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McK's Science Review > Endocrine System > Flashcards

Endocrine System Flashcards

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1
Q

Glands

A

organs, known as glands that secrete hormones, signaling molecules

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2
Q

Types of hormones

A

peptides, steroids, or amino acid derivates

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3
Q

peptide hormones

A

made of amino acids, small (like ADH) to large (like insulin), derived from larger precursor polypeptides that are cleaved during posttranslational modifications –> smaller units are transported to the Golgi apparatus for further modifications that activate the hormones and direct them to the correct locations in the cell, bind to an extracellular receptor

peptide hormone–> first messenger, triggers the transmission of a second signal, known as the “second messenger”

rapid, but short-lived response, act through second messenger cascades

water soluble, don’t require carrier proteins

names often end with -in or -ine (insulin, vasopressin, thyroxine)

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4
Q

Signaling cascade

A

connection between the hormone at the surface and the effect brought about by second messenger within the cell, at each step is the possibility of amplification

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5
Q

cAMP, IP3, and calcium

A

common second messengers, cAMP can bind to intracellular targets like protein kinase A, which phosphorylates transcription factors like cAMP response element-binding protein (CREB)

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6
Q

Adenylate cyclase

A

binding of a peptide hormone triggers the receptor to either activate or inhibit an enzyme called adenylate cyclase, raising or lowering the levels of cAMP accordingly

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7
Q

steroid hormones

A

derived from cholesterol and are produced primarily by the gonads and adrenal cortex, derived from nonpolar molecules, can pass the cell membrane, impacts the DNA and transcription directly, takes longer, but changes last longer, alters amount of mRNA and protein present in a cell

common form of conformational change is dimerization (pairing of two receptor-hormone complexes)

must be carried by proteins in the blood stream, not water soluble; globulins help carry in the blood

ex. estrogen and testosterone

names often end with -one, -ol, or -oid

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8
Q

amino-acid derivative hormones

A

epinephrine, norepinephrine, triiodothyronine, and thyroxine; bind in different ways

usually derived from one or two amino acids
ex. thyroid hormones are made from tyrosine, modified by the addition of several iodine atoms

thyroid hormones–> bind intracellularly
catecholamines–> bind to a G-coupled receptor

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9
Q

catecholamines

A

epinephrine and norepinephrine, bind to a G protein-coupled receptor

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10
Q

Direct hormones

A

work directly on the target tissue

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11
Q

Tropic hormones

A

require an intermediary to act, ex. GnRH–> LH/FSH–> estrogen and testosterone; GnRH is tropic, these usually originate in the brain and anterior pituitary gland

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12
Q

Hypothalamus

A

bridge between the nervous and endocrine system, release of hormones by hypothalamus is regulated by negative feedback, secretes compounds into the hypophyseal portal system

secretes Gonadotropin-releasing hormone (GnRH), Growth hormone-releasing hormone (GHRH), Thyroid-releasing hormone (TRH), and corticotropin-releasing factor (CRF)–> causes the release

Prolactin-inhibiting factor (PIF)–> actually dopamine, causes a decrease in prolactin secretion

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13
Q

Hypophyseal portal system

A

blood vessel system that directly connects the hypothalamus with the anterior pituitary

hypophysis –> another name for the pituitary

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14
Q

Hypophysis

A

alternative name for the pituitary

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15
Q

CRF–> ACTH–> will cause the adrenal cortex to increase the level of….?

A

Cortisol

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16
Q

What does the posterior pituitary release?

A

Oxytocin and ADH/vasopressin

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17
Q

oxytocin

A

stimulates uterine contractions during labor, as well as milk letdown during lactation

has a positive feedback loop! (until delivery occurs)

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18
Q

Antidiuretic hormone (ADH)/vasopressin

A

increases reabsorption of water in the collecting ducts of the kidneys, its secreted to increase plasma osmolarity or increase concentration of solutes within the blood

secreted in response to low blood volume as sensed by baroreceptors or increased blood osmolarity (as sensed by osmoreceptors)

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19
Q

What does the anterior pituitary synthesize?

A

FLATPEG –> FLAT–> tropic PEG–> direct hormones

  1. Follicle stimulating hormone (FSH)
  2. Luteinizing hormone (LH)
  3. Adrenocorticotropic hormone (ACTH)
  4. Thyroid-stimulating hormone (TSH)
  5. Prolactin
  6. Endorphins
  7. Growth Hormone (GH)
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20
Q

GnRH–> FSH/LH–> will stimulate the?

A

Gonads (ovaries and testes)

21
Q

TRH (thyroid-releasing hormone)–> TSH (thyroid-stimulating hormone)–> will act on the …?

A

thyroid!

22
Q

prolactin

A

stimulates milk production in the mammary glands

release of dopamine from the hypothalamus will decrease its secretion

23
Q

Endorphins

A

decrease the sensation of pain

24
Q

Growth hormone

A

promotes the growth of bone and muscle

in childhood:
excess of GH will cause gigantism
deficit results in dwarfism

as an adult–> can lead to acromegaly (causes hands, feet, and head to grow when they shouldn’t for adults)

25
Q

Thyroid

A

on front surface of the trachea, sets the basal metabolic rate and promotes calcium homeostasis, releases T3 and T4 which carries out the second effect through the release of calcitonin

26
Q

Triiodothyronine (T3) and thyroxine (T4)

A

produced by the iodination of the amino acid tyrosine in the follicular cells of the thyroid, capable of resetting the basal metabolic rate of the body by making energy production more or less efficient

27
Q

Hypothyroidism

A

a deficiency of iodine or inflammation of the thyroid, thyroid hormones are secreted in insufficient amounts or not at all, needed for development, lack of them can cause cretinism

28
Q

Hyperthyroidism

A

too much thyroid hormone, can result from a tumor or thyroid overstimulation

29
Q

Calcitonin

A

tones down calcium levels in the blood, made by C-cells (parafollicular cells) in the thyroid

30
Q

PTH, parathyroid hormone

A

parathyroid hormone, made in the parathyroids that sit on the posterior surface of the thyroid, serves as an antagonistic hormone to calcitonin, raises blood calcium levels

activates vitamin D, which is required for the absorption of calcium and phosphate in the gut

31
Q

adrenal cortex secretes..?

A

corticosteroids–> steroid hormones that can be divided into three classes

  1. glucocorticoids
  2. mineralocorticoids
  3. cortical sex hormones

3 S’s
Salt (mineralocorticoids)
Sugar (glucocorticoids)
Sex (cortical sex hormones)

32
Q

Glucocorticoids

A

steroid hormones that regulate glucose levels, affect protein metabolism, cortisol and cortisone

33
Q

Mineralocorticoids

A

used in salt and water homeostasis, aldosterone (increases sodium reabsorption in the distal convoluted tubule and collecting duct), water follows sodium cations, also decreases the reabsorption of potassium and hydrogen ions in these same segments of the nephron, promoting their excretion in the urine

34
Q

Renin-angiotensin-aldosterone system

A

Decreased blood pressure causes the juxtaglomerular cells of the kidney to secrete renin, which cleaves an inactive plasma protein, angiotensinogen, to its active form, angiotensin I. Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs. Angiotensin II stimulates the adrenal cortex to secrete aldosterone

35
Q

Cortisol sex hormones

A

androgens and estrogens, testes make a lot of androgens, ovaries secrete fewer, so women are more sensitive to disorders of the cortical sex hormone production

36
Q

What does the adrenal medulla produce?

A

Epinephrine and norepinephrine (catecholamines)

37
Q

pancreas

A

hormone-producing cells are clumped together in the islets of Langerhans

  1. alpha–> glucagon
  2. beta—> insulin
  3. delta —> somatostatin
38
Q

Glucagon

A

secreted during times of fasting

when glucose levels are low, glucagon increases glucose production by triggering glycogenolysis, gluconeogenesis, and the degradation of protein and fat

CCK and gastrin can increase glucagon release from alpha cells

Glucagon levels are high when Glucose is Gone

39
Q

Insulin

A

antagonistic to glucagon, secreted when blood glucose levels are high, induces muscle and liver cells to take up glucose and store it as glycogen for later use, in addition, bc it is active when glucose levels are high, insulin stimulates anabolic processes such as fat and protein synthesis

too much can lead to hypoglycemia

40
Q

Diabetes mellitus

A

characterized by too much glucose in the blood (hyperglycemia), excessive glucose in the filtrate will overwhelm the nephron’s ability to reabsorb glucose, resulting in glucose in the urine, often have polyuria (increased urination), and polydipsia (increased thirst)

41
Q

Type 1 diabetes

A

autoimmune destruction of the beta cells of the pancreas

42
Q

Type II diabetes

A

result of receptor-level resistance to the effects of insulin, partially inherited, partially due to environmental factors

43
Q

somatostatin

A

inhibitor of both insulin and glucagon secretion, decreases GH secretion, also made in the hypothalamus, high blood glucose and amino acid concentrations stimulate its secretion

44
Q

testes

A

secrete testosterone in response to stimulation by LH and FSH, causes sexual differentiation of the male during gestation and promotes secondary sex characteristics

45
Q

ovaries

A

secrete estrogen and progesterone in response to gonadotropins, estrogen is involved in the development of the female reproductive system and secondary sex characteristics

46
Q

pineal gland

A

secretes melatonin, involved in circadian rhythms, makes you sleepy

47
Q

What produces erythropoietin?

A

Kidneys, erythropoietin stimulates bone marrow to increase production of red blood cells, response to low levels of oxygen in the blood

48
Q

What does hormone does the heart release?

A

Atrial natriuretic peptide (ANP)–> helps regulate salt and water balance, promotes the excretion of sodium and therefore increases urine volume

antagonist to aldosterone

LOWERS blood volume and LOWERS pressure, no effect on blood osmolarity

49
Q

What does the thymus release?

A

Thymosin, important for proper T cell development and differentiation, thymus atrophies by adulthood and thymosin levels drop accordingly

McK's Science Review (24 decks)

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