week 9- control of gas ventilation

Question 1

name the primary sensory receptor

Answer 1

chemoreceptors

Question 2

what are chemoreceptors sensitive to

Answer 2

co2 changes
o2 changes

Question 3

where are chemoreceptors found

Answer 3

aortic arch
carotid arteries
medulla oblongata

Question 4

where do respiratory centres also receive their information from (other sensory inputs)

Answer 4

proprioceptors
cerebral cortex
hypothalamus
lungs-stretch and irritant receptors

Question 5

Function of Ventral respiratory group

Answer 5

Sets basic rhythm at rest- tidal volume

Question 6

Where does Ventral respiratory group out put

Answer 6

Phrenic nerve
Intercostal nerve

Question 7

Function of Dorsal respiratory group

Answer 7

Integrates receptor information and modifies VRG

Question 8

Function of pontine respiratory centres

Answer 8

Fine tunes breathing rhythm.
Smooths out normal breathing and modifies during activity
E.g. talking, sleep

Question 9

What occurs In external respiration

Answer 9

Exchange of O2 and CO2 between alveoli and blood in pulmonary capillaries

Question 10

Explain what occurs internal respiration

Answer 10

Exchange of O2 and CO2 between cells in tisssues and systenuic capillaries

Question 11

Describe Daltons Law

Answer 11

The total pressure in a mixture of gases is the sum pressure of the individual gases. The pressure of each gas in a mixture is known as the partial pressure

Question 12

What is the total pressure in a mixture

Answer 12

The sum of the pressure of the individual gases

Question 13

Describe partial pressure

Answer 13

Pressure of each gas in a mixture

Question 14

What can influence the shape of haemaglobin

Answer 14

Pao2, Paco2, temperature, blood ph

Question 15

Describe a hb molecule

Answer 15

-4 globin protein linked together
-each globin protein forms a haem group with an Fe2+
-Fe2+ binds to oxygen it become Fe3+
-each hb can carry 4 o2 molecules

Question 16

When does hb shape change

Answer 16

When o2 bind

Question 17

Describe hb in a low o2 state

Answer 17

-molecule is TENSE
-crevice for 02 to move through is small
-o2 affinity is low

Question 18

Describe hb in a high o2 state

Answer 18

-RELAXED molecule
-crevice for o2 to bind is large
-o2 affinity is high

Question 19

How does the addition of each o2 molecule effect hb

Answer 19

-each time an o2 bind, hb becomes more RELAXED position
-called CO-OPERATIVE BINDING

Question 20

Why is the hb graph (PaO2, Percent o2) ‘S’ shaped?

Answer 20

CO-OPERATIVE BINDING
The addition of an O2 molecule changes hb shape to help the binding of the next molecule
-at top of graph, curve flattens as all o2 binding sites are taken. Low o2 affinity. Releases o2 where o2 levels are low
-high o2 levels, affinity of o2 binding increases , reloading takes place

Question 21

When is the affinity for o2 low

Answer 21

When o2 levels are low (in tissues)

Question 22

How saturated does venous blood return from the body

Answer 22

75% at rest
1 binding site is used

Question 23

What offers protection to a loss of ventilation

Answer 23

-o2 is around 13.3kpa in alveoli
-Hb is nearly fully saturated at 10.6kpa
-offer protection to a ventilation loss

Question 24

How would normal saturations lower than 90-% effect the hb graph

Answer 24

Graph is steeper
Potentials for large desaturation to small o2 changes in body

Question 25

What other factor effects the way hb carrieso2

Answer 25

• H+ from CO2 binds with globin molecules and promotes TENSE SHAPE

Question 26

what carries co2 in the blood

Answer 26

-bicarbonate (70%)
-bound toHb(23%)
-dissolved in plasma (7%)

Question 27

Describe gas transport of co2 from tissues to lungs

Answer 27

-co2 moves down conc gradient into plasma of blood
-co2 moves down conc gradient to rbc where it binds with water
-water and co2 for a weak acid called CARBONIC ACID
-carbonic acid DISSOCIATES into BICARBONATE and H ions.
-bicarbonate diffuse out rbc to plasma
-H + bind to proteins of rbc and promotes TENSE STATE and release of O2

Question 28

Describe has transport of CO2 from RBC to the lungs

Answer 28

-BICARBONATE ions diffuse back to RBC
-Bicarbonste and H+ ions re-join to form CARBONIC ACID
-carbonic acid DISSOCIATES into co2 and water and H+
-CO2 move down conc gradient to plasma
-co2 diffuses down partial pressure gradient into alveoli where it is ventilated into outside air
-reduces partial pressure of co2 in the lung as sets up gradient that starts the process

Question 29

describe what happens to co2 and o2 when you hold ur breath

Answer 29

co2 rise
o2 fall

Question 30

how are o2 and co2 monitored in blood

Answer 30

chemoreceptors in aortic branch, carotid artery and medulla monitor levels of o2 and co2 (H+ ions)

Question 31

why are u unable to hold your breath indefinitely

Answer 31

chemoreceptors are stimulated by rising co2 and signal DORSAL RESPIRATORY GROUP in respiratory centres of medulla oblongata
DRG has conscious input from cerebral cortex which inhibits normal breathing control during breathing. frequency of AP increase as co2 increases, vertebral cortex is over ridden and DRG eventually send signals to VRG to increase breathing rate and depth to respiratory muscle of breathing (diaphragm, external)

Question 32

what is breath holding activities i.e. singing, talking controlled by

Answer 32

pneumotaxic/pontine respiratory group

Question 33

how is blood normally around ph 7

Answer 33

H+ ions during transit of CO2 tpo the lungs is buffered by the non bicarbonate buffering system, mainly Hb, preventing reduction in PH. as the amount of ventilated CO2 matches rate of production the partial pressure of co2 remains constant

Question 34

how is blood ph 7 when exercising

Answer 34

co2 increases massiveley. chemoreceptors are sensitive to both changes in partoial pressure of CO2 and level of free H+ ions, ventilation is increased to match rate of production.

Question 35

how does blood ph fall with ventilation failure

Answer 35

co2 is unable to be removed from blood as a direct result of this limitation in ventillation. it accumulates in blood rising and partial pressure of co2 rises.
CO2 + H20 > H2C03 + H+
equation moves right and more H+ made, more acidic

Question 36

why is oxygen carraige expressed as percentage saturation (SpO2%)

Answer 36

it is carried by HB there are a finite number of carrying molecules and finite amount of o2 carrying ability. total number of occupied binding istes can be expressed as a percentage

Question 37

define relaxed and tense hb states
decsribe cooperative binding in Hb

Answer 37

binding of o2 facilitates further binding for o2 molecules and vice versa. in the lungs where o2 is high, binding of one o2 molecule to one binding site promotes relaxed states in other binding sites, making binding of the next oxygen molecule easier. in low o2 areas (respiring tissues), o2 is lost promoting the tense states in other binding sites, reducing its affinity for o2, promoting its release to these tissues.

Question 38

rbc pass through well ventoilated alveoli..

Answer 38

relaxed

Question 39

rbc pass through muscle during high aerobic exercise…

Answer 39

tense