Florida University: Chapter 20-31| NUR 3125Med-Surg Exam 3,100% CORRECT
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NUR 3125
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NUR 3125
Florida University: Chapter 20-31| NUR 3125Med-Surg Exam 3
Chapter 20: Assessment of Respiratory Function
Purpose of the respiratory system
● Deliver oxygen to the body, expels carbon dioxide from the body
○ Works with the circulatory system
● Upper respiratory system: warms and fill...
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Florida University: Chapter 20-31| NUR 3125Med-Surg Exam 3
Chapter 20: Assessment of Respiratory Function
Purpose of the respiratory system
● Deliver oxygen to the body, expels carbon dioxide from the body
○ Works with the circulatory system
● Upper respiratory system: warms and fills air
○ Nose: serves as passageway, filters impurities, humidifies and warms air
○ Sinuses and nasal passages
■ Paranasal sinuses: lines with mucosa and ciliated pseudostratified
epithelium; serve as resonating chamber in speech and are a
common site for infection
● Frontal, ethmoid, sphenoid, maxillary
● Drain into the nasal cavity via ducts
○ Pharynx (throat): connects nasal and oral cavities to larynx
■ Nasopharynx: posterior to the nose and above the soft palate
■ Oropharynx: houses the tonsils
■ Laryngopharynx: extends from hyoid bone to cricoid cartilage
○ Tonsils and adenoids chain of lymph nodes: guard the body from invasion by
orgasms entering the nose and throat
○ Larynx: connect pharynx and trachea, is the voice box and therefore major
function is vocalization but protects lower airway from ferign substances and
facilitates coughing
■ Epiglottis: covers opening to larynx during swallowing
■ Glottis: opening between vocal cords and larynx
■ Vocal cords: ligaments that produce sound, located in lumen of the larynx
■ Thyroid cartilage: largest cartilage structure, forms part of adam's apple
■ Cricoid: complete cartilaginous ring around larynx, below thyroid cartilage
■ Arytenoid cartilage: used in vocal cord movement w/ thyroid cartilage
○ Trachea: windpipe, smooth muscle with c-shaped rings of cartilage at
regular intervals that give it structure and prevent collapse; passage
between larynx and main stem bronchi
● Lower respiratory system: accomplishes gas exchange
○ Two lungs
■ Left: 2 lobes
■ Right: 3 lobes
○ Pleura: serous membrane that covers the lungs; visceral and parietal; permit
smooth motion of the lung expansion in the thoracic cavity with lubrication
○ Mediastinum: middle of the thorax between pleural sacs; contains all the
, thoracic tissue outside of the lungs
○ Bronchi
■ Lobar bronchi: split into lobes of the lungs
● Segmental bronchi: facilitate postural drainage
○ Subsegmental bronchi
■ Bronchioles: no cartilage, depend on alveolar pressure
and smooth muscle recoil; contain submucosal glands
that cover the inside lining of the airway
■ Lined with cilia that move mucus and foriegn substances back into the larynx
○ Alveoli: where gas exchange takes place via diffusion
■ Alveolar capillary membrane
■ Alveolar cells
● Type 1: 95% of surface, barrier between air and alveolar surface
● Type 2: 5%, produce Type 1 cells and surfactant
● Alveolar macrophages: ingest foreign matter
■ Surfactant: keep surface tension low and
improves lung function Function of the respiratory system
● Oxygen transport: transported by circulating blood; oxygen diffuses through capillary
wall into interstitial fluid, then into cells to be used for cellular respiration
, ○ Perfusion: arterial venous circulation that fills pulmonary capillaries with blood
■ Influenced by alveolar pressure; pulmonary capillaries are between alveoli
and when alveolar pressure is high the capillaries are squeezed, if
squeezed too much it’s pulmonary hypertension
○ Oxygen diffuses from areas of high partial pressure to areas of low partial pressure
■ Transported to the cells by combining with hemoglobin proteins in
RBC; process called oxyhemoglobin
● Respiration: process of gas exchange between atmosphere lungs, lungs and the blood,
blood and cells/tissue
○ Pulmonary diffusion: process by which oxygen and carbon dioxide are
exchanged from areas of high to low concentration at air-blood interface
through alveolar membrane
■ Happens without difficulty in adults because of differences in
concentration; large and thin surface area of alveolar membrane is ideal for
diffusion
○ Pulmonary perfusion: actual blood flow through pulmonary vasculature
■ 2% of blood from R.V. is sent to left side of heart without participating in gas
exchange
■ Low pressure system, pulmonary artery is 20-30mm sys/ 5-15 dia
■ Circulation at apex of lungs is poor when upright
○ Carbon dioxide diffuses across the alveolar-capillary membrane more easily
than oxygen; is the end product of metabolic combustion
○ Oxygen in capillaries of lungs is lower than in the alveoli, which leads it to
diffuse into the blood from the alveoli
● Ventilation: the movement of air in and out of the body
○ Thoracic cavity is an airtight chamber, the diaphragm is at the floor
○ Inspiration: contraction of the diaphragm and contraction of the external
intercostal muscles increases space and creates negative pressure to inflate
airways and expand lungs
■ ⅓ of respiratory cycle
○ Expiration: relaxation of the diaphragm and external intercostals increases
pressure causing air to escape, deflation, and recoil of the lungs
■ ⅔ of respiratory cycle
○ Lung volume and capacities Table 20-1
■ Tidal volume: volume of air inhaled and exhaled in one cycle; about 500mL
● May not vary even with severe disease
■ Inspiratory reserve: maximum volume of air that can be inhaled after normal
inhalation; 3000mL
■ Expiratory reserve: maximum volume of air that can be exhaled forcibly
after normal exhalation; 1100mL
, ● Decreased with restrictive conditions like obesity, ascites, and
pregnancy
■ Residual volume: amount of air in lungs after expiratory reserve is exhaled;
1200mL
● Decreased w/ obstructive disease
■ Vital capacity: maximum volume of air exhaled from maximum inspiration;
4600mL
● VC = TV+IRV+ERV
● Can decrease in neuromuscular disease, fatigue, atelectasis,
pulmonary edema, COPD, obesity
■ Inspiratory capacity: maximum inhaled after normal expiration; 3500mL
● Decrease in restrictive diseases
■ Functional residual capacity: normal volume after normal expiration;
2300mL
● FRC = ERV +RV
● Increased with COPD, decreased in ARDS and obesity
■ Total lung capacity: volume of air in lungs after maximum inspiration;
5800mL
● TLC = TV + IRV + ERV + RV
● May decrease with restrictive diseases such as atelectasis and
pneumonia, increase w/ COPD
● Ventilation-perfusion ratio: adequate gas exchange depends on balanced V/Q ratio,
impalances ratio results in shunting of the blood and hypoxemia
○ Supplemental oxygen may eliminate hypoxemia
○ Imbalances: chart 20-2
Inspiratory and expiratory center is in the medulla and the pons controls the rate and depth
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