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The Respiratory System. The Respiratory tract. Conducting passageways carrying air to and from the alveoli Upper respiratory passages filter and humidify incoming air Lower passageways include delicate conduction passages and alveolar exchange surfaces.
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The Respiratory tract • Conducting passageways carrying air to and from the alveoli • Upper respiratory passages filter and humidify incoming air • Lower passageways include delicate conduction passages and alveolar exchange surfaces
Respiratory Mucosa • This mucus protects delicate lower respiratory track by filtering out dust, dirt, and pathogens • This mucus is then removed from the body or sent to the stomach for the stomach acid to destroy pathogens
The Respiratory System has two Major Responsibilities • Supply the blood (and ultimately the tissues) with O2. • Remove CO2 • Simply stated: Respiration involving breathing O2 in and expelling CO2. • However, it’s more complicated than that.
The Two types of respiration • Internal Respiration: within the cells, cellular respiration • External Respiration: involves movement of air and gasses
Internal Respiration • Internal respiration refers to the metabolic processes occurring using sugar and oxygen making energy in the mitochondria. • Molecular oxygen is used by tissue cells. • Carbon dioxide is produced
2 Types of Internal Respiration • Aerobic respiration – With Oxygen • C6H12O6 + 6O2 6CO2 + 6 H2O + 36 or 38 ATP • Anaerobic respiration – Without Oxygen • C6H12O6 2CO2 + 2C2H5OH + 2 ATP
External Respiration • The sequence of events involved in the exchange of O2 and CO2 between the external environment and body’s cells. • It includes: • Breathing: air moved between the atmosphere and Lungs (alveoli). • Gasses exchanged between the lungs and the blood. • Movement of gasses between the lungs and the tissues.
Each Step Has Two Parts or Halves. • The first half involves getting O2 into the body. • The second half involves getting CO2 out of the body.
1st: Getting O2 into the body • O2 from the atmosphere into lungs (alveoli). (Pulmonary Ventilation) • O2 from the alveoli into pulmonary capillaries. (Pulmonary Diffusion) • O2 from lungs (pulmonary capillaries) to the tissues (blood/gas transport) • O2 from blood into the tissues. (Blood/ gas tissue exchange)
2nd: CO2 out of the body (reverse order) • 4. CO2 from the tissues to the blood. (blood/gas tissue exchange) • CO2 from the tissues to the lungs (blood/gas transport) • 2. CO2 from the pulmonary capillaries to the alveoli. (Pulmonary Diffusion) • CO2 from the lungs (alveoli) to the atmosphere. (Pulmonary Ventilation)
The Respiratory System Consists of Three Parts • The Air Passages • The Lungs • The Breathing (Thoracic Muscles) • Intercostals muscles – muscles between your ribs, when they contract the rib cage opens and are only active during inspiration • Diaphragm – muscle that is attached to the bottom of your lungs, When it contracts it lowers and is only active during inspiration
Airways conduct air between the atmosphere and alveoli. • Inhaled air passes through the following series of continuous airways in this sequence: • Nasal passages • Pharynx • Larynx • Trachea • Bronchi (left and right) • Bronchioles • Alveoli
Each Part has a Specific Purpose • The Nasal Passages & Mouth lead to the Pharynx (throat). • The Pharynx branches into two tubes. • One becomes the esophagus (for food to the stomach) • The other goes through the larynx to the trachea • The larynx (voice box) has vocal folds. • It has two strong elastic, connective bands which vibrate when air passes over them. • Along with the tongue, teeth and palate, speech is possible • The bands tighten up when swallowing to prevent passage of food into the trachea • The Trachea divides into two tubes
Air Passages continue from the Trachea • At the base of the trachea, this respiratory tract spits into a right and left bronchus. • The walls of the trachea and bronchi are reinforced with rings of cartilage. (holds windpipe open) • The bronchi continue to split into smaller tubes, bronchioles. The cartilage is absent in the bronchioles. • The bronchioles are smooth muscle tubes, capable of changing the airflow through them by dilating and constricting. • At the end of each bronchiole is a cluster of air sacs called: Alveoli
Alveoli • The Alveoli are the actual exchange sites of the gases. • Up to this point, the air passages simply provide a method to get air (O2 & CO2) into and out of the lungs. • No exchange of gasses has occurred.
The alveoli are thin-walled, single-celled inflatable sacs. • Gas exchange is their function. They are encircled by pulmonary capillaries. • We have about 300 million alveoli. • The alveoli offer tremendous surface area for gas exchange by diffusion. • Equal to the size of a tennis court (75-80 Sq. meters).
Changes in the intra-alveolar pressure produces the flow of air into and out of the lungs. • If intra-alveolar pressure is less than atmospheric pressure (inhaling), air enters the lungs. • If the opposite occurs (exhalling), air exits from the lungs. • So air moves by pressure differential (gradient).
Most Oxygen in the blood is transported via hemoglobin. • Hemoglobin combines with oxygen in the lungs to form oxyhemoglobin. (97.5%) • A small percentage of oxygen is dissolved in the plasma. (2.5%) • At the tissue cells oxyhemoglobin dissociates into hemoglobin and free molecules of oxygen. • The reaction is favored in this direction as oxygen leaves the systemic capillaries and enters tissue cells.
After Oxygen has been delivered to the tissues, CO2 must be returned to the lungs • CO2 is transported in three ways: • Dissolved in the blood (10%) • Bound to hemoglobin (30%) • As buffered Bi-carbonate ion (60%) • Also called carbonic acid
Respiration is a controlled process. • There are respiratory centers in the brain stem that establish a rhythmic breathing pattern. • There are inspiratory and expiratory neurons in the medullary respiratory center. • The inspiratory neurons send signals to the inspiratory muscles. • When they do not fire signals, the expiratory center takes over and expiration occurs.
