Transport in animals- Heart Flashcards
Label a diagram and a photograph of the external structure of the heart.
Find an online labellling website
Practice drawing simplified strucutres
Label a diagram and a photograph of the internal structure of the heart.
https://www.purposegames.com/game/label-the-heart-quiz
Pracitce
Explain why the heart is called a “double pump”.
- It consists of two muscular pumps
- The right side pumps deoxygenated blood to the lungs
- Left side pumps oxygenated blood to the rest of the body
Describe the structure of the heart.
- The heart is made of cardiac muscle, which contracts and relaxes in a regular rhythm, it doesn’t get fatigued like skeletal muscle
- The coronary arteries supply the cardiac muscle with the oxygenated blood it needs to keep contracting and relaxing all the time.
- The heart is surrounded by inelastic pericardial membranes which help prevent the heart form over-distending with blood
Draw a diagram showing the flow of blood from the blood through the heart (include the names of the blood vessels adjoining the heart as well as whether the blood is oxygenated or deoxygenated and where the blood has come form or is going to).
- Deoxygenated blood enters the right atrium of the heart from the upper body and head in the superior vena cava and from lower body in the inferior vena cava
- The blood passes through the tricuspid valve into the right ventricle
- This then contracts forcing the deoxygenated blood though the semilunar valves into the pulmonary artery, which takes it to the lungs
- Then oxygenated blood form the lungs flows through the pulmonary vein into the left atrium
- The blood passes through the bicuspid valves into the left ventricle.
- The left ventricle then contracts forcing the oxygenated blood through the semilunar valves into the aorta, it then travels round the whole body.
Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.
- The lungs are relatively close to the heart, and the lungs are much smaller than the rest of the body
- The right side has to pump blood a relatively shor distance and only has to overcome the resistance of the pulmonary circulation
- The left side has to produce sufficient force to overcome the resistance of the aorta and arterial systems of the whole body and move blood under pressure to the whole body
Explain why the walls of the ventricles are thicker than the walls of the atria.
- Ventricles have to pump blood out of the heart
2. Atria only need to move blood to the ventricles
Describe the function of the valves and tendinous cords (valve cords/tendons) in the heart.
- The atrioventricular valves link the atria to the ventricles and the semi-lunar valves line the ventricles to the pulmonary artery and aorta
- The valves only open one way
- If there is a higher pressure behind a valve it is forced to open, if the force is higher in front, it is forced to shut
- Means the flow of blood is unidirectional and prevent backflow
- The tendinous cords make sure the valves are not turned inside out by the pressure exerted when the ventricle contracts
State the location and function of the septum in the heart.
- The septum is the inner dividing wall of the heart.
2. It prevents the mixing of oxygenated and de-oxygenated blood
Name the stages in the cardiac cycle and outline what is happening at each stage.
- Diastole- atria and then ventricles fill with blood
- Atrial systole- atria contract
- Ventricular systole- ventricles contract forcing blood out of heart.
Describe what happens during diastole
- The heart relaxes
- Higher pressure in the pulmonary artery and aorta closes the SL valves to prevent backflow to ventricles
- Blood moves into atria from veins, this increases the pressure of the atria
- This means the ventricle pressure falls below that of the atria so the AV valves open.
- Some blood moves passively into the ventricle
Describe what happens during atrial systole
- The ventricles are relaxed
- The atria contract decreasing the volume inside the chambers
- This pushes blood into the ventricles through the AV valves
- Causes slight increase in ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria.
Describe what happens during ventricular systole
- The atria relax
- The ventricles contract- decreasing their volume which increases their pressure
- The pressure becomes higher in the ventricles than the atria which forces the AV valves shut to prevent backflow to the atria.
- The pressure in the ventricles is also higher than in the aorta and pulmonary artery, which forces open the SL valves and blood is forced into the arteries.
Interpret a graph of aortic pressure
- Rises when ventricles contract as blood is forced into aorta.
- Then it gradually falls but never below 12kPa - because of elasticity of walls creates a recoil action- temporary pressure
Interpret a graph of atrial pressure
- Always relatively low
- Highest when contracting but drops when left AV valve closes and walls relax.
- Then there is a build up of pressure as they fill with blood.
- Until a slight drop when AV valve opens
Interpret a graph of ventricular pressure
- Low at first but gradually increases as the ventricles fill with blood as the atria contract.
- The pressure rises dramatically when the AV valve close as the ventricle contracts
- As the pressure goes above the aortic pressure blood is forced into the aorta and the semi lunar valves open
- Pressure falls as the ventricles empty and walls relax
- Semi-lunar valves shut when the pressure of the ventricle becomes lower than the aorta
Interpret a graph of ventricular volume
- Rises as the atria contract and the ventricles fill with blood.
- Drops suddenly as blood is forced out into aorta hen semi-lunar valves open
- Volume increases as ventricles fill with blood again
Define the term myogenic
Muscle which has it’s own intrinsic rhythm
Define the term sino-atrial node (SAN)
Region of the heart that initiates a wave of excitation that triggers the contraction of the heart