Diving Response 2

Question 1

The diving response is variable and is modified by … and … factors
* Elite breath-hold divers have greater tolerance to hypoxia and …, and a … diving response

Apnea time depends on:
1. Physiological response to … and …
2. Intensity of … (larger activity of the … and reduced … metabolism)
3. Capacities for … and … (TLC, training, hyperventilation)
4. Psychological … to hypercapnia and hypoxia

WHERE DOES SYMP AND PARA ACT IN BODY

Answer 1

The diving response is variable and is modified by physiological and emotional factors
* Elite breath-hold divers have greater tolerance to hypoxia and hypercapnia, and a more pronounced diving response

Apnea time depends on:
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

PARA ON TRUNK, NOT PERIPHERY, SYMP EVERYWHERE

Question 2

Physiological Challenges during diving
What should PaO2, SaO2, and PaCO2 be at rest

During hypoxia and hypercapnia
– PaO2 (20-30 mmHg), SaO2 (~50%), PaCO2 (55+ mmHg) SUPER DIFFERENT THAN NORMAL

Extreme ambient … pressure
– …trauma at descent and ascent
– Pulmonary … and alveolar …

Increased gas uptake and nitrogen supersaturation
– … narcosis
– … sickness (…)

GRAPH!!!!!!!! what happens to O2 and CO2

Answer 2

PaO2 = 100, SaO2 = 92-100%, and PaCO2 =40

Physiological/psychological response to hypoxia and hypercapnia
– PaO2 (20-30 mmHg), SaO2 (~50%), PaCO2 (55+ mmHg)

Extreme ambient hydrostatic pressure
– Barotrauma at descent and ascent
– Pulmonary edema and alveolar hemorrhage

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

Question 3

Metabolic Challenges During Diving
* Peripheral … is at the level of the skin and skeletal muscle
* Liver blood flow is …
* Blood is redirected to the …

Psychological Tolerance
* Physical and psychological components are intertwined
* Stay calm to reduce … nervous system elevations
* Self-awareness of the physiological limits of your body and suppress the …

explain what is happening in this graph

Answer 3

Metabolic Challenges During Diving
* Peripheral vasoconstriction is at the level of the skin and skeletal muscle
* Liver blood flow is maintained
* Blood is redirected to the brain

Psychological Tolerance
* Physical and psychological components are intertwined
* Stay calm to reduce sympathetic nervous system elevations
* Self-awareness of the physiological limits of your body and suppress the desire to breathe

when you are holding your breath for a long long time, the diaphragm starts to move because the urge to breathe is that severe

Question 4

Mechanisms of the Diving Response

1. Changes of cardiac rhythm (…cardia)
   * Initial anticipatory… (Lung mechanoreceptors; hyperventilation; …; …)
   * Increased … input to … node
   – Stimulation of … nerve
   – … of venous inflow and … of heart cavities - …
   can lead to …
   WHEN ONE PART OF THE FACE OR THE WHOLE FACE IS SUMERGED? -
2. Peripheral … and redistribution of blood to the …
   * Increased … tone to the periphery – … blood flow to the peripheral tissues and skin
   * … metabolism on the periphery (lactate increases)
   * Blood centralization to the …
   * …% increase of cerebral flow through middle cerebral artery (MCA)
   … BP, … HR, … FOREARM FLOW

Answer 4

Mechanisms of the Diving Response

1. Changes of cardiac rhythm (bradycardia)
   * Initial anticipatory tachycardia (Lung mechanoreceptors; hyperventilation; excitement; stress)
   * Increased parasympathetic input to SA node
   – Stimulation of trigeminal nerve
   – Enlargement of venous inflow and distention of heart cavities - PRELOAD
   can lead to arrythmias
   WHEN ONE PART OF THE FACE OR THE WHOLE FACE IS SUMERGED? - when the whole face is submerged the diving response affect is greater
2. Peripheral vasoconstriction and redistribution of blood to the central blood reservoir
   * Increased sympathetic tone to the 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)
   HIGH BP, LOW HR, LOW FOREARM FLOW

Question 5

Mechanisms of the Diving Response

3. Arterial pressure alterations
   - Peripheral vasoconstriction increases total peripheral … and can increase …
   - Involuntary breathing contractions can also cause swings in BP - …
4. Reduction of cardiac output
   Onset of a maximal breath hold after a full inspiration can be compared with the … phase of a Valsalva manoeuvre
   * High lung volumes throughout reduce … filling and therefore … output
5. Contraction of the …
   * A significant reservoir of … to mammals (RBC, WBC, platelets)
   * Exercise and diving cause the contraction of the …
   * Increased … activity (α1-stimulation)

Answer 5

Mechanisms of the Diving Response

3. Arterial pressure alterations
   - Peripheral vasoconstriction increases total peripheral resistance and can increase BP
   - Involuntary breathing contractions can also cause swings in BP - increasing
4. Reduction of cardiac output
   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 - Low BP high HR
   * High lung volumes throughout reduce ventricular filling and therefore cardiac output
5. Contraction of the spleen
   * A 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)

Question 6

🧊 Cold Water Stimulation
Whole body cold receptors → trigger vasoconstriction and blood redistribution
Facial cold receptors → stimulate the trigeminal nerve → activates medullary cardiovascular center

🫁 Breath-Holding (Apnea)
Voluntary breath hold → initiated by choice
Involuntary breath hold → triggered by water immersion or reflexes
Both lead to:
Closure of upper airways
Apnea → no breathing
CO₂ retention and hypoxia (low oxygen)

🧠 Brain and Consciousness
Hypoxia → reduces oxygen delivery to brain
CO₂ retention → affects cerebral vascular tone
Reduced cerebral blood flow → risk of loss of consciousness
Loss of consciousness → increases drowning risk

🫀 Cardiovascular Responses
Trigeminal nerve → activates medullary cardiovascular center
Vagal nerve stimulation → slows heart rate (bradycardia)
β-adrenergic innervation → affects heart rate and cardiac output
α-adrenergic innervation → increases vasomotor tone in muscles, viscera, skin
Blood pressure rises → helps maintain perfusion to vital organs

🩸 Blood Redistribution and Storage
Mechanical immersion effect → blood shifts to chest
Increased cardiac diastolic volume
Spleen contraction → releases red blood cells → increases hematocrit
Blood O₂ and CO₂ stores increase → supports breath-hold endurance

🧬 Metabolic Adjustments
Anaerobic metabolism kicks in due to low oxygen
O₂ delivery and CO₂ removal prioritized for brain and heart

🔁 Feedback Loops
Chemoreceptor activity monitors CO₂ and O₂ levels
Signals sent to respiratory and cardiovascular centers to adjust responses

Question 7

🧘‍♂️ 1. Apnea Preparation
Relaxation & Mental Excitation: Helps control heart rate and oxygen consumption.
Diet: Impacts metabolism and CO₂ sensitivity.
Ventilation (breathing techniques): Affects oxygen levels and CO₂ tolerance.

Physiological Effects:
Muscle Tonus: Relaxed muscles use less oxygen.
Metabolism: Lower metabolic rate conserves oxygen.
O₂ Consumption & CO₂ Sensitivity: Determines how long a diver can resist the urge to breathe.
Circulating O₂: More oxygen in the blood means longer breath-hold capacity.
Preparatory Apneas: Practice breath-holds to condition the body.
Heart Rate (HR): Lower HR reduces oxygen use.

🏋️‍♂️ 2. Training
Training enhances both oxygen storage and oxygen economy.
🫁 VO₂ Storage (How much oxygen the body can hold)
Glossopharyngeal Insufflation: A technique to increase lung volume.
Lung Volume (↑TVC, RV): Bigger lungs = more oxygen.
Arterial O₂ & Hematocrit: More red blood cells = better oxygen transport.
Intrathoracic Pressure & Inspiration at TLC: Maximizes lung inflation.

⚙️ VO₂ Economy / CO₂ Minimum (How efficiently oxygen is used)
VO₂ Diffusion Space: Optimizes oxygen transfer from lungs to blood.
Sympathetic & Parasympathetic Nerve Activity: Controls blood flow and heart rate.
Peripheral Vasoconstriction: Redirects blood to vital organs.
Arterial Compliance: Flexible arteries help maintain blood flow.
O₂ & CO₂ Stores: More stored gases = longer breath-hold.
IBM: Likely refers to inspiratory muscle training or biomechanics.

⏳ 3. Apnea Duration
The final section explains what determines how long a diver can hold their breath.
Key Factors:
Urge to Breathe: Driven by rising CO₂ and falling O₂.
Motivation: Mental toughness and goal orientation can push limits.

🧠 Summary
Elite apnea performance is a complex interplay of:

Mental preparation
Physiological conditioning
Strategic training
Psychological resilience