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Circulatory and Transport Systems
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Circulatory and Transport Systems
Circulatory and Transport Systems
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Question
What is the main difference between arteries and veins in terms of the direction of blood flow?
Answer
Arteries carry blood away from the heart, while veins carry blood towards the heart.
Question
Describe the layers that make up an artery and their functions.
Answer
An artery has three main layers: the endothelium (a slippery inner layer that reduces friction for smooth blood flow), a thick muscle layer (provides strength to withstand high pressure and is controlled involuntarily by the autonomic nervous system), and the adventitia (the thickest layer providing strength). The artery also has a narrow lumen which allows fast blood flow.
Question
Why are arteries thicker and have more elastic layers than veins?
Answer
Arteries are thicker and have more elastic layers to withstand and manage the higher pressure of blood being pumped directly from the heart. The elasticity allows them to stretch and recoil for continuous blood flow.
Question
What is the structure of capillaries and how does it relate to their function?
Answer
Capillaries are made of a single layer of endothelial cells, making them very thin and permeable. Their small lumen size and extensive branching (capillary beds) allow time and surface area for efficient nutrient and gas exchange between blood and tissues.
Question
How do veins differ structurally from arteries and why?
Answer
Veins have a thinner muscle layer and adventitia, a wider lumen, and contain valves. These features reflect lower blood pressure in veins and the need to prevent backflow and ensure unidirectional blood flow back to the heart.
Question
What role do valves play in veins?
Answer
Valves in veins prevent the backflow of blood, ensuring that blood flows in one direction towards the heart.
Question
Explain how waste blood is transported through the circulatory system and how it becomes oxygenated.
Answer
Waste blood, which is low in oxygen and high in carbon dioxide, travels from capillaries into venules and veins toward the heart. The heart pumps this blood into the pulmonary circulation (lungs) where carbon dioxide leaves, and oxygen enters the blood in pulmonary capillaries. Oxygen-rich blood then returns to the heart to be pumped throughout the body.
Question
What factors influence the measurement of pulse rate, and how can the pulse be measured?
Answer
Pulse rate is the number of heartbeats per minute. It can be measured by feeling the pulse at accessible arteries like the radial artery on the wrist or the carotid artery in the neck, then counting the number of beats in 60 seconds.
Question
What is the role of coronary arteries in the circulatory system?
Answer
Coronary arteries supply blood to the cardiac muscle itself, providing oxygen and nutrients necessary for heart function.
Question
What causes an occluded artery and what health problems can it lead to?
Answer
An occluded artery is caused by a buildup of plaque that blocks or narrows the artery, restricting blood flow to the heart, which can lead to health problems such as heart attacks.
Question
Describe the main parts of a plant root involved in transport and their functions.
Answer
The root contains the epidermis (absorbs water), cortex (stores food reserves), and endodermis. Inside the endodermis, xylem is located at the centre, responsible for transporting water up to the stem and leaves, while phloem is on the outside and transports carbohydrates.
Question
How does the structure of the plant stem relate to its function in transport?
Answer
The stem's vascular bundles (xylem and phloem) branch out toward the outside as the stem forms, facilitating transport of water, minerals, and carbohydrates between roots and leaves.
Question
How do guard cells and stomata regulate water movement in plants?
Answer
Guard cells control the size of the stomata (small openings on leaves), which influences the rate of transpiration (water loss). By opening or closing stomata, the plant regulates how much water evaporates through the leaves.
Question
Explain the formation and structure of xylem vessels.
Answer
Xylem vessels form when living cells stack up, die, and merge together. The result is a hollow tube with thick, lignin-reinforced walls that provide strength. Pits in the walls allow water to move easily in and out.
Question
What is capillary action, and how does it contribute to water movement in plants?
Answer
Capillary action is the movement of water from the roots up through the stem and to the top of the plant. Water absorption in the root creates negative pressure, and water moves upward aided by cohesion (water molecules sticking together) and adhesion (water molecules sticking to vessel walls).