Outline • The Respiratory Tract (includes) • The Nose • The Pharynx • The Larynx • The trachea (windpipe) • The Bronchial Tree • The Lungs • Gas Exchange • Mechanisms of Breathing • Inspiration and Expiration • Respiration and Health
The Respiratory System • During inspiration or inhalation, air is conducted toward the lungs. • During expiration or exhalation, air is conducted away from the lungs. • Works in conjunction with the cardiovascular system for RESPIRATION to occur • Breathing –air in and out of lungs • External respiration –exchange of gasses between air & blood • Internal respiration – exchange between blood &tissue fluid • Cellular respiration –production of ATP in cells
The Respiratory Tract • Two parts: • Upper Respiratory Tract • Nasal Cavities • Filter, warm and moisten air • Pharynx • Connection to surrounding regions • Glottis • Passage of air into larynx • Larynx • Sound production
The Respiratory Tract • Upper Respiratory Tract • Trachea • Passage of air to Bronchi • Bronchi • Passage of air to lungs • Bronchioles • Passage of air to each alveolus • Lungs • Gas Exchange
The Respiratory Tract As air moves towards the lungs it is cleansed, warmed, and moistened. As air moves out during expiration, it cools and deposits moisture on the lining of the trachea and the nose
The Nose • The nose contains two nasal cavities that empty into the nasopharynx. • Ciliated cells in the nasal cavities act as odor receptors • Nerves lead to the brain – interpreted as smell. • Tear glands drain into the nasal cavities. • This is why crying makes your nose run • Auditory tubes lead from the nasopharynx to the middle ears.
The Pharynx • This is a funnel-shaped passageway -connects the nasal and oral cavities to the larynx. • Three sections. • Nasopharynx - Nasal cavities open above soft palate. • Oropharynx - Oral cavity opens. • Laryngopharynx - Opens into the larynx.
The Larynx • This serves as a passageway for air between the pharynx and the trachea. • When food is swallowed, the larynx moves against the epiglottis preventing food from passing into the larynx. (Most of the time) • The larynx houses the vocal cords • Mucosal folds suspended by elastic filaments stretched across the glottis. • Air moves through glottis – vibration - sounds • The tracheais a tube connecting the larynx to the primary bronchi.
The Trachea • Windpipe – connects larynx to primary bronchi. • Held open by cartilage • Goblet cell • Makes mucus • Mucosa contains layer of pseudostratified ciliated epithelium • Sweep dirt and excess mucus upwards
The Bronchial Tree • The trachea divides into L & R primary bronchi • eventually branch into secondary bronchi and then into bronchioles. • Each bronchiole leads to an elongated space enclosed by alveoli.
The Lungs • These lie on either side of the heart within the thoracic cavity. • Total cross-sectional area of 50 – 70 meter squared (1 ½ Tennis courts) • Right lung has three lobes and the left lung has two lobes. • This allows room for the heart • Each lobe is divided into lobules, further divided into bronchioles serving many alveoli.
Alveoli • There are 300 m alveoli per set of lungs. • Each one is made up of squamous epithelium and blood capillaries. • Gas exchange occurs: O2 diffuses across the alveolar wall and enters blood – CO2 goes in other direction • Lined with lipoprotein – lowers surface tension and prevents them from closing.
Mechanism of Breathing • Respiratory Volumes • Tidal volume is the amount of air that moves in and out with each breath. • Vital capacity is the maximum amount of air that can be moved out in a single breath. • Inspiration can be increased by expanding the chest (inspiratory reserve volume). • Residual volume is the air remaining in the lungs after deep exhalation
Inspiration and Expiration • Ventilation • Normally there is a continuous column of air from the pharynx to the alveoli. • Lungs lie within sealed thoracic cavity. • Rib cage forms top and side of the cavity, while the diaphragm forms the floor. • Lungs are enclosed by two membranes, pleura.
Inspiration • Respiratory center located in the medulla oblongata - triggers inspiration. • Inspiration is the active phase of breathing. • The diaphragm and the rib muscles contract, intrapleural pressure decreases, the lungs expand, and air rushes in. • Creation of a partial vacuum in the alveoli causes air to enter the lungs.
Expiration • Respiratory center stops sending signals to the diaphragm and rib cage, the diaphragm relaxes. • Abdominal organs press up against the diaphragm, and the rib cage moves down and inward. • Expiration is usually passive as the diaphragm and external intercostal muscles are relaxed.
Gas Exchanges in the Body • External respiration refers to gas exchange between air in the alveoli and blood in the pulmonary capillaries. • Blood entering the pulmonary capillaries has a HIGHER partial pressure of CO2 than atmospheric air. • CO2 diffuses out of the blood into the lungs. • Carried in blood plasma as bicarbonate ions (HC03 ions) • Blood entering the pulmonary capillaries has a LOWER partial pressure of O2 than the avlvoli. • O2 diffuses into plasma and then red blood cells • Binds with hemoglobin – forms oxyhemoglobin
Internal Respiration • Internal respiration - gas exchange between the blood in systemic capillaries and the tissue fluid. • O2 diffuses out of the blood into the tissue because the partial pressure of O2 in tissue fluid is LOWER than that of blood. • O2 leaves hemoglobin and enters tissue fluid • CO2 diffuses into the blood from the tissue because the partial pressure of CO2 in tissue fluid is HIGHER than that of blood • CO2 combines with H20 – forms carbonic acid. Some binds to hemoglobin – forms carbaminohemoglobin
Internal Respiration occurs at systemic capillaries – that is in the major organs. • External Respiration occurs at pulmonary capillaries – that is in the lungs ONLY
Binding Capacity of Hemoglobin • Binding capacity of hemoglobin varies according to the environmental conditions in the lungs and tissues. • If the binding capacity of hemoglobin is high, hemoglobin will be saturated with oxygen. • The binding capacity of hemoglobin for oxygen is affected by • partial pressure of oxygen, temperature, and pH.
Respiration and Health • Upper Respiratory Tract Infections • Sinusitis- Infection of cranial sinuses. Excess fluid • Facial pain, tooth ache • Otitis Media - Bacterial infection of middle ear. • Hearing loss, dizziness, fever • Tonsillitis- Inflammation and enlargement of tonsils. • Lymph tissue of tonsil becomes enlarged • Laryngitis - Infection of larynx • hoarseness and inability to talk.
Respiration and Health • Lower Respiratory Tract Infections • Acute bronchitis– Affect primary & secondary bronchi. (Secondary bacterial infection) • Cough up mucus and puss • Pneumonia - Viral or bacterial infection of the lungs. • High fever, chills, headache and chest pain • Pulmonary tuberculosis - Tubercle bacillus bacterium. • Cough up blood. Cured by antibiotics
Respiration and Health • Restrictive pulmonary disorders - Vital capacity is reduced because lungs have lost elasticity. • Pulmonary fibrosis. • Fibrous connective tissue builds up in the lungs • Lungs cannot inflate correctly • Linked to asbestos • Coal miners
Respiration and Health • Obstructive pulmonary disorders - Air does not flow freely in the airways. • Chronic bronchitis • Airway inflamed and full of mucus • Pollution and smoking. • Emphysema. • Damaged walls of Alveoli. Air trapped in chest, blooming of cheat cavity • Strain on the heart • Asthma. • Allergens: reduces diameter of airways • Lung cancer.