Respiratory System

Question 1

Basic functions of the

respiratory system

Answer 1

Absorbs oxygen from air into blood
•  Disposes of carbon dioxide into air from
blood

Question 2

Respiratory organs

Answer 2

•   Nose, nasal cavity, and paranasal sinuses
•   Pharynx, larynx, and trachea
•   Bronchi and bronchioles (smaller branches)
•   Lungs and alveoli

Question 3

Conduction & respiratory zones

Answer 3

Conducting zone: carries air to sites 
of gas exchange and filters, humidifies, 
and warms air as it is conducted 
through nose, mouth, throat, trachea 
and bronchi 
•  Respiratory zone: actual site of gas 
exchange in the lungs in bronchioles, 
alveolar ducts, and alveolar sacs

Question 4

The Nose (function)

Answer 4

Provides an airway for respiration 
•  Moistens and warms air 
•  Filters inhaled air 
•  Resonating chamber for speech 
•  Houses olfactory receptors

Question 5

The Nose (Composition)

Answer 5

•  Size variation due to differences in nasal hyaline cartilage
(septal cartilages & alar cartilages)
•  Lateral border of nostril composed of dense fibrous
connective tissue
•  Skin is thin—contains many sebaceous glands

Question 6

The Nasal Cavity

Answer 6

•  External nares—nostrils 
•  Divided by nasal septum 
•  Continuous with nasopharynx through 
choanae (posterior tunnel shaped nasal 
apertures)

Question 7

Nasal Cavity

Olfactory Mucosa

Answer 7

•   Near roof of nasal cavity

*   Houses olfactory (smell) receptors

Question 8

CN 1, Olfactory Nerve

Answer 8

CN I is sensory nerve of smell which runs through
cribiform plate of ethmoid bone
•  Olfactory mucosa is near roof of nasal cavity

Question 9

Nasal Respiratory mucosa

Answer 9

•  Lines nasal cavity
•  Epithelium is pseudostratified ciliated
columnar which moves mucous
•  Goblet cells within epithlium
•  Underlying layer of lamina propria (areolar
connective tissue) is richly supplied with
tubuloalveolar glands that contain both
mucous cells which produce sticky mucus
and serous cells that produce watery fluid
which contains digestive enzymes

Question 10

Nasal Respiratory mucosa

Answer 10

•  The sticky mucus covers the mucosal surface and
traps the inhaled bacteria, viruses, pollen, dust, &
other debris
•  Each day, the nasal glands and the epithelial goblet
cells secrete about a liter of mucus which contains
a lysozyme enzyme that destroys and digests
bacteria and viruses
•  The ciliated cells in the pseudostratified ciliated
columnar epithelial lining create a gentle current
that moves the mucus posteriorly to the pharynx
where it is swallowed and mixed with the digestive
enzymes in the stomach

Question 11

Nasal Conchae (= turbinates)

Answer 11

•  Superior and middle nasal conchae
– Part of the ethmoid bone
•  Inferior nasal conchae
– Separate bone

Question 12

Nasal conchae

Answer 12

•  As inhaled air rushes over the curved
conchae, the resulting turbulence greatly
increases the amount of contact between
the nasal mucosa and the inhaled air
•  This causes the air’s particulate matter to be
deflected onto the mucus-coated surfaces
•  The conchae and nasal mucosa function
during inhalation to filter, heat, and moisten
the air

Question 13

Paranasal sinuses: cavities in

cranial bones near the nose

Answer 13

Lined with mucosa and are typically filled
with air
•  Extensions of the nasal cavity
•  Connect to the nasal cavity through the
meatuses inferior to the conchae
•  Help to humidify, warm, and filter inhaled air
•  Lighten skull
•  Sinusitis can develop when they become
infected and full of fluid

Question 14

Paranasal sinuses: cavities in

cranial bones near the nose

Answer 14

Maxillary sinuses under the eyes in the
maxillary bones
•  Frontal sinuses, superior to the eyes, in the
frontal bone
•  Ethmoid sinuses in the ethmoid bone
•  Sphenoid sinuses in the sphenoid bone at
the center of the skull base

Question 15

The Pharynx

Answer 15

  Funnel-shaped passageway 
•  Connects nasal cavity and mouth 
•  Divided into three sections by location 
– Nasopharynx 
– Oropharynx 
– Laryngopharynx 
•  Type of mucosal lining changes along 
its length

Question 16

The Nasopharynx

Answer 16

•  Superior to the point where food enters
•  Conducts air
•  Ciliated pseudostratified columnar epithelium propels
mucus
•  During swallowing the soft palate and its uvula reflect
superiorly and closes off nasopharynx
•  Contains the opening to the pharyngotympanic tube
(auditory or eustachean tube)
•  Tubal tonsil is posterior to pharyngotympanic tube and
provides some protection from infection
•  Pharyngeal tonsil (adenoids)
– Located on posterior wall of nasopharynx
– Defends against pathogens entering in air and on foods

Question 17

The Oropharynx

Answer 17

Arch-like entranceway—fauces
•  Extends from soft palate to the epiglottis
•  Stratified squamous epithelium
•  Both food and air pass through oropharynx
•  Two types of tonsils in the oropharynx
– Palatine tonsils—in the lateral walls of
the fauces
– Lingual tonsils—covers the posterior
surface of the tongue

Question 18

The Laryngopharynx

Answer 18

•  Passageway for both food and air
•  Stratified squamous epithelium
•  Continuous with the esophagus and
larynx

Question 19

Larynx functions

Answer 19

•  Voice production 
•  Provides an open airway 
•  Routes air and food into the proper 
channels 
• Epiglottis 
–  closed during swallowing 
–  open during breathing

Question 20

Larynx

Answer 20

•  Positioned at level C4-C6 
•  Superiorly attached to hyoid bone 
•  Inferiorly attached to trachea 
•  Superior part of larynx has stratified 
squamous epithelium 
•  Inferior to vocal cord the epithelium is 
pseudostratified ciliated columnar with 
upward directed power stroke of cilia 
which helps clear dust trapping mucus

Question 21

Nine Cartilages of the Larynx

Answer 21

•  Epiglottis: Tips inferiorly to cover entry into
trachea during swallowing
•  Thyroid cartilage: shield-shaped, forms
laryngeal prominence (Adam’s apple)
•  Three pairs of small cartilages
– Cuneiform cartilages
– Corniculate cartilages
– Arytenoid cartilages
•  Cricoid cartilage: the only laryngeal
cartilage that forms a complete ring

Question 22

The Larynx 2

Answer 22

•  Innervation of the larynx by recurrent 
laryngeal nerves (branch of vagus nerve/
CN X) 
•  Ligaments of the larynx 
– Vocal folds (true vocal cords) 
• Act in voice production 
– Vestibular folds (false vocal cords) 
• No role in voice production

Question 23

Larynx size

male versus female

Answer 23

  The thyroid cartilage is larger in adult
men than adult women because male
sex hormones stimulate its growth
during puberty
•  Adult males have longer vocal folds and
deeper voices than than adult females

Question 24

Trachea

Answer 24

•  Descends into the mediastinum
•  C-shaped cartilage rings keep airway open
•  Pseudostratified ciliated columnar epithelium
•  Carina marks where trachea divides into two
primary bronchi

Question 25

Supportive connective tissue in | walls trachea and lung tubes

Answer 25

Trachea: hyaline cartilage rings •  As main bronchi enter lungs: cartilage rings are replaced with irregular plates of cartilage •  Bronchi: plates of cartilage •  Bronchioles: elastin

Question 26

Lung landmarks

Answer 26

•  Apex: superior tip of lung •  Base: inferior surface of lung which sets on the diaphram •  Hilum: indentation on medial surface of each lung through which bronchi, blood vessels, lymph vessels, and nerves enter and exit the lung •  Left lung: Superior & inferior lobes • Fissure—oblique •  Right lung: Superior, middle, & inferior lobes • Fissures—oblique and horizontal

Question 27

Bronchi & Bronchioles in Conducting Zone

Answer 27

``` •  Primary (main) bronchi: right and left with right main bronchi wider and shorter than the left main bronchi •  Secondary (lobar) bronchi – Three on the right – Two on the left •  Tertiary (segmental) bronchi – Branch into each lung segment •  Bronchioles – Less than 1 mm in diameter •  Terminal bronchioles – Less than 0.5 mm in diameter ```

Question 28

Bronchopulmonary segments

Answer 28

``` Right lung •  Right superior lobe: 3 segments •  Right middle lobe: 2 segments •  Right inferior lobe: 5 segments Left lung •  Left superior lobe: 4 segments •  Left inferior lobe: 5 segments ```

Question 29

Epithelial Changes along Pathways in | Lungs

Answer 29

pseudostratified ciliated columnar which produce mucus (trachea & bronchi) •  simple columnar with cilia which produce mucus (large bronchioles) •  simple cuboidal (terminal and respiratory bronchioles; Type II alveolar cells) •  simple squamous epithelium (Type I alveolar cells)

Question 30

Smooth muscle composition in | smaller bronchi and bronchioles

Answer 30

Smooth muscle influences diameter of smaller bronchi and bronchioles – Airways dilate with sympathetic stimulation – Airways constrict with parasympathetic stimulation

Question 31

Air-exchanging structures of Respiratory Zone:

Answer 31

- Terminal bronchioles - Respiratory bronchioles - Alveolar ducts - Alveolar sacs - Alveoli

Question 32

Structures of the Respiratory Zone

Answer 32

- Respiratory bronchiole -   Alveolar duct -   Alveolar sac - Alveoli - Alveolar pores

Question 33

Alveoli number and surface area

Answer 33

•  300 million alveoli account for tremendous surface area of the lungs •  Surface area of alveoli is 140 square meters

Question 34

Alveoli structure

Answer 34

The wall of each alveolus consists of a single layer of simple squamous epithelial cells, called Type I cells—which are surrounded by a delicate basal lamina •  Alveolar macrophages move freely along the inner surfaces of alveoli and engulf microbes •  Alveolar pores interconnect alveoli and equalize air pressure throughout the lung •  Basal lamina of alveolar epithelium and blood capillary endothelium are fused to form the respiratory membrane through which O2 and CO2 are exchanged

Question 35

Type II cells in alveoli

Answer 35

•  Type II cells are scattered among type I cells •  Type II are cuboidal epithelial cells •  Secrete surfactant which reduces surface tension within alveoli to keep them inflated

Question 36

Blood Supply & Innervation of Lungs

Answer 36

``` Pulmonary arteries – Deliver oxygen-poor blood to the lungs •  Pulmonary veins – Carry oxygenated blood to the heart •  Innervation of lungs – Parasympathetic—constrict bronchial airways – Sympathetic—dilate bronchial airways – Visceral sensory ```

Question 37

The Pleurae

Answer 37

``` A double-layered sac surrounding each lung – Parietal pleura – Visceral pleura •  Pleural cavity – Potential space between the visceral and parietal pleurae •  Pleurae help divide the thoracic cavity – Central mediastinum – Two lateral pleural compartments ```

Question 38

Neural Control of Ventilation

Answer 38

•  Most important respiratory center, called the ventral respiratory group (VRG) is in reticular formation in the medulla oblongata •  VRG is a pacemaker which generates respiratory rhythm and rate with input from the pons respiratory centers and dorsal respiratory group (DRG) in dorsal medulla oblongata

Question 39

Neural Control of Ventilation

Answer 39

Medulla respiratory center is influenced by input from chemoreceptors that sense the chemistry of blood •  Chemoreceptors – Sensitive to rising and falling O2 and CO2 levels – Central chemoreceptors—located in medulla oblongata – Peripheral chemoreceptors transmission of sensory information • Aortic bodies via vagus nerve • Carotid bodies via glossopharyngeal nerve and possibly also vagus nerve

Question 40

Two phases of | pulmonary ventilation

Answer 40

*   Inspiration—inhalation | *   Expiration—exhalation

Question 41

Inspiration

Answer 41

  Volume of thoracic cavity increases •  Diaphragm flattens and moves inferiorly •  Contraction of external intercostal muscles raises the ribs upward •  During quiet inspiration, the external and internal intercostal muscles function together to stiffen the thoracic wall

Question 42

Quiet Expiration

Answer 42

*   Quiet expiration—chiefly a passive process *   Inspiratory muscles relax *   Diaphragm moves superiorly *   Volume of thoracic cavity decreases

Question 43

Muscles which contribute to | deep inspiration

Answer 43

*   Scalenes *   Sternocleidomastoid *   Pectoralis minor *   Erector spinae

Question 44

Forced Expiration is an active | process produced by contraction of

Answer 44

*   Internal and external oblique muscles *   Transverse abdominis muscles *   Latissimus dorsi *   Internal intercostals

Question 45

Disorders of | Lower Respiratory Structures

Answer 45

``` Bronchial asthma: constriction of bronchiole smooth muscle which results in difficulty inhaling air •  Emphysema: breaking down of alveolar walls and loss of lung elasticity which results in air trapping ```