Endocrine System Exam Study Guide Flashcards

Practice flashcards covering the endocrine system, including gland functions, hormone mechanisms, and specific physiological responses.

What is the definition of an endocrine gland?

A ductless gland that releases hormones directly into the bloodstream, typically located near large blood vessels for fast distribution.

Which glands are listed as the main endocrine glands in the notes?

Pituitary, Pineal, Thyroid, Parathyroids, Thymus, Adrenal (Suprarenal), Pancreas, and Gonads.

Explain the lock-and-key model in the context of the endocrine system.

Hormones act as the "key" and receptors act as the "lock"; hormones only affect target cells that have specific matching receptors.

Why does Thyroid Stimulating Hormone (TSH) only act on the thyroid gland?

Because the thyroid is the only tissue that possesses TSH receptors.

How do the Hypothalamus and Pituitary differ in their functional roles?

The Hypothalamus is "the boss" that controls the system by producing releasing or inhibiting hormones; the Pituitary is "the workhorse" that executes orders by releasing hormones into the blood.

What is the sequence of events for thyroid hormone production beginning at the hypothalamus?

Hypothalamus releases TRH (Thyrotropin-Releasing Hormone) $\rightarrow$ Pituitary releases TSH $\rightarrow$ Thyroid produces $T_3$ and $T_4$.

Where is the pituitary gland (hypophysis) located?

It is located in the sella turcica, which is part of the sphenoid bone.

Why is the pituitary gland referred to as the "Master Gland"?

It is called the "Master Gland" because it controls many other endocrine glands.

Describe the structural and functional differences between the two lobes of the pituitary.

The Anterior pituitary is larger and produces 6 hormones; the Posterior pituitary is smaller and only stores and releases ADH and Oxytocin (which are made by the hypothalamus).

What are the six hormones produced by the Anterior Pituitary?

GH (Growth Hormone), Prolactin (PRL), TSH, ACTH, FSH, and LH (or ICSH in men).

What is the function of GH (Growth Hormone)?

It stimulates bone and muscle growth.

What is the function of Prolactin (PRL)?

It stimulates breast milk production.

What are the roles of FSH and LH/ICSH in the endocrine system?

FSH stimulates follicle growth/estrogen in women and sperm production in men. LH/ICSH stimulates ovulation/progesterone in women and testosterone production via Leydig cells in men.

What is the function of ADH (Antidiuretic Hormone / Vasopressin)?

It increases water reabsorption in the kidney tubules, which increases blood volume and potentially blood pressure.

What are the two primary functions of Oxytocin?

It contracts the uterus (helping it return to size after birth) and causes milk ejection during breastfeeding.

What is the difference between calcium resorption and reabsorption?

Resorption is the release of calcium from bone into the blood ("resorption is release"); Reabsorption is the recovery of calcium by the kidney back into the blood instead of excreting it in urine.

How does PTH (Parathyroid Hormone) regulate blood calcium levels?

When blood calcium is low, PTH increases bone resorption and increases kidney reabsorption of calcium to raise blood calcium levels.

What is the function of Aldosterone, the main mineralocorticoid?

It reabsorbs sodium ($Na^+$) and excretes potassium ($K^+$) in urine; water follows the sodium to increase total water reabsorption.

What are the functions of glucocorticoids like Cortisol and Cortisone?

They increase blood glucose levels and provide anti-inflammatory effects.

What is the difference between Glucose and Glycogen?

Glucose is the body's immediate energy source; Glycogen is the storage form of glucose found in the liver and muscles.

Why is the Pancreas classified as both an exocrine and endocrine gland?

It is exocrine because it produces digestive juices delivered via ducts, and endocrine because the Islets of Langerhans release hormones like insulin and glucagon directly into the blood.

What are the roles of Alpha and Beta cells in the Pancreas?

Alpha cells produce Glucagon to increase blood glucose; Beta cells produce Insulin to decrease blood glucose.

How should hypoglycemia be managed in an unconscious patient?

Give nothing by mouth (choking risk); instead, administer a glucagon injection or IV dextrose if available.