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Chapter 18: The Endocrine system > 18.1 General principles of Endocrinology > Flashcards

18.1 General principles of Endocrinology Flashcards

1
Q

The endocrine system regulates activities that require ___________ instead of _________

A

duration, speed (Nervous sytem)

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2
Q

What are the secretions that endocrine glands release?

A

hormones

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3
Q

Define hormone

A

A hormone is a blood-borne chemical messenger that acts on target cells located far away from the endocrine gland that secretes it

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4
Q

What are the three glands that are closely associated with the brain that make up the central endocrine glands?

A
  1. Hypothalamus
  2. Pituitary gland
  3. Pineal gland
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5
Q

What are the four endocrine glands that solely have endocrine functions?

A
  1. Pituitary gland
  2. Thyroid gland
  3. Parathyroid gland
  4. Adrenal gland
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6
Q

What are the 14 endocrine glands that have mixed functions?

A
  1. Pineal gland
  2. Hypothalamus
  3. heart
  4. Pancreas
  5. Liver
  6. Ovaries
  7. Testes
  8. Kidneys
  9. Adipose tissue
  10. skin
  11. Duodenum
  12. Stomach
  13. Thymus gland
  14. Placenta
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7
Q

What is endocrinology?

A

It is the study of how endocrine hormones facilitate homeostatic chemical adjustments and other activities.

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8
Q

What does it mean when it is said that target cells have specificity?

A

It means that only specific target cells will respond to a specific hormone. This is due to the receptors on the target cells that bind to specific hormones

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9
Q

What are the two classifications of hormones based on their solubility?

A

Hydrophilic and Lipophilic

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10
Q

What are the three types of hydrophilic hormones

A

peptide hormones, catecholamines, indoleamines

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11
Q

What are peptide hormones?

A

They are chains of amino acids of varying lengths (the most abundant category of hormones). They cannot enter the target cells on their own so they combine with membrane receptors that initiate the signal transduction process.

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12
Q

Talk about the receptor binding of hydrophilic hormones and how they act on the target cells.

A

they primarily bind to receptors on the cell surface of the target cell and act through second-messenger systems altering the preexisting proteins (eg enzymes) within the target cell to produce a physiological response.

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13
Q

What are catecholamines?

A

They are hormones derived from the amino acid tyrosine and are produced by the adrenal medulla

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14
Q

What are Indoleamines?

A

They are hormones derived from the amino acid tryptophan and are produced by the pineal gland

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15
Q

What is a thyroid hormone?

A

An iodinated derivative of tyrosine produced by the thyroid gland.

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16
Q

What are steroid hormones?

A

They are neutral lipids derived from cholesterol and produced by the adrenal cortex and reproductive glands

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17
Q

What are the 2 divisions of lipophilic hormones?

A

Steroid hormones and thyroid hormones

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18
Q

Since lipophilic hormones are hydrophobic, how are they transported?

A

They bind to plasma proteins which aid in their transport

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19
Q

Talk about the receptor binding of lipophilic hormones and how they act on the target cells.

A

They penetrate target cells and bind to intracellular receptors (remember they easily pass through the plasma membrane) activating genes to form new proteins within the target cell leading to the desired physiological response.

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20
Q

Compare the circulation of hydrophilic and lipophilic hormones

A

hydrophilic- circulate in the blood largely dissolved by plasma
lipophilic- bound to plasma proteins

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21
Q

Endocrine glands vs Exocrine glands

A

endocrine glands- They are ductless glands that transport their hormones via the bloodstream
exocrine glands- They secrete their hormones through ducts onto the body’s surfaces

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22
Q

What is the overall function of the nervous system?

A

It is responsible for providing rapid, short-term, precise responses in response to external stimuli.

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23
Q

What is the overall function of the endocrine system?

A

It manages processes that require sustained regulation, primarily focusing on maintaining homeostasis by regulating nutrient metabolism, water and electrolyte balance, promoting growth, and facilitating reproductive function. It also collaborates with the autonomic nervous system to regulate the circulatory and digestive systems.

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24
Q

What is a tropic hormone?

A

It is a hormone that regulates the production and secretion of other hormones.

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25
Q

What is meant by “tropic hormones have trophic action”

A

It means that these hormones have growth-promoting actions for these other hormones that they regulate to maintain the structural integrity of their glands

26
Q

define atrophy

A

is the decrease in the size or wasting away of a tissue, organ, or body part, typically due to reduced cell size, loss of cells, or diminished function

27
Q

What are the 7 factors that make the endocrine system complex?

A
  1. Multiple hormones from a single gland
  2. Hormone released by multiple glands
  3. Multiple effects of a single hormone
  4. cyclic secretion patterns
  5. Multiple hormone influence on a single target cell
  6. Dual role of chemical messenger
  7. Organs with dual functions
28
Q

What are the 4/5 factors that influence the effective plasma concentration of the free, biologically active form of a hormone?

A
  1. Rate of secretion
  2. Metabolic activation or conversion
  3. Binding of plasma proteins (transport)
  4. Rate of removal (Metabolic inactivation and excretion)
29
Q

What is the primary function of most hormones?

A

To regulate various homeostatic activities.

30
Q

The response to a hormone depends on?

A

The availability and sensitivity of its receptors on target cells

31
Q

What are the 6 factors that regulate hormones?

A
  1. Secretion and stimulation
  2. Feedback regulation
  3. Paracrine and autocrine regulation
  4. Hormonal rhythm and pulse
  5. Hormonal transport and degradation
  6. Hormonal action through receptors
32
Q

What are the three types of stimuli that are related to stimulation and secretion?

A

Hormonal, Humoral and Neural

33
Q

What is humoral stimuli?

A

secretion of a hormone is directly proportional to changes in blood levels of ions and nutrients (concentrations)

34
Q

What is Neural stimuli?

A

Usually external stimuli. It is when neural fibers stimulate hormone release. (eg fight or flight)

35
Q

What is hormonal stimuli?

A

When an endocrine gland releases hormones in response to hormones produced by another gland

36
Q

What are the three most common mechanisms of control that adjust the plasma concentration of hormones based on the body’s needs?

A
  1. Negative feedback control
  2. Neuroendocrine reflexes
  3. Diurnal (circadian) rhythms
37
Q

Explain negative feedback control

A

This mechanism ensures that hormone secretion into the plasma is kept within a narrow range. When hormone secretion is low, this mechanism stimulates increased hormone secretion. Similarly, when hormone secretion is too high, the mechanism decreases the secretion of the hormone.

38
Q

Explain neuroendocrine reflexes

A

These involve both neural and hormonal responses to external stimuli, resulting in sudden hormone secretion

39
Q

Give an example of a neuroendocrine reflex

A

The sympathetic nervous system triggering the adrenal medulla to secrete epinephrine during stress.

40
Q

Explain diurnal (circadian) rhythms

A

Hormone levels fluctuate over a 24 hour cycle in response to the body’s internal biological clock. These rhythms are synchronized with external cues, like the light-dark cycle, ensuring hormone levels align with daily activity patterns.

41
Q

Give an example of the diurnal rhythm

A

cortisol levels rise at night, peak in the morning, and drop throughout the day.

42
Q

What is paracrine and autocrine regulation

A

Thy are local regulation systems, often involving growth factors, they play critical roles in all tissues.

43
Q

What is paracrine regulation

A

it refers to factors released by one cell that act on an adjacent cell in the same tissue

44
Q

What is autocrine regulation

A

the action of a factor on the same cell from which it is produced

45
Q

What is intracrine regulation

A

Refers to effects within a cell

46
Q

What are the 3 things that endocrine disorders arise from

A
  1. hyposecretion
  2. Hypersecretion
  3. Decreased target-cell responsiveness
47
Q

What is primary hyposecretion

A

It occurs when an endocrine secretes insufficient amounts of a hormone due to an internal abnormality within the gland itself

48
Q

What is secondary hyposecretion

A

This occurs when the endocrine gland is normal but secretes too little amounts of hormone due to a deficiency of its tropic hormone

49
Q

What are the 7 causes of hyposecretion? explain each

A
  1. Genetic- an inborn absence of an enzyme for hormone synthesis
  2. dietary- Insufficient intake of essential nutrients
  3. Chemical/toxic- exposure to toxins that damage endocrine glands
  4. Immunologic- autoimmune conditions where antibodies destroy glandular tissue
  5. other diseases- conditions like cancer and tuberculosis that may consequently damage endocrine glands
  6. latrogenic- physician-induced causes, such as surgical removal of an endocrine gland
  7. Idiopathic- causes that remain unknown despite investigation
50
Q

What is primary hypersecretion

A

The endocrine gland itself secretes too much hormone due to an intrinsic effect

51
Q

What is secondary hypersecretion

A

Excess hormone secretion by the endocrine gland driven by external stimulation of the gland since the gland itself is normal.

52
Q

What are the three causes of hypersecretion? explain each

A
  1. tumors: Neoplastic growth that bypass normal regulatory mechanisms resulting in continuous hormone release
  2. Immunologic factors: Abnormal antibodies that excessively stimulate hormone production
  3. Substance abuse: Use of anabolic steroids among athletes, leading to increased hormone levels to promote muscle growth ( eg GH)
53
Q

What is abnormal target-cell responsiveness

A

This is when target cells do not adequately respond to hormones, despite normal plasma hormone concentrations

54
Q

explain the cause of abnormal target-cell responsiveness

A

Inborn receptor deficiency: This refers to a genetic condition where a person is born with either non-functional or missing receptors for specific hormones

55
Q

A target cell’s response depends on?

A

The number of occupied receptors is influenced by the hormone plasma concentration and receptor availability

56
Q

Explain what down-regulation is

A

It is when target cells are desensitised to prevent them from overreacting to high hormone levels. The number of receptors on the target cells is reduced.

57
Q

Explain the mechansim of down regulation in terms of insulin

A

Insulin binds to its receptors, it triggers a cellular response and promotes receptor-mediated endocytosis of the hormone-receptor complex.
This complex is then degraded by lysosomal enzymes, leading to reduced numbers of rerceptors on the cell surface..
The rate of the receptor synthesis does not keep pace with degradation, resulting in decreased sensitivity to insulin over time

58
Q

What are the three types of hormonal interactions

A

Permissiveness, synergism, antagonism

59
Q

Explain what permissiveness is

A

One hormone has to be present in sufficient amounts in order to enable another hormone to exert its full effect.

60
Q

Explain what synergism is

A

This is when multiple hormones work together to produce a greater effect than the combined effect of the individual hormones

61
Q

Explain what antagonism is

A

One hormone can inhibit the action of another hormone by causing a reduction in the latter’s receptor availability

62
Q

What are the body’s two regulatory systems

A

Nervous and Endocrine

Chapter 18: The Endocrine system (4 decks)

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