Written Exam 3

Front 1

1. Discuss hemoglobin relative to its chemical structure, its function, and the color changes it undergoes during loading and unloading of oxygen. Explain how a hemoglobin molecule in the blood is used in both the cardiovascular and respiratory systems. (50 points)

Back 1

Hemoglobin is made up of the protein globin bound to the pigment heme. Each molecule contains four polypeptide chains (globins) and four heme groups, each bearing an atom of iron in its center. Its function is to bind oxygen to each iron atom. When oxygen is loaded (bound to hemoglobin), the hemoglobin becomes bright red. When oxygen is unloaded from the iron, the hemoglobin becomes dark red. (p. 635)

Front 2

Trace one drop of blood from the time it enters the right atrium until it enters the left atrium, naming and describing the function of all chambers and valves it passes through. Describe, in detail, what occurs as that drop of blood moves through that circuit. Also, explain how that drop of blood changes from a deoxygenated to oxygenated state.

Back 2

The blood enters the right atrium through the superior or inferior vena cavae, depending on if the blood is coming from above the right atrium or from below. Then when the right atrium contracts, it pushes the blood through the tricuspid valve and into the right ventricle. The right ventricle contracts and pushes the blood through the pulmonary valve and into the pulmonary artery, which takes the deoxygenated blood to the lungs to get rid of the carbon dioxide and obtain oxygen. The blood returns from the lungs to the left atrium through pulmonary veins. When the left atrium contracts, it forces blood through the mitral valve and into the left ventricle. The left ventricle contracts and pushes the blood with a lot of force through the aortic valve and into the aorta which has many other arteries branching off. The blood travels through arteries because of blood pressure. The arteries get smaller and smaller and are called arterioles. The arterioles lead to capillaries, which connect arterioles and veinules (small veins). The blood drops off nutrients and oxygen to the cells and takes away wastes and carbon dioxide. It continues through the network of capillaries until it reaches the veinules. The blood continues through veinules until it reaches veins and finally the superior or inferior vena cavae. The blood moves through veins by skeletal muscle contractions, and veins have valves which prevent backwards blood flow. Then it returns to the right atrium.

Front 3

3. How is the anatomy of capillaries and capillary beds well suited to their function? Describe, in detail, gas exchange in both the pulmonary and systemic circuits. (50 points)

Back 3

Capillaries walls are very thin this allows maximal delivery of the nutrients. They have pores for exchange, and are devoid of muscle and connective tissue.

The human gas-exchange process transfers the gases contained by the human blood in exchange for the gases found in atmosphere. The human gas exchange process happens in the lungs and this process is accomplished by the mechanisms of the heart. The process of movement of the air in and out of the lungs is called ventilation.

Humans have closed circulatory system or two-circuit circulatory systems, the pulmonary circuit and the systemic circuit.

Hence, the pulmonary circulation represents the circulation of the deoxygenated blood from the right ventricle of the heart to the lungs, through pulmonary artery, for oxygenation purposes, and then, back, from lungs, through pulmonary veins, to the left atrium of the heart.

The systemic circulation transports the oxygenated blood from the heart to the body and it carries back the deoxygenated blood from the body to the heart. In the systemic circulation the arteries carry the oxygenated blood to the tissues and the veins transport the deoxygenated blood back to the heart.

The advantage of the systemic circulation is that the blood that is delivered throughout the body has the same pressure at every point.

Front 4

4. When you move on a long-term basis from sea level to the mountains, your body makes respiratory and hematopoietic adjustments via an adaptive response called acclimatization. Please describe, in detail, the effects on these adjustments in high-altitude conditions. (50 points)

Back 4

The further you move away from sea level up into higher altitudes, the lower the air pressure is. The body has two main problems with high altitude and the corresponding lower air pressure:
Air at lower pressure has less oxygen per lungful. Your body adjusts to this by making more red blood cells to carry oxygen more efficiently. However, this process takes more than a week , and in the meanwhile, you may be ill.
At lower air pressure, water evaporates faster. This can lead to dehydration.