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BIO 203 Vertebrate Anatomy Physio > The Endocrine System > Flashcards

The Endocrine System Flashcards

1
Q

intercellular communication

A

-preserves homeostasis
-mostly done through chemical messages

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2
Q

distant communication

A

is coordinated by endocrine and nervous systems

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3
Q

nervous system is fast

A

specific and short duration

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4
Q

endocrine system is slower

A

releases hormones into bloodstream that bind to target cells, long duration

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5
Q

nervous and endocrine systems comparison

A

-both rely on the release of chemicals that bind to specific receptors on target cells
-both share chemical messengers
-both are regulated by negative feedback mechanisms
-both coordinate and regulate activities of other cells, tissues, organs, and systems to maintain homeostasis

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6
Q

chemical messengers for nervous and endocrine systems

A

-Epinephrine (E) and norepinephrine (NE), hormones released from the adrenal medulla
-NE, a neurotransmitter when released in synapses

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7
Q

the endocrine system

A

-includes all endocrine cells and tissues
-cells are glandular and secretory
-secretions enter the ECF
-cytokines are local chemical messengers
-hormones are chemical messengers secreted into the blood and transported to target cells

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8
Q

peptide hormones

A

-largest group
-includes ADH, oxytocin, hypothalamic, pituitary, pancreatic hormones

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9
Q

lipids derivatives

A

-most derived from cholesterol
-steroid hormones released by reproductive organs and adrenal cortex
-for example, testosterone, estrogen

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10
Q

mechanisms of hormonal action

A

hormones alter operations of target cells
-changes identities, activities, locations, or quantities of structural proteins and enzymes
-sensitivity of target cell to hormones depends on specific receptors
-receptors are located either on plasma membrane or inside the cell

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11
Q

hormonal action at the plasma membrane

A

receptors on plasma membrane
-E, NE, and peptide hormones are not lipid soluble
-cannot diffuse through the plasma membrane
-must use a receptor on outside of membrane
-effect is not direct; they are first messengers that activate second messengers in the cytoplasm
-action is linked by G protein, an enzyme complex

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12
Q

cyclic-AMP second messenger system

A

cyclic AMP, or cAMP
-first messenger activates a G protein
-which activates enzyme adenylate cyclase
-which converts ATP to second messenger, cAMP
-which activates kinase enzymes inside cell
-which phosphorylates another molecule
-enzyme cascade
-produces amplification of signal

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13
Q

intracellular receptors

A

receptors inside cytoplasm or nucleus
-for thyroid and steroid hormones, lipid soluble
-forms hormone-receptor complex
-activates or inactivates specific genes
-alters rate of mRNA transcription
-changes structure or function of cell

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14
Q

hormone secretion and distribution

A

-rapidly enter blood and distributed throughout body
-freely circulating hormones are short-lived and inactivated when:
1. They diffuse to target cells and bind to receptors
2. They are absorbed and broken down in liver and kidney
3. They are broken down by enzymes in plasma or interstitial fluid
-hormones bound to transport proteins stay in circulation longer (steroid and thyroid hormones)
-each hormone has an equilibrium between bound and free forms

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15
Q

the hypothalamus and endocrine control

A

coordinating centers in hypothalamus regulate nervous and endocrine systems

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16
Q

the hypothalamus

A
  1. Acts as an endocrine gland, synthesizing ADH and oxytocin
  2. Secretes releasing and inhibiting regulatory hormones to control anterior pituitary secretions
  3. Contains ANS centers that control adrenal medullae through sympathetic innervation
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17
Q

the pituitary gland

A

-Also called the hypophysis
-Hangs from hypothalamus by infundibulum
-Anterior and posterior have very different structure
-Secretes nine hormones
-All are unique peptides or small proteins
-All use cAMP second messenger mechanism

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18
Q

the seven anterior lobe hormones

A
  1. Thyroid-stimulating hormone (TSH)
  2. Adrenocorticotropic hormone (ACTH)
  3. Follicle-stimulating hormone (FSH)
  4. Luteinizing hormone (LH)
  5. Prolactin (PRL) (milk production in mammary gland)
  6. Growth hormone (GH)
  7. Melanocyte-stimulating hormone (MSH) (triggers production of melanin)
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19
Q

Prolactin (PRL)

A

milk production in mammary gland

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20
Q

Melanocyte-stimulating hormone (MSH)

A

triggers production of melanin

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21
Q

thyroid-stimulating hormone also called thyrotropin

A

-Released in response to thyrotropin-releasing hormone (TRH) from hypothalamus
-Triggers release of thyroid hormones from thyroid glands
-Increases in thyroid hormones cause decrease in TRH and TSH secretion

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22
Q

adrenocorticotropic hormone also called corticotropin

A

-Stimulates secretion of steroid hormones, called glucocorticoids, from adrenal cortex
-Corticotropin-releasing hormone (CRH) from the hypothalamus triggers release of ACTH
-Increases in glucocorticoids feed back to inhibit ACTH and CRH secretion

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23
Q

the gonadotropins, or sex hormones, are triggered by

A

gonadotropin-releasing hormone (GnRH) from hypothalamus

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24
Q

Follicle-stimulating hormone (FSH)

A

-promotes follicle (and egg) development females
-promotes sperm production in males

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25
Q

luteinizing hormone (LH)

A

-induces ovulation and secretion of progestins in females
stimulates production of androgens such as testosterone in males

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26
Q

growth hormone

A

also called human growth hormone (hGH) and somatotropin
-stimulates cell growth and replication of all cells, but especially skeletal muscle and chondrocytes

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27
Q

the two posterior lobe hormones

A

hormones diffuse down axons of hypothalamic neurons that extends into posterior lobe, then into capillaries
1. antidiuretic hormones (ADH)
2. oxytocin (OXT)

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28
Q

antidiuretic hormone also called vasopressin

A

-stimulated by increase in ECF osmolarity or decrease in blood volume and pressure
-primary target is kidney to decrease water loss
-triggers vasoconstriction to increase blood pressure

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29
Q

oxytocin

A

-in women stimulates contraction of uterine muscles during labor and delivery
-also stimulates contraction of cells surrounding milk secretory cells in mammary glands
-appears to play unclear role in sexual arousal

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30
Q

the thyroid gland

A

-found anterior to trachea and inferior to thyroid cartilage
-has two lobes connected by narrow isthmus
-contains many spherical thyroid follicles
-defined by simple cuboidal epithelium
-filled with viscous colloid with many proteins and thyroid hormones moleclues

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31
Q

the thyroid follicles

A

-follicular cells make thyroid hormones that are then stored in colloid
-TSH causes release of thyroid hormones
-majority are transported by plasma proteins
-dervied from amino acid tyrosine, and iodine
-thyroxine (T4 or tetraiodothyronine) has four atoms of iodine
-triiodothyronine (T3) has three iodine and is more potent

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32
Q

the effects of thyroid hormones

A

-activate nearly every cell in body
-increase rate of ATP production in mitochondria
-activate genes coding for enzyme synthesis
-enzymes increase rate of metabolism
-calorigenic effect is when cell uses more energy, measured in calories, and heat is produced

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33
Q

the c cells of the thyroid gland also called parafollicular cells, are found between follicles

A

produce calcitonin (CT)
-stimulated by increases in plasma Ca2+
-inhibits osteoclasts in bone
-stimulates calcium excretion by kidneys
-essential for normal bone growth in children and last trimester of pregnancy

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34
Q

calcium imbalances

A

hypercalcemia and hypocalemia

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35
Q

hypercalcemia causes

A

-decreased sodium permeability of excitable membranes
-results in less responsive muscles and nerves

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36
Q

hypocalcemia causes

A

-increased sodium permeability
-highly excitable, spasmodic muscles and nerves
-parathyroid glands prevent hypocalcemia

37
Q

the parathyroid glands

A

-paired, small glands embedded in posterior surface of thyroid
-chief cells produce parathyroid hormone (PTH)

38
Q

chief cells produce parathyroid hormone (PTH)

A

-stimulated by decrease in plasma Ca2+
-activates osteoclasts in bone
-reduces calcium excretion by kidney
-stimulates kidney to secrete calcitriol, which increases Ca2+ absorption in digestive tract

39
Q

the adrenal gland also called the suprarenal gland

A

-yellow, pyramid-shaped
-sits on superior border of each kidney
-two portions
1. Adrenal cortex
-outer part
2. Adrenal medulla
-inner part

40
Q

the adrenal cortex

A

-contains high levels of cholesterol and fatty acids
-produces more than 24 steroid hormones called corticosteroids

41
Q

corticosteroids

A

-are essential for metabolic functions
-transported in plasma bound to proteins
-three zones of cortex produce three types
1. Mineralcorticoids
2. Glucocorticoids
3. Androgens

42
Q

mineralocorticoids also called MCs

A

-produced by outer zone
-affect electrolyte balance in body fluids
-aldosterone - major MC

43
Q

aldosterone - major MC

A

-secreted in response to low plasma Na=, low BP, high plasma K+, or presence of angiotensin II
-triggers reabsorption of sodium ions in kidney, sweat glands, salivary glands, and pancreas
-secondarily triggers water reabsorption through osmosis

44
Q

glucocorticoids also called GCs

A

-produced mostly by middle zone
-affect glucose metabolism
-most important are cortisol, corticosterone, and cortisone

45
Q

most important are cortisol, corticosterone, and cortisone

A

-secreted in response to ACTH
-increase rates of glycolysis and glycogenesis, resulting in increase in blood glucose levels
-also act as anti-inflammatory

46
Q

androgens

A

-produced by inner zones in both males and females
-some converted to estrogens in plasma
-in normal amounts do not affect sexual characteristics
-function remains unclear

47
Q

the adrenal medulla

A

-highly vascular, containing cells similar to sympathetic ganglia
-innervated by preganglionic sympathetic fibers
-epinephrine (E, or adrenaline) is 80 percent
-norepinephrine (NE, or noradrenaline) is 20 percent
-triggers metabolic changes to increase availability of energy molecules
-supports and prolongs overall sympathetic response

48
Q

the pineal gland

A

-located on posterior portion of roof of third ventricle
-contains neurons, glial cells, and secretory cells that produce melatonin
-rate of secretion affected by light and day–night cycles
-may influence timing of sexual maturation
-plays role in maintaining circadian rhythms (day–night cycles)
-linked to pineal or parietal eye in some organisms (fish, amphibians, reptiles)

49
Q

the endocrine pancreas

A

-pancreas lies between stomach and proximal small intestine
-contains both exocrine and endocrine cells
-endocrine cells located in pancreatic islets

50
Q

endocrine cells located in pancreatic islets also called islets of Langerhans, contain:

A

-alpha cells that secrete hormone glucagon
-beta cells that secrete hormone insulin

51
Q

pancreatic regulation of blood glucose

A

-increases in blood glucose levels (BGL) activate beta cells to release more insulin
-decreases in blood glucose levels activate alpha cells to release more glucagon
-secretion of hormones is independent of direct neural stimulus
-indirectly affected by ANS activity and any hormones that also influences BGL
-for example, cortisol and thyroid hormones

52
Q

increases in blood glucose levels (BGL) activate beta cells to release more insulin

A

-stimulates glucose uptake by cells
-result is lower BGL

53
Q

decreases in blood glucose levels activate alpha cells to release more glucagon

A

mobilizes energy reserves
-glycogen in liver and muscles broken down to glucose
-adipose tissue releases fatty acids
-proteins broken down to convert to glucose in the liver
-result is higher BGL

54
Q

diabetes mellitus

A

either hyposecretion of insulin or decreased sensitivity of insulin receptors

55
Q

diabetes mellitus symptoms

A

hyperglycemia, glycosuria, polyuria, and polydipsia

56
Q

what are the two forms of diabetes mellitus

A

type I and type II

57
Q

type I – insulin-dependent diabetes mellitus

A

-pancreas does not produce insulin
-immune cells destroy the pancreatic islets

58
Q

type II –non-insulin-dependent diabetes mellitus

A

-normal or elevated amounts of insulin are present in the blood
-receptors on the cells do not respond to insulin

59
Q

the intestines

A

-secrets local hormones that coordinate digestive activities
-major control over rate of digestive processes
-can be influenced by ANS

60
Q

the kidneys has

A

calcitriol, erythropoietin, renin

61
Q

calcitriol

A

stimulated by PTH, derived from vitamin D3, increases absorption of calcium and phosphate ions from gut

62
Q

erythropoietin

A

stimulated by kidney hypoxia, causes RBC production

63
Q

renin

A

an enzyme that triggers hormonal chain reaction to increase BP, blood volume

64
Q

the heart

A

atrial natriuretic peptide (ANP)
-promotes loss of sodium, and therefore water
-inhibits renin release
-results in decrease n BP and blood volume

65
Q

the thymus is located

A

deep to sternum in mediastinum

66
Q

the thymus

A

very active in early childhood, atrophies in adults
secretes thymosins
-aid in development and maintenance of immune defenses

67
Q

the gonads: the testes

A

-in males, interstitial cells produce androgens
-most important is testosterone

68
Q

testosterone

A

-promotes sperm production
-maintains secretory glands of reproductive tract
-determines secondary sex characteristics
-stimulates protein synthesis
-sperm production effect balanced by inhibin

69
Q

the gonads: the ovaries

A

-in females, the ova are surrounded by follicles
-FSH triggers follicular cells to produce: estrogens and inhibin
-once follicles releases ovum (ovulation) the corpus luteum is formed from follicular cells
-releases progesterone
-all gonadal hormones regulated by hormones of the anterior pituitary

70
Q

estrogens

A

support maturation of ova and growth of uterine lining

71
Q

inhibin

A

provides negative feedback to FSH

72
Q

releases progesterone

A

-accelerates fertilized egg movement through uterine tube
-prepares uterus for arrival of developing embryo

73
Q

adipose tissue - produces leptin

A

-provided negative feedback control of appetite
-binds to neurons in hypothalamus to trigger satiation (fullness) and suppression of appetite
-must be present for normal GnRH and gonadotropin synthesis
-low body fate can result in late puberty and cessation of menstrual cycles
-increase in body fat can increase fertility

74
Q

hormonal interactions

A

ECF contains hormones that may have the same target, resulting in four possiblities
-antagonistic, synergistic, permissive, and intefrative effects

75
Q

hormonal interactions

A

ECF contains hormones that may have the same target, resulting in four possiblities
-antagonistic, synergistic, permissive, and integrative effects

76
Q

antagonistic effects

A

opposing receptors

77
Q

synergistic effects

A

net result of two is greater that the sum of their individual effects

78
Q

permissive effects

A

need for one hormones to be present for another to work

79
Q

integrative effects

A

coordinate diverse activities

80
Q

six key hormones required for normal growth

A

GH, thyroid hormones, insulin, PTH, calcitriol(,) same at PTH, reproductive hormones

81
Q

GH

A

-undersecretion causes dwarfism
-oversecretion causes gigantism

82
Q

thyroid hormones

A

required for normal nervous system development

83
Q

insulin

A

required for energy supply to growing cells

84
Q

PTH

A

promotes calcium availability for normal bone growth

85
Q

calcitriol, same as PTH

A

lack of PTH and calcitriol can result in rickets

86
Q

reproductive hormones

A

can affect activity of osteoblasts and influence secondary sex characteristic development

87
Q

stress is triggered by

A

-physical injury or disease
-emotional responses: anxiety or depression
-environmental conditions: extreme cold or heat
-metabolic conditions: acute starvation

88
Q

stress triggers

A

-the general adaptation syndrome (GAS)
-also called the stress response

89
Q

hormones and aging

A

-usually most hormones remain the same throughout adulthood
-exceptions are the reproductive hormones
-changes to target organ receptors more likely to occur through reduced sensitivity

BIO 203 Vertebrate Anatomy Physio (8 decks)

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