Cardiovascular Physiology Part II

Flashcards covering cardiovascular physiology, blood components, hemostasis, blood vessel dynamics, and blood pressure regulation mechanisms based on the lecture transcript.

Blood

A specialized connective tissue that contains cells suspended in a fluid matrix, responsible for transporting gases, nutrients, and hormones while regulating pH and defending against pathogens.

Physical Characteristics of Blood

The temperature is approximately $38^\circ\text{C}$, it has high viscosity, a slightly alkaline pH of $7.35–7.45$, and a volume comprising $7\%$ of body weight.

Plasma

The watery fluid component of blood that makes up about $55\%$ of blood volume; it is more than $90\%$ water and contains dissolved proteins and solutes.

Albumin

The most abundant plasma protein ($60\%$) that is a major contributor to plasma osmolarity and transports fatty acids and various hormones.

Globulins

A category of plasma proteins ($35\%$) that includes antibodies (immunoglobulins) and transport proteins like lipoproteins and steroid-binding proteins.

Fibrinogen

A soluble plasma protein ($4\%$ of total) that functions in blood clotting by being converted into insoluble fibrin.

Erythrocytes

Also known as red blood cells (RBCs), these comprise $99.9\%$ of formed elements and are specialized biconcave discs that transport oxygen and carbon dioxide.

Hemoglobin (Hb)

A red pigment protein in RBCs consisting of four globular subunits, each containing a heme unit with an iron ion for binding oxygen.

Hematocrit

The percentage of formed elements in whole blood; normal values are approximately $46\%$ for adult males and $42\%$ for adult females.

Rouleaux

Stacks of red blood cells formed as they travel through narrow blood vessels to ensure smooth flow.

Erythropoiesis

The process of red blood cell formation, which in adults occurs in the myeloid tissue (red bone marrow).

Erythropoietin (EPO)

A hormone secreted by the kidneys during hypoxia (low oxygen levels) that stimulates the production of red blood cells.

Bilirubin

An orange-yellow pigment produced during the breakdown of heme units from recycled RBCs, which is excreted by the liver in bile.

Transferrin

A plasma protein that binds to iron and transports it through the bloodstream to the red bone marrow for the synthesis of new hemoglobin.

Agglutinogens

Surface antigens on red blood cells (such as A and B) that determine an individual's blood type.

Agglutination

The process of clumping that occurs when antibodies (agglutinins) attack foreign surface antigens on red blood cells.

Rh Factor

A surface antigen on RBCs; individuals are Rh positive if it is present and Rh negative if it is absent.

RhoGAM

A medication given to Rh-negative mothers during weeks $26–28$ of pregnancy and after delivery to prevent the development of anti-Rh antibodies.

Leukocytes

White blood cells (WBCs) that have nuclei and organelles but lack hemoglobin; they defend the body against pathogens and remove toxins and waste.

Positive Chemotaxis

The characteristic of circulating white blood cells where they are attracted to specific chemical stimuli at an injury site.

Neutrophils

The most common WBCs ($50–70\%$), which are highly active phagocytes that are the first to arrive at a bacterial infection.

Eosinophils

WBCs ($2–4\%$) that attack large parasites by releasing toxic compounds like nitric oxide and increase in number during allergic reactions.

Basophils

WBCs (less than $1\%$) that accumulate in damaged tissues and release histamine (to dilate vessels) and heparin (to prevent clotting).

Monocytes

Large, spherical WBCs ($2–8\%$) that stay in the blood for 24 hours before entering tissues to become aggressive macrophages.

Lymphocytes

WBCs ($20–40\%$) involved in specific immunity, including T cells (cell-mediated), B cells (humoral), and Natural Killer (NK) cells.

Platelets (Thrombocytes)

Disc-shaped cell fragments involved in hemostasis, circulating for $9–12$ days with concentrations of $150,000$ to $500,000$ per microliter.

Megakaryocytes

Giant cells in red bone marrow that produce platelets by shedding membrane-enclosed packets of cytoplasm.

Hemostasis

The process of stopping blood loss from a broken vessel, consisting of the vascular phase, platelet phase, and coagulation phase.

Fibrin

An insoluble protein formed from fibrinogen during the coagulation phase that creates a meshwork to trap RBCs and form a blood clot.

Thrombin

An enzyme that converts soluble fibrinogen into insoluble fibrin threads during the common pathway of coagulation.

Mean Arterial Pressure (MAP)

The average pressure driving blood forward during the cardiac cycle, calculated as Diastolic pressure + one-third pulse pressure.

Total Peripheral Resistance (TPR)

The hindrance to blood flow caused by friction from vessel walls, viscosity, and turbulence, influenced by vascular length and diameter.

Baroreceptor Reflexes

Stretch receptors in the carotid and aortic sinuses that monitor changes in blood pressure and signal the cardiovascular center to adjust cardiac output.

Chemoreceptor Reflexes

Receptors in the carotid and aortic bodies that monitor blood pH, $O_2$, and $CO_2$ levels to coordinate cardiovascular and respiratory activities.

Angiotensin II

A hormone released in response to decreased renal blood pressure that stimulates thirst, ADH secretion, and peripheral vasoconstriction.

Natriuretic Peptides (ANP and BNP)

Hormones produced by the heart in response to excessive stretching that act to reduce blood volume and blood pressure.