B3.2Transport

Question 1

How are the structures of capillaries adapted to their function?

Answer 1

Capillaries have a small lumen diameter (about 5-10 µm) to facilitate the close passage of blood cells, maximizing surface area for exchange. They branch extensively to increase surface area for exchange. Their walls are one cell thick (endothelium) to minimize diffusion distance, and fenestrations (pores) in some capillaries allow for increased permeability, facilitating the exchange of materials between blood and tissues.

Question 2

Compare arteries and veins based on diameter, wall thickness, lumen size, wall layers, muscle and elastic fibers, and presence of valves.

Answer 2

Diameter: Arteries have a smaller diameter than veins.

Wall Thickness: Arteries have thicker walls.

Lumen Size: Arteries have a smaller lumen size; veins have a larger lumen to accommodate blood flow.

Number of Wall Layers: Both have three layers (tunica intima, tunica media, tunica externa), but arteries have a thicker tunica media.

Muscle and Elastic Fibers: Arteries have more smooth muscle and elastic fibers to withstand high pressure; veins have fewer.

Presence of Valves: Veins have valves to prevent backflow; arteries do not.

Question 3

Given a micrograph, how can you identify a blood vessel as an artery or vein?

Answer 3

Arteries will appear with thicker walls and a smaller lumen compared to veins. The presence of valves indicates a vein, while elastic fibers and a smooth muscle layer will be prominent in arteries.

Question 4

What is the function of arteries?

Answer 4

The function of arteries is to carry oxygenated blood away from the heart to tissues throughout the body.

Question 5

Describe the structures and functions of the three layers of the artery wall.

Answer 5

Tunica Intima: The innermost layer, smooth endothelium reduces friction for blood flow.

Tunica Media: The middle layer, composed of smooth muscle and elastic fibers, allows for regulation of blood pressure and flow.

Tunica Externa: The outer layer, made of connective tissue, provides structural support and elasticity.

Question 6

How do the wall thickness, lumen size, and muscle and elastic fibers allow arteries to withstand and maintain high blood pressures?

Answer 6

The thick walls of arteries prevent rupture under high pressure, while the narrow lumen maintains high velocity and pressure. The elastic fibers allow arteries to stretch and recoil, helping to maintain blood pressure during the cardiac cycle.

Question 7

What is the unit of measurement of pulse rate?

Answer 7

The unit of measurement for pulse rate is beats per minute (bpm).

Question 8

Outline two methods for determining heart rate.

Answer 8

Palpation: Feeling the pulse at locations such as the wrist (radial artery) or neck (carotid artery).

Electrocardiogram (ECG): Measuring electrical activity of the heart to determine heart rate.

Question 9

What is the function of veins?

Answer 9

The function of veins is to return deoxygenated blood from the body back to the heart.

Question 10

How do pocket valves, thin walls, and skeletal muscles maintain the flow of blood through a vein?

Answer 10

Pocket valves prevent backflow of blood, ensuring unidirectional flow. The thin walls reduce resistance, while surrounding skeletal muscles contract during movement, squeezing the veins and aiding venous return through a process called the muscle pump.

Question 11

What is the function of the coronary arteries?

Answer 11

The coronary arteries supply oxygen-rich blood to the heart muscle itself.

Question 12

What are the cause and consequence of a coronary occlusion?

Answer 12

A coronary occlusion is typically caused by the buildup of plaque (atherosclerosis) in the arteries, which can lead to reduced blood flow, resulting in chest pain (angina) or a heart attack.

Question 13

What correlations exist between diet, lifestyle variables, and the risk of coronary heart disease?

Answer 13

Diets high in saturated fats, trans fats, and cholesterol, along with a sedentary lifestyle, smoking, and obesity, are correlated with an increased risk of coronary heart disease.

Question 14

What factors are correlated with an increased risk of coronary occlusion and heart attack?

Answer 14

Risk factors include high blood pressure, high cholesterol levels, smoking, diabetes, obesity, and a family history of heart disease.

Question 15

Outline the function of tissues in a root.

Answer 15

Vascular Bundles: Transport water (xylem) and nutrients (phloem) from the soil to the plant.

Xylem: Conduct water and dissolved minerals upward.

Phloem: Transport sugars from photosynthesis.

Cortex: Stores food and provides support.

Epidermis: Protects the root and aids in water and nutrient absorption.

Question 16

State two ways xylem and phloem can be differentiated in cross sections of the stem.

Answer 16

Xylem vessels are typically larger and located toward the center of the stem, while phloem is smaller and located toward the outside.

Xylem appears darker due to lignification, while phloem is lighter and contains sieve plates.

Question 17

Outline the function of tissues in a stem.

Answer 17

Vascular Bundles: Transport water (xylem) and nutrients (phloem).

Xylem: Conduct water and minerals upward from roots.

Phloem: Transport sugars and organic compounds throughout the plant.

Cambium: Meristematic tissue that produces new xylem and phloem.

Cortex: Stores nutrients and provides support.

Pith: Stores food and aids in transport.
Epidermis: Protects the stem and regulates gas exchange.

Question 18

How do xylem vessels maintain rigidity even under low pressure or mechanical disturbance?

Answer 18

The lignin in xylem walls provides strength and rigidity, allowing xylem vessels to withstand internal pressure changes and external mechanical disturbances.

Question 19

How is the structure of xylem vessels adapted for the transport of water under low pressure?

Answer 19

Xylem vessels are composed of dead cells with thickened lignified walls that provide structural support, preventing collapse under low pressure.

Question 20

Is transpiration a passive process?

Answer 20

Yes, transpiration is a passive process that does not require energy; it relies on the natural properties of water and environmental conditions.

Question 21

What is transpiration pull? Describe its cause and consequence.

Answer 21

Transpiration pull is the negative pressure created by the evaporation of water from leaves, which pulls water upward from the roots through the xylem vessels, facilitating continuous water transport.

Question 22

Why does the transport of water rely on cohesion between water molecules?

Answer 22

Cohesion between water molecules creates tension in the water column within xylem vessels, allowing water to be pulled upwards during transpiration.

Question 23

How does cellulose contribute to the transport of water via capillary action?

Answer 23

The cellulose walls of xylem vessels create a cohesive environment that allows water to rise through capillary action, as water molecules adhere to the cellulose and to each other.

Question 24

What tissue is used to transport water from roots to leaves in plants?

Answer 24

Xylem tissue is responsible for the transport of water from roots to leaves.

Question 25

What is the function of the coronary arteries?

Answer 25

The coronary arteries supply oxygen-rich blood to the heart muscle itself.

Question 26

What are the cause and consequence of a coronary occlusion?

Answer 26

A coronary occlusion is typically caused by the buildup of plaque (atherosclerosis) in the arteries, which can lead to reduced blood flow, resulting in chest pain (angina) or a heart attack.

Question 27

What correlations exist between diet, lifestyle variables, and the risk of coronary heart disease?

Answer 27

Diets high in saturated fats, trans fats, and cholesterol, along with a sedentary lifestyle, smoking, and obesity, are correlated with an increased risk of coronary heart disease.