D1 B. Respiratory System Flashcards
Breathing (or ventilation)
The process by which air enters and leaves the lungs
Respiration
All processes that supply oxygen to the cells of the body for the breakdown of glucose and the process by which CO2 is transported to the lungs for exhalation
3 Steps of Ventilation
- Ventilation (gas exchange between atmosphere and lungs)
- Gas exchange (transfer of gases between lungs and bloodstream)
- Cell respiration (release of ATP from organic molecules)
The Upper Respiratory System
Nasal Cavity
- Hair and mucus (filtering system)
- Mucus keeps cells lining the cavities moist
- Opens into the pharynx → branches into the treachea and esophagus
The Lower Respiratory System
Larynx (voice box)
- Upper end of trachea
- Elastic ligaments form the vocal cords which vibrate as air is forced past them
- Protected by thick cartilage (Adam’s apple)
The Lower Respiratory System
Trachea (wind pipe)
- Mucus (traps and filters)
- Ciliated cells (cilia - small hairs) sweep debris back to the pharynx
- Supported by rings of cartilage - keep trachea open
The Lower Respiratory System
Bronchi
- Has cartilage rings
- Carry air into the right and left lungs
- Branch into smaller airways called bronchioles (no cartilage)
The Lower Respiratory System
Alveoli
- Single layer of cells
- Surrounded by capillaries
- Gasses diffuse between thee air and blood according to the concentration gradients
- S.A. (150 million alveoli per lung)
- Lipoproteins prvents sacs from sticking to self during exhalation
Alveoli - Pneumocytes
Type I Pneumocytes
- Mediate gas exchange with capillaries and over ~95% of the alveolar surface
- Squamous (flat) and thin - minimizes diffusion rate
Alveoli - Pneumocytes
Type II Pneumocytes
- Secrete pulmonary surfacant which reduces surface tension in alveoli
- Cubodial in shape and possess granules (stores surfactant)
Surfactant
Surface tension is the force created by a fluid surface that minimizes surface area
Without Surfactant:
- More pressure (due to small radius)
With Surfactant:
- Less tension
Lung Lobes
The right lung has 3 lobes whereas the left lung has 2
Bronchiole
A branch off the bronchi
Diaphragm
- Dome shaped sheet of muscle
- Seperates thoracic (chest) cavity and abdominal cavity
- Inspiration - Muscle contracts and pulls downwards, chest volume increases, pressure in the lungs decreases
- Expiration - Diaphram relaxes and returns to its dome shape, chest volume decreases, and pressure increases
Epiglottis
Small, cartilage that protects larynx and helps you swallow
Pharynx
- Throat
- Passageway that is part of both the digestive and respiratory system
Thoracic Cavity
Space that contains the heart, lungs and other organs
Air flow through the respiratory system
- Air enters your body through nose or mouth
- Air travels down throat through larynx and trachea
- Air goes into lungs through larger tubes called bronchi
There are two bronchi; one that leads to each lung
- Air goes through bronchi into smaller bronchioles
- Bronchioles end in tiny sacs (alveoli) where gas exchange occurs
Breathe out Carbon Dioxide
Boyles Law
Pressure is inversely proportional to volume
- When volume in the thoracic cavity increase; pressure decreases (gas will flow in)
- When volume in the thoracic cavity decreases, pressure increases (gas will flow out)
Intercostal Muscle
- Muscle between the ribs, which raise and lower the rib cage
- Nerve stimulation causes muscle to contract, pulling ribs upward and outward, thus raising volume of the chest
Pleura of the lungs
2 thin layers of tissue that protect and cushion the lungs
- Inner layer wrapped around lungs
- Outer layer lines inside of chest wall
The fluid filled pleural cavity helps prevent friction as the lungs move agaisnt the walls of the thoracic cavity
Tidal Volume
Volume of air inhaled and exhaled in a normal breath (about 500mL)
Inspiratory Reserve Volume
The additional volume of air that can be inhaled
Expiratory Reserve Volume
The additional volume of air that can be exhaled (must be forced out of lungs)
Vital Capacity
Total volume of gas that can be moved in or out of lungs
Inspiratory Reserve Volume + Tidal Volume + Expiratory Reserve Volume
Vital Capacity
Residual Volume
Amount of air left in the lungs after max exhalation
Passive diffusion of gases
Oxygen: High in alveoli; low in capillaries
Carbon Dioxide: High in capillaries, low in alveoli
Avogadro’s Hypothesis
Equal volume of gases at the same temperature and pressure contain equal number of molecules
- As a result, gas diffuses from area of high pressure to an area of low pressure
Dalton’s Law of Partial Pressure
Gases in a mixture behave as if the other isn’t there exerting its own pressure (or partial pressure)
Oxygen Transport (Plasma)
- Through partial pressures, oxygen moves from the atmosphere into the alveoli then into the blood
- Plasma can only dissolve about 0.3 mL of oxygen/ 100 mL of blood
Hemoglobin
Allows 20 mL of oxygen/ 100 mL
3 Main Ways CO2 is Transported
Bicarbonate Ions
- Most CO2 produced from CR enters the blood plasma and combines with water to form carbonic acid
- Catalyzed by carbonic anhydrase
- Carbonic acid then dissociates to form bicarbonate ions and hydrogen ions
- Decrease the amount of CO2 in plasma therefore maintaining a low partial pressure
- H+ with hemoglobin, therefore buffering blood pH
3 Main Ways CO2 is Transported
Bound to Hemoglobin
- CO2 attaches to the globin part of the hemoglobin - carbaminohemoglobin
- (O2 carried on heme part so they don’t interfere with each other)
3 Main Ways CO2 is Transported
Dissolved in Plasma
CO2 is 20% more soluble than oxygen. Inefficient way to carry CO2
Maintaining Gas Levels
- Chemoreceptors in the aortic body and carotid body detect high levels of CO2 in the blood
- Sends message to the medullaa oblongata (in the brain)
- Message is sent to intercostal muscles and diaphragm to increase lung volume and breathing rate
- When CO2 levels return to normal breathing rate decreases
Regulation of Breathing Movements
- Nerves from the medulla oblongata (in the brain) control breathing rates
- Chemoreceptors detect changes in CO2 and O2, and acid levels in the blood
Two Types
- CO2 and Acid Chemoreceptors are the msot sensitive & main regulators of breathing movements
- O2 Chemoreceptors: Found in carotid and aorta
Types of Respiration
External Respiration
- In lungs
- Involves exchange of O2 and CO2 molecules between air and blood
- When you breathe in, partial pressure of O2 is higher in the alveoli than in the capillaries → O2 moves from the alveoli into the capillaries
Types of Respiration
Internal Respiration
- Within body
- Exchange of O2 and CO2 molecules between blood and tissue fluid
- O2 is used in cell resp. → Partial pressure gradient for O2 is low → O2 will go from the capillaries into the tissues
