Endocrine
Core Concepts and Objectives with Advanced Organizers
Endocrine Anatomy and Physiology
Analyze the anatomy and physiology of the endocrine system:
1. Examine the production and action of hormones produced by the thyroid, pancreas, and
adrenal glands.
Thyroid:
T4 (90%):
1. Released by thyroid gland converted to T3 inside of cell prior to entering nucleus
T3 (10%):
1. more potent, actions are short-lived, present in blood in much smaller amounts than T4
2. stimulates production of the contractile protein a-myosin heavy chain in the heart
3. stimulation production of sarcolemma ion pumps (Na+-K+ ATPase pump, Ca++ ATPase
pump) and B-adrenergic receptors
4. hyperthyroidism ↑ HR/CO cardiomyopathy
o both T3 and T4 are bound to either albumin or thyroxin-binding globulin in
the blood that act as transport proteins release hormones once they reach
their target cells
o both T3 and T4 are stored as thyroglobulin, which is a precursor for both
hormones
there is enough stored hormone to last 2-3 mos person can have
failing thyroid for 2-3 mos before manifestations appear
o ↓ T3/T4 ↑ thyroid-releasing factor ↑ TSH ↑ T3/T4
5. T3/T4 Functions:
o Maintenance of muscle tone
o Skeletal muscle maturation
o Antagonization of insulin
o Regulation of cellular metabolism
o Promotion of production of heat
o Maintenance of cardiac output, contraction, and rate
o Maintenance of GI secretion
o Assistance w/ Ca mobilization and stimulation of lipid metabolism
o Free fatty acid release
o Cholesterol synthesis
o RBC production
o Affects respiratory rate/O2 utilization
thyroxine:
1. formed w/ iodine
o take approx. 1mg/wk to produce thyroxine
o iodides used for making thyroxine are trapped by thyroid gland
o uptake of iodine regulated by TSH
, calcitonin:
1. secreted by C-cells of the thyroid
2. blocks osteoclastic activity prevents bone resorption effects of PTH, prostaglandins,
and calciferols ↓ serum Ca
3. ↓ GI absorption of Ca and phos ↓ serum phos
Pancreas:
Alpha cells:
1. Secrete glucagon
Beta cells:
1. Secrete gastrin
Delta cells:
1. Secrete gastrin and somatostatin
F cells:
1. Secrete pancreatic polypeptide stimulates secretion of gastric acid and inhibits
cholecystokinin secretion
Adrenal:
2. Discuss the effects of aging on the thyroid gland, adrenal gland and the pancreas.
Thyroid:
Undergoes atrophy and fibrosis
Inflammation/nodularity
S/S of thyroid disease are more occult in elderly pts
↑ TSH secretion
Pancreas:
↓ beta cell function glucose intolerance or diabetes
↓ pancreatic cell regeneration
Adrenal gland:
Develops fibrous tissue after 50 yrs old
↓ ability to clear glucocorticoids
↓ cortisol used as we age
↓ clearance/use of cortisol ↑ circulating cortisol
↓ growth hormone ↓ muscle size and function, ↓ fat/bone mass, and changes in
reproductive/cognitive function
↑ PTH ↑ mortality in the elderly
↓ vit. D osteoporosis, CA, autoimmune d/o, diabetes, CVD, and mental health d/o
Examine the pathologic basis of adult and pediatric disorders which affect the
endocrine system:
Obesity
3. Explain the pathologic basis and consequences of obesity in the adult and child.
Metabolic d/o ↑ body adipose tissue
Occurs when caloric intake > caloric expenditure
BMI > 30kg/m2
5th leading cause of death in U.S.
↑ risk for:
, 1. HTN
2. Stroke
3. HLD
4. Cholelithiasis
5. Fatty liver
6. GERD
7. Hiatal hernia
8. Osteoarthritis
9. Infectious disease
10. Asthma
11. OSA
12. CKD
13. May ↓ mortality in elderly
Risk factors:
1. Genetic predisposition
2. Metabolic d/o:
o Cushing’s disease
o PCOS
o GH deficiency
o Hypothyroidism
o Hypothalamic injury
3. Socioeconomic factors (↑/↓ income)
4. Food intake
5. Physical inactivity
Patho:
↑ size/number of white adipose tissue (WAT) ↑ stored triglycerides and secretion of
adipokines
Adipokines and other hormones:
1. Regulate food intake and metabolism
2. ↑/↓ fat mass
3. Provide signals to hypothalamus, brainstem, ANS, and hunger center regulate satiety
and energy balance
Visceral WAT dysfunction in regulatory signaling center complications associated
w/ obesity
Hypothalamus regulates food intake and energy balance by regulating neurons that ↑/↓
appetite
GI tract releases adipokines and hormones that interact w/ brain tissue-gut-brain
axis:
1. Leptin:
o Produced by obesity gene (Ob gene)
o ↑ levels ↓ appetite by blocking neurons that ↑ appetite and stimulating
neurons that ↓ appetite
o ↓ levels ↑ appetite and ↓ energy use
o ↑ adipocyte numbers ↑ leptin ineffective at decreasing appetite (leptin
resistance) overeating and weight gain, hyperglycemia, ↑ insulin secretion,
HLD, and ↑ release of proinflammatory mediators