Chap 18 The Respiratory System

Memmler’s A&P

Chap 18The Respiratory System

The Respiratory System p387•Nasal cavities•Pharynx•Larynx

•epiglottis•Trachea•Bronchi•Lungs

•Alveoli•Pleura

•Visceral pleura•Parietal pleura

Respiration p386

• Process by which oxygen is obtained from the environment and delivered to the cells. Carbon dioxide is transported to the outside in a reverse pathway.

Phases of respiration p386

• Pulmonary ventilation• External gas exchange• Internal gas exchange

Pulmonary ventilation p391inhalation/exhalation

active/passive

Gas exchange p393

•External gas exchange

•Internal gas exchange

Transport of Oxygen (O2) p394• 98.5% of O2: carried in the blood bound to

hemoglobin• Oxygenated blood is 97% saturated with O2• Deoxygenated blood is usually about 70% saturated

with O2 • To enter cells, O2 separates from hemoglobin• Carbon monoxide (CO) binds with hemoglobin at the

same molecular sites as O2. It binds more tightly and displaces O2. This is why CO is toxic.

Transport of carbon dioxide (CO2) p394

• CO2 is produced continuously in the tissues as a byproduct of cellular metabolism.

• 10% of CO2 is dissolved in plasma • 15% of CO2 is combined with the protein

portion of hemoglobin• 75% of CO2 is transported in solution in

plasma

CO2 p395• CO2 is involved in pH level of blood. • When CO2 goes into solution, hydrogen ions

(H+) are produced. • Therefore, the blood becomes more acidic as

the amount of CO2 increases to yield more H+ ions. The exhalation of CO2 shifts the blood’s pH more toward the alkaline (basic) range.

Regulation of respiration p395• Nervous control in medulla

and pons• Chemical control

– Central chemoreceptors: medulla oblongata• Monitor CO2 levels:

hypercapnia triggers respiration

• Primary chemical control: respiration is increased to blow off excess carbon dioxide gas

Regulation of respiration cont• Peripheral

chemoreceptors: located in carotid arteries and aorta

• Monitor O2 levels: hypoxic drive to breathe

• O2 levels must fall considerably below normal before this triggers breathing

•

Abnormal ventilation p396• Hyperventilation: increase in amount of air

entering alveoli– Results in increased O2 levels, decreased CO2

levels• Hypocapnia• Increase blood pH (alkalosis)• CNS excitation: dizziness, tingling, muscle twitches,

ultimately paralysis

Abnormal ventilation p396• Hypoventilation: decrease in amount of air

entering alveoli– Results in decreased O2 levels, increased CO2

levels • Hypercapnia• Decrease in blood pH (acidosis)• CNS depression: mental confusion, ultimately coma

Breathing patterns p396• Normal breathing rates: 12-20 breaths per

minute for adults• Altered breathing terms:– -pnea refers to breathing• Tachypnea• Apnea• Dyspnea• Orthopnea• Kussmaul respiration• Cheyene-Stokes respiration

Disorders of Respiratory system p396

• Infection– Sinusitis, pharyngitis, laryngitis, bronchitis

• Deviated septum• Epistaxis

Diseases of respiratory system p398• Pneumonia• Tuberculosis • Hay fever • Asthma • Chronic obstructive pulmonary disease (COPD)

COPD p399• Includes chronic bronchitis, asthma, emphysema• Obstruction to normal air flow, reduced exchange of

gases, air trapping, over inflation of alveoli. • COPD patients have a hypoxic drive to breathe.

Sudden infant death syndrome p400

• SIDS: crib death: unexplained death of seemingly healthy infant under age of 1 year.

Respiratory distress syndrome p400

• Actelectasis: incomplete expansion of lungs

Lung cancer p400

• Most common cause of cancer death in men and women

• Most important cause: cigarette smoking

Disorders involving the pleura p401

• Pleurisy: pleuritis: inflammation of pleura

• Pneumothorax: accumulation of air in pleural space

• Hemothorax: accumulation of blood in pleural space

Age and the respiratory tract p401• Tissues in respiratory tract lose elasticity and become more

rigid.• Rigidity in chest wall, combined with arthritis and loss of

strength in breathing muscles, results in overall decrease in breathing capacity.

• Increased susceptibility to infection from decreased phagocytosis.

• Gradual reduced capacity for exercise.

Respiratory treatments p402• Oxygen therapy• Suction apparatus• Artificial respiration• Bronchoscopy• Thoracentesis • Tracheostomy tube

Bronchoscopy p402

Thoracentesis 402

Tracheostomy tube p402