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Flashcards in Endocrine Physiology Deck (26)
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1

Hormone

- chemical messenger
- secreted from ductless gland
- emptied directly into circulation
- transported by blood to alter target organ
- present in small concentrations

2

Endocrine system

Glands that release hormones into circulation
- helps establish systemic homeostasis

3

What 3 things does the endocrine system regulate?

- metabolism
- growth and development
- mood

4

Endocrine glands

- hypothalamus
- pituitary
- thyroid
- parathyroid
- adrenal
- pancreas
- repro (ovary, testicle, placenta, mammary)
- kidneys
- GIT

5

Hormone structure affects

- function
- transport
- interaction with target cell

6

Protein hormones

Mostly go to the brain
- dissolved in blood: hydrophilic, no carrier needed
- receptors on plasma membrane

7

Hypothalamic protein hormones

- TRH
- CRH

8

Pituitary protein hormones

- TSH, ACTH
- growth hormone
- vasopressin
- oxytocin

9

Amine hormones

Derived from tyrosine
- thyroid hormones
- transported bound to proteins (99%) --> lipophilic
- only free form is active
- bound protein isn't excreted
- receptors: intracellular

10

Steroid hormones

Derived from cholesterol
- transported bound to proteins --> lipophilic
- only free form is active
- receptors: cytosolic, nuclear
- cortisol
- sex hormones

11

Feedback control

Regulation of hormonal secretion from an endocrine gland by an effect of the circulating hormone that the gland itself produces

12

Negative feedback

Increased hormone concentrations result in less production of the hormone, usually through an interaction with the hypothalamus or pituitary gland

13

Negative feedback example (thyroid)

Higher thyroid hormone concentrations decrease release of stimulatory and releasing hormones (TSH, TRH)
- decreased release of stimulatory and releasing hormones results in decreased synthesis of T4

14

_____ of hormone production results in increased release of ______

Lack; sitmulatory hormones

15

The hypothalamus is part of the _______

Diencephalon
- forms floor of 3rd ventricle

16

Anterior versus posterior pituitary

Anterior: adenohypophysis
- glandular
- pars distalis/tuberalis/intermedia
Posterior: neurohypophysis
- neural tissue

17

AP embryology

- Rathke's pouch
- invagination of pharyngeal epithelium
- epithelioid cells

18

PP embryology

- neural outgrowth from hypothalamus
- neural tissue

19

Hypothalamic/pituitary relationship

- hypothalamus controls release of pituitary hormones
- AP: releases hormones/inhibitory hormones
- PP: neuronal control

20

How does the hypothalamus receive signals from the brain?

- break in BBB
- fenestrated capillaries allow sampling of chemicals in the blood

21

Median eminence

Lower-most portion of HT
- connects with pituitary stalk
- arteries penetrate ME
- HT blood flows thru ME directly to AP
- HT hormones released into ME

22

Magnocellular

"Large neurons"
- cell bodies of PP in HT
- supraoptic nuclei (ADH)
- paraventricular nuclei (oxytocin)
- axons terminate in PP

23

Hormones secreted from PP neurons

Transported down nerve fibers
- released into surrounding capillaries

24

Anterior pituitary hormones

- corticotropes (20%): ACTH
- thyrotropes (4%): TSH
- somatotropes (30-40%): growth hormones --> acidophils
- lactotropes (4%): prolactin
- gonadotropes (4%): FSH, LH

25

Antidiuretic hormone

Aka: vasopressin
- regulates free water excretion from kidneys
- blood pressure

26

Oxytocin

- milk expression
- birth
- orgasm