Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

7.2.6Unit 6: Practical Skills in Biology II

The Role of Adrenaline — IAL Edexcel Linear Revision Notes & Topical Questions

5 min read 4 parts Lesson 28 of 48 Unit quiz

📚 IAL Edexcel Linear Hub / Topical Revision
🩺
100% Curriculum Specification Match Lesson Doctor Verified
The only platform with 100% curriculum specification match and verified interactive question banks.
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
0%read

Part 1 of 4Triggering the Response

1
Stress, fear or excitement is detected and sympathetic neurones stimulate the adrenal medulla, part of the adrenal gland.
2
The adrenal medulla secretes adrenaline into the blood, which carries it around the whole body.
3
Adrenaline binds to specific receptors on the cell surface membranes of its target organs.
4
The target cells respond, and the combined effects prepare the body for rapid action.
5
When the threat has passed secretion falls and the effects fade, as the parasympathetic nervous system restores the resting state.

Part 2 of 4Effects of Adrenaline

Heart
  • Heart Adrenaline acts on the sinoatrial node, increasing the frequency of excitation and so raising the heart rate.
Blood flow
  • Blood flow Arterioles supplying the gut and skin constrict, which diverts blood toward the muscles.
Respiration
  • Respiration More oxygen and glucose reach muscle cells, increasing aerobic respiration and the release of energy.
Brain
  • Brain Blood flow to the brain stays constant, as it must always receive a steady supply of oxygen and glucose.
Symptoms
  • Symptoms The typical signs are a faster heartbeat, sweating and a dry mouth.

Part 3 of 4How Adrenaline Works in Cells

How Adrenaline Works in Cells
Receptor
  • Receptor Adrenaline cannot cross the membrane, so it binds to a receptor on the outside of the cell.
Second messenger
  • Second messenger Binding activates a second messenger inside the cell, called cyclic AMP, which is made from ATP.
Cascade
  • Cascade Cyclic AMP activates protein kinases, which trigger a chain of enzyme reactions.
Outcome
  • Outcome The cascade changes enzyme activity, and it can also affect transcription factors and gene expression.
FeatureNervous controlHormonal control
SignalElectrical impulseChemical hormone
RouteNeuronesBlood
SpeedVery fastSlower
DurationShort-livedLonger-lasting

Part 4 of 4Exam Checklist & Tips

7.2.6 – Key Points for the Exam

  • Adrenaline A hormone from the adrenal medulla that prepares the body for fight or flight.
  • Adrenal medulla The inner part of the adrenal gland that secretes adrenaline.
  • Second messenger A molecule inside a cell that relays the signal from a hormone bound at the surface.
  • Cyclic AMP A second messenger made from ATP.
  • Target organ An organ with receptors for a particular hormone.

Common Mistakes

  • Saying adrenaline enters cells directly; it works through a surface receptor and second messenger.
  • Stating that blood flow to the brain falls during fight or flight.
  • Describing hormones as faster than nerve impulses.
  • Forgetting that adrenaline is released after nervous stimulation of the adrenal medulla.

Last updated:

\n