Exam 2 Flashcards
Functions of the respiratory system
- Gas exchange – intake of O2 for delivery to body cells and removal of CO2 produced by body cells
- Contains receptors for the sense of smell, filters inspired air, produces sound, and excretes small amounts of water and heat
- Helps regulate blood pH
Organization of the respiratory system
Structurally
1. Upper respiratory tract
2. Lower respiratory tract
Functionally
1. Conduction zone
2. Respiratory zone
Pharynx
- Nasopharynx
- Oropharynx
- Laryngopharynx
Larynx
- Short tube of cartilage
- Connects pharynx to the trachea
- Epiglottis prevents food and liquid from entering the larynx
- Vocal folds produce sounds during speaking and singing
Structures of voice production
- A column of air pressure is moved towards the vocal folds
- Air is moved out of the lungs and towards the vocal folds by coordinated action of the diaphragm, abdominal muscles, chest muscles, and rib cage
- Vocal fold vibration
Epiglottis
- Elastic cartilage
- Extends from back of tongue to top of thyroid cartilage
- Open when breathing
- Swallowing epiglottis tips to keep food out
Trachea
- Tubular passageway for air
- Bifurcates at the carina
- Supported by C-shaped cartilage
- Mucous membrane composed of ciliated columnar epithelium
Respiratory zone
- Where gas exchange occurs
Alveoli
- Type I alveolar cells – simple squamous – main site of gas exchange
- Type II alveolar cells – secrete alveolar fluid – keeps cells moist, contains surfactant (reduces surface tension)
- Alveolar macrophage – remove dust and other debris
- Around the alveoli, the pulmonary arteries and veins form lush networks of blood capillaries
The structure of the respiratory epithelium at different sites within the respiratory tract
- A respiratory mucosa, with mucous cells and the mucus escalator, lines the nasal cavity and the superior portion of the pharynx
- A stratified squamous epithelium lines the inferior portions of the pharynx, protecting the epithelium from abrasion and chemical attack
- A typical respiratory mucosa lines the conducting portion of the lower respiratory tract
- In the finer bronchioles, the epithelium becomes cuboidal
- The gas exchange surfaces consist of a delicate simple squamous epithelium. Here the distance between the air and the blood in adjacent capillaries is generally less than 1 um
Blood supply
- Pulmonary vessels unique
- Arteries = deoxygenated
- Veins = oxygenated
Pulmonary ventilation
Pulmonary ventilation → the flow of air between the atmosphere and lungs, which occurs due to differences in air pressure
Boyles law
- At a constant the amount of pressure exerted by a given mass of gas is inversely proportional to the size of its container
Inspiration
- Inspiratory muscles contract
- Thoracic cavity volume increases
- Lungs are stretched, and intrapulmonary volume increases
- Intrapulmonary pressure drops
- Air flows into the lungs
Expiration
- Inspiratory muscles relax
- Thoracic cavity volume decreases
- Lung’s recoil, intrapulmonary volume decreases
- Intrapulmonary pressure rises
- Air flows out of lungs
Daltan’s law
- Each gas in a mixture of gases exerts its own pressure as if no other gases were present
- P total = P gas 1 + P gas 2 + P gas 3
Henry’s law
- The quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility coefficient when the temperature remains constant
- When a mixture of gases is in contact with a liquid, each gas will dissolve in the liquid in proportion to its partial pressure
Partial pressure
- The pressure exerted by an individual gas in a mixture is its partial pressure
- A gas will diffuse from an area where its partial pressure is high to an area where its partial pressure is low
External respiration
- Diffusion of oxygen from the alveoli into pulmonary capillaries and the diffusion of carbon dioxide in the opposite direction
- Diffusion occurs because gas molecules move from areas of high concentration (pressure) to low concentration (pressure)
- O2 diffuses from alveolar air, where Po2 is 105mm Hg, into the blood in pulmonary capillaries, where Po2 is about 40mm Hg
- CO2 diffuses from the blood in the pulmonary capillaries, where Pco2 is 45mm Hg, into the alveolar air, where Pco2 is about 40mm Hg
Internal respiration
- Diffusion of oxygen from systemic capillaries into the tissue cells, and the diffusion of carbon dioxide in the opposite direction
- Diffusion occurs because gas molecules move from areas of high concentration (pressure) to low concentration (pressure)
- Cells are continually using O2 and producing CO2
- O2 levels within tissues are always lower than within blood
- CO2 level within tissues are always higher than within blood
The components of external respiration include
- Alveolar surface area
- Ventilation and perfusion matching
- Partial pressure gradients
Oxygen transport
- Dissolved in blood plasma (1.5%)
- Bound to hemoglobin (98.5%)
Carbon dioxide transport
- Dissolved in blood plasma (7%)
- Bound to hemoglobin (23%)
- Transported as bicarbonate (70%)
Control of breathing
- The size of the thoracic cavity is altered by the action of the inspiratory muscles
- These muscles contract as a result of nerve impulses from the brain stem (respiratory center)
- Central chemoreceptors (medulla oblongata) respond to changes in PCO2 and/or h+
- Peripheral chemoreceptors (aorta and carotid arteries) respond to changes in PO2, PCO2, and/or h+
Neural control
Respiratory centres
- Responsible for generating and maintaining the rhythm of respiration
- Adjusting homeostatic response to physiological changes
Medullary
- Dorsal respiratory group – fundamental role in the control of respiration, initiating inspiration
- Ventral respiratory group – exhalation area of respiratory control
Pontine
- Smooth transitions between inspiration and expiration
Layers of heart wall
- Epicardium (outer) visceral serous pericardium
- Myocardium (middle) - cardiac muscle
- Endocardium (inside) - smooth endothelial layer
Right atrium
- Superior vena cava (from upper body)
- Inferior vena cava (from lower body)
- Pumps blood to right ventricle