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Biology > Chapter 5: The Endocrine System > Flashcards

Chapter 5: The Endocrine System Flashcards

1
Q

Peptide hormones

A
  • Made up of amino acids
  • Range in sizes
  • Are charged, hence cannot pass through the plasma membrane
  • Must bind receptor to transduce signal
  • Considered 1st messenger
  • Generally water soluble –> can travel in bloodstream
  • Quick on and off
  • Relatively short-lived effects
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2
Q

Steroid hormone characteristics

A
  • Derived from cholesterol
  • Are not charged and can pass through the plasma membrane.
  • Receptors are usually intracellular or intranuclear
  • Not water soluble – need to be carried in bloodstream
  • Following a conformational change, its receptor can bind directly to DNA, resulting in increase/decrease transcription of certain proteins.
  • Slow acting
  • Long-lasting effects
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3
Q

Amino acid derivative hormones

A
  • Derived from 1-2 amino acids with a few modifications.
  • This family of hormones has less predictable chemistry than other families.
  • Catecholamines bind to GPCRs
  • Thyroid hormones bind intracellularly
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4
Q

Direct hormones

A

Are secreted and act directly on the target tissue.

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5
Q

Tropic hormones

A
  • Require an intermediary to act.

- Originate in the brain and anterior pituitary.

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6
Q

Hypothalamus

A
  • Bridge between the nervous and endocrine systems
  • Receives inputs from a wide variety of sources.
  • Hormone release is regulated by negative feedback, hence, it must have receptors for the final product of its pathway.
  • Sends hormones through axonal projections to the posterior pituitary.
  • Sends (tropic) hormones through the hypophyseal system to the anterior pituitary.
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7
Q

Gonadotropin-releasing hormone (GnRH) → ____________.

A

follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

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8
Q

Growth hormone-releasing hormone (GHRH) → ____________.

A

growth hormone (GH)

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9
Q

Thyroid-releasing hormone (TRH) → ________________

A

thyroid-stimulating hormone (TSH)

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10
Q

Corticotropin-releasing factor (CRF) → ___________.

A

adrenocorticotropic hormone

ACTH

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11
Q

What is the hypophyseal portal system?

A

A blood vessel system that directly connects the hypothalamus to the anterior pituitary.

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12
Q

Upon receiving projections from the hypothalamus, what hormones does the posterior pituitary produce?

A

Oxytocin and ADH/vasopressin

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13
Q

Which hormones are produced by the anterior pituitary?

A

Tropic: FSH,LH, ACTH TSH
Direct: prolactin, endorphins, GH

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14
Q

List the 2 main functions of the thyroid.

A
  1. Setting metabolic rate (through T3 & T4)

2. Regulating calcium (through calcitonin)

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15
Q

In signaling cascades, what are some common 2* messengers?

A
  1. IP3
  2. Ca2+
  3. cAMP
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16
Q

What is the signaling mechanisms of catecholamines? What about thyroid hormones?

A

Through GPCRs; Through direct intracellular binding.

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17
Q

What are direct hormones?

A

Hormones that upon release, act directly on their target tissue. Ex: insulin release by the pancreas causes increased glucose uptake by muscle cells.

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18
Q

What are tropic hormones? Where do they originate?

A

Hormones that need an intermediary to act/have their effect. They usually originate in the brain and anterior pituitary (these areas are involved in coordination of multiple processes within the body).

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19
Q

What is the difference in hormones received by the APG and the PPG, from the hypothalamus?

A 
APG = connected through hypophyseal blood vein system
PPG = receives axonal projections from hypothalamus.
20
Q

What is ADH’s function?

A

Water reabsorption in the collecting ducts of the kidney in response to increased plasma osmolarity.

21
Q

How does milk production occur?

A

Nipple stimulation causes activation of the hypothalamus which causes:

  1. Oxytocin release from the PP, which causes contraction of the smooth muscle of the breast, resulting in milk ejection from the nipple, and
  2. Stopping of DA release (from hypothalamus), which causes the AP to release prolactin which allows milk production and regulation of the milk supply.
22
Q

What are some conditions that can develop from abnormal production of GH?

A

Before epiphyseal plates close:
- Excess = gigantism
- Deficit = dwarfism
After epiphyseal plates close (usually in adulthood) = acromegaly

23
Q

What is ADH’s function?

A
  • Increase blood volume by increasing water permeability in the collecting ducts of the nephron.
  • It is released in response to low blood volume or increased blood osmolarity.
24
Q

What are the two major functions of the thyroid gland? How are they achieved?

A
  1. setting basal metabolic rate (through T3 & T4)
  2. Ca2+ homeostasis (through calcitonin)
    They are achieved by 1) making energy production more or less efficient, as well as altering the utilization of glucose and fatty acids.
25
Q

What is hypothyroidism and what causes it?

A

It is an insufficient secretion of thyroid hormones caused by deficiency in iodine, or inflammation of the thyroid gland.

26
Q

What is hyperthyroidism and what causes it?

A

It is an excess of thyroid hormone that may result from a tumor or overstimulation of the thyroid.

27
Q

What is calcitonin’s function? How does it achieve this?

A

Decrease plasma Ca2+ levels. It achieves this by increasing Ca2+ absorption in the kidneys, reducing absorption in the gut, and increased storage of Ca2+ in bones.

28
Q

What is PTH’s function? How does it achieve this?

A

PTH is essentially the antagonist hormone to calcitonin. It decreases Ca2+ absorption in the kidneys, increases absorption in the gut, and decreases storage in bones. It also activates VitD which is important for Ca2+ PO4 absorption in the gut.

29
Q

What are corticosteroids and where are they produced?

A

They are steroid hormones, produced in the adrenal cortex, that can be divided into 3 functional groups (glucocorticoids, mineralocorticoids, and cortical sex hormones).

30
Q

Describe the functions of glucocorticoids. Give an example.

A
  1. regulate glucose levels
  2. affect protein production

Two well-known: cortisol and cortisone. They raise blood glucose by increasing gluconeogenesis and decreasing protein production. They can also decrease inflammation and immunologic responses.
Cortisol = stress hormone; inc. glc levels in case of need to respond quickly to dangerous stimulus.

31
Q

What is the main function of mineralocorticoids? Give an example of one.

A

Salt and water homeostasis.
The most noteworthy mineralocorticoid is aldosterone. It increases Na+ reabsorption in the distal convoluted tubule and collecting duct of the nephron. The result is increase in blood volume and pressure without a change in osmolarity.

32
Q

How does the renin-angiotensin-aldosterone system work?

A
  1. Decreased bp causes the juxtaglomerular cells to secrete renin which
  2. cleaves the inactive plasma protein angiotensinogen to its active form angiotensin I.
  3. Angiotensin I is the converted into angiotensin II by ACE in the lungs.
  4. Angiotensin II then stimulates the adrenal cortex to secrete aldosterone.
33
Q

Give examples of cortical sex hormones

A

Testosterone and estrogens.

* especially important for females - imbalances can cause ambiguous or masculinized genitalia

34
Q

The Islets of Langerhans are composed of what types of cells? What hormones do each produce?

A
  • alpha: glucagon
  • beta: insulin
  • delta: somatostatin
35
Q

What is glucagon’s function?

A

Increase glucose availability by degradation of fats and protein, conversion of glycogen to glucose, and production of new glucose through gluconeogenesis.

  • It is released in times of fasting
36
Q

What is insulin’s function?

A

Induce muscle and liver cells to take up glucose and store as glycogen for later use. It stimulates anabolic pathways such as fat and protein synthesis.

37
Q

What is hypoglycemia?

A

It is low blood glucose concentration caused by an excess of insulin.

38
Q

What is hyperglycemia, and what is it a result of? In turn, what disorder does it cause?

A

Hyperglycemia is an excess of blood glucose caused by insufficient insulin (weather by underproduction, insufficient secretion or insensitivity to). It leads to diabetes mellitus.

39
Q

Describe the two types of diabetes mellitus.

A

DM I (Insulin-dependent): caused by autoimmune destruction of B-cells of the pancreas. These individuals secrete/have little to no insulin because the majority of their B-cells have been destroyed.

DM II (non-insulin-dependent): it is caused by receptor-level resistance to the effects of insulin. Partially inherited, partially due to environmental factors - high-carb diets and obesity.

40
Q

What is the function of somatostatin?

A

Inhibits both insulin and glucagon secretion.

41
Q

What is the pineal gland’s function? Which hormone does it secrete and what is its function?

A
  • It is involved in circadian rhythms through stimulus from retinal projections that detect light intensity.
  • When low intensity light is detected, it secretes melatonin, which promotes, at least in part, sleepiness.
42
Q

What is the atrial natriuretic peptide (ANP)?

A
  • Hormone released by the heart to help regulate salt/water balance.
  • It is released in response to stretch in atrial cells from excess blood volume. ANP promotes excretion of sodium, which increases urine volume.
  • Result = no change in blood osmolarity with a decrease in bp and vol.
  • It is functionally opposite to aldosterone.
43
Q

Follicle-stimulating hormone (FSH)

A
  • Peptide

- Stimulates follicle maturation in females; spermatogenesis in males

44
Q

Luteinizing hormone

LH

A

Peptide Stimulates follicle
maturation in females;
spermatogenesis in
males

45
Q

Adrenocorticotropic

hormone (ACTH)

A

Peptide Stimulates the adrenal
cortex to synthesize
and secrete glucocorticoids

Biology (5 decks)

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