Lecture 1: Introduction to the hypothalamus

Question 1

What is the Hypo thalamus pituitary target organ axis? What substances are released from where?

Answer 1

• CNS –> hypothalamus –> pituitary –> target organs
• Hypothalamus releases GnRH
• Pituitary releases FSH/LH
• Target organs release testosterone and estrogen

Question 2

The hierachical arrangement of endocrine glands allows (3)?

Answer 2

• Amplification
• Propagation
• Intergration

Question 3

Connections between hypothalamus and anterior and posterior pituitary?

Answer 3

• Hypo –> Anterior connection is Humoral portal blood system
• Hypo –> posterior is neural connection

Question 4

Outputs of the lobes of the pituitary?

Answer 4

• Anterior releases gonadotrophs
• Posterior releases oxytocin

Question 5

Inputs into the hypothalamus and influence?

Answer 5

• Light - seasonal breeding (not really a thing in humans)
• Smell - pheromones?
• Touch - oxytocin released by touch on nipples for breast feeding
• Sound - baby crying –> oxytocin
• Stress - decreased release (amenohhrea)

Question 6

feedback systems within the H/P/G axis

Answer 6

• Short loop feedback and long loop feedback
• primarily negative feedback loops

Question 7

H/P/G axis hormones are released in a _____ way, why?

Answer 7

• Pulsatile - allows increased information to be carried through the frequency and amplitude of the signals
• Allows prevents desensitization?

Question 8

Origin of the hypothalamus

Answer 8

• Comes from a swelling of the diancephalon

Question 9

Location, size, shape of the hypothalamus?

Answer 9

• Located in the diancephalon beneath the base of the forebrain
• apox 4g of tissue
• Funnel shaped structure ending with a solid stalk of neurons

Question 10

Composition of the hypothalamus?

Answer 10

• Cell bodys + axons + hypothalamic neurons
• axons + terminals of neurons whose cell bodies are outside the hypothalamus
• Glial cells
• Blood vessels

Question 11

supraoptic and paraventricular nuclei?

Answer 11

• Paired
• Magnocellular
• releases ADH and oxytocin
• –> pars nervosa

Question 12

Arcuate (infundibular) nuclei

Answer 12

• parvicellular
• GnRH
• –> anterior pituitary

Question 13

Horomones released by parvicellular nuclei?

Answer 13

• GnRH
• TRH
• GHRH
• GHIH (somatostatin)
• PIF (dopamine)
• CRH