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If Patmos > Palveolar then air will (enter/leave) the lungs?

Enter. Air will travel down the concentration gradient during Inspiration.


The chest wants to (collapse/expand), but the lungs want to (collapse/expand). Therefore the ...... space is ....... in pressure at rest.

Chest wants to expand, but the elastic nature of the alveolar makes them want to collapse. Therefore the intrapleural space is sub-atmospheric in pressure at rest.


What is compliance?

Lungs ability to stretch.


What does high compliance mean?

High compliance: Less work is needed to inspire, but have more difficulty expiring. This may be due to the elastic tissue, so recoils less.
e.g. emphysema- larger vol of lungs, so lower alveolar pressure, so air rushes in.
(Think high off nicotine)


What does low compliance mean?

Low compliance: More work needed to inspire
e.g. Pulmonary fibrosis- lungs more rigid less elastic so can't expand so much, so lower pressure gradient. Lower residual capacity.
(Think feeling low as have fibrosis)


Compliance equation?

compliance= Change in Volume/ change in pressure.


What is Alveolar pressure?
Number at rest, inspiration and expiration?

Pressure of air in alveoli.
No airflow: Palv=Patmos, therefore 0.
Inspiration: PalvPatmos, therefore 15.


What is Airway Pressure?
Number at rest, inspiration and expiration? Constant throughout?

Pressure of air in the airways (conducting)
No airflow: same as Palv and Patmos, therefore 0.

Inspiration: Think of gradient from atmospheric to alveolar, where Patmos=0 and Palveolar=-15, starts from around -4 to -12 as go down trachea.

Expiration: Opposite gradient, so 4-12.


What is transpulmonary pressure?

The pressure difference between alveolar and intrapleural space. Always 5.


What is Intrapleural pressure definition?

The difference between the Visceral pleura (inside) and the thoracic Pleura (outside).
Where the pressure across the visceral pleura is constant (Transpulmonary pressure=5) can work out the intrapleural from the alveolar pressure.


What is transmural pressure?
Number at rest, inspiration, expiration?

The pressure between two sides of a wall, In respiration usually refers to pressure across the visceral pleura so between the intrapleural space and airways. (Transpulmonary is an example of this always 5)
further up the airways these change as go down trachea.


Explain inspiration?

Stimulated by the phrenic nerve, the diaphragm contracts. The external intercostals move the ribs out (bucket handle) and the sternum lifts up. (Pump)
Volume of thorax increases, therefore alveolar pressure decreases.
Air rushes in down pressure gradient.


What region on the brain controls the respiratory rhythm?

Medulla Oblongata of the brainstem.
(The dorsal respiratory Group and the Ventral Respiratory Group)


What is the function of the Dorsal Respiratory Group?

Think: "Walk in through the door quietly"
Quiet Inspiration. (expiration is elastic recoil so passive)


What does the DRG innervate?

Phrenic Nerve: Contract Diaphragm
Spinal Nerves: External Intercostals.
Think: "In through the door quietly after Exiting the IC"


What is the function of the Ventral Respiratory Group?

Think: "Venting forcefully"
Controls forced inspiration and expiration


What does the VRG Innervate?

Inspiration: Same as DRG but also Cranial nerves.
Expiration: Spinal nerves: Internal intercostal and abdominal muscles.
Think: "Venting forcefully letting internal feeling out"


What complex causes the basic rhythm of breathing?

Pre- Botzinger Complex in the VRG


What is special about the Pre-Botzinger Complex cells?

It contains pacemaker cells.


What are the three busting patterns of the Pre-Botzinger complex

Eupneic (normal)
Sigh (Higher output, longer intake)
Gasp (short intake)


What are the two types of neuron in the Pre-botzinger complex?

Pacemaker cells, and non pacemaker cells.


What are the two patterns the pacemaker cells can make?

Individual neurons depolarisations summate to create the inspiration and expiration pattern in the Pre-Botzinger Complex.
Spiking: More steady consistant spikes.
Bursting: AP's very close together getting stronger in frequency
just different activity states of the same neurons.


What's the significance of the NALCN channel in the Pre-Botzinger Complex?

It is a sodium leak channel into the neuron. It contributes to the depolarisation. Important for initial slow depolarisation.


Whats the significance of potassium and the Pre-Botzinger Complex?

If high levels of potassium, the resting potential is increased, say -90 to -80mv. Therefore the intensity of bursting is increased, as more depolarised.


Bursting activity depends on which two types of currents?

The persistant sodium channel (I NAP)
The CAN Cation current (I CAN) (calcium dependent cation channel)


Neurons relying on I NAP for bursting can be classified as ....... Whereas those relying on I CAN are.....

Cadmium insensitive
Cadmium sensitive (Cadmium can block these)


Is the DPG and VRG always active?

DRG: It inactivates after inspiration, then the neurones have a period of activity again etc.
VRG: Inacitve during quiet respiration.


What two ions are high inside a general cell, and which two are kept low?

High: K+, PO4^2- (phosphate in ATP etc)
Low: Na+, Cl- (used for signalling in cell)


Rate of ions per s moved, by carriers, channels, and pumps?

Pumps: <100 ions per second (active and conformational change so slow)
Carriers: 100-1000 (conformational change also)
Channels: 10^6-10^8


How are pumps, carriers, and channels controlled?

Channels: can be gated, either voltage, mechanically, ligand
Pump: Active so controlled by ATP- hydrolyses
Carriers: Controlled by other ions also e.g. NKCC2, needs Na, K and 2 Cl.