2+Respiration

**THE RESPIRATORY SYSTEM**
Day One presentation:

Day Two:

IB syllabus:

Gas exchange:
 * 6.4.1: Distinguish between ventilation, gas exchange, and cell respiration.
 * 6.4.2: Explain the need for a ventilation system.
 * 6.4.3: Describe the features of the alveoli that adapt them to gas exchange.
 * 6.4.4: Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles, and alveoli.
 * 6.4.5: Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and abdominal muscles.

//6.4.1: Distinguish between ventilation, gas exchange, and cell respiration.// > Cell respiration (recall plant chapter) > > Occurs in the cytoplasm and the mitochondria. > > Releases energy in the form of ATP. > Gas exchange > > Swapping of gases. > > Oxygen in, CO2 out. > > Occurs in alveoli in the lungs. > > Oxygen diffusion: from air in alveoli to blood in capillaries. > > CO2 diffusion: opposite direction of oxygen, capillaries to alveoli. > > Reason for diffusion: concentration gradients of oxygen and CO2 between air and blood are different. > Ventilation > > Maintains the concentration gradient (6.4.2). > > Air in the alveoli must be refreshed frequently.

//6.4.3: Describe the features of the alveoli that adapt them to gas exchange.//

Gas exchange occurs in the alveoli. > Surface area > > Alveolus is very small; millions of them in total. > > Results in large surface area. > Alveolus wall > > Consists of a single layer of very thin cells. > Capillary wall > > Also single layer of very thin cells. > > Gases only need to diffuse very short distance. > Covered by a dense network of blood capillaries with low oxygen and high CO2 concentrations. > > Due to that, oxygen diffuses into the blood, while CO2 diffuses out (concentration gradient). > Secretion of fluid in alveolus wall > > Keeps inner surfaces of alveolus moist. > > Allows gases to dissolve. > > Fluid contains natural detergent, preventing the sides of the alveolus from sticking together.

//6.4.4: Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles, and alveoli.//




 * Nasal cavity – nose; takes in/releases air
 * Pharynx – area in vertebrate throat where air and food passages cross
 * Larynx – voicebox; containing the vocal cords
 * Trachea – windpipe; airway extending from larynx to primary bronchi
 * Lungs – invaginated respiratory surface that connects to atmosphere via narrow tubes
 * Bronchus – breathing tube branching from trachea into lungs
 * Diaphragm – sheet of muscle forming the bottom wall of thoracic cavity in mammals; active in ventilating lungs
 * Bronchiole – fine branch of bronchus transporting air to alveoli
 * Alveoli – tiny air sacs at end of each bronchiole
 * Capillary –microscopic blood vessel; allows exchange between blood and interstitial fluid.

//6.4.5: Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and abdominal muscles.//

> To inhale, the diaphragm contracts and flattens and the external intercoastal muscles also contract and cause the ribcage to expand and move up. The diaphragm contracts drops downwards. Thoracic volume increases, lungs expand, and the pressure inside the lungs decreases, so that air flows into the lungs in response to the pressure gradient. > These movements cause the chest cavity to become larger and the pressure to be smaller, so air rushes in from the atmosphere to the lungs. > To exhale, the diaphragm relaxes and moves up. In quiet breathing, the external intercoastal muscles relax causing the elasticity of the lung tissue to recoil. > In forced breathing, the internal inercoastal muscles and abdominal muscles also contract to increase the force of the expiration. > Thoracic volume decreases and the pressure inside the lungs increases. Air flows passively out of the lungs in response to the pressure gradient. The ribs to move downward and backward causing the chest cavity to become smaller in volume and the pressure increases pushing air out of the lungs into the atmosphere. (From __AP Edition Biology__)

//Functions of respiratory system//


 * Providing an area for gas exchange between air and circulating blood
 * Moving air to and from exchange surfaces
 * Protecting respiratory surfaces from environmental variations
 * Producing sounds
 * Providing olfactory sensations

//Organization of the respiratory system//


 * Includes the nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli
 * Respiratory tract: carries air to and from alveoli
 * Upper respiratory system: filters and humidifies incoming air
 * Lower respiratory system: gas exchange

//The Basics//




 * Respiratory Medium: source of O2
 * Air or and water
 * Respiratory Surface: where gases are exchanged with the surrounding environment
 * Animals move O2 and CO2 by passive transport (diffusion-higher concentration to lower concentration)
 * Rate of diffusion = proportional to the surface area where diffusion occurs and inversely proportional to the square of the distance of movement
 * Thin and large surface area, maximize gas exchange

//Mammalian respiration//


 * Negative pressure breathing: pulling air instead of pushing it out into the lungs.
 * Lung volume increases as rib muscles and diaphragm contract
 * Tidal volume: Volume of air inhalation
 * Vital capacity: Max t.v. in forced breathing
 * Residual volume: amount of air remaining after forced breathing



//Non-Mammalian respiration//

> Outfoldings of body surface extended in water > Helps ventilation process: increasing flow of respiratory medium over the respiratory surface > Countercurrent exchange: makes it possible to transfer O2 to the blood > As blood moves through gill capillaries, loaded with O2, even through against concentration gradient > More than 80% in O2 in water is able to be diffused > Tracheal system: air tubes branching through body > Folded internal respiratory surface > Trachae – opens outside > Open circulatory system > 8 or 9 airsacs and lungs > Bellows keeping air flowing > Not to be confused with alveolar sacs > Positive pressure breathing: air is forced through lungs > During cycle, muscles lower in oral cavity, drawing air through nostrils > Closed nostrils and mouth, floor of oral cavity rises > Air is forced down trachea > Elastic recoil of lungs and compression of muscular body wall force air back out of the lungs
 * G=lls
 * Insects
 * Birds
 * Amphibians

//Breating ventilates the lungs//

> Breathing control centers: medulla oblongata and pons. > Pons sets basic breathing rhythm. > Sensors in aorta and carotid arteries monitor O2 and CO2 concentrations > Negative-feedback mechanism prevents lungs from over-expanding. > Medulla regulates breathing activity in response to pH changes of tissue fluid.
 * Control of breathing

//Pressure and Ventilation//

> Low when you are relaxed and breathing quietly > Drops when you inhale > Increases when you exhale > Partial Pressure: A measure of the concentration of one gas in a mixture of gases; pressure exerted by particular gas in a mixture of gases (pressure exerted by oxygen in air)
 * The direction of airflow is determined by the relation of atmospheric pressure and intrapulmonary pressure
 * Intrapulmonary Pressure is the pressure inside the alveoli
 * Respiratory Pressure
 * Atmospheric pressure decreases with increasing altitude and so do the partial pressure of gases including oxygen

//Gas exchange at high altitude//

> Hemoglobin may not become fully saturated as it passes through the lungs tissues of the body may not be adequately supplied with oxygen > Mountain Sickness: with muscular weakness, rapid pulse, nausea and headaches can be avoided by ascending gradually to allow the body to acclimatize to high altitude > Extra red blood cells are produced, increasing the hemoglobin content of the blood > Muscles produce more myoglobin and develop a denser capillary network > Some people who are native to high altitude show other adaptations:
 * Partial air pressure of oxygen at high altitude is lower than at sea level
 * Effects
 * During acclimatization the ventilation rate increases
 * These changes help to supply the body with enough oxygen
 * 1) a high lung capacity with a large surface area for gas exchange
 * 2) larger tidal volumes and hemoglobin with an increased affinity for oxygen

//Changes in the respiratory system//

> Before delivery, fetal lungs are fluid-filled and collapsed. > At first breath, lungs inflate and never collapse completely thereafter. > Less efficient in elderly > Elastic tissue deteriorates, lowering the vital capacity of the lungs. > Movements of the chest are restricted by arthritic changes and decreased flexibility of costal cartilages. > Some degree of emphysema is generally present.
 * At birth
 * Aging:





//Study Questions://


 * 1) Why is the position of lung tissues within the body an advantage for terrestrial animals?
 * 2) Explain how countercurrent exchange maximizes the ability of fish gills to extract dissolved O2 from water
 * 3) How does an increase in the CO2 concentration in the blood affect the pH of cerebrospinal fluid?
 * 4) A slight decrease in blood pH causes the heart’s pacemaker to speed up. What is the function of this control mechanism?
 * 5) How does breathing differ in mammals and birds?
 * 6) What determines whether O2 or CO2 diffuse into or out of the capillaries in the tissues and near the alveolar spaces? Explain.
 * 7) How does the Bohr shift help deliver O2 to very active tissues?
 * 8) Carbon dioxide within red blood cells in the tissue capillaries combines with water, forming carbonic acid. What causes the reverse of this reaction in red blood cells in capillaries near the alveolar spaces?
 * 9) Describe three (3) adaptations that enable Weddell seals to stay underwater much longer than humans can.

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