Hypothalamus

Front 1

Where is the hypothalamus located?

Back 1

It is the most ventral part of the diencephalon, lying beneath the thalamus.

Front 2

What is the function/role of the HT?

Back 2

The HT is involved in mediation of endocrine, autonomic and behavioural functions.

The hypothalamus controls the release of 3 major hormones by the pituitary gland. It is involved in temperature regulation, control of food and water intake, sexual behaviour and reproduction and mediation of emotional responses

Front 3

What are the three major hypothalamic cell groups?

Back 3

The three major hypothalamic cell groups are the periventricular zone, medial zone and the lateral zone

Front 4

What is the role of the periventricular zone?

Back 4

The periventricular zone is the most medial zone and is comprised of thin nuclei that border the third ventricle.

This zone is important in regulating the release of endocrine hormones from the anterior pituitary gland

Front 5

What is the role of the middle zone?

Back 5

The middle zone has a variety of functions. It is the major site for neurons that regulate the autonomic nervous system.

Front 6

What is the role of the lateral zone?

Back 6

The lateral zone contains neurones that integrate information from the limbic system and trasmit this information to other parts of the HT as well as the midbrain. This zone is important in emotions and their behavioural expression

Front 7

What is the role of mammillary bodies play?

Back 7

They play an important role in human memory functioning

Front 8

What are magnocellular neurons?

Back 8

They are large neuroendocrine neurones that originate from the supraoptic nucleus and paraventricular nucleus of the HT. They release hormones into the general circulation through the posterior PG

Front 9

What are parvocellular neurons?

Back 9

They are small neurones within the paraventricular nucleus of the hypothalamus. They release chemical signals into the into the capillary bed of the pituitary portal system that then control the release of hormones from the anterior PG.

Front 10

There are two types of magnocellular neurons, what are they?

Back 10

Oxytocin-producing and vasopressin-producing cells.

Front 11

Where are the supraoptic nucleus and paraventricular nucleus located?

Back 11

The supraoptic nucleus is located in the lateral zone

the paraventricular nucleus is located in the periventricular zone

Front 12

Name the two anatomically different parts of the pituitary gland. What makes them different?

Back 12

The anterior pituitary gland and the posterior pituitary gland

The posterior PG is a neural structure and the anterior PG is not.

Front 13

What hormone does the supraoptic nucleus release?

Back 13

Vasopressin

Front 14

What is the effect of vasopressin ?

Back 14

Increases water reabsorption by the kidney

Front 15

What hormone does the paraventricular nucleus produce?

Back 15

Oxytocin

Front 16

What effect for oxytocin have?

Back 16

Increased oxytocin leads to inhibition:

-fighting

-freezing

-fleeing

This is because oxytocin leads to inhibition of amygdala and ANS.

Front 17

Where do the axons of the supraoptic and paraventricular terminate?

Back 17

They terminate at the posterior pituitary gland and release the hormone onto the capillary bed where it enter the general circulation

Front 18

what are the inputs to the HT?

Back 18

Both circulatory and neural in origin

The circulating blood provides physical (osmolality), chemical (blood glucose) and hormone signals, which provide information about the state of the body

Front 19

Does the supraoptic nucleus contains osmosensitive neurones that are activated by changes is osmolality of circulating blood?

Back 19

yes

Front 20

What happens when there is an increase in osmolality of the blood?

Back 20

The supraoptic nucleus osmosensitive neurones detect this change and this results in the activation of the magnocellular neurones of the supraspinal nucleus, causing an increase in water absorption by the kidneys

Front 21

Releasing factors and release inhibiting factors. They are synthesised by the HT. They control release of hormones from the anterior PG. Is this true?

Back 21

True

Front 22

What hormones are released by the anterior PG?

Back 22

ACTH, LH/FSH, GH, TSH and Prolactin are released into the general circulation by anterior PG

Front 23

What is the mechanism for the release of the hormones from the anterior PG, by release factors?

Back 23

The factors that control release of hormones are released from the terminals of the hypothalamic neurones into the capillary bed of the pituitary portal system, these factors then control release of hormones from the anterior PG into the general circulation

Front 24

When is oxytocin released?

Back 24

There is an increase of oxytocin in social settings.

Front 25

How does the HT play a key role in controlling food intake/feeding habits?

Back 25

By sensing metabolic signals from the peripheral organs

Front 26

What are adiposity signals? Give two examples

Back 26

Factors that circulate in proportion to body fat mass. Two important examples are insulin and leptin.

Front 27

What are satiety signals?

Back 27

Signals generated during a meal are termed satiety factors. They are secreted from the GI tract in response to food in the lumen.

Front 28

What is the role of the arcuate nucleus?

Back 28

It has a key role in the regulation of feeding behaviour

Front 29

What is an adipocyte?

Back 29

A cell specialised for storage of fat

Front 30

What are the two distinct groups of neurones?

Back 30

One group is neurones coexpress neuropeptide Y (NPY) and the other subset of neurones express proopopmelanocortin (POMC).

Front 31

One group is neurones coexpress neuropeptide Y (NPY) and the other subset of neurones express proopopmelanocortin (POMC). These are called first order neurones.

Back 31

True. These neurones are where the metabolic signals are detected.

Front 32

Where do POMC neurones project to?

Back 32

They project to second-order neurones in other hypothalamic areas: PVN

Front 33

Where do the NPY neurones project to?

Back 33

They project to second-order neurones in other hypothalamic areas: LHA and PFA

Front 34

What does NPY release from NPY neurones in the PVN and PFA cause?

Back 34

It stimulates eating by activating the anabolic pathway and inhibiting the catabolic pathway

Front 35

What does aplha-MSH release from POMC neurones in the PVN and LHA cause?

Back 35

It has an anorexic effect by activating the catabolic pathway and inhibiting the anabolic pathway.

Front 36

Leptin and insulin inhibit the anabolic pathway and stimulate the catabolic pathway.

Back 36

True

Front 37

How are inputs to satiety transmitted and processed?

Back 37

Afferent inputs related to satiety from the GI tract are transmitted through the vagus nerve to the NTS. There they are integrated with descending hypothalamic input (anabolic/catabolic pathways).

Front 38

How are the integrated adiposity and satiety signals processed at the NTS?

Back 38

Net neuronal output from the NTS leads to the termination of meals. The NTS is activated by the catabolic pathway and inhibited by the anabolic pathway. And increased satiety signals stimulate the NTS.