Respiratory System (Pt.1) Flashcards
What is the primary role of the respiratory system in homeostasis?
It facilitates gas exchange—oxygen and carbon dioxide—among atmospheric air, blood, and tissue cells, and helps adjust the pH of body fluids.
What happens during breathing (pulmonary ventilation)?
You breathe in oxygen and breathe out carbon dioxide.
What occurs during external respiration (lung exchange)?
Oxygen moves from the lungs into the blood, and carbon dioxide moves from the blood into the lungs.
What takes place during internal respiration (cell exchange)?
Oxygen moves from the blood into cells, and carbon dioxide moves from cells into the blood.
How does the respiratory system contribute to blood pH regulation?
By controlling the levels of carbon dioxide in the blood, which affects acidity.
What additional functions does the respiratory system perform?
It enables smell, filters air, makes sounds, and releases water and heat.
How do the respiratory and circulatory systems work together?
They provide oxygen to cells and remove waste carbon dioxide to keep cells healthy.
Why is it important to remove carbon dioxide from the body?
Too much carbon dioxide is harmful, so it must be removed to prevent toxicity.
What happens if either the respiratory or circulatory system fails?
Cells can quickly die from lack of oxygen and the buildup of waste products.
What is respiration?
The exchange of gases between the atmosphere, blood, and cells.
How does the cardiovascular system help the respiratory system?
By transporting gases in the blood.
How many processes are required for respiration to occur?
Three processes.
What are the three processes of respiration?
- Ventilation (breathing) 2. External (pulmonary) respiration 3. Internal (tissue) respiration
What is another term for ventilation?
Breathing
What is another term for external respiration?
Pulmonary respiration
What is another term for internal respiration?
Tissue respiration
What is pulmonary ventilation and what happens during this process?
It’s breathing - inhalation brings oxygen in and exhalation removes carbon dioxide, exchanging air between atmosphere and alveoli.
What happens during inhalation?
Oxygen-rich air enters through nose/mouth, travels down windpipe, into lungs, and reaches alveoli.
What happens during external respiration?
Gases are exchanged between alveoli and pulmonary capillaries - blood gains oxygen and loses carbon dioxide.
Where does external respiration occur?
In the lungs.
What happens during internal respiration?
Gases are exchanged between systemic capillaries and tissue cells - blood loses oxygen and gains carbon dioxide.
Where does internal respiration occur?
Throughout the body in tissue cells.
Can you control pulmonary ventilation?
Yes, it’s the only part of respiration you can consciously control.
Are external and internal respiration automatic processes?
Yes, both happen automatically without conscious control.
Using the delivery system analogy, what represents the ‘trucks’?
Blood vessels represent the ‘trucks’ that transport oxygen and carbon dioxide.
Using the delivery system analogy, what are the ‘packages’?
Oxygen represents the ‘packages’ being delivered to cells.
Using the delivery system analogy, what is the ‘waste’?
Carbon dioxide represents the ‘waste’ that needs to be removed from cells.
What are the 4 main stages of the complete respiratory process?
- Pulmonary Ventilation 2. External Respiration 3. Gas Transport in Circulation 4. Internal Respiration
What happens to oxygen during pulmonary ventilation?
O₂ is brought into the lungs and enters the pulmonary alveoli (tiny air sacs).
Where does gas exchange occur during external respiration?
Between the alveoli and pulmonary capillaries (blood vessels in lungs).
What happens to blood composition during external respiration?
Blood gains O₂ and loses CO₂.
How is oxygen-rich blood transported through the body?
From lungs to heart, then pumped through systemic circulation.
What happens during internal respiration?
O₂ diffuses from blood into body cells, while CO₂ diffuses from cells into blood.
What is the purpose of oxygen in cellular respiration?
To convert nutrients into energy (ATP).
What is the complete path of oxygen in the respiratory system?
Atmosphere → lungs → bloodstream → tissues
What is the complete path of carbon dioxide in the respiratory system?
Tissues → bloodstream → lungs → atmosphere
What color are oxygen-rich blood vessels typically shown as in diagrams?
Red
What color are carbon dioxide-rich blood vessels typically shown as in diagrams?
Blue
What are the two structural divisions of the respiratory system?
- Upper respiratory system
- Lower respiratory system
What structures make up the upper respiratory system?
• Nose
• Nasal cavity
• Pharynx (throat)
• Associated structures
What structures make up the lower respiratory system?
• Larynx (voice box)
• Trachea (windpipe)
• Bronchi
• Lungs
What are the two functional zones of the respiratory system?
- Conducting zone
- Respiratory zone
What is the main purpose of the conducting zone?
To filter, warm, and moisten air
List the parts of the conducting zone.
• Nose
• Nasal cavity
• Pharynx
• Larynx
• Trachea
• Bronchi
• Bronchioles
• Terminal bronchioles
What is the main purpose of the respiratory zone?
Gas exchange between air and blood
List the parts of the respiratory zone.
• Respiratory bronchioles
• Alveolar ducts
• Alveolar sacs
• Pulmonary alveoli
What is another name for the larynx?
Voice box
What is another name for the trachea?
Windpipe
What is another name for the pharynx?
Throat
What are the main components of the upper respiratory system?
The nose, nasal cavity, pharynx, and associated structures
What are the three types of nasal conchae?
Superior, Middle, and Inferior conchae
What is the function of nasal conchae?
They increase surface area to help filter, warm, and humidify inhaled air
What are the three regions of the pharynx?
- Nasopharynx 2. Oropharynx 3. Laryngopharynx
Where is the olfactory epithelium located and what is its function?
Located in the superior nasal cavity; responsible for detecting odors
What is the function of the epiglottis?
Prevents food from entering the airway during swallowing
What are the two types of vocal folds?
True vocal cords (for sound production) and false vocal cords (for protection and pressure regulation)
What is the function of sinuses?
They reduce skull weight and enhance voice resonance
What are the four main functions of the upper respiratory structures?
- Air preparation 2. Pathway for air and food 3. Sound production 4. Protection
What structure directs food and air to their proper pathways?
The pharynx (throat)
What is the framework of the external nose made of?
Bone (facial bones) and hyaline cartilage, joined by fibrous connective tissue and lined with a mucous membrane.
What are the three functions of the internal structures of the external nose?
- Warm, moisten, and filter incoming air 2. Detect olfactory stimuli 3. Modify speech vibrations
What are the two main parts of the nose?
- External Nose 2. Internal Nose (Nasal Cavity)
What does the external nose consist of?
Bone and flexible cartilage, covered by skin and lined with a mucous membrane.
What supports the external nose?
The frontal bone, nasal bones, and maxillae (upper jawbone).
Where is the internal nose located?
Inside the skull.
What is a primary function of the nose related to air management?
To warm, moisten, and filter the air you breathe in.
How does the nose contribute to the sense of smell?
It contains olfactory receptors for sensing odors.
What role does the nose play in communication?
It modifies sounds as they pass through the nasal cavity, enhancing speech.
Why is the nose important in respiration?
It plays crucial roles in warming, filtering, and humidifying inhaled air.
What are the three main regions of the pharynx?
- Nasopharynx (Upper) 2. Oropharynx (Middle) 3. Laryngopharynx (Lower)
What is the primary lining of the nasopharynx?
Ciliated pseudostratified columnar epithelium
What does the oropharynx connect?
It is located behind the oral cavity and contains the opening to the mouth (fauces).
What types of tonsils are found in the oropharynx?
Palatine tonsils and lingual tonsils
What structures does the laryngopharynx open to?
The esophagus (for food) and the larynx (for air).
How long is the pharynx?
Approximately 13 cm long.
What type of immune tissue is housed within the pharynx?
Tonsils
What is the basic definition of the larynx?
A passageway connecting the throat (pharynx) to windpipe (trachea), containing structures for voice production
Where is the larynx located?
In the midline of neck, in front of esophagus, level with vertebrae C4-C6
How many cartilage pieces make up the larynx?
9 cartilage pieces
What are the three single cartilages in the larynx?
Thyroid (Adam’s apple), Epiglottic, and Cricoid
What are the three paired cartilages in the larynx?
Arytenoid, Cuneiform, and Corniculate
What is the function of the epiglottis?
Acts like a trapdoor to prevent food/drink from entering the airway
What is the main function of vocal folds?
To produce voice through vibration
What is the function of vestibular folds?
Help with breath holding
What are the three main functions of the larynx?
- Voice production 2. Airway protection 3. Breathing maintenance
What components make up the framework of the larynx?
Cartilage pieces, muscles (intrinsic and extrinsic), and mucous membrane lining
What is the function of the epiglottis?
Prevents food and liquids from entering the respiratory system during swallowing.
How does the epiglottis move when swallowing?
It flips backward to cover the larynx.
What type of tissue makes up the epiglottis?
Elastic cartilage covered with mucous membrane.
What epithelium lines the area above and below the vocal folds?
Stratified squamous above; ciliated pseudostratified columnar below.
Why is the epiglottis important for digestion and respiration?
It directs food to the esophagus and protects the airway.
What can happen if the epiglottis malfunctions?
Food may enter the larynx, causing choking or aspiration.
How long and wide is the trachea?
About 12 cm long and 2.5 cm in diameter
Where does the trachea extend from and to?
From the larynx to the primary bronchi (at T5)
What are the four layers of the tracheal wall (deep to superficial)?
- Mucosa 2. Submucosa 3. Hyaline cartilage 4. Adventitia
What type of epithelium lines the trachea?
Ciliated pseudostratified columnar epithelium
How many cartilage rings are in the trachea?
16-20 C-shaped rings
Why are the cartilage rings C-shaped?
To allow flexibility and efficient airflow, with open side facing esophagus
What is the function of the trachealis muscle?
Allows subtle diameter changes during breathing
What cells in the mucosa produce mucus?
Goblet cells
What is the main function of the cartilage rings?
To keep the trachea open and prevent collapse
Where is the trachea located in relation to the esophagus?
Anterior to (in front of) the esophagus
Where does the trachea branch into primary bronchi?
At the superior border of T5
What is the carina?
The internal ridge where trachea divides into bronchi; sensitive for triggering cough reflex
How does the right primary bronchus differ from the left?
It’s shorter, wider, and more vertical
What is the branching pattern of bronchi (in order)?
Primary → Lobar (Secondary) → Segmental (Tertiary) → Bronchioles → Terminal Bronchioles
How many lobes do the bronchi supply in each lung?
3 in the right lung, 2 in the left lung
What are Clara cells and where are they found?
Nonciliated exocrine cells in terminal bronchioles that produce protective substances
What type of epithelium lines the main bronchi?
Ciliated pseudostratified columnar epithelium
Why is the right bronchus more dangerous for inhaled objects?
Due to being shorter, wider, and more vertical, objects are more likely to get trapped there
How many generations of branching occur in the bronchial tree?
About 23 levels
What marks the end of the conducting zone?
Terminal bronchioles
What is the complete branching pattern of bronchi?
Primary → Lobar → Segmental → Bronchioles → Terminal bronchioles
What marks the end of the conducting zone?
Terminal bronchioles
How does epithelium change from main bronchi to terminal bronchioles?
Ciliated pseudostratified columnar → ciliated simple columnar → ciliated simple cuboidal → nonciliated simple cuboidal
What happens to cartilage structure along the bronchial tree?
C-rings become plates in bronchi and disappear in bronchioles
What happens to smooth muscle along the bronchial tree?
It increases, allowing airway control but making airways prone to spasms
What is the sympathetic effect on airways?
Relaxes smooth muscle, dilating airways
What is the parasympathetic effect on airways?
Contracts smooth muscle, narrowing airways
What structures are beyond terminal bronchioles?
Respiratory bronchioles and alveolar ducts
What is the main function of the conducting zone?
To filter, warm, and humidify air before it reaches gas exchange areas
How are particles removed in different areas?
Cilia and goblet cells in ciliated areas; macrophages in nonciliated areas
What are the lungs?
Paired, cone-shaped organs in the thoracic cavity that assist with breathing.
What layer encloses and protects the lungs?
The pleural membrane (double-layered serous membrane).
What is the pleural cavity?
The space between the visceral and parietal pleura containing lubricating fluid.
What are the two layers of the pleura?
- Parietal pleura (outer layer lining the chest wall) 2. Visceral pleura (inner layer covering the lungs)
What is the function of pleural fluid?
Reduces friction during breathing and helps membranes stick together due to surface tension.
What is pleurisy?
Inflammation of the pleura that causes pain.
What is pleural effusion?
Accumulation of excess fluid in the pleural space.
What is the base of the lung?
The wide bottom part that sits on the diaphragm.
What is the apex of the lung?
The narrow top portion.
How does the left lung differ from the right lung?
The left lung is smaller (10% smaller), has a cardiac notch for the heart, and is slightly longer.
How does the right lung differ from the left lung?
The right lung is thicker, broader, and shorter due to the liver below.
What is thoracentesis?
A medical procedure to remove excess fluid from the pleural cavity.
Where should the needle be inserted during a thoracentesis?
Through the 7th intercostal space, along the top of the rib to avoid blood vessels.
What is a lobule?
A component of bronchopulmonary segments containing connective tissue, lymphatic vessel, arteriole, and venule
What fissures are present in both lungs?
Oblique fissure
What additional fissure is only in the right lung?
Horizontal fissure
How many lobar bronchi are in each lung?
Right lung: 3 (superior, middle, inferior) Left lung: 2 (superior, inferior)
How many segmental bronchi are in each lung?
10 segmental bronchi
Where does the respiratory zone begin and end?
Begins after terminal bronchioles, ends at alveoli
What structures are included in the respiratory zone?
Respiratory bronchioles, alveolar ducts, alveolar sacs, and individual alveoli
What is the main difference between conducting and respiratory zones?
Conducting zone transports air only; respiratory zone performs gas exchange
What facilitates gas exchange in the respiratory zone?
Large surface area of alveoli, thin walls, and rich blood supply
How does gas exchange occur?
Through diffusion across thin alveolar walls - oxygen enters blood while carbon dioxide leaves
What makes up an alveolar sac?
20-30 alveoli in a grape-like cluster at the end of alveolar ducts
How many sacs are at the end of each duct?
About 100 sacs
What is the size of each alveolus?
0.2-0.3 mm wide
Compare Type I and Type II pneumocytes:
Type I: 95% of cells, thin, main gas exchange site
Type II: Fewer, rounded, produces surfactant and alveolar fluid
What structures are found in alveolar walls?
Alveolar macrophages, fibroblasts, and blood capillaries
What is the importance of surfactant?
Keeps alveoli open and functioning properly
What is the role of alveolar macrophages?
Clean up debris and fight bacteria as part of lung defense
What gives lungs their spongy texture?
The numerous alveoli
What makes gas exchange efficient in alveoli?
Large surface area and thin respiratory membrane
How is blood supplied to alveoli?
Through a rich network of capillaries with single layer of endothelial cells
What are the two types of alveolar cells?
Type I (pneumocyte type 1) and Type II (pneumocyte type 2 or septal cells).
What percentage of alveolar cells are Type I?
95%.
What is the function of Type I pneumocytes?
They are thin, flat cells that form most of the alveolar wall and are the main site for gas exchange (oxygen and carbon dioxide).
What is the structure and role of Type II pneumocytes?
Type II cells are fewer, rounded (cuboidal), contain microvilli, and produce:
Alveolar fluid: Keeps surfaces moist.
Surfactant: Reduces surface tension, preventing alveolar collapse.
How does surfactant affect the ease of breathing?
Surfactant makes it easier to inflate the alveoli, like blowing up a used balloon compared to a deflated one.
What are alveolar macrophages?
They act as the ‘cleaning crew’ in the alveoli, removing dust and debris and fighting off harmful bacteria.
How do Type I, Type II cells, and macrophages work together?
Type I cells manage gas exchange, Type II cells maintain the necessary moisture and surfactant, while macrophages keep the alveolar environment clean and safe.
What are the 4 layers of the respiratory membrane (in order from air to blood)?
- Alveolar wall (Type I/II cells + macrophages) 2. Epithelial basement membrane 3. Capillary basement membrane 4. Capillary endothelium
How thick is the respiratory membrane?
0.5 µm (16 times thinner than a red blood cell)
What structures make up the alveolar wall?
Alveolar macrophages, fibroblasts, elastic basement membrane, and blood vessels
What is the purpose of the respiratory membrane’s thinness?
To allow quick gas exchange between air and blood
Which gases move across the respiratory membrane?
Oxygen (air to blood) and carbon dioxide (blood to air)
How many alveoli are in the lungs?
300-500 million
What is the total surface area of alveoli?
75 m² (size of a racquetball court)
What gives lungs their spongy feel?
The many air sacs (alveoli)
What happens to the basement membranes?
The epithelial and capillary basement membranes are often fused together
What is the main purpose of this structure?
To facilitate efficient gas exchange between air in alveoli and blood in capillaries
What are the two circulatory systems in the lungs?
- Pulmonary circulation (for gas exchange) 2. Bronchial circulation (for lung tissue nourishment)
What is the path of pulmonary circulation?
Deoxygenated blood → pulmonary trunk → pulmonary arteries → alveoli → pulmonary veins → left atrium
What is the purpose of bronchial circulation?
To supply oxygen and nutrients to lung tissue and remove waste
Where does bronchial circulation originate?
Branches from the aorta
Do these two circulatory systems connect?
No, they remain separate
How is this similar to heart circulation?
Like how heart chambers pump blood (pulmonary) while coronary arteries feed heart tissue (bronchial)
How do pulmonary vessels uniquely respond to low oxygen?
They constrict (unlike other body vessels which dilate)
What is ventilation-perfusion coupling?
The process of redirecting blood to better-ventilated areas for efficient gas exchange
What is the key difference in purpose between the two systems?
Pulmonary circulation handles gas exchange, while bronchial circulation provides nourishment to lung tissue
What are the two ways blood enters the lungs?
- Pulmonary arteries (pulmonary circulation) 2. Bronchial arteries (systemic circulation)
How does blood exit the lungs?
Through pulmonary veins and bronchial veins
What is the purpose of pulmonary circulation?
Gas exchange in alveoli
What is the purpose of bronchial circulation?
To nourish lung tissue
What type of blood do pulmonary arteries carry?
Deoxygenated blood
What type of blood do bronchial arteries carry?
Oxygenated blood
What is ventilation-perfusion coupling?
A process where blood flow (perfusion) matches air flow (ventilation) in lung areas
How do blood vessels respond to poor ventilation?
They constrict and redirect blood to better-ventilated areas
Do the pulmonary and bronchial circulations connect?
No, they remain separate
What is the benefit of ventilation-perfusion coupling?
It optimizes gas exchange by ensuring blood flows to well-ventilated areas
What is intrapleural pressure?
The pressure within the pleural cavity between lung lining and chest wall
What are the pressure values at rest?
Atmospheric/Alveolar: 760 mmHg
Intrapleural: 756 mmHg
What happens during inhalation?
- Diaphragm contracts and flattens
- External intercostals lift rib cage
- Alveolar pressure drops to 758 mmHg
- Intrapleural pressure drops to 754 mmHg
What happens during exhalation?
- Diaphragm and external intercostals relax
- Chest cavity decreases
- Alveolar pressure increases to 762 mmHg
- Intrapleural pressure returns to 756 mmHg
Why does air flow into the lungs?
Air moves from high to low pressure when alveolar pressure drops below atmospheric pressure
What is the purpose of pleural fluid?
Allows smooth movement between lung and chest wall membranes and prevents friction
What is pulmonary ventilation?
Movement of air in and out of lungs due to pressure differences created by respiratory muscles
What are the three main factors influencing breathing effort?
- Alveolar surface tension 2. Lung compliance 3. Airway resistance
What happens during inhalation?
- Diaphragm contracts and moves down
External intercostal muscles contract
Chest cavity expands
Creates lower pressure, drawing air in
What happens during exhalation?
- Muscles relax
Diaphragm moves up
Ribs move down and in
Chest cavity shrinks
Air flows out
What is lung compliance?
How easily lungs expand, similar to a balloon’s stretchiness
What affects airway resistance?
Mucus
Inflammation
Bronchial constriction
Airway diameter
What is the role of surfactant in surface tension?
Reduces alveolar surface tension, preventing collapse and making breathing easier
When does air enter the lungs?
When pressure inside lungs is lower than atmospheric pressure
When does air exit the lungs?
When pressure inside lungs is higher than atmospheric pressure
How is airway resistance similar to drinking straws?
Like how wider straws have less resistance than narrow straws
