Respiratory System PDF

# Focus on Homeostasis ## Contributions of the Respiratory System **For All Body Systems** * Provides oxygen and removes carbon dioxide * Helps adjust pH of body fluids through exhalation of carbon dioxide ## Systems and their role in Homeostasis | System | Role in Homeostasis | |---|---| | Mus...

# Focus on Homeostasis ## Contributions of the Respiratory System **For All Body Systems** * Provides oxygen and removes carbon dioxide * Helps adjust pH of body fluids through exhalation of carbon dioxide ## Systems and their role in Homeostasis | System | Role in Homeostasis | |---|---| | Muscular System | Increased rate and depth of breathing supports increased activity of skeletal muscles during exercise | | Nervous System | Nose contains receptors for sense of smell, Vibrations of air flowing across vocal folds produce sounds for speech | | Endocrine System | Angiotensin-converting enzyme (ACE) in lungs catalyzes formation of the hormone angiotensin I from angiotensin | | Cardiovascular System | During inhalation, venous blood to the heart | | Lymphatic System and Immunity | Hairs in nose, cilia and mucus in trachea, bronchi, and smaller airways, and alveolar macrophages contribute to nonspecific resistance to disease, Pharynx (throat) contains lymphatic tissue (tonsils), Respiratory pump (during inhalation) promotes flow of lymph | | Digestive System | Forceful contraction of respiratory muscles can aid in defecation | | Urinary System | Together, respiratory and urinary systems regulate pH of body fluids | | Reproductive System | Increased rate and depth of breathing, Internal respiration provides oxygen to support activity during sexual intercourse | ## Disorders: Homeostatic Imbalances * Asthma * Chronic obstructive pulmonary disease * Lung Cancer * Pneumonia * Tuberculosis * Common cold * Pulmonary edema * Cystic fibrosis * Asbestos-related diseases * Sudden infant death syndrome * Acute respiratory distress ## Aging and the Respiratory System Aging results in decreased: * Vital capacity * Blood O₂ level * Alveolar macrophage activity * Ciliary action of respiratory epithelia Consequently, elderly people are more susceptible to pneumonia, bronchitis, emphysema, and other issues ## Exercise and the Respiratory System The respiratory and cardiovascular systems make adjustments in response to both the intensity and duration of exercise * As cardiac output rises, the blood flow to the lungs, termed pulmonary perfusion, increases as well * The O₂diffusing capacity may increase threefold during maximal exercise so there is a greater surface area available for O₂diffusion ## Summary of Stimuli that Affect Breathing Rate and Depth | Stimuli that Increase Breathing Rate and Depth | Stimuli that Decrease Breathing Rate and Depth| |---|---| | Voluntary hyperventilation, Increase in arterial blood PCO₂ above 40 mmHg, Increased activity of proprioceptors, increase in body temperature | Voluntary hypoventilation, Decrease in arterial blood PCO₂ below 40 mmHg, Decrease in arterial blood PO₂ from 105 mmHg to 50 mmHg, Decreased activity of proprioceptors, Decrease in body temperature (decreases respiration rate), Sudden cold stimulus (causes apnea), Severe pain (causes apnea), Increase in blood pressure, Irritation of pharynx or larynx by touch or chemicals (causes brief apnea followed by coughing or sneezing)| ## Control of Respiration * **Hypercapnia** * A slight increase in PCO₂ (and thus H⁺) * Stimulates central chemoreceptors * **Hypoxia** * Oxygen deficiency at the tissue level * Caused by a low PO₂ in arterial blood due to high altitude, airway obstruction or fluid in the lungs * **Cortical influences** * Allow conscious control of respiration that may be needed to avoid inhaling noxious gasses or water * **Chemoreceptor** * Central and peripheral chemoreceptors monitor levels of O₂ and CO₂ and provide input to the respiratory center ## Transport of O₂ and CO₂ in the Blood * **Oxygen** * 1.5% of the O₂ is dissolved in the plasma * 98.5% of the O₂ is carried by hemoglobin (Hb) * **Carbon dioxide** * 7% of the CO₂ is dissolved in the plasma * 23% of the CO₂ is carried by Hb inside red blood cells as carbaminohemoglobin * 70% of the CO₂ is transported as bicarbonate ions (CO₃^-) ## External and Internal Respiration * **External Respiration**: Oxygen diffuses from the alveoli into the pulmonary capillaries, CO₂ moves in the opposite direction * **Internal Respiration**: Oxygen diffuses from the systemic capillaries into the tissue, CO₂ moves in the opposite direction ## Exchange of Oxygen and Carbon Dioxide During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli. ## Modified Breathing Movements | Movement | Description | |---|---| | Coughing | A long-drawn and deep inhalation followed by a complete closure of the rima glottidis, which results in a strong exhalation that suddenly pushes the rima glottidis open and sends a blast of air through the upper respiratory passages. Stimulus for this reflex act may be a foreign body lodged in the larynx, trachea, or epiglottis. | | Sneezing | Spasmodic contraction of muscles of exhalation that forcefully expels air through the nose and mouth. Stimulus may be an irritation of the nasal mucosa | | Sighing | A long-drawn and deep inhalation immediately followed by a shorter but forceful exhalation.| | Yawning | A deep inhalation through the widely opened mouth producing an exaggerated depression of the mandible. It may be stimulated by drowsiness, or someone else's yawning, but the precise cause is unknown| | Sobbing | A series of convulsive inhalations followed by a single prolonged exhalation. The rima glottidis closes earlier than normal after each inhalation so only a little air enters the lungs with each inhalation| | Crying | An inhalation followed by many short convulsive exhalations, during which the rima glottidis remains open and the vocal folds vibrate; accompanied by characteristic facial expressions and tears| | Laughing | The same basic movements as crying, but the rhythm of the movements and the facial expressions usually differ from those of crying. Laughing and crying are sometimes indistinguishable| | Hiccupping | Spasmodic contraction of the diaphragm followed by a spasmodic closure of the rima glottidis, which produces a sharp sound on inhalation. Stimulus is usually irritation of the sensory nerve endings of the gastrointestinal tract| | Valsalva maneuver| Forced exhalation against a closed rima glottidis as may occur during periods of straining while defecating| | Idle ear| The nose and mouth are held closed and air from the lungs is forced through the auditory tube into the middle ear. Employed by those snorkeling or scuba diving during descent to equalize the pressure of the middle ear with that of the external environment| ## Breathing Patterns and Respiratory Movements * Eupnea * Apnea * Dyspnea * Tachypnea * Costal breathing * Diaphragmatic breathing ## Boyle's Law * The volume of a gas varies inversely with its pressure ## Pulmonary Ventilation In pulmonary ventilation, air flows between the atmosphere and the alveoli of the lungs because of alternating pressure differences created by contraction and relaxation of respiratory muscles * **Inhalation**: Diaphragm contracts pushing downward, Lungs expand as pressure inside decreases, Air flows in through nose and mouth * **Exhalation**: Diaphragm relaxes pushing upward, Lungs made smaller and more pressurized by relaxing diaphragm, Air passes out through nose and mouth ## Blood Supply to the Lungs * Blood enters the lungs via the pulmonary arteries (pulmonary circulation) and the bronchial arteries (systemic circulation) * Blood exits the lungs via the pulmonary veins and the bronchial veins * **Ventilation-perfusion coupling:** Vasoconstriction in response to hypoxia diverts blood from poorly ventilated areas to well ventilated areas ## Respiratory Membrane The respiratory membrane is composed of: 1. A layer of type I and type II alveolar cells and associated alveolar macrophages that constitutes the alveolar wall 2. An epithelial basement membrane underlying the alveolar wall 3. A capillary basement membrane that is often fused to the epithelial basement membrane 4. The capillary endothelium ## Alveolus * There are 2 kinds of alveolar cells, Type I and Type II ## Alveoli in a Lobule of a Lung Alveoli are sac-like structures ## Alveoli * When the conducting zone ends at the terminal bronchioles, the respiratory zone begins * The respiratory zone terminates at the alveoli, the "air sacs" located within the lungs ## Lungs * The lungs are enclosed and protected by the pleural membrane * The lungs are paired organs in the thoracic cavity ## Bronchi At the superior border of the 5th thoracic vertebrae, the trachea branches into a right primary bronchus which enters the right lung and a left primary bronchus which enters the left lung ## Trachea The trachea extends from the larynx to the primary bronchi ## Larynx * The larynx contains vocal folds, which produce sound when they vibrate * The larynx (voice box) is a passageway that connects the pharynx and trachea ## Pharynx The pharynx functions as a passageway for air and food, provides a resonating chamber for speech sounds, and houses the tonsils, which participate in immunological reactions against foreign invaders ## Surface Anatomy of the Nose 1. **Root**: Superior attachment of the nose to the frontal bone 2. **Apex**: Tip of nose 3. **Bridge**: Bony framework of nose formed by nasal bones 4. **External naris**: Nostril; external opening into nasal cavity