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UNIFYING CONCEPTS OF ANIMAL RESPIRATION Cells using cellular respiration need a steady supply of oxygen and must continuously dispose of CO 2 The respiratory.

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Presentation on theme: "UNIFYING CONCEPTS OF ANIMAL RESPIRATION Cells using cellular respiration need a steady supply of oxygen and must continuously dispose of CO 2 The respiratory."— Presentation transcript:

1 UNIFYING CONCEPTS OF ANIMAL RESPIRATION Cells using cellular respiration need a steady supply of oxygen and must continuously dispose of CO 2 The respiratory system promotes this gas exchange. © 2013 Pearson Education, Inc. Environment Cell GlucoseOxygen WaterEnergy Cellular respiration Carbon dioxide C 6 H 12 O 6 6 O 2 6 CO 2 6 H 2 O ATP CO 2 O2O2

2 The Human Respiratory System Gas exchange occurs at the respiratory surface within the lungs –A large, moist internal surface folded into the body –open to the air only through narrow tubes –The circulatory system transports gases between the respiratory surface (alveoli) and the rest of the body Lungs (localized internal organs) Model of a pair of human lungs

3 The Human Respiratory System The human respiratory system has three phases of gas exchange: 1. breathing, the ventilation of the lungs by alternate inhalation and exhalation, 2. transport of oxygen from the lungs to the rest of the body via the circulatory system, and 3. diffusion of oxygen from the blood and release of CO 2 into the blood by cells of the body. © 2013 Pearson Education, Inc.

4 Figure 23.UN02 Pulmonary arteries CO 2 O 2 -rich blood O2O2 Pulmonary veins Pulmonary circuit O 2 -poor blood Capillaries Systemic circuit Heart Capillaries Aorta Arteries Arterioles Venae cavae Veins Venules

5 The Human Respiratory System The human respiratory system: -has a series of passageways that carry air into and out of the lungs -It warms & moistens the air moving through it -It is lined by epithelial cells: mucus traps dust and microorganisms cilia sweep mucus up toward pharynx © 2013 Pearson Education, Inc.

6 Air Nostrils – into nasal cavity Mouth – into oral cavity Pharynx Air filtered by hairs & mucus Air warmed & humidified common chamber for air & food Esophagus food to stomach Larynx (voice box) Trachea (windpipe) reinforced with semicircular bands of stiff hyaline cartilage Flexible tube with walls reinforced with semicircular bands of stiff hyaline cartilage Muscles in the voice box stretch vocal chords & exhalation passes air over them to produce sounds Human respiratory system

7 Trachea Bronchus (to right lung) In the lungs In the lung the bronchi branch into numerous, even smaller tubes called bronchioles Bronchioles Lead to alveoli (pl.) (air sacs) (to left lung) Bronchus Gas exchange

8 Figure 23.19a Larynx (voice box) Trachea (windpipe) (a) Overview of the human respiratory system Pharynx Right lung Bronchus Bronchiole Diaphragm Esophagus Nasal cavity Left lung Heart

9 Figure 23.19b (b) The structure of alveoli (air sacs) 1.5 to 2.5 million are packed into each lung Bronchiole Blood capillaries From heart To heart Alveoli O 2 -rich blood O 2 -poor blood O2O2 CO 2 Respiratory surface is thin and moist & allows for rapid diffusion -Alveoli: simple squamous epithelium -Pulmonary capillaries: simple squamous epithelium Pulmonary capillaries surround alveoli

10 from pulmonary artery alveolar membrane respiratory membrane to pulmonary vein (air)CO 2 O2O2 capillary fluid Oxygen diffuses into red blood cells Carbon dioxide diffuses into alveolus Gas exchange between alveoli and capillaries Gases can dissolve & diffuse between the lungs and the circulatory system

11 Lungs Lungs are protected within an airtight chest cavity The chest cavity is bound by: –neck muscles & connective tissue on the top –muscular thin diaphragm on the bottom The rib cage surrounds and protects the lungs

12 Taking a Breath Breathing is the alternating process of inhalation and exhalation. During inhalation –upward movement of the ribs –downward movement of the diaphragm (contraction) –volume of the lungs increases/chest is expanded –Air pressure in lungs drops below air pressure of atmosphere Air moves into the lungs by negative pressure breathing (air moves from high to low pressure)

13 Taking a Breath Automatic exhalation of air occurs when muscles that cause inhalation are relaxed and the chest cavity is restricted –inward movement of the ribs –upward movement of the diaphragm –the volume of the lungs decreases –air pressure in the lungs increases –air moves out of the respiratory system

14 Figure Inhalation (Air pressure is higher in atmosphere than in lungs.) Exhalation (Air pressure is lower in atmosphere than in lungs.) Diaphragm relaxes (moves up) Diaphragm contracts (moves down) Rib cage expands as rib muscles contract Rib cage gets smaller as rib muscles relax Air inhaled Air exhaled Lung

15 Breathing can be controlled –consciously, as you deliberately take a breath, or –unconsciously Breathing control centers in the brain stem –automatically control breathing most of the time –regulate breathing rate in response to CO 2 levels in the blood Taking a Breath © 2013 Pearson Education, Inc.

16 Figure CO 2 levels in the blood rise as a result of exercise. Brain Breathing control centers in the brain monitor the rising CO 2 levels in the blood. Breathing control centers Nerve signals trigger contraction of muscles to increase breathing rate and depth. Rib muscles Diaphragm 123 Signals a need for more oxygen

17 The Role of Hemoglobin in Gas Transport The human respiratory system –takes in O 2 –expels CO 2, but –relies on the circulatory system to shuttle these gases between the lungs and the bodys cells. Alveolus Air spaces Capillaries of lung Tissue capillaries CO 2 -rich, O 2 -poor blood O 2 -rich, CO 2 -poor blood O 2 in inhaled air CO 2 in exhaled air CO 2 O2O2 Tissue cells throughout body CO 2 O2O2 Heart O2O2 CO 2 O2O2 Interstitial fluid

18 Oxygen does not readily dissolve in blood. –Solution: Oxygen is carried in hemoglobin molecules within red blood cells The Role of Hemoglobin in Gas Transport Heme group Iron atom Polypeptide chain O 2 loaded in lungs O 2 unloaded in tissues O2O2 O2O2

19 How Smoking Affects the Lungs Breathing exposes your respiratory tissues to potentially damaging chemicals © 2013 Pearson Education, Inc. Tobacco smoke –damages the cells that line the bronchi and trachea –interferes with the normal cleansing mechanism of the respiratory system: more toxin-laden smoke particles reach & damage the lungs alveoli

20 Smoking –kills half of all people who smoke, about 440,000 Americans every year, –causes 90% of all lung cancer (one of the deadliest forms of cancer), and How Smoking Affects the Lungs (a) Healthy lung (nonsmoker) (b) Cancerous lung (smoker)


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