Respiration: Regulation

Front 1

location of respiratory center

Back 1

-widely dispersed neurons in:
1. medulla oblongata
2. pons

Front 2

components of respiratory center

Back 2

1. inspiratory and expiratory groups
2. pneumotaxic center or CPG
3. apneustic center

Front 3

inspiratory and expiratory groups fx

Back 3

neurons generate respiratory rhythm
- inspiratory neurons dominate
- expiratory neurons only fire when respiratory drive increases

Front 4

pneumotaxic center or central pattern generator (CPG) fx

Back 4

terminates the inspiration
- determines the length of inspirations and therefore respiratory rate

Front 5

apneustic center fx

Back 5

- not completely clear
- extreme circumstances: prevents of retards the switch off function of the pneumotaxic center

Front 6

Inspiration

Back 6

- active: begins when inspiratory groups generate a small signal that causes i mm to contract
- contraction strength depends on signal strength: freq of APs
-

Front 7

inspiratory ramp signal

Back 7

- inspiratory groups generating and increasing rate of APs
- cut of by pneumotaxic center at end of inspiration

Front 8

expiration

Back 8

- passive relaxation of inspiratory mm
- when more air required to meet the demands of tissues, passive relaxation too slow and expiratory mm contract
- expiratory mm contraction puts P on the thorax and thus accelerates air flow out of the lungs

Front 9

regulation via gaseous concentrations

Back 9

- of O2 and CO2 in blood and alveolar air
- duration of inspiration and tidal volume adjusted to maintain:
PO2 104, PCO2 40
- stretch receptors in inspiratory mm (not diaphragm) also contr

Front 10

stretch receptors in inspiratory mm

Back 10

- stretch receptors in inspiratory mm , except diaphragm, also control the depth of breathing

Front 11

Hering- Breuer reflex

Back 11

- regulation via gaseous concentrations doesn't prevent overstrecthing of lungs
- stretch receptors in smooth m of the wall of bronchi and bronchioli transmit a signal to the respiratory center, terminating inspiration

Front 12

cough

Back 12

- receptors in larynx and bronchi
- irritation by dust, mucous, food particles, etc
- cause strong expiration

Front 13

sneeze

Back 13

- receptors in mucous membranes of the nose
- irritation by dust, mucous, food particles, etc
- cause strong expiration

Front 14

cough and sneeze reflex

Back 14

- start of reflex: glottis close and P in lungs increases
- sudden opening of the glottis results in an explosion-like onset of air flow
= air expired at a high velocity

Front 15

central receptors gen

Back 15

- medulla oblongata
- measure CO2

Front 16

peripheral receptors gen

Back 16

- aorta, carotid a
- measure O2, H+, CO2

Front 17

central receptors fx

Back 17

- measure PCO2 vis CSF pH
- CO2 diffuses easily from blood into CSF
- CSF pH mirrors acute changes in pCO2 because of low [CSF buffer]
- adaptation after 24- 48 hrs

Front 18

peripheral receptors fx

Back 18

- measure PO2, PCO2, pH
- glomus caroticum, glomera aortica
- single cell type: Type I, measures the 3 parameters

Front 19

function of Type I cells
(peripheral receptors)

Back 19

1. low pH
2. low [O2]
3. high CO2
- block K channels and opens Ca channels, resulting in a release of transmitter