Endocrine System and Intercellular Communication (Lecture Notes)

Flashcards covering intercellular communication, hypothalamic-pituitary axis, major endocrine glands and hormones, and diabetes mellitus.

What term describes communication that occurs between two cells in physical contact?

Direct communication.

Which type of intercellular communication transfers information from a cell to neighboring cells within the same tissue using chemical messengers?

Paracrine communication.

Which type of intercellular communication affects the same cells that secrete the chemical messengers?

Autocrine communication.

What is endocrine communication?

Chemical messengers (hormones) travel in the blood to distant target cells and have receptors for the hormone.

Endocrine vs Nervous communication: which is typically slower and longer lasting and uses hormones?

Endocrine system.

Which system is typically faster and short-lived and uses neurotransmitters?

Nervous system.

What are hormones responsible for regulating in the body?

Growth and development, reproduction, metabolism and energy balance, body water and electrolyte/nutrient levels, and mobilization of body defenses.

What is the endocrine system?

Endocrine cells, tissues, and organs that produce hormones.

Where do endocrine glands release secretions?

Into the extracellular fluid (blood).

Where do exocrine glands release secretions?

Onto epithelial surfaces via ducts.

Where is the pituitary gland located?

Within the sella turcica, inferior to the hypothalamus, connected by the infundibulum.

Which pituitary lobe is controlled by the hypothalamus and secretes hormones that regulate other endocrine glands?

Anterior lobe (adenohypophysis).

What are the parts of the anterior pituitary mentioned?

Pars tuberalis, pars distalis, pars intermedia.

Which pituitary lobe stores and releases hormones produced by the hypothalamus (e.g., ADH and oxytocin)?

Posterior lobe (neurohypophysis).

How does the hypothalamus regulate the pituitary?

Through the hypophyseal portal system and regulatory hormones (releasing and inhibiting hormones).

What are the two types of hypothalamic regulatory hormones and their general roles?

Releasing hormones stimulate secretion from the anterior lobe; inhibiting hormones prevent secretion; secretion is controlled by negative feedback.

Which anterior pituitary hormone stimulates thyroid hormone release?

Thyroid-stimulating hormone (TSH or thyrotropin).

Which hypothalamic hormone stimulates ACTH release from the anterior pituitary?

Corticotropin-releasing hormone (CRH).

Which hormone stimulates prolactin release from the anterior pituitary?

Prolactin-releasing hormone (PRH).

Which hormone inhibits prolactin release?

Prolactin-inhibiting hormone (PIH).

Which hormones regulate growth hormone release?

Growth hormone-releasing hormone (GH-RH) and growth hormone-inhibiting hormone (GH-IH).

Which anterior pituitary hormone stimulates milk production?

Prolactin (PRL).

What hormones are released by the posterior pituitary and what are their actions?

Oxytocin (uterine contractions and milk ejection) and antidiuretic hormone (ADH; promotes water retention).

What stimulates the thyroid gland and what do T3 and T4 do?

TSH stimulates release; T3 and T4 increase metabolic rate, oxygen consumption, and BP/HR; activate genes for energy use.

What does calcitonin do?

Lowers blood calcium by increasing calcium excretion in kidneys and decreasing calcium absorption in the digestive tract.

Where are parathyroid glands located and what do they secrete?

Four glands on the posterior surface of the thyroid; principal cells secrete parathyroid hormone (PTH) to raise blood calcium.

Which adrenal cortex zone secretes mineralocorticoids like aldosterone?

Zona glomerulosa.

Which adrenal cortex zone secretes glucocorticoids like cortisol?

Zona fasciculata.

Which adrenal cortex zone secretes androgens?

Zona reticularis.

What does the adrenal medulla release upon sympathetic stimulation?

Catecholamines: epinephrine and norepinephrine.

What is the pineal gland's function?

Melatonin synthesis from serotonin; influences circadian rhythm.

Where is the pancreas located and what are its endocrine components?

Lies in the loop between the stomach and small intestine; contains pancreatic islets (endocrine) and acini (exocrine).

Which pancreatic cells produce insulin and glucagon?

Beta cells produce insulin; alpha cells produce glucagon.

What is the role of insulin?

Released in response to high blood glucose; lowers glucose by promoting uptake into cells.

What is the role of glucagon?

Released in response to low blood glucose; raises glucose by promoting liver glucose release.

What are the classic signs of diabetes mellitus?

Hyperglycemia, glycosuria, and polyuria.

What characterizes Type 1 diabetes mellitus?

Inadequate insulin production by pancreatic beta cells; requires daily injections; usually in children/young adults.

What characterizes Type 2 diabetes mellitus?

Most common form; insulin resistance; obesity; managed with weight loss and medications.