342
UNIT 3
Organ Systems
SYNOPSIS 17-1
Pathological Terms for the Endocrine System
Bitemporal hemianopia
: A visual f
eld def cit characterized by loss oF both temporal visual f
elds, most oFten due to com-
pression oF the optic chiasm by a pituitary tumor or cyst (±ig. 17-7A,B).
Goiter
: A general term For enlargement oF the thyroid gland; common causes include benign multinodular goiter, diFFuse
toxic goiter, and thyroiditis (±ig. 17-8C).
Osteitis f
brosa cystica
: A cystic bone lesion seen in patients with hyperparathyroidism due to increased osteoclast activity
and bone resorption caused by elevated parathyroid hormone (±ig. 17-9C).
Polydipsia
: Term describing patients with excessive thirst, commonly seen in diabetes mellitus when hyperglycemia causes
osmotic fl uid diuresis with resultant dehydration and thirst (±ig. 17-16).
Polyuria
: Term describing excessive urination, commonly seen in diabetes mellitus when hyperglycemia produces osmotic
uid diuresis with resultant dehydration and secondary polydipsia (±ig. 17-16).
Amyloid
: Extracellular glycoproteins characterized physically by f
brillar ultrastructures and chemically by response to
special staining reactions (±ig. 17-16).
CLINICAL CORRELATION
Figure 17-16.
Type 2 Diabetes Mellitus.
H&E,
3
195
Type 2 diabetes mellitus
is characterized by
hyperglyce-
mia
with normal or elevated
insulin
levels, in contrast
to
type 1 diabetes
in which hyperglycemia is associated
with little or no insulin production. In type 2 diabetes,
insulin is present, but insulin-sensitive tissues, such as
skeletal muscle and adipose tissues, maniFest resistance
to the action oF insulin. DeFects in
beta cell
Function
also contribute to the disease process. Type 2 diabetes
generally has an insidious onset and typically aFFects
adults. Risk Factors include genetic Factors and a strong
association with obesity. Approximately 85% oF type 2
diabetes is associated with obesity. Clinically, patients
present primarily with
polyuria
and
polydipsia
due to
the hyperglycemia. Chronic hyperglycemia leads to
accelerated atherosclerosis and small vessel damage,
which aFFects the eyes (
retinopathy
), kidneys (
neph-
ropathy
), and nerves (
neuropathy
). Early in the disease,
the islets oF Langerhans become hyperplastic in order
to produce more insulin. Later in the disease, the islets
become atrophic with
amyloid
deposition. Treatment
includes diet modif cation and exercise to induce weight
loss and the use oF oral hypoglycemic medications.
Some patients may require insulin late in the disease
process because oF progressive loss oF beta cells.
Amyloid
replacing
islet of Langerhans
Exocrine
pancreas
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