Exam Style Question Heard And Circulatory System Flashcards
(13 cards)
Define a double circulatory system.
A double circulatory system is one in which blood passes through the heart twice in one complete circuit of the body. In mammals, one circuit goes from the heart to the lungs and back (pulmonary circulation), and a second circuit goes from the heart to the rest of the body and back (systemic circulation).
Name the blood vessels that supply the heart muscle itself with blood, and explain why the heart needs its own blood supply.
The coronary arteries supply blood to the heart muscle. They branch off from the aorta and deliver oxygen and nutrients to the heart tissue. The heart is a thick, continuously active muscle that cannot get sufficient oxygen/nutrients from the blood inside its chambers, so it needs its own dedicated blood supply.
What is the wall dividing the left and right sides of the heart called?
The wall separating the two sides of the heart is called the septum.
What is the blood vessel leaving the left ventricle called?
The vessel leaving the left ventricle (carrying oxygenated blood to the body) is the aorta.
What is the valve between the left atrium and left ventricle called?
The valve between the left atrium and left ventricle is the bicuspid valve (also called the mitral valve).
Explain why the left ventricle has a thicker wall than the right ventricle.
The left ventricle pumps blood to the entire body (except the lungs), which requires a much higher pressure, so it has a very thick muscular wall to generate that force. The right ventricle only pumps blood a short distance to the lungs at lower pressure, so it doesn’t need as thick a wall.
Describe how the structure of an artery is adapted to its function.
Arteries carry blood away from the heart under high pressure, and their structure reflects this: they have thick, muscular and elastic walls to withstand the high pressure and to stretch and recoil as blood pulses through. They have a narrow lumen which also helps maintain high pressure.
Give two ways in which red blood cells are adapted to their function.
- No nucleus – this frees up space inside the red blood cell to pack in more hemoglobin, so the cell can carry more oxygen. 2. Biconcave disc shape – the flattened, indented shape gives a large surface area to volume ratio, allowing oxygen to diffuse in and out of the cell rapidly.
Describe how phagocytes and lymphocytes protect the body against disease.
Phagocytes protect by carrying out phagocytosis – they engulf pathogens (such as bacteria) and digest them using enzymes, effectively destroying the invaders. Lymphocytes protect by producing antibodies – these are specific proteins that bind to antigens on pathogens.
Explain how a blockage in a coronary artery can lead to a heart attack.
The coronary arteries supply oxygenated blood to the heart muscle. If a coronary artery becomes blocked (for example, by a blood clot forming on a fatty plaque), the blood flow to part of the heart muscle is cut off. This means that portion of heart muscle is starved of oxygen and nutrients.
List three factors that increase the risk of developing coronary heart disease.
Any three of the following risk factors: Poor diet high in saturated fats; Smoking; Lack of exercise; Chronic stress; Genetic predisposition; Older age; Male gender.
Describe and explain what happens to the heart rate during and immediately after vigorous exercise.
During exercise, heart rate increases because your muscles are working harder and need more oxygen and nutrients; the heart beats faster to pump more blood. Immediately after exercise, the heart rate remains high for a short period to clear the oxygen debt and excess CO₂.
What effect does the hormone adrenaline have on heart rate, and why is this useful?
Adrenaline causes the heart rate to increase. It makes the heart beat faster and stronger. This is useful in ‘fight or flight’ situations because a faster heart rate means more blood – carrying oxygen and glucose – is delivered to the muscles and brain.
