This site is 100% ad supported. Please add an exception to adblock for this site.

Physiological Science 111B Module 2 Lecture 2


undefined, object
copy deck
Pulmonary Artery
Pulmonary Vein
Pulmonary Artery: only artery in the body that carries “deoxygenated” blood
Pulmonary Vein: only vein in the body that carries “oxygenated” blood
Valvular Diseases
Stenosis, Regurgitation, Prolapse
-Valvular diseases impact pressure; e.g. aortic stenosis increases pressure in the L ventricle dramatically; blood backs up into ventricle and increases in the L atrium and pressure in lung eventually increases
Stenosis/ Mitral Stenosis
A valvular disease in which leaflets of the valves are scarred together. Since the valve cannot open properly, blood cannot flow across chambers. In mitral stenosis, blood will back up in the L atrium and the lungs (pulmonary congestion and congestive heart failure can result). If a stenosis is present in the aortic valve (which can result in cardiac hypertrophy) or pulmonary valve, blood will back up in the ventricle and the pressure will build up in the ventricle.
Regurgitation (Valvular Insufficiency)
This is caused by a leaky valve that does not close properly. EX for the mitral valve: blood can go backwards into the L atrium. If occurs in aortic valve, blood will go back into L ventricle, so less will be going to the rest of the body tissues.
The chambers of the heart do not beat in proper sequence and this may be a problem with the conductive tissues of the heart. There are many different kinds of arrhythmias, and while some are lethal, all decrease the efficiency of the heart as a pump. E.g. fibrillation: the muscle cells beat in an uncoordinated fashion.
Atrial fibrillation can lead to blood clots.
Ventricular fibrillation can lead to death if not converted.
Heart Sounds:
Characteristic Rhythm
Leaky Valve Valvular Sound
Replacing Stenotic Valves
Stethoscope used to listen to proper heart function.
“Lub”: AV valves closing; “Dub”: pulmonary and aortic valves closing.
Leaky valve valvular sound: “swishing” rather than snapping shut = heart murmur
Since valves have no metabolism, nerve or blood supply, pig valves are used to replace stenotic valves. There is little chance for rejection.
What does the relative thickness of the heart muscle depend on?
1.) Preload: the amount of blood returning to the heart.
2.) Afterload: the resistance to blood flow.
Characteristics of the ATRIA
The atrial walls are thin, as there is very little resistance to flow in the atria (the atria are exposed to low forces) and its contraction is not essential to flow, as most of the flow into the ventricle is due to suction during relaxation and gravity (only ~20% of the flow is due to atrial contraction).
Characteristics of the VENTRICLES
The ventricular walls are thick, esp. the L side, as they do more work due to increased resistance to flow from higher vascular pressure (exposed to higher forces). The difference b/w the R and L side, even though the volume of blood moved is equivalent, is the increased afterload present on the L side. In addition, the systemic vascular resistance is much higher than in the lung vasculature.
Average Chamber Pressures
Venae Cavae
R/L atria
R/L ventricles
Pulmonary Artery
Venae Cavae: 2-3mmHg
R/L atria: R 5/3; L 10/5
R/L ventricles: R 20/3; L 120/5
Pulmonary Artery: 20/8
Aorta: 120/80
The 2 Phases in which the heart operates:
1.) Systole: Cardiac contraction – heart is ejecting blood – higher blood pressure (BP)
2.) Diastole: Cardiac relaxation – the period when ventricles fill with blood – lower BP
Non-contractile Nervous Tissue
The heart is made up of non-contractile nervous tissue that is responsible for the electrical activity of the heart.
Valve leaflets become inside-out. This can lead to insufficiency and/or an arrhythmia.

Deck Info