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Flashcards in Endocrine System Deck (72)
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1

Glands

organs that secrete hormones

2

Hormones

signaling molecules that are secreted directly into the bloodstream to travel to target tissue

3

Peptide Hormones

-made up of amino acids
-derived from larger precursor polypeptides that are cleaved during posttranslational modifications
-charged and cannot pass through plasma membrane so must bind to an extracellular receptor
-considered a first messenger b/c it binds to a receptor and triggers the transmission of a second signal/messenger
-effects are rapid but short-lived b/c act through transient second messenger systems
-generally water soluble and can travel freely in bloodstream

4

Signaling Cascade

the connection between the hormone at the surface and the effect brought about by second messengers within the cell

5

List common second messengers (3)

-cAMP
-IP3
-calcium

6

Steroid Hormones

-derived from cholesterol
-produced primarily by the gonads and adrenal cortex
-nonpolar molecules that can easily cross plasma membrane
-receptors are intracellular (in the cytosol) or intranuclear (in the nucleus) and after binding they form a hormone-receptor complex that binds to DNA to alter gene expression
-effects of hormone are slower but last longer
-cause alterations in amount of mRNA and protein present in cell
-not water soluble so carried by proteins in bloodstream
-includes: estrogen, testosterone, aldosterone, cortisol glucocorticoids

7

Dimerization

pairing of two receptor hormone complexes

8

Amino-Acid Derivative Hormones

-includes: epinephrine, norepinephrine, triiodothyronine, thyroxine
-catecholamines are a type of these

9

Catecholamines

-includes: epinephrine, norepinephrine
-bind to G protein coupled receptors
-important in long-term stress responses

10

Direct Hormones

secreted and then act directly on a target tissue

11

Tropic Hormones

-require an intermediary to act
-do not cause a direct change in physiology of tissue but do stimulate production of another hormone by another endocrine gland that acts on the target tissue
-originate in the brain and anterior pituitary gland

12

Hypothalamus

-bridge between nervous and endocrine system
-located in the forebrain directly above pituitary gland and below thalamus
-regulates pituitary gland through tropic hormones via paracrine release of hormones into a portal system that connects the two organs

13

How does the hypothalamus interact with the anterior pituitary gland?

-secretes compounds into the hypophyseal portal system (blood vessel that directly connects hypothalamus to anterior pituitary)
-hormones can be found in appreciable concentrations in systemic circulation

14

List of hormones secreted by hypothalamus and response anterior pituitary hormones (4)

-gonadotropin-releasing hormone (GnRH) -> follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
-growth hormone-releasing hormone (GHRH) -> growth hormone (GH)
-thyroid releasing hormone (TRH) -> thyroid stimulating hormone (TSH)
-corticotropin-releasing factor (CRF) -> adrenocorticotropic hormone (ACTH)

15

What is different about Prolactin?

-almost all other hormones cause an increase in anterior pituitary secretion but this hormone causes a decrease
-prolactin-inhibitory factor (PIF) which is actually dopamine is released by hypothalamus and causes a decrease in prolactin secretion by the anterior pituitary

16

Posterior Pituitary Gland

-neurons from hypothalamus send their axons down the pituitary stalk directly to this gland
-essentially an extension of the hypothalamus
-hormones released here: oxytocin, antidiuretic hormone/vasopressin
-doesn't synthesize any hormones itself, just stores them

17

Oxytocin

-stimulates uterine contractions during labor and milk letdown during lactation
-involved in bonding behavior with baby
-positive feedback loop
-source: hypothalamus (stored in posterior pituitary)

18

Antidiuretic Hormone (ADH)

-increases reabsorption of water in collecting ducts of kidneys
-secreted in response to increased plasma osmolarity or increased concentration of solutes within the blood
-source: hypothalamus (stored in posterior pituitary)

19

List the 7 hormones that are synthesized/secreted by the anterior pituitary gland

*FLAT PEG*
-Follicle-stimulating hormone
-Luteinizing hormone
-Adrenocorticotropic hormone
-Thyroid stimulating hormone
-Prolactin
-Endorphins
-Growth hormone

20

What anterior pituitary hormones are tropic hormones?

*FLAT*
-Follicle-stimulating hormone
-Luteinizing hormone
-Adrenocorticotropic hormone
-Thyroid stimulating hormone

21

What anterior pituitary hormones are direct hormones?

*PEG*
-Prolactin
-Endorphins
-Growth hormone

22

Prolactin

-stimulates milk production in the mammary glands
-release of dopamine from hypothalamus decreases its secretion from anterior pituitary

23

Growth Hormone

-promotes growth of bone and muscle
-prevents glucose uptake in tissues that aren't growing and stimulates breakdown of fatty acids which increases availability of glucose overall allowing for muscle and bone to use it

24

Where does bone growth originate?

epiphyseal plates

25

What is the cause of gigantism?

excess GH release in childhood

26

What is the cause of dwarfism?

deficit in GH release during childhood

27

What is acromegaly?

-when there is excess GH production in adults and they develop large hands + feet + head
-occurs because small bones can still be affected by GH later in life whereas long bones cannot

28

Follicule Stimulating Hormone (FSH)

-stimulates follicle maturation
-stimulates spermatogenesis
-source: anterior pituitary

29

Luteinizing Hormone (LH)

-stimulates ovulation
-stimulates testosterone synthesis
-source: anterior pituitary

30

Adrenocorticotropic Hormone (ACTH)

-stimulates adrenal cortex to make and secrete glucocorticoids (anti-inflammatory)
-source: anterior pituitary