Diving Response II

Question 1

• The diving response serves the purpose of….
• Under conditions where…. and…. the diving response is initiated
• The human diving response is highly variable and can be modified by what two factors
• Elite breath-hold divers have developed certain adaptions to repeated apnea training, such as: greater tolerance to…and more pronounced…

Answer 1

• The diving response serves the purpose of preserving life.
• Under conditions where respiration ceases and the face becomes submerged, the diving response is initiated (colder the water the stronger the response)
• The human diving response is highly variable and can be modified by physiological as well as emotional factors
• greater tolerance to hypoxia and hypercapnia, and a more pronounced diving response

Question 2

Apnea time depends on:
1. Physiological response to hyp_____ and hyp_____

2. Intensity of _____ (larger what and reduced what)
3. Capacities for what two things (How is this achieved)
4. Psychological tolerability to hyp____ and hyp_____

Answer 2

1. Physiological response to hypercapnia and hypoxia
2. Intensity of metabolism (larger activity of the anaerobic and reduced aerobic metabolism)
3. Capacities for O2 and CO2 (TLC, training, hyperventilation)
4. Psychological tolerability to hypercapnia and hypoxia

Question 3

Physiological Challenges in extreme free dive and apnea

Physiological/psychological response to..
– PaO2 (20-30 mmHg), SaO2 (~50%), PaCO2 (55+ mmHg), what are these values normally

Extreme ambient HP
– ________ at descent and ascent
– Pulmonary _______ and alveolar ______

Increased gas uptake and nitrogen supersaturation
– N2 ______
– _________ sickness

Answer 3

Physiological/psychological response to hypoxia and hypercapnia
– PaO2 (20-30 mmHg), SaO2 (~50%), PaCO2 (55+ mmHg), O2 usually 100hhmg and 98-100% and CO2 usually 40mmhg

Extreme ambient hydrostatic pressure
– Barotrauma at descent and ascent (air bubbles forming in blood)
– Pulmonary edema and alveolar hemorrhage (from barotrauma)

Increased gas uptake and nitrogen supersaturation
– N2 narcosis
– Decompression sickness (Deco stops)

Question 4

Metabolic Challenges
* Peripheral vasoconstriction during breath hold is primarily at the level of (2)

• _____ blood flow is maintained
• Blood is redirected to the ______

Answer 4

• Peripheral vasoconstriction during breath hold is primarily at the level of the skin and skeletal muscle
• Liver blood flow is maintained
• Blood is redirected to the brain

Question 5

Psychological Tolerance
* The p______ and p______ components of breath holding are intertwined

• Need to stay ______ in order to reduce sympathetic nervous system elevations
• Have self-awareness of the….. your body and suppress the…..
• During an elite athlete 6 minute breath hold (dry), what apnoea/chest pleth start why is it flat? what happens what involuntary breathing movements? what about end when we finally breath

Answer 5

• The physical and psychological components of breath holding are intertwined
• Need to stay calm in order to reduce sympathetic nervous system elevations (HR rise to anxiety)
• Have self-awareness of the physiological limits of your body and suppress the desire to breathe (Co2 levels rise and trigger breathing reflex)
• apnoea is flat because Co2 hasn’t built up yet (no triggered breathing response, easy phase). Involuntary breathing movements begin at start of hard phase as co2 is built up and involuntary contractions of chest. Finally apnoea end when we breath because accessory muscles kick in (breath)

Question 6

Mechanisms
1. Changes of CR

2. Peripheral ______ and redistribution of blood to….
3. ______ pressure alterations
4. Reduction of….
5. Contraction of the ____

Answer 6

1. Changes of cardiac rhythm (bradycardia)
2. Peripheral vasoconstriction and redistribution of blood to the central blood reservoir
3. Arterial pressure alterations
4. Reduction of cardiac output
5. Contraction of the spleen

Question 7

1. Changes of cardiac rhythm (bradycardia)

• Initial anticipatory _______ (stimulation of the lung ______)

Increased parasympathetic input to SA node
– Immersion of the face in the cold water (stimulation of what nerve)
– Enlargement of ______ inflow and distention of _____ cavities

• Arrhythmias, what kind

Answer 7

• Initial anticipatory tachycardia (stimulation of the lung mechanoreceptors; hyperventilation; excitement; stress)

Increased parasympathetic input to SA node
– Immersion of the face in the cold water (stimulation of trigeminal nerve), more parts of face you stimulate the bigger the response
– Enlargement of venous inflow and distention of heart cavities (pre load increase, better flow)

• Arrhythmias (bradyarrhythmia and extra beats), due breath hold for long time

Question 8

2. Peripheral vasoconstriction and redistribution of blood to the central blood reservoir

• Increased sympathetic outflow to periphery – reduced blood flow to…..
• Anaerobic metabolism on the ______, what increases
• Blood centralization to what two places
• _____% increase of cerebral flow through what atery

Answer 8

• Increased sympathetic outflow to periphery – reduced blood flow to the peripheral tissues and skin
• Anaerobic metabolism on the periphery (lactate increases)
• Blood centralization to the brain and heart
• 100% increase of cerebral flow through middle cerebral artery (MCA)

Question 9

4. Reduction of cardiac output

• The haemodynamics at the onset of a maximal breath hold after a full inspiration can largely be compared with what
• High lung volumes throughout reduce what two things

Answer 9

• The haemodynamics at the onset of a maximal breath hold after a full inspiration can largely be compared with the second phase of a Valsalva manoeuvre
• High lung volumes throughout reduce ventricular filling and therefore cardiac output

Question 10

3. Arterial pressure alterations (bp climb and hr fall through breathold)

• Peripheral vasoconstriction increases TPR and can increase ____
• Involuntary breathing contractions can also cause swings….

Answer 10

• Peripheral vasoconstriction increases total peripheral resistance and can increase BP
• Involuntary breathing contractions can also cause swings in BP

Question 11

5. Contraction of the spleen

• Significant reservoir of blood to many ….
• Exercise and diving cause….
• Increased _______ activity (α1-stimulation)

Answer 11

• Significant reservoir of blood to many land and water mammals (RBC, WBC, platelets)
• Exercise and diving cause the contraction of the spleen
• Increased adrenergic activity (α1-stimulation)