IB SEHS SUMMARY FCS

its corny but it works!

Central & Peripheral Nervous System

Trick: "Central = Control" → brain & spinal cord

"Peripheral = Pass it on!" → nerves that send messages to/from the CNS

Motor Unit

One boss neuron, many muscle minions

Sliding Filament Theory

🦴 Use: "SAC-SAC-ACT-MYO-CROSS-PULL"

➡ Sarcomere
➡ Actin
➡ Myosin
➡ Cross-bridge
➡ Power stroke = contraction➡ Relaxation = detachment

Types of Synovial Joints

• Shoulder – Ball & Socket

• Elbow – Hinge

• Wrist – Condyloid

• Thumb – Saddle

• Neck – Pivot

• Carpals – Gliding

Types of Movement

• Flexion = bend

• Extension = straighten

• Abduction = "AB-ducted" = away from body

• Adduction = "ADD" to the body

• Rotation = twist

• Circumduction = "circle the limb"

.Muscle Roles

• Agonist = main lifter

• Antagonist = chill, controlling friend

• Fixator = holds everything stable

• Synergist = helps the lifter

Planes & Axes

🏃 Think: “Sagittal Plane = Sit-ups”

• Sagittal → forward/backward

• Frontal → side to side (star jumps)

• Transverse → rotation (golf swing)

🪢 Axes go perpendicular to planes:

• Sagittal plane → Transverse axis

• Frontal plane → Sagittal axis

• Transverse plane → Longitudinal axis

🎵 “Planes cut you, axes spin you!”

Origin vs Insertion

• Origin = stationary bone

• Insertion = bone that moves

  song: “Origin is Over here, it stays put —
  Insertion moves when I lift my foot!”

Newton’s Laws in Sport

1st Law (Inertia): Ball stays still unless kicked.

2nd Law (F=ma): Heavier ball needs more force to accelerate.

3rd Law (Action/Reaction): Push ground, ground pushes back.

⚽ Easy way to remember: "Inertia, Acceleration, Equal Reaction"

VO₂ Max and Oxygen Deficit

• VO₂ max = max oxygen you can use — fitness marker.

• Oxygen deficit = starting effort before oxygen catches up.

• EPOC = excess oxygen after exercise to recover.

“Debt now, pay oxygen later.”

Hormonal Regulation of Glucose

• Insulin: Lowers blood sugar (stores glucose)

• Glucagon: Raises blood sugar (releases glucose)

“Insulin INsulin — brings sugar IN cells.”

Arousal Theories (Inverted-U, Catastrophe Theory, etc.)

• Drive Theory: Arousal ↑ → performance ↑

• Inverted-U: Moderate arousal = best

• Catastrophe: If arousal + anxiety too high → complete drop

“Too chill = lazy, too hyped = shaky, just right = peak!”

Attribution Theory

• Internal-stable = ability

• Internal-unstable = effort

• External-stable = task difficulty

• External-unstable = luck

I (internal) can change effort, not ability. They (external) control luck and tasks.

Social Facilitation vs Social Inhibition

• Facilitation = others present → better performance (easy/well-learned tasks)

• Inhibition = others present → worse performance (complex/new tasks)

Option D) Glycemic Index (GI)

• High GI = fast spike (e.g. white bread)

• Low GI = slow release (e.g. oats)

High GI = High speed 🚀, Low GI = Lasts longer 🐢”

Option D) Macronutrient Recommendations

• Carbs = ~55-60%

• Fat = ~25-30%

• Protein = ~10-15%

C-F-P → Carbs First Priority

Energy Balance and Body Composition

• Energy balance = calories in vs out

• Positive balance = weight gain

• Negative balance = weight loss

In = Up, Out = Down

Water and Electrolyte Balance

• Sweating loses both water + salt

• Leads to fatigue, cramps, heat stroke

Supplementation and Ergogenic Aids

• Caffeine = alertness

• Creatine = strength bursts

• Bicarbonate = buffers lactic acid

• Sodium = hydration support

• Iron = oxygen carrying

Caffeine = Speed Boost, Creatine = Power Up, Bicarbonate = Shield!

Systolic Pressure (Top Number)

The pressure when the heart contracts (pumps blood out)

• It’s the higher number

• Think: “Squeeze = Systolic”

Diastolic Pressure (Bottom Number)

• The pressure when the heart relaxes (fills with blood)

• It’s the lower number

• Think: “Down time = Diastolic”

✅ Example: In 120/80 mmHg → 80 is diastolic

Ventilation

➡ The movement of air in and out of the lungs (breathing).

🧠 Memory Trick:Venti = Vent (air in/out)

Pulmonary Ventilation (VE)

🧮 Formula: VE = Tidal Volume × Breathing Rate

Tidal Volume (TV)

➡ The amount of air breathed in or out per breath.

💡 Think: a tidal wave of air with each breath 🌊

Breathing Rate (BR)

➡ The number of breaths taken per minute.

😮‍💨 Normal at rest: ~12–20 breaths/min

Inspiratory Reserve Volume (IRV)

➡ The extra air you can inhale after a normal breath in.

📈 Think: "IRV = Inhale Really Vastly"

Expiratory Reserve Volume (ERV)

➡ The extra air you can force out after a normal breath out.

📉 Think: "ERV = Exhale Really Vigorously"

Residual Volume (RV)

➡ The air that remains in the lungs after you’ve exhaled as much as possible.

🚫 You can’t get rid of this — it prevents lung collapse.

🧠 “R = Remains in lungs”

Vital Capacity (VC)

➡ The maximum amount of air you can exhale after a full inhale.

🧮 Formula: VC = TV + IRV + ERV

🧠 “Vital = Very big breath!”

Total Lung Capacity (TLC)

➡ The total volume of the lungs after a maximal inhalation.

🧮 Formula: TLC = VC + RV

🧠 “Total = everything your lungs can hold.”

Minute Ventilation (same as Pulmonary Ventilation)

➡ Total air in/out per minute.

🧠 Just remember: VE = TV × BR