B4. Organising animals and plants Flashcards
What is the function of the trachea?
The trachea connects the nose and mouth to to the lungs/bronchi
What are the alveoli?
Alveoli are tiny air sacs surrounded by a network of capillaries, serving as the site of gas exchange between the air and the blood.
Describe the role of the bronchi.
The bronchi branch off the trachea and carry air into the right and left lungs. They contain mucus to trap dust and pathogens
Which process takes place at the alveoli?
The process that takes place in the alveoli is gas exchange
What are the features of alveoli that make them an efficient exchange surface?
They have a large total surface area
They provide a short diffusion distance
They have a good blood supply and good ventilation, maintaining a steep concentration gradient
They are lined with a layer of moisture in which gases can dissolved
How is a steep concentration gradient fir both oxygen and carbon dioxide maintained in the alveoli?
Good ventilation means that a high concentration of oxygen and a low concentration of carbon dioxide is maintained inside the alveoli
A good blood supply ensures that blood is constantly flowing; this means that the blood immediately next to each alveolus is always low in oxygen and high in carbon dioxide
How does a dense capillary network directly surrounding the alveoli help to increase the rate of gas exchange?
A dense network of capillaries directly surrounding the alveoli helps to maximise the rate of gas exchange by providing
a short diffusion distance between the alveoli and the red blood cells
A large surface area over which gas exchange can occur
Why is a faster rate of gas exchange important during exercise?
A faster rate of gas exchange is important during exercise as a greater amount of oxygen is required for a higher rate of respiration in muscle tissues. There is also a higher quantity of carbon dioxide being produced which needs excreting from the body via the lungs
What is the function of the heart?
The heart is an organ that pumps oxygenated blood from the lungs to the rest of the body and deoxygenated blood from the body to the lungs
Describe the pathway of deoxygenated blood through the heart from the body
- Enters the right atrium through the vena cava
- Flows through the atrio-ventricular valve into the right ventricle
- Is pumped through the pulmonary semilunar valve into the pulmonary artery
- To the lungs for oxygenation
Why does the left ventricle have a thicker muscle wall than the right ventricle?
The left ventricle has a thicker muscle wall to pump oxygenated blood at high pressure throughout the body, while the right ventricle pumps deoxygenated blood at lower pressure to the lungs
What role do valves play in the heart?
Valves in the heart to prevent the backflow of blood, ensuring that blood flows in only one direction through the heart chambers and vessels
How does blood return from the lungs to the heart?
Oxygenated blood returns from the lungs to the heart via the pulmonary veins
What supplies the cardiac muscle tissue of the heart with oxygenated blood?
The coronary arteries supply the cardiac muscle tissue of the heart with oxygenated blood, ensuring it receives a constant supply of oxygen and glucose for aerobic respiration to release energy for muscle contraction
How does the heart prevent damage to the capillaries in the lungs?
The heart maintains low pressure in the pulmonary artery, preventing damage to the capillaries in the lungs during blood circulation. The muscle in the right hand side of the heart is thinner and weaker to allow this
Which vein is the only vein in the body to carry oxygenated blood?
The pulmonary vein is the only vein to carry oxygenated blood, returning blood to the heart after gas exchange has taken place
What are the three main types of blood vessel?
Arteries, veins and capillaries
What is the function of arteries?
Arteries carry blood at high pressure away from the heart
How are the walls of arteries adapted to their function?
Arteries have thick muscular walls containing elastic fibres to withstand high blood pressure and maintain it as the blood recoils. They also have a narrow lumen to help maintain high blood pressure?
What is the function of veins?
Veins carry blood at low pressure towards the heart