4-21 pt 1

What do chemoreceptors detect?

changes in H+, PCO2, PO2

what are the types of chemoreceptors?

peripheral and central

What do central chemoreceptors respond to?

blood PCO2 in CSF

how does carbonic anhydrase form carbonic acid?

CO2 and H2O

Where are central chemoreceptors located?

medulla

What do peripheral chemoreceptors respond to?

H+ or respiratory gas changes in the blood

how do peripherical chemoreceptors respond to H+?

independently of PCO2

what nerve do carotid chemoreceptors use?

glossopharynegeal

What nerve do the aortic chemoreceptors use?

vagus nerve

Where are peripheral chemoreceptors located?

carotid and aortic bodies

What are irritant receptors?

stimulated by particle matter

what are the types of irritant receptors?

sneeze
cough

what is action of irritant receptors?

exagg intake of breath followed by larynx closure
contract ab muscles
abrupt opening of vocal cords and explosive blast of ait

What are baroreceptors?

located in pleura and bronchi

respond to stretch

what is action of proprioceptors?

signal to respiratory center to INCREASE DEPTH

when do barorecptors send signals to respiratory center?

when overstretched

what is the inhalation relfex?

shuts off inspiration and protects against overinflation

What are proprioceptors?

muscles and joints are stimulated by body movements

UNCONSCIOUS

when does inspiration begin?

VRG inspiratory neurons fire spontaneously

In quiet inspiration where are the signals sent from the VRG?

nerve pathways that excite skeletal muscle

how long is inspiration?

2 seconds

When does quiet expiration occur?

when VRG is inhibited

how long does expiration last?

3 seconds

when do diaphragm and intercoastals contract?

inspiration

when do diaphragm and intercoastals relax?

expiration

what is normal respiratory rate?

12-15 breaths/minute

what is respiratory rate for quiet breathing?

eupnea

what is role of pontine respiratory center?

creates smooth transitions btw inspiration and expiration

what is apnea?

absence of breathing

is apnea voluntary or involuntary?

both

what is sleep apnea?

temporary cessation of breathing during sleep

how do chemoreceptors alter breathing?

send signals to DRG which send to VRG

what does the VRG trigger?

changes in rhythm and force of breathing

what causes a change in rate of breathing?

altering the amount of time spent in both inspiration and expiration

what causes a change in depth of breathing?

stimulation of accessory muscles, which results in greater thoracic volume changes

when does the ventilation of rate and depth increase?

central-detect increase of H in CSF
peripheral-detect increase of blood H or CO2

when does the ventilation of rate and depth decrease?

detect decreases in H or PCO2

how does PO2 levels influence breathing rate?

chemoreceptors more sensitive to changes in blood PCO2

what is the most important stimulus affecting breathing rate and depth?

blood PCO2

what does raising blood PCO2 by 5 mm Hg cause?

2X breathing rate

what is substance has sensitive chemoreceptors?

blood PCO2

what influences sensitive chemoreceptors in blood PCO2?

CO2 fluctuations

how is carbonic acid formed?

CO2 + water

why does carbonic acid change pH?

no buffers, initiates reflexes

what is substance has chemoreceptors that are NOT sensitive?

blood PO2

what changes in blood are not independent means of regulating breathing?

PO2

when are chemoreceptors stimulated independently of PCO2?

arterial oxygen must go from 95 to 60 mm Hg to have major effect

what happens when PO2 levels drop?

chemoreceptors more sensitive to blood PCO2

what causes a greater stimulation of chemoreceptors?

decreased PO2
increased PCO2
production of H+

how does hypothalamus affect breathing rate?

increases if body is warm

how does the limbic system affect breathing rate?

response to emotions and emotional memories

how does the frontal lobe of the cerebral cortex affect breathing rate?

voluntary changes in breathing patterns

-walking, talking, singing, breath holding, valsalva maneuver

what does the cerebral cortex bypass?

respiratory center to stimulate lower motor neurons directly

what does the anatomic structures of the respiratory system consist of?

smooth muscle
glands

what are the smooth muscles and glands controlled by?

autonomic brainstem nuclei

what are the breathing muscles of the respiratory system?

skeletal muscles

what are the breathing muscles controlled by?

somatic nervous system, autonomic nuclei, cerebral cortex

what controls of breathing are there?

reflexive-ANS
conscious-somatic nervous system

what is airflow?

amount of air moving in and out of lungs with each breath

what is airflow dependent on?

pressure gradient
resistance

what is equation for airflow?

F\=P/R

what is the pressure gradient?

atmo pressure-intra pul pressure

how is pressure gradient changed?

altering volume in thoracic cavity

-if more muscles used\=more change

how much air can enter with small volume changes of quiet respiration?

500 mL

what determines resistance?

elasticity of chest wall and lungs
bronchiole diameter
collapse of alveoli

how does elasticity affect resistance?

less elastic\=more resistance

what happens to elasticity with age?

replacement of elastic tissue with scar tissue (pulomary fibrosis)

what is pulmonary fibrosis?

scarred and damaged lung tissue

how does bronchiole diameter affect resistance?

smaller lumen-more resistance

how does bronchodilation effect resistance?

decreases

how does bronchoconstriction effect resistance?

increases

why does bronchiole diamter influence resistance?

friction the air experiences as travels through the passageway

what part of ANS causes bronchiodilation?

sympth

what part of ANS causes bronchioconstriction?

parasympth

how does collapsed alveoli impact resistance?

increases

when do alveoli collapse?

type 2 cells dont produce surfactant

what is importance of surfactant?

reduces surface tension in the alveoli

what part of breathing do alveoli collapse in?

inhalation/exhalation

exhalation

what is respiratory distress syndrome?

The absence of lung surfactant in premature infants

what is compliance?

Ease with which the lungs and thoracic wall can be expanded

what is compliance determined by?

alveolar surface tension and the elastic recoil of the lung and chest wall

what is relationship between lung expansion and compliance?

greater lung expansion\=greater compliance

what conditions increase resistance?

decrease bronchiole lumen-constriction
decrease in compliance

what do we need if have an increase in compliance?

more forceful inspirations

what is pulmonary ventilation?

movement of air into and out of the lungs

air btw atm and alveoli in 1 min

what is tidal volume?

amount of air per breath

QUEIT BREATHINGwhat

what is respiration rate?

number of breaths per minute

how is pulmonary ventilation calculated?

tidal volume x respiratory rate

what is normal tidal volume?

500 mL
.5 L

what is anatomic dead space?

volume of conducting airways

no exchange of gases

what is value of anatomic dead space?

150 mL

what is alveolar ventilation?

the amount of air that reaches the alveoli and is available for gas exchange per minute

How is alveolar ventilation calculated?

(tidal volume - anatomic dead space) x respiratory rate

what maximized alveolar ventilation?

deep breathing

what is physiological dead space?

anatomical dead space + alveolar dead space

in a heathy individual what is relationship between physiologic and anatomic dead space?

equal

why is dead space values equal in heathy ind?

loss of alveoli is minimal

what measures respiratory volume?

spirometer

What is inspiratory reserve volume? (IRV)

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation

what is IRV a measure of?

lung compliance