Lecture 2 part 2

Question 1

Hormone can influence activity of another hormone at given target cell in one of three ways

Answer 1

• permissiveness
• synergism
• antagonism

Question 2

Permissiveness

Answer 2

One hormone must be present in adequate amounts for full exertion of another hormones effect

Question 3

Synergism

Answer 3

• Occurs when actions of several hormones are complimentary
• Combined effect is greater than the sum of their separate effects

Question 4

Antagonism

Answer 4

• Occurs when one hormone causes loss of another hormone’s receptors
• Reduces effectiveness of second hormone

Question 5

Example of synergism

Answer 5

Cortisol +5 mg/100 ml
Glucagon +10 mg/100 ml
Epinephrine +20 mg/100 ml (added = +35)
Synergistic effect + 140 mg glucose /100 ml blood

Question 6

Example of antagonism

Answer 6

progesterone prevents estrogen function during pregnancy

Question 7

Example of permissiveness

Answer 7

need 2nd hormone to get full expression (thyroid hormone & reproductive hormones; thyroid hormone & epinephrine)

Question 8

Question 9

Endocrine dysfunction causes

Answer 9

• Can arise from a variety of factors
• Most commonly result from abnormal plasma concentrations of a hormone caused by inappropriate rates of secretion

Question 10

Endocrine dysfunction - Hyposecretion

Answer 10

Too little hormone is secreted

Question 11

Endocrine dysfunction - hypersecretion

Answer 11

Too much hormone is secreted

Question 12

Primary hyposecretion

Answer 12

Too little hormone is secreted due to abnormality within gland
Causes:
Genetic
Dietary
Chemical or toxic
Immunologic
Other disease processes such as cancer
Iatrogenic
Idiopathic

Question 13

Secondary hyposecretion

Answer 13

Gland is normal but too little hormone is secreted due to deficiency of its trophic hormone

Question 14

Causes of hypersecretion

Answer 14

Tumors that ignore normal regulatory input and continuously secrete excess hormone
Immunologic factors

Question 15

Primary hypersecretion

Answer 15

Too much hormone is secreted due to abnormality within gland

Question 16

Secondary hypersecretion

Answer 16

Excessive stimulation from outside the gland causes oversecretion

Question 17

Pathologies:
Over or Under Production
“no bad hormones – just too much or too little“
Hypersecretion exaggerates a hormone’s effect (e.g. cortisol)

Answer 17

• Benign (adenomas) & cancerous tumors
• Exogenous medication (iatrogenic – caused by physician)
  > Causes atrophy of gland
  > Cortisol treatment must be tapered of gradually to allow pituitary and
  adrenal gland to gain back normal hormone production

Question 18

Question 19

Pathologies:
Hyposecretion
- due to atrophy of gland

Answer 19

E.g. thyroid hormone
- due to insufficient iodine in diet
- absence or low levels of thyroid hormone
- result: trophic hormone levels rise (negative feedback)

E.g. adrenal cortex atrophies due to tuberculosis
- decrease cortisol production
- result: increased CRH & ACTH production to stimulate adrenal gland to increase cortisol

Question 20

Down-regulation of receptors

Answer 20

Due to abnormal high hormone secretion
E.g. Hyperinsulinemia – sustained high levels of insulin – target cells remove receptors from cell membrane – patients show symptoms of diabetes despite high blood insulin levels

Question 21

Mutations alters protein sequence of receptor

Answer 21

E.g. testicular feminizing syndrome
Androgen receptors are nonfunctional in male fetus
Androgens are unable to influence development of genitalia – child appears to be female with lack of uterus & ovaries

Question 22

Genetic alterations in signal transduction pathways

Answer 22

E.g. pseudohypoparathyroidism
Inherited defect in G-protein that links hormone receptor to cAMP amplifier, adenyl cyclase
PTH levels are normal to high
Symptoms of hormone deficiency

Question 23

Diagnosis of Pathologies depends on complexity of reflex

Answer 23