3. The Respiratory System Flashcards
What happens to oxygen in the vascular system?
- During exercise O2 diffuses into the capillaries supplying the muscles
- 3% dissolves in plasma
-97% combines with haemoglobin to form oxyhemoglobin
-At tissues,O2 dissociates from haemoglobin due to low pressure of O2 at tissues - within muscle, O2 stored by myoglobin
→ myoglobin has a high affinity (liking) for O2
→ it stores O2 until it can travel through capillaries to mitochondria (stored in muscles - where aerobic respiration takes place)
Myoglobin definition
Protein in muscle that stores oxygen
Carbon dioxide in vascular system
- 70% transported in blood as hydrogen carbonate (bicarbonate) ions
- produced by muscles as a waste product, diffuses into bloodstream
- taken up by red blood cells (combines with H2O ) and forms carbonic acid
→ most dissociates to bicarbonate & hydrogen ions - 23% combines with haemoglobin
-7% dissolves in plasma
What is respiration?
- body needs continuous supply of O2 to produce energy (ATP)
- when we use O2 to break down food to release energy or when we exercise, CO2 is produced & must be removed
Respiration definition
The taking in of O2 & removal of CO2
Respiratory system function
To transport oxygen from the air we breathe through a system of tubes into our lungs and then into the bloodstream
Structure of the lungs
-Lungs found in thorax
- protected by rib cage & separated from abdomen by diaphragm muscle
- each lung is surrounded by pleura, a double membrane which contains lubricating pleural fluid
- right lung is slightly larger than left
- right lung has 3 lobes, left has 2
Haemoglobin characteristics
-In red blood cells
- transport oxygen from lungs to tissue
- binds with oxygen to form oxyhaemoglobin
Myoglobin characteristics
-In muscle cells
- stores & releases oxygen in muscles
- high affinity for oxygen so can hold & release when levers are low
How does an oxygen molecule travel through the bloodstream?
- Air drawn through nose & mouth
- Passes through pharynx into larynx
- Epiglottis covers opening of larynx to prevent food entering lungs
- Air moves into trachea (windpipe)
- Air passes into 1 of 2 brooch - 1 enters each lung
- Air travels into bronchioles
- at the end of the bronchioles, air enters 1 of many millions of alveoli
- Gaseous exchange occurs in alveoli - takes place by diffusion
What happens when you inhale?
- External intercostal muscles contract
- diaphragm contracts (flattens)
- pulls ribcage up & out
- causes thoracic cavity size to increase
- decreased pressure in thoracic cavity
- gases move from areas of high → low pressure
-Oxygen moves from atmosphere to lungs
Exercise:
- sternocleidomaftoid muscle lifts the sternum & pectoralis minor raises s the ribs, scalene muscles (neck)
What happens when you exhale?
- external intercostal muscles relax
-Diaphragm relaxes (domes) - pulls ribcage down & in
- thoracic cavity decreases size
- thoracic cavity increases pressure
-gases move from lungs into atmosphere
Exercise:
- internal intercostals help pull ribs down
- abdominals push diaphragm up
Alveoli role
Responsible for gas exchange between lungs & blood
Alveoli structure
- dense capillary networks - supply of oxygen
- extremely thin (one cell thick) - create large surface area & small diffusion distance for greater oxygen uptake
Mechanics of breathing
- Air moves from area of high→ low pressure
- greater pressure difference = faster the air flows
- during inspiration pressure needs to be lower in lungs than atmosphere
- during expiration the pressure needs to be higher in lungs than atmosphere
Tidal volume - definition & values
Volume of air breathed in or out per breath
- rest = 0.5L
-Exercise = ↑
Inspiratory reserve volume - definition & values
Volume that can be forcibly inspired after a normal breath
-Rest = 3.1L
-Exercise =↓
Expiratory reservevolume - definition & values
Volume that can be forcibly expired after a normal breath
- rest = 1.2 L
-Exercise = slight ↓
Residual volume - definition & values
Volume that remains in the lungs after maximum expiration
-Rest =1.2L
-Exercise= no change
Vital capacity - definition & values
Volume forcibly expired after maximum inspiration in one breath
TV + IRV + ERV = VC
- rest = 4.8 L
-Exercise = slight ↓
Minute ventilation - definition & values
Volume breathed in or out per minute
-Rest =6L
-Exercise = large ↑
Total lung capacity - definition & values
Vital capacity + residual volume
-Rest =6L
-Exercise = slight ↓
How does exercise affect lung volumes?
Move oxygen is required so breathing rate & tidal volume need to increase, this reduces the ability to breathe in or out an extra amount of air so IRV & ERV decrease
Minute ventilation - definition & values
Volume of air inspired or expired per minute
Number of breaths per min (~12) x tidal volume (~0.5L) = 6L/min
What is a spirometer trace?
Graphical represensation produced by a spirometer - a device that measures lung function
- records volume of air inhaled/exhaled over time
O2 demand & CO2 production - maximal vs submaximal
-Max: more O2 needed, more CO2 produced, ventilation increases
-Submax: lower O2 demand, less CO2 output, ventilation rises to steady state
Ventilatory response - maximal vs submaximal
-Max: ventilation spikes to expel high CO2 levels from lactic acid accumulation
-Submax: ventilation reaches steady state as aerobic metabolism meets O2demand without excess lactic acid
Anaerobic vs aerobic metabolism - maximal vs submaximal
-Max: shifts partly to anaerobic, generating lactic acid & increasing ventilation
-Submax: remains largely aerobic, keeping ventilation lower & stable
Respiratory Control Centre (control of ventilation)
Nervous system can increase or decrease the rate, depth (TV) and rhythm of breathing
- breathing rate regulated by respiratory muscles (controlled involuntarily)
- split into inspiratory centre & expiratory cente
Inspiratory centre stimulated by…
-Baroreceptors: ↑ blood pressure
-Chemoreceptors: ↑ blood acidity (↓ ph),↑ CO2,↓O2
-Proprioreceptors: ↑ muscle movement
→ length: muscle spindles
→ tension: Golgi tendon organs
Expiratory centre stimulated by…
Stretch receptors: prevent overinflation of lungs
→ if excessively stretched they send impulses to expiratory centre to induce expiration (Heuring Breuer reflex)
Inspiratory centre nerve
Phrenic nerve
Phrenic nerve causes…
- Diaphragm contracts
- External intercostals contract
(sternocleidomastoid, pectoralis minor, scalene)
Result of phrenic nerve actions
Increased inspiration→ increased breathing rate & depth (TV)
Expiratory centre nerve
Intercostal nerve
Intercostal nerve causes…
- Diaphragm relaxes
-external intercostals relax
(Abdominals, internal intercostal)
Result of intercostal nerve action
Increased expiration → increased breathing rate & depth (TV)
Diffusion definition
Movement of gas molecules from an area of high concentration / partial pressure to an area of low concentration / partial pressure until equilibrium is reached
Gas exchange definition
Movement of O2 from air into blood & CO2 from blood into air
Where does external respiration take place?
Between lungs & capillaries
Where does internal respiration take place?
Between capillaries & tissue
-O2 enters tissue, CO2 enters capillaries
-Part of systemic circulation
What does the oxyhemoglobin dissociation curve show?
How much oxygen separates from the haemoglobin it is bound to
What is haemoglobin & oxygen saturation?
Haemoglobin is a protein that can carry up to 4 oxygen molecules each
Oxygen saturation reflects how much oxygen is being carried by the blood
Usually measured as a %
What is the oxygen saturation in the lungs?
- when blood passes through the capillaries surrounding the lungs, oxygen binds to haemoglobin resulting in high saturation levels
- this oxygen rich blood circulates to deliver oxygen to tissues & organs
What is the oxygen saturation in the tissues ?
- as blood reaches the tissues, some O2 is released (dissociates) from haemoglobin to meet cellular demands
- reduces oxygen saturation in blood as haemoglobin releases O2
What is the oxygen saturation during exercise?
When more O2 is needed, haemoglobin releases more O2 leading to lower saturation so it moves back to the lungs for resaturation
Causes of oxygen dissociation from haemoglobin are…
- Increase in blood & muscle temp
- decrease in partial pressure of 02 in muscle (↑ diffusion gradient)
- increase in partial pressure of CO2 (↑ gradient)
- increase in acidity caused by more CO2 / H+ / lactic acid in blood (Bohr effect)
Partial pressure definition
The pressure exerted by a single type of gas within a mixture of gases
- represents the contribution of each gas to the total pressure
Partial pressure of gases in lungs
O2 has ↑p.p in alveoli man blood
CO2 has↑ p.p in blood than alvedi
Partial pressure of gases in tissues
O2 has ↑ p.p in blood than tissues
CO2 has ↑ p.p in tissues than blood
AVO2 diff definition
The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles
What is the AVO2 diff at rest ?
Low difference of O2 between arterial & venous blood ( 8x O2 enters, 2x used, 6x leaves)
During rest there is a low oxygen demand in the muscles
What is the AVO2 diff during exercise?
High difference of O2 between arterial & venous blood (8x O2 enters, 6x used, 2x leaves)
During exercise there is a higher demand for O2 in the muscles. More O2 dissociates from haemoglobin as there is a higher production of CO2 in the muscle.
How can a performer increase their AVO2 diff? (Physiological adaptations)
- Increase muscle capillary density: larger surface area for oxygen exchange
- Enhance mitochondrial density:↑ size, number & efficiency, use O2 to produce ATP
- Improve haemoglobin levels: ↑ haemoglobin for O2 to bind to
- Improve myoglobin levels: improve ability to store & transport O2
VO2 max definition
Maximum rate someone can consume O2 during intense exercise ( ml/kg /min)
→ cardiac output (q) x AVO2 diff = VO2 max
