Respiratory System Flashcards
Function of the respiratory system
Delivering oxygen to cells whist ridding CO2 from body
pH balance
Controlling body temperature
Shaping air flow for speech
Conducting
Conducting: Moves air into and out of the lungs
No gas exchange
Filter, warm and humidify air
Respiratory: Moves the respiratory gases in and out of the blood
Site of gas exchange
Nasal and Oral cavity
-bring in air to be filtered, warmed, moistened
-cilia protect nasal passageways and filter out dust and other particles
Pharynx
Location of 2 airway passages meeting
-caries both food and air
-digestion and respiration
-leads to oesophagus and trachea (via larynx)
Larynx
- voice box, where vocal cords are located
-lined with cilia
-leads to trachea
Trachea
-wind pipe
-cartilage ring
-lined with cilia to sweep tiny particles out of airways preventing them from entering the lungs.
Primary Bronchus
-left and right bronchus; enables fresh air to reach alveoli
-each enters the respective side of the lung
-divides into smaller branches called bronchioles
-bronchioles end in alveoli surrounded by capillaries where oxygen and carbon dioxide exchange occurs
Diaphragm
-helps to create a pressure enabling air to enter and exit the respiratory system
Conducting Zone
nasal passages, pharynx, larynx, trachea, bronchus
moves air into and out of the lungs
Respiratory Zones
Consists of Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli)
~300 million alveoli account for most of the lung’s volume
Main site for gas exchange - Moves respiratory gases in and out of the blood
Cup shaped pouch
Upper respiratory system components
nose, mouth and pharynx
Lower respiratory system
larynx, trachea, bronchus, bronchioles, alveoli
Respiratory membrane
for the seamless transition of O2 and CO2 particles across it’s surface.
It is LARGE because the increase in surface area allows for an increase in gas exchange to occur. It is SMOOTH and THIN for more efficient exchange of gasses as gas can transport through relatively short distances.
Functions of cells in the respiratory system
Type 1 Alveolar cells (Thin/broad squamous)
Type 2 Alveolar cells (Round/cuboidal/ grape like)
Alveolar macrophages
Type 1 Alveolar cells
-thin walls of these cells allow for rapid gas diffusion between the air and blood
-95% if surface area of alveoli
Type 2 Alveolar cells (Round/cuboidal/ grape like)
-repair alveolar epithelium when squamous type 1 cells are damaged
-secrete pulmonary surfactant (phospholipids + proteins), coats alveoli, prevents pressure buildups from collapsing alveoli when exhaling
-5% of surface area of alveoli but outnumber type 1
Alveolar macrophages
-drift between alveolar lumen cleaning debris through phagocytosis
-most numerous type of cell in the lungs
Boyles law
The pressure of a gas in a closed container is INVERSELY PROPORTIONAL to the volume of that container
P1V1 = P2V2
We can change the flow of air in and out of our lungs by changing the volume.
Change in lung volume Change in Lung P Flow of gasses
Because the volume of alveoli is so small, the pressure will be very high.
Inspiration
Diaphragm contracts
intercostal muscles contract (pull upwards)
lungs stretched (increase volume)
Decrease pressure
Air flow into lungs
Inspiration
Diaphragm contracts
intercostal muscles contract (pull upwards)
lungs stretched (increase volume)
Decrease pressure
Air flow into lungs
Expiration
Diaphragm relaxes(passive)
intercostal muscles relax
lungs recoil (decrease volume)
increase pressure
air flow out the lungs
spirometry Test
measure the airflow in and out of lungs over time
FVC meaning
Forced Vital Capacity
The maximum amount of air which can be exhaled after a maximum inhalation.
Forced Expiratory Volume in 1 second (FEV1)
The amount of air which can be forcefully exhaled in 1 second. Normal about 75% of FVC
Minute Ventilation (MV)
the total amount of gas flow into or out of respiratory trat one
Alveolar Ventilation Rate
Flow of gasses into and out of the alveoli in 1 minute
Anatomical dead space
the volume of the conducting zone conduits (~150mL)
Alveolar Ventilation
Inspiring larger volumes = AVR increases
Rapid shallow inspirations = AVR decreases (Most of the air never reaches the respiratory zone for gas exchange to occur)
*Therefore, AVR is more accurate than MV because it takes into account the anatomical dead space in alveoli.
Variations to these Values…
- Obstructive Pulmonary disease
a. Increased airway resistance
b. Eg. Bronchitis, Emphysema, COPD, asthma
c. TLC, FRC, RV may increase - Restrictive Pulmonary disease
a. Reduced TLC due to disease of fibrosis
b. Eg. Pulmonary fibrosis
c. TLC, VC, FRC, RC declines
Gas Exchange in the blood, lungs and tissues:
Partial pressure: Measure of concentration of a gas in a mixture of gasses, mmHg. Pressure that a certain gas exerts in a certain gas mixture caused by the impact of moving molecules against each other and any surrounding surfaces.
Partial pressure drives the movement of gases by forcing gas molecules to dissolve through the alveolar membrane and then to pulmonary capillaries. PP of each gas already in solution in the blood meaning some gas molecules escape back into the alveoli. Diffusion in both directions between 2 PP’s determines the net direction of diffusion.
Neural control of ventilation
Breathing depends on repetitive stimuli from the brain
- Neurons in the medulla oblongata and the pons control unconscious breathing
2 groups of neurons in the Medulla:
Groups of neurons Regulate
Ventral respiratory center -when breathing demands increase only
-forceful inhalation and exhalation
Dorsal respiratory center -always functioning during breathing
-regulates the RATE and RHYTHM
-sensitive to blood pH, CO2 and O2 levels
Function of neurons located in Pons:
-pontine respiratory centers
-receive info from higher brain centers in cerebral cortex, limbic system and hypothalamus
-send info to medulla respiratory centers to adjust depth and length of breathing
- Voluntary control provided by the motor cortex
-inspiratory neurons: fire during inspiration
Impulses travel via phrenic nerve excite the diaphragm and intercostal nerves excite intercostal muscles
-expiratory neurons: fire during forced expiration
Main factors that control ventilation
1.chemoreceptors
2. central (PCO2, H+)
3.Peripheral chemoreceptors (PO2, PCO2, H+)
They detect chemical changes (CO2, O2, pH) in the blood
Respond to changes in CO2 by converting it to H+
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Hb- oxygen binding protein
Each Hb molecule contain 4 globular proteins, each having an iron-containing heme molecule (red pigment)
Heme molecule: bonds to oxygen RAPIDLY AND REVERSIBLY!!!
Hemoglobin can bind to 4 oxygen molecules
O2 and Haemoglobin
Loading and unloading of oxygen is facilitated by change in shape of Hb.
- As O2 binds, Hb affinity for O2 increases
- As O2 is released, Hb affinity for O2 decreases
- This means if Hb binds one O2, it is even easier to bind a 2nd, 3rd, and 4th O2 and vice versa
If all 4 heme groups carry O2 molecules, it is said to be Fully 100% saturated
If 1-3 heme groups carry O2 molecules, it is said to be Partially saturated
Factors that influence Hb saturation
A) Influence of PO2 on Hb saturation
Oxygen-haemoglobin dissociation curve :
-shows how binding and release of O2 is influenced by the PO2
-Hb saturation plotted against PO2 is not linear
-S shaped curve
-gradient is steep between 10-50mmHg
-gradient is flatter between 70-100 mmHg
Hb is almost completely saturated at a PO2 of 70mmHg
Further increases in PO2 produce only small increases in O2 binding, therefore…
O2 loading and delivery to tissues can still be adequate when PO2 is below normal levels!
At rest, only 20-25% of bound O2 is unloaded during one systemic circulation – blood leaving tissues stil has 75% Hb saturation
If O2 levels in tissues drop (Eg. Due to exercise): More O2 rapidly dissociates from Hb and is used by cells (steep part of the curve) without any increase in respiratory rate or cardiac output needed
other factors that effect Hb saturation
B) Increases in Temperature, H+, PCO2 and BPG:
-modify the structure of Hb and decrease it’s affinity for O2 = enhancing O2 unloading
-increases occur in systemic capillaries where O2 unloading is the goal
-shift the O2-Hb dissociation curve to the right
- acidic pH weakens the haemoglobin-O2 bond … increasing O2 offloading (shifts curve to the right)
D) Heat production increases
- directly and indirectly decreasing Hb affinity for O2 … increasing O2 offloading (shifts curve to the right)
CO2 transport
CO2 is transported in the blood in 3 forms:
1. 7-10% dissolved in plasma
2. 20% bound to globin in Hb
a. Carbaminohaemoglobin (when bound to Hb)
b. Does not compete with O2 transport due to different binding site
3. 70% transported as bicarbonate ions (HCO3-) in plasma
Transport as Bicarbonate ions
CO2 combines with water to form carbonic acid (H2CO3) which quickly dissociates… to H+ ions and Bicarbonate ion