Chapter 7- The Endocrine Glands Flashcards
(158 cards)
1
Q
What is the thyroid gland?
A
Two lobes of endocrine tissue joined in missile by narrow portion of gland
2
Q
What are the functional unit of the Thyroid?
A
Follicular cells (follicle)
3
Q
How are follicular cells arranged in the thyroid gland?
A
Into hollow spheres which form a follicle
4
Q
What is the lumen of follicular cells filled with?
A
Coloid
5
Q
What is the function of coloid in follicular cells?
A
Serves as extracellular storage for thyroid hormone
6
Q
What kind of hormones does the thyroid produce?
A
Two iodine-containing hormones derived from amino acid tyrosine
7
Q
What are the 2 hormones that the thyroid produces?
A
Tetraiodothyronine (T4 or thyroxine)
Triiodothyronine (T3)
8
Q
What neuroendocrine cells does the thyroid have?
A
C cells
9
Q
What do C cells secrete?
A
Peptide hormone called Calcitonin
10
Q
What is the thyroid gland responsible for?
A
Synthesis, storage and secretion of thyroid hormone
11
Q
What are the 2 basic ingredients of thyroid hormone?
A
- tyrosine (synthesised by body)
- Iodine (dietary intake)
12
Q
Where does synthesis of TH occur?
A
On thyroglobulin molecules with colloid
13
Q
How does tyrosine enter the colloid?
A
Tyrosine-containing thyroglobulin is exposed from follicular cells into colloid via exocytosis
14
Q
How does the iodine enter the colloid?
A
via Iodine pump after thyroid captures iodine in the blood
15
Q
What happens to tyrosine and iodine in the colloid?
A
Iodine attaches to tyrosine and forms thyroid hormones
16
Q
How does thyroid store thyroid hormone?
A
Remind in colloid
-Until split off and secreted
-Enough is stored to supply body for several months
17
Q
How are thyroid hormones secreted?
A
Follicular cells phagocytise thyrogolbin-laden colloid which frees T3 and T4 to diffuse into blood
18
Q
What kind of hormones is thyroid hormone?
A
Amine
-has 2 tyrosines
-Has iodine
19
Q
What is the chemical nature of thyroid hormone?
A
Lipophilic
-Transported by plasma protein
20
Q
What percent of each thyroid hormone is produced?
A
T4 - 90%
T3 - 10%
21
Q
Why is T3 produced less than T4?
A
because T3 is four times more potent than T4
22
Q
Where are the target cells that cleave iodine to form T4?
A
Mainly in the liver and kidney
23
Q
What plasma protein does T4 bind with?
A
Thyroxine-binding globulin
24
Q
Where are receptors for thyroid hormones found?
A
Nuclei of most of the cells in the body
-allows for widespread action
25
What are thyroid hormone major actions?
1. basal Metabolic rate and heat production
2. Sympathomimetic (permissive action)
3. Growth and CNS development
26
How does thyroid hormone determine basal metabolic rate?
-Stimulates Na/K ATPase
-Generates heat during glycolysis
-Calorigenic action
27
What is thyroid hormone's sympathomimetic effect?
Increases target-cell responsiveness to catecholmines
28
How does thyroid hormone have a sympathomimetic effect?
Permissive action
Increases HR and force of contraction
-Increase b-adenorecptors on heart
29
How does thyroid hormone effect nervous system development?
Hormones help develop the nervous system properly
-lack of hormone can affect growth
30
What happens if there is an absence of T3 and T4 during fetal life?
Congenital hypothyroidism
(cretinism)
31
What is the effect of Congenital hypothyroidism?
poorly developed NS and severely compromised intellectual function
32
What can cause Congenital hypothyroidism ?
Lack of iodine in pregnant mother
33
How is thyroid hormone essential for normal growth?
Stimulates Gh release and IGF-1 production
Enhances effects of GH and IGF-1 on target cells
34
What is the function of TSH?
Regulates steps in thyroid hormone synthesis and release
35
What happens if there is an absence of TSH?
Thyroid gland atrophy
36
What happens if there is an excess of TSH?
Thyroid gland hypertrophy and hyperplasia causing a Goiter
37
What regulates thyroid gland secretion?
A negative-feedback system
-Hypothalmic TRH
-Anterior pituitary TSH
-Thyroid gland T3 and T4
38
What are two main categories of abnormalities of the thyroid gland?
1. Hypothyroidism
2. Hyperthyroidism
39
What is th term often used for Hypothyroidism in adults?
Myxedema
40
What does Myxedema cause?
Mucopolysaccharides accumulate under the skin forming an edna
41
What are the symptoms of Hypothyroidism??
Increased sensitivity to cold -calorigenic
Weightgainc–calorigenic
Easily fatigued
Slow weak pulse –cardiac
Impaired mental function
42
How is Hypothyroidism treated?
-replacement hormone therapy
-Dietary iodine
43
What may occur with hypothyroidism?
Goiters
(Too much TSH)
44
How are goiters treated?
-Exogenous thyroid hormone
-Dietary iodine if its a deficiency causing it
45
What is the most common cause of hyperthyroidism ?
Grave's disease
(autoimmune disease)
46
What is Grave's disease?
Body incorrectly produces thyroid-stimulating immonoglobulines which act like TSH
47
What is a prominent characteristic of those with Grave's disease?
Exophthalmos
-Protruding eyes
48
What are symptoms of hyperthyroidism?
Heat intolerance
Weight loss including skeletal muscle
Increased appetite
Increased SNS activity: anxiety, tremors, increased HR
49
How is hyperthyroidism treated?
-Surgical removal of portion of the over-secreting thyroid
-radioactive iodine
-Antithyroid drugs
50
What are adrenal glands?
Glands embedded above each kidney in a capsule of fat
51
What are the two exocrine organs composing the Adrenal glands?
1. Adrenal cortex
2. Adrenal medulla
52
What is the adrenal cortex?
Outer portion
53
What doe the adrenal cortex secrete?
Steroid hormones
54
What does the adrenal medulla secrete?
catecholamines
(epinephrine and NE)
55
What are the 3 zones/layers of the adrenal cortex? (outmode to innermost)
Zona golerulosa
Zona fasciculata
Zona reticularis
56
What does the Zona glomerulosa secrete?
Aldosterone
(outermost layer)
57
What does the Zona fasciculata secrete?
Main source of Cortisol
DHEA
(middle layer)
58
What does the Zona reticularis secrete?
DHEA
some cortisol
(innermost layer)
59
What is the largest portion/layer of the adrenal cortex?
Zona fasciculata
60
What are the 3 categories of adrenal steroids?
1. Mineralocorticoids
2. Glucocorticocoids
3. Sex hormones
61
What are Mineralocorticoids?
Influence mineral balance (Na and K)
Mainly aldosterone
62
What are glucocorticoids?
Major role in glucose metabolism and protein and lipid matabolism
Mainly cortisol
63
What are sex hormones?
Identical or similar to those produced by the gonads
-Most important is DHEA
64
What is DHEA?
dehydroepiandosterone
(male "sex" hormone)
65
What are all adrenal cortex hormones based from?
All cholesterol-based
66
What is the chemical nature of cholesterol-based hormones?
Hyrophopic
Carried by plasma proteins in blood
67
What plasma protein is Cortisol bound to?
Corticosteroid-binding globulin (transcortin)
68
What plasma protein is aldosterone and DHEA bound to?
Albumin
69
what is aldosterone's principal action site?
Distal and collecting tubules of the kidney
70
What increases aldosterone secretion?
Renin-angiotensin-aldosterone system
71
How is the RAS triggered?
When blood sodium levels drop or potassium levels rise Renin is released by the adrenal glands
72
What s aldosterone's function?
Help kidney's retain sodium and excrete potassium
73
What part of the brain does aldosterone act independently of?
The anterior pituitary
74
What are 2 main disorders of adrenocortical function?
1. Aldosterone hypersecretion
2. Adrenoctical insufficiency
75
What can cause aldosterone hyper secretion?
-Hypersecreting adrenal tumour made of adolsterone-secreting cells
-Inapropriately high activity of RAS
76
What does a hypersecreting aldosterone tumour cause?
Primary hyperaldosteronism aka Conn's syndrome
77
What does inappropriately high activity of the RAS cause?
Secondary hyperaldosteronism
78
what are symptoms of Aldosterone hyper secretion?
-Excessive Na retention and K depletion
-HIGH blood pressure
79
What causes Primary adrenocortical insufficiency?
Addison's disease
Autoimmune disease (most common)
Loss of cortical region
-Leads to aldosterone and cortisol deficiencies
80
What does an aldosterone deficiency cause?
-Hyperkalemia and hyponatremia, hypotension
81
What does a cortisol deficiency cause?
Poor response to stress
Hypoglycemia
Lack of permissive action for many metabolic activities
82
Why does secondary adrenocortical insufficiency occur?
Occurs because of pituitary or hypothalamic abnormality
83
What hormone does secondary adrenocortical insufficiency cause a deficiency of?
ONLY CORTISOL
-No hypothalamic hormones to trigger the release of it
84
What is the most abundant Glucocorticoid? aka Corticosteroids
Cortisol
85
What does cortisol stimulate?
-Hepatic gluconeogenesis
-Protein degradation in tissue especially muscle
86
What is Hepatic gluconeogenesis
the process where the liver makes new glucose molecules from non-carbohydrate sources
e.g; amino acids
87
What does Cortisol inhibit?
Glucose uptake and use by many tissues (not the brain tho)
-Increases plasma glucose
88
What does cortisol facilitate?
Lipolysis
-Fatty acid increases in blood
89
What emotion does cortisol play a key role in adapting to?
Stress
90
What is cortisol secretion regulated by?
negative-feedback loop involving CRG and pituitary ACTH
91
Cortisol displays a charecteristic _______ _______
Dinural Rhythm
-Cortisol levels are highest in the morning and lowest at night
92
Cortisol is a permissive action hormone, what hormones requires its presence?
Permits catecholamines, epinephrine
93
What does epinephrine require cortisol for?
To induce vasoconstriction to prevent circulatory shock in stressful situations
94
What is the same for Cortisol hyper secretion?
Cushing's syndrome
95
What causes Cushing's syndrome?
1. Overstimulation of adrenal cortex by excessive amounts of CRH and ACTH (Cushing's disease -most common)
2, Adrenal tumours that secrete cortisol independent of ACTH
3. ACTH-secreting tumours located in places other than the pituitary
96
What does Cushing's syndrome cause?
Hyperglycemia -diabetes mellitus levels
Redistribution of fat
Muscle weakness
Osteoperosis
Immunosuppression
Hypertension
Hypercortisolism stratia
Thin legs and arms, fat on trunk and face
Red cheeks
97
How is fat redistributed in Cushing's syndrome patients?
Buffalo hump
Moon face
98
What causes Hypercortisolism-stratia in Cushing's syndrome patients?
Protein breaks down in skin
-Stretch mark-like appearance
99
How is Cushing's syndrome treated?
Depends on the cause:
-Surgial removal of pituitary tumour
-Adrenalectomy
100
What sexes does the adrenal cortex produce sex hormone in?
Both
101
What is the name of the adrenal sex hormone with biological importance?
DHEA
Dehyroepiandrosterone
102
In males what happens when DHEA is secreted?
It is overpowered by testicular testosterone
103
In females when DHEA is secreted?
-Causes pubic and axillary hair growth
-Enhances pubertal growth spurt
-Develops and maintains female sex drive
104
What hypothalamic hormone controls DHEA?
ACTH
-not gonadotropins FSH and LH
105
What is the name for Adrenal androgen hyper secretion?
Adrenogenital syndrome
106
What are symptoms of Adrenogenital syndrome in Adult females?
Hirsutism (male like body hair)
Deepening of voice
More muscular arms and legs
Smaller breasts
Menstruation ceases
107
What can cause Adrenogenital syndrome?
Cortisol insufficiency
-because it increases ACTH, which stimulates DHEA
108
What does DHEA inhibit?
Gonadotropins
-during hyper secretion of DHEA can lead to sterility
109
How is Adrenogenital syndrome treated?
Glucocorticoid therapy
110
What are the symptoms of Adrenogenital syndrome in newborn females?
Have male-type external genitalia
111
What are symptoms of Adrenogenital syndrome in Prepubertal males?
precocious pseudopuberty
112
What are symptoms of adrenogenital syndrome in Adult males?
No apparent effect
113
What nervous system is the adrenal medulla a modified part of?
The sympathetic nervous system
114
What is the primary stimulus of the adrenal medulla?
Stress
115
What hormones does the adrenal medulla release?
Catecholamines
116
How much of each catecholamine does the adrenal medulla release?
Epinephrine 80%
Norepinephrine 20%
117
Why do the actives of adrenal medulla catecholamine vary?
Their activities depend on different adrenergic receptor types
-alpha and beta adrenoceptors
118
What are the functions of Epinephrine?
aka Adrenlaline
-reinforces SNS (systemic response to fight or flight)
-Maintains arterial BP
-increases blood glucose and blood fatty acids
119
How does epinephrine increase blood glucose and blood fatty acids?
-Stimulates Gbuconeogensis in the liver
-Stimulates glycogenolysis in the liver and skeletal muscles
-Inhibits insulin secretion
-increase glucagon secretion
120
What is a stress response?
Pattern of reactions to a situation that threatens homeostasis
121
What is stress?
nonspecific response of body to any factor that overwhelms the body’s ability to maintain homeostasis
122
What is a stressor?
Any harmful stimulant that brings about the stress response
123
Examples of stressors?
Physical – hot/cold, trauma
Chemical – reduced O2
Physiological – exercise, pain ● Infections - bacterial
Emotional – anxiety, sorrow
Social – lifestyle changes
124
What is the stress responses actions coordinated by?
Hypothalamus
125
What does a generalised stress response activate?
SNS
CRH-ACTH-cortisol system
126
Why does a stress response activate the SNS?
Prepare body for fight-or flight response
-Epinephrine
127
Why does a stress response activate the CRH-ACTH-cortisol system?
Helps body cope by mobilizing metabolic resources
128
What does a genralized stress response cause?
Elevation of blood glucose and fatty acids
Maintaince of blood volume and blood pressure
129
How is blood glucose and fatty acids elevated during a stress response?
Insulin decreases
Glucagon increases
130
What is metabolism?
All the chemical reactions that occur within the cells of the body
131
What is intermediary/fuel metabolism?
Includes reactions involving the degradation, synthesis, and transformation of proteins, carbohydrates, and fats
132
What is anabolism?
buildup or synthesis of larger organic macromolecules from small organic subunits
■■■■ ----> █
133
What do anabolism reactions require?
ATP energy
134
What do anabolism reactions result in?
1. Manufacture of materials needed by the cell
2.Storage of excess ingested nutrients not immediately needed for energy
135
What is Catabolism?
breakdown or degradation of large, energy-rich organic molecules within cells
█ ----> ■■■■
136
What are the two levels of catabolism breakdown?
1. Hydrolysis of large molecules into smaller subunits
2. Oxidation of smaller subunits to yield energy for ATP production
137
What hormones are most important in regulation fuel metabolism?
Insulin and glucagon
138
What are the endocrine cells of the pancreas called?
Islets of Langerhans
139
What are the 4 specific islet cells in the endocrine pancreas?
1. β (beta) cells
2. α (alpha) cells
3. δ (delta) cells
4. PP cells
140
What do β (beta) cells do?
Site of insulin synthesis and secretion
141
What do α (alpha) cells do?
Produce glucagon
142
What do δ (delta) cells do?
Pancreatic site of somatostatin synthesis
143
What are PP cells?
Least common islet cell
Secretre pancreatic polypeptide
144
What kind of hormone is Insulin?
Anabolic hormone
145
When does the secretion of insulin increase?
During absorptive state
146
What is a major stimulus of insulin secretion?
Blood glucose concentration
147
What does insulin promote the cellular uptake of?
-Glucose
-Fatty acids
-Amino acids
*lowers blood concentration of them
148
What does insulin covert glucose to?
Glycogen
149
What does insulin convert fatty acids to?
Tryglycerides
150
What does insulin convert amino acids to?
Proteins
151
What is the most common endocrine disorder ?
diabetes mellitus
152
What is a prominent feature of diabetes mellitus?
Elevated blood glucose levels
Glucose in urine
153
What are the 2 major types of diabetes mellitus?
Type I
Type II
154
What percentage of people with diabetes mellitus have each type?
10% have Type I
90% have Type II
155
What is Type I diabetes?
Lack of insulin secretion
156
What is Type II diabetes?
Normal or increased insulin secretion
-Insulin's target cells are less sensitive
157
What is a classic sign of diabetes mellitus?
Polyuria
-Large urine volume produced
158
Why does diabetes mellitus cause polyuria?
Extra glucose exceeds capacity of nephron to absorb it
● With glucose, stays water=osmotic diuresis, causing “sweet urine”
