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Endocrine System Flashcards

1
Q

What does the endocrine system include?

A

Hypothalamus, Pituitary, Thyroid, Parathyroids, Adrenals, Pancreas, Ovaries, Testes, Pineal gland

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2
Q

What are hormones?

A
  • Made in gland(s) or cells
  • transported by blood
  • activate physiological response at distant target tissue receptors
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3
Q

What functions do hormones control?

A
  • Control of enzymatic reactions
  • Transport of ions or molecules across cell membranes
  • Gene expression and protein synthesis
  • Exert effects at very low concentrations
  • Bind to target cell receptors
  • Half-life indicates length of activity
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4
Q

What are tropic hormones?

A
  • Act on other endocrine glands
  • control of hormone secretion

Hypothalamus and anterior pituitary

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5
Q

What are non-tropic hormones?

A

Act on effector organs, e.g., thyroid, adrenals, pancreas

Thyroid, adrenals, pancreas

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6
Q

Endrocrine glands

A
  • Secrete hormones
  • Ductless
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7
Q

Neuro-secretory cells

A
  • Secrete neuro-hormones (or neuro-peptides)
  • Adrenal medulla (catecholamines)
  • Hypothalamus (posterior pituitary)
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8
Q

What are the types of hormones based on their structure?

A
  • Peptide hormones
  • Steroid hormones
  • Amine hormones
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9
Q

What is the process of peptide hormones?

A
  • Travels freely in the blood but cannot cross the cell membrane (needs a cell receptor)
  • Start as preprohormone in the rough ER (inactive and large)
  • Then become prohormone (still inactive, stored in vesicle, make final cut before release)
  • Then becomes an active hormone after final cuts to exit the cell.
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10
Q

What is the half-life of peptide hormones?

A

Short half-life

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11
Q

Peptide hormone-receptor complex

A
  • Surface receptor
  • Hormone binds: enzyme activation, or opens channels, or 2nd messenger systems
  • Cellular response
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12
Q

Peptide hormone features

A
  • Hydrophilic (water soluble)
  • Protein based
  • Can travel freely in the blood
  • Cannot enter the cell without a member receptor
  • Uses second messenger
  • Quick-acting
  • Short half life

Examples: insulin, glucagon, calcitonin, parathyroid hormone

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13
Q

Steroid hormone features

A
  • Cholesterol based
  • Lipophilic and can enter target cell
  • Must travel in blood bound to a protein
  • Uses cytoplasmic or nuclear receptors
  • Slower acting
  • Longer half life

Examples: cortisol, estrogen, and testosterone

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14
Q

How do steroid hormones act?

A

Activate DNA for protein synthesis, slow-acting, longer half-life

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15
Q

Amine hormone features

A
  • Ring structure
  • Derived from one of two amino acids
  • Tryptophan –> melatonin
  • Tyrosine –> thyroid hormones and catecholamines

Catecholamines: epinephrine, norepinephrine, dopamine

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16
Q

What is the process of peptide hormone synthesis?

A

mRNA -> Ribosome -> Preprohormone -> Prohormone -> Active hormone

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17
Q

Catecholamines behaviour similar to ________ and thyroid hormones behave similar to _________.

A

Peptides
Steroids

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18
Q

What is negative feedback in hormonal control?

A

Self-regulates hormone levels, turns off response homeostatically

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19
Q

Synergism

A
  • Multiple hormones work together
  • Effect is greater than if you just added them together

Ex: glucagon, epinephrine, cortisol

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20
Q

Permissiveness

A
  • Presence of one hormone makes the second hormone’s response greater
  • Does not go both ways
  • Needs second hormone to get full expression

Ex: thyroid hormone increases the effect of epinephrine, but epinephrine does not necessarily increase the effect of thyroid hormone

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21
Q

Antagonism

A
  • Pairs of hormones with opposing effects
  • Glucagon opposes insulin, calcitonin and parathyroid hormone
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22
Q

Blood hormone levels depend on:

A
  • Rate of hormone secretion
  • Rate of hormone degradation
  • Rate of hormone excretion (kidneys)
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23
Q

What factors can affect hormone secretion?

A
  • Emotional state
  • Disease state
  • Stress
  • Diet, sleep
  • Body cycles (circadian rhythm, menstrual cycle)
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24
Q

Three levels of endocrine control

A
  • Hypothalamic from the central nervous system (sends hypothalamus trophic hormones)
  • Pituitary stimulation (sends pituitary trophic hormones)
  • Endocrine gland stimulation (sends non-tropic hormoens)
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25
What is hyposecretion?
Too little hormone is secreted
26
What is hypersecretion?
Too much hormone is secreted
27
What are the causes of primary hyposecretion?
* Gland abnormality * Genetic factors * Dietary issues * Chemical/toxic influences * Autoimmune diseases
28
What is secondary hyposecretion?
Gland is normal but too little hormone is secreted due to decreased tropic hormone
29
What is a deficiency?
A lack of a necessary substance or hormone in the body
30
What are the symptoms of deficiency?
Varies depending on the hormone or substance involved
31
What causes hypersecretion?
Tumours, immunologic factors, primary and secondary hypersecretion
32
Define primary hypersecretion.
Too much hormone is secreted due to abnormality within the gland
33
Define secondary hypersecretion.
Excessive stimulation from outside the gland causes oversecretion
34
What is the role of the hypothalamus?
Controls the anterior pituitary and maintains homeostasis
35
What are hypothalamic releasing and inhibiting hormones?
Hormones that stimulate or inhibit anterior pituitary hormones
36
What hormones are stored in the posterior pituitary?
Oxytocin and ADH
37
Where are the hormones made for the posterior pituitary?
Hypothalamus
38
What is the function of oxytocin?
Stimulates uterine contractions and promotes milk ejection
39
What does ADH (Vasopressin) do?
Increases water reabsorption in kidney and decreases urine output ## Footnote Dehydration or high blood osmolarity
40
What is diabetes insipidus?
Condition characterized by low ADH leading to excessive urination ## Footnote Hypotension, dizziness, constipation Treatment: vasopressin replacement
41
Vascular link between the hypothalamus and anterior pituitary
* Leaves hypothalamus via the neurosecretory cell then enters the hypothalamic capillaries
42
What does the anterior pituitary secrete?
6 peptide hormones, 5 of which are tropic
43
What are gonadotropins?
FSH and LH, hormones that promote egg and sperm production, and help with estrogen and testosterone secretion
44
What does Thyroid-secreting hormone (TSH) promote?
Promotes secretion of thyroid hormones
45
What is the function of Adrenocorticotropic hormone (ACTH)?
Promotes cortisol secretion from the adrenal cortex ## Footnote Secreting hormone
46
What does prolactin act on?
Mammary glands for breast development and milk production
47
What is the effect of Growth Hormone (GH)?
Stimulates liver to release IGFs and promotes growth ## Footnote -Increased muscle -Lengthening and thickening of bones
48
What metabolic effects does Growth Hormone have?
Increases fatty acids in blood and blood glucose ## Footnote This increases the breakdown of fat stored in adipose tissue and reduces glucose uptake by muscles
49
What factors influence growth?
* Genetics * Adequate diet and sleep * Freedom from chronic disease and stress * Normal levels of growth-influencing hormones
50
Growth rate
* Not contineous * Fetal growth (hormones from placenta) * Postnatal growth spurt (first two years of life - GH) * Pubertal growth spurt (adolescence - GH)
51
Dwarfism
* Low GH (hyposecretion) * No genetic disease * Proportional growth
52
GH Hypersecretion
* Too much GH * Before growth plates close: gigantism and lengthening of bone * After growth plates close: acromegaly, thickening of bone instead
53
What is the role of the pineal gland?
Secretes melatonin and influences body clock and antioxidant activity
54
What are the two hormones produced by the thyroid gland?
Thyroid hormone (TH) and Calcitonin ## Footnote TH includes T3 and T4, which are crucial for metabolism.
55
Characteristics of the thyroid gland
* Largest pure endocrine gland * Follicles and areolar connective tissue * Produces two hormones: thyroid hormone (follicular cells) and calcitonin (parafollicular cells)
56
What is required for the synthesis of thyroid hormones?
Iodine ## Footnote Iodine is essential for the production of T3 and T4 hormones.
57
What is hyperthyroidism?
Excessive thyroxine production ## Footnote Symptoms include tachycardia, nervousness, hyperactivity, weight loss, and exophthalmus.
58
What autoimmune condition is associated with hyperthyroidism?
Grave's disease ## Footnote Treatment may include medication, radiation, and surgery.
59
What are the symptoms of hypothyroidism?
Cold and lethargic, weight gain, brittle hair and nails, mental sluggishness ## Footnote Treatment typically involves thyroid hormone replacement.
60
What is cretinism?
Low thyroid hormone in the first 2 years of life ## Footnote It leads to severe mental impairment and low muscle tone.
61
What is a simple goiter?
Enlargement of the thyroid gland ## Footnote -Can be due to hypo- or hyperthyroidism and may cause dyspnea and dysphagia. -Asymptomatic until large, leads to dyspnea and dysphagia -Iodine in diet -Surgery to decrease dysphagia and dyspnea
62
What does calcitonin do?
* Lowers blood calcium levels * Released when blood calcium is high * Decreases calcium absorption in gut * Increases kidney excretion * Promotes bone absorption
63
What hormone do parathyroid glands secrete?
Parathyroid hormone (PTH): * Antagonist to calcitonin * Released if blood calcium is low * Acts to increase blood calcium by increasing gut absorption, decreasing kidney excretion, and getting bones to release calcium
64
What is the role of Vitamin D in calcium regulation?
* Activated by PTH * Stimulates calcium and phosphate absorption from the intestine * Can be synthesized from cholesterol derivative when exposed to sunlight via liver and kidney
65
What does vitamin D deficiencies lead to?
* Rickets (children) * Osteomalacia (adults) * Decalfication of the bone * Muscle weakness * Weight loss and bone pain
66
Where is epinephrine released from?
Adrenal medulla
67
Role of epinephrine
* Longer sympathetic effect * Increased heart rate * Increased breathing * Increased metabolism
68
Which hormones are released from the adrenal cortex?
* Steroids: mineralcorticoids, glucocorticoids, androgens
69
Aldosterone
* Released if blood volume is low or Na is low * Acts on renal tubules * Plays a role in the renin-angiotension system
70
Androgens
* Secretes both male and female sex hormones * Males produce estrogen/females produce testosterone * Assisted by dehydroepiandrosterone
71
How are androgens important for men?
* Estrogen important for bone health and cholesterol * Low estrogen contributes to increased belly fat * High estrogen contributes to breast development, erectile dysfunction, infertility
72
How are androgens important for women?
* Low test may contribute to fatigue, loss of sex drive, loss of muscle, mood changes * High test contributes to male characteristics
73
What does cortisol do?
* Increases blood glucose * Increases blood fatty acids * Immunosuppressive effects * Stress hormone ## Footnote Glucocorticoid
74
What is Cushing's syndrome?
Increased cortisol levels ## Footnote Symptoms include hyperglycemia, weight gain, and poor immune function.
75
Which cells does the pancreas have?
* Exocrine cells (acinar cells) that secrete digestive enzymes * Endocrine cells (islet cells) that secrete glucagon and insulin
76
What triggers the release of insulin?
High blood glucose levels ## Footnote Insulin facilitates glucose uptake into cells and reduces blood glucose levels.
77
What is Type I Diabetes Mellitus?
* Low insulin * Insulin-dependent * Autoimmune * Requires daily injections, blood monitoring, and diet control
78
What are the symptoms of diabetes mellitus?
Frequent urination, thirst, hunger ## Footnote High blood glucose levels lead to glucose spilling into urine.
79
Feeding States
Absorptive states: * 3-4 hours after eating * Insulin is the main controller, moving nutrients into cells and storage Post-absorptive state: * 4+ hours after eating * Glucagon is the main controller, moving nutrients out of cells and storage
80
What is glucagon's role in blood glucose regulation?
Increases blood glucose levels ## Footnote It promotes gluconeogenesis and glycogenolysis when blood glucose is low.
81
What are the primary actions of insulin?
Facilitates glucose uptake, promotes glycogen formation ## Footnote Also enhances cellular uptake of fatty acids and amino acids.
82
What is insulin?
A hormone that regulates blood sugar levels ## Footnote Insulin is produced by the pancreas and plays a crucial role in glucose metabolism.
83
What is Diabetes Mellitus Type IIz/
* Low insulin response * Early: poor response to insulin, diet and exercise * Late: beta cells dysfunctional and insulin levels drop, may now need insulin injections
84
What are some complications of Diabetes Mellitus?
* Long-term tissue damage * Atherosclerosis * Diabetic retinopathy * Kidney damage * Neuropathies * Heart disease * Gestational diabetes in pregnancy ## Footnote These complications can arise from uncontrolled diabetes over time.
85
What is diabetes insipidus?
Diabetes insipidus disrupts the body's ability to regulate fluid balance, leading to excessive thirst and urination. This occurs due to a deficiency or resistance to antidiuretic hormone (ADH), also known as vasopressin. ADH helps the kidneys reabsorb water back into the bloodstream, so a lack of it or a lack of response to it results in the production of large volumes of dilute urine.

KNES260 (13 decks)

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