Respiration Chapter 35

Respiration Respiration is the exchange of gasses between an organism and its environment Gas exchange occurs between the environment and blood at the lungs, and the blood and cells at tissues For diffusion of gases to occur, all regions of exchange must be moist and thin. For animals, the expulsion of CO2 (created in the Krebs Cycle) and the introduction of O2 (for the ETC) is constantly necessary.

Respiration in Water Even if water is saturated with oxygen, it still contains a far smaller concentration than in air About 15-25% of energy in marine animals is used for respiration; only 1-2% in land animals Most aquatic animals have gills which are finely divided sections of vascular tissues Gills are extensions of the pharynx and covered in tissue called operculum Water enters the mouth to take in water, closing the operculum As the mouth closes, water is pushed through the operculum

Respiration in Water Each gill slit is made of filaments called lamellae Within each lamellae is a U-shaped vessel of blood. The blood and lamellae are surrounded by capillaries. As water flows through the gills, oxygen is extracted out through the capillaries and into the lamellae The capillaries bring in the oxygen through diffusion, so the fish doesn’t expend any energy in the process. However, the fish does have to take multiple more “breaths” than we do to absorb the same quantity of oxygen as air-breathing organisms

Respiration Organs Trachea A trachea is the air tube leading from the environment to the lungs Lungs Large sacs for storing and exchanging gasses Lungs rely on a constant vacuum for drawing gasses in and expelling them out The pumping of lungs is controlled by a diaphragm in mammals, a flat muscle that constricts and contracts

Human Respiratory System The primary organ for drawing in oxygen for humans is the nose. The mouth is the backup. Air from either organ reaches the pharynx. Instead of travelling down the esophagus, as food does, air travels into the larynx. Inside the larynx are thin, membranous tissues called vocal cords. Vocal cords are used when air passes back up the trachea during expulsion of air, creating sound waves The larynx then leads into the trachea. The trachea is surrounded by rings or cartilage to ensure the tube does not collapse.

Human Respiratory System The trachea divides into two tubes called bronchi. Bronchi lead air into the right and left lungs Once inside the lungs, the bronchi separate a second time to form bronchioles Bronchioles are thinner than the bronchi and trachea and do not have any cartilage. Each bronchiole ends in an elongated space filled with air pockets called alveoli Alveoli is the site of gas exchange

Human Ventilation When the diaphragm muscles contract, they pull the diaphragm down and raise the ribcage Like blowing up a balloon, this pulls air into the lungs through the respiratory organs When the muscle relaxes, the pressure in the lungs decreases and the extra air is forced back out. Blood travels along these muscles where cells monitor the O2 and CO2 levels of the blood. These cells send messages to the brain’s medulla oblongata, which controls the rate of contraction and relaxation of the diaphragm.

Human Gas Exchange Gas exchange is mainly through diffusion and, thus, not controlled by the organism Blood flowing into the capillaries in the alveoli contains a higher CO2 concentration than the atmospheric air. Air flowing into the capillaries has a higher O2 concentration than the blood. O2 and CO2 will flow across the membrane until the concentrations on either side are closer to equilibrium.

Human Gas Exchange Red blood cells contain hemoglobin, which chemically attracts oxygen. Oxygen is directly carried by red blood cells. Most of the CO2 however travels in the plasma as either carbon monoxide or HCO3-. The hemoglobin rearranges the molecules into carbon dioxide in the lungs and expels the remaining CO2.

Respiration and Health The upper respiratory tract includes the nose, pharynx and larynx. Strep throat is an upper respiratory infection caused by Streptococcus p. bacteria The result is sore throat and fever Sinusitis: blockage of the sinuses that leads to soreness and headache Laryngitis: infection of the larynx leading to an inability to talk Tosilitis: inflammed tonsils, leading to swelling and/or inability to breathe effectively.

Respiration and Health The lower respiratory system consists of the bronchi through the alveoli Bronchitis Inflammation of the bronchi due to multiple infections. Pneumonia Infection of the lungs from multiple bacterial, viral, or fungal parasites Pneumonia causes the alveoli and bronchioles to fill with a thick liquid, preventing gas exchange Tuberculosis An infection of the bacteria Bacillus, causing breakdown of alveoli

Respiration and Health Asthma Asthmatic lungs are overly sensitive to irritants, which cause spasms The spasms can also cause long-term inflammation damage. Lung Cancer Lung cancer is the result of damaged tissue in the alveoli or bronchioles Lung cancer kills cilia in the cells, preventing foreign contaminants from being expelled out of the lungs The contaminants cause further infections until tumors occur.