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Clinical Chemistry > L.16 Intro to Endocrinology > Flashcards

L.16 Intro to Endocrinology Flashcards

1
Q
A
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2
Q

What is the endocrine system?

A

A network of glands that produce and release hormones to regulate various bodily functions

Includes processes such as metabolism, growth, reproduction, and mood

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3
Q

What are hormones?

A

Chemical messengers that travel through the bloodstream to target organs and tissues

Influence various bodily processes

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4
Q

How do exocrine glands differ from endocrine glands?

A

Exocrine glands secrete substances through ducts to the external environment or into body cavities

Examples: sweat glands, salivary glands

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5
Q

What do endocrine glands do?

A

Release hormones directly into the bloodstream

Target organs can be far from the gland itself

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6
Q

What are the characteristics of endocrine glands?

A
  • Do not have a duct system
  • Secrete hormones directly into the bloodstream
  • Target organs are often located far from the gland
  • Typically produce proteins or steroids
  • Secretory cells are often arranged in clusters or cords
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7
Q

What type of blood supply do endocrine glands typically have?

A

A rich blood supply

This allows for easy diffusion of hormones into the bloodstream

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8
Q

What are trabecular endocrine glands?

A

Gland cells arranged in cords or trabeculae, with a rich blood supply

Example: adrenal cortex

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9
Q

What are follicular endocrine glands?

A

Gland cells arranged in spherical follicles with a central lumen

Example: thyroid gland

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10
Q

What are disseminated endocrine glands?

A

Gland cells scattered throughout the tissue with no distinct organization

Example: pancreas

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11
Q

What are the three classes of hormones based on their chemical structure?

A
  1. Lipid-soluble hormones
  2. Peptide hormones
  3. Amino acid-derived hormones

These classes are distinguished by their chemical structure and behavior in the body.

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12
Q

What are lipid-soluble hormones derived from?

A

Cholesterol

Examples include steroid hormones like cortisol, testosterone, and estrogen.

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13
Q

What is a characteristic of steroid hormones?

A

They can pass through cell membranes and bind to intracellular receptors

Steroid hormones are usually either alcoholic (hydroxyl) or carbonyl (ketone) groups.

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14
Q

What do the names of steroid hormones typically end with?

A

-one (alcohol) or -ol (ketone)

Examples include testosterone and estradiol.

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15
Q

How are steroid hormones transported in the blood?

A

Bound to plasma proteins

They are insoluble in water and require transport proteins.

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16
Q

What is the half-life of cortisol?

A

60-90 minutes

This is longer compared to epinephrine, which has a half-life of approximately 1 minute.

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17
Q

What are peptide hormones made of?

A

Chains of amino acids

Examples include insulin, glucagon, and ADH.

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18
Q

How do peptide hormones interact with target cells?

A

They bind to receptors on the surface of target cells

This triggers a cascade of intracellular events.

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19
Q

What characterizes amino acid-derived hormones?

A

Derived from single amino acids

Examples include thyroid hormones and catecholamines.

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20
Q

What do the names of amino acid-derived hormones typically end with?

A

-ine

Examples include epinephrine, norepinephrine, and thyroxine.

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21
Q

What is the synergistic effect of hormones?

A

When two hormones work together to produce a greater effect than either hormone alone

It can be additive or complementary.

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22
Q

What is an example of an additive synergistic effect?

A

Glucagon and epinephrine on blood glucose

Both hormones have the same effect on the target cell.

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23
Q

What is a complementary synergistic effect?

A

Hormones have different effects on the target cell but work together to produce a single effect

Example: FSH and testosterone on spermatogenesis.

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24
Q

What is the permissive effect of hormones?

A

When one hormone is required for another hormone to exert its full effect

Example: Thyroid hormones are required for the full effect of growth hormone.

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25
What is an antagonistic effect?
When two hormones have opposing effects on the same target cell ## Footnote Example: Insulin and glucagon on blood glucose levels.
26
What are humoral stimuli?
Changes in blood levels of ions or nutrients that trigger hormone release ## Footnote Example: Low blood calcium levels stimulate PTH release.
27
What are neural stimuli?
Nerve fibers stimulate hormone release ## Footnote Example: Sympathetic nervous system stimulates adrenal medulla to release epinephrine and norepinephrine.
28
What are hormonal stimuli?
Hormones stimulate other endocrine glands to release hormones ## Footnote Example: Hypothalamic hormones stimulate the pituitary gland to release hormones.
29
What is primary hormone overproduction?
Caused by a problem in the gland itself.
30
What is secondary hormone overproduction?
Caused by a problem in the pituitary gland or hypothalamus that stimulates the gland to produce too much hormone.
31
What are the two causes of hormone underproduction?
* Primary gland failure * Secondary to deficiency of stimulating hormone
32
What is hormone resistance?
Failure of activation of hormone or target organ resistance.
33
What is hormone hypersensitivity?
Failure of deactivation of hormone or target organ overactivity (e.g. hyperplasia).
34
What is the purpose of endocrine testing?
Evaluate hormone levels and diagnose endocrine disorders.
35
What can endocrine testing detect?
Increased or decreased hormone levels in the blood, urine, or saliva.
36
What is the significance of circadian rhythms in endocrine testing?
Hormone levels can vary throughout the day, affecting test results.
37
When are cortisol levels typically highest?
In the morning.
38
When are cortisol levels typically lowest?
At night.
39
If hypo-secretion is suspected, when is the best time to measure hormone levels?
At the time of day when they are expected to be highest.
40
What is the primary function of the hypothalamus?
Maintains homeostasis by regulating physiological processes, including body temperature, hunger, thirst, sleep, and circadian rhythms. ## Footnote The hypothalamus plays a crucial role in maintaining the body's internal balance.
41
How does the hypothalamus communicate with the pituitary gland?
Hypothalamic hormones are released into blood vessels that connect the hypothalamus to the pituitary gland (hypophyseal portal system). ## Footnote This system allows for rapid communication between the hypothalamus and pituitary.
42
What are releasing hormones?
Hormones that stimulate the release of hormones from the anterior pituitary gland (e.g., thyrotropin-releasing hormone, corticotropin-releasing hormone). ## Footnote Releasing hormones initiate the secretion of other hormones from the pituitary.
43
What are inhibiting hormones?
Hormones that inhibit the release of hormones from the anterior pituitary gland (e.g., somatostatin inhibits growth hormone release). ## Footnote Inhibiting hormones serve to regulate and control hormone levels in the body.
44
What are neurohormones and where are they released from?
Neurohormones are produced by the hypothalamus and released from the posterior pituitary gland (e.g., oxytocin, vasopressin/ADH). ## Footnote These hormones play significant roles in various physiological processes.
45
Why is the pituitary gland referred to as the 'master gland'?
It regulates the activity of other endocrine glands. ## Footnote The pituitary gland influences numerous bodily functions through hormone regulation.
46
Where is the pituitary gland located?
At the base of the brain, just below the hypothalamus. ## Footnote Its strategic location allows it to effectively receive signals from the hypothalamus.
47
What are the two main lobes of the pituitary gland?
1. Anterior pituitary (adenohypophysis) 2. Posterior pituitary (neurohypophysis) ## Footnote Each lobe has distinct functions and hormone production roles.
48
What is the function of the anterior pituitary?
Produces and secretes hormones in response to hypothalamic releasing and inhibiting hormones. ## Footnote This lobe is crucial for regulating various physiological processes.
49
What does the posterior pituitary do?
Stores and releases hormones produced by the hypothalamus (e.g., oxytocin, vasopressin/ADH). ## Footnote The posterior lobe does not produce hormones but rather releases them into the bloodstream.
50
What characterizes the release of hormones from the pituitary gland?
Release is usually pulsatile, with peaks and troughs in hormone levels throughout the day. ## Footnote This pulsatile release is important for maintaining proper hormonal balance.
51
What are endocrine axes?
Pathways through which hormones interact and regulate physiological processes. ## Footnote These pathways are critical for understanding hormonal regulation in the body.
52
What is the hypothalamic-pituitary-target organ axis?
A key component of the endocrine system characterized by the sequence: Hypothalamus ⇒ Pituitary gland ⇒ Target organ. ## Footnote This axis illustrates the hierarchical control of hormonal functions.
53
What type of feedback is used to regulate hormone secretion?
Feedback control, specifically negative feedback and positive feedback. ## Footnote These mechanisms help maintain homeostasis in the body.
54
Fill in the blank: The hypothalamus regulates physiological processes through _______.
[hormonal signaling] ## Footnote Hormonal signaling is essential for coordinating bodily functions.
55
What is negative feedback?
A regulatory mechanism in which the output of a system inhibits or reduces its own production ## Footnote This mechanism helps maintain homeostasis by preventing excessive hormone production or activity.
56
How does negative feedback help maintain homeostasis?
By preventing excessive hormone production or activity ## Footnote When a body falls out of homeostasis, the endocrine system responds by releasing hormones to restore balance.
57
What hormone does the hypothalamus produce to initiate the menstrual cycle?
Gonadotropin-releasing hormone (GnRH) ## Footnote GnRH stimulates the anterior pituitary to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
58
What is the role of LH and FSH in the menstrual cycle?
They stimulate the ovaries to produce estrogen ## Footnote As estrogen levels rise, they exert negative feedback on the hypothalamus and pituitary gland.
59
What does high estrogen levels inhibit during the menstrual cycle?
Further release of GnRH, LH, and FSH ## Footnote This prevents excessive estrogen production and helps regulate the menstrual cycle.
60
What is positive feedback?
A regulatory mechanism in which the output of a system enhances or amplifies its own production ## Footnote This mechanism is less common in the endocrine system but plays a crucial role in certain physiological processes.
61
Provide an example of positive feedback in the human body.
Oxytocin during childbirth ## Footnote Oxytocin enhances uterine contractions, which further stimulates its release.
62
Where is the thyroid gland located?
In the neck, just below the larynx ## Footnote The thyroid gland plays a crucial role in metabolism, growth, and development.
63
What hormones does the thyroid gland produce?
Thyroid hormones T3 and T4 ## Footnote These hormones regulate the body’s metabolic rate, heart rate, and temperature.
64
What is essential for the synthesis of thyroid hormones?
Iodine ## Footnote Iodine deficiency can lead to thyroid-related health issues.
65
What types of cells compose the thyroid gland?
Follicular cells and parafollicular cells (C cells) ## Footnote Follicular cells produce T3 and T4, while parafollicular cells produce calcitonin.
66
What is the function of calcitonin?
To help regulate calcium levels in the blood ## Footnote Calcitonin lowers blood calcium levels when they are elevated.
67
What hormone does the hypothalamus release in response to a small decrease in T3 and T4 levels?
Thyrotropin-releasing hormone (TRH) ## Footnote TRH is responsible for initiating the thyroid hormone production process.
68
What does TRH stimulate in the anterior pituitary gland?
Release of thyroid-stimulating hormone (TSH) ## Footnote TSH is crucial for the stimulation of the thyroid gland.
69
What is the role of TSH in the hypothalamic-pituitary-thyroid axis?
Stimulates the thyroid gland to produce and release T3 and T4 hormones ## Footnote T3 and T4 are essential hormones for metabolism.
70
What feedback mechanism occurs as T3 and T4 levels rise?
Negative feedback on the hypothalamus and pituitary gland ## Footnote This mechanism helps regulate hormone levels in the body.
71
What does the Thyroid Function Test (TFT) Profile include?
TSH and fT4 levels in the blood ## Footnote TFT is used to assess thyroid function.
72
What are heterophilic antibodies?
Anti-species antibodies that can interfere with immunoassays ## Footnote They can lead to false results in endocrine testing.
73
What are autoantibodies?
Antibodies that target the body’s own proteins ## Footnote They can affect hormone levels and testing results.
74
What are macromolecular forms of hormones?
Examples include macroprolactin ## Footnote These forms can complicate hormone measurement.
75
What is cross-reactivity of antibodies in immunoassay?
When antibodies react with similar but non-target antigens ## Footnote This can result in inaccurate assay results.

Clinical Chemistry (25 decks)

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