Chapter 22Chapter 22

RESPIRATION: THE EXCHANGE RESPIRATION: THE EXCHANGE

OF GASESOF GASES

Human Respiratory SystemHuman Respiratory System

Functions:Functions: Works closely with circulatory system, Works closely with circulatory system,

exchanging gases between air and blood:exchanging gases between air and blood: Takes up oxygen from air and supplies it to blood Takes up oxygen from air and supplies it to blood

(for cellular respiration).(for cellular respiration). Removal and disposal of carbon dioxide from blood Removal and disposal of carbon dioxide from blood

(waste product from cellular respiration).(waste product from cellular respiration).

Homeostatic Role:Homeostatic Role: Regulates blood pH.Regulates blood pH. Regulates blood oxygen and carbon dioxide Regulates blood oxygen and carbon dioxide

levels.levels.

Blood Transports Gases Between Lungs and Tissues

Human Respiratory SystemHuman Respiratory System

Components: Components:

Nasal cavity, throat (pharynx), larynx (voice box), Nasal cavity, throat (pharynx), larynx (voice box), trachea, bronchi, alveoli, and lungs.trachea, bronchi, alveoli, and lungs.

Pathway of Inhaled Air:Pathway of Inhaled Air: Nasal cavityNasal cavity Pharynx Pharynx (Throat)(Throat) Larynx Larynx (Voice Box)(Voice Box) Trachea Trachea (Windpipe)(Windpipe)

BronchiBronchi BronchiolesBronchioles Alveoli Alveoli ((Site of gas exchangeSite of gas exchange))

Exhaled air follows reverse pathway.Exhaled air follows reverse pathway.

Human Respiratory System

Human Respiratory SystemHuman Respiratory System

1. Nasal cavity: 1. Nasal cavity: Air enters nostrils, is filtered by Air enters nostrils, is filtered by hairs, warmed, humidified, and sampled for hairs, warmed, humidified, and sampled for odors as it flows through a maze of spaces. odors as it flows through a maze of spaces.

2. Pharynx (Throat):2. Pharynx (Throat): Intersection where pathway Intersection where pathway for air and food cross. Most of the time, the for air and food cross. Most of the time, the pathway for air is open, except when we swallow.pathway for air is open, except when we swallow.

3. Larynx (Voice Box):3. Larynx (Voice Box): Reinforced with cartilage. Reinforced with cartilage. Contains Contains vocal cordsvocal cords, which allow us to make , which allow us to make sounds by voluntarily tensing muscles.sounds by voluntarily tensing muscles. High pitched sounds:High pitched sounds: Vocal cords are tense, vibrate fast. Vocal cords are tense, vibrate fast. Low pitched sounds:Low pitched sounds: Vocal cords are relaxed, vibrate slowly. Vocal cords are relaxed, vibrate slowly. More prominent in males (More prominent in males (Adam’s appleAdam’s apple).).

Larynx or Voicebox Contains the Vocal Cords

Human Respiratory SystemHuman Respiratory System

4. Trachea (Windpipe): 4. Trachea (Windpipe): Rings of cartilage maintain Rings of cartilage maintain shape of trachea, to prevent it from closing. shape of trachea, to prevent it from closing. Forks into two bronchi.Forks into two bronchi.

5. Bronchi5. Bronchi (Sing. Bronchus):(Sing. Bronchus): Each bronchus leads Each bronchus leads into a lung and branches into smaller and smaller into a lung and branches into smaller and smaller bronchiolesbronchioles, resembling an inverted tree. , resembling an inverted tree.

6. Bronchioles:6. Bronchioles: Fine tubes that allow passage of air. Fine tubes that allow passage of air. Muscle layer constricts bronchioles. Epithelium Muscle layer constricts bronchioles. Epithelium of bronchioles is covered with cilia and mucus.of bronchioles is covered with cilia and mucus. Mucus traps dust and other particles.Mucus traps dust and other particles. Ciliary EscalatorCiliary Escalator: Cilia beat upwards and remove trapped : Cilia beat upwards and remove trapped

particles from lower respiratory airways. Rate about 1 to 3 cm particles from lower respiratory airways. Rate about 1 to 3 cm per hour.per hour.

Human Respiratory SystemHuman Respiratory System

AlveoliAlveoli (Sing. Alveolus):(Sing. Alveolus): Grapelike clusters of tiny Grapelike clusters of tiny air sacs with very thin elastic walls through air sacs with very thin elastic walls through which gas exchange occurs.which gas exchange occurs. Oxygen in air enters blood in capillaries.Oxygen in air enters blood in capillaries. Carbon dioxide in blood enters air in alveoli.Carbon dioxide in blood enters air in alveoli.

There are several million alveoli in the human There are several million alveoli in the human lungs, with a total surface roughly equivalent to a lungs, with a total surface roughly equivalent to a tennis court.tennis court.

The walls of the alveoli are very delicate.The walls of the alveoli are very delicate.

Alveolar macrophagesAlveolar macrophages are phagocytic cells that are phagocytic cells that swallow inhaled particles (dust, bacteria, etc.) swallow inhaled particles (dust, bacteria, etc.) and digest them.and digest them.

Structure of Lung Alveoli

Lung Alveoli Are The Site of Gas Exchange

Exchange of Gases Occurs in Alveoli

Breathing Ventilates the LungsBreathing Ventilates the Lungs

Breathing:Breathing: Alternation of inhalation and Alternation of inhalation and exhalation. Supplies our lungs with oxygen rich exhalation. Supplies our lungs with oxygen rich air, and expels excess carbon dioxide.air, and expels excess carbon dioxide.

Inhalation:Inhalation: Diaphragm contracts, moving Diaphragm contracts, moving downward and causing rib cage, chest cavity, and downward and causing rib cage, chest cavity, and lungs to expand. Air rushes in, due to decrease in lungs to expand. Air rushes in, due to decrease in internal lung pressure as lungs expand.internal lung pressure as lungs expand.

Exhalation:Exhalation: Diaphragm relaxes, moving upwards Diaphragm relaxes, moving upwards and causing rib cage, chest cavity, and lungs to and causing rib cage, chest cavity, and lungs to contract. Air rushes out, due to the increase in contract. Air rushes out, due to the increase in internal lung pressure as lungs contract.internal lung pressure as lungs contract.

Breathing is controlled by centers in the nervous Breathing is controlled by centers in the nervous system to keep up with body’s demands.system to keep up with body’s demands.

Human Breathing: Inhalation and Exhalation

Human Breathing is Automatically Controlled

Hemoglobin helps transport COHemoglobin helps transport CO22 and buffer blood and buffer blood

Hemoglobin is found in red blood cellsHemoglobin is found in red blood cells

Functions:Functions: Transports oxygenTransports oxygen Transport carbon dioxideTransport carbon dioxide Helps buffer bloodHelps buffer blood

As carbon dioxide is picked up from tissues it is As carbon dioxide is picked up from tissues it is converted into carbonic acid:converted into carbonic acid:

COCO22 + H + H22O <-----> HO <-----> H22COCO33 <----> H <----> H++ + HCO + HCO3 3 --

Carbon Carbon Carbonic acidCarbonic acid Carbonate ion Carbonate iondioxidedioxide

Hemoglobin picks up most H Hemoglobin picks up most H ++ ions, so they don’t ions, so they don’t acidify the blood.acidify the blood.

Blood Transports Gases to Between Lungs and Tissues

Hemoglobin Loading and Unloading of Oxygen

Hemoglobin Transports Gases and Helps Buffer Blood

Diseases of the Respiratory SystemDiseases of the Respiratory System Respiratory rate: 10 to 14 inhalations/minute.Respiratory rate: 10 to 14 inhalations/minute.

In one day, an average human:In one day, an average human: Breathes 20,000 timesBreathes 20,000 times

Inhales 35 pounds of airInhales 35 pounds of air

Most of us breathe in air that is heavily Most of us breathe in air that is heavily

contaminated with solid particles, ozone, sulfur contaminated with solid particles, ozone, sulfur

oxide, carbon monoxide, nitrogen oxides, and many oxide, carbon monoxide, nitrogen oxides, and many

other damaging chemicals.other damaging chemicals.

Breathing contaminated air can cause a number of Breathing contaminated air can cause a number of

diseases including asthma, bronchitis, emphysema, diseases including asthma, bronchitis, emphysema,

and lung cancer.and lung cancer.

Diseases of the Respiratory SystemDiseases of the Respiratory System Cigarette smoke is one of the worse air pollutants.Cigarette smoke is one of the worse air pollutants.

Over 1 million people start smoking every year.Over 1 million people start smoking every year. Kills about 350,000 people every year in U.S.Kills about 350,000 people every year in U.S. Contains 4000 different chemicals.Contains 4000 different chemicals. Each cigarette smoked subtracts about 5 minutes from Each cigarette smoked subtracts about 5 minutes from

life expectancy.life expectancy. Cigarette smoke Cigarette smoke paralyzes ciliaparalyzes cilia in airways, preventing in airways, preventing

them from removing debris and from protecting delicate them from removing debris and from protecting delicate alveoli.alveoli.

Frequent coughing is the only way airways can clean Frequent coughing is the only way airways can clean themselves.themselves.

Cigarette smoke also causes fetal damage, which can Cigarette smoke also causes fetal damage, which can result in miscarriage, premature birth, low birth weight, result in miscarriage, premature birth, low birth weight, and poor development.and poor development.

Diseases of the Respiratory SystemDiseases of the Respiratory System Asthma:Asthma: Condition in which breathing is Condition in which breathing is

impaired by constriction of bronchi and impaired by constriction of bronchi and bronchioles, cough, and thick mucus secretions. bronchioles, cough, and thick mucus secretions. The severity and incidence of asthma has risen The severity and incidence of asthma has risen dramatically in recent years, especially in dramatically in recent years, especially in children. May be fatal if not treated.children. May be fatal if not treated.

Causes:Causes: Attacks may be precipitated by Attacks may be precipitated by inhalation of allergens (e.g.: pollen, cats, and inhalation of allergens (e.g.: pollen, cats, and cockroach proteins), pollutants, infection, or cockroach proteins), pollutants, infection, or emotional stress.emotional stress.

Treatment:Treatment: Alleviates symptoms (e.g.: immuno- Alleviates symptoms (e.g.: immuno-suppressors, bronchodilators), but is not a cure.suppressors, bronchodilators), but is not a cure.

Diseases of the Respiratory SystemDiseases of the Respiratory System Bronchitis:Bronchitis: Inflammation of the mucous Inflammation of the mucous

membranes of the bronchi. May present with membranes of the bronchi. May present with cough, fever, chest or back pain, and fatigue.cough, fever, chest or back pain, and fatigue.

Causes:Causes: Associated with smoking, pollution, and Associated with smoking, pollution, and bacterial or viral infections.bacterial or viral infections.

Pneumonia:Pneumonia: Acute inflammation of the lungs. Acute inflammation of the lungs. Symptoms include high fever, chills, headache, Symptoms include high fever, chills, headache, cough, and chest pain. cough, and chest pain.

Causes: Causes: Bacterial, fungal, or viral infections.Bacterial, fungal, or viral infections.

Treatment:Treatment: Antibiotics or other antimicrobials. Antibiotics or other antimicrobials.

Diseases of the Respiratory SystemDiseases of the Respiratory System Emphysema:Emphysema: Permanent and irreversible Permanent and irreversible

destruction of alveolar walls, resulting in loss of destruction of alveolar walls, resulting in loss of lung elasticity and gas exchange surface. lung elasticity and gas exchange surface.

Symptoms include shortness of breath, difficulty Symptoms include shortness of breath, difficulty exhaling, cough, weakness, anxiety, confusion, exhaling, cough, weakness, anxiety, confusion, heart failure, lung edema (swelling), and heart failure, lung edema (swelling), and respiratory failure.respiratory failure.

Causes:Causes: SmokingSmoking, pollution, old age, and , pollution, old age, and infections.infections.

Treatment:Treatment: Oxygen to help breathing. No cure. Oxygen to help breathing. No cure.

Diseases of the Respiratory SystemDiseases of the Respiratory System Lung Cancer:Lung Cancer: Cancerous growth that invades Cancerous growth that invades

and destroys lung tissue. Very high fatality rate. and destroys lung tissue. Very high fatality rate.

Symptoms include bloody sputum, persistent Symptoms include bloody sputum, persistent cough, difficulty breathing, chest pain, and cough, difficulty breathing, chest pain, and repeated attacks of bronchitis or pneumonia.repeated attacks of bronchitis or pneumonia.

Causes:Causes: Smoking Smoking (50% of all cases) and pollution (50% of all cases) and pollution (radon, asbestos). Smokers are 10 times more (radon, asbestos). Smokers are 10 times more likely to develop lung cancer than nonsmokers.likely to develop lung cancer than nonsmokers.

Treatment:Treatment: Surgery is most effective, but only Surgery is most effective, but only 50% of all lung cancers are operable by time of 50% of all lung cancers are operable by time of detection. Other treatments include radiation detection. Other treatments include radiation and chemotherapy.and chemotherapy.

Human Fetus Exchanges Gases with Mother’s Blood through the Placenta