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.
Explain pulmonary ventilation (breathing)
- Chest volume changes
- Changes in intrapleural pressure
- Changes in intrapulmonary pressure
- Flow of air down the pressure gradient
Inspiration vs expiration (relaxed)
Inspiration is an active process that requires energy. Costal cartilage stores energy as they are deformed
Expiration is a passive process that doesn’t require energy
What muscles are involved in forced inhalation?
Forced inhalation is where the inspiratory muscles are assisted by accessory muscles during ‘exercise’ to breathe in more forcefully than normal.
neck muscles- sternocleidomastoids, scalenes
chest muscles- pectoralis minor
spinal muscles- erector spinal
What muscles are involved in forced exhalation?
This combines huffing with breathing control.
Transverse abdominals
Rectus abdominus
Latissimus dorsi
internal intercostal cavity
Innermost intercostal mucles main roles=
Stiffening the chest wall during breathing and forced exhalation
What can loading/ unloading be affected by?
- molecular conformation
- availability of H+
- Availability of CO2
- Availability of O2
- Temperature
Venous reserve=
capacity to extract oxygen from the blood as it flows through muscle. Chemical BPG promotes unloading of the oxygen.
Bohr effect=
This happens in tissues for the transport of gases in blood.
Donation of H+ to promote release of O2. So:
- A rise in PCO2
- Increase in H+ ions and lower pH
- Both these result in release of O2 from haemoglobin (RBC that carries oxygen)
gas exchange is adjusted to metabolic needs of the body because of these effects:
- Bohr effect
- Biphosphoglycerate (BPG)
- Partial pressure of oxygen
- temperature
CO2 is carried as:
plasma, carbaminohaemoglobin, bicarbonate
What is breathing affected by?
- resistance of airway
- elasticity of lung tissue
- obstruction to flow
- chest wall compliance
Haldene effect=
This happens in lungs for the transport of gases in blood.
Binding of o2 on haemoglobin promotes release of co2 release
factors affecting airflow
- pulmonary compliance
- airway resistance
- alveolar surface tension
compliance=
measure of ease of expansion of lungs determined by volume and elasticity. It can be affected by: decreased/ increased compliance
Airway resistance=
explains the bronchial diameter.
- The brochoconstriction/ dilation can determine resistance.
Alveolar surface tension=
arises from attractive forces between molecules. A high surface tension would:
- cause alveoli to collapse
- Severly decrease compliance
- Production of surfactant help break down surface tension
Henrys law=
The amount of oxygen that dissolves into the bloodstream is directly proportional to the partial pressure of oxygen in alveolar air
- So if there is high partial pressure in alveolus, O2 dissolves into blood.
- If there is low partial pressure in alveolus, CO2 dissolves out of blood.
What are some upper/ lower respiratory tract infections?
Upper: Common cold, sinusitis, tonsillitis, laryngitis
Lower: Bronchitis, bronchiolitis, chest infections, pneumonia
What is the structure & function of the nose?
- Air enters nares (nostrils) into the nasal cavity
- Nasal cavity is connected to several paranasal sinus cavities in cranial bones
- These cavities are lined with high vascular mucosal membrane (mucosa) Mae of ciliated columnar epithelial cells
- Network of veins warm the air
- Glands produce mucus, this moistens air and traps debris and bacteria. Mucus contains lysozyme
- Cilia move the mucus towards back of throat (pharynx) to be swallowed
Smell: olfactory receptors are stimulated by chemicals in air, and your brain interprets these as smells.
Pharynx=
- Passage for food and fluids, as well as air
- Warms and humidifies air (same as. nasal cavity)
- Hearing: protects middle ear from pressure changes
- Protection: dense with lymphoid tissue including tonsils
- Speech: resonance (sound) created in pharynx
Larynx/ voice box=
- Larynx allows us to make sounds. it wars and humidifies air.
- It has thyroid cartilage or Adam’s apple. The cartilage forms a framework with vocal cords.
- The Broca’s area is associated with larynx, it is located in left hemisphere of brain that controls vibrations in the vocal cords.
Where is the conducting zone?
Conducting zone is the passage of air.
It is in the upper respiratory tract
Gas exchange
- Occurs between alveoli and capillaries and between capillaries and tissues
- Gases move by diffusion across membranes
- Diffusion is based on concentration of molecules- from high concentration to low concentration seeking equilibrium
Daltons law= in a mix of non-reacting gases, the total pressure is the sum of the partial pressures of each gas in the mix. This helps explain gaseous exchange
Gas exchange in alveoli / lungs
- Deoxygenated blood arrives from the pulmonary artery through the capillary with a PO2 (partial pressure of oxygen) of 5.3kPa PCO2 (partial pressure of CO2) of 5.8kPa.
- As it comes into contact with alveoli, gases diffuse down the gradient , so O2 continues to move into the capillary but CO2 moves out of capillary into the alveoli
Gas exchange in tissues
- Oxygenated blood arrives in the tissue
- Wall of capillary is very thin (1cm wide) so oxygen moves out of the capillary into the tissue from high concentration to low concentration, down the gradient from 13.3kPa into 5.3kPa.
- C0z then moves into the blood from high concentration in tissues to low concentration in blood.
