Download Respiratory System Notes

Respiratory System Notes
1. General Information:
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The chief function of the respiratory system is to supply body tissues with
oxygen and eliminate carbon dioxide.
The respiratory system consists of the nasal cavities, pharynx, larynx,
___________________, bronchi, and lungs.
The nasal cavities, pharynx, larynx, trachea, and bronchi constitute the
airway.
2. Nose
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The nose has two nasal cavities, which open on the face through the
anterior nasal apertures called the nares. The nasal septum separates the
cavities.
The anterior portion of the septum is composed of hyaline cartilage. The
posterior portion is composed of bone called the vomer and the
perpendicular plate of the ethmoid bone.
Each nasal cavity has three mucosa-covered structures called the superior,
middle, and inferior conchae.
The nasal cavities are lined with ________ that trap dust and foreign
particles.
Epithelial cells lining the nasal cavities secrete mucus, which collects
foreign particles which are then moved by _________ toward the pharynx,
where the particles and mucus can be removed by swallowing, sneezing,
or spitting.
The paranasal sinuses, which surround and drain into the nasal cavities,
are located in the frontal, sphenoid, and maxillary bones.
3. Pharynx
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The pharynx is also known as the _____________.
Acts as a passageway for air and food. It also functions in speech,
changing shape to allow phonation of vowel sounds.
The entire pharynx is composed of
striated muscle and lined with
___________ membrane.
The pharynx has three divisions…
i. Nasopharynx
ii. Oropharynx
iii. Laryngopharynx
4. Larynx
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The larynx is called the voice box.
It is a triangular organ in the front of the neck. It extends from the 4th to
the 6th cervical vertebrae, attaching to the __________ bone.
The larynx is composed of muscle and numerous cartilages
The true vocal cords are a pair of horizontal folds that project into the
laryngeal cavity. They are separated by a space called the glottis.
The epiglottis, which overhangs the larynx, prevents food from entering
the lungs.
5. Trachea
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The trachea is also called the ________________.
It is a membranous tube measuring 10 to 12.5 cm long.
On entering the mediastinum, the trachea branches into the right and left
main bronchi at the 5th thoracic vertebrae.
Dorsally, the trachea contacts the esophagus.
The trachea has a series of C-shaped _____________ rings to strengthen
the trachea and prevents it from collapsing during inspiration.
The trachea is lined with ciliated pseudostratified columnar epithelium
containing mucus-secreting __________ cells, which trap and propel
inhaled debris upward to the pharynx for removal through coughing.
6. Bronchi
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The ____________ and ____________ primary bronchi branch from the
trachea.
The secondary bronchi are smaller passageways that branch from the
primary bronchi. The right primary bronchi divides into three secondary
bronchi and the left branches into two secondary bronchi.
The secondary bronchi branch into tertiary bronchi which then branch into
smaller bronchioles which branch into progressively smaller tubes until
they branch into alveolar ducts, which terminate in clusters called alveoli.
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_______________ are tiny air sacs lined with thin squamous epithelium.
They are surrounded by capillaries where oxygen and carbon dioxide are
exchanged.
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The lungs are paired, cone-shaped organs that fill the pleural divisions of
the thoracic cavity. They extend from the root of the neck to the
diaphragm.
The right and left lungs are separated by the heart and other mediastinal
structures.
Each lung is enclosed in a ________________, a protective, doublelayered serous membrane. The parietal pleura lines the wall of the
thoracic cavity. The visceral pleura covers the lung directly. The space
between the two membranes contains fluid, which lubricates the lungs as
they expand and contract.
7. Lungs
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8. Lobes
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The right lung is divided into three lobes. The left lung, smaller than the
right, is divided into two lobes. It contains a concavity called the
______________ notch, which is molded to accommodate the heart.
9. Breathing:
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Inspiration occurs when the _____________ contracts, moving downward,
and the intercostal muscles expand the size of the chest cavity. The
increase in the size of the chest cavity reduces pressure within it and air
moves from the outside high pressure to the low pressure inside the lungs.
Expiration occurs when the diaphragm and ____________________
muscles relax and therefore reduce the size of the chest cavity. This
increases air pressure and air moves out. The elastic recoil of lung tissue
aids in expiration.
10. Gas Exchange
 Air exerts a total pressure of 760 mm Hg at sea level …. Here in
Albuquerque is ~640 mm Hg and so partial pressure of oxygen is 134 mm
Hg
 Air contains about ______% oxygen. The partial pressure of oxygen is
21% of the atmospheric pressure 760 mm Hg. So the partial pressure of
oxygen is 159.6 mm Hg.
 Gas concentrations in inspired air…
i. Nitrogen = 79%
ii. Oxygen = 21%
iii. Water vapor = .5%
iv. Carbon dioxide = .04%
 Gas concentrations in alveolar air…
i. Nitrogen = 74.9%
ii. Oxygen = 13.6%
iii. Water vapor = 6.2%
iv. Carbon dioxide = 5.3%
 Gas concentrations in expired air…
i. Nitrogen = 74.9%
ii. Oxygen = 15.7%
iii. Water vapor = 6.2%
iv. Carbon dioxide = 3.6%
11. Gas diffusion
 In diffusion substances move from an area of higher concentration to an
area of ____________ concentration. A gas diffuses from an area with a
high partial pressure of the gas to one with a lower partial pressure.
12. Transport of oxygen
 Oxygen is transported by the blood in two different methods.
i. About 3% of oxygen is dissolved in blood plasma
ii. The remaining 97% is chemically bound with
________________________ (carries 4 oxygens). Oxygen uptake
by hemoglobin is most efficient in the lungs where the oxygen
concentration is high. Oxygen release occurs most readily in the
tissues where the oxygen concentration is low.
iii. Lower blood pH and higher temperatures of actively metabolizing
tissue, which occurs during vigorous exercise, also enhances
oxygen release from hemoglobin.
13. Transport of carbon dioxide
 Carbon dioxide is transported by three different methods.
i. A small amount is dissolved in the blood plasma
ii. Some is loosely combined with amino groups in the hemoglobin
molecule.
iii. Most of the carbon dioxide is converted in erythrocytes to
____________________ by the enzyme carbonic anhydrase.
Erythrocyte uptake of carbon dioxide begins in the capillaries.
1. In the erythrocyte, the hemoglobin releases oxygen to
supply the tissues. At the same time, carbon dioxide
diffuses from the tissues into the erythrocytes where
enzymes help turn carbon dioxide and water into carbonic
acid. H2O + CO2  H2CO3.
2. Then carbonic acid dissociates into hydrogen ions (H+) and
bicarbonate ions (HCO3 -). The hemoglobin molecules
take up the hydrogen ions. The remaining bicarbonate ions
accumulate until their concentration in the erythrocyte
exceed that in the plasma, then the excess will diffuse out
into the plasma.
3. Simultaneously, chloride ions diffuse into the erythrocyte
to replace the bicarbonate ions. Then the bicarbonate ions
combine with plasma sodium and form sodium bicarbonate.
4. At the lungs the whole process reverses and carbon dioxide
diffuses into the alveoli and is exhaled.
16. Control of Respiration
 A control center in the brain stem, called the respiratory center, regulates
the rate and depth of respiration.
 This center discharges impulses to neurons that innervate the diaphragm
and intercostal muscles.
 Neurons in the respiratory center are stimulated directly by increased
arterial concentrations of carbon dioxide and hydrogen ions.
 During exercise, more carbon dioxide is produced. This stimulates the
respiratory center to increase respiratory rate and depth.
 Chemoreceptors in the _____________________ and carotid sinus detect
levels of carbon dioxide and convey impulses to the respiratory center.
 Receptors in the lungs respond to stretching as the lungs inflate, sending
impulses to the respiratory center to inhibit further inspiration.
 The cerebral cortex sends impulses to the respiratory center in response to
strong emotions, such as anxiety, fear, and anger.
 Some sensory stimuli, such as irritating vapors may cause reflex inhibition
of respiration.