Pulmonary Circulation Flashcards
Pulmonary circulation
Right side of the heart accepts deoxygenated blood returning from the body and moves it to the lungs by way of the pulmonary arteries; constitutes the first pump.
Systemic circulation
Left side of the heart receives oxygenated blood from the left side of the lungs by way of the pulmonary veins and forces it out of the body through the aorta.
Atria
Thin-walled structures where blood is received from either the venae cavae (deoxygenated blood entering the right heart) or the pulmonary veins (oxgyenated blood entering the left heart)
Ventricles
Atria send blood to the ventricles, which contract to send blood to the lungs (right ventricle) and the systemic circulation (left ventricle).
Are atria or ventricles more powerful
Ventricles are more muscular, allowing for more powerful contractions that are necessary to push blood through the rest of the body.
Atrioventricular valves
Separates atria from ventricles
Semilunar valves
Separates ventricles from vasculature. Includes pulmonary and aortic valves, and have 3 leaflets each.
Tricuspid valve
Valve between right atrium and right ventricle
Mitral/bicuspid valve
Valve between left atrium and left ventricle
Pulmonary valve
Separates right ventricle from the pulmonary circulation
Aortic valve
Separates left ventricle from the aorta
Electrical pathway, in order of excitation, of the heart
The sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His (AV bundle) and its branches, and the Purkinje fibers
SA node
Where impulse initiation occurs in the heart : generates 60-100 signals per minute without requiring any neurological input.
Small collection of cell located in the wall of the right atrium.
As depolarization wave spreads from SA node, it causes the 2 atria to contract simultaneously.
Atrial systole
Contraction, results in an increase in atrial pressure that forces a little more blood into the ventricles.
Atrial kick
Additional volume of blood squeezed into ventricles; accounts for about 5-30 percent of cardiac output
AV node
Sits at the junction of the atria and ventricles. Signal is delayed here to allow the ventricles to fill completely before they contract.
Purkinje fibers
Distribute the electrical signal through the ventricular muscle
Intercalated discs
May contain many gap junctions directly connecting the cytoplasm of adjacent cells: allows for coordinated ventricular contraction.
Systole
Ventricular contraction and closure of the AV valves occurs and blood is pumped out of the ventricles
Diastole
Ventricles are relaxed, the semilunar valves are closed, and blood from the atria fills the ventricles.
Cardiac output
The total blood volume pumped by a ventricle in a minute. The volumes of blood passing through each side must be the same
Equation for cardiac output
Cardiac output (CO) is the product of heart rate (HR, beats/minute) and stroke volume (SV, volume of blood pumped/beat).
CO = HR x SV
Pathway of Circulation
Right atrium –> tricuspid valve –> right ventricle –> pulmonary valve –> pulmonary artery –> lungs –> pulmonary veins –> left atrium –> mitral valve –> left ventricle –> aortic valve –> aorta –> arteries –> arterioles –> capillaries –> venules –> veins –> venae cavae –> right atrium
How many portal systems are there in the heart and what do they do
There are 3; blood will pass through 2 capillary beds in series before returning to the heart
Hepatic portal system
Blood leaving capillary beds in the walls of the gut passes through the hepatic portal vein before reaching the capillary beds in the liver
Hypophyseal portal system
Blood leaving capillary beds in the hypothalamus travels to a capillary bed in the anterior pituitary to allow for paracrine secretion of releasing hormones
Renal portal system
Blood leaving the glomerulus travels through an efferent arteriole before surrounding the nephron in a capillary network called the vasa recta.
Plasma
The liquid portion of blood, an aqueous mixture of nutrients, salts, respiratory gases, hormones, and blood proteins.