The Endocrine System

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Last modified 07/03/2015

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CHAPTER 6

The Endocrine System

SYSTEMWIDE ELEMENTS

Physiologic Anatomy

1. Definition of a hormone

2. Chemically categorized by physiologic action

3. Hormone receptors

4. Mechanisms of hormone action

5. Feedback control of hormone production (Figure 6-1)

Pituitary Gland

1. Location: Base of the skull in the sphenoid bone; connected to the hypothalamus by the pituitary stalk (infundibulum), which links the nervous and endocrine systems

2. Composition

3. Anterior pituitary hormones

a. GH

b. ACTH

c. TSH

d. Other anterior pituitary hormones under hypothalamic control

4. Posterior pituitary hormones

a. ADH

b. Oxytocin

Thyroid Gland

1. Location: Immediately below the larynx laterally and anterior to the trachea

2. Composition: Two lobes connected by an isthmus

3. Regulation of secretion (thyroid hormones)

4. Physiologic activity

5. Disorders resulting from dysfunction

6. Thyrocalcitonin (calcitonin)

Parathyroid Glands

1. Location: Four glands on the posterior surface of the thyroid gland

2. Composition: Chief cells release PTH

3. Regulation of secretion

4. Physiologic activity

5. Disorders resulting from dysfunction

Adrenal Glands

1. Location: Retroperitoneal, superior to the kidney

2. Composition: Two separate endocrine tissues that produce distinct hormones

3. Cortical hormones

a. Glucocorticoids (cortisol is the major hormone)

i. Regulation of secretion

ii. Physiologic activity

iii. Disorders resulting from dysfunction

b. Mineralocorticoids (aldosterone is the major hormone)

4. Medullary hormones: Epinephrine and norepinephrine

Pancreas

1. Location: Lies transversely behind the peritoneum and stomach

2. Composition: Exocrine and endocrine components. Endocrine functions originate from the islet cells, which constitute less than 2% of the total pancreatic volume; 65% of the islet cells are beta cells, which produce insulin. Glucagon is produced by the alpha cells; somatostatin and gastrin are produced by the delta cells.

3. Insulin

a. Regulation of secretion

b. Physiologic activity

c. Disorders resulting from dysfunction

4. Glucagon

a. Regulation of secretion

b. Physiologic activity

c. Deficient glucagon production is thought to play a role in defective glucose counterregulation in insulin-induced hypoglycemia in type 1 diabetes mellitus

d. Available as a pharmacologic agent to correct insulin-induced hypoglycemia (all diabetics should have a readily available source)

5. Somatostatin

PATIENT ASSESSMENT

1. Nursing history

a. Patient health history

i. Presence of pathophysiologic processes that can result in endocrine dysfunction

ii. Pregnancy, postpartum state

iii. Presence of preexisting chronic endocrine disorder (diagnosed or undiagnosed)

iv. Poor compliance with pharmacologic therapy for a preexisting endocrine disorder

v. Presence of an unrelated critical illness in a patient with a preexisting chronic endocrine disorder

vi. Positive family history of an endocrine disorder

vii. Use of systemic steroids

viii. Indicators of altered health patterns

(a) Cognition and perception

(b) Nutrition and metabolism

(c) Elimination

(d) Activity and exercise

(e) Sleep and rest: Restlessness, inadequate sleep

(f) Sexual function

(g) Roles and relationships

(h) Coping and stress tolerance

(i) Health perception and health management: Evidence of noncompliance with the prescribed medical regimen

b. Family history: Endocrine disorders in other family members

c. Social history

d. Medication history

2. Nursing examination of patient

a. Physical examination data

i. Inspection

ii. Palpation: Enlarged or nodular thyroid gland, often painful

iii. Percussion: Abnormal deep tendon reflexes (may be hyperreflexic or hyporeflexic)

iv. Auscultation

b. Monitoring data

3. Appraisal of patient characteristics

a. Resiliency

b. Vulnerability

c. Stability

d. Complexity

e. Resource availability

f. Participation in care