respiratory system Flashcards
why do we need O2?
we need to get O2 into the body, transport the molecules to the cells where O2 serves as the final electron acceptor in the electron transport chain.
what is ventilation and how can it occur?
the exchange of respiratory gases between the organism and the environment. Ventilation usually involves a specialized organ, such as lungs, gills, or similar structure. However, any surface that has a thin and moist epithelium can serve as a respiratory membrane. Moisture is required because the gases need to be in solution, and a thin epithelium, usually a simple epithelium, allows for rapid diffusion into a blood supply, which allow the O2 to be distributed throughout the body.
what is O2 concentration in water and air? warm water cold water? fresh or salt?
Water can hold much less O2 than air. For example, well oxygenated water has about a 0.7% concentration (0.8% in cool freshwater) of O2. We usually generalize and indicate that its maximum concentration of O2 is about 1%. In contrast, air at sea level has approximately 21% O2 concentration (with most of air consisting of N2 = 78-79%). We usually indicate that a given volume of air has about 20X more O2 available than the same volume of water. Also, as water warms, less O2 is present. Also, as solutes increase, water can hold less O2 in solution; thus, saltwater has less O2 than freshwater.
Major respiratory surfaces or organs of invertebrates include: what are the five common types and a little about them?
1) “skin” = body surface. This is referred to as cutaneous or transcutaneous respiration, such as in sponges, cnidarians, flatworms.
2) Gills, in annelids, mollusks, starfish, arthropods + many thin projections that increase surface area.
3) Book Lung: some spiders, scorpions. These consist of many thin plates that have a rich blood supply. The book lungs are kept in a pouch in the body.
4) Lungs: snails, some spiders, some insects. An internal pouch with a respiratory lining.
5) Tracheole system. Insects. System of tubes, called tracheae. These are highly branched and very efficient. The small tubes take O2 directly to cells without entering the blood stream. Openings to the tubes on the outer surface of the body are called Spiracles.
gill structures of advanced fish: describe them and what happens when fish taken out of water?
The gill arch is the skeleton of the gill, and the filaments that extend off of the arch are soft tissue with a good blood supply. The filaments are formed from primary lamellae and secondary lamellae. In particular, the secondary lamellae greatly increase the surface area for maximal oxygen uptake. Notice that the water flows across the secondary lamellae. Fish will suffocate when plucked out of water because the secondary lamellae collapse onto each other, greatly decreasing the surface area. why they suffocate in air that has significantly more oxygen available to them than in water.
types of ventilation: lungfish and frog example?
lungfish gulp air into their oral cavity and force it into their lungs (a force pump mechanism). Frogs, have simple, sac-like lungs with relatively little surface area for gas exchange. Many frogs can also obtain oxygen through their skin, which must be kept moist. They use a force pump mechanism to force air from the oral cavity into their lungs.
types of ventilation: bird example?
Birds increase the efficiency of their respiratory system by adding an extensive series of air sacs, which serve as reservoirs of air during inhalation. Birds have a rue circulation of air through their parabronchi and air capillaries (no dead air space) and they require two inhalations and two exhalations to completely move air through their respiratory system. About 75% of the air bypasses the lungs and the structures where oxygen is extracted form air (air capillaries off of parabronchi). During flight, beating of the wings help regulate ventilation rate.
types of ventilation: mammal lungs?
resembling a slice of a kitchen sponge. Gas exchange occurs in small sacs at the ends of a series of respiratory tubes. Each small sac is an alveolus (the plural for alveolus is alveoli). Each alveolus is surrounded by a capillary bed, which serves as the site of gas exchange between the alveolus and the bloodstream. Mammals rely on negative pressure to suck air into their lungs. This is accomplished in part by expansion of the thoracic cage (rib cage) and movement of a diaphragm. Millions of alveoli are present in each of your lungs. The overall surface area of the alveoli is about 50X that of the surface area of your skin.
what is the coordination of breathing in a mammal?
Normally, breathing is involuntary and automatic, regulated by centers in the medulla oblongata of the brain. Deep breathing is regulated by CO2 levels in the blood. This is due to CO2 effects on blood pH as it affects H+ concentration.
how are gases transported in the blood?
Exchange of CO2 and O2 in alveoli actually occurs due to a concentration gradient that exists—simple diffusion is responsible for the exchange. However, after O2 enters the blood stream, it needs to be transported, usually with a carrier molecule. O2 does not dissolve well in water (remember at best water can be 1% saturated with O2). Only about 1% to 5% of the O2 required by a human can be carried dissolved in plasma. Typically, O2 is carried by protein, hemoglobin (Hb), in the red blood cells (RBC or erythrocytes), of vertebrates. Each RBC in your body has about 250 million Hb molecules, and each Hb molecule can carry four O2 molecules. Hb has an unusual and vital property—it takes up O2 when it is in high concentration (as in alveoli), and release O2 when in an area of low concentration (as in active cells). decrease in pH will cause HB to release more O2 (Bohr Effect)—such as occurs in active cells where anaerobic respiration results in glycolysis causing a buildup of lactic acid and CO2 increase. An increase in temperature will also cause the oxygen hemoglobin dissociation curve to shift to the right. CO2 is carried in the blood and affects respiratory rate.
how is CO2 carried in three forms?
1) Dissolved in Plasma and RBC as CO2 (7-8%); 2) Carried by Hb (exchanged with O2 in alveoli) (23-25), and 3) Carried as bicarbonate (67 – 70%). CO2 can be converted to the a bicarbonate ion and a hydrogen ion. This occurs in a reversible reaction that involves H2O and the enzyme carbonic hydrogenase.
CO2 + H20 <–>H2CO3 <–> HCO3- + H+
In the formula above, carbonic anhydrase, is used to reversibly change CO2 and H20 into carbonic acid (H2CO3). Carbonic acid can then dissociate into the bicarbonate ion (HCO3- ) and a hydrogen ion (H+). Sensors along the bloodstream actually monitor the hydrogen ion concentration (pH), rather than oxygen levels, to regulate breathing depth and rate.
