Endocrine System: Growth Hormone, Prolactin, and Posterior Pituitary Hormones

Flashcards testing concepts on growth hormone, prolactin, oxytocin, antidiuretic hormone (ADH), and their corresponding endocrinopathies based on the lecture transcript.

How does growth hormone affect blood glucose levels and liver metabolic processes?

Growth hormone increases blood glucose levels by stimulating gluconeogenesis (glucose synthesis) and glycogenolysis (glycogen breakdown) in the liver while decreasing glucose uptake in peripheral tissues.

What is the general categorization of growth hormone regarding its anabolic and catabolic actions?

Growth hormone is anabolic toward proteins, and catabolic toward carbohydrates (sugars) and fats.

What hormone mediates most of the growth-promoting effects of growth hormone on bones, skeletal muscle, and organs?

Insulin-like Growth Factor 1 (IGF-1).

How do gigantism and acromegaly differ with respect to the timing of excess growth hormone secretion?

Gigantism occurs when excess growth hormone is produced during childhood or adolescence while the individual is still developing, whereas acromegaly occurs when excess growth hormone production begins during adulthood.

What physical signs and symptoms are characteristic of acromegaly?

Organ hypertrophy (enlarged heart and liver), enlarged hands and feet, soft tissue changes in the face, a prominent forehead, and glossomegaly (enlargement of the tongue).

Through what surgical path can pituitary tumors (adenomas) be removed as described in the lecture?

Surgeons go through the nasal cavity, punch through the back wall of the sphenoid bone into the sphenoid sinus, and pop out into the sella turcica.

What physiological factors and conditions stimulate prolactin secretion?

Increased estrogen levels, infant suckling, pregnancy, stress, and sleep.

What neurochemical acts as Prolactin Inhibiting Hormone (PIH)?

Dopamine.

How does the hypothalamus tonically control prolactin release under baseline conditions?

The hypothalamus tonically (constantly) releases dopamine (PIH), which inhibits the anterior pituitary from releasing prolactin.

What are the complementary roles of prolactin and oxytocin in lactation?

Prolactin stimulates milk synthesis (lactogenesis), while oxytocin stimulates myoepithelial cells to squeeze the glands and eject milk (milk letdown reflex).

How are gynecomastia and galactorrhea defined?

Gynecomastia is inappropriate mammary tissue growth in males and females, whereas galactorrhea is inappropriate milk synthesis and secretion.

Where are posterior pituitary hormones produced and how do they reach the posterior pituitary?

They are synthesized in neuron cell bodies within nuclei of the hypothalamus and transported down axons through the hypothalamic-hypophyseal tract in the infundibulum to be secreted from the posterior pituitary.

Which specific hypothalamic nuclei synthesize oxytocin and antidiuretic hormone (ADH)?

The paraventricular nucleus synthesizes oxytocin, and the supraoptic nucleus synthesizes antidiuretic hormone (ADH).

How does the positive feedback loop function during childbirth via oxytocin?

The fetus pressing on the cervix sends action potentials to the hypothalamus to release oxytocin from the posterior pituitary, triggering uterine smooth muscle contractions that push the fetus harder against the cervix, repeating the cycle.

What physiological change triggers osmoreceptors to stimulate ADH secretion?

An increase in blood osmolarity (an increased concentration of solutes per unit volume of liquid).

How does antidiuretic hormone (ADH) affect the kidneys and blood pressure?

ADH targets the distal convoluted tubules and collecting ducts of the kidneys to conserve water, increasing circulating blood volume and elevating hydrostatic blood pressure.

What causes diabetes insipidus and what are its primary symptoms?

Diabetes insipidus is caused by a lack or deficiency of ADH, resulting in the production of high volumes of extremely dilute urine and chronic thirst.

What is Syndrome of Inappropriate ADH Secretion (SIADH), and what clinical features does it cause?

SIADH is caused by excess ADH secretion, leading to excessive water retention, increased extracellular fluid volume, edema, and hyponatremia (low salt concentration relative to blood fluid volume).