Control of breathing Flashcards

1
Q

What controls respiration?

A

-autonomic control
-unconcious
-negative feedback system to maintain blood gases and acid base balance within normal ranges for optimal cellular function
-can be manually overidden
-odines curse- congenital central hypoventilation syndrome

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2
Q

Whats involved with the voluntary regulation- manual override of breathing?

A

-coritcal influences:
-breath holding, coughing, speaking, laughing

-limbic influences:
-fear,anger, pain, anxiety

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3
Q

Describe the feedback control of respiration

A

sensors-chemoreceptors, lungs and others

-central controller- pons, medulla, other brain parts

-effectors- respiratory muscles

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4
Q

What is the general role of the respiratory centre?

A

-central controller
-located in several regions in medulla and pons of brainstem
-generates respiratory rythm
-controls rate, depth and resp pattern

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5
Q

Where is the respiratory centre located?

A

-medullary centre- below 4th ventricle in medulla

-apneustic area- lower pons

-Pneumotaxic area- upper pons

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6
Q

Function of the medullary centre

A

-setting of basic respiratory rhythm
-dorsal respiratory group-inspiration
-ventral respiratory group-inspiration and expiration ( dormant during quiet breathing)

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7
Q

What is the function of the apneustic area?

A

excitatory effect on inspiratory area of the medulla and causes prolonged inspiration

-stimulates dorsal resp group and increases resp

-gets feedback from vagal nerves and other resp centres

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8
Q

What is the function of the pneumotaxic area?

A

-controls the transition of inspiration to expiration by inhibiting inspiration
-regulate inspiratory volume and rate
-element of fine tuning

-signals to inspiratory area and controls the switch off point for the insp ramp- controls filling phase of lung cycle

-strong signal from here reduces the ramp time to 0.5s and also reduces the duration of expiration, increasing RR

-a weak signal will increase duration of both insp and exp and reduces RR

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9
Q

Whats the function of the dorsal respiratory group?

A

-control of respiration, generates the basic rythum of respiration

located- dorsal medulla, close to sensory termination of both vagal and glossopharyngeal nerves which transmit sensory signals into the resp centre

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10
Q

What is the inspiratory ramp signal?

A

-nervous signal to inspiratory muscles is a steadily increasing signal, increasing over a period of 2 secs

-results in inspiratory muscle contraction and air enters the lungs

-singal stops for 3 secs, stops excitation of inspiratory muscles

-lungs passively recoil during expiration
-cycle repeats

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11
Q

Describe the ventral respiratory groups 4 nuclei and their functions

A

1- botzinger complex- controls expiration
2-pre-botzinger complex- sets respiration pace
3-nucleus ambiguous-inspiratory neurosn
4-nucleus retro ambiguous- has inspiratory and expiratory neurons

-particulary active during forced respiration- excersise

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12
Q

What are the effectors involved with breathing control?

A

-coordinated by the central controller
-diaphragm
-intercostal muscles
-abdominal muscles
-accessory muscles

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13
Q

Name some respiratory receptors

A

chemoreceptors- central and peripheral

lung receptors- J receptors, irritant receptors , stretch receptors

-receptors in muscles and joints

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14
Q

Where are central chemoreceptors located?

A

ventral surface of medulla in brainstem

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15
Q

What is the function of central chemoreceptors?

A

-Respond to H+ conc in CSF
-raised H+= increased ventilation
-Lowered H+ = decreased ventilation

CO2 can diffuse across the blood brain barrier- an increase in co2 in CSF will increase the H+ conc and stimulate the central chemoreceptors

-not sensitive to changes in PaO2, responsible for 80% of the response to CO2 , relatively slow response

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16
Q

Where are peripheral chemoreceptors located?

A

-cartoid bodies at bifurcation of common carotoid arteries

-aortic bodies above and below aortic arch

-carotid bodies most important

17
Q

What is the function of peripheral chemoreceptors?

A

-respond to changes in blood PCO2, H+ and PO2

-20% of ventilatory response to CO2, much more rapid response than central chemoreceptors

18
Q

Where are stretch receptors located?

A

smooth muscle of bronchial walls

19
Q

What is the function of stretch receptors?

A

stimulation leads to
-shortening of inspiration
-shallow inspiration
-delay before next breath

-Hering-breuer inspiratory reflex

20
Q

What is the Hering- Breuer reflex?

A

-volume reflex where lung inflation inhibits inspiratory muscle activity and prevents overinflation of lungs

-when airways are stretched, receptors stimulated, sends impulses to dorsal respiratory group

-switches of inspiratory ramp, stops inspiration, results in expiration

-reflex is weak in normal breathing, important when tidal volume increases- excersise

21
Q

Where are J receptors located?

A

on alveolar and bronchial walls close to cappilaries

22
Q

Wjhat are J receptors also known as?

A

juxtaposition receptors or c-fibres receptors

23
Q

What is the function of J receptors?

A

-stimulated by pulmonary oedema, microembolisms, inflammatory mediators

-activation results in apnoea, decreased HR, reduced BP and larynx constriction

24
Q

Where are irritant receptors located?

A

throughour airway in between epithelial cells

25
Q

What is the function of irritant receptors?

A

-stimulated by irritant gases,smoke,dust,airway deformation and inflammation

-results in bronchial and laryngeal constriction, sneezing and coughing

-responsible for deep sighs taken every 5-20 mins during normal breathing

26
Q

Where are proprioreceptors located?

A

golgi tendon organs,muscle spindles and joints

27
Q

What is the function of proprioreceptors?

A

-stimulated by invreased load and shortening respiratory muscles

-help achieve optimal tidal volume and frequency

28
Q

What is the function of pain receptors and arterial baroreceptors?

A

pain- brief apnoea followed by periods of hyperventilation

Arterial baroreceptors- simulation from increased BP, results in reduced respiratory rate and depth