Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BFCBP Respiratory Physiology > Respiratory Physiology VI > Flashcards

Respiratory Physiology VI Flashcards

1
Q

What effect does sectioning above the medulla have on ventilation?

A

Not a great effect - fairly normal ventilation is maintained.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What effect does sectioning below the medulla have on ventilation?

A

Ventilation ceases.

i.e. the medulla is the major rhythm generator.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What network of neurons generate the breathing rhythm? What sort of activity do these neutrons display?

A

The Pre-Botzinger complex.

They exhibit pacemaker activity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the Pre-Botzinger complex located?

A

Near the upper end of the medullary respiratory centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the neural events which give rise to inspiration and its cessation in terms of the group or groups of neurons involved.

(Note - four steps.)

A
  1. Rhythm generated by the Pre-Botzinger complex.
  2. This excites dorsal respiratory group neurons (inspiratory).
  3. These fire in bursts which leads to contraction of inspiratory muscles.
  4. Cessation of firing then results in passive expiration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the neural events which give rise to “active” expiration during hyperventilation?

(Note - three steps.)

A
  1. Increased firing of dorsal neurons excites a nearby group of neurons: ventral respiratory neurons.
  2. These neurons then fire leading to contraction of internal intercostals, abdominals etc. (muscles of active expiration).
  3. This results in forceful expiration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

During normal quiet breathing, do ventral neurons activate expiratory muscles?

A

No, only during exaggerated breathing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Neurons in which (specific) area of the brain can modify the breathing rhythm which is generated?

A

The pons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where is the “pneumotaxic centre (PC)”?

A

The pons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe how the rhythm of breathing is modified by the pons of the medulla.

(Two steps.)

A
  1. The pneumotaxic centre is stimulated when dorsal respiratory neurons fire.
  2. This inhibits inspiration.

Thus, stimulation of the pneumotaxic centre terminates inspiration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe the breathing rhythm without influence from the pneumotaxic centre (PC) and give the medical term for this.

A

Without the PC, breathing is prolonged inspiratory gasps with brief expiration.

This is called apneusis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe how the apneustic centre acts to modify breathing.

A
  1. Impulses from the apneustic centre excite the inspiratory area of the medulla.
  2. This results in prolonged inspiration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What conclusion can be drawn about where breathing rhythm is generated in the brain and which part of the brain can provide inputs to modify it?

A

The rhythm is generated in the medulla.

The rhythm can be modified by inputs from the pons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some stimuli which influence the respiratory centres?

A
  1. Higher brain centres.
  2. Stretch receptors in bronchi and bronchiole walls -Herin-Breur reflex, guards against hyperinflation.
  3. Juxtapulmonary (J) receptors stimulated by pulmonary congestion and pulmonary oedema.
  4. Joint receptors.
  5. Baroreceptors - ventilation increased when BP low.
  6. Central and peripheral chemoreceptors - chemical control of respiration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give four examples of involuntary modifications of breathing.

A
  1. Pulmonary stretch receptors (Hering-Breur reflex).
  2. Joint receptors reflex - during exercise.
  3. Stimulation of respiratory centre by temperature, adrenaline, or impulses from the cerebral cortex.
  4. Cough reflex.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When are pulmonary stretch receptors activated and what activity from these inhibits respiration?

A

Activated during inspiration.

Afferent discharge of these inhibits inspiration - the Hering-Breur reflex.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Do pulmonary stretch receptors switch off inspiration during the normal respiratory cycle?

A

No, it is unlikely as they are only activated at large (> 1L) tidal volumes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

When are pulmonary stretch receptors thought to be of importance in preventing lung hyperinflation?

(Two scenarios.)

A

In newborn babies.

During hard exercise.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do joint receptors modify breathing?

A

Impulses from moving limbs reflexly act to increase breathing.

This probably contributes to the increased ventilation during exercise.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

List five factors that may increase ventilation during exercise.

A
  1. Reflexes originating from body movement.
  2. Adrenaline release.
  3. Impulses from the cerebral cortex.
  4. Increase in body temperature.
  5. Later: accumulation of carbon dioxide and hydrogen ions generated by active muscles.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the main function of the cough reflex?

A

It acts as a vital part of the body defence mechanisms by helping to clear the airways of dust, dirt or excessive secretions.

22
Q

What activates the cough reflex?

A

Irritation of airways or tight airways (e.g. asthma).

23
Q

Where is the centre which controls the cough reflex?

A

The medulla.

24
Q

What are the four steps following afferent discharge of sensory nerves which bring about a cough?

A
  1. A short intake of breath is stimulated.
  2. The larynx is closed.
  3. The abdominal muscles contract to increase intra-alveolar pressure.
  4. The larynx opens and air is expelled from the lungs at high speed.
25
Q

What type of feedback system is chemical control of respiration an example of?

A

A negative feedback control system.

26
Q

What are the controlled variables in the chemical control of respiration and what sense changes in these?

A

The controlled variables are the blood gas tensions, especially carbon dioxide.

Chemoreceptors sense the values of these gas tensions.

27
Q

In which two locations can peripheral chemoreceptors be found?

A
  1. Aortic bodies.

2. Carotid bodies.

28
Q

What three things do peripheral chemoreceptors sense in the blood?

A
  1. Tension of oxygen.
  2. Tension of carbon dioxide.
  3. Concentration of hydrogen ions in the blood.
29
Q

Where are central chemoreceptors located?

A

Near the medulla of the brainstem.

30
Q

What do central chemoreceptors detect?

A

They detect changes in the hydrogen ion concentration of the cerebrospinal fluid (CSF).

31
Q

What happens to ventilation as the partial pressure of carbon dioxide increases?

A

It greatly increases as the system is very responsive to changes in this.

32
Q

What happens to ventilation as the arterial partial pressure of oxygen becomes progressively lowered in hypoxia? What about in very severe hypoxia?

A

The peripheral chemoreceptors become stimulated so ventilation greatly increases.

However, below a certain partial pressure of oxygen, neurons become depressed and so the ventilation begins to decrease again.

33
Q

What receptors becoming stimulated is hypoxic drive a result of?

A

Peripheral chemoreceptors.

34
Q

At what value of arterial partial pressure of oxygen do peripheral chemoreceptors become stimulated?

A

< 8.0 kPa.

35
Q

Is hypoxic drive important in normal respiration? In which two cases does it become important?

A

No, it is not important in normal respiration, however:

  1. It may be important patients with chronic carbon dioxide retention (e.g. patients with COPD).
  2. It is important at high altitudes.
36
Q

What causes hypoxia at high altitudes?

A

Decrease in partial pressure of inspired oxygen (PiO2).

37
Q

What is the acute response to hypoxia at high altitudes?

A

Hyperventilation and increased cardiac output.

38
Q

What are the symptoms of acute mountain sickness?

A

Headaches, fatigue, nausea, tachycardia, dizziness, sleep disturbance, exhaustion, shortness of breath, unconsciousness.

39
Q

What happens RBC production as a result of chronic high altitude hypoxia and what is the advantage of this?

A

It increases - polycythaemia.

This results in greater oxygen carrying capacity in the blood.

40
Q

What happens to the production of 2,3-BPG within RBCs as a result of chronic high altitude hypoxia and what is the advantage of this?

A

It increases.

This results in oxygen being offloaded more easily into tissues - remember, increased 2,3-BPG is part of the Bohr effect.

41
Q

What happens to the number of capillaries as a result of chronic high altitude hypoxia and what is the advantage of this?

A

They increase in number.

This results in blood diffusing more easily to where it is needed by tissues.

42
Q

What happens to the number of mitochondria as result of chronic high altitude hypoxia and what is the advantage of this?

A

They increase in number.

This results in more efficient use of oxygen.

43
Q

What do the kidneys do as a result of chronic high altitude hypoxia and what is the advantage of this?

A

They conserve acid.

This lowers arterial pH.

44
Q

What receptors being stimulated is the hydrogen ion drive of respiration a result of?

A

Peripheral chemoreceptors.

45
Q

Out of the following, which readily crosses the blood-brain barrier and which does not?

a) hydrogen ions and b) carbon dioxide.

A

a) Does not readily cross the blood brain barrier.

b) Readily crosses the blood brain barrier.

46
Q

What change in blood acid-base balance do the peripheral chemoreceptors play a key role in adjusting for?

A

Acidosis caused by the addition of non-carbonic acid hydrogen ions to the blood.

e.g. lactic acid during exercise or diabetic ketoacidosis.

47
Q

What does peripheral chemoreceptor stimulation by hydrogen ions cause?

A

Hyperventilation which increases the elimination of carbon dioxide from the body (as carbon dioxide can generate hydrogen ions so is not wanted if hydrogen ion concentration is excessively high).

48
Q

What effect does arterial carbon dioxide (or hydrogen ion concentration in brain CSF) have on:

a) the peripheral chemoreceptors, and
b) the central chemoreceptors?

A

a) Weak stimulation.

b) Strong stimulation - dominant control of ventilation.

49
Q

What effect does arterial partial pressure of oxygen have on:

a) the peripheral chemoreceptors, and
b) the central chemoreceptors?

A

a) Only becomes important if partial pressure of oxygen falls to < 8 kPa.
b) Severe hypoxia depresses the respiratory centre.

50
Q

What effect does arterial hydrogen ion concentration have on:

a) the peripheral chemoreceptors, and
b) the central chemoreceptors?

A

a) Stimulation - important in acid-base balance.

b) Hydrogen ions cannot cross the blood-brain barrier.

BFCBP Respiratory Physiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions