CHAPTER 32
DISORDERS OF ENDOCRINE FUNCTION
Essentials of Pathophysiology
PRE LECTURE QUIZ TRUE/FALSE
Hypopituitarism is characterized by a decreased secretion of pituitary hormones.
Hypothyroidism is evidenced by an increased metabolic rate, restlessness, irritability, tachycardia, diarrhea, and heat intolerance.
Primary adrenal insufficiency, or Addison disease, is caused by destruction of the adrenal gland.
Moon facies, buffalo hump, obesity, amenorrhea, and increased facial hair are manifestations of Cushing syndrome.
Addison disease is a temporary condition.
T
F
T
T
F
PRE LECTURE QUIZ In children, _____________ hormone deficiency
interferes with linear bone growth, resulting in short stature or dwarfism.
When growth hormone excess occurs in adulthood or after the epiphyses of the long bones have fused, the condition is referred to as ______________.
Precocious ______________ is the early activation of the hypothalamic-pituitary-gonadal axis, resulting in the development of appropriate sexual characteristics and fertility.
______________ disease is a state of hyperthyroidism that is often accompanied by goiter and exophthalmos.
______________ syndrome refers to the manifestations of excess cortisol.
Acromegaly
Cushing
Graves
growth
puberty
HYPOTHALAMUS- PITUITARY AXIS
Releasing hormones from hypothalamus tell the pituitary what to release into the blood
Trophic hormones from the pituitary tell specific peripheral glands to grow and produce their hormones
Releasing Hormones
Trophic Hormones
Primary: abnormality in the gland
Secondary: abnormality in stimulation from the pituitary
Tertiary: abnormality in stimulation from the hypothalamus
HORMONE DISORDERS
PITUITARY HORMONES
Growth hormone
FSH and LH
ACTHTSH
stimulate gonads
stimulates thyroid
stimulates adrenal cortex
QUESTION
Which hormone(s) stimulate the ovaries and testes?
a. GHb. FSH and LHc. TSHd. ACTH and GH
ANSWER
b. FSH and LHRationale: Gonads are sex organs
(ovaries and testes). These organs are stimulated by follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
THE HYPOTHALAMUS CONTROLS GROWTH HORMONE RELEASE
GH secretion stimulated by: Hypoglycemia,
fasting, starvation Stress
GH inhibited by: Increased glucose
levels, free fatty acid release, and obesity
Cortisol
GHRH stimulates
Somatostatin inhibits
Hypothalamus
Anterior pituitary
Growth hormone
GHIHNext
Slide
GROWTH HORMONE SITIMULATED BY ? Hypoglycemia, fasting, starvation,
Stress ??
It would seem that adequate energy supply would be needed for Growth ?
A baseline level of GH exists during normal nutrition mildly stimulated by Deep Sleep, Exercise, and Protein Consumption. GH stimulates IGF-1
During fasting etc. and increased release of GH occurs due to a decrease in GHIH.
This produces a protective effect preventing muscle wasting by stimulating lipolysis and FFA metabolism maintaing blood glucose for the CNS
Without GH significantly more muscle wasting occurs
FUNCTIONS OF GROWTH HORMONE
Promotes Growth Inhibits Insulin
GROWTH HORMONE DEFICIENCY
Idiopathic GH deficiency Lacks hypothalamic GHRH
Pituitary tumors, agenesis of the pituitary Cannot produce GH
Laron-type dwarfism Hereditary defect in IGF
production
GROWTH HORMONE EXCESS
In childhood: gigantism
In adulthood: acromegaly
QUESTION
Tell whether the following statement is true or false.
GH deficiency may result in dwarfism.
ANSWER
TrueRationale: Laron-type dwarfism is
caused by a genetic inability to produce normal amounts of GH. Not True. Normal GH abnormal IGF
THE HYPOTHALAMUS CONTROLS GONADAL HORMONE RELEASE
Excessive GnRH secretion can be stimulated by: Hypothalamic tumors Pituitary tumors
Giving high levels of GnRH causes the pituitary to become less responsive and reduces the effects of abnormal GnRH secretion
GnRH stimulates
hypothalamus
anterior pituitary
FSH
production of gametes and gonadal hormones
LH
THYROID CONTROL
Thyroid releases T3
and T4
Both are carried by binding proteins
T3 stimulates metabolism
T4 is inactive until converted into T3 in the tissues
Both exert negative feedback on the hypothalamus
Why?
THYROID INSUFFICIENCY DUE TO LACK OF I
T3 and T4 are not made
There is no negative feedback to the hypothalamus
TRH and TSH continue to be made
If it is able, the thyroid will grow in response to the TSH
THYROID IMBALANCES
Hypothyroidism
Congenital
Acquired
º Hashimoto thyroiditis
º Thyroidectomy
Hyperthyroidism (thyrotoxicosis)
Graves disease
Thyroid tumors
QUESTION
Tell whether the following statement is true or false.
Simple goiter is caused by increased production of thyroid hormone.
ANSWER
FalseRationale: Simple goiter is the result of
iodine (I) insufficiency. Since I is necessary in order to produce thyroid hormone, a deficiency results in low serum levels of T3 /T4. This causes TSH to stimulate the thyroid gland to make more hormone (which it cannot do because it needs I). The cells of the thyroid gland hypertrophy in an effort to function (make thyroid hormone).
MAJOR ADRENAL CORTICAL HORMONES
• Cortisol• What can cause Cortisol
Stimulation?• Hypothalamus releases ??
• Causes the Anterior
Pituitary to release ??• Causes the adrenal cortex
to release ??
MAJOR ADRENAL CORTICAL HORMONES
Negative feedback
Negative feedback
Hypothalamus
Corticotropin-releasing hormone (CRH)
Anterior pituitary
Adrenal corticotrophic hormone (ACTH)
Adrenal cortex
Cortisol AldosteroneTestosterone
ACTIONS OF CORTISOL
cortisol
Increases catabolism
blood glucoseincreased
muscle breakdown
plasma proteins
increased
free fatty acids
increased
SNS responseincreased
immune/inflammatory
systemssuppressed
ADRENAL CORTICAL DISORDERS
Adrenal cortical insufficiency: inability to make all three hormones Primary adrenal cortical insufficiency
(Addison disease) Secondary adrenal cortical insufficiency Acute adrenal crisis
Excessive adrenal secretion Glucocorticoid hormone excess (Cushing
syndrome) Hyperaldosteronism
Congenital adrenal hyperplasia Decreased cortisol synthesis; other
hormones may be increased or decreased
CLINICAL MANIFESTATIONS OF ADDISON DISEASE (CHRONIC ADRENAL INSUFFICIENCY)
CLINICAL MANIFESTATIONS OF CUSHING SYNDROME (HIGH LEVELS OF CORTISOL IN THE BLOOD)
SCENARIO
Three men have adrenal problems. One has hypoaldosteronism, one has an
inability to make cortisol, and one has an inability to make testosterone.
Question: Which of them is most likely to develop:
Hypotension? High CRH levels? Hypoglycemia? Hypervirilization? Decreased libido? Hyperkalemia?
SCENARIO
Two women have benign pituitary tumors. One woman has lost weight and
complains of being hot all the time; she presents as thin and nervous, with tachycardia and exophthalmos
The second woman has gained weight in her abdomen and presents with a round face and thin arms and legs with stretch marks; she says that at her last checkup her doctor told her she was prediabetic
Question: What hormones are being secreted by
the pituitary tumors in these patients? Why?
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