Download I. Types of respiration

RESPIRATORY SYSTEM
I.
TYPES OF RESPIRATION
A. Pulmonary ventilation (breathing)
1. Entrance and exit of air into and from the lungs
B. External respiration
1. Exchange of O2 and CO2 between the air and blood
C. Internal respiration
1. Exchange of O2 and CO2 between blood and tissue fluid
D. Cellular respiration
1. Production of ATP by mitochondria
2. C6H12O6 + 6 O2  6 H2O + 6 CO2 + 38 ATP
II. PLEURAL MEMBRANES
A. Visceral pleural
1. Encloses the lungs
B. Parietal pleural
1. Lines the chest walls and diaphragm
C. Membranes adhere to each other
1. Reduced pressure and thin film of fluid between the two
2. When parietal pleural moves, the visceral pleural will move with it
III. ANATOMY OF THE RESPIRATORY TRACT
A. The Nose
1. Contains 2 nasal cavities
a) Large hollow spaces behind the nose
b) Separated by a median septum
2. Contains receptors for smell
3. Mucous membranes radiate heat to warm air and water to moisturize it
4. It is sticky to entrap dust and other small particles, such as bacteria
a) This mucous slides to the pharynx and is swallowed
b) Microorganisms trapped in the mucous are usually destroyed by the gastric
juices
5. Sinuses
a) Air-filled spaces in the skull that open into the nasal cavity and are lined with
mucous membranes
(1) Mucous is drained into nasal cavity; if blocked by inflamed membrane, fluid
accumulates and causes pressure leading to headache
b) Sinuses function to reduce skull weight and affect voice quality
B. The Pharynx
1. Common passageway for both air and food
a) Connected to the mouth, esophagus, nasal cavity, and larynx
b) The nasopharyngeal opening closes when the soft palate moves back during
swallowing
c) The opening to the trachea (the glottis) closes when the epiglottis folds over
it
2. Trachea lies in front of the esophagus
C. The Larynx
1. Called the voice box because it contains the vocal cords at the sides of the
glottis
a) An opening covered by the epiglottis during swallowing of food
2. Food lodged in the larynx may be removed by the Heimlich maneuver
a) A more drastic procedure is an incision is made to allow air in and out -termed a tracheotomy
D. The Trachea
1. Held open by C-shaped cartilaginous rings
2. Leads to the lungs
E. Lungs
1. Right lung has 3 lobes and the left lung has 2 lobes
2. Consists of bronchi, bronchioles, and alveoli
3. Bronchi
a) Air enters the right and left lungs via the 2 bronchi which branch into smaller
units termed bronchioles
4. Bronchioles
a) Terminate into air pockets termed alveoli
b) Cartilage is lost and smooth muscle becomes more common as bronchial
tree divides and the walls become thinner
5. Alveoli
a) Dead end air sacs
b) Approximately 300 million alveoli
(1) Increased surface area for gas exchange
c) Gas exchange occurs in the alveoli through a single layer of squamous
epithelium surrounded by blood capillaries
IV. THE MECHANISM OF BREATHING
A. Introduction
1. Inspiration
a) Inhalation
b) Taking air into the respiratory system
c) Active process
(1) Requires muscle contraction and energy expenditure
2. Expiration
a) Exhalation
b) Forcing air out of the respiratory system
c) Expired air has less oxygen but more carbon dioxide than inspired
d) Passive
(1) Lungs recoil
(2) Requires no energy expenditure or muscle contractions
B. Stimulation of inspiration
1. Medulla oblongata
a) Contains the respiratory center
b) Measures pH of blood
(1) CO2 reacts with water to form carbonic acid
(2) Therefore, decreased pH is indicative of the need to increase respiration
c) Medulla oblongata will stimulate two motor nerves
(1) Phrenic nerve
(a) Causes contraction of the diaphragm
(2) Intercostal nerve
(a) Causes contraction of rib cage intercostal muscles
C. Mechanism of inspiration
1. Contraction of the diaphragm and rib cage intercostal muscles increases the
volume of the thoracic cavity
a) This reduces alveolar pressure
b) Now, due to the greater atmospheric pressure outside, air rushes in
c) Therefore, humans breathe by negative pressure
(1) Creation of a partial vacuum sucks air into the lungs
D. Expiration
1. Stimulation and mechanism
a) Stretch receptors
(1) Receptors in lungs send inhibitory message via the vagus nerve to the medulla
oblongata
b) This inhibits the phrenic and intercostal nerves
(1) Diaphragm and rib cage intercostal muscles relax
(2) Diaphragm returns to its original dome shape
(3) Rib cage moves down and inward
c) Lungs recoil due to elastic tissue within it
(1) Expiration is a passive process since muscle contraction is not normally
needed
V. EXTERNAL AND INTERNAL RESPIRATION
A. External Respiration
1. Refers to the exchange of gases between the air in the alveoli and the blood
within the pulmonary capillaries
a) Since the alveolus and the capillary are composed of a single layer of cells,
diffusion alone accounts for gas exchange
b) Carbon dioxide diffuses out because there is a greater concentration of it in
the lung capillaries than in the alveolar air
c) Oxygen diffuses in because there is a higher concentration of it in the
alveolus than in the capillary
B. Internal Respiration
1. Refers to the exchange of gases between the blood in the systemic capillaries
and the surrounding tissue fluid
a) During cellular respiration, oxygen is being used up in the cells while
releasing carbon dioxide
(1) Thus, oxygen diffuses out of the blood into the tissue fluid because the oxygen
concentration there is low
b) Conversely, carbon dioxide is in high amounts at the tissue fluid (being
released from the cells) and diffuses into the capillaries
VI. RESPIRATORY SYSTEMS
A. Cutaneous respiration
1. Gas exchange occurs by the process of diffusion
a) This surface area must be moist, thin, and large
2. Many small animals (jellyfishes, flatworms, some salamanders) use the body
surface for gas diffusion
B. Gills
1. Highly vascularized outgrowths of the body surface
C. Tracheal system
1. Found in insects
a) The circulatory system plays no role in respiration
2. Spiracles
a) Openings in the body surface through which air enters
3. Trachea
a) Tubes from the spiracles that branch into smaller vessels that spread
through internal tissues
D. Lungs
1. Found in terrestrial vertebrates
2. Vascular outgrowth of the pharyngeal region in the chest cavity