3.1.2e Heart Flashcards
see cgp pg82 for diagram of the external structure of the heart
see cgp pg82 for diagram of the internal structure of the heart
Right side of the heart
Deoxygenated blood from the body flows into the right side of the heart which pumps it to the lungs
Left side of the heart
Oxygenated blood from the lungs returns to the left side of the heart which pumps it to the body
What is the point of valves
Valves in the heart prevent blood flowing the wrong way
The atrioventricular valves link the atria to the ventricles, & the semi-lunar valves link the ventricles to the pulmonary artery & aorta - they all stop blood flowing the wrong way
How do valves work (steps)
- The valves only open one way - whether they’re open or closed depends on the relative pressure of the heart chambers
- If theres higher pressure behind a valve, its forced open
- If pressure is higher in front of the valve, its forced shut
Equipment needed for heart dissection
- Pig/cow/sheep heart
- Dissecting tray
- Scalpel
- Apron
- Lab gloves
Method of a heart dissection
EXTERNAL EXAMINATION: Look at the outside of the heart & try to identify the 4 main vessels attached to it. Feel inside the vessels to help you - remember arteries are thick & rubbery, whereas veins are much thinner.
Identify the right/left atria, the right/left ventricles & the coronary arteries. Draw a sketch of the outside of the heart w labels
INTERNAL EXAMINATION: Cut through the walls of the left atrium, follow the cut down to the apex of the left ventricle. (look for tendinous cords, left atrioventricular valve/bicuspid valve, semi-lunar valve).
Make a similar cut down the right side of the heart to open up the right atrium & ventricle. (look for right atrioventricular valve/tricuspid valve). Measure & record the **thickness ** of the ventricle walls & note any differences between them.
Cut open the atria & look inside them too. Note whether the atria walls are thicker or thinner than the ventricle walls
Draw a sketch to show the valves & the inside of the ventricles & atria
How does blood leave the kidney & eventually return to the heart
via the renal vein
Order of vessels, organs & chambers of the heart from vena cava to aorta
Vena cava -> right atrium -> tricuspid valve -> right ventricle -> pulmonary valve -> pulmonary artery -> lungs -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic valve -> aorta
Difference in thickness between wall of the right ventricle & wall of the right atrium
Wall of the right ventricle is thicker than the wall of the right atrium
Difference in thickness between wall of the left ventricle & wall of the right ventricle
Wall of the left ventricle is thicker than the wall of the right ventricle
Why is the right ventricle wall thicker than the right atrium wall
The right ventricle has a thicker wall than the right atrium bc it needs to generate more pressure to pump blood to the lungs.
The right atrium only receives blood & pushes it into the ventricle w less effort, requiring a thinner wall.
Why is the left ventricle wall thicker than the right ventricle wall
The left ventricle has a thicker wall than the right ventricle bc it pumps blood to the whole body, requiring more pressure.
Whereas the right ventricle only pumps blood to the lungs, which requires less pressure
What is the function of the atrioventricular valves
The atrioventricular valves (bicuspid valves on the left, tricuspid valve on the right), prevent the backflow of blood from the ventricles into the atria during ventricular contraction (systole phase).
They help maintain unidirectional blood flow
Describe the role of the coronary arteries
The coronary arteries supply oxygenated blood to the heart, providing it w the oxygen & nutrients needed for proper function
Possible consequences of a blockage in a coronary artery
A blockage in a coronary artery due to fatty build up leads to reduced blood supply to the heart.
This could result in heart attacks (if there is prolonged lack of oxygen to the heart) or strokes (due to the formation of blood clots)
Why do ventricles have thicker walls than the atria
Because ventricles have to push blood out of the heart
