Neuroendocrine regulation and pituitary Flashcards

1
Q

What does the hypothalamus act on?

A

The pituitary gland.

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2
Q

What hormones can the pituitary gland release?

A

Hormones that can control the gonads, thyroid and adrenal gland.

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3
Q

What is the pituitary divided into?

A

The anterior and posterior pituitary.

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4
Q

How is ADH released?

A

It is modified by the hypothalamus and released from the posterior pituitary.

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5
Q

What is ADH involved in?

A

Regulating the volume of urine that is produced in the kidney.

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6
Q

What are some hormones released by the anterior pituitary gland?

A

Growth hormone, prolactin (released during pregnancy and stimulates mammary glands).

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7
Q

What are primary hormones?

A

Created by endocrine glands that into the circulation and reach their target tissues.

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8
Q

What is the neuroendocrine system?

A

Modified neuro secretory cells that release the hormones into the circulation that can travel to distant target cells.

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9
Q

Where is the hypothalamus located?

A

The base of the brain.

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10
Q

How are the hypothalamus and pituitary gland linked?

A

The pituitary gland is the hypothalamus’ output organ.

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11
Q

What is the median eminence?

A

The small capillary bed where regulatory hormones are released from the hypothalamus into the pituitary.

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12
Q

Where do hormones travel that are released into the median eminence?

A

They travel in the hypothalamo-pituitary portal vessels that then travel in the blood vessels directly to the anterior pituitary.

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13
Q

What does the paraventricular nucleus do?

A

It releases oxytocin that causes lactation.

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14
Q

What does the supraoptic nucleus do?

A

It release vasopressin (ADH).

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15
Q

WHat does the arcuate nucleus and periventricular zone do?

A

They are involved in neuroendocrine control.

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16
Q

What do suprachiasmatic neurones do?

A

Receive retinal innervation and synchronize circadian rhythms in the light-dark cycle and send output to sympathetic and parasympathetic output neurones in the spinal cord to control activity of the ANS.

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17
Q

What do neurosecretory cells do?

A

They are responsible for the release of regulatory hormone to control pituitary gland.

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18
Q

What are the key cells in the periventricular zone?

A

Suprachiasmatic neurones and neurosecretory cells.

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19
Q

How is the hypothalamus and anterior pituitary gland linked?

A

The hypothalamus produces regulatory hormones that stimulate or inhibit hormones produced by the anterior pituitary gland.

20
Q

What are some of the releasing factor hormones the hypothalamus releases?

A

Corticotropin releasing factor (CRF), thyrotropin releasing hormone (TRH), growth hormone releasing hormone (GHRH), gonadotropin releasing hormone (GnRH), prolactin releasing factor (PRF).

21
Q

What are some of the inhibiting factor hormones the hypothalamus releases?

A

Growth hormone inhibiting hormone (GHIH), prolactin inhibiting hormone (PIH) and melanocyte stimulating hormone inhibitng hormone (MSH-IH).

22
Q

What tissue makes up the posterior pituitary gland?

A

The pars nervosa, the pars intermedia and the pars distalis.

23
Q

What does the pars distalis do?

A

It contains stored hormones waiting to be released.

24
Q

What are the four trophic hormones that are released from the anterior pituitary?

A

Thyroid stimulating hormone (TSH), Adrenocorticotrophic hormone (ACTH), follicle stimulating hormone (FSH) and luteinizing hormone (LH).

25
Q

What are the two primary hormones the anterior pituitary releases?

A

Growth hormone (GH) and prolactin (PRL).

26
Q

How does the hypothalamus control the release of hormones from the anterior pituitary?

A

Hormones are secreted into the hypothalamic neurones that travel through the capillaries in the median eminence. Blood flow is driven by the heart and goes in one direction.

27
Q

What do hypophysiotropic hormones do?

A

They signal to the anterior pituitary to release a hormone, or prevent hormone release.

28
Q

What are the effects of growth hormone?

A
  1. Increases cell size, number and differentiation

2. By protein synthesis, fat utilization and altered carbohydrate metabolism.

29
Q

What is growth hormone?

A

A polypeptide hormone that acts at a receptor tyrosine kinase.

30
Q

What is growth hormone a major regulator of?

A

Post-natal growth.

31
Q

What are somatomedins?

A

Small proteins produced by the liver in response to growth hormone. There are at least 4 that are produced and they have a long half life compared to growth hormone (20 hours compared to less than 20 minutes).

32
Q

What does GH trigger the release of?

A

Somatomedins that cause an increase in cell size and number, differentiation, protein synthesis and bone growth.

33
Q

What is GH released in response to?

A

Growth-hormone-releasing hormone (GHRH).

34
Q

What is the release of GH inhibited by?

A

Growth-hormone-inhibiting hormone (GHIH/somatostatin).

35
Q

Where are GHRH and GHIH released from?

A

Ventromedial hypothalamus.

36
Q

When are surges of GH released?

A

Birth, puberty.

37
Q

When does GH release stabilise/decline?

A

Adulthood and old age.

38
Q

What metabolic signals affect GH?

A

Insulin-induced hypoglycaemia stimulates GH secretion.

39
Q

What other signals stimulate GH release?

A

Exercise and sleep.

40
Q

What does GH act on?

A

The liver.

41
Q

Why is GH important in the body?

A

WIthout it dwarfism may result or accelerated aging.

42
Q

What causes dwarfism?

A

General anterior pituitary dysfunction, specific GH deficit or normal but heriditary somatomedin deficit.

43
Q

What can an excess of GH cause?

A

GIgantism and acromegaly.

44
Q

What is acromegaly?

A

It is caused by an excess production of growth hormone and most commonly affects the middle-aged. It can result in premature death and it is infrequently diagnosed due to slow onset. Most common symptoms are abnormal growth of hand and feet.

45
Q

How can acromegaly be treated?

A

Surgical removal of a tumour, drug therapy or radiation therapy.

46
Q

What are produced as primary hormones from posterior pituitary

A
  1. ADH

2. Oxytocin