First responders: patterns, swelling, and complement

Science · The Human Body · ages 21-22

Name ______________________ Date ____________

Which cells release the histamine that starts acute inflammation?
- Mast cells
- Red blood cells
- Platelets
What does a pattern recognition receptor grip?
- One unique protein of a single virus strain
- Fragments of your own healthy proteins
- Marks shared by whole microbe classes
Innate defence works within minutes without prior exposure to the microbe.
Circle one: True False
What causes the swelling and the pain of inflammation?
- Swelling from extra red cells, pain from cold vessels
- Swelling from clotted vessels, pain from low blood flow
- Swelling from leaked fluid, pain from chemical irritation and pressure
Why does an inflamed wound feel hot and look red?
- Dead cells pile up and block the vessels
- Extra blood flow from widened vessels
- Phagocytes consume all local oxygen
Beyond marking the target, what does activated complement do?
- It bursts membranes, coats microbes, and recruits inflammation
- It carries oxygen to the infected tissue
- It builds antibodies against the pathogen
A response that recognises whole classes of microbes at once can still tell your own healthy cells apart from infected ones.
Circle one: True False
A student says phagocytes only eat microbes and change nothing else. What is missing?
- Phagocytes only work after antibodies arrive
- Phagocytes also release alarm signals that call reinforcements
- Phagocytes cannot leave the bloodstream

Answer key

For grown-ups. Fold this page away before handing over the rest.

Mast cells · Resident mast cells sense damage and release histamine onto nearby vessels.
Marks shared by whole microbe classes · Shared marks let the first defence fire without ever meeting the microbe before.
True · Ready-made receptors need no training, so the attack starts at once.
Swelling from leaked fluid, pain from chemical irritation and pressure · Leaky vessels flood the tissue, and the chemicals plus pressure stimulate nerves.
Extra blood flow from widened vessels · Histamine widens vessels, so more warm blood reaches the site.
It bursts membranes, coats microbes, and recruits inflammation · Complement lyses targets, invites phagocytes, and its C5a signal calls reinforcements.
True · Shared microbe marks differ from host molecules, so self is ignored while classes of invaders are caught.
Phagocytes also release alarm signals that call reinforcements · Engulfing is half the job; activated phagocytes also broadcast proinflammatory chemicals.