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Flashcards in Pituitary gland and hypothalamus Deck (46)
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1

What is the pituitary gland known as?

The master of all endocrine galnds

2

What are structural properties of the pituitary gland?

Size of a pea - 0.5g

Sits at the bottom of the brain -> sella turcica

Broad division into the anterior and posterior pituitary

Pituitary and hypothalamus are one unit -> division relates to how it interacts with the hypothalamus

3

Why are pituitary adenomas often linked to loss of visual acuity?

The pituitary sits adjacet to the branches of the optic nerve

Some of the branches cross over at the levels of the pituitary

Compression of aspects of the optic chiasm if the pituitary expands

4

What characterises the posterior from the anterior pituitary?

The way they interact with the hypothalamus is different

5

What is another name for the anterior pituitary?

Adenophysis

6

How does the hypothalamus communicate to the anterior pituitary?

Anterior pituitary is under the control of hormones (peptides) released by the hypothalamus

Neurosecretory neurons from the hypothalamus secrete the hormones into the venous system that connect the two structures

7

What is the venous system that joins the adenophysis to the hypothalamus called?

Hypophyseal portal system

8

How does the hypothalamus communicate to the posterioi pituitary?

Nervous system

The posterior pituitary is innervated by neurones from the hypothalamus

9

What are the two hormones released from the posterior pituitary?

ADH

Oxytocin

10

When are hormones released from the posterior pituitary?

In situations of stress

11

What are 5 hormones released by the anterior pituitary?

Growth hormone
Thyroid stimulating hormone
Prolactin
ACTH
LH and FSH

12

What are hormones released by the hypothalamus that acts on the anterior pituitary?

Growth hormone releasing hormone
Thyroid releasing hormone
CRH
GnRH

13

What happens in the hypothalamic pituitary thyroid axis?

1. TRH is released from the hypothalamus

2. Stimulates the anterior pituitary to release TSH

3. Acts on the thyroid to release T3 and T4

14

How is TRH release regulated?

In a dional fashion. High and low concentrations throughout the say. Many nervous stimuli affects its release.

15

Features of TRH

Thyrotropin releasing hormone

Highly stable

Tripeptide amine

Rapidly degraded by plasma

16

Where can dysregulation in the thyroid axis happen?

In 3 areas:

Thyroid gland - primary thyroid problem

Pituitary gland - secondary thyroid problem

Hypothalamus - tertiary thyroid problem

17

Where is GnRH released from?

The hypothalamus

18

What is released when GnRH stimulates the anterior pituitary?

LH - Leutinizing hormone

FSH - Follicle stimulating hormone

19

What is LH and FSH involved in?

Development of secondary sexual characteristics

20

In what pattern is GnRH released?

Pulsatile release

21

What would happen if GnRH would be released constantly?

Cause the suppression of FSH and LH

Downregulation of receptors to GnRH on the pituitary

Can be used therapeutically to treat:

1. Early puberty - constant GnRH to suppress LH and FSH receptors

2. Cancer responsive to hormones - testosterone in prostate and oestrogen in breast cancer

22

What conditions can affect the concentration of hormones released by the pituitary?

Gender

State of developmental activity

How much the pituitary has been stimulated

23

What happens if GnRH is released under the right conditions and stimuli?

Spermatogenesis in males

Ovulation in females

24

What hormone is released from the hypothalamus to stimulate GH secretion?

Growth hormone releasing hormone

GHRH

25

What two ways are there of measuring growth?

Hypertrophy - cells get bigger

Hyperplasia - more cells

26

What conditions are related to GH dysregulation?

Acromegaly

Pituitary adenoma

Some types of Dwarfism

27

How do pituitary adenomas dysregulate GH secretion?

Increased GH secretion by the anterior pituitary

Can also release other hormones like prolactin and ACTH

Adenomas are classified by their size

Less than 10 mm -> microadenoma
More than 10mm -> macroadenoma

28

Pathogenesis of acromegaly

Excess release of GH from the pituitary

Symptoms:

Excess growth of soft tissues
Metabolic abnormalities - diabetes
Linear growth
Galactorrhea - abnormal prolactin signalling

29

How does a dysregulation of GH from pituitary lead to dwarfism?

GH resistance or receptor to GH is mutated

30

What hormone acts as a negative regulator of GH release?

Somatostatin