Chapter 13 in the Books
I. Respiratory System
- Organs include the nose, pharynx, larynx, trachea, bronchi, alveoli and lungs.
- Primary structure consists of a tube ending in millions of air sacs called alveoli (resembles upside down grape vine)
- Diffusion allows for exchange of gases in alveoli between alveoli and capillaries.
II. Respiratory System
- Air distribution and gas exchange (between capillaries and lungs & between capillaries and body cells)
- Provides oxygen and removes carbon dioxide.
- Also filters, warms, and humidifies air.
III. Respiratory Tract
a. Upper Tract
i. Organs located outside thorax (Nose, pharynx, larynx)
ii. Upper respiratory infection – Head Cold, Sinusitis, Tonsillitis, Strept Throat
b. Lower Tract
i. Organs within thorax (Trachea, bronchial tree, and lungs)
1. Lower respiratory infection – Pneumonia, Bronchitis, Asthma, Emphysema, Lung cancer
IV. Respiratory Mucosa
a. Membrane that lines the air distribution tubes.
b. Covered with mucus which purifies air by removing irritants (dust, pollen, bacteria).
c. 125 ml created daily and distributed by cilia.
a. Air enters through external nares (nostrils)
b. Flows into either left or right nasal cavity which are separated by nasal septum.
c. Nasal cavities kept moist from mucus and warm from blood flow.
d. 4 Paranasal sinuses
i. frontal, maxillary, sphenoidal, and ethmoidal
ii. drain into nasal cavities and can become infected (sinusitis)
e. 3 Nasal Conchae protrude on each side of nasal cavity to increase surface area.
a. Commonly referred to as the throat
b. Divided into 3 portions
i. Nasopharynx – Upper part behind nasal cavity
ii. Oropharynx – Portion behind oral cavity
iii. Laryngopharynx – Lowest portion
c. Passageway for food and air
d. Air enters through pharynx and leaves through larynx
e. Food enters from mouth and leaves by esophagus
f. Eustachian tube enters into nasopharynx and equalizes air pressure
g. Tonsils embedded in pharynx
i. Pharyngeal and adenoids in nasopharynx
ii. Palatine in oropharynx
a. Voice box
b. Located below pharynx
c. Composed of several pieces of cartilage
i. largest is thyroid cartilage – Adam’s Apple
d. 2 fibrous bands (vocal cords) stretch across larynx
i. Muscles pull on or relax cords
1. Tense – Voice is high
2. Relaxed – Voice is low
e. Space between cord is glottis
f. Epiglottis – Flaplike structure which opens to allow air in and closes to keep food out of trachea
VIII. Vocal Cords (Picture)
b. Provides passageway for air to reach lungs
c. Made up of rings of cartilage so that it does not collapse.
X. Bronchi, Bronchioles, and Alveoli
a. Bronchi – Main branches composed of primary and secondary branches
b. Bronchioles – Branches of bronchi
c. Alveolar ducts – Tubes which branch off bronchioles ending in alveolar sacs
d. Alveoli – Thin walled sacs which are site of gas exchange
XI. Lungs and Pleura
a. Lungs – Right has 3 lobes, Left has 2
b. Pleura – Cover outer surface of lungs and lines inner surface of rib cage.
i. Parietal Pleura – Lines wall of thoracic cavity.
ii. Visceral Pleura – Covers the lung
iii. Interpleural space – Space between two pleural membranes.
c. Pneumothorax – Presence of air in interpleural space which adds pressure on the lung and causes it to collapse.
a. Exchange of gases between a living organism and its environment
b. Pulmonary ventilation – Process that moves air into and out of lungs.
c. External Respiration – Exchange of gases between air and lungs.
d. Internal Respiration – Exchange of gases between blood and cells.
XIII. Mechanisms of Breathing
a. Inspiration – Movement of air into lungs.
i. Occurs when chest cavity enlarges.
ii. Inspiratory muscles help draw air in (diaphragm and external intercostals).
iii. Diaphragm – Dome shaped muscle separating abdominal from thoracic cavity.
iv. Contracts (moves down) making chest cavity larger to allow air in.
v. Phrenic nerve stimulates contraction.
vi. External Intercostals – Located between ribs increasing thorax size from back to front and side to side.
i. Occurs when inspiratory muscles relax and expiratory muscles contract (internal intercostals and abdominal muscles)
ii. Thorax size decreases (depresses rib cage)
iii. Diaphragm elevates during relaxation and forces air out of lungs.
XIV. Lungs of the Cat
a. Differences with cats and humans
i. Cats have 4 lobes of the right lung, only three lobes in humans
ii. Cats have 3 lobes of the left lung while humans only have 2
1. Less lobes on the left side due to the placement of the heart in the thorax (slightly off center and to the left).
XV. Exchange of Gases in Lungs
a. Accomplished by diffusion
i. Oxygen combines with hemoglobin to form oxyhemoglobin
ii. Carbon dioxide, carried as bicarbonate, combines with hemoglobin to form carbaminohemoglobin
XVI. Exchange of Gases in Tissues
a. Oxyhemoglobin is broken down to oxygen and hemoglobin in capillaries giving tissues needed oxygen.
XVII. Regulation of Respiration
a. Normal respiration depends on proper functioning of muscles of respiration
b. Respiratory control centers (Pons and Medulla) stimulate muscles through nervous impulses
c. Nervous system influenced by “receptors”
i. Cerebral cortex – Voluntary control
ii. Chemoreceptors – Respond to changes in CO2, O2 and blood acid levels (carotid arteries and aorta)
iii. Pulmonary stretch receptors – Respond to stretch in lungs (protection from overinflation)
XVIII. Types of Breathing
a. Eupnea – Normal Breathing
b. Hyperventilation – Rapid and deep breathing
c. Hypoventilation – Slow and shallow breathing
d. Dyspnea – Labored breathing
e. Apnea – Stopped respiration
f. Respiratory Arrest – Failure to breathe following apnea
XIX. Volumes of Air Exchange in Pulmonary Ventilation
a. Spirometer – Instrument used to measure amount of air exchange
b. Tidal Volume – Amount of air in normal exhale (500 ml=1 pint) each breath
c. Inspiratory Reserve Volume – Amount of air that can be forcibly inhaled after normal inspiration.
d. Expiratory Reserve Volume – Amount of air that can be forcibly exhaled after expiring tidal volume.
e. Vital Capacity- Total amount of exchangeable air (4800 ml)
i. VC= TV+IRV+ERV
f. Residual Volume – Air that remains in lungs after most forceful expiration needed to keep alveoli open
XX. Respiratory Diseases/Problems
d. Dyspnea “short of breath (SOB)” is perceived difficulty breathing or pain on breathing. It is a common symptom of numerous medical disorders.
e. Asthma is a chronic disease of the respiratory system in which the airway occasionally constricts, becomes inflamed, and is lined with excessive amounts of mucus, often in response to one or more triggers.
i. Viral illnesses; Allergic reactions to dust and/or pollen
i. most often due to tobacco smoking
g. Eupnea is normal, unlabored ventilation
h. Hypoxia literally means "deficient in oxygen."
i. High altitudes, low blood levels, low oxygen levels
i. prolonged cough of more than three weeks duration, chest pain and coughing up blood