(M) Lec 1: Introduction to Endocrinology Flashcards

1
Q
  • A network of ductless glands that secrete hormones
  • The regulatory system of the body (for the control of different body functions)
A

Endocrine System

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2
Q

Chemical signals that regulate or control the activities of the body by being transported from one cell to another

A

Hormones

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3
Q

Types of Hormone Actions

Trasmitted/secreted via the bloodstream

A

Endocrine Hormones

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4
Q

Types of Hormone Actions

Transmitted via the GIT

A

Exocrine Hormones

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5
Q

Types of Hormone Actions

Transmitted via the neurons (neurologically-transmitted hormones)

A

Neurocrine

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6
Q

Types of Hormone Actions

Transmitted through the interstitial fluid

A

Paracrine Hormones

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7
Q

Other Types of Hormone Actions

Binds to specific receptors on the cell of origin resulting to self-regulation of its function

A

Autocrine

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8
Q

Other Types of Hormone Actions

Acts on adjacent cells by direct cell-to-cell contact

A

Juxtacrine

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9
Q

Other Types of Hormone Actions

Remains inside the synthesis of origin

A

Intracrine

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10
Q

The feedback mechanisms regulate the release of hormones from what gland?

A

Adrenal

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11
Q

Feedback Mechanisms

↑ Hormone = ↑ Activity and Production Rate

A

Positive Feedback Mechanism

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12
Q

Feedback Mechanisms

The hypothalamus releases this hormone to stimulate the anterior pituitary gland

A

Gonadotropin-releasing Hormone (GnRH)

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13
Q

Feedback Mechanisms

Upon the stimulation of the anterior pituitary, what hormones does it produce (2)?

A
  1. Luteinizing Hormone (LH)
  2. Follicle-stimulating Hormone (FSH)
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14
Q

Feedback Mechanisms

The LH and FSH are responsible for stimulating what organs?

A

Gonads (testis and ovaries)

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15
Q

Feedback Mechanisms

What sex hormones do the testes and ovaries secrete (3)?

A
  1. Testosterone (testis)
  2. Estradiol and Progesterone (ovaries)
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16
Q

Feedback Mechanisms

↑ Hormone = ↓ Activity and Production Rate

A

Negative Feedback Mechanism

Note: The signal is sent to the hypothalamus to stop the production of GnRH, LH, FSH, and sex hormones

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17
Q

Classification of Hormones

  • Are hydrophilic (water-soluble); they cannot cross the cell membrane therefore it only takes effect on the surface of cells
  • e.g. Glycoproteins and Polypeptides
A

Peptides and Proteins

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18
Q

Classification of Hormones

Glycoproteins or Polypeptides?
- FSH, HCG, TSH, Erythropoietin

A

Glycoproteins

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19
Q

Classification of Hormones

Glycoproteins or Polypeptides?
- ACTH, ADH, GH, angiotensin, calcitonin, cholecystokinin, gastrin, glucagon, insulin, melanocyte-stimulating hormone, oxytocin, prolactin, and somatostatin

A

Polypeptides

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20
Q

Classification of Hormones

  • Are hydrophobic/water-insoluble
  • Produced by the adrenal glands, ovaries, testes, and placenta
  • e.g. aldosterone, cortisol, estradiol, progesterone, testosterone, and activated vitamin D
A

Steroids

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21
Q

Classification of Hormones

  • Derived from amino acids and are intermediary between (composed of) steroids and proteins
  • Some parts are hydrophilic while some are hydrophobic
  • e.g. epinephrine, norepinephrine, T3, and T4
A

Amines

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22
Q

Endocrine Glands

  • A link between the nervous system and endocrine system
  • Serves as the “master” to the master gland (pituitary gland; secretes hormones that activate other glands)
  • This secretes “releasing hormones” while the pituitary secretes “stimulating hormones”
A

Hypothalamus

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23
Q

Endocrine Glands

Where are ADH and Oxytocin specifically produced and synthesized within the hypothalamus (2)?

A
  1. ADH - supraoptic nuclei
  2. Oxytocin - paraventricular nuclei
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24
Q

Endocrine Glands

It is a common misconception that ADH and Oxytocin are produced in the posterior pituitary gland when in fact it is produced in the hypothalamus. How did the misconception come to be?

A

Since the hypothalamus is connected to the posterior pituitary gland, its actual role is the FACILITATION OF RELEASE of ADH and oxytocin

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25
Q

Endocrine Glands

The ff. hormones are classified as what (according to their place of synthesis)?
- Thyrotropin-relasing hormones (TRH), GnRH, Somatostatin (GR-IH), Growth hormone releasing hormone (GH-RH), and Prolactin-inhibiting factor (PIF)

A

Hypophyseal Hormones

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26
Q

Endocrine Glands

Thyrotropin-relasing hormones (TRH) are capable of activating what gland?

A

Anterior Pituitary Gland

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27
Q

Endocrine Glands

Upon the activation of the anterior pituitary gland, what hormones get secreted to be released to the thyroid?

A

Thyroid-stimulating Hormone (TSH)

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28
Q

Endocrine Glands

Upon the activation of the thyroid gland by TSH, what hormones get produced (2)?

A

T3 and T4

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29
Q

Endocrine Glands

  • Responsible for the secretion of melatonin which is important for the decrease of skin pigmentation
  • The secretion of melatonin is controlled by nerve stimuli
A

Pineal Gland

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30
Q

Endocrine Glands

  • Aka hypophysis or the Master Gland
  • Hormones are regulated by hypothalamic secretions
  • Has an anterior and posterior portion
A

Pituitary Gland

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31
Q

Endocrine Glands

The anterior and posterior pituitary glands are also known as? (2)

A
  1. Anterior - adenohypophysis (the true endocrine gland)
  2. Posterior - neurohypophysis
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32
Q

Endocrine Glands

TOF: The posterior pituitary gland produces ADH and Oxytocin

A

False (it is merely released; it is produced in the hypothalamus)

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33
Q

5 Types of Cells in the Anterior Pituitary Gland

An example is the growth hormone

A

Somatotrophs

34
Q

5 Types of Cells in the Anterior Pituitary Gland

An example is prolactin

A

Lactotrophs

35
Q

5 Types of Cells in the Anterior Pituitary Gland

An example is TSH

A

Thyrotrophs

36
Q

5 Types of Cells in the Anterior Pituitary Gland

Examples are FSH and LH

A

Gonadotrophs

37
Q

5 Types of Cells in the Anterior Pituitary Gland

An example is proprioomelanocortin (POMC) which is later on converted to ACTH, beta-endorphin, and beta-lipotropin

A

Corticotrophs

38
Q

Hormones of the Anterior Pitutary

  • Structurally similar to prolactin and human placental lactogen
  • Is controlled by GH-RH and GH-IH (somatostatin) produced by the hypothalamus
  • Its overall metabolic effect is to metabolize fat stores while conserving glucose
A

Growth Hormone

39
Q

Growth Hormone

Increases or Supresses GH?
1. Hypoglycemia
2. Hyperglycemia

A
  1. Increases GH (to conserve glucose)
  2. Supresses GH (to reduce glucose)
40
Q

Growth Hormone

Insulin-like Growth Factor 1 is also known as?

A

Somatomedin

41
Q

Growth Hormone

This is an important stimulator for the secretion of GH

42
Q

Growth Hormone

What is the major stimulant of the growth hormone?

43
Q

Growth Hormone Deficiency

  • The most common cause of dwarfism in children
  • Aka true dwarfism/pituitary dwarfism; there is a problem with the anterior pituitary
A

Idiopathic Growth Hormone Disorder

44
Q

Growth Hormone Deficiency

The ff. types of dwarfism involve the dysfunction of what?
- Laron dwarfism and African pygmy dwarfism
- Prevents the production of somatomedin by the liver

A

Growth Hormone Receptors

45
Q

Growth Hormone Deficiency

An excess of this leads to dwarfism as this has anti-GH activity

A

Glucocorticoids

46
Q

Growth Hormone Deficiency

In this condition, hypothyroidism is evident (decreased T3 and T4) as well as mental retardation

47
Q

Growth Hormone Deficiency

  • The most common etiology in adult cases of growth factor deficiency
  • An onset type of GH deficiency
  • A tumor blocks the release of GH
A

Pituitary Adenoma

48
Q

Growth Hormone Excess

  • A pituitary tumor is the cause for the hypersecretion of GH
  • Happens pre-puberty before the closure of epiphyseal plates of long bones
49
Q

Growth Hormone Excess

  • Occurs after puberty
  • There is enlargement of the hands and feet, coarse facial features, visceromegaly (cardiomegaly), skin thickening, osteoarthritis, and hyperglycemia
A

Acromegaly

50
Q

Laboratory Diagnosis of GH Disorders

What analytical method is commonly used?

A

Chemiluminescent assays

51
Q

Laboratory Diagnosis of GH Disorders

  • Blood is collected from the patient after a complete ____-minute rest
  • (Fasting/Non-fasting) specimen is required
A
  1. 30
  2. Fasting (atleast 8 hours)
52
Q

Laboratory Diagnosis of GH Deficiencies

  1. What is the screening test?
  2. What are the 2 confirmatory tests?
A
  1. Physical Activity Test
  2. Insulin Tolerance and Arginine Stimulation Test
53
Q

Confirmatory Tests for GH Deficiencies

  • The former gold standard for the detection of GH deficiencies
  • There is induced hypoglycemia by a chemical (IIH)
  • Undergoes a 24-hour or nighttime monitoring
  • Normal values for adults are > 5 ng/mL while for children it’s > 10 ng/mL
A

Insulin Tolerance Test

Note: Hypoglycemia is the most potent stimulus for GH

54
Q

Confirmatory Tests for GH Deficiencies

  • Also undergoes 24-hour or nighttime monitoring
  • Has a normal reference value of > 4.1 ng/mL
A

Arginine Stimulation Test

55
Q

Confirmatory Tests for GH Excess (Suppression Tests)

This screening test is ↑ in Acromegaly but ↓ in GH deficiency

A

Somatomedin C/ IGF-1 Test

56
Q

Confirmatory Tests for GH Excess (Suppression Tests)

  • Makes use of 75g of the OGTT load
  • A baseline glucose level (FBS) is collected and then after that it’s the GH measurement every 30 minutes for 2 hours (total of 5 samples total)
  • The normal result is < 1 ng/mL while > 1 ng/mL is indicative for acromegaly
A

Glucose Suppression Test

57
Q

Hormones of the Anterior Pitutary

Refers to FSH and LH which are markers for diagnosing fertility and menstrual cycle disorders

A

Gonadotropins

58
Q

Gonadotropins

FSH or LH?
1. In males - helps Leydig cells produce testosterone
2. In males - aids in spermatogenesis
3. In females - for ovulation and final follicular growth and androgen (estrogen and progesterone) synthesis by thecal cells

59
Q

Gonadotropins

Increased LH, FSH, or both?
1. Lack of estrogen after menopause
2. During premature menopause

A
  1. Increased for both
  2. Increased FSH
60
Q

Hormones of the Anterior Pitutary

  • Important for the stimulation of the follicular thyroid cells to produce T3 and T4 (aka thyrotropin)
  • The main stimulus for the uptake of iodide by the thyroid gland
  • Composed of mono-covalently linked alpha and beta subunits
A

Thyroid Stimulating Hormone (TSH)

61
Q

Thyroid Stimulating Hormone (TSH)

Alpha or Beta Subunit?
1. For hormonal activities
2. TSH, LH, FSH, and HCG

A
  1. Beta
  2. Alpha
62
Q

Hormones of the Anterior Pitutary

  • A single chain peptide without disulfide bonds
  • Produced in response to low serum cortisol (positive feedback)
  • A regulator of adrenal androgen synthesis
  • The highest levels are found between 6am to 8am while the lowest are found between 6pm to 11pm (diurnal variation)
A

Adrenocorticotrophic Hormone (ACTH)

63
Q

Cushing’s Disease vs. Syndrome

  1. Characterized by increased ACTH and cortisol
  2. Characterized by decreased or normal ACTH but with increased cortisol (there is a problem with the adrenal glands)
A
  1. Cushing’s Disease
  2. Cushing’s Syndrome
64
Q

Hormones of the Anterior Pitutary

  • Increased in cases of Addison’s disease, ectopic tumors, after protein-rich meals, and Cushing’s disease
  • Deficiency of this presents with atrophy of the zona glomerulosa and reticularis of the adrenal cortex
A

Adrenocorticotrophic Hormone (ACTH)

65
Q

Hormones of the Anterior Pitutary

  • A pituitary lactogenic hormone (stimulates the mammary glands to produce milk), stress hormone, and direct effector hormone
  • Is majorly inhibited by dopamine and results to hypogonadism when in excess
66
Q

Hormones of the Anterior Pitutary

This in increased in cases of: pituitary adenoma, infertility, amenorrhea, galactorrhea, acromegaly, renal failure, PCOS, cirrhosis, and primary and secondary hypothyroidism

67
Q

Hormones of the Anterior Pitutary

Its physiologic stimuli include exercise, sleep, stress, pain, and nipple stimulation during breastfeeding

68
Q

Hormones of the Anterior Pitutary

Its pharmacologic stimuli include Verapamil, Phenothiazines, Olanzapine, Prozac, Cimetidine, and Opiates

69
Q

Endocrine Glands

  • Aka neurohypophysis
  • Can only release hormones that are produced in the hypothalamus (oxytocin and vasopressin/ADH)
A

Posterior Pituitary Gland

70
Q

Hormones of the Posterior Pitutary

  • A nonapeptide
  • Secreted in association with a carrier protein
  • Functions for milk ejection and the stimulation of uterine contractions at term (aka the Fergusson reflex)
71
Q

Hormones of the Posterior Pitutary

  • Aka Arginine-Vasopressin or ADH
  • Also a nonapeptide
  • The target tissues are the DCT and collecting tubules of the kidneys for water reabsorption
A

Vasopressin

72
Q

Hormones of the Posterior Pitutary

Its physiologic stimuli for secretion/production are: decreased BP (main stimulus), nausea, hypoglycemia, hypercarbia, and nicotine

A

Vasopressin

73
Q

Hormones of the Posterior Pitutary

Its physiologic stimuli to release incudes: dehydration, physical stress, emotional stress, and surgery

A

Vasopressin

74
Q

Hormones of the Posterior Pitutary

The ff. are inhibitors for the release of what hormone?
- Ethanol, cortisol, lithium, and demeclocycline

A

Vasopressin

75
Q

Disorders of Vasopressin

  • Excess ADH leads to excess water in the body
  • Manifests with hyponatremia and hypo-osmolality (dilution effect due to excess water)
A

Syndrome of Inappropriate ADH Secretion (SIADH)

76
Q

Disorders of Vasopressin

A condition correspondent to ADH deficiency leading to polyuria, polydipsia, and polyphaga (3Ps)

A

Diabetes Insipidus

77
Q

Disorders of Vasopressin (Types of DI)

Neurogenic or Nephrogenic DI?
1. ADH is deficient but with normal receptors
2. ADH is normal but with defective receptors (resistance to ADH action)

A
  1. Neurogenic
  2. Nephrogenic
78
Q

Disorders of Vasopressin (Types of DI)

Give the other names of neurogenic diabetes insipidus

A

True/Hypothalamic/Central Diabetes Mellitus

79
Q

Laboratory Diagnosis of Diabetes Insipidus

  • Aka overnight water deprivation test
  • Should be NPO for 8-12 hours
  • A level of < 300 mOsm/kg is indicative for DI since it should increase overnight if the ADH is normal
  • The normal level is 275-295 mOsm/kg
A

Concentration Test

80
Q

Laboratory Diagnosis of Diabetes Insipidus

Neurogenic or Nephrogenic?
1. If ADH is decreased and you administer exogenous ADH = Rapid water reabsorption
2. If ADH is normal or increased and you administer exogenous ADH = No effect on reabsorption

A
  1. Neurogenic
  2. Nephrogenic