Physiology Lecture 23 – Endocrinology I

Set of vocabulary flashcards covering key terms and definitions related to Endocrinology and Neurophysiology as discussed in the lecture.

Pineal gland

Produces melatonin, regulating circadian rhythms.

Posterior pituitary gland

Releases oxytocin (milk ejection, labor, social behavior) and vasopressin (water reabsorption).

Anterior pituitary gland

Secretes multiple hormones including prolactin (milk production), growth hormone (growth and metabolism), ACTH (cortisol release), TSH (thyroid hormone synthesis), and gonadotropins (FSH, LH for gamete production).

Thyroid gland

Produces thyroid hormones (T3 and T4) for metabolism, growth, and calcitonin to lower blood calcium levels.

Parathyroid gland

Secretes parathyroid hormone (PTH) which increases blood calcium levels.

Liver

Produces angiotensinogen and insulin-like growth factors (IGF-1), regulating blood pressure and growth.

Pancreas

Regulates glucose metabolism through insulin (lowers glucose) and glucagon (raises glucose), and somatostatin (inhibits gastric acid secretion).

Adrenal cortex

Secretes aldosterone (sodium and potassium homeostasis), cortisol (stress response), and androgens (female sex drive).

Adrenal medulla

Produces epinephrine and norepinephrine for fight-or-flight responses.

Testes

Produces androgens (testosterone and DHT) for sperm production and secondary sexual characteristics.

Ovaries

Produces estrogen, progesterone, and inhibin for egg production and secondary sexual characteristics.

Hypothalamus

Regulates anterior pituitary secretion with neurohormones and directs secretion through the posterior pituitary.

Thymus gland

Involved in lymphocyte cell development.

Hydrophilic hormones

Peptide hormones that exit cells via exocytosis, dissolve in plasma, and have receptors on cell membranes.

Hydrophobic hormones

Steroid hormones that use simple diffusion to exit cells and require transport proteins in blood, with receptors in cytosol or nucleus.

Cortisol

Suppresses immune system, increases glucose production in liver, breaks down proteins, and mobilizes fats.

Anabolic hormones

Hormones like growth hormone that build up tissues in the body.

Absolute refractory period

A period during which a second action potential cannot be generated, regardless of stimulus strength.

Relative refractory period

A period following the absolute refractory period where a stronger than normal stimulus can trigger an action potential.

Atrial Natriuretic Peptide (ANP)

A hormone secreted by the heart (atria) that helps to lower blood pressure by promoting the excretion of sodium and water by the kidneys (natriuresis and diuresis).

Erythropoietin (EPO)

A hormone produced primarily by the kidneys that stimulates the bone marrow to produce red blood cells (erythropoiesis).

Renin

An enzyme (and hormone) secreted by the kidneys that initiates the Renin-Angiotensin-Aldosterone System (RAAS), which plays a key role in regulating blood pressure, blood volume, and electrolyte balance.

Negative Feedback Loop (Endocrinology)

A common regulatory mechanism in hormone systems where the output or product of a process inhibits a step earlier in the pathway, thereby reducing the activity of the pathway and maintaining hormone levels within a specific range.

Demyelination

The process of losing the myelin sheath that insulates nerves, leading to impaired nerve impulse conduction, as observed in neurological conditions like Multiple Sclerosis.

Saltatory Conduction

The rapid propagation of action potentials along myelinated axons, where the electrical signal 'jumps' from one Node of Ranvier to the next, significantly increasing conduction velocity.