Part 4 Content


a. The veins of the systemic blood circulatory system bring oxygen-poor blood from all parts of the body to the right atrium of the heart. From the right atrium, the blood flows into the right ventricle of the heart. Upon contraction of the right ventricle, blood is forced into the pulmonary arch. The pulmonary arch divides into the right and left pulmonary arteries that delivers the oxygen-poor blood to their respective lungs. Paralleling the branching of the respiratory tree, the arteries divide and subdivide within the lungs. These arteries lead to capillaries that surround the alveoli. The walls of these capillaries are thin enough to accommodate the passage of gases to and from the alveolus. The oxygen-poor blood gives up the carbon dioxide which it has been carrying and absorbs oxygen from the alveolus. Just as oxygen travels from the alveolus to the capillary, carbon dioxide travels from the capillary to the alveolus. b. The blood, now saturated with oxygen, is collected by the pulmonary venous system. The blood flows through the pulmonary veins into the left atrium of the heart. From the left atrium, it flows into the left ventricle. When the left ventricle contracts, the oxygen-rich blood is forced into the aorta of the systemic blood circulatory system. Other arteries branch off of this large artery and carry the oxygen-rich blood to all living cells within the body. As the arteries continue to subdivide and get smaller, they eventually reach the capillary stage. At this stage, oxygen moves from the blood into the surrounding body cells and carbon dioxide, a waste material, travels from the body cells to the blood. The blood then flows from the capillaries into veins and eventually returns to the right atrium of the heart.

1-11. TRANSPORTATION OF GASES Oxygen and carbon dioxide are the primary gases involved in respiration. Under special circumstances, nitrogen may also be of concern. Some of the gases are dissolved directly in the plasma of the blood. Most of the gasses, however, are carried within the erythrocytes (red blood cells, commonly called RBCs). The RBCs, found in great numbers in the blood, are specially constructed for transporting the gases. Hemoglobin, a substance found within RBCs, has a great affinity for oxygen. Yet, the hemoglobin can readily give up the oxygen wherever it is needed. 

Exercises for Lesson 1

1. Name and define the two types of respiration. a. ______________________________________________________________ ______________________________________________________________ b. ______________________________________________________________ ______________________________________________________________

2. What does the larynx control? ______________________________________________________________

3. What is found in the nose to filter inflowing air? ______________________________________________________________

4. The walls of the nasal chambers are lined with a thick mucous-type membrane called the ________________________________________________________.

5. The common posterior space for the respiratory and digestive systems is called the ______________________________________________________________.

6. The part of the pharynx that is related to the respiratory system is the: ______________________________________________________________.  1-12

7. The tubes that are used to equalize the pressure between the outside and inside of the eardrum are called ____________________________________________.

8. How is the upper respiratory passageway closed when the person swallows food? ______________________________________________________________ ______________________________________________________________

9. Which flap prevents food from entering the larynx during swallowing? ______________________________________________________________

10. The two common terms that refer to the larynx are _______________________ and _______________________________________.

11. Describe the alveoli. ______________________________________________________________ ______________________________________________________________

12. Which lung is the smaller lung and why? ______________________________________________________________ ______________________________________________________________

13. Where is the mediastinum located? ______________________________________________________________ ______________________________________________________________  1-13

14. How is Boyle's law related to a person's breathing? ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________

15. During inhalation, how is the rib cage lifted? ______________________________________________________________ ______________________________________________________________

16. Describe the action of the diaphragm during inhalation. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________

17. Which part of the brain controls the respiratory reflexes? ______________________________________________________________ ______________________________________________________________

18. The primary gases involved in respiration are ______________________ and ________________________.

Check Your Answers on Next Page 


1. External respiration is the exchange of gases between the air in the lungs and blood. Internal respiration is the exchange of gases between the blood and the individual cells of the body. (para 1-1b)

2. The larynx controls the volume of inflowing air and produces selected pitch (vibration frequency) in the moving column of air. (para 1-2b(2))

3. Hairs in the nose filter inflowing air. (para 1-3a)

4. Mucoperiosteum. (para 1-3b(1))

5. Pharynx. (para 1-3c)

6. Nasopharynx. (para 1-3c(1))

7. Auditory (eustachian) tubes. (para 1-3c(1))

8. The soft palate floor of the nasopharynx is a trapdoor that closes off the upper respiratory passageways during swallowing. (para 1-3c(1))

9. The epiglottis. (para 1-3c(2))

10. Adam's apple and voice box. (para 1-4)

11. The alveoli are tiny spherical (balloon-like) sacs that are connected to the larger tubes of the lungs by alveolar ducts. (para 1-5b)

12. The left lung is smaller because it must leave room for the heart. (para 1-5c)

13. The mediastinum is found in the middle of the thorax, between the two pleural cavities. (para 1-5d)

14. When the volume of the chest cavity decreases, the air pressure inside the lungs increases and forces to flow out from the lungs. When the volume of the chest cavity increases, the air pressure inside the lungs decreases and causes air to flow in. (para 1-6a)

15. Muscles attached to the thoracic cage raise the rib cage during inhalation. (para 1-7a) 1-15

16. As the diaphragm contracts, the dome flattens and the diaphragm descends, thereby increasing the size of the thoracic cavity. This results in decreased air pressure within the thoracic cavity. The greater air pressure outside the body forces air into the lungs. (para 1-8a)

17. The respiratory center located in the brainstem. (para 1-9a)

18. Oxygen and carbon dioxide. (para 1-11)