Unit 4: The Endocrine System, The Heart, and The Blood

Comprehensive vocabulary flashcards covering the anatomy and physiology of the endocrine system, the heart, and blood, based on Unit 4 lecture notes.

Exocrine glands

Glands that secrete products into ducts (tubes) to produce a local effect, such as sweat, oil, and digestive glands.

Endocrine glands

Ductless glands that secrete hormones directly into the bloodstream to affect distant target cells.

Endocrinology

The scientific study of the endocrine system.

Hormone

A chemical produced by the endocrine system that is carried by the blood to alter a body function, typically at a distant target.

Negative feedback

A regulatory mechanism in which the body secretes a hormone to reverse or fix a change in homeostasis.

Positive feedback

A regulatory mechanism in which the body secretes a hormone to strengthen or amplify a change in homeostasis.

Synergistic effect

A hormone interaction in which two hormones work together to produce a stronger effect than either hormone acting alone.

Permissive effect

A hormone interaction in which the presence of a first hormone allows the action of a second hormone.

Antagonistic effect

A hormone interaction in which two hormones produce opposite effects, such as insulin lowering blood sugar while glucagon raises it.

Antidiuretic hormone (ADH)

A hormone produced by the hypothalamus and stored/released by the posterior pituitary that causes water reabsorption in the kidneys and constricts arterioles to raise blood pressure; also known as vasopressin.

Diabetes insipidus

A disorder caused by the hyposecretion of antidiuretic hormone (ADH), characterized by the excretion of large amounts of urine and rapid dehydration.

Oxytocin

A posterior pituitary hormone that stimulates labor contractions in the uterus during childbirth and triggers milk ejection (letdown) in mammary glands.

Acromegaly

A condition caused by the hypersecretion of growth hormone (GH) during adulthood, leading to abnormal thickening of the bones.

Calcitonin

A thyroid hormone that decreases blood calcium levels by increasing calcium uptake into bones.

Parathyroid hormone (PTH)

A hormone secreted by the parathyroid glands that functions to increase blood calcium levels.

Aldosterone

A mineralocorticoid secreted by the adrenal cortex that increases renal reabsorption of $Na^+$ and water, preventing dehydration and raising blood pressure.

Cortisol

A glucocorticoid secreted by the adrenal cortex that regulates metabolism, provides resistance to stress, exerts anti-inflammatory effects, and depresses the immune system in high amounts.

Glucagon

A hormone secreted by pancreatic alpha cells that raises blood glucose levels by stimulating the liver to release stored glucose.

Insulin

A hormone secreted by pancreatic beta cells that lowers blood glucose levels by facilitating glucose uptake into cells and promoting anabolism.

Diabetes mellitus

A metabolic condition marked by the inadequate uptake of glucose from the blood.

Melatonin

A hormone secreted by the pineal gland that helps regulate the body's biological clock and sleep-wake cycles.

Perfusion

The delivery of blood per minute per gram of tissue, ensuring sufficient blood flow to target tissues.

Pericardium

The double membrane that encloses and protects the heart, housing pericardial fluid within its cavity to reduce friction.

Cardiac tamponade

A life-threatening buildup of excess pericardial fluid that compresses the heart and impairs its pumping ability.

Myocardium

The thick middle layer of the heart wall, composed of involuntary, striated, branched cardiac muscle tissue.

Chordae tendineae

Stringlike fibrous cords that anchor the cusps of atrioventricular (AV) valves to papillary muscles, preventing backflow during ventricular contraction.

Coronary artery disease (CAD)

A cardiovascular condition in which atherosclerosis (fatty plaque deposits) in the coronary arteries obstructs blood flow to the heart muscle.

Ischemia

A partial blockage or reduction of blood flow to a tissue or organ, such as the heart.

Myocardial infarction (MI)

A heart attack resulting from the complete obstruction of coronary blood flow, causing damage and death to affected myocardium.

Sinoatrial (SA) node

The primary pacemaker of the heart, located in the right atrium, which initiates the action potentials that cause the atria to contract.

Purkinje fibers

Specialized conducting fibers that rapidly distribute action potentials throughout the ventricular walls to stimulate ventricular contraction.

Bradycardia

An abnormal cardiac rhythm characterized by a resting heart rate that is unusually slow.

Tachycardia

An abnormal cardiac rhythm characterized by a resting heart rate that is unusually fast.

Systole

The contraction phase of a heart chamber during which blood is actively emptied or pumped into another chamber or vessel.

Diastole

The relaxation phase of a heart chamber during which it expands and fills with blood.

Stroke volume

The specific volume of blood pumped out by a ventricle during a single contraction.

Cardiac output

The volume of blood pumped each minute by a ventricle, averaging approximately $5\,\text{L}$ per minute at rest.

Albumin

The most abundant plasma protein, responsible for maintaining fluid balance (osmotic pressure) and transporting substances through the bloodstream.

Hemopoiesis

The physiological process by which stem cells within the red bone marrow produce all formed blood elements; also called hematopoiesis.

Erythropoietin

A hormone produced primarily by the kidneys that stimulates the production of erythrocytes (erythropoiesis) in red bone marrow.

Hemoglobin

An iron-containing, oxygen-transport protein inside erythrocytes, capable of binding up to $4$ molecules of $O_2$.

Diapedesis

The amebalike ability of white blood cells to crawl and squeeze across intact blood vessel walls to reach damaged or infected tissues.

Neutrophils

Phagocytic granular leukocytes with 2 to 5 lobed nuclei and lavender-pink granules that serve as the first responders to sites of infection.

Basophils

Granular leukocytes with blue-purple granules and a two-lobed nucleus that release histamine during inflammation and heparin to prevent clotting.

Monocytes

Agranular leukocytes with horseshoe- or kidney-shaped nuclei that differentiate into phagocytic macrophages to ingest bacteria and cellular debris.

Leukopenia

An abnormal reduction in the total circulating white blood cell count.

Leukemia

A cancer of the red bone marrow characterized by the uncontrolled, abnormal overproduction of white blood cells.

Hemostasis

A three-step physiological mechanism that stops bleeding, consisting of vascular spasm, platelet plug formation, and blood coagulation.

Fibrinolysis

The enzymatic breakdown of a blood clot after tissue repair is complete, carried out by the enzyme plasmin.

Thrombus

An abnormal, stationary blood clot formed within an unbroken, intact blood vessel.

Embolism

An obstruction caused by a dislodged thrombus or foreign mass that travels through the bloodstream and occludes a smaller vessel.

Universal recipient

An individual with blood type AB+, possessing A, B, and Rh antigens, who can safely receive transfusions of red blood cells from any ABO/Rh blood type.

Universal donor

An individual with blood type O-, lacking A, B, and Rh surface antigens, whose red blood cells can be safely donated to all ABO/Rh blood types.