The Human Respiratory System GAS EXCHANGE The Human Respiratory System

Are the human lungs identical? No, the right lung is shorter than the left by 1 inch; however, its total capacity is greater. The right lung has three lobes, the left lung has two. The maximum capacity of the lung averages about 6,500 cubic centimeters (cc) or 1.7 gallons (6.4 liters). A. Respiration - has two definitions 1) The release of energy from nutrients 2) The Gas Exchange of Oxygen and Carbon Dioxide between the organism and the environment.

Respiratory Surface Requirements: 1) surface must be thin walled so that diffusion across it can occur rapidly 2) surface must be moist because the Oxygen and Carbon-Dioxide must be in a solution 3) surface must be in contact with a source of Oxygen that exists in the surroundings 4) surface must be in contact w/ the transport system that carries dissolved materials to & from the cells of the organism

a) SKIN is respiratory surface which must be kept moist for oxygen to dissolve in & diffuse across the skin b) skin secretes mucus which facilitates the diffusion of gases into & out of blood c) hemoglobin- respiratory pigment proteins in blood that increases oxygen & carbon dioxide carrying capacity

Human Respiratory System a) alveoli (respiratory surface) in the lungs are thin, moist, internal gas exchange surface b) hemoglobin aids in the transport of oxygen THE FLOW OF AIR Nasal Cavity The nasal cavity is exposed to the air through the nostrils which is lined with a ciliated mucous membrane which filters, warms, and moistens the air.

Pharynx The pharynx is the area in which the oral cavity & nasal cavity meet. Food is prevented from entering the trachea by the epiglottis  Trachea The trachea is kept open by rings of cartilage. The ciliated mucous membrane which lines the trachea traps microscopic particles & sweeps them toward the bronchi. Deposits from cigarette smoke & other atmospheric pollutants may interfere with the action of cilia.

 Bronchi The 2 major subdivisions of the trachea are the bronchi. The bronchi are lined with mucous membrane & ringed with cartilage. Each bronchus extends into a lung where it subdivides many times forming progressively smaller bronchioles. Bronchioles Bronchioles are lined with mucous membrane but lack cartilage rings and no cilia present. Tiny bronchioles terminate with the alveoli.

Alveoli Alveoli are the functional units for gas exchange. They are thin, moist, & surrounded by capillaries. In humans, oxyhemoglobin is in highest concentration in the capillaries of alveoli. Lung Each bronchus with its bronchioles and alveoli is called a lung.

PHASES of HUMAN RESPIRATION 1. Breathing: bringing air into & out of lungs (2 PHASES)  Inhalation (inspiration)- 1. diaphragm pulled down Active phase 2. ribs pulled up & out 3. (-) pressure causes air to fill lungs

Exhalation (expiration)- 1. diaphragm relaxes, comes up Passive phase 2. ribs relax, drop down & in 3. (+) pressure forces air out of lungs Breathing rate is affected by carbon dioxide level (NOT the AMOUNT of OXYGEN) in blood & its affect on the respiratory center of the brain. Also, the acidity of the blood (caused by lactic acid) stimulates the respiratory center.

2. External Respiration: exchange of gases between air & blood in the alveoli 3. Circulation: bringing respiratory gases to different parts of body 4. Internal Respiration exchange of oxygen for carbon dioxide between blood & body cells

DISEASES of RESPIRATORY SYSTEM 1. Asthma - severe allergic reaction that constricts bronchioles 2. Bronchitis- inflammation of bronchial tubes 3. Emphysema - lungs lose elasticity, shortness of breath 4. Pneumonia- fluid in alveoli 5. Lung Cancer - tumors form in lungs * Smokers are at greater risk for # 2, 3, & 5 *

2. Why does the human voice sound so strange after breathing helium? Since the speed of sound in helium is nearly three times the speed of sound in air, the pitch of the human voice becomes correspondingly higher.