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Histology Pt. 2 > Unit 2 - Intro into Endocrine Physiology > Flashcards

Unit 2 - Intro into Endocrine Physiology Flashcards

1
Q

What is a hormone?

A

a signaling molecule released by a cell and conveyed by the blood stream by neural axons, or by local diffusion to cells in target tissues

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2
Q

What is a hormones chemical nature?

A

protein, peptide, catecholamine, steroid, or iodinated tyrosine derivative

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3
Q

What do hormones do at the target tissue?

A

regulates metabolic pathways, via second messengers, or regulates synthesis of enzymes and other proteins at the DNA level

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4
Q

What is the function of the endocrine system?

A

to regulate metabolism, fluid status, growth, sexual development, and reproduction

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5
Q

What other system does the endocrine system work with in order to maintain homeostasis?

A

the nervous system

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6
Q

What are the four types of hormonal action based on the route by which the signalling molecule reaches the target?

A

autocrine, paracrine, endocrine, and neurocrine

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7
Q

What is autocrine action?

A

the hormone acts on the cell which released it; it binds on the cell itself

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8
Q

What is paracrine action?

A

the hormone acts on adjacent cells without entering the blood stream

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9
Q

What is endocrine action?

A

before reaching target cells, hormone first enters the blood stream

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10
Q

What is neurocrine action?

A

it refers to the interaction between neurons and endocrine cells

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11
Q

What are the four categories of hormones?

A

Peptide, protein, and glycoprotein hormones, catecholamine hormones, thyroid hormones, steroid hormones

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12
Q

How are peptide, protein, and glycoprotein hormones synthesized?

A

DNA to messenger RNA to preprohormone to prohormone to hormone

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13
Q

How are peptide, protein, and glycoprotein hormones stored?

A

in secretory granules originating from the golgi apparatus

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14
Q

How are peptide, protein, and glycoprotein hormones secreted?

A

by exocytosis

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15
Q

How are catecholamine hormones synthesized?

A

from amino acid tyrosine

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16
Q

How are catecholamine hormones stored?

A

in secretory granules

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17
Q

How are catecholamine hormones released?

A

via exocytosis

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18
Q

How are thyroid hormones synthesized?

A

from tyrosine and iodine

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19
Q

How are thyroid hormones stored?

A

extracellularly in follicles of the thyroid gland as a component of a large protein molecule

20
Q

How are thyroid hormones secreted?

A

they have to be retrieved from the follicle and released from the storage protein

21
Q

What are steroid hormones synthesized from?

A

cholesterol

22
Q

How are steroid hormones stored?

A

they arent

23
Q

There is a possible 5th type of hormone, what is it?

A

lipokines

24
Q

What feedback system is the dominant mechanism of regulating hormone secretion?

A

negative feedback

25
Q

How does negative feedback work in regulating hormone secretion?

A

the condition requiring hormone action, such as deviation from homeostasis, is sensed, stimulating endocrine cells to secrete hormone to fix the abnormality. Once it is fixed, hormone secretion is ceased

26
Q

How would you characterize negative feedback?

A

common, stable, and critical for homeostasis

27
Q

How does positive feedback work in regulating hormone secretion?

A

once a hormone is first secreted , it promotes further secretion of hormone until some physiologic end point is achieved

28
Q

How would you characterize positive feedback?

A

rare, unstable, and used when a surge of hormone is required

29
Q

What happens to horomones after they are secreted into extracellular fluid?

A

they circulate either free or bound to other plasma constituents and are eventually taken up by cells or metabolically degraded and removed by urinary or biliary secretion

30
Q

What does half-life mean in regards to hormones?

A

it referes to the time in which the hormone loses 50% of its biological activity

31
Q

Describe the events that occur after hormones reach their target cells.

A

the hormone binds to a specific receptor in the target cell, this changes the enzyme activity or concentration which leads to the regulation of mutliple metabolic pathways and results in the physical change the hormone was set out to accomplish

32
Q

Which property of a cell determines whether it will be affected by a particular hormone?

A

the hormone concentration together with the number and sensitivity of involved receptors

33
Q

Where are lipophilic receptors normally found?

A

within the cell; cytoplasm or nucleus

34
Q

Where are lipophobic receptors normally found?

A

on the cell membrane

35
Q

What are first messengers?

A

extracellular signaling molecules that second messengers respond to

36
Q

What are second messengers?

A

intracellular signaling moleciles released by the cell in response to exposure to extracellular signaling molecules

37
Q

How are second messengers activated?

A

by enzymes

38
Q

What are the consequences of second messenger actions?

A

they alter the cells physiology

39
Q

What second messenger systems are most commonly activated by protein and catecholamine hormones?

A

cAMP or IP3/DG

40
Q

How do second messengers affect the physiology of target cells?

A

they activate protein kinases which phosphorylate other proteins leading to the eventual physiologic effect

41
Q

Why can relatively few molecules of hormones produce a large physiologic response?

A

intracellular signal amplification

42
Q

How does intracellular signal amplification work?

A

a signal ligand activates multiple G proteins, each G protein activates an inzyme that produces multiple molecules of the second messenger, the second messengers then activate other enzymes and each enzyme reactions on multiple molecules of the substrate

43
Q

What happens when a steroid binds to its receptor within a cell?

A

the shape of the receptor changes and forms a bond with a transcription regulating hormone

44
Q

The dimer formed when a steroid binds to a transcription regulating protein can have what result?

A

an increase or inhibition of transcroption and translation

45
Q

What are the products of steroid hormone action?

A

enzymes, structural proteins, receptor proteins, and transcriptional proteins

46
Q

What does the synergism of hormonal action mean?

A

that different types of hormones can work together

47
Q

What is an example of a process that uses synergism of hormonal action?

A

gluconeogenesis

Histology Pt. 2 (52 decks)

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