Chapter 5 - Endocrine System Flashcards Preview

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Flashcards in Chapter 5 - Endocrine System Deck (79)
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1

What can diabetes lead to if not controlled?
(5)

Blindness
Kidney failure
Heart attack
Stroke
Amputation

2

What is it that hormones do?

They bind to receptions in the target tissue, inducing a change in gene expression or cellular functioning.

3

3 classifications of hormones by CHEMICAL structure

1. Peptide hormones
2. Steroid hormones
3. Amino-Acid Derivative hormones

4

What are peptide hormones made from?

Derived from larger polypeptides that are cleaved during post translational modification.

They are made up of amino acids

5

How does a cell make peptide hormones?

Polypeptides are broken down

Smaller units go to the Golgi apparatus for modifications that ACTIVATE the hormone

Packages into vesicles and sent out of the cell via exocytosis

6

Can peptide hormones pass through the cell membrane?

Why / why not?

What are first / second messengers?

NO because they are charged.

They must hence bind to an exta cellular receptor. (Often a g-protein coupled receptor)

First messenger is the hormone - second messenger is within the cell. This is known as signaling cascade.

7

Examples of common second messengers?

Cyclic adenosine monophasphate (cAMP) -- am regulated by enzyme called adenylate cyclase

Inositol triphosphate (IP3)

Calcium

8

Characteristics of peptide hormones:

Fast response?
Soluble?
Need carrier in bloodstream?

Fast response but short-lived (require constant stimulation of second messengers to continue the response)

Water-soluble

Do not need a carrier in the bloodstream

9

What are steroid hormones made from?

Cholesterol

Produced primarily by the gonads and adrenal cortex

10

Can steroid hormones pass through the cell membrane?

Why / why not?

Yes - because they are nonpolar

They don't require an extra cellular receptor (receptor is intercellular, in cytosol or in the nucleus)

11

How does a steroid hormone communicate with target cell/tissue?

Crosses membrane

Binds to receptor inside the cell

Steroid hormone-receptor complex undergoes CONFORMATIONAL CHANGES

Receptor can then bind directly to DNA

Increases or decreases transcription of particular genes

12

Characteristics of steroid hormones:

Fast acting?
Soluble?
Carrier in bloodstream?

Slow acting but long-lasting (because they cause alterations in the amount of mRNA and protein present in the cell)

Non-soluble

Carried by proteins in the blood stream

13

Common carriers of steroid hormones:

Sex-hormone-binding globulin (specific)
Albumin (nonspecific)
Thyroxine-binding globulin (TBG)

14

What are amino-acid derivative hormones made from?

An example?

Made from one or two amino acids, usually with additional modifications

Eg: thyroid hormones are made from tyrosine with the additional of iodine atoms

15

What are common examples of amino-acid derivative hormones:
(4)
Long or short duration? Fast or slow?

Epinephrine
Norepinephrine
Triiodothyronine
Thyroxine

First two: think "adrenaline rush" fast onset but short lived
Last two: slow onset and longer duration (regulate metabolic rate over a long period of time)

16

What are catecholamines?

What do they bind to?

Epinephrine and norepinephrine

Bind to g-protein-couples receptors (like peptide hormones)

17

What do thyroid hormones bind to?

They bind intracellularly, like steroid hormones

18

Direct versus Tropic hormones?

DIRECT
Act directly on target tissue

TROPIC
Requires an intermediary
Usually originate in the brain and anterior pituitary gland

Eg: GnRH (gonadotropin-releasing hormone) and LH do not cause direct changes; they stimulate the production of another hormone by another endocrine gland.

19

What is the purpose of the endocrine system?

To use hormones and messengers to create changes in behavior and physiology to maintain homeostasis

20

High blood glucose can cause damage to which organs:
(5)

Retina of the eye (blindness)
Glomeruli of the kidneys (kidney failure)
Coronary vessels of the heart (heart attack)
Cerebral vessels of the brain (stroke)
Nerve damage in extremities (amputation)

21

Why are thyroid hormone levels higher in pregnant women?

Because high levels of estrogen and progesterone increase the production of TBG (thyroxine-binding globulin). Secretion of thyroid hormones is increased to compensate.

This is an example of a change in level of carrier protein (globulin increase) which sides a change in the level of the active hormone.

22

What systems does the hypothalamus connect?

What other endocrine gland(s) does it interact with? (2)

What else does the hypothalamus regulate? (2)

Connect nervous and endocrine systems. Located in the forebrain

Anterior pituitary
Posterior pituitary

Responds to increases in blood osmolarity, and regulated appetite/satiety

23

What is the suprachiasmatic nucleus?

A part of the hypothalamus

Received light input from the retinas, helps control sleep-wake cycles

24

What is the hypophyseal portal system?

A blood vessel system that directly connects the anterior pituitary and the hypothalamus.

25

Which hormones produced by the hypothalamus cause a response in secretions from the ANTERIOR PITUITARY? (5)

1. GnRH - gonadotropin releasing hormone.

2. GHRH - growth hormone releasing hormone (ALSO somatostatin, also affects GH)

3. TRH - thyroid releasing hormone

4. CRF - Corticotropin-releasing factor

5. Dopamine aka PIF - prolactin inhibiting factor (this is the only one that causes a decrease in secretion from the pituitary)

26

What is an "axis" or three-organ system?

When the organs have receptors (ie cortisol receptors) to detect when high levels of cortisol in the blood have been obtained - cortisol can then inhibit the hypothalamus and Ant Pit from producing more hormones stimulating cortisol.

This is the Hypothalamic-pituitary-adrenal (HPA) axis

There is also the hypothalamic-pituitary-ovarian (HPO) axis, etc

27

How does the hypothalamus interact with the posterior pituitary?

What (2) hormones are release from the posterior pituitary (produced in the hypothalamus)?

Neurons in the hypothalamus send their axons down the pituitary stalk directly to the posterior pituitary.

1. Oxytocin

2. Antidiuretic hormone (ADH) aka Vasopressin

28

What is osmolarity?

Increased concentration of SOLUTES in the blood

29

Hormones secreted by the Anterior pituitary?

FLATPEG

FSH
LH
Adenocoeticotropic hormone ACTH
Thyroid stimulating hormone TSH
Prolactin
Endorphins
Growth hormone

FLAT are Tropic hormones
PEG are direct hormones

30

What does OXYTOCIN do?

Stimulates uterine contractions during labor
Stimulates milk letdown during lactation
May be involved in bonding behavior

*positive feedback mechanism