypothalamus?

Answer 3

suprachiasmatic nucleus from the retina

Question 4

How does visceral info get to the hypothalamus?

Answer 4

ascending projections from the nucleus tractus solitarius, which relays info from CNIX and CNX

Question 5

What kind of multimodal brainstem afferents go to the hypothalamus?

Answer 5

medial forebrain bundle: bidirection tract including monoamine (noradrenergic A6, A1, A2) and adrenergic (C1,C2) info; seratonergic info

Question 6

How does limbic info get to the hypothalamus?

Answer 6

bidirection connections with the amygdala, hippocampus, septum via the fornix, stria terminalis, and the ventral amygdalofugal bundle

Question 7

What are circumventricular organs?

Answer 7

regions of the brain that lack a blood brain barrier and allow blood borne signals to reach chemosensitive neurons.Also allow them to use neurohumoral/hormonal mechanisms to control peripheral function

Question 8

What is the subfornical organ?

Answer 8

a circumventricular organ around the anterior wall of the third ventricle that contains angiotensin II receptors that induce drinking

Question 9

What is the organum vasculosum of the lamina terminalis? OVLT

Answer 9

may have neuroendocrine function and may contain osmoreceptors for vasopressin release
circumventricular organ

Question 10

What is the area postrema?

Answer 10

circumventricular organ in the walls of the fourth ventricle in the medulla. It is the chemoreceptor trigger zone for vomiting.

Question 11

What is the median eminence?

Answer 11

part of the pituitary stalk. major route oc fommunication between the hypothalamic-pituitary system and target effector organs. circumventricular organ.

Question 12

What is the medial forebrain bundle?

Answer 12

group of axons running rostrocaudally through the lateral hypothalamus. conntects the hypothalamus with the brainstem and basal forebrain. important for olfactory input and monoamine input

Question 13

What is the dorsal longitudinal fasciculus?

Answer 13

output of hypothalamus to the autonomic cell groups in the brainstem and spinal cord.

Question 14

What are the connections between the hypothalamus and the anterior and posterior pituitary? What is the embryological origin?

Answer 14

posterior pituitary is a true neuronal connection derived from neural ectoderm. As such, communication is very fast. called the neurohypophysis.
anterior pituitary is a hormonal connection derived from oral ectoderm/Rathke’s pouch The anterior pituitary is also called the adenohypophysis. Message from the hypothalamus conveied by the portal plexus. These are slower responses.

Question 15

What hormones are released by the neurohypophysis?

Answer 15

(posterior pituitary)

oxytocin and vasopressin (antidiuretic hormone)

Question 16

Where are oxytocin and vassopressin synthesized?

Answer 16

magnocellular neurons of the supraoptic and paraventricular nucleus

Question 17

How do oxytocin and vasopressin get to the posterior pituitary? How do they get to the body?

Answer 17

from the supraoptic and paraventricular nuclei, they are transported in the tuberohypophyseal or (more important) supraopticohypophysial tract. these are basically axons from these nuclei. the hormones are released after an AP goes down the axon.
they get to the rest of the body via release into a capillary plexus and then transport to the general circulation by the hypophyseal veins

Question 18

What does ADH/vasopressin do?

Answer 18

binds to receptors in the collecting duct of the kidney and promotes reabsorption of water. substances that suppress ADH (like alcohol) promote diuresis. also helpful during hemorrhage as a vasoconstrictor

Question 19

What is diabetes insipidus? What are the etiologies?

Answer 19

impaired or absent ADH secretion.
excessive drinking and urination seen. This is called central diabetes insipidis.
nephrogenic diabetes insipidus is when the kidneys don’t respond to ADH

Question 20

What are 3 main functions of oxytocin? Main receptors?

Answer 20

1. milk letdown (taget cell is smooth muscle of mammary alveoli)
2. stimulation of uterine smooth muscle contraction to promote birth (oxytocin receptors on uterine smooth muscles at the end of gestation = more irritable uterus)
3. maternal and affiliative behaviors (from praire vole research. probably controled by the nucleus accumbens, at least in animals)

Question 21

What are the effects of oxytocin and social cognition in humans?

Answer 21

increased trust
increased facial recognition memory
increased gaze specificity to the eye.

Question 22

What is one potential therapeutic use for oxytocin?

Answer 22

autism treatment