Chapter Four: Hypothalamic Hormones

Question 1

Functions of the hypothalamus

Answer 1

1. Neuroendocrine
2. Visceral (ANS)
3. Motivational (hunger, thirst, agression, sex)
4. Emotional (limbic system)
5. Behavioural (CNS)
6. Biological clock
7. Immune system

Question 2

Tropic vs. trophic

Answer 2

Tropic - have a stimulatory effect on a gland

Trophic - have a stimulatory effect on a tissue

Question 3

Afferents (information coming into the hypothalamus)

Answer 3

1. Cortical
2. Visceral
3. Olfactory
4. Visual
5. Somatosensory
6. Auditory
7. Limbic

Question 4

Magnocellular system

Answer 4

Large magnocellular neurosecretory cells are located in the PVN and SON

Question 5

Parvicellular system

Answer 5

Small neurosecretory cells in the PVN, preoptic area, project to medial eminence

Question 6

Endocrine hypothalamus

Answer 6

Ventromedial nucleus, arcuate nucleus, medial eminence

Question 7

Four types of neuroendocrine transducers

Answer 7

1. PVN/SON (oxytocin, vasopressin)
2. Parvicellular (releases inhibiting hormones)
3. Adrenal medulla (epinepherine, norepinepherine)
4. Pineal gland

Question 8

Neuroendocrine transduction

Answer 8

Hypothalamic neurosecretory cells are stimulated by neurotransmitters to release their hormones

Converting neuron input to hormonal output

Question 9

SON Supraoptic nuclei

Answer 9

Synthesis of ADH, oxytocin, neurophysins from the magnocellular system

Regulates thirst

Synthesis of CRH (corticotropin releasing hormone) from the parvocellular division

Question 10

PVN

Answer 10

Synthesis of oxytocin, vasopressin and neurophysins from the magnocellular division

Synthesis of TRH and CRH from the parvicellular division

Question 11

SCN

Answer 11

Biological clock, regulates rhythmic release of glucocorticoids, melatonin

Regulates sleep-wake cycle

Question 12

Preoptic area and Anterior Hypothalamic: POA-AH

Answer 12

Synthesis of LH-RH, TRH (thyrotropin releasing hormone)

Stimulates LH-RH and PRL surges

PNS coordination

Temp regulation

Male sexual behaviour, female parental behaviour

Question 13

Ventromedial Nuclei

Answer 13

Synthesis of GH, SOM, CRF, prolactin, TRH

Detects blood glucose levels and regulates food intake

Regulates female sexual behaviour

Question 14

Arcuate Nucleus and median eminence

Answer 14

Synthesis of TRH, CRH, GH

LH nerve terminals

Dopamine released into portal veins

Question 15

Hypothalamic hypophysiotropic hormones

Answer 15

Thyrotropin releasing hormone - PVN

Corticotropin releasing hormone - PVN

Gonadotropin releasing hormone - POA-AH in rodents, ARC in humans

GH-RH growth hormone and GH-RIH growth inhibiting hormone

Prolactin releasing and inhibiting factors

MSH releasing and inhibiting factors

Question 16

Human menstrual cycle

Answer 16

FSH involved in stimulating follicle growth

Ovulation occurs with a surge of LH and GnRH

Question 17

GnRH levels

Answer 17

Phasic; released in bursts

GnRH is hard to detect, so LH is measured (as LH is released by GnRH)

Same in males and females

GnRH produced at a constant level in anorexic females which results in no menstrual cycle

Question 18

Complexities of hypothalamic/pituitary interactions

Answer 18

1. Hypothalamic hormones are multifunctional
2. Pituitary hormones may be transported back to the hypothalamus to act as neuromodulators
3. Not all hypothalamic hormones are secreted into the pituitary
4. Release of pituitary hormones may be regulated by neurotransmitters and hypothalamic hypophysiotropic hormones
5. Hypothalamic hormones interact with other hormones

Question 19

3 parts of the medial basal hypothalamus

Answer 19

Ventromedial hypothalamus, median eminence, arcuate nucleus