APPP 18: Respiratory Systems Flashcards
What are the functions of the respiratory system? (6)
- gas exchange – intake O2 to convert nutrients to energy, eliminate toxic CO2
- helps regulate blood pH
- filters inspired air
- contains receptors for sense of smell
- produces vocal sounds
- excretes small amounts of water/heat in exhaled air
What are the structures of the upper respiratory system? (3)
- nose
- pharynx (throat)
- larynx (voice box)
What are the structures of the lower respiratory system? (3)
- trachea (windpipe)
- bronchi
- lungs
What is the conducting zone and what structures are a part of it?
cavities and tubes that filter, warm, and moisten air to ‘conduct’ air to the lungs
- nose
- pharynx
- larynx
- trachea
- bronchi
- bronchioles
- terminal bronchioles
What is the respiratory zone and what structures are a part of it?
tissues within lungs where gas exchange between air and blood occurs
- respiratory bronchioles
- alvelolar ducts
- alveolar sacs
- alveoli
Describe the structure of the external nose.
- 2 external nares (nostrils)
- made up of bone and hyaline cartilage that is covered with skin/muscle and lined by mucous membrane
Describe the structure of the internal nose.
- large cavity that extends from external nose to pharynx
- lined with muscle and mucous membranes
What are the functions of the nose? (3)
- warm, moisten, and filter air
- detect smells through olfactory receptors,
- modify sound
Describe the structure of the pharynx.
- funnel-shaped tube made out of skeletal muscle and mucous membrane
- around 13 cm (5 in) long
- located between nasal cavity and larynx
What are the 3 anatomical structures of the pharynx?
- nasopharynx
- oropharynx
- laryngopharynx
What is the nasopharynx?
- receives air from nasal cavity that contains dust-laden mucus
- lined with cilia that moves mucus (produced by goblet cells) down
- helps to equalize air pressure between ear and pharynx by exchanging small amounts of air through auditory tubes
What is the oropharynx?
- opens to the mouth
- has both digestive and respiratory function
What is the laryngopharynx?
- opens into the esophagus (food) and larynx (air)
- has both digestive and respiratory function
What are the functions of the pharynx? (3)
- passageway for food and air (respiratory and digestive functions)
- resonating chamber for sound (voice production)
- houses tonsils (involved in immune response)
Describe the structure of the larynx.
- connects laryngopharynx to trachea
- composed of 9 pieces of cartilage, including thyroid cartilage (Adam’s apple) and muscles that connect the cartilage to each other or other structures in the throat
- contains epiglottis – covers larynx to prevent food/liquids from travelling into trachea and airways
- contains vocal cords – create sound
What are the functions of the larynx? (2)
- connects upper and lower respiratory tracts
- voice production
What is laryngitis?
inflammation of the larynx most often caused by respiratory infections or environmental irritants (smoking)
- inflammation of vocal cords causes swelling, leading to a hoarse voice
Describe the structure of the trachea.
- tubular passageway for air that extends from larynx to 5th thoracic vertebra, where it divides into left and right primary bronchi
- composed of 16-20 incomplete ‘C-shaped’ horizontal rings of hyaline cartilage that provide a semi-rigid support
- open part of the ‘C shape’ faces the esophagus (is anterior to it) to allow for expansion of esophagus into trachea when swallowing
What procedure may be performed when airflow is blocked by obstruction of the trachea? (2)
- tracheotomy: insertion of a metal/plastic tracheal tube
- intubation: insertion of a tube into mouth/nose and down larynx into the trachea
What is the structure of the bronchial tree?
- trachea
- primary bronchi
- secondary bronchi
- tertiary bronchi
- bronchioles
- terminal bronchioles
Describe the structure of the bronchi.
- left and right primary bronchi are also made of incomplete rings of cartilage
- right primary bronchus is more vertical, shorter, and wider than the left – more likely for things to aspirate into the right
- once entering the lungs, primary bronchi become secondary bronchi – one for each lobe of the lung (right lung has 3 lobes, left lung has 2 lobes)
- secondary bronchi become tertiary bronchi
- tertiary bronchi become bronchioles
- bronchioles become terminal bronchioles
What are the 2 structural changes that occur during the branching of the bronchial tree (from trachea to terminal bronchioles)?
- mucous membrane goes from ciliated to non-ciliated
- incomplete C rings of cartilage become plates of cartilage, then no cartilage (instead, smooth muscle surrounds the lumen and muscle spasms (like in asthma) can close off airways
What are the pleural membranes?
two layers of serous membrane that enclose/surround and protect the lung
- parietal pleura: lines wall of thoracic cavity
- visceral pleura: covers lungs
What is the pleural cavity and what is its function?
- located between pleural membranes
- contains a small amount of fluid that is secreted by the membranes
- function is to reduce friction and allow membranes to slide easily over each other when breathing
Describe the differences between the left and right lungs. (4)
- left is 10% smaller due to location of heart
- right is slightly shorter due to diaphragm being higher on right side to accommodate the liver
- right has 3 lobes and left has 2 lobes
- fissures divide the lung into lobes – both lungs have an oblique fissure, but right lung also has horizontal fissue
What do terminal bronchioles divide into?
- respiratory bronchioles that penetrate into the lungs
- alveolar ducts
- alveolar sacs
- 2+ alveoli per sac that share a common opening
What are alveoli?
- sites of gas exchange
- walls contain two types of epithelial cells – type I alveolar cell and type II alveolar cell
- walls also contain alveolar macrophages
What are type I alveolar cells?
- more numerous
- form a nearly continuous lining
- main site of gas exchange
What are type II alveolar cells?
- fewer
- found in between type I alveolar cells
- have microvilli
- secrete alveolar fluid to keep the surface between cells and air moist
- alveolar fluid has surfactant, which lowers surface tension and reduces likelihood of alveoli collapse
What are alveolar macrophages?
- found in alveolar wall
- remove fine duct/debris from alveolar space
Where does O2 and CO2 exchange occur?
at the respiratory membrane
- extends from alveolar air space to blood plasma
- very thin to allow for rapid diffusion of gases
Describe the connection between the respiratory system and the cardiovascular system in gas exchange.
- network of blood capillaries surrounds outer surface of alveoli
- lung receives blood from pulmonary arteries – delivers deoxygenated blood to lungs, and returns to heart by pulmonary veins
- lung receives blood from bronchial arteries – delivers oxygenated blood to lungs, and returns to heart by superior vena cava
What are some other supportive structures of the respiratory system and what are their functions? (4)
- rib cage: protects lungs
- intercostal muscles: mechanical aspect of breathing
- diaphragm: primary muscle for breathing, innervated by phrenic nerves
- pleural cavity: surrounds lung and contains fluid that supports movement of lungs during breathing
Pulmonary Ventilation
What are the 3 basic steps of respiration?
- pulmonary ventilation (breathing): inhalation and exhalation of air from atmosphere into alveoli of lungs
- external (pulmonary) respiration: exchanges of gases (O2 and CO2) between alveoli in lungs and blood in pulmonary capillaries – occurs across respiratory membrane, pulmonary blood gains O2 and loses CO2
- internal (tissue) respiration: exchange of gases between blood in systemic capillaries and tissue cells – blood loses O2 and gains CO2, and cells use O2 for cellular respiration (to make energy)
Pulmonary Ventilation
What is Boyle’s law?
volume of a gas varies inversely with its pressure
- to decrease air pressure in lungs, increase volume
Pulmonary Ventilation
What drives inhalation?
air pressure inside alveoli needs to be lower than atmospheric pressure – air moves from high to low pressure into lungs
- contraction of diaphragm causes it to flatten, which increases volume of thoracic cavity, and decreases alveolar pressure
- external intercostal muscles contract – elevates ribs, increase in chest cavity, increases volume, decreases alveolar pressure
Pulmonary Ventilation
How much air is inhaled during normal quiet inhalation vs. strenuous breathing?
- normal quiet inhalation: diaphragm descends 1 cm – pressure difference of 1-3 mmHg, 500 mL of air inhaled
- strenuous breathing: diaphragm descends 10 cm – pressure difference of 100 mmHg, 2-3 L of air
(both types of breathing are ‘active’ processes because they involve muscle contraction)
Pulmonary Ventilation
What are accessory muscles?
muscles along the sternum and first 5 ribs that participate during strenuous breathing to increase the size of the thoracic cavity
Pulmonary Ventilation
Which structures are responsible for quiet breathing?
- contraction of diaphragm responsible for 75% of air that enters lungs
- external intercostals responsible for 25% of air that enters lungs
Pulmonary Ventilation
What is intrapleural pressure?
pressure between the two pleural membranes
- when diaphragm and intercostal muscles contract, plural cavity volume increases, and pressure within the pleural cavity decreases
Pulmonary Ventilation
Inhalation
- diaphragm contracts
- external intercostal muscles contract
- thoracic cavity increases in size
- volume of lungs expand
Pulmonary Ventilation
Exhalation
- diaphragm relaxes
- external intercostal muscles relax
- thoracic cavity decreases in size
- volume of lungs decreases
Pulmonary Ventilation
What drives exhalation?
pressure in lungs is greater than atmosphere – air moves from high to low, and exits lungs
- passive process – no muscle contraction involved (but can be active if muscles are required)
- due to elastic recoil of chest wall and lungs – diaphragm relaxes, external intercostals relax, lung volume decreases, alveolar pressure increases, air moves from high to low and leaves lungs
Pulmonary Ventilation
What are some other factors that influence pulmonary ventilation? (3)
- surface tension of alveolar fluid
- compliance of lungs
- airway resistance
Pulmonary Ventilation
What is lung compliance?
how much effort it takes to stretch lungs/chest wall
- normally lungs have high compliance due to elastic fibres in lung tissues and surfactant that reduces tension
- decreased lung compliance is a common feature in pulmonary disease
Pulmonary Ventilation
How does airway resistance affect ventilation?
rate of air flow depends on pressure and resistance
- as airways expand during inhalation, resistance decreases due to the increased diameter of the airway (also controlled by autonomic nervous system that causes relaxation of smooth muscle to increase diameter of airway)
- conditions that narrow/obstruct airway increase airway resistance and more pressure is needed to maintain airflow (ie. COPD and asthma)
Lung Volumes and Capacities
What is tidal volume?
volume of one breath
- 500 mL for average healthy adult
- around 70% reaches the respiratory zone
- around 30% remains in conducting airways (anatomic/respiratory dead space)
Lung Volumes and Capacities
What is respiratory rate?
number of breaths/minute
- 12 breaths/min for average healthy adult
Lung Volumes and Capacities
What is minute ventilation?
respiratory rate x tidal volume
- when this is lower than normal, it is a sign of pulmonary function
Lung Volumes and Capacities
What is a spirometer/respirometer?
an instrument used to measure respiratory rate and air exchanged during breathing
Lung Volumes and Capacities
What is inspiratory reserve volume (IRV)?
air that is inhaled during deep breath
Lung Volumes and Capacities
What is expiratory reserve volume (ERV)?
air that you can forcibly exhale beyond your tidal volume
Lung Volumes and Capacities
What is FEV1.0?
forced expiratory volume in 1 second – volume you can exhale from lungs in 1 second with max effort
- COPD decreases FEV1.0 because it increases airway resistance
Lung Volumes and Capacities
What is residual volume (RV)?
volume that remains in airways after forced exhalation
Lung Volumes and Capacities
What is inspiratory capacity (IC)?
tidal volume (TV) + inspiratory reserve volume (IRV)
Lung Volumes and Capacities
What is functional residual capacity (FRC)?
residual volume (RV) + expiratory reserve volume (ERV)
Lung Volumes and Capacities
What is vital capacity (VC)?
inspiratory reserve volume (IRV) + tidal volume (TV) + expiratory reserve volume (ERV)
Lung Volumes and Capacities
What is total lung capacity (TLC)?
vital capacity (VC) + residual volume (RV)
O2 and CO2 Exchange
Exchange of gases occurs via ___________ and is governed by what two gas laws?
passive diffusion
- Dalton’s law
- Henry’s law
O2 and CO2 Exchange
What is Dalton’s Law?
each gas in a mixture of gases exerts its own pressure as if all other gases were not present
- the pressure exerted by a gas in a mixture of gases is the partial pressure
O2 and CO2 Exchange
What is Henry’s law?
quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility
O2 and CO2 Exchange
What is external respiration?
- diffusion of O2 from air in alveoli to blood in pulmonary capillaries
- diffusion of CO2 in blood of pulmonary capillaries to air in alveoli
O2 and CO2 Exchange
What is internal respiration?
- exchange of O2 from systemic capillaries to tissue
- exchange of CO2 from tissue to systemic capillaries
O2 and CO2 Exchange
What does gas exchange rate depend on? (4)
- differences in partial pressure from high to low
- surface area – larger SA results in more gas exchange
- diffusion distance – smaller distance results in more gas exchange
- rate of airflow into and out of lungs
Transport of O2 and CO2
How is O2 carried to tissues? (2)
- most is bound to hemoglobin of RBCs – heme portion of Hb has 4 atoms of iron, and each atom can bind to a molecule of O2
- small amount is dissolved in blood – can diffuse into capillaries and tissues
Transport of O2 and CO2
What does the binding of O2 to Hb depend on? (5)
- partial pressure of O2: lower PO2 → less O2 combined with Hb
- acidity/pH: low pH → less O2 combined with Hb
- partial pressure of CO2: higher PCO2 → low pH → less O2 combined with Hb
- temperature: higher temperature → less O2 combined with Hb
- 2,3-biphosphoglycerate (BPG): higher BPG → less O2 combined with Hb
Transport of O2 and CO2
What causes carbon monoxide poisoning?
CO can bind to heme of Hb with 200x more affinity than O2
Transport of O2 and CO2
How is CO2 transported in blood plasma? (3)
- dissolved CO2 (7%)
- Hb-CO2 (23%)
- HCO3- (70%)
Transport of O2 and CO2
What is the chloride shift?
- blood picks up CO2 and HCO3- accumulates in RBCs, creating a high to low concentration gradient
- HCO3- moves out of blood plasma and Cl- moves into RBCs
Control of Respiration
What is the respiratory centre in the brain?
group of neurons that cause respiratory muscles to contract
Control of Respiration
What are the sensory inputs? (3)
- mechanoreceptors – sensory information regarding mechanical status of lungs and chest
- metaboreceptors – stimulate breathing during exercise
- chemoreceptors – monitor PO2, pH, concentration of gases
Control of Respiration
What controls respiration?
neuronal and sensory systems communicate to respiratory muscles/lungs to control mechanics of respiration
What is asthma?
chronic inflammatory disease of the airway
- many different types with different triggers
- symptoms: shortness of breath, chest tightness/pain, wheezing when exhaling, coughing
What is chronic obstructive pulmonary disease (COPD)?
progressive lung disease
- most common conditions: emphysema and chronic bronchitis
- symptoms: shortness of breath, increasing difficulty with daily activities
What is cystic fibrosis (CF?)
inherited disorder that affects cells that produce mucus, sweat, and digestive fluids
- most fatal genetic disease
- leads to severe damage to lungs, digestive system, and other organs
- symptoms: respiratory and digestive
