Endocrine System Flashcards//STUDIED

Flashcards for Endocrine System Lecture Review

Endocrine System

Provides long-term regulation, slower response that lasts longer, regulates long-term processes such as growth, maturation, and reproduction.

Direct Communication

Occurs between two cells of the same type in extensive physical contact; cells function as a single entity (gap junctions in heart muscle).

Paracrine Communication

Involves the release and receipt of chemical signals; transfer of information from cell to cell within a single tissue.

Endocrine Communication

Involves the release of hormones into the bloodstream for long-distance communication affecting many tissues and organs.

Target Cells

Specific cells that have receptors needed to bind and 'read' the hormonal message.

Amino Acid Derivatives

Small molecules structurally related to amino acids synthesized from tyrosine and tryptophan; examples include thyroid hormones, epinephrine, and melatonin.

Peptide Hormones

Chains of amino acids; examples include insulin, thyroid-stimulating hormone, and growth hormone.

Eicosanoids

Lipid derivatives important in paracrine communication, including leukotrienes and prostaglandins.

Steroid Hormones

Lipid derivatives derived from cholesterol; examples include sex hormones and corticosteroids.

First Messenger

The hormone itself as it binds to its specific receptor on the cell membrane.

Second Messenger

Appearance is triggered by the binding of the first messenger; the most common is cyclic-AMP, which causes changes in cell metabolism.

Simple Endocrine Reflex

Involves only one hormone.

Complex Endocrine Reflexes

Involve one or more intermediate steps and two or more hormones.

Hypothalamus

Represents the highest level of endocrine control, integrating endocrine and nervous system activities.

Releasing Hormones (RH)

Cause the release of pituitary hormones.

Inhibiting Hormones (IH)

Inhibit the release of pituitary hormones.

Thyroid Stimulating Hormone (TSH)

Triggers the release of thyroid hormones by the thyroid gland.

Adrenocorticotropic Hormone (ACTH)

Stimulates the release of steroid hormones by the adrenal cortex.

Follicle Stimulating Hormone (FSH)

Stimulates follicle development and estrogen secretion in females; stimulates sperm production in males.

Luteinizing Hormone (LH)

Stimulates ovulation and progesterone secretion in females; stimulates testosterone secretion in males.

Prolactin (PRL)

Stimulates development of mammary glands and milk production.

Growth Hormone (GH)

Stimulates cell growth and division by increasing protein synthesis; major target tissues are muscle and bone.

Antidiuretic Hormone (ADH)

Decreases the amount of water lost at the kidneys.

Oxytocin

Causes milk ejection (milk letdown) and uterine contractions during labor.

Triiodothyronine (T3)

Thyroid hormone containing three iodine molecules.

Thyroxine (T4)

Thyroid hormone containing four iodine molecules; the most common form.

Calcitonin

Hormone produced by C-cells of the thyroid gland that helps regulate calcium concentrations in body fluids.

Parathyroid Hormone (PTH)

Primary regulator of blood calcium levels, increases calcium levels.

Aldosterone

Adrenal cortex hormone that causes sodium reabsorption at the kidneys.

Cortisol (Hydrocortisone)

Adrenal cortex hormone that increases glucose synthesis and glycogen formation in the liver and has anti-inflammatory properties.

Epinephrine and Norepinephrine

Hormones produced by the adrenal medulla that increase muscle strength, release fats, cause glycogen breakdown, and increase heart rate.

Melatonin

Hormone synthesized by the pineal gland that is responsible for our sleep/wake cycles or circadian rhythm.

Insulin

Hormone secreted by beta cells in the pancreatic islets that stimulates glucose transport across cell membranes, decreasing blood glucose.

Glucagon

Hormone secreted by alpha cells in the pancreatic islets that stimulates the breakdown of glycogen and triglycerides, increasing blood glucose.

Calcitriol

Hormone produced by the kidneys that stimulates phosphate and calcium absorption along the digestive tract.

Erythropoietin (EPO)

Hormone produced by the kidneys that stimulates RBC production by the bone marrow.

Renin

Enzyme produced by the kidneys that starts a cascade of reactions leading to water retention and increased blood pressure.

Natriuretic Peptides

Hormones produced by endocrine cells in the heart that result in decreased blood volume and blood pressure.

Thymosins

Hormones produced by the thymus that play a role in developing and maintaining normal immune defenses.

Leptin

Hormone produced by adipose tissue that acts as a feedback control for appetite.

Antagonistic Effect

Opposing effect, such as insulin and glucagon.

Synergistic Effect

Additive effect, such as parathyroid hormone and calcitriol.

General Adaptation Syndrome (GAS)

Our response to stress, divided into the alarm phase, resistance phase, and exhaustion phase.

Alarm Phase

First phase of GAS, mediated by epinephrine from the adrenal medulla, mobilizes energy reserves for 'fight or flight'.

Resistance Phase

Second phase of GAS, mainly mediated by the adrenal cortex through release of cortisol and aldosterone, conserves glucose, salts, and water.

Exhaustion Phase

Third phase of GAS, begins when homeostatic mechanisms break down, leading to organ system failure.