THE RESPIRATORY SYSTEM

THE HUMAN RESPIRATORY SYSTEM Organs of the Respiratory System 1.Nose 2.Pharynx 3.Larynx 4.Trachea 5.Bronchi 6.Alveoli 7.Lungs (Pleura)

Function of the Respiratory System Oversees gas exchanges between the blood and external environment Oversees gas exchanges between the blood and external environment Exchange of gasses takes place within the lungs in the alveoli Exchange of gasses takes place within the lungs in the alveoli Passageways to the lungs purify, warm, and humidify the incoming air Passageways to the lungs purify, warm, and humidify the incoming air

Organs of the Respiratory System

Upper Respiratory System 1. The Nose  The only externally visible part of the respiratory system  Air enters the nose through the external nares (nostrils)  The interior of the nose consists of a nasal cavity divided by a nasal septum  Warms, moistens, and filters air 2. Pharynx  Muscular passage from nasal cavity to larynx

3. Larynx  Plays a role in speech (vocal cords)  Vibrate with expelled air to create sound (speech)  Glottis – opening between vocal cords 4. Epiglottis  Spoon-shaped flap of elastic cartilage  Superior opening of the larynx  Routes food to the esophagus and air toward the trachea

Action of the epiglottis

5. Trachea Connects larynx with bronchi Connects larynx with bronchi Made of eight rigid hyaline cartilages Made of eight rigid hyaline cartilages Thyroid cartilage is the largest hyaline cartilage Thyroid cartilage is the largest hyaline cartilage Protrudes anteriorly (Adam’s apple) Protrudes anteriorly (Adam’s apple) Lined with ciliated mucosa Lined with ciliated mucosa Beat continuously in the opposite direction of incoming air Beat continuously in the opposite direction of incoming air Expel mucus loaded with dust and other debris away from lungs Expel mucus loaded with dust and other debris away from lungs Walls are reinforced with C-shaped hyaline cartilage Walls are reinforced with C-shaped hyaline cartilage

Upper Respiratory System

The Lower Respiratory System 6. Bronchi  Formed by division of the trachea  Enters the lung at the hilus (medial depression)  Right bronchus is wider, shorter, and straighter than left  Bronchi subdivide into smaller and smaller branches 7. Bronchioles  Smallest branches of the bronchi  All but the smallest branches have reinforcing cartilage  Terminal bronchioles end in alveoli

The Lower Respiratory System 8.Alveoli Gas exchange takes place within the alveoli in the respiratory membrane Gas exchange takes place within the alveoli in the respiratory membrane Thin cellular layer lining alveolar walls Thin cellular layer lining alveolar walls Pulmonary capillaries cover external surfaces of alveoli Pulmonary capillaries cover external surfaces of alveoli 9. Lungs Occupy most of the thoracic cavity Occupy most of the thoracic cavity Apex is near the clavicle (superior portion) Apex is near the clavicle (superior portion) Base rests on the diaphragm (inferior portion) Base rests on the diaphragm (inferior portion) Each lung is divided into lobes by fissures Each lung is divided into lobes by fissures Left lung – two lobes Left lung – two lobes Right lung – three lobes Right lung – three lobes

The Lower Respiratory System 10. Pleura  Pulmonary (visceral) pleura covers the lung surface

Gas Exchange Gas crosses the respiratory membrane by diffusion Oxygen enters the blood Oxygen enters the blood Carbon dioxide enters the alveoli Carbon dioxide enters the alveoli

Complete the Lab Anatomy of the Respiratory System

Events of Respiration

Pulmonary ventilation: air in and out of the lungs Pulmonary ventilation: air in and out of the lungs External respiration: gas exchange between the alveoli and the blood External respiration: gas exchange between the alveoli and the blood Transport: oxygen and carbon dioxide being transported to and from the body cells Transport: oxygen and carbon dioxide being transported to and from the body cells Internal respiration: gas exchange between the blood and the body cells Internal respiration: gas exchange between the blood and the body cells

Events of Respiration In more detail

Pulmonary ventilation Moving air in and out of the lungs (breathing in and out) We will further explore this in the section “Mechanics of Breathing”

External Respiration Exchange of gases between the alveoli of the lungs and the capillaries of the blood stream Exchange of gases between the alveoli of the lungs and the capillaries of the blood stream

External Respiration Oxygen movement into the blood Oxygen movement into the blood The alveoli always has more oxygen than the blood The alveoli always has more oxygen than the blood Oxygen moves by diffusion towards the area of lower concentration Oxygen moves by diffusion towards the area of lower concentration Pulmonary capillary blood gains oxygen Pulmonary capillary blood gains oxygen Carbon dioxide movement out of the blood Carbon dioxide movement out of the blood Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli Pulmonary capillary blood gives up carbon dioxide Pulmonary capillary blood gives up carbon dioxide Blood leaving the lungs is oxygen-rich and carbon dioxide-poor Blood leaving the lungs is oxygen-rich and carbon dioxide-poor

External Respiration

Gas Transport in the Blood Oxygen transport in the blood Oxygen transport in the blood Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO 2 ]) Inside red blood cells attached to hemoglobin (oxyhemoglobin [HbO 2 ]) A small amount is carried dissolved in the plasma A small amount is carried dissolved in the plasma Carbon dioxide transport in the blood Carbon dioxide transport in the blood Most is transported in the plasma as bicarbonate ion (HCO 3 –) Most is transported in the plasma as bicarbonate ion (HCO 3 –) A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen A small amount is carried inside red blood cells on hemoglobin, but at different binding sites than those of oxygen

Gas Transport in the Blood

Internal Respiration Exchange of gases between the blood and body cells Exchange of gases between the blood and body cells An opposite reaction to what occurs in the lungs (external respiration) An opposite reaction to what occurs in the lungs (external respiration) Carbon dioxide diffuses out of tissue to blood Carbon dioxide diffuses out of tissue to blood Oxygen diffuses from blood into tissue Oxygen diffuses from blood into tissue

Internal Respiration

The Mechanics of Breathing (Pulmonary ventilation) see Figure 13.7 on pg 3 in your packet Completely mechanical process Completely mechanical process Depends on volume changes in the thoracic cavity Depends on volume changes in the thoracic cavity Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure Two phases Two phases Inspiration – flow of air into lung Inspiration – flow of air into lung Expiration – air leaving lung Expiration – air leaving lung

Inspiration Diaphragm and intercostal muscles contract Diaphragm and intercostal muscles contract The size of the thoracic cavity increases The size of the thoracic cavity increases External air is pulled into the lungs due to an increase in intrapulmonary volume External air is pulled into the lungs due to an increase in intrapulmonary volume

Expiration Largely a passive process which depends on natural lung elasticity Largely a passive process which depends on natural lung elasticity As muscles relax, air is pushed out of the lungs As muscles relax, air is pushed out of the lungs Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage

Pressure Differences in the Thoracic Cavity Normal pressure within the pleural space is always negative (intrapleural pressure) Normal pressure within the pleural space is always negative (intrapleural pressure) Differences in lung and pleural space pressures keep lungs from collapsing Differences in lung and pleural space pressures keep lungs from collapsing

External Respiration, Gas Transport, and Internal Respiration Summary (page 5 in your packet)

Non-respiratory Air Movements (not in your notes) Can be caused by reflexes or voluntary actions Can be caused by reflexes or voluntary actions Examples Examples Cough and sneeze – clears lungs of debris Cough and sneeze – clears lungs of debris Laughing Laughing Crying Crying Yawn Yawn Hiccup Hiccup

Respiratory Sounds (not in your notes) Sounds are monitored with a stethoscope Sounds are monitored with a stethoscope Bronchial sounds – produced by air rushing through trachea and bronchi Bronchial sounds – produced by air rushing through trachea and bronchi Vesicular breathing sounds – soft sounds of air filling alveoli Vesicular breathing sounds – soft sounds of air filling alveoli

Neural Regulation of Respiration (page 4 in your packet) Activity of respiratory muscles is transmitted to the brain by the phrenic and intercostal nerves Activity of respiratory muscles is transmitted to the brain by the phrenic and intercostal nerves Neural centers that control rate and depth are located in the medulla Neural centers that control rate and depth are located in the medulla The pons appears to smooth out respiratory rate The pons appears to smooth out respiratory rate Normal respiratory rate (eupnea) is 12–15 respirations per minute Normal respiratory rate (eupnea) is 12–15 respirations per minute Hypernia is increased respiratory rate often due to extra oxygen needs Hypernia is increased respiratory rate often due to extra oxygen needs

Factors Influencing Respiratory Rate and Depth Physical factors Physical factors Increased body temperature Increased body temperature Exercise Exercise Talking Talking Coughing Coughing Volition (conscious control) Volition (conscious control) Emotional factors Emotional factors

Factors Influencing Respiratory Rate and Depth Chemical factors: Carbon dioxide levels Level of carbon dioxide in the blood is the main regulatory chemical for respiration Level of carbon dioxide in the blood is the main regulatory chemical for respiration Increased carbon dioxide increases respiration Increased carbon dioxide increases respiration Changes in carbon dioxide act directly on the medulla oblongata Changes in carbon dioxide act directly on the medulla oblongata Oxygen levels Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and carotid artery Changes in oxygen concentration in the blood are detected by chemoreceptors in the aorta and carotid artery Information is sent to the medulla oblongata Information is sent to the medulla oblongata

Respiratory Rate Changes throughout Life Respiratory Rate Changes throughout Life  Newborns – 40 to 80 respirations per minute  Infants – 30 respirations per minute  Age 5 – 25 respirations per minute  Adults – 12 to 18 respirations per minute  Rate often increases somewhat with old age

Aging Effects  Elasticity of lungs decreases  Vital capacity decreases  Blood oxygen levels decrease  Stimulating effects of carbon dioxide decreases  More risks of respiratory tract infection

Developmental Aspects of the Respiratory System (not in your notes) Lungs are filled with fluid in the fetus Lungs are filled with fluid in the fetus Lungs are not fully inflated with air until two weeks after birth Lungs are not fully inflated with air until two weeks after birth Surfactant that lowers alveolar surface tension is not present until late in fetal development and may not be present in premature babies Surfactant that lowers alveolar surface tension is not present until late in fetal development and may not be present in premature babies Important birth defects Important birth defects Cystic fibrosis – over secretion of thick mucus clogs the respiratory system Cystic fibrosis – over secretion of thick mucus clogs the respiratory system Cleft palate Cleft palate

Complete the Lab Respiratory System Physiology

Respiratory Vocabulary Eupnea = normal breathing rate Hypernea = abnormal breathing Dyspnea = difficult or labored breathing Apnea = cessation of (stopped) breathing

Respiratory Volumes and Capacities (Page 3 in your packet)

Tidal volume [TV] Normal breathing moves about 500 ml of air with each breath Normal breathing moves about 500 ml of air with each breath Many factors that affect respiratory capacity Many factors that affect respiratory capacity A person’s size A person’s size Sex Sex Age Age Physical condition Physical condition

Inspiratory reserve volume (IRV) Amount of air that can be taken in forcibly over the tidal volume Amount of air that can be taken in forcibly over the tidal volume Usually between 2100ml and 3200 ml Usually between 2100ml and 3200 ml

Expiratory reserve volume (ERV) Amount of air that can be forcibly exhaled Amount of air that can be forcibly exhaled Approximately 1200 ml Approximately 1200 ml

Residual volume Air remaining in lung after expiration Air remaining in lung after expiration About 1200 ml About 1200 ml

Vital capacity The total amount of exchangeable air The total amount of exchangeable air Vital capacity = TV + IRV + ERV Vital capacity = TV + IRV + ERV Dead space volume Dead space volume Air that remains in conducting zone and never reaches alveoli Air that remains in conducting zone and never reaches alveoli About 150 ml About 150 ml

Respiratory Volumes and Capacities

Complete the Lab Spirometry in Respiratory Function

Respiratory Disorders

Chronic Obstructive Pulmonary Disease (COPD) Exemplified by chronic bronchitis and emphysema Exemplified by chronic bronchitis and emphysema Major causes of death and disability in the United States Major causes of death and disability in the United States Features of these diseases Features of these diseases Patients almost always have a history of smoking Patients almost always have a history of smoking Labored breathing (dyspnea) becomes progressively more severe Labored breathing (dyspnea) becomes progressively more severe Coughing and frequent pulmonary infections are common Coughing and frequent pulmonary infections are common Most victims retain carbon dioxide, are hypoxic and have respiratory acidosis Most victims retain carbon dioxide, are hypoxic and have respiratory acidosis Those infected will ultimately develop respiratory failure Those infected will ultimately develop respiratory failure

Emphysema Alveoli enlarge as adjacent chambers break through Alveoli enlarge as adjacent chambers break through Chronic inflammation promotes lung fibrosis Chronic inflammation promotes lung fibrosis Airways collapse during expiration Airways collapse during expiration Patients use a large amount of energy to exhale Patients use a large amount of energy to exhale Over inflation of the lungs leads to a permanently expanded barrel chest Over inflation of the lungs leads to a permanently expanded barrel chest Cyanosis appears late in the disease Cyanosis appears late in the disease

An emphysema lung An emphysema lung

Chronic Bronchitis Mucosa of the lower respiratory passages becomes severely inflamed Mucosa of the lower respiratory passages becomes severely inflamed Mucus production increases Mucus production increases Pooled mucus impairs ventilation and gas exchange Pooled mucus impairs ventilation and gas exchange Risk of lung infection increases Risk of lung infection increases Pneumonia is common Pneumonia is common Hypoxia and cyanosis occur early Hypoxia and cyanosis occur early

Chronic Bronchitis

Lung Cancer Accounts for 1/3 of all cancer deaths in the United States Accounts for 1/3 of all cancer deaths in the United States Increased incidence associated with smoking Increased incidence associated with smoking Three common types Three common types Squamous cell carcinoma Squamous cell carcinoma Adenocarcinoma Adenocarcinoma Small cell carcinoma Small cell carcinoma

Lung Cancer

Sudden Infant Death syndrome (SIDS) Apparently healthy infant stops breathing and dies during sleep Apparently healthy infant stops breathing and dies during sleep Some cases are thought to be a problem of the neural respiratory control center Some cases are thought to be a problem of the neural respiratory control center One third of cases appear to be due to heart rhythm abnormalities One third of cases appear to be due to heart rhythm abnormalities

Asthma Chronic inflamed hypersensitive bronchiole passages Chronic inflamed hypersensitive bronchiole passages Response to irritants with dyspnea, coughing, and wheezing Response to irritants with dyspnea, coughing, and wheezing Treated with medications and inhalers Treated with medications and inhalers

Asthma

Cystic Fibrosis Most common lethal genetic disease Most common lethal genetic disease Thick mucus production causes problems with breathing and digestion Thick mucus production causes problems with breathing and digestion Salty sweat (diagnosed with a sweat test) Salty sweat (diagnosed with a sweat test)

Cystic Fibrosis In people with cystic fibrosis, mucus in the airways is thicker than normal. The body also produces more mucus, and mucus tends to build up. The result is obstruction of airways—which makes breathing difficult—and the creation of an environment for infection-causing bacteria to grow.

Pneumonia Infection in the lungs Infection in the lungs Caused by Caused by Bacteria (treatable with antibiotics) Bacteria (treatable with antibiotics) Virus Virus fungus fungus

Pneumonia

Whooping Cough Also called percussis Also called percussis Cough with a whooping sound Cough with a whooping sound Cough so hard that a person vomits, can’t catch his breath, or even turns blue Cough so hard that a person vomits, can’t catch his breath, or even turns blue Children are now immunized for this disease Children are now immunized for this disease

Tuberculosis Commonly called TB Commonly called TB Caused by a bacteria that usually attacks the lungs – the bacteria will destroy tissue Caused by a bacteria that usually attacks the lungs – the bacteria will destroy tissue Spread from one person to another by air Spread from one person to another by air Skin test for the presence of the bacteria Skin test for the presence of the bacteria

Tuberculosis Latent TB – persons who have the bacteria but do not get sick (they do not spread it, but they may become sick later) Latent TB – persons who have the bacteria but do not get sick (they do not spread it, but they may become sick later) Active TB - symptoms include Active TB - symptoms include Bad cough lasting 3 weeks or longer Bad cough lasting 3 weeks or longer Pain in chest Pain in chest Coughing up blood Coughing up blood Weakness or fatigue Weakness or fatigue Loss of appetite – weight loss Loss of appetite – weight loss Chills and fever Chills and fever Night sweats Night sweats