Inquiry into LifeTwelfth Edition

Chapter 15

Lecture PowerPoint to accompany

Sylvia S. Mader

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

15.1 The Respiratory System

• The respiratory system works with the

cardiovascular system to accomplish:– The exchange of gases (O2 and CO2) between air and

the blood

– The exchange of gases (O2 and CO2) between blood

and tissue fluid

– Transport of gases to and from the lungs and the

tissues

The Respiratory System

15.1 The Respiratory System

• The Nose– Contains two nasal cavities

• Functions– Warms air during

inhalation– Cleanses air-coarse

hairs and mucus– Humidifies air-wet

surfaces of membrane• Contain odor receptors• Tear glands drain into

nasal cavity

15.1 The Respiratory System

• The Pharynx– Connects nasal and oral

cavities to larynx– Three divisions

• Nasopharynx• Oropharynx• Laryngopharynx

– Tonsils form a protective ring

– Larynx and trachea are normally open

– Esophagus is normally closed

15.1 The Respiratory System

• The Larynx– Passageway for air between pharynx and trachea– Vocal cords

• Folds of mucosa that vibrate to make sounds– Glottis-opening between folds

• Epiglottis– Prevents food from entering the respiratory tract

15.1 The Respiratory System

• The Trachea– Connects larynx with

primary bronchi– Supported by C-

shaped cartilage rings– Cilia sweep mucus

toward the pharynx• Smoking can destroy

cilia

15.1 The Respiratory System

• The Bronchial Tree– Right and left primary bronchi

• Resemble trachea in structure– Branch to secondary bronchi

• Eventually lead to bronchioles– As airways become smaller, walls become thinner

• Lack cartilage rings– Each bronchiole leads into alveoli

15.1 The Respiratory System

• The Lungs– Divided into lobes

• Right lung has 3• Left lung has 2

– Each lobe is divided into lobules• Lobule has a bronchiole

serving many alveoli– Lungs are covered by

serous membrane called pleura

15.1 The Respiratory System

• The Alveoli– Surrounded by blood capillaries– Gas exchange occurs the moist membranes

• Oxygen diffuses into blood• Carbon dioxide diffuses into alveoli

– Alveoli must stay open to receive air• Surfactant helps prevent them from closing

15.2 Mechanisms of Breathing

• Respiratory Volumes– Tidal volume

• Amount of air moving in and out with each breath• Around 70% of this air reaches the alveoli, 30% remains in the

airways– Vital capacity

• Maximum volume moved in and moved out in a breath• Illness can affect vital capacity

– Inspiratory reserve volume• Forced inhalation (amount of air brought in above tidal volume)

– Expiratory reserve volume• Forced exhalation (air exhaled beyond tidal volume)

– Residual volume• Amount of air always remaining in lungs

Vital Capacity

15.2 Mechanisms of Breathing

• Understanding Ventilation– There is a continuous column of air from pharynx to

alveoli– The lungs lie in the sealed-off thoracic cavity

• Rib cage forms top and sides • Intercostal muscles lie between the ribs• Diaphragm forms the floor

– The lungs adhere to the thoracic wall by way of the pleura

Inspiration

Expiration

15.2 Mechanisms of Breathing

• Control of Ventilation– Controlled by respiratory center

• In medulla oblongata of brain• Inspiration

– Respiratory center sends out nerve impulses to the diaphragm and external intercostals

• Expiration– Respiratory center ceases to send out nerve impulses to

the diaphragm and external intercostals

– Input to the respiratory center• Influenced by chemical and neural input

15.2 Mechanisms of Breathing

• Chemical Input to Respiratory Center– Directly sensitive to CO2 and H+

• When levels rise, respiratory center increases rate and depth of breathing

– Indirectly responsive to O2

• Chemoreceptors in the carotid and aortic bodies– Sensitive to oxygen levels in blood– When levels decrease, impulses are sent to respiratory center

» Respiratory center then increases rate and depth of breathing

Nervous Control of Breathing

15.3 Gas Exchanges in the Body

15.3 Gas Exchanges in the Body

• External Respiration– Exchange of gas between air in alveoli and blood– Gases exert pressure

• Partial pressure refers to the amount of pressure each gas in a mixture exerts

– Symbolized by Pco2 and Po2

– Blood in pulmonary capillaries has a higher Pco2 than

atmospheric air

• CO2 diffuses from blood into alveoli

15.3 Gas Exchanges in the Body

• External Respiration Continued– Most CO2 is carried as bicarbonate ions (HCO3-)

– Carbonic anhydrase catalyzes the breakdown of carbonic acid (H2CO3)

15.3 Gas Exchanges in the Body

• External Respiration Continued– Pressure gradient for oxygen is the reverse of carbon dioxide– Po2 is low in pulmonary capillaries and high in alveoli

– Oxygen diffuses into blood– Hemoglobin picks up oxygen and becomes oxyhemoglobin

15.3 Gas Exchanges in the Body

• Internal Respiration– Exchange of gas between systemic capillaries and tissues– Partial pressure of oxygen is greater in capillaries than tissues– Oxyhemoglobin gives up oxygen which diffuses out of the blood

into tissues

15.3 Gas Exchanges in the Body

• Internal Respiration– CO2 diffuses into the blood

• A small amount combines with hemoglobin – Most CO2 combines with H2O– Carbonic anhydrase speeds up the reaction

15.4 Disorders of the Respiratory System

• Disorder of the Upper Respiratory Tract

– The Common Cold• Caused by viruses• Sneezing, runny nose, mild fever (in some

instances)• Last a few days to a week• Antibiotics are ineffective against viral infections

15.4 Disorders of the Respiratory System

• Disorder of the Upper Respiratory Tract– Pharyngitis

• Inflammation of the throat• May be caused by Streptococcus pyogenes (Strep throat)

– Severe sore throat, high fever, white patches in throat region

– Tonsillitis• Tonsils (lymphoid tissue) become inflamed and enlarged

– Laryngitis• Inflammation of the larynx

– Causes hoarseness– Persistent laryngitis is one warning sign of cancer

15.4 Disorders of the Respiratory System

• Disorder of the Upper Respiratory Tract– Sinusitis

• Infection of the cranial sinuses• Nasal congestion blocks sinus openings• Symptoms include postnasal discharge, headache, and facial pain

– Otis Media• Inflammation of the middle ear• Nasal infections spread to the ear by way of the auditory tubes• Antibiotics are usually an effective treatment

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract– Choking

• Obstruction of the trachea

• Heimlich maneuver may expel blockage

• A tracheostomy is the insertion of a breathing tube into the

trachea

• Symptoms include postnasal discharge, headache, and

facial pain

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract– Acute bronchitis

• Infection of the primary and secondary bronchi

• Usually it is preceded by a viral infection that leads to a

secondary bacterial infection

– Chronic bronchitis• Airways are inflamed and filled with mucus

• Bronchi have undergone degenerative change including the

loss of cilia

• Smoking is the most common cause

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract– Asthma

• A disease of the bronchi and bronchioles– Wheezing, breathlessness, coughing

– Inflammation of the bronchioles

• Airways are usually sensitive to specific irritants

• Incurable but can be treated with medicines

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract– Pneumonia

• Viral or bacterial infection

• Bronchi or alveoli fill with fluid

• High fever, chest pain and headache

– Pulmonary tuberculosis• Caused by the bacterium Mycobacterium tuberculosis

• Cells build a protective capsule (tubercle) around the

bacteria

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract– Emphysema

• Damage to the walls of the alveoli

• A chronic and incurable disease

• Smoking is the major cause of this disease

– Cystic fibrosis (CF)• Genetic in origin

• A recessive condition

• Mucus in the lungs becomes very thick and sticky

15.4 Disorders of the Respiratory System

• Disorder of the Lower Respiratory Tract

– Pulmonary fibrosis

• Fibrous connective tissue builds up in the lungs causing a

lack of elasticity

• This reduces vital capacity

Common Bronchiole and Pulmonary Diseases

15.4 Disorders of the Respiratory System

• Lung Cancer– A series of progressive steps

• Thickening and callusing of mucosa of bronchi• Loss of cilia• Cancerous changes occur in callus cells• Tumors may obstruct bronchi• Cancerous cells spread to other parts of the body

– Lung cancer can be caused by secondhand smoke

Normal Lung versus Cancerous Lung