Download Respiratory System

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).
Homeostatic Role:
Regulates blood pH.
 Regulates blood oxygen and carbon dioxide
levels.

Blood Transports Gases Between Lungs and Tissues
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.
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.
Hemoglobin helps transport CO2 and buffer blood
Hemoglobin is found in red blood cells
Functions:



Transports oxygen
Transport carbon dioxide
Helps buffer blood
As carbon dioxide is picked up from tissues it is converted
into carbonic acid:
CO2 + H2O <-----> H2CO3 <----> H+ + HCO3 Carbon
ion
dioxide
Carbonic acid
Carbonate
Hemoglobin picks up most H + ions, so they don’t acidify the
blood.
Hemoglobin Loading and Unloading of Oxygen
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.

Diseases of the Respiratory System
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.:
immuno-suppressors, bronchodilators), but is
not a cure.


Diseases of the Respiratory System
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.

Diseases of the Respiratory System
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.

Diseases of the Respiratory System
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.