HBIO301 Ch. 22
What are the primary functions of the respiratory system?
1. External respiration (gas exchange between air and blood) 2. Pulmonary ventilation (tidal movement of air into and out of lungs) 3. Protect Respiratory surfaces from dehydration, temperature changes and pathogens 4. Internal respiration 5. Produce Sound (communication) 6. Provide Olfactory sensation (smell)
Be able to trace air flow from the external nares (nostril) to the alveolar sacs and identify structures in the upper and lower respiratory systems
(nose, nasal cavity, paranasal sinus, pharynx) upper respiratory system (larynx, trachea, bronchi, bronchioles, lungs, and alveoli) lower respiratory system
Know which portions of the respiratory system are "conducting" and in which structures gas exchange is possible
- Conducting portion: from nasal cavity to terminal bronchioles - Respiratory portion: respiratory bronchioles & alveoli >> Site of gas exchange
What mechanisms defend the delicate respiratory epithelium from particulate matter and pathogens?
-goblet cells and underlying lamina propria which contain mucus and serous glands -mucus traps particles and the serous gland secretes digestive enzymes to destroy pathogens -cilia move contaminated mucus posteriorly to the pharynx to be swallowed and eventually digested in the stomach
What structures are involved in sound production? What is phonation and articulation?
-larynx (vocal ligaments of vocal cords and glottis) -air passing through the glottis vibrates vocal folds and produces sound waves -phonation- sound production at the larynx -articulation- modification of sound by other structures - tongue, lips, teeth, cheeks, plus resonance and amplification by the pharynx, oral and nasal cavities, and sinuses
As specifically mentioned in lecture (see slide 8), where are pneumatic bones found (those that contain sinuses), during what developmental age are the sinuses formed and what is their function?
-pneumatic bones found only in the skull -ethmoid sinus- present at birth -maxillary sinus- present at birth -frontal sinus- develops at around age 7 -sphenoid sinus- develops at adolescence -function of sinuses are to reduce facial skull weight, provide buffer against facial trauma, insulate dental roots and eyes to rapid temperature changes, and involvement in immunological defenses
Be able to describe the physical principles that govern the movement of air into and out of the lungs as well as those that are responsible for the diffusion of gases into and out of the blood. What is the difference between intrapulmonary and intrapleural pressure? What happens if intrapleural pressure becomes positive?
-pulmonary ventilation- physical movement of air into and out of the respiratory tract; changes in pleural volume changes pressure resulting in air flow -Inhalation- elevation of the rib cage and contraction of the diaphragm increase the size of the thoracic cavity. Pressure within the thoracic cavity decreases, and air flows into the lungs -Exhalation- when the rib cage returns to its original position and the diaphragm relaxes, the volume of the thoracic cavity decreases. Pressure rises, and air moves out the lungs -Boyles Law (P=1/V)- pressure of a gas in a closed container at constant temperature is inversely proportional to the volume Intrapulmonary pressure -relaxed breathing (eupnea): difference between atmospheric pressure and intrapulmonary pressure is typically small -forced breathing (hyperapnea): can increase range from -30mm Hg for inspiration to +100 mm Hg expiration Intrapleural pressure -pressure in space between parietal and visceral pleura -remains below Patm throughout respiratory cycle due to elastic fibers pulling lungs away from body wall If intrapleural pressure becomes positive--> causes pneumothorax- an abnormal accumulation of air in the pleural space --> breaks the seal created by the pleural fluid and lung collapses
Be familiar with the anatomical differences between the right and left lung and the anatomy of the bronchial tree, bronchioles, pulmonary lobules and alveolar sacs as well as the regulatory mechanisms that govern air and blood flow to the respiratory exchange surfaces
-right and left primary bronchi Right primary bronchi- larger in diameter, descends at a steeper angle STUDY SLIDE 26 FOR SPECIFIC LEFT AND RIGHT LUNG DIFFERENCES Left Lung -has a superior lobe (4 bronchopulmonary segments) -has an inferior lobe (5 bronchopulmonary segments) Right Lung -has a superior lobe ( 3 bronchopulmonary segments) -has a MIDDLE LOBE (2 bronchopulmonary segments) -has an inferior lobe (5 bronchopulmoary lobes) Bronchial Tree Anatomy (biggest to smallest structure) -trachea --> left or right bronchus--> secondary bronchus--> tertiary bronchi--> smaller bronchi--> bronchioles--> terminal bronchiole--> respiratory bronchiole--> alveoli in a pulmonary lobule -supportive connective tissue changes ( C-shaped rings replaced by cartilage plates) -epithelium changes (initially pseudostratified ciliated columnar, replaced by simple columnar, then simple cubodial epithelium) -Smooth muscles: >> Widen airways with sympathetic stimulation (bronchodilation) ->> Constricts under parasympathetic direction (bronchoconstriction) Bronchioles - each tertiary bronchus branches into multiple bronchioles, which branch into terminal bronchioles (~6500) -have no cartilage (smooth muscle) Alveoli - exchange surfaces within the lobule Aveoulus -connected to alveoli along alveolar ducts -alveolar ducts end at alveolar sac -extensive network of capillaries -surrounded by elastic fibers -alveolar pores allow for equalization of air pressure among alveoli Gas and Blood supply - Each lobule receives a pulmonary arteriole and a network of capillaries that surround each alveolus - BP in pulmonary circuit is low - Pulmonary vessels are easily blocked by blood clots, fats, or air bubbles causing pulmonary embolism - Blood flow through the pulmonary capillaries is slow and sheet like - Diffusion occurs rapidly across the respiratory membrane because distance is short and gases are lipid soluble
What are the three types of cells that make up the alveolar epithelium? Which is responsible for modifying the surface tension? How and why is this important? What happens when there is insufficient surfactant?
1. pneumocytes type 1 (type 1 alveolar cell)- unusually thin and delicate 2. alveolar macrophages (dust cells)- phagocytize particles 3. pneumocytes type ii (septal cells)- produce surfactant, an oily secretion containing phospholipids and proteins; function is to reduce surface tension and helps keep the passageways to alveoli open. pneumocytes type ii (septal cells) modify the surface tension
Where are the tonsils located, what are their general functions?
3 types of tonsils (all in the pharynx) In the Nasopharynx: 1. pharyngeal tonsil- located posterior wall, destroys entering pathogens In the Oropharynx: 1. palatine tonsils- lateral walls of the fauces (tonsillectomy) 2. Lingual tonsils - cover posterior surface of tongue
What muscles are involved in quiet breathing (eupnea) versus forced/active breathing (hyperpnea) during both inspiration and expiration?
Eupnea (During Inhalation) 1. Diaphragm - contraction draws air into the lungs >> 75% of normal air movement 2. External intercostal muscles- assist inhalation; 25% normal 3. Accessory muscles assist in elevating ribs: Sternocleidomastoid, Serratus anterior, Pectoralis minor and Scalene muscles Hyperanea (During Exhalation) 1. Interal intercostal and transversus thoracic - depresses rib 2. abdominal muscles- compress the abdomen and force the diaphragm upward
What are the steps that are involved in external respiration vs. internal (cellular) respiration?
Internal or Cellular Respiration- involves the uptake of oxygen and the formation of h20 within individual cells External respiration- includes all processes involved in exchanging oxygen and co2 with the environment including: -pulmonary ventilation -gas diffusion across membranes and capillaries -transport of oxygen and co2 between alveolar capillaries and capillary bed in other tissues External respiration brings in O2 for internal respiration and internal respiration gives the CO2 waste for the external respiration to take it out the body (exhaling)
Be familiar with the neuronal mechanisms for regulating respiration, including the central role of the ventral respiratory group (VRG) in generating respiratory rhythm and the modulatory effect of dorsal (DRG) through integration of chemoreceptor input.
Pontine respiratory group -modulates breathing patterns VRG- ventral respiratory group -located in the reticular formation in medulla oblongata -generates respiratory rhythm and controls accessory breathing muscles during hyperapnea DRG-dorsal respiratory group -drives inspiration and provides motor input to diaphragm and external intercostal muscles and integrates chemosensory information and commands from pontine respiratory group -modifies rhythms generated by the VRG Phrenic nerve- innervates diaphragm pontine respiratory centers--> VRG --> DRG --> phrenic nerve
How is the pitch of phonation altered (see slide 15)?
pitch is varied by the position of the arytenoid cartilage relative to the thyroid cartilage -when distance is high vocal folds tense --> increased pitch -when distance is low vocal fold relax --> decreased pitch
Be familiar with changes that occur as we age and the influence that smoking has on respiratory performance.
smoking --> continual bronchial irritation and inflammation --> chronic bronchitis (excess muscus production, chronic productive cough)--> obstruction or air trapping, dyspnea, frequent infections smoking --> breakdown of elastin in connective tissue of lungs --> emphysema (destruction of alveolar walls, loss of lung elasticity)--> air way obstruction or air trapping, dyspnea, frequent infections Effects of aging -elastic tissue deteriorate: altering lung elasticity and lowering vital capacity -arthritic changes: restricts chest movements and limit respiratory minute volume -emphysema: affects individuals over age 50 -Chronic Obstructive pulmonary disease (COPD) (atelectasis): #3 cause of death