Lecture 4: Heart Valves

The function of the semilunar (SL) valves: (A) As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open/closed. (B) As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them open/closed.

(A) As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open. (B) (B) As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them closed.

Two conditions severely weaken the heart. What are these two conditions? Why do they weaken the heart?

1) Incompetent valve 2) Valvular Stenosis; The heart is working hard for nothing, basically; The heart won't oxygenate blood property or distribute oxygenated blood throughout the body.

1. Blood returning to the heart fills the Atria, putting pressure against atrioventricular valves; atrioventricular valves are forced open. 2. As ventricles fill, atrioventricular valve flaps hang limply into ventricles 3. Atria contract, forcing additional blood into ventricles 4. AV valves open; atrial pressure greater than ventricular pressure. 5. Ventricles contract, forcing blood against atrioventricular valve cusps 6. The Atrioventricular valves close 7. Papillary muscles contract and chordae Tendineae tighten, preventing valve flaps from everting into atria. 8. AV valves closed; atrial pressure less than ventricular pressure. Know how Valves open and close according to pressure.

1. Blood returning to the heart fills the Atria, putting pressure against atrioventricular valves; atrioventricular valves are forced open. 2. As ventricles fill, atrioventricular valve flaps hang limply into ventricles 3. Atria contract, forcing additional blood into ventricles 4. AV valves open; atrial pressure greater than ventricular pressure. 5. Ventricles contract, forcing blood against atrioventricular valve cusps 6. The Atrioventricular valves close 7. Papillary muscles contract and chordae Tendineae tighten, preventing valve flaps from everting into atria. 8. AV valves closed; atrial pressure less than ventricular pressure.

AV valves open/close when the ventricles contract; When the ventricles contract, blood is sent upward into the pulmonary trunk (from the right ventricle) and to the aorta (from the left ventricle)

AV valves close when the ventricles contrant

Anchors the cusps (the flaps of the heart valves) to papillary muscles; it holds valve flaps in closed position.

Chordae Tendineae

Imcompetent Valve vs. Valvular Stenosis?

Incompetent Valve = heart valves don't close properly so blood backflows. Valvular Stenosis = heart valves become stiff and they don't open all the way up properly; they get too narrow.

Why are the papillary muscles called so?

Papillae = nipple like

Heart valves open and close in response to what?

Pressure changes

The atria contract together, pause, then ventricles contract together is the sound we hear of our heart beating. Why is there a pause?

So that the atria and venticles don't contract at the exact same time

Which heart valves prevent backflow into atria when ventricles contract?

The Tricuspid valve and the Mitral/Bicuspid valve.

What do the semilunar valves do? How many are there? They open and close in response to what?

The two semilunar valves (The Pulmonary Semilunar Valve and The Aortic Semilunar Valve) prevent backflow into ventricles when ventricles relax; They open and close in response to pressure changes.

What are heart valves? function?

They ensure unidirectional blood flow through the heart; they ensure that blood flows only one way and not backwards

What is Valvular stenosis? What usually causes this?

This is when you have stiff flaps and they don't open all the way up; stenosis = narrowing; So your heart must exert more force to pump the blood through the valves into the next compartment.... This is usually caused by an infection of the heart (endocarditis)

Differentiate between the Tricuspid valve and the Mitral/Bicuspid valve.

Tricuspid (has three flaps) and is on the right side of the heart. Mitral/Bicuspid: (has two flaps) and is on the left side of the heart.

True or False. Cardiac tissue can become too dense or too fibrous after infections.

True

True or False. The right and left ventricles contract together. And the right and left atria contract together.

True

What Is Incompetent valve?

Valves aren't working; they don't close properly, so your blood backflows so the heart re-pumps the same blood over and over.

What is Chordae Tendineae?

the strings of connective tissue that are attached to the heart valve flaps of the Tricuspid and Mitral valves; it pulls on them.

How are Incompetent Valve and Valvular Stenosis treated?

with Valve replacements that could be mechanical, from animals, or from cadavers.