true or false?

breathing is controlled automatically but can be voluntarily suspended or altered for short periods of time

this is true.

Automatic breathing can remain in 'brain dead' individuals who have lost brain cortical function

Ondine's curse

named after the myth of Ondine who cursed her unfaithful lover so that if he fell asleep he would forget to breathe, eventually he fell alseep from sheer exhaustion and his breathing stopped!

it is a respiratory disorder. It is fatal if left untreated.

Failure of autonomic breathing leads to >CO2 and <O2 in the blood.

this disorder can also result from spinal or brain trauma. person's affected suffer from respiratory arrest during sleep but apnea can also occur when awake.

mutation in PHOX2B gene on Chromosome 4

this gene codes for a transcription factor needed for development of neuronal pathways involved in autonomic control of breathing

motor cortex

which part of the brain participates in breathing modulations associated with postural changes?

true or false?

Levels of CO2 regulate breathing more than levels of O2?

True.

Both the rate and depth of breathing are regulated so that PCO2 in arterial blood is kept close to 40mm Hg

this can be overridden when arterial oxygen tension drops below 60 mm Hg. This is only likely in high altitudes or lung disorders

respiratory rate x tidal voume = MRV

MRV = 5 litres per minute but can raise to 130 litres/minute

60 mm Hg. This is dangerous!

the normal resting level of arterial Po2 is 100 mm Hg

the normal resting level of arterial Pco2 is 40 mm Hg

if someone had Pco2 of >90mm Hg what would this result in?

if someone had pCO2 of >180 mm Hg what would this result in?

pCO2> 90 mm Hg = coma

pCO2> 180 mm Hg = death

which controller initiates each breath? where is it located?

which sensors report back to the central controller?

a central respiratory controller initiates each breath

it is located in the brainstem (medulla oblongata) at the base of the brain.

proprioceptors

these are found in lungs and in respiratory muscles. they cause the inhibition of inspiration and promotion of expiration upon lung inflation

Central Chemoreceptors - responsive to arterial pCO2 by monitoring acidity of the cerebrospinal fluid (CSF) that bathes the brain and spinal cord

Peripheral Chemoreceptors - responsive to arterial pCO2, pO2 and H+ concentration

where are the central chemoreceptors located?

how are medullary chemoreceptors stimulated?

on the ventral surface of medulla oblongata in the brain stem.

these chemosensitive cells are bathed in CSF that has an equilibrium with arterial pCO2. CSF CO2 combines with water to form carbonic acid which dissociates into H+ ions and bicarbonate.

The CSF H+ ions diffuse into the tissue to stimulate medullary chemoreceptors

in the carotid bodies of carotid arteries. These branch from the aorta

also located in the aortic bodies in the aorta itself.

the Pons

extra: the medulla has the primary centres responsible for generation of respiratory rhythm.

these receptors respond to mechanical or chemical irritation and elicit complex reflexes such as sneezes and coughs

they are located throughout airways and lungs

baroreceptors located in the aorta and carotid arteries measure mean arterial pressure.