True or False?
Capillaries connect the smallest branches of arteries and veins.
Enjoying Flashcards?
Tell us what you think
True or False?
Capillaries connect the smallest branches of arteries and veins.
True.
Capillaries connect the smallest branches of arteries and veins.
What is the function of fenestrations in capillaries?
Fenestrations are gaps in the thin endothelial cells of some capillaries. They allow blood plasma to leak out and form tissue fluid, enabling exchange of substances like oxygen, glucose, and carbon dioxide.
What is the significance of capillary beds?
Capillary beds are networks of capillaries formed between cells. They increase the surface area for diffusion of substances to and from cells, reducing the diffusion distance.
Describe the direction of the flow of blood in arteries and veins.
Arteries carry blood away from the heart.
Veins carry blood into the heart.
Define endothelium.
The endothelium is the innermost layer of artery and vein walls, consisting of squamous epithelial cells. It is one cell thick and reduces friction for smooth blood flow.
True or False?
The elastic layer of arteries controls vasoconstriction and vasodilation.
False.
The muscle layer of arteries controls vasoconstriction and vasodilation.
How does vasoconstriction affect blood pressure?
Vasoconstriction (narrowing of the lumen) increases blood pressure by reducing the diameter of arteries.
What is the role of elastic tissue in arteries?
Elastic tissue helps maintain blood pressure by stretching and recoiling during heartbeats, evening out pressure fluctuations.
What is the purpose of valves in veins?
Vein valves prevent backflow of blood under low pressure, aiding blood return to the heart.
How do skeletal muscles assist blood movement in veins?
Skeletal muscle contractions push blood through veins, and valves prevent backward flow.
What is the main difference in wall thickness between arteries and veins?
The arterial walls are much thicker than those of veins.
Define the term 'lumen' in the context of blood vessels.
Lumen is the internal space or cavity within a blood vessel through which blood flows.
True or False?
The lumen of arteries is wider compared to the thickness of the wall.
False.
The lumen of arteries is relatively narrow compared to the thickness of the wall.
What is the purpose of the larger lumen in veins?
The larger lumen in veins helps to ensure that blood returns to the heart at an adequate speed by reducing friction between the blood and the endothelial layer.
State the relationship between lumen size and blood flow rate in veins.
In veins, the rate of blood flow is slower, but the larger lumen means the volume of blood delivered per unit of time is equal to that of arteries.
What causes a pulse in arteries?
A pulse in arteries is caused by the expansion of arteries to accommodate the large volume of blood forced through them by the contraction of the ventricles.
Where is the carotid artery located?
Carotid artery is an artery that runs down the side of the neck, where a pulse can be felt just below the jaw.
True or False?
When taking a pulse, you should use your thumb to feel for the pulse.
False.
You should not use your thumb when taking a pulse, as it also has a pulse that can lead to inaccurate results.
What is the correct method for counting pulse rate manually?
To count pulse rate manually, place two fingers on the radial or carotid artery, gently compress the blood vessel, and count the number of pulses felt for 60 seconds.
State two examples of digital devices that can be used to measure pulse rate.
Two examples of digital devices that can be used to measure pulse rate are data loggers and smartwatches / fitness bands.
Define 'occlusion of the arteries'.
Occlusion of the arteries is the narrowing of the arteries due to a blockage.
What is atherosclerosis?
Atherosclerosis is a process where fatty deposits build up under the endothelium of arteries, narrowing the lumen and reducing blood flow.
True or False?
Fibrous tissue produced to repair artery wall damage increases the overall elasticity of the artery wall.
False.
Fibrous tissue produced to repair artery wall damage is not elastic, so it reduces the overall elasticity of the artery wall.
What is a thrombus?
A thrombus is a blood clot formed within a blood vessel.
Define embolus.
Embolus is a blood clot that circulates in the bloodstream.
What is a myocardial infarction?
A myocardial infarction, or heart attack, occurs when parts of the heart muscle die due to blocked coronary arteries.
True or False?
Epidemiological studies on human populations provide a definite causal link between coronary heart disease and risk factors.
False.
Epidemiological studies provide correlation data and do not provide a definite causal link between coronary heart disease and risk factors.
What does a larger sample size in a study typically indicate?
A larger sample size is more likely to be representative as it covers a larger cross-section of the population.
Define 'validity' in the context of scientific studies.
Validity in scientific studies means that the results measure what they set out to measure, are not influenced by external variables or poor experimental design, and have been analysed correctly.
What does a correlation coefficient indicate? (NOS)
The correlation coefficient (r) indicates the strength of the relationship between variables.
What does a correlation coefficient of 1 or -1 indicate? (NOS)
A correlation coefficient of 1 or -1 indicates a perfect correlation, where all data points lie on a straight line.
True or False?
A perfect correlation coefficient proves a causal link. (NOS)
False.
A perfect correlation coefficient does not prove a causal link.
What is transpirational pull?
Transpirational pull is the pulling force created by the tension in the xylem when water moves into leaf cells, transmitted through the plant via cohesion between water molecules.
Define 'capillary action' in the context of plant water movement.
Capillary action is the movement of water that occurs due to adhesion to the walls of a narrow tube, such as the cell walls in plant xylem.
What is the cohesion-tension theory of transpiration?
The cohesion-tension theory of transpiration explains how water moves upwards through plants against gravity, due to the tension created by water loss in leaves and the cohesion between water molecules.
True or False?
The transpiration stream moves water downwards through the plant.
False.
The transpiration stream is a continuous upwards flow of water in the xylem vessels of plants.
State three ways in which transpiration is important to plants.
Transpiration is important to plants in three ways:
it provides cooling through evaporation
helps in the uptake of mineral ions
provides support to leaves and non-woody stems through turgor pressure
What are the two main functions of xylem vessels in plants?
The two main functions of xylem vessels are the transport of water and the transport of mineral ions from the roots.
What is lignin in the context of xylem vessels?
Lignin is a polymer that strengthens the walls of xylem vessels, making them extremely tough and able to withstand very low internal pressures without collapsing.
True or False?
Mature xylem vessels contain living cells.
False.
Mature xylem vessels are non-living cells, with their cell contents broken down to form long, continuous, hollow tubes.
What are pits in xylem vessel walls?
Pits are tiny pores in xylem vessel walls that allow water to enter and move sideways between vessels, ensuring continued water flow if a vessel is damaged.
State two structural adaptations of xylem vessels that facilitate water transport.
Two structural adaptations of xylem vessels that facilitate water transport are:
They are long, continuous, hollow tubes without cell content or end walls, allowing unimpeded flow
Their walls are thickened with cellulose and strengthened with lignin, enabling them to withstand very low internal pressures