Transcript Human Respiratory System

Respiratory
System
Chapter 22
Human Respiratory System
Functions:
• Works closely with circulatory system,
exchanging gases between air and blood:
• Takes up oxygen from air and supplies it to
blood (for cellular respiration).
• Removal and disposal of carbon dioxide from
blood (waste product from cellular
respiration).
Human Respiratory System
Components:
Nasal cavity, throat (pharynx), larynx (voice box),
trachea, bronchi, alveoli, and lungs.
Pathway of Inhaled Air:
Nasal cavity
Pharynx (Throat)
Larynx (Voice Box)
Trachea (Windpipe)
Bronchi
Bronchioles
Alveoli (Site of gas exchange)
Exhaled air follows reverse pathway.
• https://www.youtube.com/watch?v=9MDn5GgyxyU
Vocal Cord action
Human Respiratory System
1. Nasal cavity: Air enters nostrils, is filtered by hairs, warmed,
humidified, and sampled for odors as it flows through a
maze of spaces.
2. Pharynx (Throat): Intersection where pathway for air and
food cross. Most of the time, the pathway for air is open,
except when we swallow.
3. Larynx (Voice Box): Reinforced with cartilage. Contains vocal
cords, which allow us to make sounds by voluntarily
tensing muscles.
• High pitched sounds: Vocal cords are tense, vibrate
fast.
• Low pitched sounds: Vocal cords are relaxed, vibrate
slowly.
• More prominent in males (Adam’s apple).
Human Respiratory System
4. Trachea (Windpipe): Rings of cartilage maintain shape of
trachea, to prevent it from closing. Forks into two bronchi.
5. Bronchi (Sing. Bronchus): Each bronchus leads into a lung
and branches into smaller and smaller bronchioles,
resembling an inverted tree.
6. Bronchioles: Fine tubes that allow passage of air. Muscle
layer constricts bronchioles. Epithelium of bronchioles is
covered with cilia and mucus.
• Mucus traps dust and other particles.
• Ciliary Escalator: Cilia beat upwards and remove
trapped particles from lower respiratory airways. Rate
about 1 to 3 cm per hour.
Breathing Ventilates the Lungs
Breathing: Alternation of inhalation and exhalation. Supplies our
lungs with oxygen rich air, and expels excess carbon dioxide.
 Inhalation: Diaphragm contracts, moving downward and
causing rib cage, chest cavity, and lungs to expand. Air rushes
in, due to decrease in internal lung pressure as lungs expand.
 Exhalation: Diaphragm relaxes, moving upwards and causing
rib cage, chest cavity, and lungs to contract. Air rushes out,
due to the increase in internal lung pressure as lungs
contract.
Breathing is controlled by centers in the nervous system to
keep up with body’s demands.
Table 16.3
Terms Used to Describe Lung Volumes and
Capacities
Term
Definition
Lung Volumes
The four nonoverlapping components of the total lung
capacity
The volume of gas inspired or expired in an unforced
respiratory cycle
The maximum volume of gas that can be inspired during
forced breathing in addition to tidal volume
The maximum volume of gas that can be expired during
forced breathing in addition to tidal volume
The volume of gas remaining in the lungs after a maximum
expiration
Measurements that are the sum of two or more lung volumes
The total amount of gas in the lungs after a maximum
inspiration
The maximum amount of gas that can be expired after a
maximum inspiration
The maximum amount of gas that can be inspired after a
normal tidal expiration
The amount of gas remaining in the lungs after a normal tidal
expiration
Tidal volume
Inspiratory reserve volume
Expiratory reserve volume
Residual volume
Lung Capacities
Total lung capacity
Vital capacity
Inspiratory capacity
Functional residual capacity
Human Fetus Exchanges Gases with
Mother’s Blood through the Placenta
Diseases of the Respiratory System
• Respiratory rate: 10 to 14 inhalations/minute.
• In one day, an average human:
• Breathes 20,000 times
• Inhales 35 pounds of air
• Most of us breathe in air that is heavily contaminated with solid
particles, ozone, sulfur oxide, carbon monoxide, nitrogen
oxides, and many other damaging chemicals.
• Breathing contaminated air can cause a number of diseases
including asthma, bronchitis, emphysema, and lung cancer.
Diseases of the Respiratory System
• Cigarette smoke is one of the worse air pollutants.
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Over 1 million people start smoking every year.
Kills about 350,000 people every year in U.S.
Contains 4000 different chemicals.
Each cigarette smoked subtracts about 5 minutes
from life expectancy.
• Cigarette smoke paralyzes cilia in airways,
preventing them from removing debris and from
protecting delicate alveoli.
• Frequent coughing is the only way airways can clean
themselves.
• Cigarette smoke also causes fetal damage, which can
result in miscarriage, premature birth, low birth
weight, and poor development.
Asthma: Condition in which breathing is impaired
by constriction of bronchi and bronchioles,
cough, and thick mucus secretions. The severity
and incidence of asthma has risen dramatically in
recent years, especially in children. May be fatal
if not treated.
Causes: Attacks may be precipitated by inhalation
of allergens (e.g.: pollen, cats, and cockroach
proteins), pollutants, infection, or emotional
stress.
Treatment: Alleviates symptoms (e.g.: immunosuppressors, bronchodilators), but is not a cure.
• Bronchitis: Inflammation of the mucous
membranes of the bronchi. May present with
cough, fever, chest or back pain, and fatigue.
Causes: Associated with smoking, pollution, and
bacterial or viral infections.
• Pneumonia: Acute inflammation of the lungs.
Symptoms include high fever, chills,
headache, cough, and chest pain.
Causes: Bacterial, fungal, or viral infections.
Treatment: Antibiotics or other
antimicrobials.
Emphysema: Permanent and irreversible destruction
of alveolar walls, resulting in loss of lung elasticity
and gas exchange surface.
Symptoms include shortness of breath, difficulty
exhaling, cough, weakness, anxiety, confusion, heart
failure, lung edema (swelling), and respiratory
failure.
Causes: Smoking, pollution, old age, and infections.
Treatment: Oxygen to help breathing. No cure.
Lung Cancer: Cancerous growth that invades and
destroys lung tissue. Very high fatality rate.
Symptoms include bloody sputum, persistent cough,
difficulty breathing, chest pain, and repeated attacks
of bronchitis or pneumonia.
Causes: Smoking (50% of all cases) and pollution (radon,
asbestos). Smokers are 10 times more likely to
develop lung cancer than nonsmokers.
Treatment: Surgery is most effective, but only 50% of all
lung cancers are operable by time of detection.
Other treatments include radiation and
chemotherapy.