Warm-Up

1. Warm-Up • Define words for 33.3

2. Ch. 33.3 – The Respiratory System

3. Background Information • All cells require a constant supply of oxygen for cellular respiration. • Recall C6H12O6 + 6O2 --> 6H2O + 6CO2 + ATP • Respiration means the process of gas exchange between a body and the environment. • Human respiratory system picks up oxygen from the air we inhale and releases carbon dioxide into the air we exhale. • With each breath air fills our lungs and gas exchange occurs there. • The circulatory system links the gas exchange to the rest of our body.

4. Structures of the Respiratory System

5. Consists of • The nose • The pharynx • The trachea • The bronchi • The lungs

6. The Nose • Air must be filtered, moistened and warmed before entering the lungs • Hairs lining the entrance to the nasal cavity trap large particles • Incoming air is warmed in the inner nasal cavity and sinuses. • Mucus is produced that moistens the air and further filters.

7. The Pharynx • A cavity at the back of the mouth • Also called the throat • Serves as a passageway for both air and food

8. The Larynx • After the pharynx air moves through the larynx to the trachea. • Contains two highly elastic folds of tissue known as the vocal cords. • These tissues give you the ability to produce sounds • When muscles pull the vocal cords together, the air moving between them causes the cords to vibrate and produce sounds.

9. The Trachea • Also known as the windpipe • When you shallow food or liquids, the epiglottis (a flap of tissue) covers the entrance to make the food or liquids go down the esophagus. • Lined with mucus that trap any inhaled particles. • Cilia lining the trachea sweep both the mucus and trapped particles upwards towards the pharynx. • From there, the mucus and particles can be swallowed or spit out • This helps keep the lungs clean and open form the important work of gas exchange.

10. The Lungs • Air then moves into the bronchi (singular: bronchus) – which are two large tubes in the chest cavity leading to each of the lungs. • The bronchus divides into smaller bronchi which then divides into the bronchioles (even smaller) • Bronchi and bronchioles are surrounded by smooth muscle tissue controlled by the autonomic nervous system • As the muscles contract and relax, the size of the passageways change. • Further divide until they reach the alveoli (singular: alveolus) • Alveoli are grouped into clusters • Surrounded by a delicate network of capillaries where the gas exchange occurs.

11. Gas Exchange and Transport

12. Background Information • Lungs contain about 150 million alveoli • Provide an enormous surface area for gas exchange • Oxygen and carbon dioxide are exchanged across the walls of the alveoli • Chemical properties of blood and red blood cells allow for efficient transport of gases throughout the body.

13. Gas Exchange • Air enters alveoli where the oxygen dissolves in he moisture on their inner surface and then diffuses across the thin capillary walls. • At the same time, carbon dioxide is diffusing from the blood into the air. • Air being breathed contains 21% O2 and 0.04% CO2. Exhaled air contains less than 15% O2 and 4% CO2. • Lungs remove ~1/4 of the oxygen for the breathed air and increase the CO2 level by 100x.

14. Transport • Oxygen binds to the hemoglobin which transport it • Hemoglobin also increases the efficiency of gas exchange. • Because hemoglobin actively binds to oxygen, the oxygen is removed for the plasma and this maintains the concentration gradient towards the blood. • Increase the blood’s oxygen-carrying capacity more than 60 times

15. Carbon dioxide is transported by 3 ways • Most enter the RBC and combine with H2O to form carbonic acid. • Some is dissolved in the plasma • Binds to hemoglobin and proteins in the plasma • This reverses the in the lungs, where the CO2 is released into the alveoli and exhaled.

16. Breathing

17. Background Information • Muscles are not connected to the lungs to aid in breathing. • Forces that drives breathing is air pressure, the diaphragm and muscles associated with the ribs. • Movements of the diaphragm and rib cage change air pressure in the chest cavity during inhalation and exhalation.

18. Inhalation • Lungs are in the pleural membranes (closed sacs) inside the chest cavity • At the bottom of the cavity is the diaphragm • When you inhale the diaphragm, contracts and flattens along with the muscle between the ribs contracting which raises the rib cage. • Increases the volume of the chest cavity • The increased volume in turn creates a partial vacuum inside the cavity and atmospheric pressure causes air to fill the lungs

19. Exhalation • During ordinary breathing, this is usually passive. • The rib cage and diaphragm relax; volume is decreased in the chest cavity; atmospheric pressure causes the air to leave. • When you need additional force, the muscles between the ribs and abdominal muscles contract vigorously as the diaphragm relaxes. • This only works because the chest cavity is sealed. • If the chest is punctured breathing is impossible.

20. Breathing and Homeostasis • You can control breathing whenever you want; however, the nervous system has final control over it • The medulla oblongata is the part of the brain stem where the breathing center is located. • Sensory neurons in or near the medulla and in large nearby blood vessels gather information on the CO2 levels in the blood and send that info to the medulla. • When stimulated, the center sends nerve impulses to the diagram and chest muscles to contract • The more CO2 the stronger the signals • If the CO2 reaches critical levels, you cannot keep from breathing.

21. Warm-Up for 1/9/12 • How is inhalation different from exhalation? • What evidence supports the fact that breathing is not entirely under conscious control?

22. Smoking and the Respiratory System

23. Effects on the Respiratory System • 3 most dangerous substances in tobacco smoke • Nicotine – an addictive stimulate that increase heart rate and blood pressure • Carbon monoxide – a poisonous gas that blocks hemoglobin from binding with the blood • Tar – contains at least 60 cancer causing compounds

24. Also paralyzes cilia in the trachea • This causes the inhaled particles to stick to the walls of the respiratory tract or to enter the lungs • Mucus cannot be pushed upwards • Irritation occurs from the accumulated mucus and particles and a smoker’s cough is triggers in an attempt to clear the passageways • Causes the lining of the respiratory tract to swell which reduces airflow to the alveoli

25. Diseases Caused by Smoking • Only 30% of male smokers live to age 80 while 55% of male nonsmokers do • Chronic Bronchitis • bronchi become inflamed and clogged with mucus • Treatment control symptoms but there is no cure • Daily activities become difficult

26. Emphysema • Loss of elasticity and eventual breakdown of lung tissue • Makes breathing difficult • Leads to a lack of oxygen and a build up of carbon dioxide • No cure but treatments include medication • Lung Cancer • Particularly deadly because by the time it is usually detected the cancer has spread • Few people that are diagnosed live more than 5 years • ~87% of lung cancer deaths are due to smoking

27. Other Effects of Smoking • Child of smokers are twice as likely as children of nonsmokers to develop asthma or other respiratory problems • Smoking while pregnant places the baby at risk which can lead to lifelong problems • Quitting smoking improves the health of the smoker