Respiratory system Flashcards
What are the two main functions of the system?
Pulmonary ventilation (inspiration and expiration) Gaseous exchange.
Describe gas transport?
Oxygen is transported by the blood either:
Combined with haemoglobin (Hb) in the red blood cells (>97%) OR
Dissolved in the blood plasma (<3%
What is Haemoglobin?
Haemoglobin molecules can transport up to four O2’s
When 4 O2’s are bound to haemoglobin, it is 100% saturated, with fewer O2’s it is partially saturated.
How much oxygen can combine with haemoglobin?
This depends on the PARTIAL PRESSURE of oxygen (PO2
IF PO2 is High = Haemoglobin will readily combine with oxygen to form oxyhaemoglobin.
Where in the body is the PO2 Low ?
Partial pressure is low at the muscle sites. When the haemoglobin releases the oxygen it is said to dissociate with oxygen.
What is Myoglobin?
In the muscle, oxygen is stored by myoglobin.
This has a high affinity for oxygen and stores the oxygen until it can be transported from the capillaries to the mitochondria.
where does aerobic respiration takes place.
The mitochondria
Factors affecting Haemoglobin Saturation?
3
Decrease in blood acidity (pH)
Increase in blood temperature
Increase in partial pressure of Carbon Dioxide concentration
Bohr Shift?
This is caused by the increase in carbon dioxide in the blood, which results in an increase in the concentration of hydrogen ions in the blood lowering
the pH.
The volume of air inspired or expired per minute is the minute ventilation and can be calculated with the equation?
Breathing rate (f) x Tidal volume (TV) = Minute Ventilation (VE)
What is tidal volume?
The volume of air inspired or expired per breath
Average at rest – 0.5 litres
Change during exercise – (increase)
What is Inspiratory Reserve Volume?
The volume able to be forcibly inspired during normal breathing
Average at rest – 3.0 litres
Change during exercise (decrease)
What is Expiratory Reserve Volume?
The volume able to forcibly expired, after a normal breathe
Average at rest – 1.3 litres
Change during exercise – Small decrease
What is Residual Volume?
The volume of air that remains in the lungs after forced maximum expiration
Average at rest – 1.2 litres
No change
What is Minute Ventilation?
Ventilation is the amount of air breathed in one minute.
Average at rest – 6.0 litres
Changes during exercise = BIG increase
Minute ventilation (VE) = Tidal Volume (TV) X Breathing Rate (f)
The mechanics of breathing
Describe When breathing in (inspiration)
Intercostal muscles contract
lift ribs upwards and chest to expand
diaphragm contracts
pulls down and flatterns
lungs increase in size and chest expands
pressure inside lungs falls as they expand
the high pressure of air outside means air is now inside lungs through nose and mouth
The mechanics of breathing
Describe when breathing out (expiration)
Intercostal muscles relax ribs move downwards and inwards chest gets smaller diagram relaxes lungs decrease in size chest gets smaller squeeze ribs and diaphragm pressure inside lungs increases pressure outside is now lower so air is forced oit of the lungs
How is CO2 removed?
Combines with water
Combines with hemoglobin
Dissolved in blood plasma
How does your breathing rate change during sub maximal exercise?
Anticipatory rise in VE due to adrenaline (1)
Rapid increase in VE at the start due to increased breathing rate and tidal volume in increase oxygen delivery. (2)
VE plateau’s as oxygen supply meets demand (3)
Initial rapid decrease in VE before more gradual decrease occurs until returning to resting. (4)
How does your breathing rate change during maximal exercise?
During maximal exercise, VE does not plateau.
Due to the exercise being maximal, there is a constant growing demand for oxygen which the VE must continually thrive to meet.
Tidal volume will plateau, however the further increase is met through increased breathing rate.
Where are the lungs?
Thoracic cavity
What is the Thoracic cavity?
The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle)
Expiration at rest is?
Passive
What is the Alveoli?
Increase the efficiency of gas exchange by:
Forming a vast surface area for gaseous exchange
Having a single cell layer of epithelial cells reducing the distance for gaseous exchange
What is the RCC?
The RCC is sent information from the sensory nerves when exercise or recovery begins.
The RCC sends instructions through motor nerves to change the rate of respiratory muscle contraction – What muscles are used in respiration?
What are the 2 centres within the RCC?
Inspiratory centre (IC) Expiratory Centre (EC)
What does the inspiratory centre do?
Stimulates the inspiratory muscles to contract
What does the Expiratory center do?
Inactive at rest
Stimulates expiratory muscles to contract during exercise
At rest, what is responsible for breathing rate?
Inspiratory Center
How does the inspiratory center work at rest?
Nerve impulses are sent to stimulate the inspiratory muscles to contract.
Intercostal nerve = external intercostals
Phrenic nerve = diaphragm
Approximately 500ml of air will be inspired at rest.
Expiration is passive as the lung tissues will naturally recoil and the diaphragm/external intercostals will relax.
Therefore the expiratory centre is inactive at rest.
RCC - Receptors react to 2 types of stimuli, what are they?
What are they detected by?
Chemical changes
Neural changes
Chemical changes are detected by Chemoreceptors
Neural stimuli are detected by Thermoreceptors, Proprioceptors and Baroreceptors
What do each detect:
Chemoreceptors ?
Thermoreceptors ?
Proprioceptors ?
Baroreceptors ?
– blood acidity, CO2 concentration, O2
– blood temperature
– activity in the muscles and joints
– lung inflation
What do Chemoreceptors, Thermoreceptors, Proprioceptors do during exercise?
Inform the IC, increases diaphragm and external intercostal stimulation,
Can cause the IC to also recruit sternocleidomastoid and pectoralis minor muscles when necessary.
What do Baroreceptors do during exercise?
Inform the EC on the extent of lung inflation (pressure).
If lung tissue is excessively stretched, EC recruits internal intercostals and rectus abdominis to reduce thoracic cavity volume and increase air pressure. This pushes the air our more forcefully.
What is gaseous exchange?
How does it work?
Gaseous exchange is the movement of gases across a membrane.
This movement occurs through the act of diffusion.
Gases will diffuse from an area of high partial pressure to low partial pressure.
The partial pressure of oxygen is pO2.
The partial pressure of carbon dioxide is pCO2
Where are the two sites gaseous exchange can occur?
External site – Between the alveoli and blood capillary membrane
Internal site – Between the blood capillary and muscle cell membrane.
How does gaseous exchange diffuse?
Gases will diffuse from areas of high partial pressure to low partial pressure.
The difference between high to low pressure is called Diffusion Gradient.
The steeper the diffusion gradient, the quicker gaseous exchange occurs.
Gaseous exchange external respiration -
8 things
Exchanging of gases at the lungs
Oxygen => Alveoli to capillaries
Carbon Dioxide => Capillaries to alveoli
Oxygen and haemoglobin combine – Oxyhaemoglobin
CO2 diffuses rapidly
Blood leaving lungs is saturated with O2
Low pressure of pO2 in blood, high pressure in alveoli
High pressure of pCO2 in blood, low pressure in alveoli
Gaseous exchange internal respiration
8 things
Exchanging of gases at the muscle cells
Oxygen => Capillaries to muscle cells
Carbon Dioxide => Muscle cells to Capillaries
Oxygen and the haemoglobin detach
Blood leaving muscles is saturated with CO2
High pressure of pO2 in blood, low pressure in muscle
Low pressure of pCO2 in blood, high pressure in muscle
What 2 things change gaseous exchange when doing exercise?
Exercise increases demand for Oxygen and produces more Carbon Dioxide.
Minute ventilation and cardiac output rises to meet these increases.
Oxygen during external respiration?
The O2 diffusion gradient steepens
Greater amounts of O2 diffuse from the alveoli to the blood. (High pO2 in alveoli, low pO2 in blood)
Carbon dioxide during external respiration?
The CO2 diffusion gradient steepens.
Greater amount of CO2 diffuses from blood to the alveoli (High pCO2 in the blood, low pCO2 in the alveoli)
Oxygen during internal respiration?
The O2 diffusion gradient steepens.
Greater amount of O2 diffuses from the capillary blood to the muscle cell. (High pO2 in blood, low pO2 in muscle)
Carbon dioxide during internal respiration?
The CO2 diffusion gradient steepens.
Greater amount of CO2 diffuses from the muscle cell to the capillary blood (High pCO2 in the muscle cell, low pCO2 in the capillary blood)
When pO2 is high ?
When pO2 is low?
more oxygen associates to form oxyhaemoglobin.
the oxygen more readily dissociates (detaches).
Explain THE BOHR SHIFT – DURING EXERCISE?
Increases in temperature
Increases on CO2 production (raising p CO2)
Decreases in PH (increases in lactic acid and carbonic acid)
These changes all move the oxyhaemoglobin curve to the right.
This is known as the Bohr shift or Bohr effect.
Explain THE BOHR SHIFT – THE RECOVERY?
The oxyhaemoglobin dissociation curve shifts back to the left.
haemoglobin saturation with oxygen returns to its original levels.
Increasing association of oxygen at the alveoli.
Helping to oxygenate blood stream and remove waste products.
