Transcript Ch.-23-Lecture-Part-1-wo

Chapter 23:
The Respiratory System
Primary sources for figures and content:
Marieb, E. N. Human Anatomy & Physiology. 6th ed. San Francisco: Pearson Benjamin Cummings, 2004.
Martini, F. H. Fundamentals of Anatomy & Physiology. 6th ed. San Francisco: Pearson Benjamin Cummings,
2004.
The
primary functions of
the respiratory system.
The Respiratory System
• Cells produce energy:
– for maintenance, growth, defense, and
division
– through mechanisms that use oxygen and
produce carbon dioxide
Oxygen
• Is obtained from the air by diffusion
across delicate exchange surfaces of
lungs
• Is carried to cells by the cardiovascular
system which also returns carbon
dioxide to the lungs
5 Functions of the Respiratory System
1. External respiration:
- Provides extensive gas exchange surface area
between air and circulating blood
2. Pulmonary ventilations
- Moves air to and from exchange surfaces of lungs
3. Protects respiratory surfaces from outside
environment
- dehydration, temperature changes, invasion by
pathogens
4. Produces sounds for communication
5. Provide olfactory sensation = Smell
Components of the
Respiratory System
Figure 23–1
Organization of the
Respiratory System
• The respiratory system is divided into
the upper respiratory system, above
the larynx, and the lower respiratory
system, from the larynx down
Anatomy of Respiratory System
1. Upper Respiratory System
– Function to warm and humidify air
– Nose, nasal cavity, sinuses, pharynx
2. Lower Respiratory System
A. Conduction portion
- Bring air to respiratory surfaces
- Larynx, trachea, bronchi, bronchioles
B. Respiratory portion
- Gas exchange
- Alveoli
Alveoli
• Are air-filled pockets within the lungs
– where all gas exchange takes place
The Respiratory Epithelium
Figure 23–2
Respiratory Mucosa = mucus membrane
• Lines conducting portion of respiratory system
• Epithelial layer:
• pseudostratified columnar epithelium
• Usually ciliated
• Scattered goblet cells = mucin production
• Areolar layer = lamina propria (trachea, bronchi)
• Areolar connective tissue
• Mucus glands = mucin
• Serous glands = lysozyme
• Glands produce ~1 quart mucus fluid/day
• Cilia move mucus to pharynx to be swallowed
– Cilia beat slow in the cold
Alveolar Epithelium
• Is a very delicate, simple squamous
epithelium
• Contains scattered and specialized
cells
• Lines exchange surfaces of alveoli
The Respiratory Defense System
• Consists of a series of filtration
mechanisms
• Removes particles and pathogens
Components of the Respiratory
Defense System
1. Mucus
– From goblet cells and glands in lamina propria,
traps foreign objects
2. Cilia “mucus escalator”
– Move carpet of mucus with trapped debris out
of the respiratory tract
3. Alveolar macrophages
– Phagocytose particles that reach alveoli
4. Filtration in nasal cavity removes large particles
Disorders of the
Respiratory Defense System
1. Cystic fibrosis
– Cause  Failure of mucus escalator
– Result  Produce thick mucus which blocks
airways and encourages bacteria growth
2. Smoking  destroys cilia
3. Inhalation of irritants  chronic
inflammation  cancer e.g. squamous cell
carcinoma
The upper respiratory system
and their functions.
The Upper Respiratory System
1. Nose
2. Nasal Cavity
3. Pharynx
-Nasopharynx
-Oropharynx
-Laryngopharynx
Figure 23–3
1. The Nose
• Only external feature
• Air enters the respiratory system:
– through external nares
– into nasal vestibule
• Space in flexible part, lined with hairs to
filter particles, leads to nasal cavity
• Nasal hairs in nasal vestibule are the first
particle filtration system
1. The Nose
• Functions
1.
2.
3.
4.
5.
Opening to airway for respiration
Moisten and warm entering air
Filter and clean inspired air
Resonating chamber for speech
Houses olfactory receptors
2. The Nasal Cavity
• The nasal septum:
– divides nasal cavity into left and right
• Superior portion of nasal cavity is the olfactory
epithelium  provides sense of smell
• Nasal conchae (superior, middle, inferior) project into
cavity on both sides
– Nasal conchae cause air to swirl
1. Increase likelihood of trapping foreign material in
mucus
2. Provide time for smell detection
3. Provide time and contact to warm and humidify
air
2. The Nasal Cavity
• Hard and soft palate form floor
• Internal nares open to nasopharynx
• Mucosa has large superficial blood supply
– Function  warm, moisten air
– Epistaxis = nose bleed
• Paranasal sinuses in frontal, sphenoid, ethmoid, and
maxillary bones
– Lined with respiratory mucosa
– Connected to nasal cavity
– Aid in warming/moistening air
2. The Nasal Cavity
• Hard palate:
– forms floor of nasal cavity
– separates nasal and oral cavities
• Soft palate:
– extends posterior to hard palate
– divides superior nasopharynx from lower
pharynx
• Air flow  Nasal cavity opens into
nasopharynx through internal nares
3. The Pharynx
• A chamber shared by digestive and
respiratory systems
• Extends from internal nares to
entrances to larynx and esophagus
• Three Parts:
1. Nasopharynx
2. Oropharynx
3. Laryngopharynx
3. The Pharynx
1. Nasopharynx = air only
- Posterior to nasal cavity
- Pseudostratified columnar epithelium
– Closed off by soft palate and uvula during
swallowing
– Pharyngeal tonsil located on posterior wall
• Inflammation can block airway
– Auditory tubes open here
2. Oropharynx = food and air
– Posterior to oral cavity
– Stratified squamous epithelium
– Palatine and lingual tonsils in mucosa
3. The Pharynx
3. Laryngopharynx = food and air
- Lower portion
- Stratified squamous epithelium
- Continuous with esophagus
Why is the vascularization of the nasal
cavity important?
A.
B.
C.
D.
It heats incoming air.
It moisturizes incoming air.
It nourishes nasal epithelial cells.
All of the above.
Why is the lining of the nasopharynx
different from that of the oropharynx
and the laryngopharynx?
A. Nasopharynx lining is not subjected
to food abrasion.
B. Nasopharynx lining must withstand
temperature extremes.
C. Nasopharynx must be protected
from drying out.
D. All of the above.
The lower respiratory system
and their functions.
Air Flow
• From the pharynx enters the larynx:
– a cartilaginous structure that surrounds
the glottis
4. Larynx
Figure 23–4
4. Larynx = voice box
• Hyaline cartilage around glottis
– Opening form laryngopharynx to trachea
• Functions of larynx
1. Provide continuous airway
2. Act as switch to route food and air properly
3. Voice production
• Contains epiglottis
– Elastic cartilage flap  covers glottis during
swallowing
The Glottis
Figure 23–5
4. Larynx = voice box
• Folds of epithelium over ligaments of elastic
fibers create focal folds/cords
• Vocal cords project into glottis
• Air passing through glottis vibrates folds producing
sound
• Pitch  Controlled by tensing/relaxing of the
cords
• Tense + narrow = high pitch
• Volume  Controlled by the amount of air
• Sound Production  phonation
4. Larynx = voice box
• Speech
– Formation of sound using mouth and tongue
with resonance in pharynx, mouth, sinuses and
nose
• Laryngitis
– Inflammation of vocal folds
– Cause  infection or overuse that can inhibit
phonation
When the tension in your vocal folds
increases, what happens to the pitch of
your voice?
A.
B.
C.
D.
It rises.
It falls.
Nothing happens.
It squeaks and cracks.
5. Trachea
Figure 23–6
The Trachea
• Attached inferior to larynx
• Walls composed of three layers
1. Mucosa
• Pseudostratified columnar epithelium, goblet
cells, lamina propria, smooth muscle and glands
2. Submucosa
• CT with additional mucus glands
3. Adventitia
• CT with hyaline cartilage rings (15-20)  keep
airway open, C-shaped
• Opening toward the esophagus to allow
expansion, ends connected by trachealis muscle
6. Primary Bronchi
• Trachea branches into the Right and
left primary bronchi
• Similar structure as trachea
– No trachealis muscle
• Right = steeper angle
• Enter lungs at groove (hilus)
– Along with blood and lymphatic
Hilus
• Where pulmonary nerves, blood
vessels, and lymphatics enter lung
• Anchored in meshwork of connective
tissue
Gross Anatomy of the Lungs
Right = 3 lobes
Left = 2 lobes
Figure 23–7
6. Primary Bronchi
• Lungs have lobes separated by deep fissures
• Inside lungs bronchi branch, get smaller in
diameter
– Branch ~23 times creating the bronchial tree
• As bronchi get smaller, structure changes
1. Less cartilage in adventitia
2. More smooth muscle in lamina propria
3. Epithelium is thinner, less cilia, less mucus
Bronchitis
• Inflammation of bronchial walls:
– causes constriction and breathing
difficulty
Relationship between
Lungs and Heart
Figure 23–8
7. Terminal
bronchiole
Smallest bronchi
of Respiratory Tree
Figure 23–9
7. Terminal bronchiole
•
•
•
•
Smallest Bronchi
No cartilage
Last part of conduction portion
Trachea, Bronchi and Bronchioles innervated
by ANS to control airflow to the lungs
– ANS Regulates smooth muscle:
• controls diameter of bronchioles
• controls airflow and resistance in lungs
– Sympathetic  bronchodilation
– Parasympathetic  bronchocontriction
• histamine release (allergic reactions)
Asthma
• Excessive stimulation and
bronchoconstriction
• Activated by inflammatory chemicals
(histamine)
• Stimulation severely restricts airflow
• Epinephrine inhaler mimics
sympathetic ANS  bronchodilation
7. Terminal bronchiole
• Each terminal bronchiole delivers air to
one pulmonary lobule, separated by CT
• Inside lobule, terminal bronchiole
branches into respiratory bronchioles
– No cilia or mucus
• Each respiratory bronchiole connects to
alveolar sac made up of many alveoli
The Bronchioles
Figure 23–10
8. Alveoli
Figure 23–11
8. Alveoli
• Wrapped in capillaries
• Held in place by elastic fibers
• Three cell types
1. Type 1 cells = gas exchange
• Simple squamous epithelium, lines inside
2. Type II cells = surfactant
• Cuboidal epithelial cells produce surfactant
– Phospholipids + proteins
– Prevent alveolar collapse, reduces surface
tension
3. Alveolar macrophages = Phagocytosis
• Phagocytosis of particles
8. Alveoli
• Alveoli connected to neighbors by alveolar
pores
– Equalize pressure
• Gas exchange occurs across the respiratory
membrane (0.5µm thick)
• 3 Parts of the Respiratory Membrane
1. Squamous epithelial lining of alveolus
2. Endothelial cells lining an adjacent capillary
3. Fused basal laminae between alveolar and
endothelial cells
Respiratory Distress
• Difficult respiration:
– due to alveolar collapse
– caused when septal cells do not produce
enough surfactant
Disorders of the Alveoli
1. Pneumonia:
– Inflammation of lungs from infection or
injury
– causes fluid to leak into alveoli
– compromises function of respiratory
membrane  prevents gas exchange
2. Pulmonary embolism
– Block in branch of pulmonary artery
– Reduce blood flow
– Causes alveolar collapse
Gross Anatomy of Lungs
Figure 23–8
Gross Anatomy of Lungs
•
•
•
•
Concave base, rest on diaphragm
Right = 3 lobes
Left = 2 lobes (accommodates heart)
Housed in pleural cavity
– Cavity lined with parietal pleura
– Lungs covered by visceral pleura
• Both pleura produce serous pleural fluid to reduce
friction during expansion
• Pleurisy
– Inflammation of pleura
– Restrict movement of lungs  breathing difficulty
Why are the cartilages that reinforce the
trachea C-shaped?
A. To prevent tracheal crushing.
B. To conform to thoracic cavity shape.
C. To allow room for esophageal
expansion.
D. To allow normal cardiac functioning.
What would happen to the alveoli if
surfactant were not produced?
A.
B.
C.
D.
The alveoli would contract.
The alveoli would collapse.
The alveoli would expand.
The alveoli would pop.
What path does air take in flowing
from the glottis to the respiratory
membrane?
A. larynx, trachea, bronchi, alveolar duct,
alveolar sac, respiratory membrane
B. larynx, trachea, alveolar duct,
bronchioles, respiratory membrane
C. trachea, bronchi, larynx, bronchioles,
alveolar duct, alveolar sac,
D. larynx, trachea, bronchioles, alveolar
duct, bronchi, alveolar sac, respiratory
membrane
List the functions of the pleura.
What does it secrete?
A. prevents cardiac friction; secretes
mucus
B. prevents respiratory friction; secretes
pleural fluid
C. protects lungs from drying out;
secretes mucus
D. protects heart and thoracic cavity;
secretes enzymes
Respiratory Physiology
Respiration
• External Respiration
– Includes all processes involved in
exchanging O2 and CO2 with the
environment
• Internal Respiration
– Also called cellular respiration
– Involves the uptake of O2 and production
of CO2 within individual cells
External Respiratory Physiology
• 3 steps of respiration
1. Pulmonary ventilation = breathing
2. Gas Diffusion/Exchange, across
membranes and capillaries
3. Gas Transport to/from tissues
– between alveolar capillaries
– between capillary beds in other tissues
1. Pulmonary Ventilation
• Movement of air into/out of alveoli
• Visceral pleura adheres to parietal pleura
via surface tension
– Altering size of pleural cavity will alter size of
lungs
• Pneumothorax
– Injury of thoracic cavity
– Air breaks surface tension  lung recoil =
atelectasis, or collapsed lung
1. Pulmonary Ventilation
• Mechanics of breathing
– Boyle’s law: gas pressure is inversely
proportional to volume
• Defines the relationship between gas pressure
and volume:
P = 1/V
– Air flows from area of high pressure to low
pressure
Gas Pressure and Volume
Figure 23–13
Mechanisms
of Pulmonary
Ventilation
Figure 23–14
Mechanisms of Pulmonary Ventilation
Diaphragm
• Contraction of diaphragm pulls it toward abdomen
– Lung volume INCREASE
– Air pressure DECREASE
– Air flow ins
• Relaxation causes diaphragm to rise in dome shape
– Lung volume DECREASE
– Air pressure INCREASE
– Air flows out
Rib cage movements can contribute
– Superior = bigger, air in
– Inferior = smaller, air out
Common Methods of
Reporting Gas Pressure
Table 23–1
Pressure and Volume Changes
with Inhalation and Exhalation
Figure 23–15
Factors influencing pulmonary ventilation
1. Airway resistance
– Diameter of bronchi
– Obstructions
2. Alveolar surface tension
– Surfactant (Type II cells) reduces alveoli
surface tension
• Allow inflation
– Respiratory distress syndrome
• Too little surfactant  requires great
force to open alveoli to inhale
Factors influencing pulmonary ventilation
3. Compliance
– Effort required to expand lungs and chest
– High compliance = expand easily, normal
– Low compliance = resist expansion
– Compliance affected by
1. CT structure
2. Alveolar Expandability
3. Mobility of thoracic cage
Factors influencing pulmonary ventilation
3. Compliance affected by
1. CT structure
- Loss of elastin/replacement by fibrous tissue =
Decrease compliance
- Emphysema
- respiratory surface replaced by scars
- Decrease elasticity = Decrease compliance
- Loss of surface for gas exchange
2. Alveolar Expandability
- Increase surface tension (decr. Surfactant) =
decrease compliance
- Fluid (edema) = decrease compliance
Factors influencing pulmonary ventilation
3. Compliance affected by
3. Mobility of thoracic cage
- less mobility = decrease compliance
Inspiration
• Inhalation involves contraction of muscles to
increase thoracic volume
1. Quite breathing = eupnea
– Diaphragm: moves 75% of air
– External intercostals: elevate ribs, 25%more
2. Forced breathing = hyperpnea
– Maximum rib elevation increases respiratory
volume 6x
• Serratus anterior, pectoralis minor,
scalenes, sternocleidomastoid
The Respiratory Muscles
Figure 23–16a, b
Expiration
1. Eupnea
– Passive, muscles relax, thoracic volume
decrease
2. Hyperpnea
– Abdominal muscles (obliques, transversus,
rectus) contract forcing diaphragm up,
thoracic volume further decrease
The Respiratory Muscles
Figure 23–16c, d
Respiratory Volumes and Capacities
Figure 23–17