Respiratory system - all

what is the word to help remember what causes the Bohr shift?

MCCOAT

what does MCCOAT stand for?

• M - muscle activity increases

• C - curve moves to the right

• C - carbon dioxide increases

• O - oxygen decreases

• A -  more acidity (increase in lactic acid - low pH)

• T - increase temperature

why does an increase in muscle activity cause the oxygen dissociation curve to shift to the right?

So more dissociation happens so the muscles get more oxygen.

why is a warm up important in terms of partial pressure?

• A warm up is important as partial pressure of oxygen will decrease so more oxygen will disassociate, when temperature rises 37 to 39 degrees C.

what happens in relation to the Bohr shift during recovery and why?

• During recovery the oxyhaemoglobin curve shifts back to the left.

• This returns haemoglobin saturation with oxygen to it's original relationship.

• This allows a greater uptake or association of oxygen to haemoglobin at the alveoli - oxygenating the blood stream to flush waste.

how many molecules of oxygen can haemoglobin carry?

4

what depends on the partial pressure of oxygen (pO2)? (in terms of haemoglobin)

the amount that associates

What happen when the partial pressure is high? (in terms of haemoglobin)?

• oxygen readily associates

• therefore blood leading to the alveoli is 98% saturated with oxygen

• this relationship is shown in the oxyhaemoglobin dissociation curve

what is the oxyhaemoglobin dissociation curve?

• a curve which shows how haemoglobin saturation varies as partial pressure of oxygen changes.

• E.g. during exercise pO2 in the muscles drops to 5 and the saturation of haemoglobin drops to 25%. 75% of oxygen is released to the muscle cells in order to supply the increased demand of oxygen required for respiration.

where is the RCC located?

In the medulla oblongata

what 2 centres is the RCC made up of?

• the inspiration centre

• the expiration centre

what happens in the inspiration centre?

• Has intercostal nerve and phrenic nerve which work together to control diaphragm and intercostals.  

• Works at both rest and exercise. 

what happens in the expiration control centre?

Only kicks in during exercise. 

what does the RCC do during exercise?

• uses the receptors to detect change:

• Chemoreceptors: detect ↑CO₂, ↑H⁺, ↓O₂

• Thermoreceptors: detect ↑blood temperature

• Proprioceptors: detect ↑muscle and joint movement

• These receptors stimulate the inspiratory centre (IC)

• IC increases force of diaphragm & external intercostals

• IC recruits sternocleidomastoid & pectoralis minor → ↑depth of inspiration

• Baroreceptors: monitor lung inflation

• Excessive stretch stimulates expiratory centre (EC)

• EC recruits internal intercostals & abdominals → forced expiration

• Combined IC & EC activity → ↑breathing rate and depth

what are the 4 receptors which help regulate the respiratory system during exercise and what do they measure?

• baroreceptors: located in lung tissue and bronchioles and inform the state of lung inflation. 

• proprioceptors: inform of motor activity in the muscles and joints. 

• thermoreceptors: inform of an increased blood temperature. 

• chemoreceptors: located in aorta and carotid arteries and pick up an increase in blood acidity, increases in CO2 conc and decrease in O2 conc. 

what does the RCC do during rest?

• IC is responsible for the rhythmic cycle of breathing.  

• Nerve impulses are generated and stimulate the inspiratory muscles causing them to contract via the: intercostal nerve to the external intercostals and the phrenic nerve to the diaphragm.  

• This causes thoracic activity volume to be increased.  

• Approx. 500ml of air will be inspired. 

• After approx. 2 seconds, stimulation stops and the inspiratory muscles relax. 

• Lung tissues recoil, causing passive expiration. 

• This will be repeated approx. 12-15 times per minute. 

• The expiratory centre is inactive during rest due to the natural relaxation of the diaphragm and external intercostals.  

when is the phrenic nerve stimulated and what does it cause?

• Stimulated by the inspiratory centre (IC) within the respiratory control centre when chemoreceptors detect ↑CO₂, ↑H⁺ and/or ↓O₂ (at exercise)

• Sends motor impulses to the diaphragm

• Diaphragm contracts and flattens

• Thoracic cavity volume increases

• Lung pressure decreases

• Air is drawn into the lungs, initiating and increasing inspiration

when is the intercostal nerve stimulated and what does it cause?

• Stimulated by the inspiratory centre (IC) within the respiratory control centre when chemoreceptors detect ↑CO₂, ↑H⁺ and/or ↓O₂ (at exercise)

• Sends motor impulses via the intercostal nerve to the external intercostal muscles

• External intercostals contract

• Rib cage moves up and out

• Thoracic cavity volume increases

• Lung pressure decreases

• Air is drawn into the lungs, increasing inspiration

define association (in terms of haemoglobin)

the combining of oxygen with haemoglobin to form oxyhaemoglobin. 

define dissociation (in terms of haemoglobin)

the release of oxygen from haemoglobin. 

define oxyhaemoglobin (in terms of haemoglobin)

a bright red substance formed by the combination of haemoglobin with oxygen, present in oxygenated blood. 

define haemoglobin

a red protein responsible for transporting oxygen in the blood of vertebrates. Its molecule comprises four subunits, each containing an iron atom bound to a haem group. 

define saturation (in terms of haemoglobin)

the extent to which haemoglobin in the blood is bound with oxygen 

define external respiration

the process of exchanging gases between the alveoli in the lungs and the blood 

define internal respiration

the exchange of gases, between the body's tissue cells and the blood 

define partial pressure

the pressure exerted by an individual gas held in a mixture of gas.  

define diffusion

the movement of gases across a membrane down a gradient from an area of high pressure (or conc) to an area of low pressure (or conc) 

define diffusion gradient

the difference in areas of pressure (or conc) from one side of a membrane to the other.  

define pulmonary ventilation

the inspiration and expiration of air from the atmosphere behind us.

define gaseous exchange

the extraction of oxygen from the air into the blood stream and then into the muscle tissues

define breathing frequency

the number of breaths taken per minute.

what percent of blood is plasma and what percent is blood cells?

blood consists of:

• 55% plasma

• 45% blood cells

what percent of blood combines with haemoglobin to produce oxyhaemoglobin and what happens to the rest?

• 97% combines with haemoglobin to produce oxyhaemoglobin (HbO2)

• the other 3% is dissolved within the blood plasma

how is carbon dioxide transported in the blood?

• 70% dissolved in water and carried as carbonic acid

• 23% combines with haemoglobin to create carbaminohaemoglobin

• 7% dissolved in blood plasma

define tidal volume

Tidal volume is the volume of air inhaled or exhaled in one normal breath.

define minute ventilation

Minute ventilation is the total volume of air inhaled or exhaled per minute.

resting and maximal value for breathing frequency

• resting = 12 - 16

• maximal = 40 +

what are the resting and maximal for tidal volume

• resting = 0.5 litres

• maximal = 3-5 litres

resting and maximal for minute ventilation

• resting = 6-8 litres

• maximal = 200+ litres

how does external respiration work at rest?

• Occurs in the alveoli of the lungs

• O₂ diffuses from alveoli → capillary blood

  • High O₂ in alveoli, low O₂ in blood

• CO₂ diffuses from capillary blood → alveoli

  • High CO₂ in blood, low CO₂ in alveoli

• Diffusion gradients are moderate

• Meets low oxygen demand at rest

how does external respiration work during exercise?

• Breathing rate and depth increase

• O₂ diffuses from alveoli → blood at a faster rate

  • Steeper gradient due to ↓blood O₂

• CO₂ diffuses from blood → alveoli at a faster rate

  • Steeper gradient due to ↑blood CO₂

• Ensures sufficient oxygen supply to working muscles

how does internal respiration work during rest?

• Occurs at muscle capillaries

• O₂ diffuses from blood → muscle cells

  • High O₂ in blood, low O₂ in muscles

• CO₂ diffuses from muscle cells → blood

  • High CO₂ in muscles, low CO₂ in blood

• Diffusion gradients are small

• Matches low metabolic demand

how does internal respiration work during exercise?

• Muscles increase aerobic respiration

• O₂ diffuses rapidly from blood → muscles

  • Very steep gradient due to ↓muscle O₂

• CO₂ diffuses rapidly from muscles → blood

  • Very steep gradient due to ↑muscle CO₂

• Increased temperature and CO₂ maintain steep gradients

• Supports increased energy production

what are the partial pressures at external respiration at rest?

• PO2 in alveoli = 100

• PO2 in blood capillaries = 40

• so diffusion of O2 goes from alveoli to blood capillaries

• PCO2 in alveoli = 40

• PCO2 in blood capillaries = 45

• so diffusion of CO2 goes from blood capillaries to alveoli

what are the partial pressures at internal respiration at rest?

• PO2 in muscle cell = 40

• PO2 in blood capillaries = 100

• so diffusion of O2 goes from blood capillaries to muscle cell

• PCO2 in muscle cell = 45

• PCO2 in blood capillaries = 40

• so diffusion of CO2 goes from muscle cell to blood capillaries

what are the partial pressures at internal respiration during exercise?

• PO2 in muscle cell = 5

• PO2 in blood capillaries = 100

• so diffusion of O2 goes from blood capillaries to muscle cell

• PCO2 in muscle cell = 80

• PCO2 in blood capillaries = 40

• so diffusion of CO2 goes from muscle cell to blood capillaries

Describe how oxygen and carbon dioxide are exchanged between the lungs, blood, and body tissues at rest (including exact values).

 

 

 

At rest:

 

• Blood arriving at the lungs has low O₂ (40) and high CO₂ (45).

• In the alveoli, air has high O₂ (105) and low CO₂ (40).

• Because of these differences, O₂ diffuses into the blood and CO₂ diffuses out (external respiration).

• Blood leaving the lungs (pulmonary veins → left heart → arteries) now has high O₂ (100) and low CO₂ (40).

• When this oxygen-rich blood reaches tissues, the tissues are low in O₂ and high in CO₂ because they are constantly using oxygen and producing carbon dioxide.

• So O₂ diffuses from blood to tissues and CO₂ diffuses from tissues to blood (internal respiration).

Blood returning to the right heart (veins → vena cava) now has low O₂ (40) and high CO₂ (45–50) again, completing the cycle.

 

 

 

At rest:

• Blood arriving at the lungs has low O₂ (40) and high CO₂ (45).

• In the alveoli, air has high O₂ (105) and low CO₂ (40).

• Because of these differences, O₂ diffuses into the blood and CO₂ diffuses out (external respiration).

• Blood leaving the lungs (pulmonary veins → left heart → arteries) now has high O₂ (100) and low CO₂ (40).

• When this oxygen-rich blood reaches tissues, the tissues are low in O₂ and high in CO₂ because they are constantly using oxygen and producing carbon dioxide.

• So O₂ diffuses from blood to tissues and CO₂ diffuses from tissues to blood (internal respiration).

• Blood returning to the right heart (veins → vena cava) now has low O₂ (40) and high CO₂ (45–50) again, completing the cycle.

Describe how oxygen and carbon dioxide are exchanged between the lungs, blood, and body tissues during exercise. (including exact values)

At exercise:

• Blood arriving at the lungs during exercise has very low O₂ (~20–30) and high CO₂ (~50–60) because muscles are using huge amounts of oxygen and producing lots of CO₂.

• In the alveoli, ventilation increases, so air has high O₂ (~105) and low CO₂ (~35–40) or even lower.

• Because of these differences, O₂ diffuses into the blood rapidly and CO₂ diffuses out even faster (external respiration).

• Blood leaving the lungs (pulmonary veins → left heart → arteries) still has high O₂ (~100) and low CO₂ (~38–40) because the lungs keep up with demand.

• When this oxygen-rich blood reaches actively contracting muscles, the tissues are extremely low in O₂ and very high in CO₂ due to intense metabolism.

• So O₂ diffuses from blood to tissues even more strongly, and CO₂ diffuses from tissues to blood at a higher rate (internal respiration).

• Blood returning to the right heart (veins → venae cava) now has very low O₂ (~20–30) and high CO₂ (~50–60) again, completing the exercise cycle.

when is breathing in and breathing out passive or active?

• inspiration rest = active

• expiration rest = passive

• inspiration exercise = active

• expiration exercise = active

what happens during inspiration at rest?

• Diaphragm flattens and moves down  

• External intercostal muscles contract 

• Rib cage moves up and out  

• Volume of thoracic cavity increases  

• Pressure of thoracic cavity decreases  

• Air moves from higher pressure outside to lower pressure in the lungs 

what happens during expiration at rest?

• Diaphragm relaxes and returns to a dome shape  

• External intercostal muscles relax 

• Rib cage moves down and in  

• Volume of thoracic cavity decreases 

• Pressure of thoracic cavity increases 

• Air moves from higher pressure to lower pressure outside lungs  

• This process is passive. 

what happens during inspiration during exercise?

• The diaphragm contracts and flattens more than at rest  

• External intercostal muscles contract more that at rest  

• Additional muscles are recruited: sternocleidomastoid, scalene and pectoralis major 

• Rib cage moves up and out further than at rest 

• Volume of thoracic cavity increases more than at rest 

• Pressure of the thoracic cavity decreases more than at rest 

• More air than at rest moves from higher pressure outside to lower pressure in the lungs.  

 

what happens during expiration during exercise?

• The diaphragm relaxes  

• External intercostal muscles relax 

• Additional muscles are recruited: rectus abdominus, external obliques, internal obliques contract 

• Rib cage moves down and in further than at rest 

• Volume of the thoracic cavity decreases more than at rest  

• Pressure of the thoracic cavity increases more than at rest  

• More air moves from higher pressure outside to lower pressure in the lungs