Respiratory system Flashcards
What is the exchange of gases between an organism and its environment (O2 & CO2) called?
Organismic respiration
What types of animals exchange gasses through simple diffusion?
Small aquatic organisms
How do complex multicellular organisms exchange gasses?
Specialized respiratory structures
What are examples of system adaptations to enhance gas exchange?
Amphibians respire across their skin as well as lungs, insects have an extensive tracheal system, fish use gills, and mammals have a large network of alveoli in lung tissue
How do animals with lungs exchange gasses?
They carry on ventilation by breathing air; respiratory and circulatory systems are functionally connected
What are the four main types of respiratory surfaces?
The animal’s own body surface, tracheal tubes, gills, and lungs
What do most respiratory structures have in common?
Most are supplied with blood vessels that facilitate exchange and transport of respiratory gases
Describe diffusion
Diffusion is passive, driven only by the difference in O2 and CO2 concentrations on the two sides of the membranes and their relative solubility in the plasma membrane
What is Fick’s law of diffusion?
The amount of a gas that diffuses across the alveolar membrane depends on differences in partial pressure, and on the surface area of the membrane; gas diffuses faster if the difference in pressure or the surface area increases
R = DA ∆p /d
What is Dalton’s law of partial pressures?
In a mixture of gases, total pressure of the mixture is the sum of the pressures of the individual gases
Each gas exerts, independently of the others, a partial pressure – the same pressure it would exert alone
Evolutionary changes have occurred to optimize the rate of ______
Diffusion (R).
How is the rate of diffusion optimized?
Increase surface area A, decrease distance d, or increase concentration difference Dp
What is ventilation (what most animals do)?
The active movement of air or water over respiratory surfaces
In what animals does gas exchange occur through the entire body surface?
Small animals with high surface area-to-volume ratios and low metabolic rates
In what kind of animals does the body secretes fluids that keep its surface moist?
Terrestrial animals
Describe tracheal tubes
Some arthropods have a network of tracheal tubes (tracheae) that delivers air directly to cells; Air enters through spiracles along body surface; muscles may help pump air in/out of spiracles
Describe gills
Moist, thin structures that extend from the body surface. The outer surface is exposed to water, inner side to networks of blood vessels
Describe dermal gills and what animals have them
Sea stars and sea urchins have dermal gills that project from the body wall – gases are exchanged between water and coelomic fluid
Describe the book lungs of spiders
They have thin plates of tissue filled with hemolymph, separated by air spaces that receive oxygen through a spiracle
How do lungs develop?
Lungs develop as ingrowths of the body surface or from the wall of a body cavity
What is homologous to lungs?
Swim bladders
Describe the gas exchange of amphibians
Most amphibians have lungs, although most of their gas exchange takes place across the body surface
Describe the gas exchange of reptiles
Reptiles draw air into the lungs, but gas exchange is not very efficient and does not sustain long periods of activity
What is the disadvantage of breathing air?
Respiratory surfaces must be kept moist because O2 and CO2 dissolve in fluid
What are the advantages of breathing air?
Air contains a higher concentration of oxygen, oxygen diffuses faster in air than water, and less energy is needed to move air over a gas exchange surface
Describe the countercurrent exchange system found in animals with gills
Blood flows in a direction opposite to the movement of the water, maximizing the difference in O2 concentration between blood and water along the area of contact
More than ____% of oxygen available in water diffuses into blood
80%
What do gill filaments contain?
A capillary network of blood vessels
Describe the location of gills
The gills form the lateral wall of the pharyngeal cavity, and they lie under a bony plate, the operculum.
Describe the function of gills
Each gill consists of a cartilaginous gill arch to which two rows of leaf-like gill laments attach. Each gill lament has many smaller extensions rich in capillaries. As water flows past the gill lament, oxygen passes from the water into blood circulating through the capillaries.
Describe theoretical concurrent flow in gills
If the system were concurrent—that is, if blood owed through the capillaries in the same direction as the flow of the water—much less of the oxygen dissolved in the water could diffuse into the blood.
What does a bird’s respiratory system consist of?
Paired lungs
Describe a bird’s respiratory system
The paired lungs contain static structures with surfaces for gas exchange, and connected air sacs, which expand and contract causing air to move through the static lungs.
How long does oxygen remain in the respiratory system of bird’s lungs?
A breath of oxygen-rich inhaled air remains in the respiratory system for two complete inhalation and exhalation cycles before it is fully spent (used) and exhaled out the body.
Why is the way birds breathe effective?
The unidirectional flow of fresh air over the gas exchange surfaces in the lungs. Furthermore, fresh air passes over the gas exchange surfaces during both inhalation and exhalation, resulting in a constant supply of fresh air enabling the bird to experience a near-continuous state of gas exchange within the lungs.
During vertebrate evolution, what changed?
The surface area of the lung increased
Mammalian lungs have millions of what?
Air sacs (alveoli) that increase the surface available for gas exchange
In mammals, what is surrounded by an extensive capillary network?
Alveoli in the lungs
In mammals, what does inhaled air pass through before the lungs?
Larynx, glottis, and trachea
Each mammalian lung is covered in what?
A pleural membrane, which forms a continuous sac that encloses the lung
Each alveolus is lined by what?
A single layer of epithelial cells through which gases diffuse into the surrounding capillaries
What does the bronchi in the lungs branch into?
Small bronchioles, each ending in a cluster of alveoli
Define ventilation
Mechanical process of moving air between the environment and the lungs
During inhalation/exhalation, the volume of the thoracic cavity is increased/decreased by what?
The movement of the diaphragm
How is the work of breathing reduced?
By pulmonary surfactant secreted by specialized epithelial cells the lining the alveoli
During inhalation, how does thoracic volume increase?
Through contraction of two muscle sets: contraction of the external intercostal muscles expands the rib cage and contraction of the diaphragm expands the volume of thorax and lungs
During inhalation, the contraction of the two muscles sets causes _____ pressure, which draws air into the lungs
negative
How does breathing rate increase?
Chemoreceptors in medulla are stimulated by increases in arterial CO2 concentration and signal to increasing breathing rate
