Hypothalamus and Pituitary

Question 1

Name the parts of the Hypothalamic/Pituitary/Gonadal axis:

Hypothalamic Hormone:

Anterior Pituitary Hormone:

Target Organ:

Target Organ Hormone:

Answer 1

Hypothalamic Hormone: GnRH (Gonadotrophin Releasing Hormone)

Anterior Pituitary Hormone: FSH/LH

Target Organ: Ovary/Testis

Target Organ Hormone: Estradiol/Testosterone

Question 2

The hypothalamus receives input from the ______. It relays information to the anterior pituitary via a _______ pathway and to the posterior pituitary via a _______ pathway.

The posterior pituitary releases _______ to target organs and the anterior pituitary releases ________ to the gonads (ovary/testis).

The gonads release sex hormones (______/______) to the target organs as well as the ______ and the _______.

Answer 2

The hypothalamus receives input from the CNS. It relays information to the anterior pituitary via a Humoral (vascular) pathway and to the posterior pituitary via a Neural pathway.

The posterior pituitary releases Oxytocin to target organs and the anterior pituitary releases Gonadotrophins (FSH/LH) to the gonads (ovary/testis).

The gonads release sex hormones (Estradiol/Testosterone) to the target organs as well as the Hypothalamus and the Anterior Pituitary.

Question 3

Name the 6 CNS inputs to the hypothalamus

Answer 3

1. Light (seasonal breeding - not really in humans)

2. Sound (mothers can lactate when they hear baby cry

3. Smell pheromones - unfounded

4. Touch (lactaction)

5. Psycho-Social (pain/stress can lead to amenhorrhea)

6. Nutritional Status (low body weight [<47kg] inhibits the menstrual cycle)

Question 4

Neurosecretion

Hormones are produced by ______ cells. They are packaged up into ______ and travel down the _______ where they enter the bloodstream in the _______ pituitary.

Answer 4

Neurosecretion

Hormones are produced by neural cells. They are packaged up into granules and travel down the axon where they enter the bloodstream in the posterior pituitary

Question 5

Feedback Systems in the Hypothalamus/Pituitary/Gonads

Most feedback loops are _______ but can sometimes can be _______.

A feedback system involving hormones released by the Gonads acting on the hypothalamus or CNS would be called ________ and hormones acting on the Anterior pituitary would be _______.

Answer 5

Feedback Systems in the Hypothalamus/Pituitary/Gonads

Most feedback loops are negative but can sometimes can be positive.

A feedback system involving hormones released by the Gonads acting on the hypothalamus or CNS would be called long loop (acting far upstream) and hormones acting on the Anterior pituitary would be short loop (only acting a little bit upstream).

Question 6

Hormones (e.g LH) are secreted in the form of a _______ release.

Information is contained both in the ________ and the _______ of the release.

Answer 6

Hormones (e.g LH) are secreted in the form of a pulsatile release.

Information is contained both in the amplitude (how much hormone is released at a time) and the frequency (how often the hormone is released) of the release.

Question 7

Hypothalamus

The hypothalamus originates from the _______ (the hindmost part of the forebrain [the base]).

It weighs ___ grams and is connected to the _________ via the _________.

Answer 7

Hypothalamus

The hypothalamus originates from the diencephalon (the hindmost part of the forebrain [the base]).

It weighs 4 grams and is connected to the pituitary via the infundibulum.

Question 8

Label the image

Answer 8

This is the image.

[mb] = mamillary body

[lt] = lamina terminalis

Question 9

Clusters of hypothalamic neuronal cell bodies in the wall of the hypothalamus are called Hypothalamic ________. These clusters are where ________ are produced.

The important magnocellular nuclei are the ______ and the _______ nuclei. The hormones that they produce are _______ and _______ which travel to the pars _______ of the pituitary.

The other important nuclei are the _______ nuclei (small cells). The main nucleus is called the _______ nucleus which produces GnRH, PIF and more. Instead of synapsing on the pituitary, these neurons release hormones onto ________ at the upper and lower _______ _______ which take them to the _______ pituitary (pars ______). This is the ________ system.

Answer 9

Clusters of hypothalamic neuronal cell bodies in the wall of the hypothalamus are called Hypothalamic Nuclei. These clusters are where hormones are produced.

The important magnocellular nuclei are the supraoptic nuclei and the paraventricular nuclei (both are paired). The hormones that they produce are Vasopressin (ADH) and Oxytocin which travel to the pars nervosa (posterior pituitary) of the pituitary.

The other important nuclei are the parvicellular nuclei (small cells). The main nucleus is called the arcuate nucleus which produces GnRH, PIF and more. Instead of synapsing on the pituitary, these neurons release hormones onto capillaries at the upper and lower infundibular stalk which take them to the anterior pituitary (pars distalis). This is the humoral/portal system.

Question 10

Label this nice diagram:

(Bonus Question: Which part of the pituitary is the anterior lobe and which part is the posterior lobe?)

Answer 10

Here is the nice labeled diagram:

[son] supraoptic nucleus

[pvn] paraventricular nucleus

Anterior Lobe: pars tuberalis and pars distalis

Posterior Lobe: pars nervosa

Question 11

What constitutes the neurohypophysis?

Answer 11

Median Eminence

Infundibular Stalk

Infundibular Process (pars nervosa)

Question 12

What constitutes the adenohypophysis?

Answer 12

pars tuberalis

pars distalis

Question 13

Label this diagram pls

Answer 13

Question 14

Another name for pars nervosa?

Answer 14

Infundibular Process

Question 15

The pituitary is immediately encapsulated in a fibrous membrane called the ________. The part of this which covers the superior portition between the sella turcica is called the ________.

Answer 15

The pituitary is immediately encapsulated in a fibrous membrane called the dura mater. The part of this which covers the superior portition between the sella turcica is called the diaphragma sella.

Question 16

Embryology of Pituitary.

The anterior pituitary (pars ______ and pars ______) are formed from an inbudding of tissue; ______, which comes from the______ in the embryo.

The posterior pituitary (pars ______) comes from the hindmost part of the forebrain, which grows down to form the _______ in the embryo and gives rise to the _______ and _______ in adults.

This means that the anterior pituitary is of _______ origin and the posterior pituitary is of ________ origin.

Answer 16

Embryology of Pituitary.

The anterior pituitary (pars tuberalis and pars distalis) are formed from an inbudding of tissue; Rathke’s Pouch, which comes from the stomodeum (primitive mouth cavity) in the embryo.

The posterior pituitary (pars nervosa) comes from the hindmost part of the forebrain, which grows down to form the neurohypophyseal bud in the embryo and gives rise to the posterior pituitary and infundibular stalk in adults.

This means that the anterior pituitary is of epithelial origin and the posterior pituitary is of neural origin.

Question 17

Match the Anterior Pituitary hormones with the Hypothalmus hormones

Answer 17

Match the Anterior Pituitary hormones with the Hypothalmus hormones