PP and neural regulation Flashcards
How is blood transported in the body?
- 97% in the blood combined with haemoglobin (as oxyhaemoglobin)
- 3% dissolved in plasma
Where does external respiration take place?
in the alveoli
How is the structure of alveoli designed to help gaseous exchange?
- tin walls mean short diffusion pathway
- huge SA allows greater O2 uptake
- extensive capillary network round alveoli provides an excellent blood supply
How does PP affect O2 movement in external respiration?
- PP of O2 in the alveoli is higher than in the capillaries
- capillary PP is lower as O2 has been removed from the muscles
- difference in PP is referred to as concentration/ diffusion gradient
- the bigger the gradient the faster the diffusion rate
- O2 will diffuse from the alveoli into the blood until pressure is equal in both
How does PP affect O2 movement in external respiration?
- CO2 movement occurs in the opposite direction to O2 movement
- PP of CO2 entering the capillaries is higher than in the alveoli
- CO2 diffuses into the alveoli from the blood until pressure is equal
How does PP affect O2 movement in internal respiration?
- capillary membranes surrounding the muscles have a higher PP of O2 than in the muscles
- allows O2 to diffuse from the blood into the muscle until equilibrium is reached
How does PP affect O2 movement in internal respiration?
- PP of CO2 in the blood is lower than in the muscles
- diffusion occurs and CO2 moves into the blood to be transported to the lungs
What is the oxyhaemoglobin dissociation and what does it show?
- represents the relationship between O2 and haemoglobin
- S shaped curve
- at rest PP of O2 in the lungs means haemoglobin is almost completely saturated with O2
- in the tissues PP of O2 is lower therefore haemoglobin gives up some of it’s O2 to the tissues
What three factors cause the Bohr shift?
- decrease in blood PH
- increase in blood temperature
- increase in blood CO2
What happens during the Bohr shift?
- additional O2 released from haemoglobin at lower PH (higher CO2 concentration)
- in the tissue there is a lower PP of O2 and high PP of CO2
- haemoglobin unloads meaning even more O2 is released to the tissues
What is breathing rate controlled by and how?
RCC (respiratory control center) located in medulla oblongata
sympathetic nervous system = increases breathing rate
parasympathetic nervous system = decreases breathing rate
controls rate and depth of breathing to increase tidal volume using neural and chemical control
What is the inspiratory center and what is it controlled by?
inspiratory center = at rest responsible for rhythmic cycle of breathing
nerve impulses are generated via the intercostal nerve, to external intercostals and the phrenic nerve to the diaphragm in order for them to contract
controlled by the RCC
How is breathing rate, depth and rhythm increased during exercise?
- blood acidity increases due to increased CO2 in the blood (detected by chemoreceptors)
- impulse is sent to the RCC to the IC
- breathing rate is increased by recruiting additional inspiratory muscles (sternocleidomastoid and pectoralis minor) until blood acidity returns to normal
When are stretch receptors activated and what do they do?
activated = when breathing is deeper and the lungs are stretched further
prevent over inflation of the lungs by sending impulses to the EC which stimulates expiratory muscles so expiration occurs
What are the impacts of physical exercise on the respiratory system?
- strengthened respiratory muscles resulting in deeper breathing
- increased gaseous exchange occurs so more O2 diffuses into the blood and more CO2 from the blood
- increased tidal volume and minute ventilation allowing more O2 to diffuse into the muscles and CO2 out
- improved efficiency of respiratory system so the body can supply with more O2 due to an increase in SA and capillary density of alveoli
