L05 Flashcards
Functions of the respiratory system
Consists of two tracts
* Upper respiratory tract
* Lower respiratory tract
* Supplies the body with oxygen
and eliminates carbon dioxide
(ventilation).
upper respiratory tract
- Consists of the nose, sinuses and nasal passages, pharynx,
tonsils and adenoids, larynx, and trachea.
● Warms and filters inspired air.
the nose
A passageway for air to pass to and from the lungs.
● Filters, humidifies, and warms the air as it is inhaled.
● Air entering the nostrils is deflected upward to the roof of the
nose before it reaches the nasopharynx.
● Ciliated mucous membranes (nasal mucosa) trap all the dust
and microorganisms in the inhaled air.
paranasal sinuses
ncludes 4 pairs of bony cavities.
● These airspaces are connected by ducts that drain into the nasal cavity.
● The sinuses are named by their location: frontal, ethmoidal, sphenoidal, and
maxillary.
● Prominent function: a resonating center for speech.
● Common site for infection.
pharynx, tonsils and adenoids
includes 4 pairs of bony cavities.
● These airspaces are connected by ducts that drain into the nasal cavity.
● The sinuses are named by their location: frontal, ethmoidal, sphenoidal, and
maxillary.
● Prominent function: a resonating center for speech.
● Common site for infection.
larynx
A cartilaginous epithelium-lined structure that connects the pharynx and
trachea.
● Also known as the “voice organ” or “voice box”.
● Protects the lower airway from foreign substances and facilitates coughing.
● Consists of the following:
○ Epiglottis: A valve flap of cartilage that covers the opening to the larynx
during swallowing
○ Glottis: The opening between the vocal cords in the larynx
○ Thyroid cartilage: The largest of the cartilage structures; part of it forms
the Adam’s apple
○ Cricoid cartilage: The only complete cartilaginous ring in the larynx
(located below the thyroid cartilage)
○ Arytenoid cartilages: Used in vocal cord movement with the thyroid
cartilage
○ Vocal cords: Ligaments controlled by muscular movements that produce
sounds; located in the lumen of the larynx
trachea
Windpipe
● Composed of smooth muscle with c-shaped rings of
cartilage.
● The cartilage rings give firmness to the wall of the trachea.
● The passageway between the larynx and the bronchi.
lower respiratory tract
Consists of the lungs which
include the bronchial and
alveolar structures.
● Responsible for gas
exchange.
the lungs
Paired elastic structures enclosed in the thoracic cage.
● Ventilation requires movement of the walls of the thoracic cage and floor – the
diaphragm.
● The inspiratory phase of respiration requires energy. The expiratory phase is
normally passive.
● Pleura: a serous membrane lining the lungs and walls of the thorax.
○ Visceral pleura: covers the lungs.
○ Parietal pleura: lines the thorax.
● Pleural fluid between the visceral and parietal pleura acts as a lubricant and
permits smooth motion of the lungs.
the lungs
Mediastinum: the middle of the thorax, between the pleural sacs that contain the
lungs.
○ Contains all thoracic tissue outside of the lungs.
● Lobes: each lung is divided into lobes.
○ Right lung: upper, middle, and lower lobes (3)
○ Left lung: upper and lower lobes (2)
● Bronchi & bronchioles: there are several divisions of the bronchi within each
lobe of the lung.
○ Bronchi: surrounded by connective tissue containing arteries, lymphatics,
and nerves.
○ Bronchioles: contain no cartilage in their walls. Patency depends on the
elastic recoil of the surrounding smooth muscle and alveolar pressure.
● Both bronchi & bronchioles are lined with cells covered with cilia. These cilia
propels mucus and foreign substances away from the lungs.
the lungs
Respiratory bronchioles: the transitional passageways between the conducting
airways and gas exchange airways.
○ Further leading into the alveolar ducts alveolar sacs alveoli
● Physiological dead space: the conducting airways (containing 150 mL of air)
that does not participate in gas exchange.
● Alveoli: where oxygen and carbon dioxide exchange takes place.
respiratory physiology
Most cells in the body obtain their energy from chemical reactions involving
oxygen and the elimination of carbon dioxide.
● There are three steps in the process of oxygenation:
○ Ventilation
○ Perfusion
○ Diffusion
ventilation
The process of moving gases into and out of the lungs.
● Requires coordination of the muscular and elastic properties of the lung and
thorax.
● The major inspiratory muscle of respiration is the diaphragm.
○ Controlled by the phrenic nerve
perfusion
The ability of the cardiovascular system to pump oxygenated blood to the
tissues and return deoxygenated blood to the lungs.
diffusion
Responsible for moving the molecules from one area to another.
○ From an area of higher concentration to an area of lower concentration.
● Diffusion of respiratory gases occurs at the alveolocapillary membrane.
○ Rate of diffusion can be affected by the thickness of the membrane.
● Patients with pulmonary edema, pulmonary infiltrates, or a pulmonary effusion
have an increased thickness of the alveolocapillary membrane, resulting in
slowed diffusion, slowed gas exchange, and impaired delivery of oxygen to
tissues.
● Surface area of the membrane can be altered as a result of chronic disease.
work of breathing
Inspiration: an active process stimulated by receptors in the aorta.
● Expiration: a passive process depending on the elastic-recoil properties of
the lungs.
● Surfactant: a chemical produced by the lungs that maintains the surface
tension of the alveoli – preventing them from collapsing.
○ Atelectasis: the collapse of the alveoli that prevents normal gas
exchange.
● Compliance: the ability of the lungs to distend or expand in response to
increase intra-alveolar pressure.
● Airway resistance: the pressure difference between the mouth and the
alveoli in relation to the rate of flow of inspired gas.
● Decreased lung compliance, increased airway resistance, active respiration, or
respiratory gas exchange
Occurs in the alveoli and capillaries of the body tissues.
● In the lungs:
○ Oxygen is transferred from the lungs to the blood.
○ Carbon dioxide is transferred from the blood to the alveoli to be exhaled.
● In the tissues:
○ Oxygen is transferred from the blood to the tissues.
○ Carbon dioxide is transferred from the tissues to the blood to return to
the alveoli to be exhaled.
● These transfers are dependent on diffusion!
respiratory gas transport
Oxygen Transport:
○ Transported by hemoglobin
○ Hemoglobin molecules combine with oxygen to form oxyhemoglobin.
○ Hemoglobin and oxygen dissociate – freeing oxygen to enter the tissues.
● Caron dioxide transport:
○ Diffuses into red blood cells
○ Reduced hemoglobin (deoxyhemoglobin) can combine with carbon
dioxide easily, therefore; venous blood transports most of the carbon
dioxide.
regulation of respiration
Necessary to ensure sufficient oxygen intake and carbon dioxide elimination to
meet the body’s demands.
● Neural and chemical regulators control the process of respiration.
● Neural regulators include the central nervous system (CNS) control of resp
rate, depth, and rhythm.
● Chemical regulation involves the influence of carbon dioxide and hydrogen
ions on the rate and depth of inspiration
alterations in respiratory functioning
Illnesses and conditions that affect ventilation or oxygen transport cause
alterations in respiratory functioning.
● The goal of ventilation is to produce a normal arterial carbon dioxide between
35-45 mmHg and a normal arterial oxygen between 80-100 mmHg.
● Three primary alterations are:
○ Hyperventilation
○ Hypoventilation
○ Hypoxia
hyperventilation
Excess ventilation required to eliminate the normal venous carbon dioxide.
* Anxiety, infections, drugs, or an acid-base imbalance can induce hyperventilation.
* RR > 20 breaths/min
hypoventilation
Occurs when alveolar ventilation is inadequate to meet the body’s oxygen demand or
to eliminate sufficient carbon dioxide.
* As ventilation decreases – PaCO2 is elevated.
* Can be caused by atelectasis and inappropriate administration of oxygen in patients
with COPD.
* Atelectasis: the collapse of alveoli that prevents normal respiratory exchange. Less
lung is able to be ventilated and hypoventilation occurs.
* RR < 12 breaths/min
* Signs and symptoms include: change in mental status, dysrhythmias, and potential
cardiac arrest.
hypoxia
nadequate tissue oxygenation at the cellular level.
● Results from a deficiency in oxygen deliver or oxygen utilization.
● Can be caused by:
○ Decreased hemoglobin level
○ Diminished concentration of inspired oxygen
○ Inability of the tissues to extract oxygen from the blood
○ Decreased diffusion of oxygen from the alveoli to the blood
○ Poor tissue perfusion with oxygenated blood
○ Impaired ventilation
● Signs & symptoms include:
○ Restlessness/agitated
○ Decreased level of consciousness
○ Dizziness
○ Tachycardia
○ Increased respiratory rate (early signs)
cyanosis
blue discoloration of the skin and mucous membranes caused by the
presence of desaturated hemoglobin in capillaries. This is a late sign of hypoxia!
○ Central cyanosis: observed in the tongue, soft palate, and conjunctiva of the
eye – indicates hypoxemia.
○ Peripheral cyanosis: seen in the extremities, nail beds, and earlobes – often a
result of vasoconstriction and stagnant blood flow.
