Transcript Ch 23 Respiratory Notes

Chapter 23
The Respiratory System
Lecture Outline
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INTRODUCTION
• Respiration is the exchange of gases between the
atmosphere, blood, and cells.
• Respiration also helps adjust the pH of body fluids.
• It takes place in three basic steps: ventilation (breathing),
external (pulmonary) respiration, and internal (tissue)
respiration.
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Respiratory System Anatomy
• Upper respiratory system:
– Nose
– Pharynx = throat
• Lower Respiratory system:
– Larynx = voice box
– Trachea = windpipe
– Bronchi = airways
– Lungs
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External Anatomy
• The external portion of the nose is made of cartilage and
skin and is lined with mucous membrane.
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Internal Anatomy
• The interior structures of the nose are specialized for:
– warming, moistening, and filtering incoming air
– receiving olfactory stimuli
– serving as large, hollow resonating chambers to modify
speech sounds.
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Nose -Internal
Structures
•
•
•
•
Large chamber within the skull
Roof is made up of bone and floor is hard palate
Internal nares are openings to pharynx
Nasal septum is composed of bone & cartilage
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Rhinoplasty
• Rhinoplasty (“nose job”) is a surgical procedure in which
the structure of the external nose is altered for cosmetic or
functional reasons (fracture or septal repair)
• Procedure
– local and general anesthetic
– nasal cartilage is reshaped through nostrils
– bones fractured and repositioned
– internal packing & splint while healing
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Pharynx
• Muscular tube (5 inch long) hanging
from skull
• Extends from the nose to voice box
(larynx)
• Functions
– passageway for food and air
– resonating chamber for speech
production
– Tonsils, found in the wall,
participate in immunological
reactions against foreign invaders
• Distinct regions -- nasopharynx,
oropharynx and laryngopharynx
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Nasopharynx
• Passageway for air only
– Location of the tonsils
– Equalizes pressure with the ears
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Oropharynx
• Common passageway for food & air
– Is open to the mouth
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Laryngopharynx
• Common passageway for food & air
– Begins at the hyoid bone
– Ends at the esophagus and the larynx
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Larynx - Overview
• The larynx (voice box) is a passageway that connects the
pharynx with the trachea.
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Cartilages
of the
Larynx
• Thyroid cartilage forms Adam’s apple
• Epiglottis---leaf-shaped piece of elastic cartilage that
keeps food out of our lungs
• Glottis-location of vocal cords
• Cartilages-form the structure of the larynx
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The Structures of Voice Production
• True vocal cord contains both skeletal muscle and an
elastic ligament.
• Made of 10 small muscles and ligaments.
• The tighter the ligament, the higher the pitch
• To increase volume of sound, push air harder
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Speech and Whispering
• Speech is modified sound made by the larynx.
• Speech requires pharynx, mouth, nasal cavity & sinuses to
resonate that sound
• Tongue & lips form words
• Whispering is forcing air through almost closed glottis,
vocal cords do not vibrate
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Trachea
• The windpipe
• Size is 5 in long & 1 in diameter
• Extends from larynx down to the lungs where it splits into
two bronchi
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Bronchi
• The trachea divides into the right and left pulmonary
bronchi.
• Made of rings of cartilage and lined with cilia (little hairs that
move air along)
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Bronchi and Bronchioles
• As the bronchi enter the lungs, they branch off into
smaller tubes called bronchioles
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Lungs - Overview
• Lungs are paired organs in the thoracic cavity; they are
enclosed and protected by the pleural membrane.
• The parietal pleura is the outer layer which is attached to
the wall of the thoracic cavity.
• The visceral pleura is the inner layer, covering the lungs
themselves.
• Between the pleurae is a small potential space, the
pleural cavity, which contains a lubricating fluid secreted
by the membranes.
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Lungs - Overview
• The lungs almost totally fill the thorax.
• The right lung has three lobes separated by two fissures;
the left lung has two lobes separated by one fissure and a
depression.
• Each lobe is divided into smaller sections called lobules.
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Alveoli
• An alveolus (plural is alveoli) is a cup-shaped pouch filled
with fluid called surfactant.
• This is where oxygen and carbon dioxide enter and leave
the blood from the capillaries.
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Histology of Lung Tissue
Photomicrograph of
lung tissue showing
bronchioles, alveoli
and alveolar ducts.
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Blood Supply to the Lungs
• Deoxygenated blood enters
the lungs through the
pulmonary artery (from the
heart)
• Oxygenated blood is
returned to the heart
through the pulmonary
veins
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Physiology of Respiration
• Respiration occurs in three basic steps: pulmonary
ventilation, external respiration, and internal respiration.
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Step 1 = Pulmonary Ventilation = Breathing
• Inhalation, or breathing in, is the first step.
• Lungs expand through muscle contraction, which increases
lung volume and decreases pressure inside the lungs
• Lungs then fill with air
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Expiration
• Expiration (exhalation) is the movement of air out of the
lungs.
• No muscle contractions are involved, this is a passive
process
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Breathing Patterns
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•
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Eupnea is normal variation in breathing rate and depth.
Apnea refers to breath holding.
Dyspnea relates to painful or difficult breathing.
Tachypnea involves rapid breathing rate.
Costal breathing is shallow breathing where the chest
moves up and down.
• Diaphragmatic breathing is deep abdominal breathing.
• Modified respiratory movements are used to express
emotions such as laughing, sighing, and sobbing; or
coughing and hiccupping.
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LUNG VOLUMES AND CAPACITIES
• At rest, a healthy adult averages 12 breaths a minute.
• Lower than normal indicates pulmonary malfunction.
• A spirometer or respirometer measures the volume of air
exchanged during breathing.
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Step 2: External (pulmonary) Respiration
• The exchange of O2 and CO2 between the alveoli and the
blood occurs via passive diffusion.
• The gases flow from where they are MORE concentrated to
where they are LESS concentrated.
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Step 3 = Internal Respiration
• Exchange of gases
between blood & tissues
• Conversion of
oxygenated blood into
deoxygenated
• Oxygen moves from the
blood in capillaries to
cells and tissues.
• CO2 leave cells and
tissues and enters veins.
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Oxygen Transport
• In each 100 ml of oxygenated blood, 1.5% of the O2 is
dissolved in the plasma and 98.5% is carried within red
blood cells, which have hemoglobin.
• Hemoglobin consists of a protein portion called globin and a
pigment called heme.
• The heme portion contains 4 atoms of iron, each capable of
combining with a molecule of oxygen.
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Carbon Dioxide Transport
• Is carried by the blood in 3
ways
– dissolved in plasma
(7%)
– combined with the
globin part of Hb
molecule forming
carbaminohemoglobin
(23%)
– As bicarbonate ions
dissolved in plasma
(70%), this is CO2
combined with
hydrogen ions.
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Respiratory Center
• The area of the brain from which nerve impulses are sent
to respiratory muscles is located in the brain stem.
– The medulla oblongata
– The pons
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EXERCISE AND THE RESPIRATORY SYSTEM
• As muscles contract, they use a lot of oxygen.
• Respiration and heart rate both increase.
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Smokers Lowered Respiratory Efficiency
• Smoker is easily “winded” with moderate exercise
– nicotine constricts terminal bronchioles
– carbon monoxide in smoke binds to hemoglobin
– irritants in smoke cause excess mucus secretion
– irritants inhibit movements of cilia
– in time destroys elastic fibers in lungs & leads to
Emphysema:
• trapping of air in alveoli & reduced gas exchange
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Aging & the Respiratory System
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Respiratory tissues & chest wall become more rigid
Vital capacity decreases to 35% by age 70.
Decreases in macrophage activity
Diminished ciliary action
Decrease in blood levels of O2
Result is an age-related susceptibility to pneumonia or
bronchitis
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Disorders of the Respiratory System
• Asthma
• Chronic obstructive pulmonary disease
– Emphysema
– Chronic bronchitis
• Lung Cancer
• Pneumonia
• Tuberculosis
• Coryza and Influenza
• Pulmonary Edema
• Cystic fibrosis
• Asbestos
• SIDS
SARS
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DISORDERS: HOMEOSTATIC IMBALANCES
• Asthma is chronic airway inflammation and obstruction,
which causes difficult breathing. A common triggering factor
is allergy, but other factors include emotional upset, aspirin,
exercise, and breathing cold air or cigarette smoke.
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DISORDERS: HOMEOSTATIC IMBALANCES
• Chronic obstructive pulmonary disease (COPD) is a type of
respiratory disorder characterized by chronic and recurrent
obstruction of air flow, which increases airway resistance.
– Emphysema is caused by destruction of the alveoli,
caused by smoking, pollution, exercise
– Bronchitis is excessive secretion of bronchial mucus and
a cough. It is caused by smoking, inhaled irritants, and
bacterial infections.
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DISORDERS: HOMEOSTATIC IMBALANCES
• In lung cancer, bronchial epithelial cells are replaced by
cancer cells. Airways are often blocked and metastasis is
very common. It is most commonly associated with
smoking.
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DISORDERS: HOMEOSTATIC IMBALANCES
• Pneumonia is an acute infection of the alveoli. The most
common cause in the pneumococcal bacteria which can
be treated with antibiotics. It is the most common cause of
infectious death in the US.
• Tuberculosis (TB) is an inflammation of pleurae and
lungs produced by the organism Mycobacterium
tuberculosis. It is communicable and destroys lung tissue,
may be treated with antibiotics.
• Coryza (common cold) is caused by viruses and usually
is not accompanied by a fever, whereas influenza (flu) is
usually accompanied by a fever greater than 101oF.
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DISORDERS: HOMEOSTATIC IMBALANCES
• Pulmonary edema refers to an abnormal accumulation of
interstitial fluid in the alveoli of the lungs. It can be caused
by the diet drug Phen-fen.
• Cystic fibrosis is an inherited disease of secretory
epithelia that affects the respiratory passageways,
pancreas, salivary glands, and sweat glands. 5% of white
people are carriers.
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DISORDERS: HOMEOSTATIC IMBALANCES
• Asbestos related diseases develop as a result of inhaling
asbestos particles. Diseases such as asbestosis, diffuse
pleural thickening, and mesothelioma (cancer) may result.
• Sudden infant death syndrome (SIDS) is the sudden
unexpected death of an apparently healthy infant due to
cessation of breathing. Peak incidence is ages two to
four months. The exact cause is unknown.
• Severe acute respiratory syndrome (SARS) is an
emerging infectious disease. It is viral and there is no
vaccine or treatment. Death rate is 10%.
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