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MCAT Biology and Biochemistry > Biology Chapter 5: The Endocrine System > Flashcards

Biology Chapter 5: The Endocrine System Flashcards

1
Q

What is endocrine signaling?

A

Involves the secretion of hormones directly into the bloodstream. The hormones travel to distant target tissues, where they bind to receptors and induce a change in gene expression or in cell function.

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2
Q

What are peptide hormones?

A

Composed of amino acids and are derived from larger precursors that are cleaved during posttranslational modification.

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3
Q

Can peptide hormones pass through the plasma membrane?

A

No, they are polar - instead they bind to the extracellular receptors where they trigger the transmission of a second messenger.

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4
Q

What is the speed of the peptide hormones?

A

rapid onset, but short-lived.

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5
Q

What are steroid hormones?

A

hormones derived from cholesterol

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6
Q

Can steroid hormones pass through the membrane?

A

Yes, they are minimally polar

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7
Q

Where do steroid hormones bind?

A

Either intracellular or intranuclear receptors where they promote conformational change and bind to DNA affecting the transcription of a particular gene.

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8
Q

What is the speed of steroid hormones?

A

They are slow, but are long-lived

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9
Q

Can steroid hormones travel in the blood stream alone?

A

No, they must be carried by specific proteins.

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10
Q

What are amino acid-derivative hormones?

A

Modified amino acids

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11
Q

What are examples of amino acid-derivative hormones?

A

epinephrine, norepinephrine, triiodothyronine and thyroxine

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12
Q

What are direct hormones versus tropic hormones?

A 
direct = major effects in non-endocrine tissues
tropic = endocrine tissues
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13
Q

What is the hypothalamus?

A

The bridge between the nervous and endocrine systems

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14
Q

How does the hypothalamus stimulate the anterior pituitary gland?

A

Paracrine release of hormones into the hypophyseal portal system, which connects the two organs.

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15
Q

What is the Gonadotropin-releasing hormone?

A

promotes the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

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16
Q

What does Growth hormone-releasing hormone do?

A

promotes the release of growth hormone

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17
Q

What does thyroid-releasing hormone do?

A

promotes the release of thyroid-stimulating hormone

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18
Q

What does coricotropin-releasing factor do?

A

promotes the release of adrenocorticotripic hormone

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19
Q

What does Prolactin-inhibiting factor do?

A

Inhibits the release of prolactin

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20
Q

How are oxytocin and antidiuretic hormone released?

A

Synthesized in the hypothalamus ant then travel down axons to the posterior pituitary and then are released into the blood stream.

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21
Q

What does the anterior pituitary release?

A

Tropic - FSH, LH, ACTH and TSH

Direct - prolactin, endorphins and growth hormones

22
Q

What does Follicle-stimulating hormone (FSH) do?

A

Promotes the development of ovarian follicles in females and spermatogenesis in males.

23
Q

What does luetinizing hormone (LH) do?

A

Promotes ovulation in females and testosterone production in males.

24
Q

What does Adrenocorticotropic hormone (ACTH) hormone do?

A

promotes synthesis and release of glucocorticoids from the adrenal cortex.

25
Q

What does thyroid-stimulating hormone do?

A

Promotes synthesis and release of triiodothyronine and thrroxine from the thyroid.

26
Q

What does prolactin do?

A

Promotes milk production

27
Q

What do endorphins do?

A

Decrease perception of pain and can cause euphoria.

28
Q

What does the growth hormone do?

A

Promotes growth of bone and muscle and shunts glucose to these tissues. It raises blood glucose concentration.

29
Q

What hormones does the posterior pituitary gland produce?

A

Antidiuretic hormone and oxytocin

30
Q

What does antidiuretic hormone do?

A

secreted in response to low blood volume or increased blood osmolarity and increases reabsorption of water in the collecting duct of the nephron, increasing blood volume and decreasing blood osmolarity.

31
Q

What is oxytocin?

A

Secreted during childbirth and promotes uterine contractions. It also promotes milk ejection and may be involved in bonding behavior. It has a + feedback loop.

32
Q

What does the thyroid produce?

A

Triiodothyronine and thyroxine (follicular cells produce)

Calcitonin (parafollicular cells produce)

33
Q

What does triiodothyronine and thyroxine do?

A

increase basal metabolic rate and alter the utilization of glucose and fatty acids. They are required for proper neurological and physical development in children.

34
Q

What does calcitonin do?

A

Decreases plasma calcium concentration by promoting calcium excretion in kidneys, decreasing absorption in gut and promoting calcium storage in bones.

35
Q

What does the parathyroid glands release?

A

parathyroid hormone

36
Q

What are the key parts of the parathyroid hormone?

A
  • decreases excretion of calcium by kidneys and increases bone resorption–> more blood calcium
  • activates Vitamin D
  • Promotes resorption of phosphate from bone and reduces reabsorption of phosphate in the kidney.
37
Q

What hormones does the adrenal cortex produce?

A

Glucocorticoids (cortisol and cortisone)
Mineralocorticoids (aldsterone)
Cortical sex hormones (androgens and estrogens)

38
Q

What do cortisol and cortisone do?

A

increase blood glucose concentration, reduce protein synthesis, inhibit the immune system and participate in stress response.

39
Q

What do mineralocorticoids do?

A

promote sodium reabsorption in the distal convoluted tubule and collecting duct, thus increasing water reabsorption. Aldosterone also increases potassium and hydrogen ion excretion.

40
Q

What does the adrenal medulla secrete?

A

catecholamines (epinephrine and noepinephrine – fight or flight responses)

41
Q

What does the pancreas produce?

A

Glucagon, Insulin, Somatostatin

42
Q

What is glucagon and what produces it?

A

alpha-cells, raises blood glucose levels by stimulating protein and fat degradation

43
Q

What is insulin and what produces it?

A

beta-cells lowers blood glucose by stimulating uptake by cells and anabolic processes like glycogen, fat and protein synthesis.

44
Q

What is somatostatin and what produces it?

A

delta-cells, inhibits insulin and glucagon secretion

45
Q

What do the gonads secrete?

A

testosterone, estrogen and progesterone

46
Q

What does the pineal gland secrete?

A

melatonin - helps to regulate circadian rhythms

47
Q

What do stomach cells secrete?

A

secretin, gastrin and cholecystokinin

48
Q

What does the kidneys produce?

A

erythropoietin - stimulates bone marrow to produce erythrocytes in response to low oxygen levels

49
Q

What does the atria of the heart secrete?

A

artrial natriuretic peptide - promotes excretion of salt and water in the kidneys

50
Q

What does the thymus secrete?

A

thymosin, which is important for proper T-cell development and differentiation.

MCAT Biology and Biochemistry (24 decks)

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