Respiratory system Flashcards
What are the functions of the respiratory system do?
- warming, humidifying and filtering air
- olfaction (special sense smell)
- Protection & defence: managing inner ear pressure, site of immune defence
- phonation (speech)
- pulmonary ventilation
- maintains blood pH by regulating acid-base balance of blood
- endocrine (hormone) functions
- gas exchange between lung and blood
What is the upper and lower respiratory tract made of?
Upper: Nose, pharynx (throat) nasopharynx (balance air pressure), larynx
Lower: Trachea, airways, lungs
What is the pleura?
Each lung is covered by a sac of sous membrane. the serous secretes serum called pleura fluid.
So, is a thin layer of tissue covering lungs.
- Lung surface is covered by visceral pleura
- Thoracic cavity is lined by parietal pleura
The fluid creates surface tension so that lungs expand when ribcage and diaphragm expand.
It lubricates expansion and contraction of lungs without lungs getting wet
Trachea=
- Warms and humidifies air
- Is a windpipe that extends from larynx to the lungs.
- Branches into L and R primary bronchi. The carina helps with branches, it is the dividing point.
- Is kept open by C- shaped cartilage to support and keep airway open.
- Lined by columnar epithelium
- Goblet cells and mucous glands produce mucous
What does the hyaline cartilage in the trachea do?
Gives capacity to narrow the cross section of the trachea
Trachealis muscle=
contracts during cough reflex to help speed up air and regulate the flow of air through the trachea. So it clears the space of the trachea.
Mucociliary escalator=
within wall of trachea, transports mucus and foreign particles towards upper airway. Keeps trachea/ airways clear
Hilium of the lung=
What connects lungs to their supporting structures and where pulmonary vessels enter/ exit lungs.
What are the lobes of the lungs divided by?
Fissures, both horizontal fissure and oblique fissures.
What are the three lobes of the lung?
- superior lobe
- middle lobe
- inferior lobe
What supplies each segment of the lungs?
Tertiary bronchi
What are bronchioles?
As bronchiole branches divide, they get smaller. Each smaller branch is known as a bronchiole. They:
- Loose their cartilage
- Smooth muscle increases
- Cilia and goblet cells decrease
Pulmonary arteriole vs pulmonary venule
Pulmonary arteriole= bringing in deoxygenated blood
Pulmonary venule= taking oxygenated blood to the hart
What is in the respiratory zone?
Respiratory bronchioles, alveolar ducts, alveoli.
(In the lower respiratory tract)
Alveoli=
They are air sacs at end of bronchioles. Where lungs and blood exchange oxygen & carbon dioxide.
They have a single layer of squamous epithelium.
Are supported by loose, elastic, connective tissue (fibroblasts) containing:
- Macrophages
- Fibroblasts
- Nerves
- Blood vessels, dense capillary network
- Lymph vessels
Have surfactant (molecules) which:
- Are a surface active agent
- Decrease surface tension of fluid making it easier to inflate lungs
- Prevent alveoli from collapsing
What is the microscopic structure of alveoli?
- Type I alveolar cells= squamous cells making up wall of alveoli
- Type II alveolar cells= help repair lining of alveoli and secrete surfactant.
- Macrophages= pick up particles/ pathogens to help with the immune response
- fluid layer on alveolar surface is required
How is debris removed?
Large particles= nasal hairs & mucus of upper respiratory tract
Medium particles= mucus of bronchi, bronchioles and mucociliary escalator
Small particles= alveolar macrophages
But, not all particles are removed, can cause: smokers lung, carbon tattooing
Gas transport at respiratory membrane is dependant on:
- partial pressure
- thickness of respiratory surface
- area of respiratory surface
- ventilation/ perfusion coupling
- temperature of fluids/ tissues
- gas solubility
Partial pressure=
total pressure in a mixture of gases equals sum of partial pressures of each individual gas- daltons law
What is total air pressure made up of?
nitrogen, oxygen and carbon dioxide
Ficks law=
rate of gas transfer is proportional to:
- tissue area
- diffusion coefficient of the gas
- difference in partial pressure either side of membrane
But the rate of gas transfer is inversely proportional to:
- thickness of the membrane
V/ Q coupling
Alveolar ventilation (V)= volume of air which takes place in gas exchange
Perfusion (Q)= blood that reaches alveoli via capillaries.
Both can effect gas exchange- an optimal balance is required
Local auto regulation in blood vessels=
if there is poor ventilation, blood vessels vasoconstrict and redirect blood flow to areas of better oxygen.
If there is good blood flow, blood vessels vasodilate to accept more blood
Boyles law=
Pressure is inversely proportional to volume, so explains why air goes in/ out of lungs when we change our chest volume.
So, as volume decreases the pressure increases, as volume increases the pressure decreases
It is good to understand Boyles law because it helps us understand the relation between pressure and volume in the lungs when breathing.