GCSE · Biology · Edexcel · Spec 1BI0

Ciliated epithelial cells

Right now, tiny hairs on the cells lining your airways are beating in step, sweeping mucus up and out of your lungs.

Biology · Cell structure

Spot the difference

Showing 3 layers: Cell parts, Cilia, Mucus

Layers

Explore

switch the cilia off, then back on

Now add the mucus. It sits in a layer on top of the cilia, and it is exactly what the cilia move.

A ciliated cell beside the model animal cell. Switch the cilia and the mucus off and on, then tap each part to see what it tells you.

Biology · Anatomy

Where ciliated cells work

Showing 3 layers: Airways, Ciliated lining, Mucus direction

Layers

Explore

follow the arrows

Every arrow points the same way: from the bronchi, up the trachea and out. Mucus is moved away from the lungs, never down into them.

The airways of the respiratory system. Switch on the ciliated lining and the direction the mucus moves, then tap each part.

One beat of a cilium

Stage 1 of 4: Upright. paused

Upright · 1/4step round the beat

The cilium stands up straight, with its tip reaching into the layer of mucus above.

Press play or step through the beat. Watch the cilium end up exactly where it started, ready to go again.

What do you think?

What do cilia actually do?

You now know where ciliated cells are and what their cilia look like. Before you go on, be honest about what you think the cilia are for.

Which is closest to what you think right now?

Cilia filter the air, catching things as it flows past them.Cilia push mucus down into the lungs.Cilia waft air in and out of the lungs to help us breathe.Cilia sweep mucus along, up and out of the airways.

How sure are you?

I'm sureI think soI'm guessing

Cilia filter the air, catching things as it flows past them.

This is a common misconception

Very common, and it's the word 'filter' that catches people out. Cilia aren't a sieve or a net. Their job is to move something, and that something is the mucus lying on top of them. Swap 'filter the air' for 'move mucus' and you're there.

Cilia push mucus down into the lungs.

This is a common misconception

You've got the right thing, mucus, but it's going the wrong way. Cilia move mucus up the bronchi and trachea, away from the lungs and out of the airways. Direction matters: 'down into the lungs' is the opposite of their job.

Cilia waft air in and out of the lungs to help us breathe.

This is a common misconception

Moving air isn't their job. Cilia work on the thin layer of mucus sitting right on top of them, and that's what they move. Keep it straight: cilia move mucus, and they sweep it up and out.

Cilia sweep mucus along, up and out of the airways.

This matches the evidence

Yes. Both halves are right: what they move (mucus) and which way (up and out of the trachea and bronchi, away from the lungs). That pair is exactly what an explanation needs.

Cilia move mucus, and they move it up and out. If an answer about cilia doesn't say both, it isn't finished.

Your turn

Put the whole chain together

Explain how a ciliated cell is adapted to carry out its function. [4 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

It lines the airways: the trachea and/or the bronchi. (1 mark)
Its surface is covered in cilia (tiny hair-like structures). (1 mark)
The cilia move/beat/waft together, again and again. (1 mark)
This moves mucus up and out of the airways / away from the lungs. (1 mark)

Model answer

Ciliated cells line the trachea and the bronchi. The surface of each cell is covered in tiny hair-like cilia. The cilia on many cells beat together over and over, in a wafting motion, and this sweeps mucus up and out of the airways, away from the lungs.

Where it is, what it has, what that does, and the result. Four links, and together they make a full explanation.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

The cells whose tiny hairs sweep mucus up and out of your airways.

What you need to know

A specialised cell has a structure (its shape and the parts it contains) adapted to carry out one specific job.
Ciliated cells line the airways of the respiratory system: the trachea and the bronchi.
The surface of a ciliated cell is covered in tiny hair-like structures called cilia. The model animal cell has none.
The job of ciliated cells is to move mucus up and out of the airways, away from the lungs.
The cilia on many cells beat together, over and over (upright, then flatter, then upright again), to sweep the mucus along.

The big picture

A ciliated cell is a specialised cell: its structure is fitted to one particular job. Set it beside the model animal cell and the difference jumps out. Its surface is covered in tiny hair-like structures called cilia. Ciliated cells line the trachea and the bronchi, and their job is to move mucus up and out of the airways. They do it by beating their cilia again and again (upright, then flatter, then upright again), with many cilia moving together so the mucus is carried steadily along.

Key points

1Specialised cell = structure fitted to a specific function.

2Ciliated cells: found lining the trachea and bronchi.

3Adaptation: a surface covered in cilia.

4Function: moving mucus up and out, away from the lungs.

5How: many cilia beating together, in a repeated wafting motion.

.we-_R_18slubsnpfiv5ubrb_ [data-we-step]{display:flex !important}.we-_R_18slubsnpfiv5ubrb_ [data-we-solution]{display:block !important}.we-_R_18slubsnpfiv5ubrb_ [data-we-reveal]{display:none !important}

Worked example

Problem

A ciliated cell and the model animal cell both have a nucleus, a cell membrane and cytoplasm. Explain why none of these parts can be the adaptation that suits a ciliated cell to its job, and name the part that is.

⚠ Watch out

Writing that cilia 'help you breathe' or 'clean the air'. Neither says what cilia actually do. Name what they move (mucus) and which way it goes (up and out of the airways, away from the lungs).

🧠

Memory hook

Crowd-surf the mucus out: thousands of tiny hands (the cilia), each giving a small push, all in the same direction, up and out.

✓

Check yourself

Cover the page. What does a ciliated cell have that the model animal cell doesn't, where are these cells found, and which way do they move mucus?

Flashcards

(9)

What are cilia?

Tiny hair-like structures covering the surface of a ciliated cell.

Where are ciliated cells found?

Lining the airways: the trachea and the bronchi.

Which organ system do the trachea and bronchi belong to?

The respiratory system.

What is the function of ciliated cells?

To move mucus up and out of the airways, away from the lungs.

What is a specialised cell?

A cell whose structure (its shape and the parts it contains) is adapted to carry out a specific function.

Which structure does a ciliated cell have that the model animal cell lacks?

Cilia covering its surface.

Describe the shape of one beat of a cilium.

Upright, then it sweeps over to lie flatter, then it comes back upright again, and repeats.

Why doesn't a cilium push the mucus backwards as it returns to upright?

It bends low and stays close to the cell surface on the way back, so it doesn't drag the mucus with it.

Why do many cilia need to beat together?

One beat moves mucus only a tiny way. Many cilia beating together, over and over and in the same direction, carry it steadily along.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

Learning with Lightbulb is opening soon

You can use this lesson now. Join the waitlist and we'll let you know when the full Lightbulb experience is ready.

Keep me posted

One beat of a cilium

What do cilia actually do?

Put the whole chain together

More Edexcel GCSE Biology topics