B2- Control Of Breathing

Question 1

What is minute ventilation litees per minute

Answer 1

5L per min

Question 2

What is maximum minute ventilation eg in exercise

Answer 2

125-175 L per min = ventilatory reserve

Question 3

What is arterial ph at usuallt unless resp acidosis or alkilosis

Answer 3

7.35-7.45

Question 4

If alveolar p02 is around 159, what is arteiral

Answer 4

Around 100 mm hg (40 in tissues)

Question 5

Ppco2 is lower in arrtial than tissues. Around what

Answer 5

35-40 compared to 46 mm hg in tissues

Question 6

At sea lecel what is toral mmhg bsrometeic oressure

Answer 6

760 (around 160 for o2/21%)

Question 7

What is the p h20 (humidity constant) which redcues the 760mmhg and therefore reduces p02 in alceoli too

Answer 7

47 = 713 mmhg instead

Question 8

If o2 is arounr 21% of baromemetric pressure what is it includin humidity

Answer 8

150 vs 159 if not humid air

Question 9

Since barometric pressure decreases when go ip in altitude whag also decreases

Answer 9

P02

Question 10

When do hb on dissocion curve get to 75% saturation (wuite tolerant of low mmhg)

Answer 10

40mmhg (venous blood)

Question 11

Where does it start to rapidly dissoxate

Answer 11

At tissues eg around 50% dissocation when at p02 of 27

Question 12

Why is saturation at wuite low altitudes good for

Answer 12

People living in high altitude as you sont wanr dissocation without pick up

Question 13

How does co2 affect dissociation

Answer 13

Infeeases if it reacts with h20 and then forms h and hco via carbonic anhydrase

H binds hb and causes taut state (deox) instwad of relaxed (bohr effect)

Question 14

What is the respiratory centre of control

Answer 14

Medulla oblongata in brsin stem

Question 15

What sort of signals do they get (afferent)

Answer 15

Chemoreceptor signals, proprioceptors, stretch recetors, irritant

Question 16

Where are the main chemoreceptors

Answer 16

Central. They ste in medulla

Question 17

What are drg neurones (during quiet)

Answer 17

Mainly inspiratory. They send signals eg down ohrenic to diaphragm snd then external intercostals too

Question 18

Bow do inputs fet to drg

Answer 18

Vagus and IX mainly

Question 19

What are vrg in ONLY sctive resp

Answer 19

Both insp and exp neurones eg to pahrynx larynx diaphragm and external intercostals

Then internal and abdomjnals for expiration

Question 20

What does rhe pons do

Answer 20

Modify outputs by the medulla

Question 21

What do central mainly snese

Answer 21

Co2, ph

Question 22

What can cross from blood freely to csf reaching central chemorecetors

Answer 22

Co2

Question 23

What does co2 react with ti form the h and hco (h does this) which allows centrak to respond

Answer 23

H20 and carbonic anhydrase reaction

Question 24

What does co2 have to be above to cause central chemo to upreg ventilation

Answer 24

40 mm hg (sensitive ti hypercapnia)

Question 25

What cant cross freelyb

Answer 25

H and HCO

Question 26

Which layer of endothelial acts as the bbb shrrounding capillaries

Answer 26

Choroid plexus

Question 27

How does cp allow transport of ions like hco, na and cl across their villi into ventrciles (cerebral ventricles)

Answer 27

Acgive transport. Not free movemrnt

Question 28

Why cant central control resp acidosis and what does detect it

Answer 28

Cant detect ph as well in the blood as well(limited to csf). Peripheral detect co2 to an extent too = stop acidosis

Question 29

Peripehrral detecting o2 are not sensitive. At what o2 legel do they respond

Answer 29

Below 60mmhg

Question 30

What % of respiratory drive do they have for co2/ph eg in acidosis

Answer 30

20%. It is weak stimulating

Question 31

Are rhey essential

Answer 31

No

Question 32

Where are cwrotid bodies and what do they send impulses down

Answer 32

Carotid sinus. Send down ix

Aortic down x

Question 33

What happens at high o2 to peripheral

Answer 33

Switch off and centilation stops for abit till ph lwoers and central can respond

Question 34

How do type1 glomus cells in carotid body respond

Answer 34

Detect low o2 and causes k channels to close. This causes depolarisation and ca floods in.

Ca flooding causes dopamine release down ix