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Body Systems Y1 > Body Systems L18 Notes > Flashcards

Body Systems L18 Notes Flashcards

1
Q

Define pulmonary ventilation

A

• Pulmonary Ventilation:

- Physical movement of air into & out of the respiratory tract

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2
Q

What are the functions of pulmonary ventilation

A
  • Function:
     Ensure continuous oxygen supply
     Prevent accumulation of CO2
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3
Q

What two principals govern pulmonary ventilation?

A

 Boyle’s Law:

 Air flows from area -> high pressure to low pressure.

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4
Q

Outline Boyle’s Law

A

 Boyle’s Law:
 The pressure of a given quantity of gas is inversely proportional to it’s volume.
 Decr. Vol -> Incr. pressure
 Incr. Vol -> Decr. pressure

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5
Q

Outline the principal  Air flows from area -> high pressure to low pressure.

A

 Air flows from area -> high pressure to low pressure.
 Incr. volume -> decr. pressure
&raquo_space; Air moves in
 Decr. volume -> incr. pressure
&raquo_space; Air expelled

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6
Q

Describe the movement of air during different conditions in pulmonary ventilation

A

• Ventilation:
- Atmospheric pressure > Intrapulmonary / Intraalveolar pressure
 Air enters lungs
- Intrapulmonary / intraalveolar pressure > atmospheric pressure
 Air expelled from lungs
- Change -> volume = change -> pressure

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7
Q

What is the normal value for atmospheric pressure?

A
  • Atmospheric pressure = 760mmHg
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8
Q

What factors influence incr. thoracic volume?

A
  • Incr. Vertical diameter
  • Incr. Anterior Posterior diameter
  • Incr. transverse diameter
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9
Q

Describe the influence of incr. vertical diameter on incr. thoracic volume

A
  • Incr. Vertical diameter
     Contraction of diaphragm incr. vertical diameter
    Responsible for 75% incr. thoracic capacity
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10
Q

Describe the influence of - Incr. Anterior Posterior diameter on incr. thoracic volume

A
  • Incr. Anterior Posterior diameter
     Elevation of ribs incr. Anterior Posterior diameter
    -> (Joint with Transverse Diameter)
    Responsible for 25% thoracic capacity.
     Elevation of ribs -> external end -> makes them more horizontal & pushes sternum forward (pump handle movement)
    Incr. AP diameter
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11
Q

Describe the influence of Incr. transverse diameter on incr. thoracic volume

A
  • Incr. transverse diameter
     Elevation of ribs incr. transverse diameter
    -> (Joint with Transverse Diameter)
    Responsible for 25% thoracic capacity.
     Many of the ribs
     Lowest near their middle
     Rise at each end
    Eg. Bucket handle
     Rise of middle of rib -> movement away from midline of body
    Transversally widens chest (Left -> Right)
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12
Q

Describe the role of the pleura in ventilation

A

• Role of Pleura in Ventilation:
- Surface tension created by film of serous fluid between Parietal & Visceral pleura
Prevents pulling apart
- Incr. volume of thorax causes incr. volume of lungs.

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13
Q

Describe the intrapleural pressure

A
  • Inrapleural pressure:
     Pressure within pleural cavity
     Always lower than atmospheric & intrapulmonary pressures
     Created -> Elastic recoil of lungs
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14
Q

Describe the influence of pneumothorax on ventilation

A
  • Pneumothorax:
     Accumulation -> Air / gas in pleural cavity
     Disease / injury -> Eg. Puncture Wound
     Loss of negative intapleural pressure (approx. 760mmHg)
     Lung collapse
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15
Q

What kind of process is inspiration? Is it the same at both rest & when forced?

A

Active -> Both at rest & when forced

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16
Q

Describe inspiration at rest

A
  • At rest:
     Diaphragm (75%)
     External intercostal muscles (25%)
     Contracted diaphragm flattens
    -> Vertical diameter of thorax increased.
     External intercostals elevate ribs -> incr. Anterior Posterior & Transverse
    diameters.
17
Q

Describe inspiration when it is forced

A 
-	Forced:
	Pectoralis major 
	Pectoralis minor
	Scalenes
	Serratus anterior
	Sternocleidomastoid
 Assist -> rib elevation 
    -> Incr. speed & amount of movement
18
Q

What kind of process is expiration? Is it the same at both rest & when forced?

A

Passive at rest

Active when forced

19
Q

Describe expiration at rest

A 
-	At rest:
	Passive process
	Diaphragm 
	External intercostals
 Relaxation of diaphragm & external intercostal muscles
20
Q

Describe expiration when it is forced

A 
-	Forced:
	Active process
	Internal intercostals
	Abdominal muscles
-> Rectus abdominis 
-> External oblique 
-> Internal oblique
-> Transversus abdominis
 Internal & innermost intercostals depress ribs 
    -> Reduce size of thoracic cavity
 Abdominal muscles compress abdomen & force diaphragm upwards
21
Q

List the abdominal muscles involved in forced expiration

A

 Abdominal muscles

  • > Rectus abdominis
  • > External oblique
  • > Internal oblique
  • > Transversus abdominis
22
Q

Describe neural control of ventilation

A

• Neural Control of Ventilation:
- Chemoreceptors detect changes in PO2, PCO2 & pH
-> Send impulses / signals
 Vagus (CN X) & Glossopharyngeal (CN IX) nerves
(Afferent pathway)
- Impulses transported -> Vagus (CN X) & Glossopharyngeal (CN IX) nerves
 Respiratory Centres of Brain Stem
- Respiratory Centres of Brain stem
-> Send impulses / signals
 Phrenic, intercostal & other nerves
(Efferent pathway)
- Impulses transported -> Phrenic, intercostal & other nerves
 Muscles in ventilation

23
Q

Describe the central chemoreceptors

A

• Central Chemoreceptors:

  • Located -> Medulla oblongata of brainstem
  • Respond to changes in PCO2 & pH
24
Q

Describe the peripheral chemoreceptors

A 
•	Peripheral Chemoreceptors:
-	Detect changes -> PO2, PCO2 & pH
-	Aortic Bodies
 Located -> Aortic Arch
 Innervated -> Vagus (CN X)
-	Carotid Body
 Located -> Common Carotid Artery
 Innervated -> Glossopharyngeal (CN IX)
25
Q

Where are the aortic bodies of the peripheral nerve located & what are they innervated by?

A
  • Aortic Bodies
     Located -> Aortic Arch
     Innervated -> Vagus (CN X)
26
Q

Where are the carotid body of the peripheral nerve located & what are they innervated by?

A
  • Carotid Body
     Located -> Common Carotid Artery
     Innervated -> Glossopharyngeal (CN IX)
27
Q

Describe the respiratory centres of the brain

A

• Respiratory Centres:
- Group of neurons -> Brain stem
- Send impulses to muscles of ventilation
- Medullary Rhythmicity Area
 Dorsal Respiratory Group (DRG)
 Sets rhythm, stimulates muscles of quiet inspiration
 Ventral Respiratory Group (VRG)
 Involved in forced inspiration & expiration
- Pneumotaxic area (Pons)
 Influences DRG by regulating duration of inspiration.

28
Q

Name the two areas of the respiratory centres

A
  • Medullary Rhythmicity Area

- Pneumotaxic area (Pons)

29
Q

What is the function of the medullary rhythmicity area of the respiratory centre

A
  • Medullary Rhythmicity Area
     Dorsal Respiratory Group (DRG)
     Sets rhythm, stimulates muscles of quiet inspiration
     Ventral Respiratory Group (VRG)
     Involved in forced inspiration & expiration
30
Q

What is the function of the Pneumotaxic area (Pons)of the respiratory centre

A
  • Pneumotaxic area (Pons)

 Influences DRG by regulating duration of inspiration.

31
Q

Describe the Hering-Breuer Reflex

A 
•	Hering-Breuer Reflex:
-	Prevents over-inflation of lungs
-	Stretch receptors 
 Visceral pleura
 Bronchioles
 Alveoli 
-	Impulses sent via vagus nerve 
 Pneumotaxic centre
-	Duration of inspiration shortened.
32
Q

Outline the pathway involved in neural control of ventilation

A

Chemoreceptors -> Vagus (CN X) & Glossopharyngeal (CN IX) nerves -> respiratory centres of brain -> Phrenic, intercostal & other nerves -> Muscles in ventilation

Body Systems Y1 (22 decks)

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