Hypothalamus

Question 1

functions of hypothalamus?

Answer 1

1. internal homeostasis
2. endocrine control through pituitary
3. autonomic nervous system control
4. regulation of food and water intake
5. emotion and behavior
6. circadian rhythms

Question 2

function of nucleus: PVN, AH, medial preoptic, SON, SCN, VMH and mammillary body

Answer 2

paraventricular nucleus: water balance; stress; social bonding; secretes ADH (AVP) + oxytocin

medial preoptic: blood pressure; male sex; maternal care

anterior hypothalamic area (AH): body temperature; aggression

supra-optic nucleus: water balance; secretes oxytocin + ADH

suprechiasmatic: biological clock

ventromedial nucleus: satiety; female sex

mammillary body: feeding

Question 3

functional zones of hypothalamus

Answer 3

1. Periventricular-Borders the third ventricle. Important for regulation of anterior pituitary function
2. Middle Zone
   produces oxytocin and vasopressin.
   Regulates release of peptides from posterior pituitary
   Modulate autonomic nervous system.
3. Lateral Zone
   Integrates information from other limbic structures. Involved in regulation emotion and behavior.

Question 4

functional anatomy of medial preoptic area

Answer 4

Medial preoptic area- lateral zone
Regulates Reproductive Endocrinology；
Regulates Sexual and Maternal Behaviors；
Sexually Dimorphic Areas；

Question 5

functional anatomy of paraventricular nucleus (PVN)

Answer 5

1. Parvocellular neurons project to the capillaries of the median eminence (external zone) where they release vasopressin and CRF into the portal vein.
2. Autonomic division projects to the brain stem and spinal cord via the medial forebrain bundle to regulate preganglionic autonomic neurons.

Question 6

functional anatomy of SCN, VMN, and Arcuate

Answer 6

1. Suprachiasmatic nucleus- 
Circadian Rhythms.
2. Ventromedial nucleus (VMN or VMH)-
Feeding
Sexual Behavior.
3. Arcuate nucleus (periventricular)
neurosecretory cells regulating anterior pituitary hormone secretion;
Project to median eminence and terminate on portal capillary bed.

Question 7

the study shows that SCN regulates circadian period

Answer 7

Hamster Experiment
Even without light, normal hamster maintains 24 hour cycle while Tau mutant 20 hours cycle

mutation of Tau: 20 hours cycle instead of 24;
lesion of SCN makes running cycle random;
brain transplant of Tau into WT makes it run after 20 hours cycle, while transplant of WT into Tau makes it run 24 hours cycle

Question 8

anterior and posterior pituitary

Answer 8

Anterior=adenohypophysis
- Non-neuronal ectoderm
- Epithelial Cells (no neurons)
- Derived from Rathke’s Pouch (back part of mouth)/ closed system
Posterior=neurohypophysis
- Neuronal ectoderm
- neurons
- open system

Question 9

function of posterior pituitary and function of oxytocin/vasopression

Answer 9

neurons from PVN and SON project directly to the posterior pituitary and secrete oxytocin and vasopressin into the blood stream

Note: oxytocin regulates uterine contraction and milk ejection;
vasopression regulates vascular tone and water re-absorption in the kidney

Question 10

regulation of oxytocin secretion during birth

Answer 10

positive feedback: uterine contraction/cervical stimulation etc > NTS > oxytocin neurons > induce contraction

1. hypothalamus bursts
2. oxytocin released to bloodstream
3. oxytocin causes uterine contraction
4. uterine contraction causes the release of more oxytocin

Question 11

regulation of vasopressin secretion

Answer 11

1. baroreceptors: sensing blood pressure > send signal to pituitary through nucleus of the solitary tract
2. osmolarity

Question 12

functional anatomy of paraventricular and supraoptic nuclei

Answer 12

1. Magnocellular (middle zone) neurons project directly to posterior pituitary and regulate oxytocin and vasopressin release.
2. Parvocellular
3. Autonomic division

Question 13

AVP regulates water reabsorption in the kidney

Answer 13

NaCl increases AVP while alcohol decreases it

AVP opens aquaporins

Question 14

anterior pituitary (periventricular zone)

Answer 14

neurosecretory cells (most in hypothalamus) release hormones in portal vein and secondary plexus and diffuse to endocrine cells (parvocellular (small))

Question 15

describe the short and long feedback loop in hypothalamus that modulate endocrine function

Answer 15

long loop: testes and testosterone
short loop: GnRH, LH, FSH
LH and FSH stimulates the secretion of testes

short loop

1. hypothalamus release of releasing factors (GnRH) to anterior pituitary
2. anterior pituitary releases tropic hormone (LH, FSH)
3. tropic hormones act in the testes
4. tropic hormones feed back to hypothalamus to inhibit GnRH production

long loop
1 ~ 3 are the same
4. testes release hormone (testosterone) which inhibits GnRH production in hypothalamus

Question 16

pulsatile pattern

Answer 16

pulsatile pattern: receptor (saturated and) internalized, so no need to be constant high level

Question 17

thyroid disorder

Answer 17

Hypothyroidism

• Depression
• Fatigue
• Weigh gain

Hyperthyroidism
- Nervousness
- Heart palpitations
- Weight loss
- Most common cause: Grave’s Disease
(antibodies against TSH Receptors)

Question 18

what happens to LH/FSH levels when someone is taking anabolic steroids?

Answer 18

1. drop in LH/FSH

2. less sperm produced

Question 19

what happens to LH/FSH when a man is castrated?

Answer 19

1. no testes
2. low testosterone count
3. not a lot of long feedback
4. hypothalamus overactive
5. high LH/FSH levels

Question 20

describe female reproduction cycle

Answer 20

1. estrogen primes the brain to respond to progesterone

2. estrogen receptor in VMH is necessary for female sexual behavior

Question 21

evolution of prolactin function

Answer 21

Prolactin help milk secretion in mammals;
in birds, but hep milk secretion and brain to give the milk;
concept: hormone both engage in both pituitary gland and brain

Question 22

steroid receptor distribution in the rat brain

Answer 22

the MPOA and VMH (lateral zone) integrate endocrine and sensory information to modulate reproductive behavior (synchronized behavior with fertility)

Question 23

sexually dimorphic nucleus of the pre optic area

Answer 23

gonadectomize at different stages (P0 and P90);

organization vs activation