Breathing Flashcards
What i pulmonary ventilation?
Change in lung and gas pressure, that is brought about by the nervous system controlling inspiration and expiration.
How is the basic rhythm for breathing controlled?
controlled by the autonomic nervous system and modified by voluntary influences and reflexes, e.g. sneezing
What is the control centre for breathing?
Medullary respiratory centres. Which are neurons in the medulla ablongata. Which is modified by the pons in the brainstem.
What are the two main neurons in the medulla?
Dorsal respiratory group (DRG)
Ventral respiratory group (VRG)
What is the Dorsal respiratory group (DRG) and what effect does it have?
Neurons in the medulla that control breathing.
Works with and modifies the Ventral respiratory group (VRG)
What is the ventral respiratory group and what effect does it have?
Neurons in the medulla that control breathing.
stimulates breathing by cyclical burst of nerve impulses.
Coordinating rate and rhythm
How does the body switch from inspiration to expiration?
The Dorsal respiratory group DRG and Ventral respiratory group (VRG) ‘switch off’ decreasing impulses causing the respiratory muscles to relax and start expiration.
What are the Neurons in the pons that regulate breathing and how do they achieve it?
Pontine respiratory group (PRG)
Inhibits the duration of inspiration by modifying medullary inspiration neurons DRG and VRG
What ensures the lungs do not over inflate?
Stretch receptors
how does the diaphragm effect breathing?
Supports breathing by flattening, which pulls on the pleural membrane of the lungs, increasing lung potential volume. This also by increasing the space available in the thoracic cavity.
This is controlled by the phrenic nerves
How do the intercostal nerves effect breathing?
they stimulate the intercostal muscles to move the rib-cage and sternum to move up and out.
Due to the attachment of the plural membrane this increases lung volume
why is The pressure in the plural layers always lower then the intrapulmonary pressure (in alveoli)?
To help prevent to collapse of alveoli and to reduce the effort of breathing
What is the surfactant in the lungs?
A layer of water molecules within the alveoli that aids the diffusion of gases, due to the reduced surface tension.
this lowers the effort needed for breathing
Tidal volume
the volume of gases exchanged during normal respiration. 500ml
Inspiratory reserve volume:
the volume of air that can be taken in forceably above the tidal volume (2100-3200ml)
Expiratorary reserve volume:
The volume of air that can be expired out forceably above the tidal volume (1200ml)
Residual volume?
The volume of air that is left in the lungs after forceably exhaling. , prevents collapsing and ensure lung elasticity
Factors that influence the exchange of gases across the respiratory membrane:
- pressure gradient.
- Solubility (effected by temp)
- Effectiveness of blood flow
- how thin the respiratory membrane is.
Steps of inhalation phase:
- Contraction of diaphragm and intercostal muscles - creating thoracic and lung space.
- lowered interpulmanary pressure creates a concentration gradient approx 1mmHg. between Atmosphere>alvioli.
- air flows doing pressure gradient until balanced.
Steps of expiration phase
- DRG & VRG ‘switch off’ impulses and diaphragm and intercostasl muscles causing them to relax reducing thoracic space and lung size.
- increased pulmonary pressure creates a Alvioli>atmosphere gradient
- air flows out the lungs to the atmosphere.
Regulation of breathing negative feedback loop:
Stimulus: rise CO2&H+ drop in pH.
receptors: chemoreceptors and cardinoid bodies.
afferent pathway: increases
control cente: DRG VRG in the medullary respiratory centre.
effecent pathway: increase in phrenic nerve impulses and intercostal nerve.
effectors: inhalation & exhalation increasing in force and frequency. increases: tidal volume, RR, ventilation.
