The Respiratory System Flashcards
Where is the parietal pleura?
It lines the ribcage.
Where is the visceral pleura?
It adheres to the lung surface.
During inspiration which direction does the diaphragm move?
It moves downwards increasing thoracic volume.
Factors that lead to increased ventilation
- Increased CO2 in the blood
- Decreased 02 in the blood
- Lowered pH level in the blood.
How much anatomical dead space is there in the lungs?
About 150ml.
How is minute volume calculated?
Respiratory rate x tidal volume
The volume of air that can be exhaled after normal exhalation is….
Expiratory reserve volume
Contraction of the diaphragm causes….
Inspiration of air.
Lung compliance
Determines how easy it is for inspiration to occur. Low compliance makes is more difficult while high compliance makes it easier.
Tidal Volume
The volume of air that passes in and out of the lungs with each breath at rest.
Chemoreceptors
Important in regulating breathing.
Name the three parts of the pharynx
Nasopharynx - posterior to the nasal cavity
Oropharynx - posterior to the mouth
Laryngopharynx - above the layrnx
Functions of the larynx
- Produces sound
- Protects the airway
- Passageway for air during breathing
Main Functions of the Respiratory System
- Enable oxygen to move from the air into the blood
- Enable carbon dioxide to move from the blood to the air
- Metabolism of some compounds
- Filtration of toxic materials from the circulation.
- To act as a reservoir for blood.
Function of the Epiglottis
Blocks the trachea during swallowing to prevent food from entering the lungs.
Function of the nasal, pharyngeal and laryngeal cavities
To filter, heat and moisten air that passes through it. They also produce mucous secretions to trap impurities.
Pleura
Made up of the visceral pleura (covers the lungs) and the parietal pleura (lines the ribs). Pleural spaces between these two layers is filled with serous lubricating fluid allowing the lungs to expand and deflate with little frictional resistance.
What lines the trachea?
Ciliated epithelium which transport mucus and trapped particles upwards toward the epiglottis for swallowing.
Name the divisions of the bronchi
- Trachea
- Right & Left Primary Bronchi
- Secondary Bronchi
- Tertiary Bronchi
- Terminal Bronchioles (no alveoli)
- Respiratory Bronchioles (occasional alveoli)
- Alveolar ducts (completely lined with alveoli)
Bronchioles
Smallest airways without alveoli. Take no part in gas exchange and are referred to as anatomical dead space. Encapsulate about 150ml of air.
What does the diaphragm do at rest?
It contracts and pulls downward to increase the thoracic space so air can flow in.
Function of the external intercostal muscles
Aid expansion of the chest when increased respiratory effort is required. Pull the ribs upwards and outwards increasing thoracic space.
Accessory Muscles
Include:
- External intercostal muscles (lift ribs up and out)
- Scalene Muscles (lift the first 2 ribs)
- Sternomastoids (raise the sternum)
All work to increase the thoracic cavity.
What do the lungs do during expiration?
They passively recoil as they are very elastic. Inspiratory muscles rest.
Compression of air in the lungs occurs making higher pressure inside the lungs than out causing expiration.
Active expiration
Occurs during exercise.
- abdominal wall contracts pushing the diaphragm upwards
- Internal intercostal muscles act pulling the ribs down and in.
Internal intercostal muscles
Pull the ribs down and in causing expiration.
Compliance
Refers to how much effort is required to expand the chest wall and inflate the lungs.
Normally the lungs are easy to inflate and said to have a HIGH compliance.
Airway resistance
Resistance posed to airflow by the airways.
Normally low so pressure required to move air through the airways is usually small.
Surface Tension of Alveolar Fluid
Line the surface of the alveoli to permit gas exchange.
Should cause the alveoli to collapse upon expiration.
Alveoli produce surfactant which reduces surface tension preventing alveolar collapse.
Surfactant
Produced by alveoli to reduce surface tension and prevent collapse of alveoli during expiration.
Total lung volume
6 liters
Tidal Volume
Amount of air that moves in and out of the lungs at each inspiration and expiration. This is approximately 1/2 a liter at rest.
Reserve volumes
Maximum volume that can be inspired or expired above the tidal volume.
Vital capacity
Maximum volume that can be exhaled
Residual volume
Gas which stays in the lungs after maximum expiration (about 1.2 liters).
Includes the air in the anatomical dead space and the air required to keep alveoli open.
Minute volume
Total volume of air inhaled and exhaled each minute.
Minute volume = tidal volume (L) x respiratory rate (breaths/min)
Negative feedback elements used in breathing
- Sensors - gather information
- Control Unit - analyzes information and initiates appropriate response.
- Effectors - produce the required change
Chemoreceptors
Respond to changes in oxygen, carbon dioxide and hydrogen (pH) levels in the blood.
Stretch receptors in the lungs
Detect over and under stretching of the lungs to reduce or increase respiratory rate.
Function of the Autonomic Nervous System
Uses chemoreceptors to detect changes in the oxygen, carbon dioxide and nitrogen levels in the blood.
Stretch receptors detect the expansion of the chest walls and relay messages to cause inspiration and expiration as required and prevent damage.
Nerve signals from the hypothalamus and cerebral cortex can cause the respiratory centres to speed up or slow down.
Chemical irritants can be detected by the ANS causing coughing or sneezing to rid the body of these substances.
What is Asthma?
A respiratory condition characterised by reversible attacks of chronic obstruction with wheezing.
Can be either intrinsic or extrinsic.
Extrinsic Asthma
Affects children and young adults.
Caused by a hypersensitivity to airborne allergens such as dust mite faeces, tobacco smoke, pollens or animal dander.
Pathophysiology of Extrinsic Asthma
Inhaled irritants lead to:
- airway epithelial shedding
- inflammatory mucosal oedema
- smooth muscle contraction
- increased secretions
This results in:
- bronchial wall inflammation
- narrowed airways
- hyper-reactivity
Intrinsic asthma
- Later onset - young adults and adults
- may be related to allergens or family history
- can be triggered by viral infections
Clinical symptoms of asthma
- cough - dry or productive
- breathlessness
- wheeze
- chest tightness, discomfort, pain
- symptoms worse at night or after exercise
- symptoms worsen by respiratory tract infection & chronic exposure to external factors
Management of Asthma
Step 1: Inhaled Short Acting Bronchodilator
Step 2: Inhaled Corticosteroids at a low does
Step 3: Increase inhaled steroid or add long acting bronchodilator
Step 4: Add on Therapy
Step 5: Long term oral steroids
Management of Acute Asthma
- Lots of O2 at a high dose
- Nebulized bronchodilators with the 02
- Prednisolone (a corticosteriod)
- Avoid sedatives (these will suppress the respiratory system)
- Give IV magnesium sulphate
- Nebulizers ever 15-30 minutes
Prednisolone
A corticosteroid used for the treatment of asthma that reduces inflammation. Can be given orally, inhaled or by injection.
Clinical manifestations of life threatening asthma
- Peak Expiratory Flow Test less than 33%
- Oxygen sats below 92%
- Silent chest/poor respiratory effort
- Bradycardia/hypotension
- Exhaustion
COPD
Characterized by an airflow obstruction which is usually progressive and not fully reversible and does not change over a period of months.
It is predominately caused by smoking.
Encompasses both chronic bronchitis and emphysema.
Pre-disposing factors for COPD
- Smoking
- Occupational Exposure (dust, smoke from wood or coal fires etc)
- Genetic
- Social deprivation (lifestyle and poor diet can worsen conditions)
- Age
- Air pollution (environmental or 2nd hand smoke)
- Deficiency in alpha-1 antitrypsin.
Chronic Bronchitis
Condition of mucous hypersecretion combined with loss of muco-ciliary clearance resulting in pulmonary obstruction.
Acute Bronchitis
Sudden onset which usually appears after a respiratory infection (a cold) and can be caused by either a virus or bacteria.
Hypercapnia
High amounts of carbon dioxide circulating in the blood.
Hypoxia
Reduced oxygen reaching the tissues.
Hypoxemia
Abnormally low concentration of oxygen in the blood.
Initial assessment of patient with COPD
- Visual - cyanosis, perfusion
- Vital signs - Respiratory rate, rhythm, depth
- Breathing sounds
- Use of accessory muscles
- Breathlessness - all the time or on exertion?
- Sputum appearance - check for infection
Treatment of Acute COPD
- A-E assessment
- Low level oxygen therapy - watch out for hypoxic drive!
- Good positioning to assist breathing
- Nebulizer with bronchodilator (or sub cut)
- IV fluids (to counteract dehydration due to tachypnoea)
- IV steroids to reduce bronchospasm & reduce inflammation
Long Term Management of COPD
- Inhaler/nebulizer w/bronchodilators and steroids
- Antibiotic if infection is present
- Low dose oxygen therapy
- Educating patient and family about condition
- Dietary advice
- Physiotherapy
- Aids at home/assistances with activities of DL
- Family support
Pulmonary Emphysema
Destruction of alveoli walls and elastic fibers. Permanent enlargement of alveoli and destruction of walls of terminal bronchioles. Chronic inflammation of airways due to continued inhalation of irritants.
Hypoxic hypoxia
Poor pulmonary oxygen transfer
Stagnant hypoxia
Poor blood flow
Anaemic hypoxia
Poor oxygen carriage
Histotoxic hypoxia
Sepsis, cyanide in blood.
Causes of hypoxia
- Hypoventilation
- Diffusion defects in alveoli
- Ventilation-perfusion mismatch
- Shunts
Shunts
Blood bypasses alveolar beds and gets no chance for oxyenation
Why are high levels of oxygen dangerous for some respiratory patients?
Patients with underlying respiratory disease like COPD develop a sensitivity to falling oxygen levels in the blood rather than raised carbon dioxide levels. Giving higher levels of oxygen will reduce the stimulus to breathe and lead to carbon dioxide retention. This can lead to respiratory acidosis.
What is residual volume of the lungs?
The amount of air left in the lungs after maximum expiration. Approximately 1.2 liters.
Pathophysiology of Pneumonia
Bacteria, fungus or a virus cause an infection in the lung which causes alveolar inflammation and filling of the alveoli with fluid and poor gas exchange.
