Physiological control of respiration Flashcards
involves the inward and outward movement of air
into the lungs
Respiration
The rate of respiration regulates the partial pressures of ___ and ___ in the blood
oxygen (PaO2)
carbon dioxide (PaCO2)
___ from the brain are responsible for rhythmic discharge
Nerve impulses
This rhythmic discharges from the brain are regulated by changes in arterial __
PaO2, PaCO2 and hydrogen ion (H+)
concentration
Respiration is controlled through ___
neuronal feedback loops
These feedback loops are comprised of the
control centre, sensors, and effectors, namely:
- Control centre:
- respiratory nuclei in the cerebral cortex and brainstem.
- Sensors:
- mechanoreceptors
- peripheral and central chemoreceptors.
- Effectors:
- muscles of respiration
The ___, ____, and ____ comprise the neural control of respiration
cerebral cortex, medulla and pons
responsible for
voluntary control of breathing
cerebral cortex
responsible for automatic breathing
medulla and pons
The nerve impulses arising from respiratory neurons in these areas regulate the activity of respiratory muscles, by activating motor neurons in the ___ and ___ spinal cord that eventually innervate respiratory muscles
cervical
thoracic
The physical changes in the lungs are then sensed by the ____ and central and peripheral ____ to further adjust the breathing
mechanoreceptors
chemoreceptors
The higher centre of the brain responsible for control of respiration is the ____
cerebral cortex
The ___ is responsible for initiating any voluntary muscular movement, including that responsible for respiration
primary motor cortex
Controlled exhalation is regulated from the ___ portion of the primary motor cortex
inferior
The ___ portion of the primary motor cortex is responsible for initiating the voluntary contraction and relaxation of the internal and external intercostal muscles
superior
Diaphragm control from the higher centre is also located within the ___ portion of the motor cortex
superior
The respiratory centre is comprised of four main anatomical areas, namely:
the dorsal respiratory group (DRG)
ventral respiratory group (VRG)
apneustic centre
pneumotaxic centre
area of brain responsible for the respiratory pattern generation and where coordination of various voluntary and involuntary demands on respiratory activity occurs.
medulla
The medullary respiratory centre is composed of two groups of neurons that are concentrated in two anatomical areas
inspiratory centre (dorsal respiratory group)
expiratory centre (ventral respiratory group)
The DRG is located next to the ___ near the
root of cranial nerve IX
nucleus tractus solitarius
the DRG has sensory afferents from peripheral
chemoreceptors via the ___ nerve and ___
nerve
glossopharyngeal
vagus
functions in both quiet or forced respiration and contains neurons that control lower motor neurons innervating the external intercostal muscles and the diaphragm
DRG
This group of neurons primarily control the timing of the respiratory cycle
DRG
Motor output is sent to the diaphragm from the DRG via the ___
phrenic nerve
a network of neurons located ventrally in the brain
stem extending from the spinal cord to the pons medulla junction
VRG
The VRG expiratory centre is primarily responsible
for ___
expiration
These neurons are primarily inactive during quiet
breathing because expiration is normally a passive process
VRG
The VRG comprises the following respiratory neurons:
- Caudal ventral respiratory group
- Rostral ventral respiratory group
- Pre-Bötzinger complex
- Bötzinger complex
responsible for the modification of rhythmic discharges from the medullary neurons
apneustic and the pneumotaxic centres
They regulate the depth and rate of respiration in response to sensory stimuli or input from other centres in the brain
apneustic and the pneumotaxic centres
The pneumotaxic centre located in the ____ interacts with the medullary respiratory centre (dorsal respiratory group) to reduce the depth of inspiration
upper pons
An increase in __ output increases the rate of respiration by shortening the duration of each inhalation
pneumotaxic
The apneustic centre is located in the __
lower part of the pons
During forced breathing, the apneustic centres respond to sensory input from the ___ nerves regarding the amount of lung inflation
vagus
There are two types of respiratory chemoreceptors, namely
peripheral, and
central chemoreceptors
are the main influencer of respiration.
Peripheral chemoreceptors
Peripheral chemoreceptors are located in the ____ and ___
carotid (at the bifurcation of the carotid artery) and aortic bodies (on the aortic arch
The afferent impulses from the carotid bodies are carried via the ___ nerve, whereas those from the aortic bodies are carried via the ___ nerve
glossopharyngeal
vagus
he only chemoreceptors in the body that respond to hypoxaemia
aortic and carotid bodies
stimulates both aortic and carotid bodies
High PaCO2
the ___ are only responsible for 20% of the body’s response to hypercapnia
peripheral
chemoreceptors
______ only stimulates the carotid
bodies.
Low pH
Low blood pressure leads to ____of the carotid
and aortic bodies, subsequently increasing their neuronal output
hypoperfusion
Central chemoreceptors are located in the ___, on the ventral surface, however, separate from the VRG
medulla
They detect chemical changes in the medulla
Central chemoreceptors
Central chemoreceptors are stimulated
by a drop in ___
cerebrospinal fluid (CSF) pH
CO2 then reacts with water, catalysed by ____ enzyme to form carbonic acid (H2CO3)
carbonic anhydrase (CA)
stimulate the respiratory centre through the
lung stretch receptors and muscle spindles
Mechanoreceptors
The lung stretch receptors are located in the ____ and they are stimulated by overinflation of the lung
bronchial smooth muscle
occurs when the steady lung inflation results in an increase in the duration of expiration
Hering–Breuer inflation reflex
a decrease in the duration of expiration as a result of marked lung deflation is called the
Hering–Breuer deflation reflex
During exercise there is a change in respiration and this change
is initiated by ___ activity
muscle spindle
These receptors are located in the airway epithelium
Irritant receptors
Irritant receptors cause ___ and stimulate ___as a protective mechanism in response to inhalation of noxious gases
bronchoconstriction
ventilation
Chemicals such as ___ also stimulate Irritant receptors, thereby, activating rapidly adapting receptors in the trachea causing coughing, bronchoconstriction and secretion of mucus
histamine
non-myelinated C-fibres in the alveolar walls and located in close proximity to pulmonary vessels
Juxtacapillary receptors (J-receptors)
They are activated by hyperinflation of the lung, dyspnoea, bradycardia and hypotension
Juxtacapillary receptors (J-receptors)
Intravenous or intracardiac administration of ___ also leads to the activation of J receptors, producing a reflex response termed pulmonary chemoreflex
capsaicin
produced by receptors in the heart
Bezold–Jarisch reflex
Ventilation is stimulated by activation of
pain recepors
Ventilation is stimulated by an increase in ___
core temperature
The fact that pain and emotional stimuli results in hyperventilation, suggests that afferents from the ___ and ___ send signals to the respiratory neurons in the brainstem
limbic system
hypothalamus
