Quiz 2 Flashcards
Nasal Cavity and the Mouth
Air is inhaled and enters the body through the mouth and nasal cavity
- Warmed up through the process
Parts of the Respiratory System
Conducting Airways:
- Through which the air moves between the lungs and atmosphere
(nasal passages, mouth, nasopharynx, larynx and tracheobronchial)
Respiratory Airways:
- Lungs are the functional structures of the res system
- Lobules are the smallest functional unit of the lungs, consisting of the res bronchioles, alveoli and pulmonary Caps, responsible for gas exchange
Trachea Function
- Air passes down the trachea
- Trachea is a long tube connecting the mouth and nasal cavity of the rest of the Res system
Bronchus Function
- Trachea branches off into two bronchi
- One bronchus enters each lung
Bronchioles
- Each bronchus divides into smaller tubes called bronchioles which the air passes through
Alveoli
- Alveoli are located at the end of each bronchiole
- Alveoli are air sacs which facilitate gas exchange
- There are millions of them in the lungs
- Alveolar macrophages are responsible for the removal of offending particles from the alveoli
Alveoli Features
- Thin walls to reduce the distance for diffusion
- Walls are only one cell thick
- Have a large surface area which is moist so gases can dissolve and diffuse across
- Surrounded by caps, so alveoli have a rich blood supply
Gas Exchange
- Inhaled O2 diffuses from the alveoli into the blood
- Inhaled Nitrogen cannot diffuse so it doesn’t enter the blood stream
- CO2 diffuses from the blood into the alveoli to be exhaled
Pleura
- Double-layered membrane that surrounds each lung
2 Parts: - VISCERAL = adheres to the lung surface
- PARIETAL = lines chest wall
Pleural Cavity
Thin space between both pleura
- Thin film of serous fluid that reduces friction during respiration
- Potential space for excess fluid or inflammatory exudates to accumulate
Ventilation
Movement of gasses in and out of lungs
Inspiration
Chest cavity EXPANDS
Expiration
Chest cavity becomes SMALLER
Lung Tissue Composition
1) Elastin
2) Collagen
When elastin fibres are replaced by scar tissue, the lungs become stiff and non-compliant (not as stretchy as before)
Pulmonary Congestion and edema also result in a reversible decrease in pulmonary compliance
Pulmonary Compliance
Extent to which lungs expand
Pulmonary Function Tests
Spirometry = physiological test that measures the ability to inhale and exhale air relative to time
- Diagnostic test of several common respiratory diseases
- Test for FVC, FEV-1.0, % of FVC)
Forced Vital Capacity (FVC)
Max amount of air that can be rapidly and forcefully exhaled from the lungs after full inspiration
Forced Expiratory Volume in 1 second (FEV-1.0)
Volume of air expired in the first second of FVC
% of FVC
Volume of air expired in the first second, expressed as a percentage of FVC
Lung Perfusion
- Flow of blood through blood vessels in the lungs
- Essential for the exchange of O2 and CO2
- Blood flows through the lungs, it picks up O2 from the air we breathe and releases CO2 to be exhaled
Ventilation-Perfusion Ration (V/Q)
- Compares the amount of air that gets into the lungs (ventilation) to the amount of blood flowing through the lungs (perfusion) to assess how well the lungs are bringing in O2 and getting rid of CO2 (should be almost even = 1.0)
- Healthy lungs = V/Q ratio is typically around 0.8 (slightly more blood flow than air reaching the alveoli)
- Conditions like PNEUMONIA make it hard for air to get in and BLOOD CLOTS (PULMONARY EMBOLISM) in the lung can block blood flow affect V/Q ratio and overall lung function
What Affects Gas Diffusion?
- Characteristics of gas (eg CO2 diffuses 20x faster than O2)
- Concentration of gas (differences in partial pressure on either side of the membrane)
- Thickness of alveolar-capillary membrane
- Surface area of lung tissue (diseases destroy lung reduce surface area and diffusion)
Arterial Blood Gases
- Blood gas measurement are used to determine the partial pressure of O2 (PO2) and CO2 (PCO2)
- Arterial blood is preferred for measuring blood gases because venous levels of O2 and CO2 reflect the metabolic demands of the tissues rather than the gas exchange function of the lungs
NOT AS IMPORTANT TO KNOW NOW (WILL LEARN MORE NEXT SEMESTER)
Normal Values:
pH = 7.35-7.45
PaO2 = 80-100mmHg
PaCO2 = 35-45mmHg
HCO3 = 22-26mmol/L
BE = -2 - +2
SaO2 = 94-100%
Respiratory Acidosis
Respiratory Alkalosis (CO2 is lower)
Innervation
Lungs innervate by the sympathetic and parasympathetic divisions of the autonomic NS
**PARASYMP NS:
(Cholinergic receptors)
- Stimulation leads to bronchial constriction and increased glandular secretions
**SYMP NS:
- B2 Adrenergic receptors
- Stimulations cause airway relaxation, blood vessel constriction and inhibition of glandular secretion
Lung Diseases
Restrictive Lung Disease
Obstructive Lung Disease
Airway Disease
Lung Tissue Disease
Lung Circulation Disease
Restrictive Lung Disease
Lung tissue or chest muscles can’t expand enough
- Creates problem with air flow because less lung volume
Eg) Pulmonary Fibrosis
Obstructive Lung Disease
Air has trouble flowing out of the lungs because of airway resistance
= slower flow of air
Eg) Asthma, chronic bronchitis, emphysema, COPD
Asthma Defintion
Chronic inflammatory disorder of the airways (NOT autoimmune) that causes episodes of airway obstruction, bronchial hyper-responsiveness, airway inflammation and sometimes airway remodelling
- Muscles tighten, airways swell, Mucus clogs the airways, lungs have difficulty moving in and out
- Inflammation + pro-inflammatory mediators activating further inflammation
- Mast cell degranulation
- MORE BREATHING ISSUE THAN MUCUS ISSUE (COPD is more Mucus)