This is for all A-Level students. You can use this blog to prepare for the re-take in January or secure your understanding of the unit you are currently doing.
I will post questions every two days.
Research your answer and place them directly into the blog.
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Here are the second set of questions. You have until Friday to complete......
The Circulatory system
a) Describe the flow of blood through the heart, identifying the major structures, including blood vessels, and their related functions. (8 marks)
b) How is the Frank Starling's 'Law of the Heart Mechanism' involved in increasing stroke volume during exercise?
(3 marks)
c) Define what is meant by the cardiac impulse. (2 marks)
d) Explain how the heart valves help control the direction of blood flow. (8 marks)
e) Explain why heart rate takes some time to return to its resting value following the exercise period. (3 marks)
f) What effect does enhanced venous return have upon cardiac output and stroke volume? (4 marks)
a) Blood enters the right atrium of the heart through the vena cava, emptying de-oxygenated blood from the body. The blood then flows from your right atrium into your right ventricle through the open tricuspid valve. It keeps flowing through untill the right ventricle is full. When it becomes full the tricuspid valve closes stopping blood flowing back into the right atrium during ventricular contraction. During the contraction the blood is squeased out of the pulmonic valve into the pulmonary artery transporting the blood towards the lungs.
After re oxidation of the blood in the lungs the blood is transported back to the heart through the pulminary vein. This time the blood enters into the left atrium. Again it flows down from the atrium to the ventricle but this time through the mitral valve on the left side of the heart. The valve then closes and contraction pushes blood out of the aortic valve through the aorta to all other organs of the body.
Todd (forgotten my login)
c) Movement of the chest wall caused by cardiac contraction.
Todd
d) Heart valves are there to control the flow of blood in the heart. The way they are structured means that they allow blood to pass from the atria into the ventricles. When the ventricles become full the valves automaticaly close stopping any back flow of blood back into the atria. It also means that when the heart contracts blood is forced out of the pulminary artery and the aorta. Both the tricuspid and mitral valves are one way and only allow blood to flow from the atria to the ventricles but not the other way around.
Todd
e) Heart rate rises imediately during exercise but does not return to its normal level as soon as you stop. This is because of EPOC (excess post-exercise oxygen consumption). During exercise an oxygen debt is created and when the body stops working the heart still has to keep pumping oxygenated blood around the body to get it to all the muscles and organs that need it. This aids repair and flushes out waste products from the body.
Todd
A,the blood travels to the aorta in which this carries oxygenated blood to the body. it then travels throught the bloood vessels, this is where several blood vessels are attached to the heart, they bring either oxygenated or deoxgenated blood to the heart and take it away.
the heart is divided into to 2 parts by the septum, each part contains an atrium and a ventricle. the atria are small and dont require much force. the ventricles are much thicker and contract with fgreater force to pump blood out of the body(work under high pressure). the left ventricle is larger as it pumps more blood , whereas right ventricle pumps deoxygenated blood around the body. then the blood goes through the valves which are the tricuspid valve which is located between the right atrium and ventricle, and the bicuspid vavle which is found between the left atrium and left ventricle. the the blood finally goes through the vena cava in which this carries deoxygenated blood from the body to the right atrium.
B,The Frank-Starling law of the heart states that the more the ventricle is filled with blood during diastole, the greater the volume of ejected blood will be during the resulting systolic contraction (stroke volume).
This means that the force of contractions will increase as the heart is filled with more blood. so the amount of blood pumped around the body will increase.
d, the heart valves help control the direction of blood, by regulating blood flow by ensuring it moves in only one direction. they open to allow blood to pass through and then close to prevent backflow.
E,the heart takes some time to return to its resting value after exercise because the blood was working under high pressure whilst exercising which means pumping more blood around the body to the muscles and when finished exercising the heart rate takes time to return to rest because it needs to generate all the oxygen back to the muscles and pupm blood back to a normal rate. thats why a cool down is done after exercise so that the blood is pumped round the body to all the muscles to prevent any injury.
F, venous return is the return of blood to the right side of the heart via the veins. the heart can only pump out as much blood as it receives, so cardiac output is dependant on venous return. a rapid increase in venous return enables a significant increase in stroke volume and therfore cardiac output.
Salih
f) Venous return is the flow of blood back into the heart. Therefore an enhanced venous return means more blood back into the heart and therefore an enhanced stroke volume and cardiac output. Blood pumped around the body loop. Becuase of this when one part is speeded up so is the rest and this is what causes venous return to equal caridiac output. Also if more blood is pumped into the heart then more has to be pumped back out.
Todd
A)Deoxygenated blood flows from the vena cava into the right atrium. The tricuspid valve opens and the blood enters the right ventricle. The tricuspid valve closes stopping the back flow of blood into the left atrium. The bottom of the heart contracts pumping the blood out of the left ventricle, through the pulmonic valve into the pulmonary artery transporting the blood to the lungs; where the blood becomes oxidised. Oxygenated blood flows from the pulmonary vein into the right atrium. The mitral valve opens allowing blood to flow into the right ventricle. The mitral valve then closes to stop the backflow of blood into the right atrium. The bottom of the heart contracts pumping the oxygenated blood out of the right ventricle, through the aortic valve and into the aorta where it is transported around the body; before it returns back to the heart to repeat the process.
B)The frank-Starling law of the heart states that the more the ventricle is filled with blood during diastole, the greater the volume of ejected blood will be during the resulting systolic contraction (stroke volume). Therefore the force of contractions will increase as the heart is filled with more blood and the amount of blood pumped around the body will increase.
C)A cardiac impulse is movement caused by the chest wall by a cardiac contraction.
D)Valves stop the backflow of blood, they are found in the heart and veins. Therefore blood will only be pumped in one direction.
E)The heart takes time to return to its resting value after exercise. This is due to the blood working under high pressure whilst exercising; this means that more blood is pumped around the body to the muscles. When finished exercising the heart rate takes time to return to rest, because it needs to generate all the oxygen back to the muscles (repay oxygen debt). And pump blood back around the body at a normal rate.
F) The Venous return (VR) can be defined as the return of blood to the right side of the heart via the veins. The heart can only pump out as much blood as it receives, so cardiac output is dependant on venous return. A rapid increase in venous return enables a significant increase in stroke volume and therefore cardiac output.
---Kimberley---
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