Organisation: The Cardiovascular & Respiratory System (AQA GCSE Combined Science: Trilogy: Biology): Flashcards
Exam code: 8464
1/230Still learning
Know0
- FrontThe Lungs
Name the structures air passes through on its way to the gas exchange surface of the lungs.
Was this flashcard helpful?
Cards in this collection (23)
Name the structures air passes through on its way to the gas exchange surface of the lungs.
Trachea → bronchi → bronchioles → alveoli (surrounded by a capillary network).
Alveoli
Tiny air sacs in the lungs that are the site of gas exchange, surrounded by a dense network of capillaries.
State three adaptations of the alveoli for efficient gas exchange.
Large surface area for faster diffusion.
Thin walls (one cell thick) for a short diffusion distance.
Good blood supply (dense capillaries) to maintain a steep concentration gradient.
Which gases are exchanged at the alveoli, and in which direction?
Oxygen diffuses from the alveoli into the blood.
Carbon dioxide diffuses from the blood into the alveoli to be breathed out.
Gas exchange in the alveoli occurs by the process of .
Gas exchange in the alveoli occurs by the process of diffusion.
How does breathing help to maintain efficient gas exchange?
Ventilation keeps the oxygen concentration high and the carbon dioxide concentration low in the alveoli, maintaining steep concentration gradients for diffusion.
Name the four chambers of the heart.
Right atrium and right ventricle; left atrium and left ventricle.
The atria are at the top and the ventricles at the bottom.
Explain what is meant by a double circulatory system.
Blood passes through the heart twice for each full circuit of the body.
The right ventricle pumps blood to the lungs for gas exchange; the left ventricle pumps blood around the rest of the body.
Name the five blood vessels associated with the heart.
Aorta, vena cava, pulmonary artery, pulmonary vein and coronary arteries.
Describe the pathway of blood through the heart.
Deoxygenated blood enters the right atrium via the vena cava, passes to the right ventricle, then leaves through the pulmonary artery to the lungs.
Oxygenated blood returns via the pulmonary vein to the left atrium, passes to the left ventricle, then leaves through the aorta to the body.
Why is the wall of the left ventricle thicker than that of the right ventricle?
The left ventricle pumps blood at high pressure all the way around the body, so it needs a thicker, more muscular wall.
The right ventricle only pumps blood a short distance to the nearby lungs.
The coronary arteries supply the heart muscle with blood.
The coronary arteries supply the heart muscle with oxygenated blood.
What controls the natural resting heart rate?
A group of cells in the right atrium that act as a pacemaker, sending out electrical impulses that make the heart muscle contract.
What is an artificial pacemaker used for?
It is an electrical device, implanted under the skin, used to correct irregularities in the heart rate.
Name the three types of blood vessel and state the direction each carries blood.
Arteries — carry blood away from the heart.
Veins — carry blood towards the heart.
Capillaries — link arteries to veins within the tissues.
How is the structure of an artery adapted to its function?
Thick walls containing muscle and elastic fibres withstand and maintain high pressure.
The elastic fibres stretch and recoil, and the narrow lumen helps keep the pressure high.
How is the structure of a vein adapted to its function?
Thin walls and a large lumen carry low-pressure blood back to the heart.
Valves prevent the backflow of blood.
How is a capillary adapted for the exchange of substances?
Its walls are one cell thick, giving a short diffusion distance for oxygen and carbon dioxide.
The walls are also permeable, allowing substances to pass between the blood and the tissues.
2460 ml of blood flows through a vessel in 4 minutes. Calculate the rate of blood flow.
rate = volume ÷ time
rate = 2460 ÷ 4 = 615 ml/minute
What are the four components of blood, and what is the role of plasma?
Plasma, red blood cells, white blood cells and platelets.
Plasma is the liquid (mostly water) that carries the blood cells and transports dissolved substances.
How are red blood cells adapted to their function?
Their biconcave disc shape and lack of a nucleus give a large surface area for absorbing oxygen.
They are packed with haemoglobin, which binds oxygen to form oxyhaemoglobin.
State the functions of white blood cells and platelets.
White blood cells: defend the body against pathogens, by engulfing them or producing antibodies.
Platelets: cell fragments that help the blood to clot at a wound.
In a blood smear seen under a microscope, how can you tell the cell types apart?
Red blood cells are small and have no nucleus.
White blood cells are larger and have a nucleus.
Platelets are the smallest — tiny cell fragments.
Sign up to unlock flashcards
or