Respiratory System Flashcards
Anatomy of upper and lower respiratory tracts
Upper
Nasal turbinates Nares Epiglottis Larynx Oesophagus
Lower
Trachea Carina Primary bronchus Bronchiole Lower lobe Diaphragm
Anatomy of lower respiratory tract
Trachea
Cartilage rings Primary bronchus Root of lung Visceral pleura Cartilage plates Secondary bronchus Tertiary bronchi Smaller bronchi Bronchioles Terminal bronchiole Respiratory bronchiole Alveoli
Anatomy of terminal airways and alveoli
Microscopic air tube
Microscopic blood vessels
Capillaries
Alveoli
Breathing and respiratory
External respiration- is what we call breathing - this occurs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses into the alveolar air
Internal respiratory occurs in the metabolising tissues, where oxygen diffuses out of the blood into the tissues and carbon dioxide diffuses out of the cells and into the blood
Respiratory processes
Neural control - respiratory centres in the brain control inspiration rate and death
Ventilation - air entry to lungs
Perfusion - blood supply to the lungs
Diffusion - oxygen tea spot to RBCs
Why do we need oxygen
Oxidative phosphorylation:
- adenosine triphosphate (ATP) is the universal energy source of cells to facilitate all chemical processes in cells
- ATP is produced through a series of chemical reactions in the inner compartments of mitochondria, the final stages of which require oxygen
The body presses 90 seconds supply of ATP therefore it is necessary to breathe continuously in order to supply enough oxygen for the on going generation of ATP
Tissue viability in anoxia
Brain cell death= 4-5 mins
Myocardium = 5 mins
Kidneys and liver = 10 mins
Skeletal muscle= 2 hours
Anatomical differences
As compared to an adult a child has
A relatively large occiput = flexion of the neck can cause partial obstruction
A relatively large tongue = potential for obstruction
Changing dentition over time = no teeth/ milk teeth/ adult teeth/ loose teeth can be inhaled
Obligatory nose breathers under 6 months of age, risk of apnoea with nasal blockage
Anatomical differences
Narrow nasal passage= smaller airways = greater resistance to airflow, exacerbated by any secretions
Frequently enlarged tonsils/ adenoids= increased resistance to airflow and potential obstruction
Sharp angle between orophayrnx and glottis = enables young babies to breath and feed at the same time
Anatomical differences
Smaller airways diameter= any obstruction/ inflammation causes greater resistance to flow and so more sever distress ( infants are extremely vulnerable to atelectasis and exploratory wheeze)
Airway walls that are less rigid = tendency to collapse when in distress giving greater resistance to air flow
Thicker alveoli walls at birth = decreases the efficiency of gas exchange
Anatomical differences
Fewer alveolar numbers (alveolar clusters develop over the first 8 years of life) less efficient gas exchange
Ribs that are more horizontal = lessening the chest wall movement and tidal volume
Rib cartilage that is more compliant = less outward recoil and tidal volume
Weaker intercostal muscles = less able to lift the rib cage up and forward and so tidal volume decreases
Surfactant
Action of surfactant
- reduces water surface tension
- prevents collapse on expiration
Produced by type 2 alveolar pneumocystis
- 22-24 weeks production begins
- 32-36 weeks sufficient concentration present
Production of surfactant is induced by
- glucocorticoids eg cortisol
- catechilamines eg adrenaline
Acute respiratory failure
An acute clinical situation in which alveolar ventilation fails to maintain arterial blood gasses at physiological values
NB there may be acute respiratory failure on top of existing chronic respiratory failure
Cause of acute respiratory failure
Drug overdose, spinal cord injuries, stroke
Trauma, injury affecting ribs and or lungs
Infection, pneumonia, croup, epiglottitis, bronchiole ‘tis
Airway obstruction, foreign body, asthma, allergic reaction
Burns inhalation of hot or corrosive fumes
Vulnerability to respiratory tract infections in children
At birth
- immunologically immature
- has benefit of placental transfer of maternal IgG and IgA
First six months
-anatomical risk eg narrower bronchial tree
-environmental risk include
Exposure to tobacco smoke
Formula feeding- on immunological advantages
Child care/siblings - infection
Poor socio-economic status and housing
Vulnerability persists, but to a lesser degree during first 7-8years of life
Clinical assessment of ARF
Clinical signs and symptoms of ARF include
Confusion, sleeping and loss of consciousness
Dyspnoea- subject sensation of difficult or laboured breathing air hunger, shortness of breath, feeling like you can’t get enough air
Cyanosis- bluish colour on your skin, lips, and fingernails
Increased work of breathing