Pathophysiology of Endocrine System

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Questions and Answers

What percentage of the pancreas mass is occupied by islets of Langerhans?

5-10%

2-3% (correct)

20-25%

10-15%

What is the leading cause of end-stage renal disease?

Atherosclerosis

Hypertension

Hyperlipidemia

Diabetes mellitus (correct)

What is the term for elevated blood sugar that does not reach the criterion for diabetes?

Prediabetes (correct)

Insulin resistance

Diabetes mellitus

Hyperglycemia

What are the two main hormones produced by the pancreas that regulate glucose metabolism?

Insulin and glucagon Signup and view all the answers

What is the approximate number of new diabetes cases diagnosed in the USA each year?

800,000 Signup and view all the answers

What is the term for the modification of blood supply to the islets of Langerhans?

Modified blood supply Signup and view all the answers

What is the term for the chronic high blood sugar levels associated with diabetes?

Hyperglycemia Signup and view all the answers

What is a risk factor for developing diabetes mellitus?

Abdominal obesity Signup and view all the answers

What is the primary function of the endocrine system?

To regulate target organ function through chemical messengers Signup and view all the answers

What is the term for the state of steady conditions vital for life?

Homeostasis Signup and view all the answers

Which of the following glands is NOT part of the endocrine system?

Liver Signup and view all the answers

What is the term for excess activity of a specific hormone or hormones?

Hypersecretion Signup and view all the answers

What is the term for reduced activity of a specific hormone or hormones?

Hyposecretion Signup and view all the answers

What is the term for when a tissue no longer responds to a specific hormone?

Altered responsiveness Signup and view all the answers

What is unique about the pancreas?

It is both an endocrine and exocrine gland Signup and view all the answers

Which of the following is an example of an endocrine disorder?

Type 1 diabetes Signup and view all the answers

What is the primary cause of islet destruction in type 1 diabetes?

Immune effector cells reacting against endogenous beta cell antigens Signup and view all the answers

What is the fundamental immune abnormality in type 1 diabetes?

Failure of self-tolerance in T cells specific for beta cell antigens Signup and view all the answers

What is detected in the blood of 70% to 80% of patients with type 1 diabetes?

Autoantibodies against beta cell antigens Signup and view all the answers

What is the primary characteristic of type 2 diabetes?

Heterogeneous and multifactorial complex disease Signup and view all the answers

What are the two defects that characterize type 2 diabetes?

Insulin resistance and beta cell dysfunction Signup and view all the answers

What is the consequence of insulin resistance in type 2 diabetes?

Compensatory beta cell hyperfunction Signup and view all the answers

What is the role of environmental factors in the development of type 2 diabetes?

They play a significant role Signup and view all the answers

What is the concordance rate of type 2 diabetes in monozygotic twins?

80% to 90% Signup and view all the answers

What is a chronic complication of diabetes mellitus caused by nonenzymatic glycation?

Retinopathy Signup and view all the answers

What is the most common cause of death in diabetes mellitus?

Myocardial Infarction Signup and view all the answers

What is the definition of hypoglycemia in terms of blood sugar level?

Below 70 mg/dL Signup and view all the answers

What is a symptom of neurogenic hypoglycemia?

Diaphoresis Signup and view all the answers

What is a chronic complication of diabetes mellitus caused by osmotic damage?

Cataracts Signup and view all the answers

What is the sequence of metabolic derangements leading to diabetic coma in type 1 diabetes mellitus?

Absolute insulin deficiency, ketoacidosis, severe volume depletion Signup and view all the answers

What is a symptom of neuroglycopenic hypoglycemia?

Altered mental status Signup and view all the answers

What is a general weakness of diabetes mellitus?

Poor wound healing Signup and view all the answers

What is the definition of insulin resistance?

The failure of target tissues to respond normally to insulin Signup and view all the answers

What is the effect of insulin resistance on the liver?

It fails to inhibit endogenous glucose production Signup and view all the answers

What is the effect of insulin resistance on skeletal muscle?

It abnormally decreases glucose uptake and glycogen synthesis Signup and view all the answers

What is the effect of insulin resistance on adipose tissue?

It fails to inhibit hormone-sensitive lipase Signup and view all the answers

What is the compensatory response of pancreatic β cells to insulin resistance?

Hypersecretion of insulin Signup and view all the answers

What is the eventual outcome of β cell compensation to insulin resistance?

β cell failure and diabetes Signup and view all the answers

What are the three P's associated with acute manifestations of diabetes?

Polydipsia, Polyuria, Polyphagia Signup and view all the answers

What is a rare cause of diabetes?

Unopposed secretion of growth hormone and epinephrine Signup and view all the answers

Study Notes

The Endocrine System

The endocrine system works through chemical messengers (hormones) that are secreted directly into the circulatory system to regulate target organ function.
The feedback loop controls the release of hormones and maintains homeostasis, a state of steady conditions vital for life.
The endocrine system consists of various glands, including the pineal gland, thalamus/hypothalamus, pituitary gland, thyroid and parathyroid, thymus, adrenal gland, pancreas, uterus, ovaries, and testes.

Endocrine Disorders

Endocrine disorders can be categorized into three main types:
- Hypersecretion: excess activity of a specific hormone or hormones, which can be caused by overproduction of a hormone, glandular hypertrophy/hyperplasia, or tumors that secrete hormones.
- Hyposecretion: reduced activity of a specific hormone or hormones, which can be caused by atrophy of glandular tissue, damage from autoimmune attack, infection, or neoplasia, or reduced hormonal stimulation of a gland.
- Altered responsiveness of a tissue to a specific hormone, which can involve down-regulation of receptors or altered receptor/secondary messenger function.

Pancreas

The pancreas is both an exocrine and endocrine gland.
The endocrine cells, referred to as the islets of Langerhans, are small clusters scattered throughout the pancreas, surrounded by exocrine cells.
The islets of Langerhans make up only 2%–3% of the mass of the pancreas, but receive 5–10 times more blood than the exocrine pancreas.
The pancreas produces hormones that regulate glucose metabolism, including insulin and glucagon.

Diabetes Mellitus

Diabetes mellitus is a group of metabolic disorders characterized by hyperglycemia.
Hyperglycemia results from defects in insulin secretion, insulin action, or both.
Diabetes mellitus is associated with secondary damage in multiple organ systems, especially the kidneys, eyes, nerves, and blood vessels.
Prediabetes is defined as elevated blood sugar that does not reach the criterion for an outright diagnosis of diabetes.
Prediabetes is associated with obesity, dyslipidemia, and hypertension.

Pathogenesis of Type 1 Diabetes

Type 1 diabetes is an autoimmune disease in which islet destruction is caused primarily by immune effector cells reacting against endogenous beta cell antigens.
The fundamental immune abnormality in type 1 diabetes is a failure of self-tolerance in T cells specific for beta cell antigens.
Autoantibodies against beta cell antigens, including insulin and glutamic acid decarboxylase, are detected in the blood of 70% to 80% of patients.

Pathogenesis of Type 2 Diabetes

Type 2 diabetes is a heterogeneous and multifactorial complex disease that involves interactions of genetics, environmental risk factors, and inflammation.
The two defects that characterize type 2 diabetes are:
- A decreased ability of peripheral tissues to respond to insulin (insulin resistance).
- Beta cell dysfunction that is manifested as inadequate insulin secretion in the face of insulin resistance and hyperglycemia.
Insulin resistance predates the development of hyperglycemia and usually is accompanied by compensatory beta cell hyperfunction and hyperinsulinemia in the early stages of the evolution of diabetes.

Acute Manifestations

Polydipsia, polyuria, and polyphagia (3 P’s).
Weight loss.
Diabetic ketoacidosis (DKA) in type 1 diabetes.
Hyperosmolar hyperglycemic state in type 2 diabetes.
Rarely, can be caused by unopposed secretion of growth hormone (GH) and epinephrine, or in patients on glucocorticoid therapy (steroid diabetes).
General weakness, skin sepsis, and poor wound healing.

Chronic Complications

Nonenzymatic glycation:
- Small vessel disease (hyaline arteriolosclerosis, retinopathy, neuropathy, nephropathy).
- Large vessel disease (atherosclerosis, CAD, cerebrovascular disease, peripheral vascular disease).
Osmotic damage (sorbitol accumulation in organs with aldose reductase and or absent sorbitol dehydrogenase):
- Neuropathy: motor, sensory, and autonomic degeneration.
- Cataracts.

Hyperglycemic Emergencies

Sequence of metabolic derangements leading to diabetic coma in type 1 diabetes:
- Absolute insulin deficiency leads to a catabolic state, eventuating in ketoacidosis and severe volume depletion.
- These derangements bring about sufficient central nervous system compromise to cause coma and eventually death if left untreated.

Hypoglycemia in Diabetes Mellitus

Hypoglycemia: a blood sugar level below 70 milligrams per deciliter (mg/dL) or 3.9 millimoles per liter (mmol/L).
Usually occurs in patients treated with insulin or insulin secretagogues (e.g., sulfonylureas, meglitinides) in the setting of high-dose treatment, inadequate food intake, and/or exercise.
Neurogenic (autonomic-sympathetic activation) symptoms: diaphoresis, tachycardia, tremor, anxiety, hunger.
Neuroglycopenic symptoms: altered mental status, seizures, death due to insufficient glucose in CNS.
Behavioral symptoms: may occur in the absence of preceding neurogenic symptoms in patients with attenuated autonomic response (hypoglycemia unawareness).

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Description

This quiz covers the pathophysiology of the endocrine system, including the role of hormones, feedback loops, and homeostasis.