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Systems Physiology > Introduction to Endocrinology > Flashcards

Introduction to Endocrinology Flashcards

1
Q

*Name the major endocrine glands and their hormonal product or products

A

Major endocrine glands:
1. Hypothalamus- secrete Thyrotropin releasing hormone(TRH) , GnRH (gonadotropin releasing hormone), CRH (corticotropin releasing hormone), Somatostatin, Dopamine, GHRH (growth hormone releasing hormone),
2. Posterior Pituitary- releases Oxytocin, ADH (vasopressin), (arginine, vasopressin)
3. Anterior Pituitary- FLATPIG. This gland releases:
TSH (thyroid stimulating hormone), LH (luteinizing hormone), FSH (follicle stimulating hormone), Prolactin, ACTH (Adrenocorticotropic hormone), Growth Hormone (GH),
4. Thyroid gland- releases T3, T4, Calcitonin
5. Parathyroid produces PTH (parathyroid hormone)
6. Adrenal glands: (medulla and cortex secrete different hormones).
-Adrenal cortex secrete Mineralocorticoid (aldosterone), Testosterone, estrogen, progesterone, cortisol
-Adrenal medulla secretes epinephrine, and Norepinephrine
7. Pancreas secretes: Insulin, glucagon and somatostatin
8. Ovaries secrete progesterone, estradiol, inhibin
9. Testes secrete testosterone (androgen), inhibin (inhibits FSH)
10. Liver - secretes IGF-1.

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2
Q

*Explain the chemical nature and the characteristics of protein/peptide hormones, catecholamine hormones, steroid hormones, and iodothyronines (thyroid hormones). Include such characteristics as site of regulation (synthesis or secretion), circulating form of hormone, subcellular localization of hormone receptor and metabolic clearance.

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3
Q

*Integrate the intracellular steps associated with a hormone response in a target cell

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4
Q

*Define a releasing hormone and a tropic hormone

A

Releasing hormone- peptide hormone that are produced in hypothalamus and directly stimulate tissues (GnRH, CRH, GHRH)
tropic hormone- a hormone that targets other endocrine glands to release hormones. Most tropic hormones are from anterior pituitary (stimulate FLATPIG)

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5
Q

*Map out a simple endocrine negative feedback loop and one involving the hypothalamus, anterior pituitary and peripheral endocrine gland, and list the major endocrine glands under each type of feedback loop

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6
Q

*Integrate the concept of peripheral conversion with the function/action of a secreted hormone

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7
Q

What is Endocrinology? What are the roles of Hormones?

A

Endocrinology- the study of hormones
Hormones are chemical signals (ligands)
-they are used for cell-to-cell communication
-Secretion is regulated
-*Hormones bind to receptors on/in target cells
Hormone must bind to a specific receptor (they also need a signal to be released.

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8
Q

What is the result of dysregulation of hormones?

What are examples of this?

A

The dysregulation of hormones lead to disease
Disease can arise from hyposecretion (too little Thyroid hormone), Hypersecretion (too much Thryoid hormone) and or nonfunctional receptors(hormone binds receptor an receptor does NOT work).
Other diseases due to hormone imbalances:
-Type 1 diabetes- immune disruption, pancreas does not produce insulin (immune system destroys beta cells)
Type 2 diabetes- body cells resist effects of insulin (leading to high glucose levels in blood)
Cushing’s Disease- body produces too much cortisol

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9
Q

Explain how cells communicate with one another. Also describe the types of cellular communication

A

Cells communicate with one another:
-through signal –> Receptor–> Response
types of cellular communication
1. Autocrine signaling- A signal cell releases signal that binds to receptor on the same cell (itself)
2. Paracrine signaling- signaling cell releases signal and the signal reaches a target cell nearby (induce change in nearby cells)
3. Endocrine/Hormonal signal- signaling cell releases hormone which travels through blood to a target cell at a distant site
ex: erythropoietin (EPO) binds to EPO receptor on target cell
4. Neural signaling (neuroendocrine)- action potential down an axon, will cause vesicles to fuse with presynaptic membrane and release neurotransmitters into synaptic cleft. Neuroendocrine cell can release hormone that is picked up when traveling through blood.
any cell to cell communication involves signal and receptor.
ex: erythropoietin (EPO) binds to EPO receptor on target cell

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10
Q

Explain how different endocrine glands communicate. Provide an example.

A

In endocrine communication, multiple endocrine glands may be involved.
Ex: Thyroid Hormone
1. Hypothalamus secretes Thyrotropin releasing hormone (TRH).
2. TRH travels to Anterior Pituitary gland to stimulate Thyroid Stimulating Hormone (TSH) release
4. TSH travel through the blood to reach Thyroid gland (TSH bind to TSH receptor on thyroid).
5. The thyroid gland will then release Triiodothyroine (T3) and Thyroxine (T4).

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11
Q

Explain the key biology principle of form fits function and how it relates to hormones.

A

Key biological principle: form fits function

hormones have different forms (structures) which leads to different characteristics and functions

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12
Q

What are the different classifications of hormones? provide examples of each.

A

Different classifications of hormones:

  1. peptide/protein hormones: majority of hormones in body (ex: Insulin, GH, ADH)
  2. Catecholamines (amino acid derived); all come from modified version of a.a Tyrosine (ex: Epinephrine, NE, Dopamine)
  3. Steroid Hormones (ex: estrogen, tesosterone ,cortisol, Vitamin D, mineralocorticoids)
  4. Iodothyronines or thyroid hormones (amino acid derived: ex: T3 and T4; more abundant) modify a.a tyrosine and add iodines.
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13
Q

How do you determine hormone behavior?

A

Hormone behavior depends on the CHEMICAL COMPOSITION.

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14
Q

Differentiate between the chemical characteristics of hydrophilic and hydrophobic. Also compare them to lipophilic and lipophobic. Which hormones have which of the characterisitics?

A

Chemical characteristics:
Hydrophilic- water loving (polar)
-hydrophobic- water hating (nonpolar)
Lipophilic( FAT loving)- hydrophobic, while lipophobic (fat hating) is hydrophilic.
Hormones:
1. Protein/peptide hormones and catecholamines are HYDROPHILIC
2. Steroids are HYDROPHOBIC
3. Iodothyronines are complicated (posses both hydrophilic and hydrophobic properties)

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15
Q

If blood is an aqueous solution (hydrophilic), how can hydrophobic steroid hormones travel through the blood?

A

Hydrophobic (non-polar) steroid hormones can travel through the blood with BINDING PROTEINS.

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16
Q

What are binding proteins? provide examples of each. What binds to steroids?

A

Binding proteins:
-SEX-hormone binding globulin (SHBG), thyroid binding globulin (TBG), and cortisol binding globulin (CBG) bind the cognate steroids with HIGH specificity.
-Albumin binds Non-Specifically to ALL steroids, but with LOW affinity.
Binding proteins increase the half-life of hormones- but these hormones are not metabolized by liver and kidney
-when a hormone binds to binding proteins, the liver and kidney cannot have access to it (stays in circulation longer)

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17
Q

Differentiate between free hormone and a bound hormone

A

Free hormone- ACTIVE

Bound hormone= Inactive (cannot enter cells)

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18
Q

Describe what substance depends on binding proteins. What is the measure for total hormone concentration?
What happens to total hormone concentration if binding protein concentration in blood increases?

A

Circulating hormone concentrations depend on binding proteins
-Total [hormone] = [free hormone] + [bound hormone]
-Bound hormone represents back-up supply that can be used when hormone secretion is low.
If binding protein concentration increases, total hormone concentration INCREASES.

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19
Q

Explain the production, processing and release of peptide/protein hormones.

A

Peptide/protein hormone processing:

  1. DNA will, undergo transcription (splice out introns, ligate exons)
  2. mature RNA will leave the nucleus, cytoplasm and go to ribosome to form signal sequence hormone and co-peptides
  3. signal sequence will direct MRNA to ribosome for translation, where mRNA will be translated to protein- form prepohormone and Nh2-signal hormone
  4. signal sequence hormone cleaved in ER, leave hormone in peptide hormone and co-peptides (prohormone)
  5. Then the hormone will leave ER and enter golgi apparatus and processing and packing will occur into vesicles.
  6. peptidases will cleave bond and form hormone and co-peptides and eventually a hormone.
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20
Q

Where are peptide/protein hormones stored? When are they released?

A

Peptide/protein hormones are stored in granules/vesicles until they are signaled to be released
Hormones must be SIGNALED to be released.

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21
Q

How are catecholamines (polar) synthesized?

A

Synthesis of Catecholamines (Polar):
- You start with amino acid (Tyrosine) and then use enzymes to convert to different catecholamines.
These catecholamines are made in the CYTOSOL and stored until signaled to be released.
Ex: you modify tyrosine to form DOPA which leads to forming Dopamine–> NE–> Epinephrine

22
Q

Describe what occurs in polar hormone signaling. How do polar hormones pass through membranes? What must occur in cascade?

A

Polar hormone signaling:
polar molecules (hydrophilic) CANNOT pass through the hydrophobic cell membrane.
-These hormones NEED to bind to a RECEPTOR embedded in cell membrane
-Hormone binding directly opens Ion channels (Ionotropic)
-Hormone binding stimulates secondary messenger cascades (metabotropic)
- Cellular responses occur FAST (milliseconds-minutes)
Hormone must bind to receptor to activate tyrosine domain, and phosphorylate protein for cellular response.

23
Q

Describe the process o synthesizing Steroid (non-polar ) hormones.

A

Biosynthesis of Steroid Hormones (Non-Polar)
Cholesterol is the common precursor for steroids
Different enzymes produce different steroid hormones
Endocrine cells synthesize specific enzymes, which determine which hormones are produced.
Examples:
Granulosa cells in ovary make aromatase, which can convert tesosterone into estradiol.

24
Q

Which steroid hormones have enzymes made in mitochondria vs smooth ER.

A

Progesterone, androgen, estrogen have enzymes that are made in Smooth ER.
Glucocorticoids and mineralocorticoids have enzymes that are made in MITOCHONDRIA

25
Q

Discuss the hormones that each steroid hormone make.

A 
Progestagen-makes progesterone
glucocorticoids- makes cortisol
Androgen- makes testosterone
Estrogen- makes estradiol
Mineralocorticoids- make Aldosterone
26
Q

Describe the compositions of a steroid hormone producing cell.

A

steroid hormone cell contains:
-numerous mitochondria, smooth ER and lipid droplets which are involved in steroid hormone synthesis
-Steroids are released IMMEDIATELY (they are NOT stored in cells)
Steroid lipid droplets contain cholesterol.
steroid hormones are regulated by enzymes (ex: aromatase is regulated to make estrogen).

27
Q

What is a colloid? Where is thyroglobulin made?

A

Colloid- place where thyroid hormones are made. thyroglobulin is made in the follicular cells.

28
Q

Describe the components of thyroid hormone synthesis.

A

Thyroid Hormone synthesis:

  • requires enzymes, iodine, thyroglobulin, and tyrosine
  • T3 and T4 are stored in cytoplasmic vesicles until stimulated by TSH (Polar-like)
  • Then T3 and T4 travel through the circulation bound to albumin and TBG (thryoid binding globulin; nonopolar like).
29
Q

Explain the steps of how thyroid hormone is made from tyrosine and iodine

A

Synthesis of thyroid hormone (from tyrosine + Iodine):

  1. Na+-I- symporter brings Iodine (I-) into the cell. The pendrin transporter moves I- into the colloid
  2. Follicular cell synthesizes enzymes and thryoglobulin for colloid
  3. Thyroid peroxidase adds iodine to tyrosine to make T3 and T4
  4. Thyroglobulin is taken back into cell in vesicles
  5. Intracellular enzymes separate T3 and T4 from the protein
  6. Free T3 and T4 enter the circulation.
30
Q

Wat combinations give you MIT(monoiodotyrosine), DIT (diodotyrosine) , T3, T4?

A

MIT: I- + tyrosine
DIT: I- + MIT
T3: MIT + DIT
T4: DIT + DIT

31
Q

Where are most steroid hormones made? Why are they not stored in the endocrine cell?

A

Most steroid hormones are made in the ADRENAL CORTEX or GONADS (ovaries and testes). Steroid hormones are NOT stored in the endocrine cell because of their LIPOPHILIC nature. They are made on demand and diffuse out of the endocrine cell.

32
Q

*Describe the factors of steroid and thyroid hormone signaling.

A

Steroid and thyroid hormones CAN pass through the cell membrane, so they bind to INTRACELLULAR receptors.
These receptors typically dimerize and then bind to DNA
Genes are up or down regulated
and Responses are SLOW (hours-days)

33
Q

Describe the characteristics of steroid hormones acting primarily on intracellular receptors.

A
  1. Most hydrophobic steroids are bound to plasma protein carriers. Only unbound hormones can diffuse into the target cell
    2 Steroid hormone receptors are in the cytoplasm or nucleus.
    2a. some steroid hormones also bind to membrane receptors that use Second messenger systems to create rapid cellular responses
    3 The receptor hormone complex binds to DNA and activates or represses one or more genes.
  2. Activated genes create new mRNA that moves back to the cytoplasm (transcription)
  3. Translation produces new proteins for cell processes.
34
Q

How does Norepinephrine affect vascular smooth muscle in the skin vs. skeletal muscle? How does this occur?

A

NE causes vasoconstriction of vascular smooth muscle in the SKIN
NE causes VASODILATION of vascular smooth muscle in the SKELETAL muscle. These opposing effects occur due to different receptors being activated and causing different effects.
The alphaadrenergic receptor- vasoconstriction in skin
The Beta-Adrenergic receptor- VASODILATION in skeletal muscle.

35
Q

Discuss the characteristics of PEPTIDE hormone in terms of where it is synthesized/stored, how it releases from parent cell, how it is transported in blood , half life, location of receptor, response to receptor ligand binding, general target response and examples.

A 
PEPTIDE Hormones:
synthesis: made in advance (ER)
Storage: stored in Secretory vesicles
Release from parent cell: EXOCYTOSIS
Transport in Blood- Dissolved in Plasma
Half-Life: SHORT
Location of receptor: Cell membrane
Response to Receptor-Ligand binding: Activation of second messenger systems: may activate genes
General Target Response: modification of existing proteins and induction of new protein synthesis
Examples: Insulin, parathyroid hormone
36
Q

Discuss the characteristics of STEROID hormones in terms of where it is synthesized/stored, how it releases from parent cell, how it is transported in blood , half life, location of receptor, response to receptor ligand binding, general target response and examples.

A

STEROID Hormones:
synthesis: Synthesized on DEMAND from precursors
Release from parent cell: SIMPLE DIFFUSION
Transport in Blood: bound to CARRIER proteins
Half-Life: LONG
Location of receptor: Cytoplasm or nucleus: some have membrane receptors also
Response to Receptor-Ligand binding: Activation of genes for TRANSCRIPTION and TRANSLATION; may have non-genomic actions
General Target Response: induction of new protein synthesis
Examples: Estrogen, androgens, cortisol

37
Q

Discuss the characteristics of CATECHOLAMINE (Amine hormones) in terms of where it is synthesized/stored, how it releases from parent cell, how it is transported in blood , half life, location of receptor, response to receptor ligand binding, general target response and examples.

A

CATECHOLAMINE (Amine Hormones)
synthesis: Made in Advance (adrenal glands)
Storage: stored in secretory vesicles
Release from parent cell; EXOCYTOSIS
Transport in Blood: Dissolved in Plasma
Half-Life: SHORT
Location of receptor: Cell membrane
Response to Receptor-Ligand binding: Activation of second messenger systems
General Target Response: Modification of existing proteins
Examples: Epinephrine, norepinephrine, dopamine

38
Q

Discuss the characteristics of THYROID hormones (Amine Hormones) in terms of where it is synthesized/stored, how it releases from parent cell, how it is transported in blood , half life, location of receptor, response to receptor ligand binding, general target response and examples.

A

THYROID Hormones (Amine Hormones)
synthesis: Made in Advance (thyroid gland) : Precusor stored in secretory vesicles
Release from parent cell: TRANSPORT protein
Transport in Blood: BOUND to CARRIER protein
Half-Life: LONG
Location of receptor: NUCLEUS
Response to Receptor-Ligand binding: Activation of genes for TRANSCRIPTION and TRANSLATION
General Target Response: Induction of new protein synthesis
Examples: Thyroxine (T4)

39
Q

What hormones do Adrenal glands secrete?

A

Adrenal glands: made up cortex and medulla
Adrenal cortex: secrete mineralocorticoid (aldosterone), testosterone, estrogen, progesterone, cortisol

Adrenal Medulla: secrete epinephrine, norepinephrine,

40
Q

What hormones do pancreas secrete?

A

Pancreas secretes Insulin, Glucagon and Somatostatin

41
Q

What hormones do ovaries and testes secrete?

A

Ovaries secrete progesterone, estradiol and inhibin

Testes secrete testosterone, or androgens, inhibin (inhibits FSH)

42
Q

What hormones does liver secrete?

A

Liver secretes IGF-1 (insulin-Like Growth Factor 1), and angiotensinogen.

43
Q

What process is homeostasis maintained by?

A

Homeostasis is maintained by NEGATIVE FEEDBACK.

44
Q

What is Negative Feedback?

A

Negative Feedback: The end response counteracts the initial stimulus.
When too much of a hormone or end product is made, it will inhibit further secretion of that hormone or formation of product (to lessen the product) and maintain equilibrium.

45
Q

Explain the endocrine axis-driven negative feedback loop.

A

Endocrine axis-negative feedback:
when blood concentrations of thyroid hormones or any hormone increase above a certain threshold, TRH-secreting neurons in hypothalamus are Inhibited and stop secreting TRH.

46
Q

Explain how thyroid hormone is made starting from hypothalamus all the way to blood.

A

In hypothalamus, TRH (thyroid releasing hormone) is made and will stimulate the anterior pituitary to make TSH (thyroid stimulating hormone). TSH will then bind to receptor on Thyroid gland and form T3 and T4 which will enter blood.

47
Q

What would happen if TRH release is stopped?

A

If TRH release stopped, TSH release from anterior pituitary would be STOPPED

48
Q

What would happen if too much TSH was released?

A

If too much TSH is released, then you will have a lot of T3, T4

49
Q

What happens if TOO much T3 or T4 were released?

A

if too much T3, T4 were released, NEGATIVE Feedback would occur, which would inhibit TRH from hypothalamus. If TRH is inhibited, it would inhibit TSH from posterior pituitary. Due to a low TSH being secreted, you would have low levels of T3 and T4.

50
Q

What is the purpose of peripheral hormonal conversions? Provide examples.

A

Peripheral Hormonal Conversions:
Less active hormone is secreted, then converted by enzymes to a more ACTIVE form in tissues
Example: convert less active from T4 to more active from T3.
another example:
convert Vitamin D3 to 1, 25 (OH)2 D3
and convert angiotensinogen to Angiotensin II.

51
Q

What is the purpose of ACE-Inhibitors?

A

ACE inhibitors prevent ACE (angtiotensin-converting enzyme) from producing angiotensin II.
Angiotensin II -narrows blood vessels.
Hence ACE inhibitors help relax blood vessels and and lower blood pressure (useful for people with high blood pressure)

Systems Physiology (19 decks)

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