Question

1. A. List the components of the respiratory tract.

B. Describe the response by the respiratory system, specifically alterations of the respiratory rate, to increased pH and decreased pH and how the levels of carbon dioxide and oxygen vary with changes in pH.

C. Using partial pressures, describe the movement of oxygen and carbon dioxide in the lungs and the tissues.

D. Discuss the effects of pH and temperature changes on the oxygen dissociation curve for hemoglobin.

2. A. Discuss fluid exchange across the walls of capillaries and the formation of lymph.

B. List the three different types of capillaries and one place in the body where each could be found.

C. Describe the baroreceptor reflex.

Answer 1

1. components of respiratory tract include- nose, mouth,pharynx, larynx, trachea, bronchi, bronchioles, alveoli (lungs).

2. If ph increases, respiratory rate decreases( alkalosis) . If ph decreases, respiratory rate increases. ( acidosis)

The lungs eliminate excess co2 by increasing respiration, causing a decrease in H+ and an increase in ph.

The lungs can retain more co2 by decreasing respiration, causing an increase in H+ and a decrease in ph.

3. Pulmonary gas exchange- The partial pressure of oxygen in the alveoli is about 104 mm Hg, whereas its partial pressure in the blood of the capillary is about 40 mm Hg. This large difference in partial pressure creates a very strong pressure gradient that causes oxygen to rapidly cross the respiratory membrane from the alveoli into the blood.

Systemic gas exchange- the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue.

4. lowering of ph and increase in temperature cause the oxygen affinity of Hb to decrease and shifts curve to the right. (bohr effect). Elevated ph levels and low temperature increases the affinity of Hb for O2 and shifts the oxygen dissociation curve to the left.

5. oxygen and nutrients such as glucose diffuse out of a capillary into the interstitial fluid that surrounds cells. Wastes such as Co2 diffuse into the capillary . The relative constancy of interstitial fluid is absolutely dependent upon capillary exchange. Lymph is formed when the interstitial fluid is collected through tiny lymph capillaries which are located throughout the body. It is then transported through lymph vessels to lymph nodes, which clean and filter it.

6.

There are three types of capillary:

• continuous
• fenestrated
• discontinuous

Continuous capillaries - endothelial cells

fenestrated capillaries- small intestine, endocrine glands, kidney

discontinuous capillaries- hepatocyte cells

7. The baroreceptor reflex play a very important role in maintaining blood pressure levels specially during stress conditions. They control the autonomic activity of heart and adjust cardiac output to match upto arterial blood pressure.