Exchange Surfaces Flashcards
(30 cards)
Why do multicellular organisms need specialised exchange surfaces?
Due to increased size, lower SA:V ratio, and higher metabolic demands
What three factors affect the need for exchange surfaces?
Surface area to volume ratio, metabolic activity, whether single-celled or
multicellular.
What is the surface area to volume ratio formula?
surface area ÷ volume.
What are the features of an efficient exchange surface?
Large surface area. Thin barrier. Good blood supply or ventilation.
Why is a large surface area important for exchange?
Increases area for diffusion
Why is a thin barrier important for exchange?
Short diffusion path.
Why is a good blood supply or ventilation important for exchange?
Maintains steep concentration gradient
Which structures in humans, fish, and insects illustrate good blood supply/ventilation?
Root hair cells (SA), alveoli (thin), gills/alveoli (blood supply)
What is the function of cartilage in the mammalian gaseous exchange system?
Provides structural support.
What is the function of ciliated epithelium in the gaseous exchange system?
Moves mucus
What is the function of goblet cells?
Secretes mucus to trap particles.
What is the function of smooth muscle in the airways?
Controls airway diameter.
What is the function of elastic fibres in the lungs?
Allows stretch and recoil.
Where are these tissues found in the trachea, bronchi, bronchioles, and alveoli?
Trachea/bronchi: cartilage, cilia, goblet, muscle, elastic. Bronchioles: smooth
muscle, elastic. Alveoli: elastic fibres only.
What is the mechanism of ventilation in mammals?
Rib cage moves, diaphragm contracts/flattens, thoracic volume increases.
What is the role of the diaphragm in ventilation?
Contracts to increase volume and decrease pressure.
What is the role of the external intercostal muscles in ventilation?
Lift ribs up and out during inhalation
What is the role of the internal intercostal muscles in ventilation?
Pull ribs down and in during forced exhalation
Define tidal volume.
Volume of air inhaled/exhaled per breath.
Define vital capacity
Maximum volume of air in one breath.
What is the breathing rate?
Number of breaths per minute.
What is oxygen uptake and how is it calculated?
tidal volume × breathing rate.
What is the structure of the gas exchange system in bony fish?
Mouth, buccal cavity, operculum, gills
How does ventilation occur in bony fish?
Buccal cavity floor lowers, water enters, mouth closes, operculum opens
