Endocrine System Flashcards

1
Q

What are hormones?

A

Molecules produced by the endocrine system.

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2
Q

Function of hormones

A
  1. Send messages to parts of the body
  2. Maintain homeostasis
  3. Regulate body’s processes (hunger, bp, sex drive)
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3
Q

Exocrine Glands

A

Secrete through ducts to the outside of the body
Ex: digestive enzymes

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4
Q

Endocrine Glands

A

Lack ducts and secrete hormones into the blood

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5
Q

Endocrine System

A

Consists of ductless glands scattered throughout the body. These glands secrete hormones which travel through blood to target cells.
- Target cells have receptors for binding with specific hormone
- Regulates or directs particular function

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6
Q

Hydrophilic Hormones

A

Peptide hormones and catecholamine’s, water loving

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7
Q

Lipophilic Hormones

A

Steroid hormones and thyroid hormone, lipid loving

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8
Q

Endocrine only function

A

Pituitary, parathyroid, thyroid, and the adrenal gland

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9
Q

Mixed function

A

Pineal, hypothalamus, thymus, heart, stomach, pancreas, duodenum, kidney, skin, adipose tissue, ovaries, placenta, and testes

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10
Q

Influences of concentration of hormones in plasma

A
  1. Hormone rate of secretion
  2. Rate of metabolic activation or conversion
  3. Transport (binding to plasma proteins)
  4. Inactivation (excretion)
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11
Q

Regulation of secretion

A
  1. Negative feedback
  2. Neuroendocrine reflexes ability of nervous system to regulate secretion
  3. Diurnal (circadian) rhythms
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12
Q

Endocrine dysfunction

A

Commonly result from abnormal plasma concentrations of a hormone via inappropriate rates of secreation

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13
Q

Types of endocrine dysfunction

A
  1. Hyposecretion
  2. Hypersecretion
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14
Q

Hyposecretion

A

Too little hormone is secretion

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15
Q

Primary hyposecretion

A

Too little hormone is secreted because of abnormality within gland

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16
Q

Secondary hyposecretion

A

Too little secretion of hormone due to deficiency of its tropic hormone, no problem with gland

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17
Q

Hypersecretion

A

Too much hormone is secreted

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18
Q

Causes of hypersecretion

A
  1. Tumors that ignore normal regulatory input and continuously secrete excess hormone
  2. Immunologic factors
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19
Q

Primary hypersecretion

A

Too much hormone is secreted due to abnormality within gland

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20
Q

Secondary hypersecretion

A

Excessive stimulation from outside the gland causes over-secretion

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21
Q

How can hormones influence activity of another hormone at given target cell?

A
  1. Permissiveness
  2. Synergism
  3. Antagonism
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22
Q

Permissiveness

A

One hormone must be present in adequate amounts for full exertion of another hormone’s effect

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23
Q

Synergism

A

Occurs when actions of several hormones are complimentary
- Combined effect is greater than the sum of their separate effects

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24
Q

Antagonism

A

Occurs when one hormone causes loss of another hormone’s receptors
- Reduces effectiveness of second hormone

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25
Q

Hypothalamus

A

Endocrine organ (secretes several hormones); most of them affect the pituitary

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26
Q

Pituitary Gland

A

Pea-sized gland connected to the hypothalamus via the infundibular stalk
- Posterior pituitary
- Anterior Pituitary

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27
Q

Posterior Pituitary

A

Neurohypophysis; composed of nervous tissue

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28
Q

Anterior Pituitary

A

Adenohypophysis; consists of glandular epithelial tissue

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29
Q

What is released from the pituitary gland?

A

Human growth hormone (hGH)
Adrenocorticotropin (ACTH)
Thyroid stimulating hormone (TSH)
Gonadotropic hormones
- Luteinizing hormone (LH)
- Follicle stimulating hormone (FSH)
Prolactin (PRL)
Vasopressin
Oxytocin

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30
Q

Magnocellular Neurons

A

Secrete two hormones (neurohormones); vasopressin and oxytocin; synthesized and packaged into vesicles that are transported to posterior pituitary

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31
Q

ADH/Vasopressin

A

Conserves water during urine formation

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32
Q

Oxytocin

A

Stimulates uterine contraction during childbirth and milk ejection during breast-feeding

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33
Q

Vasopressin in kidneys

A

Nephrons in kidneys, increase permeability of distal and collecting tubules to H2O

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34
Q

Vasopressin arterioles

A

Throughout body, causes constriction

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35
Q

Hypothalamic-Hypophyseal Portal System

A

System that provides a vascular link to the anterior pituitary from the hypothalamus

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36
Q

Posterior Pituitary Hormones

A

Vasopressin and oxytocin

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37
Q

Anterior Pituitary Hormones

A

TSH
ACTH
FSH
LH
GH
PRL

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38
Q

Thyroid-stimulation hormone (TSH)

A

Stimulates secretion of thyroid hormone

39
Q

Adrenocorticotropic hormone (ACTH)

A

Stimulates secretion of cortisol by adrenal cortex

40
Q

Follicle-stimulating hormone (FSH)

A

Females: growth and development of ovarian follicles and secretion of estrogen by ovaries
Males: sperm production

41
Q

Luteinizing hormone (LH)

A

Females: ovulation and luteinization, ovarian secretion of sex hormones
Males: testosterone secretion

42
Q

Growth hormone (GH)

A

Responsible for regulating overall body growth; intermediary metabolism

43
Q

Prolactin (PRL)

A

enhances breast development and milk production

44
Q

Three pathways in which the hypothalamus and pituitary direct neuroendocrine function

A
  1. HPA
  2. HPG
  3. HPT
45
Q

HPA

A

Hypothalamic-pituitary adrenal axis
- Main stress response system

46
Q

HPG

A

Hypothalamic-pituitary gonadal axis
- Regulate reproduction

47
Q

HPT

A

Hypothalamic-pituitary thyroid axis
- Regulation of metabolism and some stress

48
Q

Tropic hormones target what?

A

Other endocrine glands

49
Q

TRH

A

TRH –> thyroid gland –> thyroid hormone (T3 and T4) –> increased metabolic rate

50
Q

CRH (corticotropin-releasing hormone)

A

CRH –> ACTH –> adrenal cortex –> cortisol
–> metabolic actions; stress response

51
Q

GH-IH

A

GH –> Liver (+) –> IGF-I –> bone and soft tissues –> growth

52
Q

GH-RH

A

GH –> Adipose tissue, muscle, liver (+ or -)
–> metabolic actions

53
Q

Adrenal Glands

A

Embedded above each kidney in a capsule of fat; composed of two endocrine organs

54
Q

What organs are the adrenal glands made of?

A
  1. Adrenal Cortex
  2. Adrenal Medulla
55
Q

Adrenal Cortex

A

Outer portion of adrenal gland that secretes steroid hormones

56
Q

Adrenal Medulla

A

Inner portion of adrenal gland that secretes catecholamine’s (epinephrine and norepinephrine)

57
Q

What layers make up the adrenal cortex?

A

Zona glomerulosa (mineralocorticoids/aldosterone), zona fasciculata, and zona reticularis (both contain glucocorticoids/cortisol and sex hormones dehydroepiandrosterone)

58
Q

Mineralocorticoids

A

Influence mineral balance, specifically Na+ and K+ balance

59
Q

Glucocorticoids

A

Glucose, protein and lipid metabolism, and stress hormone

60
Q

Sex hormones (adrenal cortex)

A

Most abundant physiologically

61
Q

Aldosterone

A

Principal action site on distal and collecting tubules of kidney and regulation of its secretion is largely independent of anterior pituitary control

62
Q

How is aldosterone secretion increased

A
  1. Activation of renin-angiotensin-aldosterone system by factors related to a reduction in Na+ and a fall in blood pressure
  2. Direct stimulation of adrenal cortex by rise in plasma K+ concentration
63
Q

Cortisol

A

Stimulates hepatic gluconeogenesis, inhibits glucose uptake and use by many tissues (but not brain), stimulation protein degradation in many tissues (especially muscle), facilitates lipolysis, plays role in adaptation to stress, can have anti-inflammatory and immunosuppressive effects and pharmacological levels

64
Q

How is cortisol secretion regulated?

A

Negative feedback loop involving hypothalamic CRH and pituitary ACTH

65
Q

Short-term stress response

A

Stress signal to hypothalamus –> along nerve impulses to spinal cord –> preganglionic sympathetic fibers –> adrenal medulla (secretes amino acid based hormones) –> catecholamines
- Increased heart rate
- Increased blood pressure
- Liver converts glycogen to glucose and releases glucose to blood
- Dilation of bronchioles
- Changes in blood flow patterns leading to decreased digestive system activity and reduced urine output
- Increased metabolic rate

66
Q

Long-term stress response response

A

Stress signal to hypothalamus –> CRH release to corticotroph cells of anterior pituitary –>ACTH to target in blood –> adrenal cortex (secretes steroid hormones) –>Mineralocorticoids (retention of Na+ and water by kidneys then increase blood volume and pressure) or Glucocorticoids (proteins and fats converted to glucose or broken down for energy, increased blood glucose, and suppression of immune system)

67
Q

Adrenal medulla function

A
  • Modified part of sympathetic nervous system
  • Primary stimulus for increased adrenomedullary secretion activation of sympathetic nervous system by stress
  • Releases epinephrine and norepinephrine which is secreted into blood by exocytosis of chromaffin granules
68
Q

Epinephrine

A
  • Reinforces sympathetic system in mounting general systemic “fight-or-flight” responses
  • Maintenance of arterial blood pressure
  • Increases blood glucose and blood fatty acids
69
Q

Thyroid Gland

A

Consists of two lobes of endocrine tissue joined in middle by narrow portion of the gland

70
Q

Cells in thyroid gland

A
  1. Follicular cells
  2. C cells
71
Q

Follicular Cells

A

Produce two iodine containing hormones derived from amino acid tyrosine
1. Tetraiodothyronine (T4, thyroxine)
2. Tri-iodothyronine (T3)

72
Q

C Cells

A

Secrete peptide hormone calcitonin

73
Q

Thyroid gland pathway

A

Hypothalamus releases thyrotropin-releasing hormone (TRH) –> thyroid-stimulating hormone (TSH) –> thyroid gland releases T3 and T4 which results in increased metabolism, growth and development, and increased catecholamine effect –> negative feedback leads to more release of TRH and TSH from hypothalamus and anterior pituitary

74
Q

Thyroid hormone regulation

A

Secretion is regulated by negative-feedback system between hypothalamic TRH, anterior pituitary TSH, and thyroid gland T3 and T4; feedback loop maintains thyroid hormones relatively constant

75
Q

Growth Hormone

A

Circadian rhythms, stress and cortisol, and fasting impact GHRH and somatostatin in hypothalamus –> release of growth hormone in anterior pituitary –> can go to liver and other tissues that release insulin-like growth factors and then cartilage growth OR to increase in blood glucose and bone and tissue growth

76
Q

Normal Growth Curve

A

Includes a postnatal growth spurt and pubertal growth spurt

77
Q

Bone growth in embryo

A

Bone starts to replace cartilage

78
Q

Bone growth in a fetus

A

Growth in bone length, medullary cavity development, new centers of bone growth

79
Q

Bone growth in a child

A

Growth in bone width, epiphyseal plate cartilage, spongy bone, new bone formation

80
Q

Types of GH abnormalities

A
  1. GH Deficiency
  2. GH Excess
81
Q

GH Deficiency

A
  • Due to pituitary defect
  • Hyposecretion of GH in child is one cause of dwarfism
  • Deficiency in adults produces relatively few symptoms
82
Q

GH Excess

A
  • Most often caused by tumor of GH-producing cells of anterior pituitary
  • Symptoms depend on age of individual when abnormal secretion begins
83
Q

Types of abnormal secretion

A
  1. Gigantism
  2. Acromegaly
84
Q

Gigantism

A

Caused by overproduction of GH in childhood before epiphyseal plates close

85
Q

Acromegaly

A

Occurs when GH hypersecretion occurs after adolescence

86
Q

Pancreatic Hormones

A

Pancreas has endocrine cells calls Islets of Langerhans; local presence of somatostatin decreases secretion of insulin, glucagon, and somatostatin itself
- B (beta) cells
- A (alpha) cells
- D (delta) cells

87
Q

Beta cells

A

Site of insulin synthesis and secretion

88
Q

Alpha cells

A

Produce glucagon

89
Q

Delta cells

A

Pancreatic site of somatostatin synthesis

90
Q

Insulin

A
  • Anabolic hormone
  • Promotes cellular uptake of glucose, fatty acids, and amino acids and enhances their conversion into glycogen, triglycerides, and proteins –> respectively lowers blood concentration of these small organic molecules
  • Secretion is increased during absorptive state; primary stimulus for secretion is increase in blood glucose concentration
91
Q

Diabetes Mellitus

A
  • Most common endocrine disorder
  • Prominent feature of elevated blood glucose levels; urine acquires sweetness from excess blood glucose that spills into urine
  • Two major types: Type I and Type II
92
Q

Type I Diabetes

A

Characterized by lack of insulin secretion
- None or almost no insulin secretion
- Childhood
- 10-20% of diabetics
- Destruction of beta cells
- Treat with insulin injections, dietary management, and exercise

93
Q

Type II Diabetes

A

Characterized by normal or even increased insulin secretion but reduced sensitivity of insulin’s target cells
- Normal or exceed normal insulin secretion
- Adulthood
- 80-90% of diabetics
- Reduced sensitivity to insulin’s target cells
- Treat with dietary control and weight reduction, exercise, sometimes oral hypoglycemic drugs