Chapter 7 Mammalian gas exchange Flashcards
What is a tissue?
Group of similar cells that are specialised to carry out a specific function
E.g. squamous epithelium, ciliated epithelium, xylem tissue, phloem tissue
Define an organ.
Group of tissues specialised to carry out specific functions
E.g. lungs, leaves
What is a system in biological terms?
Collection of organs with a specific function
E.g. circulatory system, gas exchange system
What is the primary function of the gas exchange system (GES)?
Diffusion of respiratory gases: CO2 out of and O2 into the bloodstream
What factors determine the rate of diffusion in the gas exchange system?
Surface area to volume ratio, distance, and metabolic rate
Why is a specialised gas exchange system needed in multicellular organisms?
Diffusion rate alone is too slow due to large diffusion distances and higher metabolic demands
What is the significance of the surface area of alveoli?
Huge surface area (~50-75m2) allows for more O2 and CO2 molecules to diffuse per unit time
What feature of alveoli reduces diffusion distance?
Single layer of thin, flat cells known as alveolar epithelium
What role does the capillary network around alveoli play?
Maintains concentration gradient and enables gas exchange in opposite directions
What maintains a steep diffusion gradient in the gas exchange system?
Pulmonary circulation and ventilation mechanism
What is the structure and function of the trachea?
Carries air from oral cavity to bronchi; held open by C-shaped rings of cartilage
What is the purpose of the rings of cartilage in the trachea and bronchi?
Provide support and prevent collapse during inhalation
What do bronchi do?
Carry air into/out of the respective lung
What defines bronchioles?
Subdivisions of bronchi with varying wall structures
What is the primary site of gas exchange?
Alveoli
What is the diameter of an alveolus?
Approximately 200-300 μm
What is the role of surfactant in the alveoli?
Reduces surface tension of water, preventing alveoli from sticking together
What do goblet cells secrete?
Mucus to trap pathogens and dust
What is the function of cilia in the respiratory system?
Waft mucus upwards towards the throat
What do elastic fibres do in the lungs?
Allow for stretch during inhalation and recoil during exhalation
What is pulmonary ventilation?
Movement of fresh air into lungs and removal of stale air
What happens during inspiration?
External intercostal muscles contract, diaphragm flattens, and thoracic volume increases
What is the tidal volume?
Volume of air that moves in and out with each normal breath (~0.5 dm3)
Define vital capacity.
Maximum volume of air that can be inhaled or exhaled (~3-5 dm3)
What is residual volume?
Volume of air remaining in the lungs after forced exhalation
What is the breathing rate?
Number of breaths taken in a given time period, usually one minute
What does pulmonary ventilation equal?
Tidal volume x breathing rate
What is forced expiratory volume in one second (FEV1)?
Volume of air forcibly exhaled in the first second of forced exhalation
What is peak expiratory flow rate (PEFR)?
Maximum rate of forced exhalation through the mouth
What can cause respiratory arrest?
Obstruction, drug overdose, asthma attack, severe pneumonia, severe shock, heart attack
What is the first step in treating respiratory arrest?
Call for help and open their airway
What is the purpose of rescue breaths in CPR?
To provide oxygen to the lungs when the person is not breathing
What does CPR involve?
Chest compressions and rescue breaths to maintain circulation
