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Endocrine System > Physiology > Flashcards

Physiology Flashcards

1
Q

What are the 3 classes of Hormones based on their chemical actions?

A
  1. Amino Acid Derivatives
  2. Peptides

3.Steroids

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2
Q

Fill in the blanks. “Steroids are derived from _______.”

A

Cholesterol

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3
Q

What are the 2 classes of Hormones based on their molecular mechanism?

A

1.Cell surface
2. Intra-cellular

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4
Q

Where is Epinephrine secreted from?

A

The Adrenal Medulla

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5
Q

Give examples of hormones that act on the cell surface?

A

Epinephrine , Glucagon ,
Insulin

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6
Q

Fill in the blanks . “ Thyroid hormones are ________.”

A

Amino acid derivatives

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7
Q

Where is the site for the Primary action of epinephrine?

A

Muscles

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8
Q

Fill in the blanks. “ Epinephrine stimulates hydrolysis of _________ to _________ in adipocytes .”

A

It stimulates the hydrolysis of Triglycerides to Free Fatty Acids

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9
Q

Which hormone is produced in a hypoglycaemic state?

A

Hyperglycaemic glycogenolytic hormone.

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10
Q

What is the inactive form of Pancreatic polypeptide hormone?

A

Proglucagon

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11
Q

True or False? Glucagon has no effect on muscle.

A

TRUE!!

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12
Q

Fill in the blanks. “ Glucagon acts via ______.”

A

Andenyl cyclase

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13
Q

Give examples of hormones that act intracellularly.

A

Lipid in nature ( steroids) , Thyroid Hormones

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14
Q

Into what structures does the Hypothalamus release secretions into?

A

The median eminence,Posterior pituitary & Spinal cord

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15
Q

Which Hypothalamic nuclei results in the secretion of Anti-diuretic hormone & Oxytocin?

A

Supra-optic nuclei

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16
Q

What is the function of the Supra-chiasmatic nuclei?

A

It controls the circadian rhythm regulation & pineal gland function

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17
Q

Which Hypothalamic Nuclei is responsible for the secretion of dopamine , growth - hormone releasing hormone & Gonadotrophin ?

A

Arcuate nuclei

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18
Q

Fill in the blanks. “The Anterior Hypothalamic Nuclei mediates ________________ via ____________ and destruction leads to ___________.”

A

The Anterior Hypothalamic nuclei mediates HEAT DISSIPATION via PARASYMPATHETICS and destruction leads to HYPERTHERMIA.

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19
Q

Fill in the blanks .” The Posterior Hypothalamic Nuclei mediates ___________ via __________ and destruction leads to ___________.”

A

The Posterior Hypothalamic nuclei mediates HEAT CONSERVATION via SYMPATHETICS and destruction leads to HYPOTHERMIA.

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20
Q

What substances are secreted by the Paraventricular hypothalamic nuclei?

A

ADH
Corticotropin - releasing hormone
Oxytocin & Thyrotropin releasing hormone

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21
Q

True or False? The lateral hypothalamic nuclei mediates satiety ,destruction leads to Hyperphagia and it is stimulated by Leptin.

A

FALSE!! The Ventromedial hypothalamic nuclei does this.

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22
Q

Fill in the blanks.” The lateral hypothalamic nuclei mediates __________, destruction leads to ________ and it is _______ by Leptin .

A

The lateral hypothalamic nuclei mediates HUNGER , destruction leads to ANNOREXIA and it is INHIBITED by Leptin.

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23
Q

Fill in the blanks. “ Neurosecretory neurons are _______, _______ secretory cells.

A

Glandular, Unmyelinated

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24
Q

Where are Magnocellular (large) endocrine neurons located?

A

They are located in the paraventricular & supraoptic nuclei.

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25
Q

Where are Parvicellular (small) neurosecretory neurons located?

A
  • The medial basal region,
  • The arcuate& tuberal nuclei
  • The periventricular region * The preoptic, paraventricular & suprachiasmatic nuclei
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26
Q

Fill in the blanks . “ The Magnocellular (large) endocrine neurons Release secretions into the circulation by way of the ________.”

A

Posterior pituitary

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27
Q

What controls the functions of Magnocellular secretions?

A

Cholinergic and Noradrenergic neurotransmitters

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28
Q

The Magnocellular neurons release what substances ?

A

ADH (Vasopressin) & Oxytocin

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29
Q

Fill in the blanks. “ ________ stimulates the release of ADH and oxytocin by the Magnocellular neurons. “

A

Acetylcholine (Ach)

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30
Q

Fill in the blanks. “ ________ inhibits the release of ADH and oxytocin by the Magnocellular neurons. “

A

Norepinephrine

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31
Q

True or False? Parvicellular Neurons are innervated by monoaminergic neurons (norepinephrine, dopamine, serotonin) which modulate the hypothalamic release of the hypophysiotropic hormones.

A

TRUE!!

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32
Q

Which substance is found as an intermediator for all steroid-secreting cells?

A

Progesterone

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33
Q

What is Progesterone produced by?

A

It is produced by Corpus Luteum and Placenta

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34
Q

What are the three forms of Estrogens?

A

Estrone (E1)
Estradiol (E2)
Estriol (E3)

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35
Q

Which forms of Estrogens are produced by the Ovaries?

A

Estrone (E1) & Estradiol (E2)

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36
Q

Which forms of Estrogens are produced by the Placenta?

A

Estrone (E1), Estradiol (E2)& Estriol (E3)

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37
Q

What are the metabolic effects of Estrogen?

A

Increase Lipogenesis Increase Protein synthesis
Maturation of bones
X growth (post puberty)

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38
Q

What effect does Estrogen have on the Cardiovascular System?

A

Increase in HDL
Increase in Platelet aggregation
Decrease in CT “ Cutting time”

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39
Q

Fill in the blanks.” Androgens are produced by ________.”

A

Leydig cells

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40
Q

What is the Active metabolite of Androgens?

A

5α - dihydrotestosterone

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41
Q

Which Adrenocortical hormone is a steroid responsible for different concentration of energy/electrolyte?

A

Mineralocorticocoid

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42
Q

Which Adrenocortical hormones is responsible for sugar concentration and has anti-inflammatory properties?

A

Glucocorticoid

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43
Q

Aldosterone is produced by?

A

The Glomerulosa Zone

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44
Q

Where is the site that Aldosterone acts on?

A

Distal Convoluted tubules

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45
Q

What is Cortisol produced by?

A

Produced by Fasciculata reticularis zone ( Inner cortical region of the adrenal gland)

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46
Q

True or False? Glucocorticoids causes and INCREASE in blood sugar and liver glycogen deposit .

A

TRUE!!

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47
Q

The actions of cortisol interferes with which normal cellular processes?

A

Inflammation
Wound healing
Growth

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48
Q

True or False? Cortisol can be used in as palliative agents in the treatment of Asthma & Allergies .

A

TRUE!!

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49
Q

Which neurons release their product into the capillaries of the median emminence?

A

Parvicellular Neurons

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50
Q

Which hormone has a single chain of 41 amino acids?

A

Corticotrophin -releasing hormone.

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51
Q

Which hormone has a peptide of three amino acids?

A

Thyrotropin-releasing hormone.

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52
Q

What are the features of the Endocrine system?

A
  • Slow speed of response
  • Information conveyed by hormones
  • Self-regulating
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53
Q

Where are Peptide hormones synthesised and released?

A

They are synthesised in the Rough ER , stored in vesicles and released by exocytosis.

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54
Q

Where are Steroid hormones synthesised?

A

In the Smooth ER

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55
Q

Secretions of Hormones within approximately one hour is described as?

A

Circhoral

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56
Q

Secretions secreted within more than an hour but less than 24 hours can be described as ?

A

Ultradian

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57
Q

Secretions of hormones done within approximately 24 hours is called?

A

Circadian or diurnal

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58
Q

Secretions of hormones for a period longer than one day considered?

A

Infra-radian

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59
Q

What are examples of circhoral hormones?

A

Pulsatile secretion of renin, oestradiol & progesterone

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60
Q

How are insoluble hormones transported?

A

By albumin and globulin

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61
Q

What are examples of Autocrines?

A

Eicosanoids ( prostaglandins, thromboxanes, prostacyclins,leukotrienes)

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62
Q

What are examples of Paracrines?

A

Somatostatin , Histamine, Eicosanoids

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63
Q

Where are receptors for the water soluble hormones found?

A

On the surface of the target cell , on the plasma membrane.

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64
Q

Where are receptors for the lipid soluble hormones found?

A

They are found in the nucleus ( and sometimes in the cytoplasm ) of the target cell.

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65
Q

The lipid soluble hormone diffuses into the cell and binds to the receptor . After,where does the receptor-hormone complex binds to?

A

It binds to specific DNA sequences called response elements.

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66
Q

What are examples of Anterior pituitary hormones?

A

Human Growth hormone
TSH
ACTH
FSH
LH
Prolactin
MSH ( Melanocyte stimulating hormone)

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67
Q

What are examples of lipid-soluble hormones?

A

Aldosterone
Calcitriol
Testosterone
Estrogen
Progesterone
T3 & T4

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68
Q

Fill in the blanks. “Hormonally induced negative regulation of receptors is referred to as _____________.”

A

Homologous-desensitization.

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69
Q

What is Heterologous desensitization ?

A

Heterologous desensitization occurs when exposure of the cell to one agonist reduces the responsiveness of the cell to any other agonist that acts through a different receptor.

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70
Q

What is Down regulation?

A

Decrease in target cell receptors when excess hormone is present.

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71
Q

What is Up regulation?

A

Increase in target cell receptors when there is hormone deficiency

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72
Q

What is Metabolic Clearance rate?

A

Metabolic clearance rate is the volume of plasma cleared of the hormone per unit of time.

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73
Q

What is the half life for Amine hormones?

A

2-3 min

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74
Q

What is the half life for Steroid hormones?

A

4-120 min

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75
Q

How can one determine the measurement of hormones?

A
  • Radioimmunoassay
  • Chemiluminescence
  • Enzymatic detection (ELISA) for radioactivity
  • Mass spectrometry
76
Q

Hypersecretion of Thyroxine can cause what disease?

A

Grave’s disease

77
Q

Hyposecretion of Thyroxine can cause what disease?

A

Goiter

78
Q

Tertiary Endocrine diseases has occurs where?

A

At the level of the hypothalamus

79
Q

What are the secretory cells for Acidophils?

A

Somatotrope
Lactotrope

80
Q

What are the secretory cells for Basophils?

A

Corticotrope
Thyrotrope
Gonadotrope

81
Q

Somatotropes produce what hormone?

A

Human growth hormone (hGH)

82
Q

Lactrotropes produce what hormone?

A

Prolactin (PRL)

83
Q

Corticotropes produce what hormone?

A

Adrenocorticotropin (ACTH)

84
Q

Thyrotropes produce what hormone?

A

Thyroid-Stimulating hormone.

85
Q

Gonadotrope prodcuces what hormone?

A

Luteinizing hormone (LH) & Follicle stimulating hormone (FSH)

86
Q

Adrenocorticotropic hormone (ACTH) is stimulated by what hormone and from where?

A

It is stimulated by Cortico- Releasing hormone(CRH) in the hypothalamus.

87
Q

What substance potentiates the release of Adrenocorticotropic hormone?

A

Vasopressin

87
Q

Fill in the blanks. “ Thyroid stimulating hormone is stimulated by _______.”

A

Thyrotropin-releasing hormone (TRH)

88
Q

What inhibits Thyroid stimulating hormone?

A

T3 (Triiodothyronine) ,T4 (Thyroxine) & Stress.

89
Q

True or False? TSH is low in hypothyroidism of pituitary origin, but elevated in hypothyroidism of thyroidal origin.

A

TRUE!!

90
Q

FSH is stimulated by ?

A

Gonadotropin-releasing hormone (GnRH) & Activin.

91
Q

Fill in the blanks. “FSH secretion is inhibited by _______.”

A

Inhibin

92
Q

What are the consequences of a Hypophysectomy?

A
  • Growth retardation
  • Hypothyroidism
  • Atrophy of the adrenal cortex
  • Infertility
93
Q

Which hormone is a potent inhibitor of Growth hormone?

A

Somatostatin

94
Q

What is the circulating half life of Growth hormone?

A

20 minutes

95
Q

What are the actions of Growth hormone?

A
  • Promote growth of soft tissues, cartilages and bones.
  • Growth-promoting action mediated by IGF-1.
  • Increase blood glucose.
  • Increase protein synthesis.
  • Increase free fatty acid levels
96
Q

Where produces the highest concentration of Gherlin?

A

The fundus of the stomach

97
Q

True or False? Grhelin decreases growth hormone production after a meal.

A

FALSE!! It increases growth hormone production.

98
Q

A lack of Growth Hormone receptors results in ?

A

Laron dwarfism

99
Q

What are the symptoms of Acregomegaly?

A
  1. Large Nose & Jaw
  2. Galactorrohea
  3. Sexual dysfunction
  4. Cardiomegaly
  5. Hypertrophy of sweat & sebaceous glands
100
Q

What is the formula to calculate Eunucnoid proportions?

A

2C/ (A+B) >1.0

The ratio of a full arm span (C x 2 ) to full body height (A+B) is greater than 1.0

101
Q

What are the different Eunucnoid Body Shapes?

A
  • Congenital/ Early-life - Broad pelvis.
  • Pre-pubertal - Broad pelvis & narrow shoulders.
  • Post-pubertal - Narrow pelvis & narrow shoulders.
102
Q

Which hormone has a 199 amino acid single chain?

A

Prolactin

103
Q

True or False? Lactotropes are not apart of an endocrine axis.

A

TRUE!!

104
Q

Fill in the blanks. “ Production of Prolactin is under inhibitory control by the hypothalamus via______.”

A

Dopamine

105
Q

What are factors that stimulate Prolactin?

A

– sleep
– exercise
– stress
– nipple stimulation
– pregnancy

106
Q

What are Prolactin releasing factors?

A
  • Thyrotropin-releasing hormone (TRH)
  • Angiotensin II
  • AVP
  • SubstanceP
  • Beta-endorphin
106
Q

What inhibits Prolactin release?

A
  • Prolactin-inhibiting factor.
  • Serotonin antagonists & dopamine agonists block secretion of prolactin.
107
Q

Which type of drugs can stimulate Prolactin secretion?

A
  • Dopamine antagonists (phenothiazine & tranquilizers)
  • Adrenergic blockers
  • Serotonin agonists
108
Q

What is the normal prolactin levels in males?

A

2 – 18 ng/ml

109
Q

What is the normal prolactin levels in non-pregnant females?

A

2 – 29 ng/ml

110
Q

What is Homonymous hemianopsia (or hemianopia)?

A

This is a field loss deficit in the same halves of the visual field of each eye, often resulting from cerebrovascular injury or tumor.

111
Q

What is a significant diagnostic indication of a Hypothalamic disease?

A

Diabetes insipidus (due to vasopressin (AVP) deficiency)

112
Q

Which nucleus controls Autonomic and Endocrine function?

A

Paraventricular nucleus

113
Q

Which neurons release secretions into the portal vasculature to stimulate or inhibit secretions from the anterior pituitary?

A

Parvicellular (small) neurosecretory neurons

114
Q

True or False? Sleep, pain, exercise, stress and morphine induce ADH release.

A

TRUE!!

115
Q

What substance inhibits ADH release?

A

Alcohol

116
Q

What is the amount of Iodine needed daily to maintain normal thyroid
function in adults?

A

120-150 μg

117
Q

Fill in the blanks. “The transport of iodide into follicular cells is dependent upon a __________.”

A

Na+/I- cotransport system

118
Q

Where does oxidation of Iodide take place?

A

Occurs in follicular cells

119
Q

What are the three types of proteins thyroid hormones are bound to?

A

a. Thyroxine binding globulin … 80%
b. Thyroxine binding pre-albumin … 10%
c. Plasma albumin (serum albumin) … 10%

120
Q

What is the duration for sufficient storage of T3 & T4 in the Thyroid glands?

A

2-3 months

121
Q

What is the name of the transporter that binds thyroglobulin thereby facilitating the secretion of T4 and T3 into the blood stream?

A

Megalin

122
Q

Which Thyroid hormone is considered active ?

A

3,5,3’- T3 Triiodothyronine (10%)

123
Q

Where is Thyroxine-binding globulin (TBG) synthesized?

A

In the Liver

124
Q

What are examples of Endogenous & Exogenous agents that suppress Thyrotropin secretion?

A
  • Thyroid hormones and analogues
  • Dopamine and dopamine agonists
  • Somatostatin and somatostatin analogues
  • Dobutamine
  • Glucocorticoids (acute, high-dose)
  • Interleukin – 1, Interleukin-6
  • Tumor necrosis factor
  • Bexarotene (retinoid X receptor agonist)
    *Phenytoin
125
Q

Which substance stimulates proopiomelanocortin (POMC) -secreting hormones?

A

Leptin

126
Q

What are the main functions of Leptin?

A
  • Tells the brain how much fat is stored.

*Decreases appetite and increases metabolism.

127
Q

Where is Thyrotropin - releasing hormone produced from?

A

Hypothalamic paraventricular nucleus (PVN

128
Q

Which hormones involve the suppression of neurons in the arcuate nucleus that release Neuropeptide Y (NPY) and Agouti-related protein (AgRP)?

A

Leptin & Insulin

129
Q

Which enzyme inactivates both T4 and T3 is lower whenever there is iodine restriction?

A

D3 ( Type 3 deiodinase)

130
Q

What are the effects of Thyroid hormone on the Cardiovascular system?

A
  • Increased Cardiac output (T3)
  • Increased resting HR, SV
  • Positive chronotropic and inotropic effects
  • Positive lusitropic effect (shortened diastolic relaxation time)
  • Modest increase in SBP and decrease in DBP.
131
Q

True or False? Glycogen & creatinine phosphate are increased by excess T4 & T3

A

FALSE!! It is REDUCED.

132
Q

What is the name of the enzyme that converts any cholesterol not used by cell to cholesterol ester?

A

Acyl CoA-cholesterol acyltransferase (ACAT)

133
Q

What is the name of the enzyme that turns stored cholesterol back into free cholesterol by hydrolyzing the ester bond?

A

Cholesterol esterase / Cholesterol ester hydrolase (CEH)

134
Q

What is the function of the enzyme 3-hydroxy-3 -methylglutaryl CoA reductase (HMG- CoA reductase)?

A

It is involved in the conversion of acetate to cholesterol

135
Q

Where does the beginning of steroid synthesis take place?

A

In the mitochondria

136
Q

What is the name of the protein that is necessary for the transport of cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane?

A

Steroidogenic acute regulatory protein (StAR protein)

137
Q

What is the name of the enzyme attached to the inner mitochondrial membrane that converts Cholesterol to Pregnenolon?

A

CYP 11A1

138
Q

What is the name of the protein to which cortisol is bound to?

A

Corticosteroid-binding globulin [CBG] (also called TRANSCORTIN ),

139
Q

Where is the predominant site of steroid inactivation ?

A

The liver by conjugation with glucuronic acid

140
Q

What is the circulating half life of cortisol?

A

70 mins

141
Q

Fill in the blanks. “ Cortisol is reversible inactivated by conversion to _____.”

A

Cortisone

142
Q

What is the name of the enzyme that catalyses cortisone production ( inactivation of cortisol)?

A

11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2).

143
Q

True or False? Cortisol levels are highest during the eraly morning ( dawn ) and lowest in the evening.

A

TRUE!!

144
Q

What potentiates the action of CRH?

A

ADH

145
Q

What is the name of the receptor to which ACTH binds to?

A

Melanocortin 2 receptor (MC2R)

146
Q

What are the acute effects of ACTH ?

A
  • Cholesterol is rapidly mobilized from lipid droplets by post-translational activation of cholesterol ester hydrolase and transported to the outer mitochondrial
    membrane.

*Increase in StAR protein gene expression and activates StAR protein through protein kinase A (PKA)-dependent phosphorylation
( Over a few minutes)

147
Q

What are the chronic effects of ACTH ?

A
  • These effects involve increasing transcription of the genes encoding the steroidogenic enzymes and their coenzymes.

*ACTH also increases expression of the LDL receptor and scavenger receptor BI (SR-BI; the HDL receptor).

( Occurs over several hours)

148
Q

What are the trophic effects of ACTH ?

A

They act on the zona fasciculata and zona reticularis over weeks and months.

149
Q

Fill in the blanks. “ ____________ inhibits both POMC gene expression at the corticotropes and pro-CRH gene expression at the hypothalamus. “

A

Cortisol

150
Q

What are the Metabolic actions of cortisol?

A
  • Increase Gluconeogenesis
  • Inhibits proteogenesis
  • Stimulate proteolysis
  • Increase Protein breakdown
  • Increase Amino acid release
  • Increase Fatty acid release
151
Q

What is the Zona glomerulosa regulated by?

A
  • The renin- angiotensin system
  • plasma [K+]
  • Atrial natriuretic peptide (ANP).
  • ACTH (minimal)
152
Q

What enzyme is NOT expressed by the zona glomerolosa?

A

CYP17 ( 17- alpha hydroxylse)

153
Q

What reactions in the formation of aldosterone is catalysed by the enzyme aldosterone synthase ( coded by CYP11B2) ?

A
  • 11-hydroxylation of DOC to form corticosterone,
  • 18-hydroxylation to form 18 - hydroxycorticosterone,
  • 18-oxidation to form aldosterone
154
Q

What is the name given to the protein to which Aldosterone is bound to?

A

Albumin and corticosteroid-binding protein.

155
Q

What is the half-life of Aldosterone?

A

20 minutes

156
Q

What is the name of the receptor to which Aldosterone binds to?

A

Mineralocorticoid receptor [MR])

157
Q

Where is the site, synthesis and storage of renin?

A

Juxtaglomerular cells, also known as granular cells

158
Q

Angiotensininogen is produced by the ?

A

Liver

159
Q

Where is Angiotensin I converted to Angiotensin II?

A

In the lungs and renal epithelial cells

160
Q

What is the enzyme that converts Angiotensin I to Angiotensin II?

A

Angiotensin-converting enzyme (ACE)

161
Q

Where is the Angiotensin-converting enzyme (ACE) enzyme located?

A

On the surface of vascular endothelial cells

162
Q

When does the zona reticularis start to appear after birth?

A

At about 5 years of age.

163
Q

What are the main products of the Zona reticularis?

A

Androgens & Dehydroepiandrosterone (DHEA)

164
Q

The enzyme 3β-Hydroxysteroid dehydrogenase (3β-HSD) is expressed in very low levels in which layer of the adrenal cortex?

A

Zona reticularis

165
Q

What is the name of the enzyme that converts DHEA to DHEAS?

A

DHEA sulfotransferase (SULT2A1 gene),

166
Q

Fill in the blanks. “ Most most active sex steroids are produced primarily from __________.”

A

Peripheral conversion of DHEAS and androstenedione.”

167
Q

Fill in the blanks. “DHEAS can be converted back to DHEA by _______.”

A

Peripheral sulfatases

168
Q

What is the half life of DHEA?

A

15-30 minutes

169
Q

What is the half life of DHEAS?

A

7-10 hours

170
Q

True or False? DHEA binds to albumin and other globulins in blood with LOW affinity while DHEAS binds to albumin with very HIGH affinity.

A

TRUE!!

171
Q

What is the most abundant circulating hormone in young adults?

A

DHEAS

172
Q

What is the primary regulator of the zona reticularis?

A

ACTH

173
Q

True or False? Both DHEA and androstenedione display the same diurnal rhythm as cortisol (DHEAS does not because of its long cir- culating half-life).

A

TRUE !!

174
Q

True or False? Cortisol inhibits phospholipase A2?

A

TRUE!!

175
Q

True or False? Cortisol increases bone reabsorption.

A

TRUE!!

176
Q

True or False? Glucoocrorticoids INHIBIT inflammation.

A

TRUE!!

It inhibits -
Arachodonic acid
Platelet activating factor
Tumour Necrosis factor
Interleukin -1
Plasminogen activator.

177
Q

Where is phosphate metabolised?

A

In the bone

178
Q

What is the major anion in bones and teeth?

A

Phosphate

179
Q

What are the functions of Phosphate?

A

 Integral part of glycolytic compounds
 Regulation of blood and urine pH
 Part of energy transfer compounds
 Major anion in bone and teeth

180
Q

What are the actions of Amylin?

A

Inhibits the secretion of glucagon
Slows the emptying of stomach
Sends a satiety signal to the brain

181
Q

What produces Glucagon-like peptide 1 (GLP-1)?

A

L cells

182
Q

What are the two enzymes involved in the degradation of catecholamines?

A

Monoamine oxidase (MAO)
Catechol-O-methyltransferase (COMT)

183
Q
A

Endocrine System (10 decks)

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