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ANBI 420 > Module 1 > Flashcards

Module 1 Flashcards

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1
Q

What are the basic components that make up the endocrine system?

3pts

A
  1. Endocrine gland/cell
  2. Hormone
  3. Target organ
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2
Q

What is an endocrine gland?

1pt

A

A ductless gland that secretes hormones directly into the blood/lymph

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3
Q

What is a hormone?

1pt

A

Physiological organic substance produced by certain specialized cells and released into circulating blood or lymph for transport to target tissues in distant organs to exert specific actions

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4
Q

classical hormones are signal molecules that…

4pts

A
  1. are synthesized by endocrine cells
  2. are secreted into the circulation
  3. interact with proteins called receptors
  4. have specific effects on target cells
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5
Q

How are hormones classified?

3pts

A
  • Type of signalling
  • Chemical structure
  • Solubility
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6
Q

What are the ways cells signal with hormones?

5pts

A
  • Endocrine
  • Paracrine
  • Autocrine
  • Neuroendocrine/Neurocrine
  • Intracrine
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7
Q

What is endocrine signalling?

1pt

A

When hormones enter the bloodstream/lymph and bind to hormone receptors in target cells in
distant organs

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8
Q

What is an example of endocrine signalling?

1pt

A

Beta cells in the islets of Langerhans in the pancreas produce and release insulin into the blood where it travels to many tissues, including the liver signalling it to store glucose in the form of glycogen

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9
Q

What is paracrine signalling?

1pt

A

When hormones bind to cells near the cell that released them (same organ or tissue). It is often degraded quickly or taken up rapidly

Does not go into lymph or blood

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10
Q

What is an example of paracrine signalling?

1pt

A

Testosterone secreted from the leydig cells in testes acts as a paracrine agent to stimulate spermatogenesis in the adjacent seminiferous tubules

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11
Q

What is autocrine signalling?

1pt

A

When a hormone produces a biological effect on the same cell that has released it

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12
Q

What is an example of autocrine signalling?

1pt

A

The lining of mammalian endometrium responds to oxytocin in an autocrine/paracrine manner to cause production of prostaglandins (cause uterine contractions)

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13
Q

What is intracrine signalling?

1pt

A

When a hormone is synthesized and acts intracellularly (in the same cell)

Does not actually leave the cell

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14
Q

What is an example of intracrine signalling?

1pt

A

Precursor sex steroid hormones are synthesized and then are converted by enzymes to active androgens/estrogens which bind to receptors within the same cell

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15
Q

What is a neurohormone?

1pt

A

A neurohormone is a hormone produced by a nerve cell

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16
Q

What is neuroendocrine signalling?

1pt

A

A hormone (neurohormone) released by a nerve is blood borne

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17
Q

What is neurocrine signalling?

1pt

A

A neuron contacts its target cell by axonal extensions and releases hormones (neurohormone) into the synaptic cleft

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18
Q

What is exocrine signalling? Give an example.

2pts

A

Pheromone that is released externally to initiate response in or communicate with another organism
Example: Fish use to assist social behaviour, such as schooling, identification of conspecifics and potential mates, etc.

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19
Q

What are pheromones used for?

3pts

A
  • Within species for identification
  • Reproductive attractants: bombykol (female moths), steroid breakdown products (fish)
  • Repel predators (skunk musk)
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20
Q

What are examples of human pheromones?

3pts

A
  • Effects on the menstrual cycle (primer effects–cause a shift in the endocrine system of the receiving animal)
  • Olfactory recognition of newborn by its mother (signaler effect—relays information)
  • Individuals may exude different odors based on mood (modulator effects, e.g., androstadienone and estratetraenol)

Human pheromones **cannot ** cause someone to be attracted to you

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21
Q

What are the structural groups that hormones are catagorized into?

4pts

A
  • Peptides and proteins*
  • Amino acid derivatives (amines)*
  • Steroids (derived from cholesterol)
  • Eicosanoids (fatty acid Derivatives)

*Amino-acid based hormones

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22
Q

What are peptide and protein hormones?

3pts

Study These Flashcards
A
  • Constitute majority of hormones
  • Range from 3 to 200 amino acids
  • Synthesized as preprohormones and undergo post-translational processing
23
Q

How are preprohormones processed and released from the cell?

6pts

Study These Flashcards
A
  1. Messenger RNA on the ribosomes binds amino acids into a peptide chain called a preprohormone. The chain is directed into the ER lumen by a signal sequence of amino acids.
  2. Enzymes in the ER chop off the signal sequence, creating an inactive prohormone.
  3. The prohormone passes from the ER through the Golgi complex.
  4. Secretory vesicles containing enzymes and prohormone bud off the Golgi. The enzymes chop the prohormone into one or more active peptides plus additional peptide fragments.
  5. The secretory vesicle releases its contents by exocytosis into the extracellular space.
  6. The hormone moves into the circulation for transport to its target.
24
Q

What are the pathways that peptide/protein hormones can be secreted? Explain them.

4pts

Study These Flashcards
A
  1. Constitutive secretion
    * Hormones are relased directly
  2. Regulated secretion
    * Hormones are stored in vesicles and released as needed
25
What are amine hormones?
Derived from amino acids, normally tyrosine - but also tryptophan (precursor to serotonin and melatonin) and glutamic acid (converted to histamine)
26
What are some examples of amine hormones? | 4pts
* Norepinephrine * Epinephrine * Dopamine * Thyroid hormones
27
What are thyroid hormones and what are they produced by? | 5pts
* Thyroid hormones are basically a "double" tyrosine with the critical incorporation of 3 or 4 iodine atoms. * Produced by the thyroid gland 1. Modification of a tyrosine residue contained in thyroglobulin 2. Post-translationally modified to bind iodine 3. Proteolytically cleaved and released as T4 and T3. | Amine hormone
28
How is thyroid hormone transported? | 1pt
T3 and T4 then bind to thyroxin binding globulin (TBG) to be transported in the blood
29
what are catecholamines? Give examples. | 2pts
* Catecholamines are both neurohormones and neurotransmitters. * Epinephrine and norepinephrine | Amine hormone
30
How are catecholamines produced and secreted? | 2pts
* Epinephrine and norepinephrine are produced by the adrenal medulla (both are water soluble) * Secreted like peptide hormones (release in vesicles via exocytosis)
31
What are characteristics of steroid hormones? | 4pts
* Cholesterol-derived * Lipophilic and easily crosses membranes * Bind carrier proteins in blood * Longer half-life * Cytoplasmic or nuclear receptors * Genomic effect to activate or repress genes for protein synthesis * Slower acting * But some can ALSO bind to cell membrane receptors * Nongenomic responses
32
What are some examples of steroid hormones? | 5pt
* Glucocorticoids * Mineralocorticoids * Androgens * Estrogens * Progestogen
33
What are eicosanoids and where are they derived from? | 2pts
* Modified 20-carbon (eikosi, twenty) fatty acids with complete/partial carbon ring and 2 long carbon “tails” * All derived from arachidonic acid
34
What physiological processes are eicosanoids involved in? | 3pts
* Prostaglandins (constriction/dilation smooth muscle cells) à asthma and anaphylaxis * Leukotrines (inflammation compounds) * NSAIDs and COX2 inhibitors
35
Why is it important to know hormone structure? | 5pts
* Determines how molecules are transported in blood (hydrophilic or hydrophobic?) * Influences half-life of the hormone * Determines how molecules exit endocrine cells and how interact with target cells (hydrophilic or hydrophobic?) * Specificity for receptors (therefore, function) * Conservation during evolution of vertebrates
36
Disease results when hormone concentrations are... | 1pt
too high or too low | precise control over circulating concentrations of hormones is crucial
37
Concentration of hormone as seen by target cells is determined by... | 3pts
1. Rate of production 2. Rate of delivery 3. Rate of degradation and elimination
38
Waht is rate of production/secretion mediated by? | 1pt
Positive and negative feedback circuits
39
What are the ways hormone production is stimulated? Explain each way. | 6pts
* Humoral stimulus * Hormone release caused by altered levels of certain critical ions or nutrients * Neural stimulus * Hormone release caused by neural input * Hormonal stimulus * Hormone release caused by another hormone (a tropic hormone)
40
What is an example of a negative feedback loop? | 1pt
Hypothalamus → GnRH –”+” → Anterior pituitary → FSH, LH –”+” → Ovary → Estradiol –”-” → Anterior pituitary
41
What is an example of a positive feedback loop? | 1pt
Hypothalamus → GnRH –”+” → Anterior pituitary → FSH, LH –”+” → Ovary → Estradiol –”+” → Anterior pituitary | A spike in LH allows ovulation to occur
42
What is an example that shows rate of delivery of a hormone? | 1pt
Blood flow to a target organ or group of target cells. High blood flow delivers more hormone than low blood flow
43
How do hormones circulate in the blood? | 2pts
* Circulate freely (water soluble hormones) * Circulate bound to large proteins (lipid soluble hormones)
44
What are examples of transport proteins? | 5pts
* Bind small ligands, general transport molecules * Albumin * Transthyretin * Specific transport proteins * Corticosteroid binding globulin : bind small ligands, general transport molecules * (CBG)Thyroxine binding globulin (TBG) * Sex hormone binding globulin (SHBG)
45
What percentage of hormones are bound? | 1pt
90%
46
How are hormones degraded or metabolized? | 4pts
* Some are metabolized at their target cells * Some are metabolized by enzymes in circulation * Many are metabolized by enzymes in the liver or kidneys * Most hormones are excreted via the kidneys (some via liver --> Bile)
47
What is half-life? | 1pt
The time during which the concentration of hormone decreases to 50% of its initial volume
48
What does shutting off the secretion of a hormone that has a very short half-life do? | 1pt
It causes the circulating hormone concentration to plummet
49
What does shutting off secretion of a hormone that has a long half-life do? | 1pt
It would take some time to notice that it has been shut off.
50
What is the metabolic clearance rate (MCR) and how do you calculate it? | 2pts
* The removal of hormones from circulation, the volume of plasma cleared of the hormone per unit time MCR= (mg/min removed) / (mg/ml plasma) = mL plasma cleared/ min
51
What is the hormone metabolic fate? | 3pts
* Metabolic degradation --> mainly in the liver through enzymatic processes. * Excretion of hormone metabolites occurs through the bile or urine. * In addition, the target cell may internalize the hormone and degrade it.
52
Why is the role of the kidney in eliminating hormone and its degradation products from the body important? | 1pt
Gets rid of excess hormones
53
What are the mechanisms of hormone action | 5pts
* Alter plasma membrane permeability of membrane potential by opening or closing ion channels * Stimulate synthesis of proteins or regulatory molecules * Activate or deactivate enzyme systems * Induce secretory activity * Stimulate mitosis

ANBI 420 (9 decks)

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