Resp Lecture 4 ☁️🌪

Question 1

RECOIL FORCE

Answer 1

ELASTICITY

SURFACE TENSION

Question 2

Defining Elasticity

Answer 2

Ability to recover original size & shape after deformation

Question 3

How Does Expiration Occur at Rest?

Answer 3

RECOIL FORCE
ELASTICITY of the Lungs
Lungs are Distensible
Inspiration Expiration

Question 4

COMPLIANCE

Answer 4

1/ Elasticity

Question 5

COMPLIANCE =

Answer 5

change in Volume/ change in Pressure

Question 6

What is Surface Tension

Answer 6

Molecules within a liquid have cohesive forces with all neighbouring atoms. But, those on the surface (i.e. at a liquid- gas interface) have no neighbouring atoms above, and so exhibit stronger attractive forces upon their nearest neighbours on the surface. This enhancement of the intermolecular attractive forces at the surface is called surface tension.

Question 7

Laplace’s Law

Answer 7

P = 2T/R

Question 8

COPD

Answer 8

Massively expanded lungs
Flattened diaphragm
Mid-sternal space reduced

Question 9

Fibrosis

Answer 9

Deflated lungs Mid-sternal space wide Fluffy areas fibrotic tissue

Question 10

COPD

Answer 10

chronic obstructive pulmonary disease

Question 11

Parasympathetic Nerves

Answer 11

Contained within the vagus nerve Bronchoconstriction Muscarinic receptor

Question 12

Sympathetic Nerves

Answer 12

From the spinal cord Bronchodilator Beta-adrenoceptors

Question 13

Asthmatics take

Answer 13

salbutamol - beta-adrenoceptor agonist

Question 14

Lung stretch

receptors

Answer 14

mechanoreceptors

in bronchioles

Question 15

Hering-Breuer Reflex

Answer 15

SENSORY RECEPTOR lung stretch receptor = Vagal afferents = Medulla Oblongata respiratory centres = Sympathetic efferent= EFFECTOR or TARGET ORGAN = bronchioles: BRONCHODILATE NA –β-adrenoceptor

Question 16

At rest, expiration is a passive process relying on

Answer 16

radial traction which depends on physical properties of the lungs (elasticity and surface tension)

Question 17

La Place’s law To measure the surface tension induced pressure within the alveoli (PA) we 2T use La Place’s law where

Answer 17

PA = 2 x surface tension divided by the alveolar P =

Question 18

Lung compliance

Answer 18

change in volume of lung divided by change in pressure and tends to collapse lungs at functional residual capacity (FRC)

Question 19

Pulmonary disease states typically afect compliance of the lung and/or chest wall: e.g

Answer 19

chronic obstructive pulmonary disease or COPD (increased lung compliance caused by smoking) and ibrosis (“stif lung” caused by air contaminants).

Question 20

The upper tree

Answer 20

irst 16 generations are non-respiratory in function and form the conducting zone – which makes up anatomical dead space

Question 21

Dead space causes contamination of freshly inhaled air diluting the oxygen content. It is approximately 2.2 ml per kg. The respiratory zone (or unit) comprises

Answer 21

respiratory bronchioles, alveolar duct and alveolar sac. These latter structures are free of cartilage and are kept open by the lung parenchyma.

Question 22

Cross sectional area and air low down the airway The cross sectional area increases from the trachea to the alveoli x500 - so called

Answer 22

funnel efect”.

Question 23

300 million alveoli. The low of air in the conducting zone is rapid and

Answer 23

highly turbulent but becomes slow and laminar in the respiratory zone due to large surface area.

Question 24

Airway resistance is dependent on

Answer 24

airway resistance

Question 25

The highest is in the upper airway and lowest in the bronchioles. Airway resistance is dependent on lung volume a inlating the lung pulls airways open via radial traction. The airways contain smooth muscle and are innervated

Answer 25

by parasympathetic (PS) and sympathetic nerves. The PS nerves cause bronchoconstriction and the sympathetic nerves bronchodilatation

Question 26

The bronchal smooth muscle also has numerous receptors sensitive to humoral and hormonal inluences. The bronchiole smooth muscle contains

Answer 26

beta2- adrenoceptors, which are targeted using agonists in people with asthma, for example.

Question 27

The bronchioles are innervated with sensory stretch receptors that generate action potentials during lung inlation that are

Answer 27

sent to the brainstem

Question 28

This triggers a relex bronchodilatation mediated via the sympathetic nervous system to reduce

Answer 28

airway resistance and facilitates air low into the alveoli.