Respiratory System Flashcards
What are the functions of the respiratory system?
resp function:
- gas transport for metabolism
- move o2 from air into pulmonary blood
- clearance of co2
non-resp function
- lungs receive 100% of cardiac output from right heart
- filter blood, chemical processing, maintenance and defences (first line)
- facilitate venous return
Definition of respiration vs ventilation?
respiration: interchanges of gases between the atmosphere and the cells of the body
ventilation: transport of air to and from the lungs
What are the 5 steps to overall gas transport?
- ventilation: movement of bulk airflow, delivering air to the respiratory zone where gas exchange occurs
- gas exchange/lung diffusion: gas exchange btwn resp zone and blood - O2 moves across to blood and RBCs; reverse for CO2
- circulation/transport: blood to/from tissues, requires adequate function of the pulmonary and systemic circulations
- tissue diffusion: erythrocyte/plasma to/from tissue cells
- internal respiration: metabolism using O2 and producing CO2
What are the five airways?
- nasal/oral cavities
- pharynx and larynx
- trachea
- bronchi
- bronchioles
What airway connects to alveoli?
bronchioles
What are four functions of the airways?
- delivering gas to the respiratory zone
- air warmed to core body temperature
- gas humidification (saturation with vapor to prevent dehydration of the respiratory epithelium in alveoli)
- filtration/cleansing: prevents foreign objects/microorganisms to enter the lungs (reduces risks of injury and infection)
What are the three structures of the nasal/oral cavities?
- inner surface - mucous membrane that warms/humidifies air
- hair in nostrils (filter)
- epithelium contains ciliated cells and mucus cells (goblet) which trap foreign objects and move the mucus towards the pharynx
What is the function of the pharynx
connection between nasal/oral cavity and the larynx
What is the function of the larynx?
connects pharynx and the trachea: glottis and epiglottis (cartilage that prevents food to enter the trachea)
Which airway structure contains the vocal cords?
larynx
What is the trachea kept open by?
cartilage rings
What is a characteristic of the trachea?
inner surface lined with ciliated and mucus cells, mucus traps particles, and coordinated cilia movements push the trash back towards pharynx
What are some characteristics of the bronchi?
- possess cartilage plates to maintain shape
- branch off into narrower tubes with less cartilage
What are the primary bronchi?
part of the bronchi, the very beginning where the bronchi split into two tubes into each lung
Do bronchioles have cartilage?
lack cartilage - depends on lung recoil to maintain potency (possess smooth muscle)
Do bronchi and bronchioles have ciliated and mucus cells?
yes
Why doesn’t the bronchi need to be as sturdy as the trachea?
ribs protect thoracic cavity
What is a bronchiospasm?
muscle layers that control constriction of bronchiole can compress it when inflammed
Does airway cross sectional area increase or decrease as you move from the trachea to the respiratory zone?
increases dramatically moving from trachea to resp zone
- geometric increase in small airways
- reduces veocity of airflow to zero
- movement of gas through diffusion only
What are the two methods of airway clearance?
- cilia and goblet cells work to move thin sheets of mucus from lower parts of the lungs to the throat region
- defensins: airway defensin destroys bacteria
What happens in the airways during inflammation?
accumulation of mucus and pus in the trachea caused by cells inability to move it up creates restriction of airflow/turbulence
Where are alveoli located?
clusters around terminal bronchioles
What are alveoli formed by?
single layer of epithelial cells
What are alveoli surrounded by?
capillary network
How many layers of cells are air and blood separated by?
two layers (epithelium and endothelium)
What do type 2 epithelial cells produce?
fluid (surfactant which reduces surface tension) - maintains opening of the alveoli
What happens if small particles reach the alveoli?
phagocytized by macrophages
What are the two types of epithelial cells?
type 1: squamous
type 2: epithelial
type 1 becomes type 2 eventually
What is the thoracic cavity?
space within the thoracic cage between: thoracic vertebras, ribs and intercostal muscles, sternum
What is the diaphragm?
separate from the thoracic and abdominal cavity, sheet of skeletal muscles and tendon
What is the mediastinum?
divide the thoracic cage in 2 halves (from spine to sternum)
connective tissue containing vessels, nerves, trachea, esophagus and the heart
each lung fills 1 half
What is the pleural membrane?
cover lungs, wet epithelium, contains parietal and visceral pleura
What is the intrapleural space?
filled with fluid, lubrication for friction free movements
What is a rule about ventilation?
flows from high to low pressure
resistance of flow (R) due to friction of air particles with each other and with the ducts
What is the formula for flow?
F = change in P/R
What is the relationship between R and deltaP?
if R increases, deltaP increases
if R decreases, deltaP decreases
What controls deltaP?
compression/expansion of the lungs by resp muscles
Inspiration vs expiration passive or active mechanisms?
Inspiration - active mechanism
Expiration - passive mechanism
What are the steps to inspiration?
diaphragm contracts -> expands thoracic volume -> creates negative pressure -> lung expands -> increase in alveolar volume -> negative pressure gradient facilitates flow down airways
What are the steps to expiration?
end of inspiration -> inspiratory muscles relax -> allows lung to spontaneously recoil -> increase pressure in alveoli -> create pressure gradient from alveoli to atmosphere
At rest, which muscle of the respiratory system is the most important muscle?
diaphragm
What is Boyles law of gases?
for a gas at a set temperature, pressure and volume are linked P1V1 = P2V2
What is the relationship between V and P?
- if volume increases pressure decreases
- if volume decreases pressure increases
What happens to the P during inspiration and expiration?
Inspiration: Palveolar < P atmosphere
- propels air through the airway until P alveolar = P atmos
Expiration: P alveolar > P atmosphere
- airflow outward until equilibrium reached
What are some special cases of pressure movement in the airways?
horses: end of expiration active - beginning of inspiration passive
locomotion (walk/run): more than just diaphragm and intercostal muscles, muscles take active part in expiration to speed it up, galloping synchronization with breathing
diving mammals: voluntary apnea, strong conducting airways, when under water, compressed gas pushed towards airways (no gas exchange) - prevents gas entry into blood
What are two factors influencing ventilation?
airway resistance
lung compliance
alveolar surface tension
Where does airway resistance occur mostly?
nasal cavity
Does more turbulence create more airway resistance?
yes
What influences airway resistance in the anatomy of airways?
reduced diameter with branching increases the resistance, parallel branches results in increased SA which compensates for increased resistance
as well as constriction of smooth muscle in bronchioles
What controls the constriction of smooth muscle in the bronchioles?
ANS, sympathetic relaxes cells and parasympathetic contracts cells
What is lung compliance?
ability of the lung to distend followed by the ability to recoil