Chapter 16 Respiratory System

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Introduction Chapter 16 Respiratory System The respiratory system consists of tubes that filter incoming air and transport it to alveoli where gases are exchanged.

1 Introduction Chapter 16 Respiratory System The respiratory system consists of tubes that filter incoming air and transport it to alveoli where gases are exchanged. Think pair share: what organs are associated with the respiratory system? The entire process of exchanging gases between the atmosphere and body cells is RESPIRATION consists of: ventilation, gas exchange between blood and lungs, gas transport in the bloodstream, gas exchange between the blood and body cells, cellular respiration Organs of the Respiratory System Nose provides entrance for air, coarse hairs filter. Nasal Cavity Nasal conchae divide nasal cavity into passageways, lined with mucous membranes; increase surface area to warm and filter air. FIG Particles in mucus carried to pharynx by cilia, swallowed, carried to stomach where gastric juice destroys microorganisms

5/13/2014 Pharynx common passageway for air and food

16-8 16-7 Larynx (voicebox) helps keep particles from

composed of framework of muscles and cartilage bound by

Vocal Cords: two pairs of muscle folds and connective

2 5/13/2014 Pharynx common passageway for air and food (throat) Aids in producing sounds for speech Larynx (voicebox) helps keep particles from entering the trachea houses vocal cords. composed of framework of muscles and cartilage bound by elastic tissue. Vocal Cords: two pairs of muscle folds and connective tissue covered with mucous membrane Changing tension controls pitch, Changing force of air vibrating cords increases loudness FIG

16-14 Bronchial Tree branched tubes leading from the trachea to the alveoli First: R and L primary Bronchi Then: subdivide to Bronchioles Then: alveolar ducts Finally: alveoli.

3 Trachea (windpipe) extends downward anterior to esophagus into thoracic cavity splits into right and left bronchi. Inner wall lined with ciliated mucous membranes that trap foreign particles. supported by 20 cartilaginous rings Bronchial Tree branched tubes leading from the trachea to the alveoli First: R and L primary Bronchi Then: subdivide to Bronchioles Then: alveolar ducts Finally: alveoli. gas exchange between blood and air in alveoli through thin epithelial membranes (simple squamous) Lungs R & L enclosed by diaphragm & thoracic cage. bronchus & large blood vessels enter each. Right lung: 3 lobes Left lung: 2 lobes lobes contain air passages, alveoli, nerves, blood vessels, lymphatic vessels, and connective tissues

Breathing Mechanism Ventilation (breathing): movement of air in and out of the lungs composed of inspiration and expiration. Inspiration Atmospheric pressure moves air into the lungs.

Breathing Mechanism Inspiration Increasing size of thoracic cavity decreases Air pressure inside lungs due surface tension between two layers of pleura causes lungs to expand with chest wall.

4 Breathing Mechanism Ventilation (breathing): movement of air in and out of the lungs composed of inspiration and expiration. Inspiration Atmospheric pressure moves air into the lungs. as pressure inside lungs decreases, higher pressure air from outside flows in. Breathing Mechanism Inspiration Increasing size of thoracic cavity decreases Air pressure inside lungs due surface tension between two layers of pleura causes lungs to expand with chest wall. Muscles involved: diaphragm & external intercostal muscles. Surfactant keeps alveoli from sticking to each other so don t collapse during low pressure Breathing Mechanism Expiration Mainly due to elastic recoil of lungs and muscle tissues and surface tension within alveoli. Forced expiration aided by thoracic and abdominal wall muscles Respiratory Air Volumes and Capacities Respiratory cycle: One inspiration followed by expiration Tidal volume: the amount of air that enters or leaves the lungs during one respiratory cycle Vital capacity: maximum volume of air that can be moved into and out of the lungs Total lung capacity: Vital capacity + residual volume

Control of Breathing Normal breathing is rhythmic, involuntary act even though the muscles are under voluntary control.

Inactive during expiration Neurons in pons are inhibitory and help regulate the rate of breathing emitted from medulla.

17 increase in these triggers chemoreceptors which signal respiratory center, respiratory rate increases. as CO 2 levels drop, breathing rate decreases.

5 Control of Breathing Normal breathing is rhythmic, involuntary act even though the muscles are under voluntary control. Respiratory Center: Groups of neurons in pons and medulla (brain stem) Emit bursts of impulses that signal diaphragm and other inspiratory muscles. Inactive during expiration Neurons in pons are inhibitory and help regulate the rate of breathing emitted from medulla Other factors affecting breathing Chemosensitive area in brain stem (medulla) detect changes in CO 2 and H+ ions in cerebrospinal fluid (CSF) FIG increase in these triggers chemoreceptors which signal respiratory center, respiratory rate increases. as CO 2 levels drop, breathing rate decreases Other factors affecting breathing Carotid and Aortic bodies contain chemoreceptors that detect blood oxygen levels and send signals to respiratory centers in brain stem. FIG Takes extremely low levels to trigger therefore, O 2 levels minimal in controlling respiration Hyperventilation: breathing rapidly and deeply Lowers CO 2 levels so takes longer for respiratory centers to be triggered Can hold breath slightly longer

Alveolar Gas Exchange Alveoli tiny sacs clustered at distal ends of the alveolar ducts. only sites of gas exchange between atmosphere and blood.

16-31 16-32 Diffusion across the Respiratory Membrane Gases diffuse from high pressure to low pressure. FIG. 16.10 factors favoring diffusion; more surface area, shorter distance, solubility of gases, steeper partial pressure gradient.

6 Alveolar Gas Exchange Alveoli tiny sacs clustered at distal ends of the alveolar ducts. only sites of gas exchange between atmosphere and blood. Respiratory Membrane consists of epithelial cells of the alveolus, the endothelial cells of capillaries, and fused basement membranes of these. Gas exchange occurs across this membrane Diffusion across the Respiratory Membrane Gases diffuse from high pressure to low pressure. FIG factors favoring diffusion; more surface area, shorter distance, solubility of gases, steeper partial pressure gradient Gas transport Gases are transported with molecules in blood or dissolved in plasma. Oxygen Transport 98% of oxygen is carried in blood bound to Hemoglobin of red blood cells, producing Oxyhemoglobin. Oxyhemoglobin unstable where oxygen concentration is low, so gives up its oxygen easily. Oxygen Transport More oxygen is released as blood concentration of CO 2 increases. O 2 deficiency at tissues is called hypoxia variety of causes: Decreased arterial pressure Decreased ability of blood to transport Inadequate blood flow Cellular defects 6

CO 2 reacts with water to form carbonic acid (H 2 CO 3 ) RBC s contain carbonic anhydrase which

7 Carbon Dioxide Transport CO 2 dissolved in blood plasma as Carbaminohemoglobin or Most CO 2 is transported in form of bicarbonate (HCO 3 -). CO 2 reacts with water to form carbonic acid (H 2 CO 3 ) RBC s contain carbonic anhydrase which speeds this reaction. H 2 CO 3 then dissociates releasing H+ and HCO 3-7 Carbaminohemoglobin also releases its CO 2 which diffuses from blood into alveolar air. 7

Breathing: The normal rate is about 14 to 20 times a minute. Taking in of air is called Inspiration and the forcing out of air is called Expiration.

Breathing: The normal rate is about 14 to 20 times a minute. Taking in of air is called Inspiration and the forcing out of air is called Expiration. Biology 12 Respiration Divisions of Respiration Breathing: entrance and exit of air into and out of the lungs External Respiration: exchange of gases(o2 and CO2) between air (in alveoli) and blood Internal