A&P2 lecture 5. Respiratory- organisation and ventilation

winniesmith1's version from 2017-03-13 10:29

Section 1

Question Answer
What are the 2 integral processes of respiration– external respiration
– internal respiration
what is external respirationIncludes all processes involved in
exchanging O2 and CO2 with the
– Pulmonary ventilation
– Gas diffusion
– Storage and transport of O2 and CO2
– The exchange of dissolved gases
what is internal respiration• Also called cellular respiration
• Involves the uptake of O2 and production of CO2 within individual cells
what is pulmonary ventilationIs the physical movement of air in and
out of respiratory tract
• Provides alveolar ventilation
what is alveolar ventilationthe physical movement of air in
and out of the alveoli
tidal volume1/2 a litre (5 to 6 litres at min at rest) max 200 litres

Section 2

Question Answer
what is boyle's lawDefines the relationship between gas
pressure and volume:
P = 1/V
In a contained gas:
– external pressure forces molecules closer
– movement of gas molecules exerts
pressure on container
how does pressure effect air flowAir flows from area of higher pressure to
area of lower pressure
compliance of the lung• An indicator of expandability
• Low compliance requires greater force
• High compliance requires less force
what is compliance of the lung affected by– Connective-tissue structure of the lungs
– Level of surfactant production
– Mobility of the thoracic cage

Section 3

Question Answer
what is quiet breathing (eupnea)Involves active inhalation and passive exhalation
Costal breathing or shallow breathing– is dominated by ribcage movements
Diaphragmatic breathing or deep breathing– is dominated by diaphragm
Forced breathing (hyperpnea)Involves active inhalation and
• Assisted by accessory muscles
• Maximum levels occur in exhaustion

Section 4

Question Answer
Gas pressure**
atmospheric pressure at sea level760mm Hg /torr
1033.6 cmH20
15 psi
what is air pressurecolumn of air pushing down on you from above
composition of air• Nitrogen (N2) 78.6%
• Oxygen (O2) 20.9%
• Water vapor (H2O) 0.5%
• Carbon dioxide (CO2) 0.04%
What is Henry's lawWhen gas under pressure comes in
contact with liquid:
– gas dissolves in liquid until equilibrium is reached
• At a given temperature:
– amount of a gas in solution is proportional to partial pressure of that gas

Section 5

Question Answer
Gas pickup- red blood cells• Blood plasma can’t transport enough O2 or CO2 to meet physiological needs
• Red Blood Cells
– Transport O2
to, and CO2 from, peripheral tissues
– Remove O2 and CO2
from plasma, allowing
gases to diffuse into blood
oxyhemoglobin saturation curve. % saturation of Hbat 100 PO2. 97.5% Hb is saturated
environmental factors affecting Hb• PO2 of blood
• pH
• Temperature
• Metabolic activity within RBCs
what is the bohr effecthaemoglobin's oxygen binding affinity is inversely related both to acidity and to the concentration of carbon dioxide.

Section 6

Question Answer
Carbon dioxide transportGenerated by aerobic metabolism
• Three pathways for CO2 molecule:
– Dissolve in the plasma
– Bind to haemoglobin
– Converted to H2CO3
What amount of C02 binds to hb93%
H2CO3carbonic acid a weak unstable
acid, H2CO3, known only in solution, and as carbonate salts; it
is present in carbonated drinks, and sparkling wine, but
decomposes to form carbon dioxide and water
Key notes on gas transport– If the PO2 increases, haemoglobin binds oxygen;
– if the PO2 decreases, haemoglobin releases oxygen.
At a given PO2, haemoglobin will release additional oxygen if the pH decreases or the temperature increases.

Section 7

Question Answer
Control of respiration- under normal conditions– Cellular rates of O2 absorption and CO2
production at cells = O2 absorption and CO2 excretion at lungs.
Control of respiration when normality is removed– CVS and respiratory systems must adjust
Local control of respiration at tissuesincrease activity of peripheral tissue
– decrease Po2 & increase Pco2
– Changes in gas exchange
– Increased blood flow
Control centres of brain- voluntary– Reflects activity in
the cerebral cortex
– Affects output of
respiratory centres &
motor neurons
control centres of brain- involuntary– Medulla oblongata &
– Respiratory muscles
– Frequency & depth
– Responding to info
from lungs and
respiratory tract +

Section 8

Question Answer
Respiratory centres• 3 pairs of nuclei in the reticular formation of medulla oblongata and pons
where are the respiratory centres locatedbrain stem
respiratory centres: medulla oblongata: structure/formationApneustic Centres &
Pneumotaxic Centres
•Adjust rate and depth in response to sensory stimuli, emotions or speech
respiratory centres: pons: structure/formationApneustic Centres &
Pneumotaxic Centres
•Adjust rate and depth in
response to sensory stimuli,
emotions or speech
higher centres- brain pathwayCerebral cortex
Limbic system

Section 9

Question Answer
quiet breathing pathwayinhalation (2secs)
Exhalation (3 secs)
Dorsal respiratory group active > inspiratory muscles contract > inspiration occurs > Dorsal respiratory group inhibited > inspiratory muscles relax > Passive expiration occurs.
forced breathing pathwayDRG and inspiratory center of VRG active.
Expiratory center of VRG inhibited. > Inspiratory muscles contract. Expiratory muscles relax. > Inspiration occurs > DRG and inspiratory center of VRG inhibited. Expiratory center of VRG active. >
Inspiratory muscles relax, expiratory muscles contract. > Active expiration occurs.
types of mechanoreceptorsMachanoreceptros and stretch receptors
baroreceptorsin aortic or carotic sinuses:
• sensitive to changes in blood pressure
stretch receptorsRespond to changes in lung volume

Section 10

Question Answer
Aortic sinusbaroreceptor
Chemoreceptors• Chemoreceptors are sensitive to:
– Pco2, Po2, or pH
– of blood or cerebrospinal fluid (CSF)
• Irritating physical or chemical stimuli:
– in nasal cavity, larynx, or bronchial tree
• Other sensations including:
– pain
– changes in body temperature
– abnormal visceral sensations
Hering-breuer reflexes: inflation reflex• prevents overexpansion of lungs
Hering-breuer reflexes: deflation reflex• inhibits expiratory centers
• stimulates inspiratory centres during lung
Chemoreceptor reflexes• Respiratory centers are strongly influenced by chemoreceptor input from:
– cranial nerve IX (glossopharyngeal nerve)
– cranial nerve X (vagus nerve)
– receptors that monitor cerebrospinal fluid
Chemoreceptor stimulationA drop in Po2
to around 40 mmHg
increases respiratory rate by 50 – 70%.
• A rise of 10% in arterial Pco2 will
increase respiratory rate by 100%.
• Chemoreceptor stimulation is subject to
– decreased sensitivity due to chronic
• Increases in lactic acid affect

Section 11

Question Answer
key notes

Section 12

Question Answer
Respiratory changes at birth: before birth– pulmonary vessels are collapsed
– lungs contain no air
Respiratory change at birth: at birthnewborn overcomes force of surface
tension to inflate bronchial tree and
alveoli and take first breath
yayu got this

Section 13