Endocrine and Circulatory Systems Overview

A collection of vocabulary flashcards covering key concepts from the endocrine, circulatory, and lymphatic systems.

Hormones

Chemical messengers secreted into the blood to reach specific target cells.

Target Cells

Specific cells that possess receptors for a particular hormone.

Hypothalamus

The brain region that coordinates all activity of the pituitary gland.

Anterior Pituitary

A true endocrine gland that secretes 7 hormones (TSH, hGH, ACTH, FSH, LH, PRL, MSH).

Posterior Pituitary

An extension of the central nervous system that secretes ADH and Oxytocin.

Antidiuretic Hormone (ADH)

Hormone from the posterior pituitary that decreases urine output.

Oxytocin

Hormone that assists in labor, delivery, and reproductive processes.

Thyroid Gland

Located on the anterior trachea; requires Iodine to produce Thyroxine to increase metabolism.

Goiter

A physical enlargement of the thyroid gland often resulting from iodine deficiency or dysfunction.

Parathyroid Hormone (PTH)

Monitors and regulates calcium levels in the blood.

Thymus

Plays a major role in the immune response from childhood until puberty.

Adrenal Cortex

The outer layer of the adrenal gland that secretes vital steroid hormones.

Adrenal Medulla

The inner layer of the adrenal gland that secretes Epinephrine and Norepinephrine.

Pancreatic Alpha Cells

Produce glucagon to increase blood glucose levels.

Pancreatic Beta Cells

Produce insulin to lower blood glucose levels.

Androgens

Male reproductive hormones (like testosterone) produced in the testes.

Estrogens

Female reproductive hormones produced in the ovaries for oocyte maturation.

Pineal Gland

Produces melatonin to regulate sleep/wake cycles.

Hematocrit

The percentage of whole blood volume made up of formed elements (mostly RBCs).

Hemoglobin

The molecule within RBCs that bonds to oxygen and CO2.

Rouleau

A single-file stack of red blood cells that allows passage through small capillaries.

Neutrophils

The most common white blood cell and usually the first to arrive at an injury site.

Monocytes

Leukocytes that function as free macrophages.

Platelets

Cell fragments shed from megakaryocytes used for blood clotting.

Chemotaxis

The process where WBCs are attracted to a specific chemical stimulus at an injury site.

Red Bone Marrow

The primary location for blood cell formation.

Sickle Cell Disease

A condition where RBCs become misshapen, hindering oxygen transport.

Hemophilia

A disorder where the blood does not clot normally.

flow of blood through heart

1. Right Atrium: Deoxygenated blood returns from the body via the superior and inferior vena cava into the right atrium.

2. Right Ventricle: Blood passes through the tricuspid valve into the right ventricle.

3. Pulmonary Artery: The right ventricle pumps blood through the pulmonary valve into the pulmonary artery, which carries it to the lungs.

4. Lungs: In the lungs, the blood releases carbon dioxide and picks up oxygen.

5. Left Atrium: Oxygen-rich blood returns from the lungs to the left atrium through the pulmonary veins.

6. Left Ventricle: Blood passes through the mitral valve into the left ventricle.

7. Aorta: The left ventricle pumps blood through the aortic valve into the aorta, the main artery that distributes oxygenated blood to the rest of the body.

Four chambers of the heart

heart valves

Arteries

Blood vessels that pump blood away from the heart.

Veins

Blood vessels that bring blood back toward the heart.

Capillaries

The smallest vessels and the primary site for gas exchange.

Pericardial Fluid

Fluid within the pericardial cavity that reduces friction as the heart beats.

Base of the Heart

The superior portion of the heart.

Apex of the Heart

The inferior, lateral pointed tip of the heart.

Nodal Cells

Specialized cells that allow cardiac muscle to contract without nervous system input.

Intercalated Discs

Structures that allow the heart to be stimulated and contract as a single unit.

Fossa Ovalis

A depression in the right atrium; a remnant of the fetal foramen ovale.

Chordae Tendineae

"Heart strings" that anchor the valves to papillary muscles.

Coronary Sinus

The vessel where major cardiac veins drain before entering the right atrium.

Systole

The contraction phase of the cardiac cycle.

Diastole

The relaxation phase of the cardiac cycle.

Bradycardia

A slow heart rate, typically below 60 bpm.

Tachycardia

A fast heart rate, typically above 100 bpm.

SA Node

The primary pacemaker of the heart's conduction pathway.

Tunica Media

The middle layer of a blood vessel wall containing smooth muscle.

Vasa Vasorum

Small vessels that supply blood to the walls of large arteries and veins.

Fenestrated Capillaries

Capillaries with pores that allow for the diffusion of large molecules and proteins.

Venous System

Acts as a blood reservoir, holding the majority of the body's blood at any given time.

Aortic Arch Branches

The Brachiocephalic, Left Common Carotid, and Left Subclavian arteries.

Carotid Sinus

An important structure for monitoring blood pressure and chemistry.

Circle of Willis

A network of arteries providing extensive blood supply to the brain.

Hepatic Portal System

A venous network that carries nutrient-rich blood from digestive organs to the liver.

Umbilical Vein

Carries oxygenated blood from the placenta to the fetus.

Umbilical Arteries

Carry deoxygenated blood from the fetus to the placenta.

Foramen Ovale

A fetal heart opening that allows blood to bypass the lungs.

Subclavian Veins

The location where lymph fluid drains back into the venous system.

Lymphedema

Swelling caused by a blockage or problem within the lymphatic vessels.

Thoracic Duct

The main duct collecting lymph from the left side of the head, chest, and the entire lower body.

T Cells

Lymphocytes responsible for cell-mediated immunity.

B Cells

Lymphocytes that produce antibodies.

Natural Killer (NK) Cells

Lymphocytes that provide innate immune surveillance.

Lymphocytopoiesis

The production of lymphocytes.

Afferent Vessels

Lymphatic vessels that bring lymph into a lymph node.

Efferent Vessels

Lymphatic vessels that carry filtered lymph out of a lymph node.

Hilum

The region of an organ where arteries, veins, and lymphatic vessels enter or exit.

Spleen

Filters blood, removes damaged RBCs, and can initiate T and B cell responses.