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HLSC 128 - Human Physiology II > Chapter 7 - The Endocrine Glands > Flashcards

Chapter 7 - The Endocrine Glands Flashcards

1
Q

The thyroid gland consists of ____ lobes of endocrine tissue

A

2

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2
Q

What are the major thyroid secretory cells?

A

follicular cells

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3
Q

What is the functional unit of the thyroid gland?

A

a follicle

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4
Q

What is a follicle?

A

-follicular cells arranged in hollow spheres
-the lumen is filled with colloid

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5
Q

What is the purpose of the colloid?

A

it serves as an extracellular storage site for thyroid hormone (TH)

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6
Q

Thyroglobulin (Tg)

A

-a large protein molecule
-the chief constituent of the colloid

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7
Q

What are the two iodine containing hormones produced by follicular cells?

A

-Thyroxine (aka T4 or tetraiodothyronine)
-Tri-iodothyronine (T3)

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8
Q

What are the iodine-containing hormones derived from?

A

amino acid tyrosine

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9
Q

____% of the hormone secreted is T4 and the other 10% is T3

A

90

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10
Q

Together T3 and T4 make ____

A

thyroid hormone

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11
Q

Where are C cells housed?

A

between the follicles in the interstitial space

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12
Q

What do C cells secrete?

A

calcitonin (calci-bone-in)

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13
Q

What are the two basic ingredients of TH?

A

iodine and tyrosine

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14
Q

How is tyrosine obtained?

A

synthesized by the body (housed in Tg)

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15
Q

How is iodine obtained?

A

dietary intake

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16
Q

Where does TH synthesis occur?

A

on thyroglobulin molecules within the colloid

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17
Q

How is Tg (+ tyrosine) exported into follicular cells colloid?

A

exocytosis

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18
Q

How is iodine brought into colloid?

A

iodine pump

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19
Q

Where does iodine attach to tyrosine?

A

in the colloid

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20
Q

Where is TH stored until they are split off and secreted?

A

in the colloid

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21
Q

Enough TH is stored to supply the body for how long?

A

several months

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22
Q

T3 and T4 are stored bound to _____

A

thyroglobulin

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23
Q

How are T3 and T4 ‘freed’?

A

-follicular cells phagocytize a piece of colloid to break the Tg molecule down
-T3 and T4 diffuse across plasma membrane into the blood

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24
Q

How many iodine molecules does T3 contain?

A

3

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25
Q

How many iodine molecules does T4 contain?

A

4

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26
Q

What type of hormone is TH?

A

amine

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27
Q

How many tyrosines are attached to TH?

A

2

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28
Q

Is TH lipophilic or hydrophilic?

A

lipophilic

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29
Q

How does TH transport in the blood?

A

bound to plasma proteins

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30
Q

What plasma protein transports TH

A

thyroxine-binding globulin

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31
Q

What is the major biologically active form of TH? Why?

A

-even though the majority of TH released is in T4 form, target cells at the liver and kidney take off one of the iodine molecules and convert it to T3
-T3 is 4x stronger than T4

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32
Q

How many cells in the body have receptors for TH in their nuclei?

A

almost all of them

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33
Q

What does TH do to cells?

A

-alters gene transcription and protein synthesis (how cells make new proteins)

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34
Q

What are the 3 major actions of TH?

A
  1. metabolic rate and heat production
  2. sympathomimetic (mimic SNS)
  3. growth and CNS development
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35
Q

TH is the main determinant of B_______ M_______ R_____

A

basal metabolic rate

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36
Q

Basal Metabolic Rate

A

the number of calories you burn as your body performs basic life-sustaining functions

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37
Q

TH has what action on BMR?

A

-it is calorigenic, meaning it produces heat

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38
Q

How does TH generate heat?

A

-it stimulates the Na+/K+ ATPase pump and generates heat through glycolysis

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39
Q

Does TH directly alter heart rate?

A

no

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40
Q

What does sympathomimetic mean?

A

-sympathetic mimic
-TH has the ability to mimic the effects of the sympathetic nervous system (fight or flight)

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41
Q

TH has a permissive action on _______.

A

catecholamines (epinephrine)

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42
Q

How does TH mimic the sympathetic NS?

A

-it increases target cell responsiveness to epinephrine by increasing B-adrenoceptors on the heart

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43
Q

What is the sympathomimetic effect of TH?

A

increases heart rate and force of contraction

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44
Q

What is a by-product of TH’s sympathomimetic effect?

A

heat production

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45
Q

TH promotes normal development of the nervous system by…

A

-stimulating GH release and ISF production
-enhances their effects on growth

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46
Q

What can an absence of T3 and T4 during fetal life lead to?

A

congenital hypothyroidism (cretinism)

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47
Q

What is an example of something that leads to congenital hypothyroidism?

A

lack of iodine in pregnant mother

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48
Q

What hormone stimulates the thyroid gland to make and release TH?

A

Thyroid stimulating hormone (TSH)

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49
Q

What can an absence of TSH lead to?

A

thyroid gland atrophy

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50
Q

What can an excess of TSH lead to?

A

-thyroid gland hypertrophy (size of cells) and hyperplasia (amount of cells)
-leads to Goiter (enlarged thyroid gland)

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51
Q

TH secretion is regulated by a ______ -feedback system

A

negative

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52
Q

What hormone is released by the hypothalamus to stimulate TSH secretion?

A

thyroid-releasing hormone (TRH)

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53
Q

What causes hypothyroidism?

A

-Primary: thyroid gland failure
-Secondary: TRH or TSH deficiency
-inadequate iodine supply

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54
Q

What is myxedema?

A

-a term used for hypothyroidism in adults

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55
Q

What causes the edema seen in hypothyroidism?

A

accumulation of mucopolysaccharides under the skin

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56
Q

Symptoms of Hypothyroidism

A

-increased sensitivity to cold (calorigenic)
-weight gain (calorigenic)
-fatigue
-slow, weak pulse
-impaired mental function

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57
Q

How is hypothyroidism treated?

A

-replacement hormone therapy
-dietary idodine

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58
Q

Grave’s Disease

A

-an autoimmune disease that causes by hyperthyroidism
-causes exophthalmos (wide eyes)

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59
Q

What does the body produce in hyperthyroidism?

A

-thyroid-stimulating immunoglobulins (TSI)
-mimic TSH

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60
Q

What are the 3 causes of hyperthyroidism?

A

-Grave’s disease
-excess TRH or TSH secretion
-thyroid tumour

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61
Q

Hypothyroidism causes increased plasma TSH levels, except when…

A

the cause is hypothalamic or anterior pituitary failure

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62
Q

Hyperthyroidism causes decreased plasma TSH levels, except when…

A

the cause is excess hypothalamic or anterior pituitary secretion

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63
Q

What are the symptoms of hyperthyroidism?

A

-heat intolerance
-weight loss
-muscle weakness
-increased apetite
-increased SNS activity (heart rate, anxiety)

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64
Q

How is hyperthyroidism treated?

A

-surgical removal of part of they over secreting thyroid
-radioactive iodine administration
-antithyroid drugs

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65
Q

Where are the adrenal glands located?

A

above each kidney

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66
Q

What encloses the adrenal glands?

A

a capsule of fat

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67
Q

The adrenal cortex is the ______ portion.

A

outer

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68
Q

What type of hormones does the adrenal cortex secrete?

A

steroid hormones

69
Q

The adrenal medulla is the _____ portion.

A

inner

70
Q

What type of hormones does the adrenal medulla secrete?

A

catecholamines (norepinephrine and epinephrine)

71
Q

What are the 3 layers/zones of the adrenal cortex from outward in?

A

-zona glomerulosa
-zona fasciculata
-zona reticularis

72
Q

What does the zona glomerulosa secrete?

A

aldosterone (mineralcorticoids)

73
Q

What does the zona fasciculata secrete?

A

mainly cortisol some DHEA

74
Q

What does the zona reticularis secrete?

A

mainly DHEA some cortisol

75
Q

Which adrenal cortex zone is the largest?

A

the middle zone - zona fasciculata

76
Q

What are the 3 categories of adrenal steroids?

A

-mineralocorticoids
-glucocorticoids
-sex hormones

77
Q

Mineralcorticoids

A

-mainly aldosterone
-influences Na+ and K+ balance

78
Q

Glucocorticoids

A

-mainly cortisol
-role in glucose, protein, lipid metabolism

79
Q

Sex Hormones

A

-identical or similar to those produced by gonads
-DHEA is the most abundant

80
Q

Dehydroepiandrosterone (DHEA)

A

-male ‘sex’ hormone

81
Q

The adrenal cortex hormones are ______ based and hydro ____.

A

cholesterol based; hydrophobic

82
Q

How are steroid hormones carried in the blood?

A

bound to plasma proteins

83
Q

Which plasma protein does cortisol bind to?

A

corticosteroid-binding globulin

84
Q

Which plasma protein do aldosterone and DHEA bind to?

A

albumin

85
Q

Where does aldosterone act?

A

on distal and collecting tubules of the kidney

86
Q

What controls the secretion of aldosterone?

A

the renin-angiotensin-aldosterone system

87
Q

RAAS increases aldosterone secretion when… and results in…

A

-when Na+ reduction is detection with a fall in blood pressure
-directly stimulated by rise in plasma K+ concentration
-results in Na+ reabsorption, water follows to increase blood pressure

88
Q

Aldosterone is __________ of anterior pituitary control.

A

independent

89
Q

What can cause aldosterone hypersecretion?

A

-adrenal tumour made of aldosterone-secreting cells
-Conn’s syndrome (primary)
-high RAAS activity (secondary)

90
Q

What are the symptoms of aldosterone hypersecretion?

A

-high blood pressure
-less urine volume
-highly concentrated urine

91
Q

What is another name for glucocorticoids?

A

corticosteroids

92
Q

What do steroid hormones do?

A

glucose, protein, fat metabolism

93
Q

What is the most abundant steroid hormone?

A

cortisol

94
Q

What are the 4 functions of cortisol?

A

-hepatic glucogenesis
-increases plasma glucose
-stimulates protein degradation
-facilitates lipolysis

95
Q

Hepatic Glucogenesis

A

-conversion of non-carbohydrate sources (ie. amino acids) into carbohydrates in the liver
-cortisol increases this process by up to 10x

96
Q

When is glucogenesis by cortisol important?

A

maintaining glucose levels between meals

97
Q

How does cortisol increase plasma glucose?

A

-by inhibiting glucose uptake by tissues (not the brain)

98
Q

Why does cortisol contribute to protein degradation?

A

-uses the proteins in muscles to get amino acids to make glucose
-why we have muscle breakdown when stressed

99
Q

What is lipolysis?

A

-splitting of adipocytes from triglycerides to increase fatty acids in the blood

100
Q

How does lipolysis contribute to stress adaptation?

A

the fatty acids are used as alternative fuel while glucose is being used for the brain

101
Q

Cortisol has a characteristic dinural rhythm, what does this mean?

A

-its secretion is cyclical, more is secreted in the morning and less at night

102
Q

What are the hormones involved in the cortisol negative-feedback loop?

A

-hypothalamic CRH
-anterior pituitary ACTH

103
Q

What hormone requires the permissive action of cortisol?

A

catecholamines (epinephrine)

104
Q

What does cortisol allow epinephrine to do?

A

-permit induction of vasoconstriction

105
Q

What do cortisol and epinephrine do during stressful situations?

A

-induce vasoconstriction to prevent circulatory shock

106
Q

Cushing’s Syndrome

A

-caused by cortisol hypersecretion when adrenal cortex is overstimulated by CRH and ACTH

107
Q

What are other causes of cortisol hypersecretion?

A

-adrenal tumour secreting cortisol (ACTH independent)
-ACTH secreting tumours

108
Q

Symptoms of Cushing’s Syndrome

A

-hyperglycaemia (diabetes mellitus levels)
-fat redistribution (buffalo hump and mood face)
-muscle weakness
-osteoporosis
-immunosuppression
-hypertension
-stratia line on skin caused by protein breakdown
-red cheeks

109
Q

How is Cushing’s Syndrome treated?

A

-surgical removal of the pituitary tumour
-adrenalectomy

110
Q

Does the adrenal gland only secrete sex hormones relative to biological sex?

A

No, it secretes both male and female sex hormones in both sexes

111
Q

What is the only adrenal sex hormone that has biological importance?

A

DHEA

112
Q

Which pituitary hormone drives DHEA?

A

ACTH (not FSH or LH)

113
Q

What overpowers DHEA in males?

A

testicular testosterone

114
Q

What does DHEA do in females?

A

-pubic and axillary hair growth
-pubertal growth spurt
-development and maintenance of sex drive

115
Q

What is adrenogenital syndrome?

A

hypersecretion of adrenal androgen

116
Q

Symptoms of adrenogenital syndrome in adult females:

A

-male like body hair (hirsutism)
-deep voice
-muscular arms and legs
-smaller breasts
-possible menstruation caseation

117
Q

Why does excess DHEA production occur?

A

-malfunctioning adrenal gland doesn’t make cortisol in response to ACTH due to absent enzymes
-DHEA production increases

118
Q

How do gonads respond to increased DHEA production?

A

-inhibition of gonadotropins
-no sex hormone or gamete production (sterile)

119
Q

How is adrenogenital syndrome treated?

A

glucocorticoid therapy

120
Q

What are the symptoms of adrenogenital syndrome in newborn females?

A

male-type external genitalia

121
Q

What are the symptoms of adrenogenital syndrome in prepubertal males?

A

-precocious pseudo-puberty (facial hair but no sperm)

122
Q

Does adrenogenital syndrome have an effect on adult males?

A

no

123
Q

The adrenal medulla is a modified part of which nervous system?

A

sympathetic nervous system

124
Q

How does the adrenal medulla respond?

A

releasing their chemical transmitter into circulation

125
Q

What is the primary stimulus of the adrenal medulla?

A

stress

126
Q

What does the adrenal medulla release?

A

catecholamines - 80% epinephrine and 20% norepinephrine

127
Q

How do catecholamine activities differ?

A

depending on the adrenergic receptor type

128
Q

What is another name for epinephrine?

A

adrenaline

129
Q

What does epinephrine do?

A

-reinforce the SNS fight or flight response
-increases heart rate
-increases blood glucose and fatty acids
-inhibits insulin secretion

130
Q

Where are catecholamines stored?

A

chromaffin granules

131
Q

How does epinephrine inhibit insulin secretion?

A

by increasing glucagon secretion

132
Q

Stress Definition

A

a generalized, nonspecific response to any factor that overwhelms the body’s ability to maintain homeostasis

133
Q

Stressor Definition

A

any stimulus that brings about the stress response

134
Q

Generalized Stress Response

A

-↓ insulin secretion
-↑ glucagon secretion
-elevated blood glucose and fatty acids

135
Q

How are blood volume and blood pressure maintained?

A

-increased RAAS activity
-increased vasopressin secretion

136
Q

Metabolism Definition

A

all the chemical reactions that occur within the cells of the body

137
Q

Anabolsim

A

build up or synthesis of larger organic macromolecules from small organic subunits

138
Q

Do anabolic reactions require ATP?

A

usually

139
Q

What do anabolic reactions result in?

A

-manufacture of needed cell materials
-storage of excess nutrients

140
Q

Catabolism

A

breakdown or degradation of large, energy rich organic molecules within cells

141
Q

What are the 2 levels of catabolic breakdown?

A
  1. hydrolysis of large molecules into subunits
  2. oxidation of subunits to yield ATP energy
142
Q

What are the most important hormones in regulating fuel metabolism?

A

insulin and glucagon

143
Q

What are the endocrine cells in the pancreas called?

A

Islets of Langerhans

144
Q

What occurs at Beta cells?

A

insulin synthesis and secretion

145
Q

What do alpha cells produce?

A

glucagon

146
Q

What do delta cells do?

A

somatostatin synthesis

147
Q

What are the least common islet cells?

A

PP cells

148
Q

What do PP cells secrete?

A

pancreatic polypeptide

149
Q

Is insulin an anabolic or catabolic hormone?

A

anabolic

150
Q

What is the major insulin stimulus?

A

blood glucose

151
Q

When is insulin secretion increased?

A

during absorptive state

152
Q

Insulin promotes the cellular uptake of g_____, f___ a____, and a_____ a____

A

glucose, fatty acids, amino acids

153
Q

What does insulin turn glucose into?

A

glycogen

154
Q

What does insulin turn fatty acids into?

A

triglycerides

155
Q

What does insulin turn amino acids into?

A

proteins

156
Q

What factors increase blood glucose?

A

-GI tract glucose absorption
-hepatic glucose production (glycogenesis of stored glucose, glucogenesis)

157
Q

What factors decrease blood glucose?

A

-glucose transport into cells for energy production or storage (as glycogen or triglycerides)
-urinary glucose excretion

158
Q

Insulin _____ blood glucose

A

decreases

159
Q

Insulin ____ blood fatty acids

A

decreases

160
Q

Insulin ______ blood amino acids

A

decreases

161
Q

Insulin ______ protein synthesis

A

increases

162
Q

Insulin _______ fuel storage

A

increases

163
Q

What is the most common endocrine disorder?

A

diabetes mellitus

164
Q

_______ blood glucose levels is the prominent feature of diabetes mellitus.

A

elevated

165
Q

What is type I diabetes?

A

lack of insulin secretion to store glucose

166
Q

What is the occurrence of type I diabetes?

A

10%

167
Q

What is type II diabetes

A

characterized by normal insulin secretion but reduced sensitivity of insulins target cells (insulin resistance)

168
Q

What is the occurrence of type II diabetes?

A

90% (more common)

169
Q

What is a classic sign of diabetes mellitus?

A

-polyuria (large urine production)
-glucose in urine, water stays with glucose (osmotic diuresis)

HLSC 128 - Human Physiology II (11 decks)

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