The Cardiovascular System Flashcards
Pulmonary Circulation
Portion of cardiovascular system that carries deoxygenated blood away from the heart, to the lungs, and returns blood back to the heart.
Systemic Circulation
Portion of the cardiovascular system that carries oxygenated blood from the heart, to the body, and returns deoxygenated blood back to the heart.
Tricuspid Valve
Right Atrium
–[valve]–>
Right Ventricle
Note: 3 leaflets
Pulmonary Valve
Right Ventricle
–[valve]–>
Pulmonary Artery
Note: 3 leaflets
Mitral (Bicuspid) Valve
Left Atrium
–[valve]–>
Left Ventricle
Note: 2 leaflets
Aortic Valve
Left Ventricle
–[valve]–>
Aorta
Note: 3 leaflets
Valves of the Heart
Tricuspid Valve–>
Pulmonary Valve–>
Mitral Valve–>
Aortic Valve
Atrioventricular Valves
Consists of 2 valves which separate the atria from the ventricles and includes the:
- Tricuspid Valve = right atrium/right ventricle
- Mitral Valve = left atrium/left ventricle
Note: Mitral valve is also known as the bicuspid valve
Semilunar Valves
Consists of 2 valves which separate the ventricles from the vasculature and includes the:
- Pulmonary Valve = right ventricle/pulmonary artery
- Aortic Valve = left ventricle/aorta
Circulation Pathway
Right Atrium-(TV)->Right Ventricle->(PV)->Pulmonary Artery->Lungs->Pulmonary Veins->Left Atrium->[MV]->Left Ventricle->[AV]->Aorta-> Arteries->Arterioles->Capillaries->Venules->Veins->Venae Cavae->Right Atrium
Electric Conduction of Heart
Sinoatrial (SA) Node–>
Atrioventricular (AV) Node–>
Bundle of His–>
Purkinje Fibers
Sinoatrial (SA) Node
Small collection of cells, located in the right atrium, capable of self-depolarization (automaticity). Depolarization cascades thru the bedmann’s bundle to left atrium and thru internodal tracts to AV Node.
Note: The SA Node is the pacemaker of the cell and initiates impulse; 60-100 signals per minute w/o neural input
Atrioventricular (AV) Node
Located at the junction of the atria and ventricles. It is here that the signal from the SA node is delayed, allowing ventricles to fill completely before contraction. The atria and ventricles contract 100 milliseconds (0.1) apart.
Bundle of His (AV Bundle)
The collection of muscle cells embedded in the interventricular septum, specialized for electrical conduction that transmits electrical impulses from the AV node to the point of apex of the fascicular branches via the bundle branches, which then lead to the Purkinje fibers.
Purkinje Fibers
Specialized conducting fibers located in the inner ventricular walls of the heart in a space called the subendocardium. Receives electrical impulses from the Bundle of His and creates synchronized contractions of the ventricles. Responsible for heart rhythm.
Two Phases of the Heartbeat
Systole and Diastole
Systole
Ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles.
Diastole
Ventricular relaxation and closure of the semilunar valves allow blood from the atria to fill the ventricles.
Cardiac Output
The total blood volume pumped by a ventricle in 1 minute. Cardiac output is the product of:
- heart rate (HR, beats per minute)
- stroke volume (SV, volume of blood pumped per beat)
Note: Human cardiac output = 5 liters per minute
Question:
Increase in heart rate and contractility is due to?
The sympathetic nervous system
Question:
Decrease in the heart rate and contractility is due to?
The parasympathetic nervous system
Vasculature
Consists of arteries, capillaries and veins.
Arteries
Thick, highly muscular structure with an elastic quality. This allows for recoil and helps to propel blood forward within the system.
Arterioles
Small muscular arteries that control blood flow into capillary beds.
Capillaries
Narrow structures that make up microcirculation. Their endothelial linings are one cell layer thick, making them permeable to both gas and solute exchange (e.g. H2O, O2, CO2, nutrients and waste).
Venule
Small blood vessel in the microcirculation that allows blood to return from the capillary bed to drain into the larger blood vessels, the veins.
Veins
Inelastic, thin-walled structures that transport blood to the heart. They obtain the ability to stretch in order to accommodate large volumes of blood but do not recoil. Veins are compressed by surrounding skeletal muscle and have valves to prevent backflow.
Question:
Transportation of deoxygenated blood back to the heart occurs in?
Veins
Question:
Transportation of oxygenated blood away from the heart occurs in?
Arteries
Exceptions: Pulmonary Artery and Umbilical Artery
Vasculature Flow
Arteries--> Arterioles--> Capillaries--> Venules--> Veins--> Superior and Inferior Venae Cavae
Question:
What is the main cell type that comprises all vasculature vessels?
Endothelial Cells
Question:
Do arteries or veins have more smooth muscle?
Arteries
Superior Vena Cava
Returns blood from portions of the body above the heart.
Inferior Vena Cava
Returns blood from portions of the body below the heart.
Portal Venous System
Occurs when a capillary bed pools into another capillary bed through veins, before returning to the heart.
3 Portal Venous Systems
Hepatic Portal System, Hypophyseal Portal System, Renal Portal System
Hepatic Portal System
The part of the venous portal system in which blood leaves capillary beds in the walls of the gastrointestinal tract and passes through the hepatic portal vein before reaching the capillary beds in the liver.
Hypophyseal Portal System
The part of the venous portal system in which blood leaves the capillary beds in the hypothalamus and travels to a capillary bed in the anterior pituitary allowing for paracrine secretion of releasing hormones.
Renal Portal System
The portion of the venous portal system in which blood leaves the glomerus and travels through the efferent arterioles before surrounding the nephron in a capillary network called the vasa recta.
Composition of Blood By Volume
55% Plasma and 45% Cells (e.g. erythrocytes, leukocytes, platelets)
Plasma
The liquid portion of blood that holds blood cells in suspension; this makes plasma the extracellular matrix of blood cells. It is the intravascular fluid part of the extracellular fluid. It is an aqueous mixture of water, nutrients, salts, respiratory gases, hormones, and blood proteins.
3 Major Cellular Components of Blood
Erythrocytes, Leukocytes, and Platelets
Formation of Blood Cells
Formed from hematopoietic stem cells located in the bone marrow.
Function(s) of Plasma Water
Solvent for carrying other substances
Function(s) of Plasma Salts
Osmotic balance, pH buffering, regulation of membrane potential
Ex. Na+, Ka+, Ca+, Mg+, Cl-, HCO3-
Function(s) of Plasma Proteins
Osmotic balance, pH buffering, clotting, defense (antibodies)
Erythrocytes (RBC)
Lack mitochondria, a nucleus, and organelles in order to make room for hemoglobin, a protein that carries oxygen. Main functions are to transport O2 and help to transport CO2.
Note: RBC’s rely entirely on glycolysis for the production of ATP, with lactic acid as the main byproduct.
Lifespan of Erythrocytes
Red blood cells can live for 120 days in the bloodstream before being recycled in the liver and spleen.
Hematocrit
Measurement of how much of a blood sample consists of RBC’s, given as a %.
Normal Hematocrit:
- Males = 41%-53%
- Females = 36%-46%
Leukocytes
Formed in the bone marrow and are a crucial part of the immune system. Two major subdivisions:
- Granular Leukocytes
- Agranulocytes
Granular Leukocytes
The class of leukocytes that includes neutrophils, eosinophils, basophils all of which play a role in nonspecific immunity.
Agranulocytes
The class of leukocytes that includes lymphocytes and monocytes both of which play a role in immunity, with lymphocytes playing a larger role in specific immunity.
Platelets (Thrombocytes)
The cell fragments released from cells in the bone marrow known as megakaryocytes. They are present in high concentrations in the blood and are required for coagulation (blood clotting).
Hematopoiesis
The production of blood cells and platelets from hematopoietic stem cells in the bone marrow. Production of blood cells is stimulated by hormones, growth factors, and cytokines.
Hormones involved in Hematopoiesis
Erythropoietin: secreted by the kidney and stimulates RBC development
Thrombopoietin: secreted by the liver and kidney and stimulates thrombocyte development
Hemoglobin (Hg or Hgb)
Fe-containing O2-containing metalloprotein in RBC’s. Carries oxygen from the lungs to body tissues where it is released and permits aerobic respiration to provide energy to power the functions of the organism in a process called metabolism.
Question:
The largest drop in blood pressure occurs in which type of vasculature?
Answer: Arterioles
Reason: Capillaries are thin-walled and unable to withstand the pressure of the arterial side of the vasculature.
