Anatomy and Physiology 6.pdf

Wk 4: Feb 2, 2023 Unit 6: The Respiratory System Overall Functions of the Respiratory System Gas Exchange: exchanged of O2 and CO2 between the atmosphere and blood occurs in the lungs. Communication: as air passes through the respiratorias passageways — complex speech, vocalización (laughing and cry...

Wk 4: Feb 2, 2023 Unit 6: The Respiratory System Overall Functions of the Respiratory System Gas Exchange: exchanged of O2 and CO2 between the atmosphere and blood occurs in the lungs. Communication: as air passes through the respiratorias passageways — complex speech, vocalización (laughing and crying) and even the babbling of babies. Sense of Smell: chemoreceptors in the nose allow us to perceive doors. Acid-Base Balance: CO2 reacts with H2O to produce acid —> Blood pH rises to high: can be lower by slowing our breathing to allow more CO2 to accumulate. —> Blood pH falls to low: can be raised by exhaling CO2 faster than the body produces it. Expulsion of Abdominal Contents: a breath-holding Valsalva maneuver (the action of attempting to exhale with the nostrils and mouth, or the glottis, closed.) helps to expel abdominal contents during urination, defecation, and childbirth. Importance of the Respiratory System as a Homeostatic Mechanism Concentration of O2 and CO2 are sufficient and can keep up with the demands in the body. Organs of the Respiratory System The Nose (Nasal cavity) The Pharynx The Larynx The Trachea The Lungs, Pleurae, and Bronchial Tree The Alveoli The upper respiratory tract: consists of the nose, mouth, sinuses, pharynx, and larynx. The lower respiratory tract: consists of the trachea, bronchial tubes, and lungs. Respiratory Mucosa Most of the nasal cavity is lined with respiratory epithelium of the ciliated, pseudostratified columnar type. Inhaled dust, pollen, bacteria, and other foreign matter cling to the sticky mucus. Which si swept by cilia into the pharynx (this mucus is swallowed and most of the debris is kept away from the lungs). The Nose: during normal breathing Nares (Nostrils): air is drawn through nostrils. — Have stiff guard hairs (vibrissae), that prevent insects and large airborne particles from entering. — Extends posteriorly to the posterior nasal apertures (choanae), that lead into the throat. Nasal Cavity: divided into right and left halves by a wall, the nasal septum (composed of bone and hyaline cartilage). — The roof and walls of the cavity are formed by the ethmoid and sphenoid bones. — Floor is formed by the palate, which separated the nasal cavity from the oral cavity and allows you to breath while eating food. —> Hard Palate: is bony, anteriorly. —> Soft Palate: is fleshy, posteriorly. Nasal Conchae (inward folds): lateral walls of the nasal cavity — They cause the airflow to be turbulent. —> Inhaled air contacts the mucous membrane covering the conchae, it is warmer, humidified, and cleansed of most of its debris. Paranasal Sinuses: small hollow spaces in the bones around the nose (frontal sinus, maxillary sinus, ethmoid sinus, and sphenoid sinus). —> Their functions are lightening the weight if the head, humidifying and heating inhaled air, increasing the resonance of speech. Lacrimal Sacs: fluid produced by the eyes (tears) drain into the nasal cavities. Fluid flows into the pharynx same as the mucus flow and ultimately ended in our digestive system. The Pharynx: is a muscular funnel that facilitates spa allowing and speech. It extends from the posterior nasal apertures to the larynx and esophagus and consists of 3 categories 1. Nasopharynx: space superior to the soft palate. Servers as a passageway for air. Here you can find the pharyngeal tonsil. — The pharyngotympanic (Auditory) tube from the middle are opens into the nasopharynx. — Lined with pseudostratified columnar epithelium. 2. Oropharynx: lies between the soft palate and root of the tongue. — It contains the palatine and lingual tonsils and serves as a passageway for both food and air. — Lined with stratified squamous epithelium. 3. Laryngopharynx: lies mostly behind the larynx, ending where the esophagus begins. — Lined with stratified squamous epithelium (to accommodate passage of food) The Larynx (or voice box): chamber composed mainly of cartilage and muscle. It’s main function is to prevent food and drink form entering the airway. Sound productions is an additional role. Framed by 9 cartilages: largest is the Thyroid cartilage. A large Cricoid cartilage and its ligaments attach the inferior end of the larynx to the trachea. Other smaller cartilages provide support to soft tissues, operate the vocal cords, and shape the epiglottis. The Epiglottis: a spoon-shaped flap that seals the lay gear opening during swallowing, the root of the tongue pushes the epiglottis downward while muscles attached to the Thyroid cartilage pull the larynx up to meet it. Epiglottis caps the opening like a lid which allows the food and drink to be diverted to the esophagus, behind the larynx. If any water or food gets into the larynx (past the epiglottis) it triggers a cough reflex to help expel the liquid/food and avoid it getting into the lungs. Vocal Cords: stretch like a V from the midpoint of the Thyroid cartilage in front to 2 small, mobile cartilages posteriorly. Glottis: the vocal cords and the opening between them. Airflow through the glottis vibrates the vocal cords and produces sound. The Trachea or “windpipe”: is about 12 cm long and 2.5 cm in diameter. At its inferior end, it forks into the left and right bronchi. Lined with a ciliated pseudostratified columnar epithelium rich in mucus-producing goblet cells. Cilia sweeps the mucus and foreign particles upward toward the the throat, away front the lungs. The Trachea is supported by 16 to 20 C-shaped rings of Hyaline Cartilage, some can be felt at the front of the neck. — The rings reinforced the trachea and keep it from collapsing when we inhale. The Bronchial Tree: is a series of branching passages that carry air from the trachea to the gas-exchange surfaces in the lungs. Primary Bronchi: leads to the lungs. Right main bronchus is slightly wider and more vertical than the left one. Lined with ciliated pseudostratified columnar epithelium. — Supported by rings of hyaline cartilage and have a layer of smooth muscle. Secondary Bronchi: — Main Bronchi (right): branches into superior, middle and inferior lobar that supply each lobe of the lungs. — Left Bronchi: branches into superior and inferior lobar only. The Bronchioles: tubes less than 1 mm in diameter and with NO cartilage. Supported by smooth muscle, they have the capacity to dilate (bronchodilation) and constrict (broncoconstriction) than the larger bronchi. Lined with ciliated cuboidal epithelium. Bronchioles branch into smaller divisions called Terminal Brochioles. Conducting Zone: from nasal cavity through terminal brochioles — it functions only for airflow. Respiratory Zone: Respiratory bronchioles —> alveolar ducts —> alveolar sacs Path of airflow: Nasal Cavity Pharynx Trachea Conducting Zone Main Bronchus Lobar Bronchus Segmental Bronchus (tertiary, not on objectives) Bronchiole Terminal Bronchiole Respiratory Bronchiole Respiratory Zone Alveolar Duct Alveolus The Alveoli: Alveolus: is a pouch about 0.2 to 0.5 mm in diameter. Each lung contains approx. 150 million alveoli which provides large surface area for gasexchange Alveoli are lined mostly with squamous alveolar cells. Great Alveolar Cells: are found in the walls of each alveolus. They secrete pulmonary surfactant (a substance that prevents the walls of the alveoli from sticking together and collapsing — a detergent-like lipoprotein which decreases cohesiveness in water molecules). Alveolar Macrophages: cell, that wander the alveoli and phagocyte dust particles or pathogens that escape the mucociliary escalator (cilia that removes particles moving them upward out of the lungs). Each alveolus is covered with a web of blood capillaries. Gas-exchange occurs here where the respiratory membrane is very thin (consists of squamous alveolar cell, the squamous endothelial cell that lines the capillary, and their shared thin basement membrane). Alveolar Ducts: are the tiny end ducts of the branching airways that fill the lungs. Alveolar Sacs: this air sacs at the end of the bronchioles. Extends from the Alveolar Ducts. Alveolar Pores: are discrete holes in walls of adjacent alveoli. Openings that connect alveoli. The Lungs: soft, spongy organs that occupy most of the thoracic cavity. (Right and left pleura cavities). Separated by the Mediastinum. Lungs are cone-shaped with a broad base (inferiorly); the apex (superiorly); a broad, curved costal surface (lines the rib cage); and a mediastinal surface (facing the heart). Right Lung: is divided into 3 lobes. Left lung: is divided into 2 lobes. Pleura: a serous membrane that lines the thoracic wall and adheres to the lungs. —> Parietal Pleura: lines the inner surface of the rib cage. —> Visceral Pleura: forms the outer surface of the lung. Pulmonary Arteries: blood vessels that carry O2-poor blood from the right side of the heart to the lungs. Bronchial Arteries: delivers blood to the lungs to nourish their tissues. Pulmonary Ventilation Consists of inspiration (inhaling — air in) and expiration (exhaling — air out). One complete inspiration and expiration is called a respiratory cycle. External Respiration Refers to the loading of O2 ( oxygen moves from alveoli to pulmonary veins) and unloading of CO2 ( carbon dioxide moves from pulmonary arteries to blood in the capillaries of the alveoli). Internal Respiration Refers to the unloading of O2 (oxygen moves from arteries into tissues — systemic capillaries) and the loading of CO2 ( carbon dioxide moves from tissues to blood into veins — systemic capillaries). Cellular (Aerobic) Respiration Occurs in the presence of oxygen and oxidizes pyruvate (end product of glycolysis) to carbon dioxide and water. Creation of ATP (adenosine triphosphate) a form of energy used by the body. Takes place in the mitochondria.