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Intro Bio II Exam 3 > Hormones > Flashcards

Hormones Flashcards

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1
Q

The endocrine system is composed of?

A

All hormone secreting tissues.

  • glands
  • tissues that secrete hormones that are not glands
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2
Q

3 ways that hormones act

A
  • control the rate of enzymatic reactions
  • control the transport of ions or molecules across membranes
  • control gene expression
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3
Q

Endocrine vs. exocrine

A

Endocrine - hormones secreted into the blood and blood carries the hormone to target tissue

Exocrine - hormones secreted into a duct (ex:salivary glands)

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4
Q

4 defining properties of hormones

A
  1. Secreted by cells/group of cells
  2. Secreted into the blood
  3. Transported by the blood to a distant target
  4. Act at very low concentrations
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5
Q

Phermones

A

Secreted and act on other individuals

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6
Q

3 categories of hormones

A

Peptides, proteins and glycoproteins

Steroids

Amines (based on tyrosine and tryptophan)

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7
Q

Where are peptide hormones made?

A

Peptide hormones are encoded for in the genome and translated. They are stored in vesicles until needed.

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8
Q

Where are steroid hormones made?

A

Produced in the smooth ER and made on demand from cholesterol

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9
Q

Example of a hormone that controls the transports of ions across the membrane

A

ADH

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10
Q

Example of a hormone that controls gene expression

A

Aldosterone

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11
Q

Where do endocrine glands secrete into?

A

Blood (global)

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12
Q

Where do exocrine glands secrete into?

A

Duct (local)

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13
Q

What is a molecule possesses SOME but not ALL of defining characteristics of hormones?

A

Classified as something similar but different: cytokine, growth factor, etc

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14
Q

Ectohormones

A

Another term for pheromone; ecto means “external”

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15
Q

Where / how are amine hormones made?

A

These include catecholamines and thyroid hormones

Made in advance and stored in vesicles (like peptide hormones)

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16
Q

Steps for secreting a peptide hormone

A
  1. mRNA on RER ribosome creates preprohormone
  2. Signal sequence of amino acids moves preprohormone into RER lumen
  3. Enzymes in ER chop off signal sequence, making prohormone
  4. Prohormone passes from ER in vesicle to Golgi
  5. Vesicles containing enzymes and pro hormones bud off golgi: enzymes inside continue to alter pro hormone into one or more active peptides plus peptide fragments
  6. Vesicle release contents by exocytosis into extracellular space
  7. Hormone is in circulation!!
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17
Q

Preprohormone

A

Peptide chain that will ultimately become a pro hormone and then a hormone; contains amino acid signaling sequence which directs it into the ER lumen

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18
Q

Prohormone

A

Inactive version of a hormone which passes through ER / Golgi: once altered by enzymes, becomes hormone

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19
Q

Signaling Sequence of Preprohormone

A

mRNA signal sequence indicates that this peptide needs to be translated at the RER; amino acid signal sequence indicates that peptide should continue into RER lumen

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20
Q

Proteolytic Cleavage

A

What peptides undergo to become active hormone (enzymatic chopping off of unnecessary bits)

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21
Q

From Proinsulin to Insulin

A
  1. Peptide chain creates disulfide bonds between two terminal strands of peptide sequence for insulin
  2. The middle part is chopped off to become a C-peptide, aka a peptide fragment
  3. And you’re left with working insulin!
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22
Q

What is our CLASSIC Model for the difference between STEROID and PEPTIDE hormones? (And is this classic model completely correct?)

A

STEROID HORMONES - diffuse through lipid bilayer to cytosolic or nucleoplasmic receptor, altering transcription / translation ; SLOW RESPONSE

PEPTIDE HORMONES - bind to cell surface receptor, allowing influx of ions / second messenger system / phosphorylation cascade ; FAST RESPONSE

Not completely correct! Hydrophilic hormones can alter transcription and steroid hormones can have immediate effects.

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23
Q

Receptors used by Peptide Proteins (and examples)

A

GPCR – ex., glucagon, ADH

Tyrosine Kinase – ex., insulin

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24
Q

How long should we wait if a signaling hormone binds to a cytoplasmic / nuclear receptor before we see effects?

A

About 90 minutes, the length of the central dogma

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25
Q

WHERE are steroid hormones made?

A

ALWAYS the Smooth ER, and primarily in either…

  1. Adrenal Cortex
  2. Gonads

Synthesized from cholesterol!

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26
Q

EXAMPLES of steroid hormones

A

Estradiol (ovary)
Estrone
Cortisol
Aldosterone

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27
Q

DHEA leas to the production of what intermediate products and hormones?

A

DHEA to Androstenedione to estrone to estradiol
DHEA to testosterone which can become Dihydrotestosterone or Estradiol

Enzymes involves: Aromatase

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28
Q

What does progesterone lead to?

A

Corticosterone, which becomes aldosterone

Enzyme: 21-hydroxylase

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29
Q

What three things is cholesterol used for?

A
  1. Steroid hormones
  2. Phospholipid Bilayer
  3. Bile salts!
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30
Q

Do you need to eat fat to get cholesterol?

A

No, your body can synthesize from acetyl groups and paste into long fatty acids

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31
Q

Famous Catecholamines

A

Dopamine, Norepinephrine, epinephrine

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32
Q

Famous Thyroid Hormones

A

Thyroxidine (T4), Triiodothyronine (T3)

33
Q

How are thyroid hormones different from catecholamines CHEMICALLY? How are they the same CHEMICALLY?

A

BOTH use tyrosine as a precursor

Catecholamines include ONE TYROSINE and ONE AMINE group

Thyroid hormones are made from TWO TYROSINES and several IODINE atoms

34
Q

Other than binding to a target, what can happen to a hormone once in circulation in the blood?

A

PATH A: Excreted in urine or feces
PATH B: Inactivated by metabolism
PATH C: ACTIVATED by metabolism!

Only Path C leads to binding

35
Q

Parathyroid Hormone (PTH)

A

Secreted in response to low plasma calcium levels in order to increase plasma calcium

36
Q

Simple Endocrine Reflex Pathway of Parathyroid Hormone

A
  1. Low plasma calcium
  2. Parathyroid cell secretes parathyroid hormone into blood
  3. Reaches bone and kidney
  4. Up bone resorption / breakdown, up kidney reabsorption of calcium, produce calcitriol to up intestinal absorption of calcium
  5. Final result: INCREASE IN PLASMA CALCIUM

NEGATIVE FEEDBACK LOOP: High concentrations of plasma calcium SHUT OFF the pathway.

37
Q

Bone Resorption

A

Breakdown of bone to liberate calcium in the blood

38
Q

Reflex Pathway

A

Does not have to go to the brain in CNS; only goes to the SPINE, much faster response

39
Q

Simple Endocrine Pathway for Insulin

A
  1. Three signals can arrive to tell the pancreas to increase glucose:
    A. Increase blood glucose
    B. Stretch receptor in digestive tract talk to CNS, and efferent neurons signal to pancreas
    C. Glucose in lumen uptakes by small cells to produce GLP-1, which signals to pancreases
  2. Pancreas produces insulin
  3. Released into blood to target tissues
  4. Glucose is taken up by cells
  5. Blood glucose decreases, SHUTS OFF PATHWAY A
40
Q

GLP-1

A

Glucagon-peptide 1, secreted by endocrine cells of small intestine in response to glucose in the lumen

Signals to pancreas to secrete insulin

41
Q

How the NS interfaces with the endocrine system

A

Central Nervous System talks to

  1. Autonomic NS
  2. Hypothalamus
42
Q

How autonomic NS interfaces with endocrine system

A

ONE NEURON RELAY from CNS to adrenal medulla, secreting epinephrine (only excitatory!! ++++)

TWO NEURON RELAY from CNS to endocrine gland cell, to secrete a hormone (can send excitatory or inhibitory signal, aka +++ or —)

43
Q

How hypothalamus interfaces with endocrine system

A

TWO STEP: RELEASING HORMONE can signal to ANTERIOR PITUITARY, which then secretes hormones (+++ or —)

ONE STEP: Neuronal axons in the POSTERIOR PITUITARY can secrete hormones directly

44
Q

Pituitary Gland

A

Two fused glands that are completely different! Anterior Pituitary + Posterior Pituitary

45
Q

Anterior Pituitary

A

A true endocrine gland: receives hormone signal from hypothalamus, then secretes its own hormones

46
Q

Posterior Pituitary

A

Extension of the neural tissue of the brain: the hypothalamus extends cell bodies into this area and secretes hormones directly

47
Q

Infundibulum

A

The stalk that connects the pituitary to the brain

48
Q

Hypothalamus + Posterior Pituitary (Purpose and Action)

A

The frontier between the NS and endocrine system

Secretes NEUROHORMONES: specifically oxytocin and vasopressin/ADH (very chemically similar!)

49
Q

Purpose of oxytocin

A

Social, sexual, and maternal behaviors

Milk release, uterine contractions during delivery of baby, cuddling????? autism????

50
Q

Purpose of vasopressin/ADH

A

Retain water

51
Q

Neurohormone

A

Hormones synthesized in and released by neurons: ONLY OCCURS IN POSTERIOR PITUITARY!

(check that – is it only in the posterior pituitary? ask Wien)

52
Q

Tropic/Trophic Hormone

A

A hormone that controls the release of another hormone

53
Q

How hormones are secreted from anterior pituitary

A
  1. Neurons from hypothalamus secrete RELEASING hormones
  2. Portal vessels carry to anterior pituitary, where they act on endocrine cells
  3. Endocrine cells release PEPTIDE HORMONES (mostly TROPIC HORMONES) into second set of capillaries
54
Q

Portal vessels

A

Vessels that carry releasing hormones from hypothalamus to ANTERIOR pituitary, where they trigger the release of other hormones (mostly tropic hormones)

55
Q

How many hormones does the anterior pituitary secrete??

A

Just six!

56
Q

What are the hormones secreted by the anterior pituitary and where does each go?

A
  1. Prolactin (mammary glands)
  2. GH (musculoskeletal system)
  3. TSH (thyroid gland)
  4. ACTH (adrenal cortex)
    5 & 6. LH and FSH (ovary, testis: GONADS)
57
Q

Difference between RELEASING and TROPIC hormones?

A

RELEASING hormones is the term we will use for hypothalamic hormones

TROPIC is the term we use for anterior pituitary hormones

58
Q

The ONE anterior pituitary hormone that is NOT a tropic hormone

A

Prolactin

Goes directly to breast, does not release a different hormone!

59
Q

What are the ONLY two hormones that go to both MANY tissues AND germ cells?

A

Androgens and estrogens, progesterone

60
Q

Definition of complex endocrine pathway

A

Involves series of hormones that lead to release of hormones and finally a response

Hormones of the pathways serve as negative feedback signals

61
Q

Example of complex endocrine pathway

A
  1. Stimulus talks to hypothalamus
  2. Release of releasing hormone to anterior pituitary
  3. Anterior pituitary releases tropic hormone
    SHORT LOOP NEG FEEDBACK: Tropic hormone inhibits hypothalamus!
  4. Tropic hormone talks to endocrine gland, which releases its own hormone
    LONG LOOP NEG FEEDBACK: Endocrine gland hormone inhibits BOTH anterior pituitary AND hypothalamus
  5. Hormone talks to target issue, leading to response
62
Q

Short Loop Negative Feedback

A

When a tropic hormone inhibits the release of a releasing hormone (only one step apart)

63
Q

Long Loop Negative Feedback

A

When hormone from endocrine gland prevents release of 1. releasing hormone and 2. tropic hormone

64
Q

What is the purpose of having both short- and long-loop negative feedback?

A

To finetune regulation

65
Q

Cortisol Secretion Step-by-step

A
  1. Hypothalamus secretes CRH (releasing hormone)
  2. Anterior pituitary secretes ACTH (tropic hormone)
  3. Adrenal cortex secretes cortisol
    LONG LOOP NEG FEEDBACK: Cortisol inhibits CRH and ACTH
  4. Cortisol talks to target tissue, response
66
Q

Three types of endocrine disorders

A
  1. Hyposecretion
  2. Hypersecretion
  3. Hypo or hyper responsiveness
67
Q

Hyposecretion

A

Undersecretion of hormone

Common, easily treated with exogenous hormones

68
Q

Hypersecretion

A

Oversecretion of hormone

Usually caused by hormone-secreting tumor, more difficult to treat

69
Q

Hypo or hyper responsiveness

A

Receptor binding / activation issue (enough signal, but the signal isn’t being received)

Signaling pathway broken (receptor is fine, but signal still cannot be received)

70
Q

Complications of exogenous hormone treatment

A

Still have negative feedback pathway even though the ultimate gland is secreting no hormone!

So if adrenal cortex won’t secrete cortisol, giving it through a pill will result in DECREASE of CRH and ACTH

This is why you have to be weaned off exogenous hormone drugs : your body has down-regulated the entire supply chain

71
Q

Cortisol case study: Pathology in adrenal cortex indicated by…?

A

HIGH cortisol, LOW CRH / ACTH

Cortisol is high and therefore negative feedback loops working, but no longer requires the releasing / tropic hormones to signal

72
Q

Cortisol case study: Pathology in anterior pituitary indicated by…?

A

HIGH cortisol, HIGH ACTH, LOW CRH

CRH should signal to anterior pituitary, but does not require CRH signal to stimulate pathway

73
Q

Cortisol case study: Pathology in hypothalamus indicated by…?

A

HIGH cortisol, HIGH ACTH, HIGH CRH

CRH should be shut off by high cortisol! But if high cortisol and still high CTH, that is a problem

74
Q

Hyposecretion Disorder

A

You will have HIGH levels of hormone early in pathway, yet no hormone ultimately produced

75
Q

Synergistic Effect of Hormones

A

Glucagon alone will not lead to high blood glucose, nor will epinephrine alone

But glucagon + cortisol + epinephrine leads to VERY HIGH blood glucose levels

So stress + diabetes = problem!

76
Q

Thyroid Hormones

A

Made in advance and PRECURSOR is stored in secretory vesicles, released by modification and simple diffusion

Bound to carrier proteins, act like a steroid hormone because diffuse into cell for intra-cellular receptor, triggering transcription / translation

Triggers creation of new proteins

77
Q

Catecholamines

A

Made in advance and stored in vesicles, released via EXOCYTOSIS

Dissolved in blood plasma, bind to receptor on cell surface, activate second messenger systems

Triggers modification of existing proteins

78
Q

What do you need to decide dosage of a drug?

A

Half-life of drug / hormone in system

Intro Bio II Exam 3 (8 decks)

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