24 Flashcards
where’s the respiratory control cnetre
pon and medulla
four inputs to respiratory centre
- voluntary control via cerebum
- central chemoreceptor
- peripheral chemoreceptr so carotid and aortic
- mechanoreceptor in lung
- muscle proprioreceptos
what does the respiratory control centre innervate
spinal motor neurones
what do spinal motor neurones innervate
respiratory muscles
where does CSF get formed
choroid plexus
how is CO2 increase sensed
CO2 diffuses to CSF where it becomes carbonic acid bc interacts w water. csf has CA so carbonic acid becomes H plus and bicarbonate. Hplus is sensed by central chemoreceptors in the ventral surface of medulla
where are central chemoreceptors found
ventral surface of medulla
if csf is acidic would you have more or less ventilation
more because you want to expel CO2
what do chemoreceptors send signals to
respiratory neurones
normal pH of CSF
7.32
why does CSF have much lower buffering capacity than blood
bc it has no proteins.
what types of receptors exist in the lungs
- stretch receptors
- irritants
- J receptors
where are stretch rectors found
bronchioles and small bronchi
function of stretch receptors
inhibit inspiration when lungs are fully inflated. send AP to vagus nerve to respiratory centre in pons and medulla to inhibit phrenic innervation of diaphragm
whats the Hering Breuer inflation reflex
its the mechanism by which when your lungs are fully inflated they won’t inflate more because the stretch receptors in the lungs send a message to the vagus nerve to prevent phrenic innervation of diaphragm.
where are irritant receptors found
trachea and primary bronchi
function of irritant receptors
detect presence of foreign object, activate cough reflexes
what type of receptors are J receptors
chemoreceptors.
function of j receptors
respond to Edema Emboli…
detect fluid in alveoli
send signal via vagus to increase ventilation and respiration
whats the shape of the curve of ventilation depending on partial pressure of CO2
linear
what increases sensitivity to CO2
hypoxia
at what partial pressure of O2 will hypoxia be taken into consideration by respiratory centres
60 mmHg sinon it reamin unchanged
what hypercapnia
increase in CO2 partial pressure
where are sensors for hypoxia
in peripheral chemoreceptors
carotid body on top of bifurcation
and below and above aortic arch
what structure contains the most heavily vascularised tissue in the human body
carotid body
what cells make up the carotid body
type I glomus cells (chief cells) like chromatin cells, produce neurotransmitter that stimulate glossopharyngeal nerves that project to respiratory centres. type II (sustentacular cells): normal CT supportive like glia
how does SNS affect carotid body
increases sensitivity to hypoxia
how do type 1 glomus cells detect hypoxia
hypoxia leads to closure of K channels.so Na and Ca channels open causing the realise of NT like acetylcholine which act on receptors on afferent nerve fibres near glomus and cause AP to go to respiratory centres
what receptor is the main contributor to breathing urge
central chemoreceptor
pulmonary receptors all input to
NST which projects to dorsal respiratory area. (medullary reticular formation)
what neurones become active during forced expiration
neurones in the ventral respiratory area which go to the reticulospinal tract
which side of the respiratory area is involved with inspiration?
dorsal
which side of the respiratory area is involved with expiration?
ventral
what regulates medullary respiratory region
the apneustic centre
pneumotaxic centre
what does the apneustic centre cause
prolonged inspiration
voluntary breath holding is achieved by what
apneustic centre
what does the pneumotaxic centre cause
inhibits apneustic centres
regulates breathing for singing
but cannot completely override medullar centre so can’t hold breath for too long.
