Circulatory and Lymphatic Systems Lecture Notes

A collection of vocabulary flashcards covering the functions, components, and physiology of the human circulatory and lymphatic systems as discussed in the lecture notes.

Erythrocytes

Commonly known as red blood cells (RBCs), these cells transport oxygen to other cells in the body.

Leukocytes

Commonly known as white blood cells (WBCs), these cells perform immune functions that protect against various pathogens.

Cardiovascular System

A division of the circulatory system consisting of the heart and blood vessels.

Lymphatic System

A division of the circulatory system including lymphatic vessels and lymphoid tissues within the spleen, thymus, tonsils, and lymph nodes.

Arteries

Blood vessels that carry blood away from the heart and branch into progressively smaller vessels.

Arterioles

The smallest of the arteries which delivery blood to capillaries.

Capillaries

The thinnest and most numerous blood vessels across which all exchanges of fluid, nutrients, and wastes occur.

Venules

Microscopic veins that receive blood from capillaries and deliver it to larger veins.

Interstitial Fluid

Fluid derived from blood plasma that passes into surrounding tissues through capillary walls.

Lymph

Fluid located within lymphatic vessels that is eventually returned to the venous blood.

Plasma Proteins

Constituents that make up $7-9$ percent of the plasma, consisting of albumins, globulins, and fibrinogen.

Albumins

The smallest and most abundant plasma proteins ($55-60$%) which provide osmotic pressure to draw water into capillaries.

Globulins

Plasma proteins grouped into alpha, beta, and gamma subtypes; alpha and beta transport lipids, while gamma globulins are antibodies.

Fibrinogen

A clotting factor produced by the liver that is converted into insoluble threads of fibrin during clot formation.

Serum

The fluid remaining from clotted blood, which is identical to plasma but lacks fibrinogen.

Hemoglobin

A molecule in erythrocytes consisting of four protein chains called globins, each bound to an iron-containing heme group that binds oxygen.

Transferrin

A protein carrier that transports recycled heme iron or dietary iron in the blood to the bone marrow and liver.

Iron-deficiency anemia

The most common form of anemia, resulting from insufficient iron for hemoglobin production, often due to blood loss.

Pernicious anemia

Anemia usually caused by a lack of intrinsic factor, which is required for the absorption of vitamin $B_{12}$.

Aplastic anemia

Anemia produced by damage to the bone marrow, often caused by chemotherapy or radiation therapy.

Diapedesis

The process by which leukocytes squeeze through pores in capillary walls to move to a site of infection; also known as extravasation.

Neutrophils

The most abundant type of leukocyte; immature forms are called band cells, and mature forms are known as polymorphonuclear leukocytes (PMNs).

Lymphocytes

The second most numerous leukocyte type; small cells with round nuclei that provide specific immune responses.

Monocytes

The largest of the leukocytes, characterized by kidney-shaped nuclei.

Platelets

Also called thrombocytes, these are cell fragments derived from megakaryocytes in the bone marrow that function in blood clotting.

Hematopoiesis

The constant process of blood cell formation from hematopoietic stem cells.

Erythropoietin

A hormone secreted by the kidneys that stimulates the production of red blood cells.

Thrombopoietin

A hormone secreted by the liver that stimulates the maturation of megakaryocytes and the production of platelets.

ABO System

The major group of RBC antigens where individuals are classified as type A, B, AB, or O based on the presence or absence of specific antigens.

Agglutination

The clumping together of donor RBCs when a recipient's antibodies attach to them during a transfusion reaction.

Rh factor

A group of RBC antigens, the most important being antigen D ($Rho(D)$), used to determine if blood is Rh positive or Rh negative.

Hemostasis

The cessation of bleeding through physiological mechanisms such as vasoconstriction, platelet plug formation, and fibrin production.

von Willebrand’s factor (VWF)

A protein that binds to both collagen and platelets to anchor platelets to an injury site against the force of blood flow.

Platelet release reaction

The event where platelets stuck to collagen release ADP, serotonin, and thromboxane $A_{2}$ to recruit more platelets.

Intrinsic pathway

A blood clotting pathway initiated by exposure to negatively charged structures like collagen, activating factor XII without external chemicals.

Extrinsic pathway

A shorter blood clotting pathway initiated by tissue factor, which is a membrane glycoprotein found outside the blood.

Plasmin

An enzyme that digests fibrin into ‘split products,’ promoting the dissolution of a blood clot.

Myocardium

A single functioning unit formed by bundles of myocardial cells; the heart has separate atrial and ventricular myocardia.

Pulmonary circulation

The circuit that carries blood from the right ventricle through the lungs for gas exchange and back to the left atrium.

Systemic circulation

The circuit that carries oxygen-rich blood from the left ventricle to the organ systems and back to the right atrium.

Atrioventricular (AV) valves

One-way valves between the atria and ventricles; includes the tricuspid valve on the right and the mitral (bicuspid) valve on the left.

Semilunar valves

One-way valves located at the pulmonary artery and aorta that open during ventricular contraction.

Systole

The phase of the cardiac cycle characterized by contraction of the heart chambers.

Diastole

The phase of the cardiac cycle characterized by relaxation of the heart chambers.

Stroke volume

The amount of blood ejected from the ventricles during systole; roughly $2/3$ of the end-diastolic volume.

Isovolumetric contraction

The phase at the start of systole when the ventricles are contracting but all valves are closed, so volume does not change.

Sinoatrial node (SA node)

The primary pacemaker of the heart, located in the right atrium, which spontaneously generates action potentials.

Pacemaker potential

The slow spontaneous depolarization of the SA node during diastole, also called diastolic depolarization.

HCN channels

Unique ion channels in pacemaker cells that open in response to hyperpolarization and allow $Na^+$ entry (funny current).

Ectopic pacemaker

An abnormal pacemaker region, such as the AV node or Purkinje fibers, that takes over if conduction from the SA node is blocked.

Electrocardiogram (ECG/EKG)

A recording of the electrical potential differences generated by the heart and conducted to the body surface.

P wave

The ECG wave representing the spread of depolarization through the atria.

QRS wave

The ECG wave representing the spread of depolarization into the ventricles.

T wave

The ECG wave representing the repolarization of the ventricles.

Tunica externa

The outermost layer of blood vessel walls, composed of connective tissue.

Tunica media

The middle layer of blood vessel walls, primarily composed of smooth muscle.

Tunica interna

The innermost layer of blood vessel walls, consisting of endothelium, basement membrane, and internal elastic lamina.

Fenestrated capillaries

Capillaries with wide intercellular pores covered by mucoprotein, found in the kidneys, endocrine glands, and intestines.

Discontinuous capillaries

Also called sinusoids, these have very large distances between endothelial cells and are found in the bone marrow, liver, and spleen.

Skeletal muscle pump

The action of skeletal muscles contracting and squeezing veins to ensure a one-way flow of blood toward the heart.

Atherosclerosis

The most common form of arteriosclerosis, where localized plaques (atheromas) reduce blood flow and promote thrombus formation.

Low-density lipoproteins (LDLs)

Plasma proteins that carry cholesterol to the arteries and are associated with the initiation of atherosclerotic plaques.

High-density lipoproteins (HDLs)

Protective plasma proteins that carry cholesterol away from arterial walls to the liver for metabolism.

Ischemia

A condition where tissue oxygen supply is deficient due to inadequate blood flow, often caused by atherosclerosis.

Myocardial infarction (MI)

Commonly called a heart attack, this is necrosis of myocardial cells caused by prolonged ischemia and anaerobic metabolism.

Bradycardia

A cardiac rate slower than $60$ beats per minute.

Tachycardia

A cardiac rate faster than $100$ beats per minute.

Atrial fibrillation

The most common heart arrhythmia, characterized by disorganized, rapid electrical impulses in the atria.

Ventricular fibrillation

A lethal arrhythmia where uncoordinated ventricular contractions result in an impotent pumping action and total lack of blood flow.

AV node block

A condition where damage to the AV node slows or prevents the conduction of impulses from the atria to the ventricles.