L20 - Control of breathing

Question 1

name for shortness of breath

Answer 1

dyspnea

Question 2

what 3 changes does breathing need to accomodate
and give examples

Answer 2

metabolic - blood gases and pH
mechanical - postural changes
episodic non-ventilatory - speaking, sniffing, eating

Question 3

local control of gas transport - how does inc in CO2 affect blood flow

Answer 3

triggers vasodilation
incerases blood flow
more CO2 removal and more O2 delivery

Question 4

local control of gas transport - lung perfusion

Answer 4

is there’s not much PP of O2 in a certain area in lungs
vasocontriction occurs
so decreases blood flow in that area
but directs blood flow to areas with more O2

Question 5

local control of gas transport - alveolar ventilation

Answer 5

inc CO2
causes bronchodilation
which increases air flow
and directs airflow to areas of high PP of CO2
so it can be removed

Question 6

central control of ventilation - what are the sensors

Answer 6

central and peripheral chemoreceptors

mechanoreceptors (respond to stretch)

Question 7

central control of ventilation - what are the central controllers

Answer 7

resp centres in the pons and medulla

Question 8

central control of ventilation - what are the effectors

Answer 8

muscles of ventilation

Question 9

central chemoreceptors - location and what they repond to

Answer 9

medulla

respond to
- change in pH (acidic conditions)
- hypercapnia (too much CO2)
- no effect of hypoxia, these receptors dont respond to that at all

Question 10

peripheral chemoreceptors - location and what they repond to

Answer 10

aortic and carotid body

respond to
- hypoxia
- hypercapnia
- change in pH

Question 11

mechanoreceptors - location and what they repond to and types

Answer 11

lung receptors

respond to stretch

• rapidly adapting receptors
• slowly adapting receptors
• C-fibres receptors

Question 12

which blood is important to look at when checking levels of CO2, H+ and O2

Answer 12

arterial blood

Question 13

if O2 falls below ____mmHg partial pressure it is a problem

Answer 13

60mmHg
only then will receptors be triggered

Question 14

central chemoreceptors: what nerves are they located close to

Answer 14

VIII and XI cranial nerve
so damage to these can cause resp problems

Question 15

central chemoreceptors: how can they directly be triggered by CO2

Answer 15

CO2 can cross the blood brain barrier

indirectly via its effect on decreasing pH

Question 16

how come the CSF is sensitive to blood pH

Answer 16

its vry weakly buffered
so pH in CSF similar to blood pH

Question 17

peripheral chemoreceptors: where are they

Answer 17

aortic and carotid body

Question 18

peripheral chemoreceptors: what are they innervated by

Answer 18

carotid body:
carotid sinus nerve
which is innervated by
glossopharyngeal (one of our cranial nerves)

aortic body:
innervated by vagus nerve

Question 19

whats the result of too much H+ in the blood from too much CO2?

Answer 19

respiratory acidosis

Question 20

what could be a result of hyperventilation?

Answer 20

decrease in CO2
so incerase in pH
respiratory alkalosis

Question 21

what happens when PO2 is too high (e.g. breathing O2 rich gas mixtures_

Answer 21

could generate free radicals
whcih damages cells
coma and death

Question 22

mechanoreceptors: what reflex is slowly adapting mechanoreceptors related to

Answer 22

Hering Breuer reflex

Question 23

mechanoreceptors: where are the slowly adapting mechanoreceptors found

Answer 23

visceral pleura, bronchioles and alveoli

Question 24

mechanoreceptors: purpose of slowly adapting mecahnoreceptors

Answer 24

prevent overinflation of lungs
trigger exhalation
fires quite slowly (hence the name) cuz we want to be able to breathe in duh, but after a certain point it fires faster

Question 25

mechanoreceptors: what are rapidly adapting stretch receptors responding to and whats the result

Answer 25

respond to irritants
e.g. smoke, dust, cold air etc

cause bronchoconstriction
coughing reflex

Question 26

mechanoreceptors: wehre are rapidly adapting located

Answer 26

airway epithelia

Question 27

mechanoreceptors: where are c fibre receptors located

Answer 27

alveoli wall
and conducting airways

Question 28

mechanoreceptors: what do c fibre receptors respond to and cause

Answer 28

chemical and mechanical stimuli
mainly mechanical
so, left sided heart failure -> cuases engorgemnt of pulmonary caps

triggers recpetors to fire
causing bronchoconstriction
shallow breathing
mucus secretion

Question 29

which central controller located in the medulla

Answer 29

rhythmicity centre

Question 30

what type of breathing does the rhythmicity centre control

Answer 30

automatic breathing
I neurons control inspiration
E neurons control expiration

Question 31

what central controller located in the pons

Answer 31

pneumotaxic and apneustic centres

Question 32

what do pneumotaxic and apneustic centres do

Answer 32

modify firing pattern of medullary centres#

not involved in normal resp
only when increased demand
so it’ll promote inspiration and stuff

Question 33

in rhytmicity centre, where are I neurons located

Answer 33

dorsal respiratory group

Question 34

in rhytmicity centre, where are E neurons located

Answer 34

ventral respiratory group
(contains some I neurons too but whatever)

Question 35

what do I neurons regulate

Answer 35

the phrenic nerve
which then innervates the diaphragm
so it stimulates muscles of quiet inspiration

Question 36

what do E neurons regulate

Answer 36

expiration is a passive process (elastic recoil)
but
E neurons will inhibit I neurons

Question 37

how do you calculate ventilation rate

Answer 37

VR = tidal volume x respiratory rate (f)