Anatomy & Physiology I: Chapter 23 Notes
I.
3 Major Respiration Processes
A.
Pulmonary ventilation - inspiration and expiration; uses breathing muscles; exchange of
O2 and CO2
B.
External respiration - exchange of gases between air sacs in the lungs (alveoli) and blood
in the pulmonary capillaries; pulmonary capillary blood gains O2 and loses CO2
C.
Internal respiration - exchange of gases between blood in systemic capillaries and tissue
cells; blood looses O2 and gains CO2
II.
Anatomy of the Respiratory System
A.
Nose - warm, moisten, and filter incoming air; detect olfactory stimuli; modify speech
vibrations as they pass through resonating chambers
B.
Pharynx - functions as a passageway for air and food; provides a resonating chamber for
speech sounds; houses the tonsils
i.
Tonsils - two pairs (palatine and lingual) are found in the oropharynx; pharyngeal
tonsil is located in the posterior wall
C.
Larynx(voice box) - short passage way that connects the laryngopharynx with the trachea
i.
Thyroid cartilage(adam's apple) - consists of two fused plates of hyaline cartilage
that from the anterior walls of the larynx
ii.
Thyroid gland - H shaped and regulates metabolism
iii.
Parathyroid gland - each person usually has four; located behind the thyroid gland;
regulates Ca2 metabolism
iv.
Cricoid cartilage - ring of hyaline cartilage that forms the inferior wall of the
larynx; landmark for making an emergency airway
v.
Tracheal cartilage - behind the esophagus
D.
Trachea(windpipe) - tubular passageway for air; anterior to the esophagus
i.
Right and left primary bronchus - located around fifth thoracic vertebrae; where
trachea divides
ii.
Secondary bronchi - branch for each lobe of the lung (three on right; two on left);
branch from right and left primary bronchus
iii.
Tertiary bronchi - branches of the secondary bronchi that branch into bronchioles
iv.
Bronchioles - branch repeatedly into the smallest branches called terminal
bronchioles
v.
Terminal bronchioles - the smallest branches
vi.
Respiratory bronchiole - distal to the terminal bronchioles (further from center of
body)
vii.
Alveolar ducts - distal to respiratory bronchioles
E.
Lungs
i.
Two layers of pleural membrane
a.
Parietal pleura - superficial; lines the wall of the thoracic cavity
b.
Visceral pleura - deep; covers the lungs themselves
c.
Pleural cavity - between the two membrane layers; contains lubricating
fluid to prevent friction
ii.
Right lung has 3 lobes and is thicker, shorter, and wider; left lung only has two
lobes
F.
Alveoli
A.
Alveolar sac - two or more alveoli that share a common openening
B.
Alveolar macrophages(dust cells) - phagocytes that remove fine dust particles and
other debris from alveolar spaces; located inside air sacs
C.
G.
H.
III.
Septal cell(type II alveolar cells) - have free surfaces that contain microvilli and
secrete alveolar fluid (includes phospholipids material called surfactant) which
keeps the surface between the cells and the air moist; embedded in air sac wall;
i.
Surfactant lowers the surface tension of alveolar fluid, which reduces the
tendency of alveoli to collapse
D.
Alveolar wall(respiratory membrane)- composed of a epithelial basement
membrane and a capillary basement membrane; allow easy diffusion of O2 and
CO2
Epiglottus - covers the trachea and directs food into the esophagus
The respiratory membrane consists of type I alveolar cells, type II alveolar cells, capillary
endothelium and an epithelial basement membrane
Breathing
A.
Costal breathing - consists of an upward and outward movement of the chest due to
contraction of the external intercostals muscles; shallow
B.
Diaphragmatic breathing - consists of the outward movement of the abdomen due to the
contraction and descent of the diaphragm
i.
Inhalation - air is forced into the lungs which causes the lungs to expand; involves
contraction of the diaphragm and external intercostals; chest volume and vertical
size of the thoracic cavity increase
ii.
Exhalation - results from the elastic recoil of the chest wall and lungs; chest
volume and vertical size of the thoracic cavity decrease; air passes out of the lungs
C.
Breathing is controlled by the medulla oblongata
D.
Boyles law - inverse relationship between volume and pressure
i.
Differences in pressure caused by changes in lung volume force air into our lungs
when we inhale and out when we exhale
ii.
Deep breathing requires the use of many muscles: internal intercostals, external
intercostals (between ribs), abdominal muscles, sternocleinomastoid and scalenes
iii.
Normal exhalation is passive, but exhalation can be active
E.
3 factors affecting pulmonary ventilation
i.
Surface tension of the alveolar fluid - force exerted by the thin layer of alveolar
fluid that coats the luminal surface of alveoli; surfactant reduces surface tension;
respiratory distress syndrome (RDS) is a breathing disorder in which alveoli do
not remain open due to a lack of surfactant
ii.
Compliance of the lungs - how much effort is required to stretch the lungs and
chest wall; depends on flexibility of the elastic tissue around the lobules and
flexibility of the air sacs as well as the amount of surfactant
iii.
Airway resistance - the more resistance the greater the pressure is needed to force
air through passageways; example is asthma; more prevalent in bronchi and
bronchioles
F.
Modified respiratory movements
i.
Coughing - long-drawn and deep inhalation followed by a complete closure of the
rimi glottidis, which results in a strong exhalation that suddenly pushes the rima
glottides open and sends a blast of air through the upper respiratory passages
ii.
Sneezing - spasmodic contraction of muscles of exhalation that forcefully expel
air through the nose and mouth; caused by irritation of the nasal mucosa
iii.
Yawning - deep inhalation through the widely opened mouth producing an
exaggerated depression of the mandible; precise cause is unknown
iv.
Hiccup - spasmodic contraction of the diaphragm followed by a spasmodic closure
of the rima glottides, which produces a sharp sound on inhalation; stimulated by
irritation of the sensory nerve endings of the gastrointestinal tract
IV.
Respiratory Center
A.
Respiratory center - widely dispersed group of neurons which send nerve impulses to
respiratory muscles; composed of the medullary rhythmicity center; apneustic center, and
pneumotaxic center
B.
Three areas
i.
Medullary rhythmicity area - controls the basic rhythm of respiration; nerve
impulses are generated from the inspiratory area that control respiratory muscle
contractions; located in the medulla oblongata
ii.
Pneumotaxic area - shorten the duration of inhalation; located in the pons
iii.
Apneustic area - lengthens the duration of inhalation; located in the pons
C.
Normal breathing rate is 14-15 times per minute
V.
Aging
A.
With age, airways and tissues of the respiratory tract become less elastic and more rigid;
results in a decrease in lung capacity, vital capacity and activity of alveolar macrophages
VII.
Spirogram
A.
Spirogram - record of the volume of air exchanged during breathing and the respiratory
(breathing) rate recorded by a spirometer or respirometer
B.
Tidal volume - volume of one breath; average of 500 ml of air
C.
Inspiratory reserve volume - additional inhaled air over the normal 500 ml during deep
breathing
D.
Expiratory reserve volume - additional exhaled air over the normal 500 ml during deep
breathing
E.
Residual volume - air that remains in the lungs after expiration
F.
Total lung capacity is an average of 6000ml
VIII.
Pressure / Concentration of O2 and CO2
A.
Alveolar sacs have a higher O2 level - give oxygen to capillaries
B.
Capillaries around the alveoli have a higher CO2 level - give carbon dioxide to air sacs
C.
Tissue cells have a higher CO2 level than capillaries - give carbon dioxide to capillaries
D.
Tissue capillaries have a higher O2 level - give oxygen to cells
E.
Oxygen is breathed into the lungs to the alveoli and is then given to the capillaries who in
turn provide the oxygen to tissue cells
IX.
Transportation of O2 and CO2
A.
Oxygen transporation
i.
Hemoglobin (heme portion) binds to oxygen and forms oxyhemoglobin
ii.
Free in plasma
B.
Carbon dioxide transportation
i.
Carbon dioxide is combined with water to create carbonic acid which then
separates into hydrogen and bicarbonate ions
ii.
Free in plasma