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Physiology > Hormones and The Endocrine System (LO #1-35) > Flashcards

Hormones and The Endocrine System (LO #1-35) Flashcards

1
Q

Compare the signaling systems of the Nervous System vs. the Endocrine System.

A

Nervous System: faster
Endocrine System: longer lasting

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2
Q

What do neuronal signals in the Hypothalamus lead to?

A

Hormonal pituitary signals, sense and respond

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3
Q

What type of feedback does a neuronal signal that leads to a hormonal signal in the anterior pituitary an example of?

A

(+ or -) negative feedback

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4
Q

What type of feedback does a neuronal signal that leads to a hormonal signal in the posterior pituitary an example of?

A

positive feedback

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5
Q

In the sympathetic autonomic nervous system, a neuronal signal leads to what?

A

(+)Adrenal Medulla, release of neurohormone (epinephrine)

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6
Q

In the parasympathetic autonomic nervous system, a neuronal signal leads to what?

A

autonomic ganglion, (+ or -) endocrine glad cell, hormone release to effector organs, note Varicosities

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7
Q

Describe Autocrine signaling

A

Autocrine substance acts on the same cell that secreted the substance
path flow- local cell, ISF, autocrine substance, receptor on same cell

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8
Q

Describe Paracrine signaling

A

target calls in close proximity to the site of release of paracrine substance
path flow- local cell, ISF, paracrine substance, receptors on target cell

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9
Q

Describe Neurotransmitter signaling

A

neuron or effector cell in close proximity to site of neurotransmitter release
path flow- nerve cell, electrical signal, neurotransmitter, ionotropic receptors, target cell

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10
Q

What do Endocrine Glands do?

A

take raw materials from the blood and use them to build hormones that go back into the blood

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11
Q

What do Exocrine Glands do?

A

take raw materials from the blood, send them out of the body

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12
Q

Describe Neurohormone Signaling

A

target cell in one or more distance places in the body, path flow- hormone secreting gland cell, hormone, blood vessel, target cell

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13
Q

Describe solubilityPeptide/Protein Hormones.

A

hydrophilic (Lipophobic, water soluble) i.e. not membrane penetrating

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14
Q

Discuss the sequential synthesis and secretion of typical peptide hormones.

A

Synthesis: rough ER, preprohormone shortened to prohormone
Packaging: Golgi, Prohormone folds into hormone
Storage: Secretory Vesicles, mature hormone
Secretion: of hormone and any pro-fragments

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15
Q

What is a preprohormone made of?

A

long string of amino acids

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16
Q

What is a prohormone made out of?

A

short string of amino acids

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17
Q

Describe synthesis of peptides/protein hormones.

A

in ER and Golgi

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18
Q

Describe storage of peptides/protein hormones.

A

packaged into vesicles found in cytosol

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19
Q

Describe major form in plasma of peptides/protein hormones.

A

free/ unbound

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20
Q

Describe receptor location of peptides/protein hormones.

A

plasma membrane

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21
Q

Describe excretion rate of peptides/protein hormones.

A

fast (minutes)

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22
Q

Describe signaling of peptides/protein hormones.

A

second messengers, enzyme activation by receptor, intrinsic enzymatic activity of receptor

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23
Q

Describe solubility of Catecholamine Hormones.

A

hydrophilic, water soluble, non-membrane penetrating

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24
Q

Describe synthesis of Catecholamine Hormones.

A

synthesized from Tyrosine (an amino acid)

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25
Q

Describe major form in plasma of Catecholamine Hormones.

A

free/unbound

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26
Q

Describe receptor location of Catecholamine Hormones.

A

plasma membrane

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27
Q

Describe excretion rate of Catecholamine Hormones.

A

fast (minutes)

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28
Q

Describe signaling of Catecholamine Hormones.

A

second messengers, enzyme activation by receptor, intrinsic enzymatic activity of receptor

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29
Q

Describe solubility of Steroid Hormones.

A

Hydrophobic, lipid soluble

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30
Q

Describe synthesis of Steroid Hormones.

A

synthesized from cholesterol, synthesis in adrenal cortex and gonads

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31
Q

What are the properties of Catecholamine Hormones similar to?

A

Peptide/protein hormones

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32
Q

Describe major form in plasma of Steroid Hormones.

A

protein bound

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33
Q

Describe receptor location of Steroid Hormones.

A

Intracellular

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34
Q

Describe excretion rate of Steroids Hormones

A

slow (hours to days)

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35
Q

Describe signaling of Steroids Hormones

A

intracellular receptors directly alter gene transcription

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36
Q

Discuss the synthesis and secretion of steroid hormones in the adrenal cortex.

A

-happens in adrenal gland, produces cortisol, aldosterone, and DHEA
-cholesterol is source material

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37
Q

Discuss the synthesis and secretion of steroid hormones in the gonads.

A

-happens in gonads, produces testosterone, progesterone, and estrogen

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38
Q

What enzyme is used in the production of testosterone?

A

5-alpha reductase

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39
Q

What enzyme is used in the production of estrogen?

A

Aromatase

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40
Q

Describe the major form in plasma of Thyroid Hormone.

A

protein bound

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41
Q

Describe the location of receptors for Thyroid Hormone.

A

intracellular

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42
Q

Describe the most common signaling for Thyroid Hormone.

A

intracellular receptors directly alter gene transcription

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43
Q

Describe the rate of excretion for Thyroid Hormone.

A

slow (hours or days)

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44
Q

What is Thyroid Hormone? What are the two types?

A

an amine, T4 and T3

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45
Q

Describe the synthesis for Thyroid Hormone.

A

derived from tyrosine, not cholesterol

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46
Q

Describe the solubility for Thyroid Hormone.

A

very hydrophobic, lipid soluble

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47
Q

Discuss the possible fates of a hormone after secretion.

A

After an endocrine cell produces a hormone and the hormone enters the bloodstream, the hormone can
1. Be excreted in urine and feces
2. Be inactivated by metabolism
3. Be activated by metabolism
4. Bind to a receptor on target cells, and produce a cellular response (3 can lead to 4)

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48
Q

Describe the location of a hydrophobic hormone receptor.

A

intracellular

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49
Q

What happens in general when a hydrophobic hormone binds to a receptor?

A
  1. Messenger diffuses out of capillaries from plasma to interstitial fluid
  2. messenger diffuses across lipid bilayers of the plasma membrane and nuclear envelope to enter the nucleus and bind to its receptor
  3. The activated receptor complex then functions in the nucleus as a transcription factor, defined as a regulatory protein that directly influences gene transcription
  4. Hormone receptor complex binds to DNA at a regulatory region of a gene, an event that typically increases the rate of the gene’s transcription into mRNA
  5. The mRNA molecules move out of the nucleus to direct the synthesis, on ribosomes, of the protein gene encodes
  6. Protein synthesis
  7. Cell response
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50
Q

Describe the receptor locations of hydrophilic hormones.

A

extracellular surface of the target cell

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51
Q

Describe what happens in general when a hydrophilic hormone binds to a receptor.

A

the receptors trigger one or more signal transduction pathways for plasma membrane receptors, which directly influences G proteins coupled in the plasma membrane to effector proteins (ion channels and enzymes) that generate second messengers
eg. cAMP, Ca2+, IP3
PKA and PLC-PKC cascades

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52
Q

List and describe five important characteristics of hormone receptors

A
  1. They determine which tissues respond to an endocrine “broadcast”
  2. High sensitivity
  3. Huge signal amplification (because of signal transduction mechanisms)
  4. Hormone levels influence expression of their own receptors; up-regulation and down-reglation
  5. Hormones can have a permissive effect on expression of other hormone’s receptors
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53
Q

What is the difference between up-regulation and down-regulation?

A

up-regulation occurs when there is a continued low concentration of hormones, and it increases the number of receptors

down-regulation occurs when there is a continued high concentration of hormones, and it decreases the number of receptors

54
Q

Use Thyroid Hormone as an example to describe what is means for a hormone to be permissive of another hormone.

A

Thyroid hormone is permissive of epinephrine effects because thyroid hormone increases the number of epinephrine receptors on target cells

Thyroid hormone goes to nucleus, bind to receptor, induces protein synthesis, some of which are epinephrine receptors

55
Q

What is the difference between hyper-secretion and hypo-secretion?

A

hyper-secretion: too much hormone pathology wherein negative feedback is ignored

hypo-secretion: too little hormone, often glandular destruction or loss of key regulators

eg for both: tumors and auto-immunity

56
Q

What is the difference between hyper-responsiveness and hypo-responsiveness?

A

hyper-responsiveness: receptor up-regulation or altered functions within the second messenger cascades

hypo-responsiveness: receptor down regulation or altered functions within the second messenger cascade

57
Q

Where do a large portion of endocrine signals begin?

A

Hypothalamus

58
Q

What does the hypothalamus regulate?

A

Activity of cells in the anterior pituitary gland and neurohormone release from the posterior lobe of the pituitary gland

59
Q

Which lobe of the pituitary gland receives tropic hormones from the hypothalamus via portal vessels?

A

anterior lobe

60
Q

What is the physiological response of the anterior lobe after receiving tropic hormones?

A

increase or decrease in secretions

61
Q

Do you know the parts of the hypothalamus and pituitary gland? (LO 14)

A

yes

62
Q

What is the posterior lobe of the pituitary gland composed of?

A

axon terminals of neurons that begin in the hypothalamus

63
Q

What is the relationship between the Hypothalamus and the Posterior Pituitary gland?

A

Action potentials propagate from hypothalamus to posterior lobe terminals and trigger exocytosis of neurohormones

64
Q

List the peptides released from the Posterior Pituitary

A
  1. Anti-Diuretic Hormone (ADH, aka vasopressin)
  2. Oxytocin
65
Q

What is the role of ADH released from the Posterior Pituitary?

A

water retention via kidney, constriction of smooth muscle in blood vessels

66
Q

What is the role of Oxytocin released from the Posterior Pituitary?

A

contraction of uterine smooth muscle during birth, milk secretion from breast tissue upon suckling, bonding behaviors in both females and males (also parental)

67
Q

Describe the hormone exchange that occurs in the blood of the anterior pituitary

A

Hypophysiotropic hormone enters goes from the blood stream into anterior pituitary gland cells, then anterior pituitary hormone enters the bloodstream and go out to entire body via venous circulation

68
Q

Describe Tropic Action.

A

to affect secretion, can be positive or negative

69
Q

Describe Trophic Action.

A

to promote the growth and development of targets

70
Q

Describe a generic three gland cascade

A

Stimulus
Hypothalamus
Hormone 1 (hypophysiotropic)
Anterior Pituitary
Hormone 2 (trophic)
Gland 3
Hormone 3
Target Cell

71
Q

Describe Long Loop negative feedback

A

affects anterior pit and hypothalamus

72
Q

Describe Short Loop negative feedback

A

affects hypothalamus

73
Q

List the Hypothalamus Hypophysiotropic Hormones

A

GnRH, GHRH, SST, TRH, DA, CRH

74
Q

List the Anterior Pituitary Hypophysiotropic Hormones

A

FSH, LH, Growth Hormone, TSH, Prolactin, ACTH

75
Q

What does Corticotropin-releasing hormone (CRH) do?

A

stimulates secretion of ACTH

76
Q

What does Thyrotropin-releasing hormone (TRH) do?

A

stimulate secretion of TSH

77
Q

What does Growth Hormone Releasing Hormone (GHRH) do?

A

stimulates secretion of GH

78
Q

What does Somatostatin(SST) do ?

A

inhibits secretion of GH

79
Q

What does Gonadotropin-releasing hormone (GnRH) do?

A

stimulates secretion of LH and FSH

80
Q

What does Dopamine(DA) do?

A

Inhibits secretion of prolactin

81
Q

Other than dopamine, what chemical class are all hypophysiotropic hormones? What about dopamine?

A

peptides, catecholamine

82
Q

What cell type does FSH and LH affect?

A

gonadotrophs (gonads)
-germ cell development
-secrete hormones

83
Q

What cell type does growth hormone affect?

A

somatotrophs
-largest group
- liver, tissues and organs
-protein synthesis, carbohydrate and lipid matabolism

84
Q

What cell type does TSH affect?

A

thyrotrophs (thyroid)
-secretes T3 and T4

85
Q

What cell type does Prolactin affect?

A

lactotrophs (breasts)
-breast development and milk production in women

86
Q

What cell type does ACTH affect?

A

corticotrophs (adrenal cortex)
-secretes cortisol

87
Q

Describe the histology of the Thyroid Gland (LO 19)

A

composed primarily of colloid-filled spheres enclosed by a single layer of follicular cells

88
Q

Describe Thyroid Hormone in the thyroid gland.

A
  1. Thyroid Hormone is conjugated to thyroglobulin, a protein that cannot pass across membranes and is stored in colloid
  2. Thyroid hormone is stored until stimulated to be secreted
  3. Thyroid hormone is transported in the blood bound to carrier proteins
  4. Thyroid hormone is lipophilic amine hormone, and thus binds to receptors located inside the target cell
89
Q

Describe the structure of thyroid hormone, distinguishing between T3 and T4

A

follicles trap iodide for the synthesis of thyroid hormones
T4 (thyroxine)
-90% of secretion
-storage pool in blood
-converted to T3 in target cells
T3(triiodothyronine)
-most active, potent form

90
Q

Describe the steps of thyroid hormone synthesis, storage, and regulated secretion in 7 steps. (LO 21)

A
  1. Iodide is co-transported w/ Na+
  2. Diffusion
  3. Iodide is transported to colloid, oxidized, and attached to rings of tyrosines on thyroglobulin
  4. The iodinated ring of the MIT or DIT is added to a DIT at another spot
  5. Endocytosis of Thyroglobulin containing T3 and T4 molecules
  6. Lysosomal enzymes release T3 and T4 from TG
  7. T3 and T4 secretion
91
Q

What starts the cascade of thyroid hormone synthesis?

A

TSH binding to receptor

92
Q

Where do steps 2, 5, 6, and 7 of thyroid hormone synthesis occur?

A

follicle cell

93
Q

Where do steps 3 and 4 of thyroid hormone synthesis occur?

A

lumen of the follicle (colloid)

94
Q

Describe the 3-gland cascade that depicts the regulated secretion of thyroid hormone

A

neural inputs
hypothalamus, TRH secretion
plasma TRH increases
anterior pituitary, TSH secretion
plasma TSH increases
thyroid gland, T3 and T4 secretion
plasma thyroid hormone increases

TRH, TSH, T3 and T4

95
Q

List and describe the actions of Thyroid Hormone

A
  1. Affects virtually every cell, increase gene transcription and protein synthesis (especially metabolism-related gene products)
  2. Controls basal metabolic rate (BMR) and thus body temperature (rate at which cells burn fuel to maintain basic life functions), mainly increased by Na+/K+ ATPase
  3. Permissive of beta-adrenergic receptor (catecholamine) expression (symp NE and Epi)
  4. Essential fro fetal CNS development and function, equally important for proper adult nervous system function
  5. Permissive for overall growth and development
96
Q

Describe Hypothyroidism.

A

causes: damage to thyroid gland, lack of iodide in diet, auto-immune thyroiditis (Hashimotos)

Goiter occurs if cause is iodine deficiency

symptoms: low BMR, cold intolerance, fatigue, inappropriate weight gain, weak pulse, decreased alertness and cognitive function

no T3 and T4 secretion, no negative feedback occurs

trophic effects

97
Q

Describe Hyperthyroidism.

A

causes: auto-immune stimulation of TSH receptors (Grave’s disease), anti-bodies mimic TSH hormone, stimulate the receptor

symptoms: high BMR, heat intolerance, nervous/irritability, insomnia, inappropriate weight loss, constant fight or flight state, exopthalmos

increase in T3 and T4 secretion, too much negative feedback

trophic effects

98
Q

Name the two parts of the adrenal glands.

A

Medulla (inner) and Cortex (outer)

99
Q

What defines the layers of the adrenal glands?

A

preferential presence of enzymes

100
Q

Name the three layers of the cortex and what they are made of

A

zona glomerulosa - aldosterone

zona fasciculata - cortisol and small amount of androgens

zona reticularis - androgens (DHEA) and small amount of cortisol

101
Q

What is the medulla made up of?

A

epinephrine and norepinephrine

102
Q

What type of hormones does the adrenal medulla secrete?

A

amine hormones (phillic catechols)

103
Q

What is the adrenal medulla considered?

A

a modified sympathetic ganglion that does not give rise to postganglionic fibers

104
Q

Name the three adrenergic receptors and their location

A

Alpha one- smooth muscle (contraction, constrict)
Beta one- cardiac muscle
Beta two - smooth muscle (relaxation, dilation)

105
Q

Describe the 3-gland cascade for the regulated secretion of cortisol.

A

neural inputs
hypothalamus, CRH secretion
plasma CRH increases
anterior pituitary, ACTH secretion (corticotroph cells)
plasma ACTH increases
adrenal cortex, cortisol secretion (zona fasciculata)
plasma cortisol increases
target cells

106
Q

What increases during distress?

A

cortisol

107
Q

What increases during eustress?

A

epinephrine

108
Q

Name the functions of the Adrenal Catecholamines in stress

A

Epi reinforces, supports sympathetic nervous system effects initiated by NorEpi during fight or flight stress response:
-dilates respiratory airways and increases ventilation
-reduces digestive activity
-inhibits bladder emptying
-dilates blood vessels to heart skeletal muscles
-mobilizes glucose (from liver), triglyceride (from adipose)
-dilates pupils and increases cardiac function
-increases CNS alertness

109
Q

Where does the regulation of cortisol secretion occur?

A

Zona Fasciculata

110
Q

Describe the functions of cortisol during Basal Levels

A
  1. Metabolic effects: liver glucose production (for neurons) between meals (provides substrates and maintain enzymes involved in metabolic homeostasis)
  2. Permissive of adrenergic receptors in the cardiovascular system (maintain adequate mean arterial blood pressure)
  3. Anti-inflammatory/ anti-immune (prevent hyper-response), cortisone
  4. Fetal/neonatal development of brain, intestines, lungs, glands (production of surfactant in last months of gestation)
111
Q

Describe the functions of cortisol during Stress Levels

A
  1. Metabolic effects (glucose sparing), mobilize glucose, fatty acids, amino acids for fuel and tissue repair
  2. Bone resorption (reabsorbs parts of long bone), Ca2+ mobilization, repair bone breaks
  3. Support sympathetic responses (fight, flight) keep MAP up
  4. Stimulates erythropoietin (replace RBCs) bleeding wound
  5. Anti-inflammatory/ Immunosuppression (helps to prevent rejection of transplanted organs)
  6. Psychological/Analgesic, cortisol elevates mood, endorphins co-released w/ ACTH; inhibit pain
  7. Inhibition of non-essential functions: reproduction/growth
112
Q

What are symptoms of chronic stress and what causes them?

A

weak bones, high BP due to too much cortisol

113
Q

Describe Primary Adrenal Insufficiency

A

aka Addison’s disease, hypo-secretion of cortisol
no cortisol, no negative feedback
issue in adrenal cortex where cortisol is secreted
causes: destructive tumors, infection, auto-immune destruction
symptoms: hypotension, hypoglycemia, high plasma ACTH

114
Q

Describe Secondary Adrenal In sufficiency

A

hypo-secretion of cortisol
loss or low ACTH in plasma (anterior pituitary and tropic hormone)
symptoms are same as primary

115
Q

Describe the difference between Cushing’s Syndrome and Cushing’s Disease

A

Hyper-secreting tumor, tumors ignore negative feedback
Syndrome is primary, takes place in adrenal cortex
Disease is secondary, takes place in anterior pituitary
symptoms: osteoporosis, hyperglycemia, high bp, immunosepression, obesity of trunk and face and yet wasting of arms and legs

116
Q

How do long bones actually elongate?

A

at growth plates next to their epiphysis where rapid mitosis and differentiation occur under the influence of both local and circulating hormones.

117
Q

What two hormones are involved in the elongation of bones?

A

IGF-1 and GH

118
Q

When do growth plates fuse?

A

After prolonged exposure to sex steroids (estrogen and testosterone), disappear after puberty

119
Q

What two things are found within the marrow cavity?

A

EPO from kidney, RBCs

120
Q

Describe what occurs in the epiphyseal plate

A

hyperplasia - chondrocytes undergoing cell division
hypertrophy - older chondrocytes enlarging

121
Q

Describe what occurs in the shaft

A

osteoblasts covert cartilage into bones

122
Q

How does Growth Hormone influence growth?

A

stimulates protein synthesis

123
Q

How does Insulin influence growth?

A

“builder”

124
Q

How does Thyroid Hormone influence growth?

A

permissive for growth hormone secretion, permissive for development of central nervous system

125
Q

How does estradiol influence growth?

A

stimulates secretion of growth hormone at puberty, causes eventually epiphyseal closure

126
Q

How does cortisol influence growth?

A

inhibits growth, stimulates protein catabolism

127
Q

What are the major effects of growth hormone?

A

promotes growth, stimulates protein synthesis, anti-insulin effects

128
Q

Describe the 3 gland cascade for the regulated secretion of growth hormone and IGF-1

A

stimulus: excersize, stress, fasting, low plasma glucose, sleep
Hypothalamus: GHRH secretion and SST secretion(inhib)
Anterior Pit: GH secretion
Liver and other cells: IGF-1 secretion

IGF-1 : neg feedback on GHRH and GH, pos feedback on SS
GH: pos feedback on IGF-1 and SS, neg feedback on GHRH
SS: neg feedback on GH
GHRH: pos feedback on GH

Target cells : hypertrophy and hyperplasia

129
Q

Describe short stature

A

GH goes down, so IGF-1 goes down
insensitive GH receptors
lack of IGF-1 secretion (GH okay)
Insensitive IGF-1 receptors

130
Q

Compare acromegaly and gigantism

A

both caused by tumors of the anterior pituitary that hyper-secrete GH

acromegaly- too much GH after the epiphyseal plates close (thick bones)

gigantism- too much GH before epiphyseal plates close

131
Q

Where is capillary bed #1?

A

median eminence

Physiology (9 decks)

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