E. Animals: Structure and Function · Animals: Structure and Function

Technologies for Seeing and Treating Internal Systems

E1.1 E3.2 E3.3 A1.3 A1.9 A1.11 A2.1 A2.2About 70 minutes

Learning goals

I can explain how endoscopy, laser treatments, cardiac imaging and catheter-based procedures work and what each reveals or treats.
I can evaluate a medical technology using criteria such as benefits, risks, invasiveness, cost and access.
I can describe Canadian contributions to understanding and treating the digestive, respiratory and circulatory systems.
I can name careers that use these technologies and the training they require.

Words to know

endoscope
A thin tube with a light and camera (and a channel for tools) that is passed into the body to view and treat internal organs.

biopsy
A small sample of tissue removed for examination under a microscope.

echocardiogram
An ultrasound image of the heart, showing its chambers, valves and blood flow.

angiography
Imaging of blood vessels using a contrast dye and X-rays (or CT or MRI).

angioplasty / stent
Opening a narrowed artery with a small balloon / a mesh tube left in place to keep it open.

photodynamic therapy
A treatment in which a light-sensitive drug is given and then activated by laser light to destroy abnormal cells.

invasive / non-invasive
Requiring entry into the body (a cut or a tube) / not requiring it.

perfusionist
A health professional who operates the heart-lung machine during heart surgery.

Seeing without opening

A century ago, the only way to see inside a living person's stomach or coronary arteries was surgery, and much of what was learned about internal anatomy came from dissecting people after death. Today a doctor can watch a heart valve open and close, look at the lining of a colon, or reopen a blocked coronary artery through a tube inserted at the wrist, often while the patient is awake. These technologies have changed both our understanding of internal systems and how we treat their disorders.

Remember from Grade 10

In Grade 10 (Tissues, Organs, and Systems) you compared X-rays, CT, MRI and ultrasound, including ionizing radiation and wait times, and met endoscopy and pulse oximeters. This lesson focuses on the technologies used for the digestive, respiratory and circulatory systems, many of which both diagnose and treat, and on how to evaluate them.

Endoscopy

An endoscope is a long, flexible tube with a light and a tiny video camera at its tip (older ones used bundles of optical fibres that carry light by total internal reflection). It also has a working channel for tools.

Gastroscopy (upper endoscopy) goes through the mouth to the esophagus, stomach and duodenum: it can find ulcers, inflammation, celiac damage and tumours, and take biopsies (including tests for H. pylori).
Colonoscopy examines the colon: doctors can find and remove polyps (growths that may become cancer) during the same procedure. In Ontario, people aged 50 to 74 at average risk are screened for colon cancer with a home stool test (FIT), and those with an abnormal result are referred for colonoscopy.
Bronchoscopy examines the trachea and bronchi: it can remove blockages, take samples and guide treatment of lung tumours.
Capsule endoscopy: the patient swallows a pill-sized camera that takes thousands of pictures as it travels through the small intestine, a part that ordinary endoscopes can't easily reach.

Benefits: direct view of the lining; diagnosis and treatment in one procedure; no large incision. Risks: usually small but real: bleeding, rarely a tear in the gut wall, and reactions to sedation.

An endoscope: a flexible tube with a camera, lights and a working channel at its tip, controlled from a handle and viewed on a screen. (Schematic.)

Lasers in lung surgery

A laser produces an intense, narrow beam of light of one wavelength that can cut, seal or destroy tissue very precisely. In the lungs:

Through a bronchoscope, a laser can burn away a tumour that is blocking an airway, quickly improving breathing.
In photodynamic therapy, the patient receives a light-sensitive drug that collects in abnormal cells; laser light delivered through the bronchoscope then activates it, destroying those cells while sparing most nearby tissue.
Lasers can also seal small blood vessels as they cut, reducing bleeding.

These are mostly palliative or used for small, early cancers; larger tumours are treated with surgery, radiation or drugs.

Technologies for the heart and blood vessels

ECG (electrical activity, from the heart lesson). A Holter monitor records an ECG for a day or more to catch irregular rhythms.
Exercise stress test: an ECG (and blood pressure) recorded while the person walks on a treadmill, revealing narrowed coronary arteries that only cause problems during exertion.
Echocardiogram: ultrasound images of the beating heart. Doppler ultrasound shows the direction and speed of blood flow, revealing leaky or narrowed valves and holes such as an open foramen ovale. No radiation.
Coronary angiography: a thin catheter is threaded from an artery in the wrist or groin up to the heart. Contrast dye is injected into the coronary arteries while X-ray video is recorded, showing exactly where they are narrowed.
Angioplasty and stents: during the same procedure, a tiny balloon is inflated in the narrowed spot, pressing the plaque back, and a mesh stent is left to hold the artery open. During a heart attack, this can reopen a blocked artery within minutes of arrival at a heart centre.
CT and MRI of the heart and vessels, and ultrasound at the bedside to check for internal bleeding after an injury.
Treatment devices: pacemakers; implantable cardioverter-defibrillators (ICDs) that shock a dangerous rhythm back to normal; the heart-lung machine, which takes over pumping and gas exchange during open-heart surgery; and ventricular assist devices that help a failing heart pump.

Angioplasty and stenting. A catheter carries a deflated balloon and a folded mesh stent to the plaque; the balloon inflates and expands the stent; the stent stays to keep the artery open. (Schematic; not to scale.)

Canadian contributions

Insulin (1921–22, Toronto): Frederick Banting, Charles Best, James Collip and John Macleod isolated insulin from the pancreas, the same organ that sends enzymes into the duodenum, and turned type 1 diabetes from a fatal disease into a treatable one.
Heart surgery (1950, Toronto): Wilfred Bigelow showed that cooling the body (hypothermia) lowers its oxygen needs, so the heart can be stopped briefly for surgery; with John Callaghan and engineer John Hopps he also built an early external pacemaker.
Lung transplants (Toronto General Hospital): a team led by Joel Cooper performed the world's first successful single-lung transplant in 1983 and first successful double-lung transplant in 1986.
Cystic fibrosis gene (1989, SickKids, Toronto): found by a team led by Lap-Chee Tsui.
Ex vivo lung perfusion (Toronto, late 2000s): a Toronto team developed a way to keep donor lungs breathing and perfused outside the body, so they can be checked and improved before transplant, increasing the number of usable donor lungs.

These show science as a team effort, often linking medicine and engineering.

Some Canadian milestones in understanding and treating internal systems. (Timeline to scale by year.)

Worked example

Example 1: Evaluating a screening technology

Ontario screens average-risk adults aged 50 to 74 for colon cancer with a FIT (a home test that detects tiny amounts of blood in stool), and only people with an abnormal FIT have a colonoscopy. Evaluate this two-step approach using benefit, risk, cost and access.

FIT: non-invasive, done at home, inexpensive, easy to mail in → many more people can be screened, including those in rural and remote communities. But it can miss some polyps and cancers (false negatives) and can be positive for other reasons (false positives).
Colonoscopy: sees the whole colon and can remove polyps immediately, but it is invasive (bowel preparation, sedation, small risk of bleeding or perforation), more costly, and needs specialists, so wait times can be long.
Combined: FIT screens large numbers cheaply and safely; colonoscopy is saved for those most likely to benefit, reducing risks and wait times for everyone.
Conclusion: the two-step approach balances reach (FIT) with accuracy and treatment (colonoscopy). People with higher risk (e.g., a strong family history) are usually sent straight to colonoscopy.

A good evaluation names criteria, weighs pros and cons for each option, and reaches a justified conclusion.

Worked example

Example 2: Choosing the right test

Match each patient to the most useful first test and justify: (a) a teen with a heart murmur; (b) a 60-year-old with chest pain during exercise that eases with rest; (c) a person having a heart attack right now; (d) someone with occasional palpitations that never happen at the clinic.

(a) Echocardiogram: shows valve structure and blood flow (a leaky or narrowed valve), with no radiation; good for a young person.
(b) Exercise stress test (possibly followed by angiography): symptoms appear only with exertion, suggesting narrowed coronary arteries.
(c) Emergency ECG, then angiography with angioplasty/stent to reopen the blocked artery as fast as possible.
(d) Holter monitor (or a longer-term wearable recorder): records the rhythm over a day or more to catch the event.

The best test depends on the question being asked, the urgency, and the risk of the test itself.

Careers

Gastroenterologists, respirologists and cardiologists: physicians specializing in the digestive, respiratory and circulatory systems (medical school plus specialty training).
Respiratory therapists: manage ventilators and breathing treatments, and do lung-function testing; a regulated profession in Ontario.
Cardiovascular perfusionists: run the heart-lung machine during surgery; in Ontario, trained at the Michener Institute.
Diagnostic medical sonographers: perform ultrasound and echocardiograms.
Cardiology technologists: perform ECGs, stress tests and Holter monitoring.
Endoscopy nurses and biomedical engineers, who design and maintain devices like stents, pacemakers and endoscopes.

Hands-on activity

Explore like an endoscope, and guide light like an optical fibre

Part A: The endoscopy box. You need: a shoebox with a lid, a phone with a camera and flashlight, tape, a ruler, and small objects (beads, buttons, a bit of crumpled foil).

Your partner secretly arranges 3 to 5 small objects inside the box ("polyps") and closes it. Cut (with a grown-up) one hole in the end just big enough for the phone's camera.
Turn on the flashlight and record video through the hole while slowly moving and tilting the phone. Don't open the lid!
From the video only, draw a map of what's inside and where. Then open the box and check.
List three limitations of your "endoscope" (for example: field of view, depth perception, reaching around corners) and how real endoscopes deal with them.

Part B: Light in a stream of water. You need: a clear plastic bottle, a nail (a grown-up makes a small hole near the bottom), a sink, a dark room and a small flashlight (never use a laser pointer: they can damage eyes).

Cover the hole and fill the bottle with water. Darken the room.
Hold the flashlight tight against the bottle on the side opposite the hole, pointing at it. Uncover the hole and put your finger in the curving stream.

What to look for: in Part A, you'll probably miss or misplace something, which shows why doctors use bright lights, steerable tips, and careful systematic movement. In Part B, a spot of light appears on your finger where it meets the stream: the light travelled along the curved stream by total internal reflection, the same principle that lets optical fibres carry light around the bends of an endoscope.

Just for fun

Why do endoscopes never get lost on the way through the digestive tract?

They always follow their gut.

Your turn

What is an endoscope, and what can its working channel be used for?

Name the endoscopy used for (a) the stomach, (b) the colon, (c) the bronchi.

How can a laser help a patient whose airway is blocked by a tumour?

What does an echocardiogram show, and does it use ionizing radiation?

Describe angioplasty and stenting.

Give two Canadian contributions to understanding or treating internal systems.

Name two careers that use these technologies.

More practice: warm-up

What is a biopsy?

What does a Holter monitor record?

What is a stent?

What does the heart-lung machine do?

What is capsule endoscopy?

More practice: on your own

Why is coronary angiography called invasive, while an echocardiogram is non-invasive?

Give one benefit and one risk of coronary angiography.

Why was Bigelow's discovery about hypothermia important for heart surgery?

How does ex vivo lung perfusion help more patients get lung transplants?

Explain why access to some technologies is unequal in Ontario.

Challenge

Create a set of four criteria and use them to compare gastroscopy with a breath test for detecting H. pylori (the breath test measures labelled CO₂ produced when the bacteria break down a swallowed test substance).

A technology can improve our understanding of a system as well as treatment. Explain how echocardiography with Doppler has done both.

Write a short, evidence-based argument (4 to 5 sentences) for or against this statement: "Because stents work so well, people with heart disease don't need to change their lifestyle."

Check your understanding

Quiz

Which procedure lets a doctor see and remove polyps in the colon?

Coronary angiography shows narrowed arteries using:

Which technology uses no ionizing radiation?

Who led the Toronto team that performed the first successful single-lung transplant in 1983?

In photodynamic therapy, the laser is used to:

Which professional operates the heart-lung machine during heart surgery?

For parents and teachers

Big idea: E1.1 asks students to evaluate the importance of technologies, including Canadian contributions, to our understanding of internal body systems (the curriculum mentions endoscopes, lasers in lung surgery, and imaging for injuries and cardiovascular disorders). This lesson builds on the Grade 10 imaging lesson with technologies that diagnose and treat, practises evaluating with criteria (A1.9, A1.11), and covers careers and Canadian scientists (A2.1, A2.2).

How to help: If anyone in the family has had an endoscopy, an echocardiogram or a stent (and is comfortable sharing), your teen could ask what it was like. Do the water-stream light demo together in a dark bathroom.

Common difficulties:

Listing facts instead of evaluating. An evaluation needs criteria, pros and cons, and a justified conclusion.
Mixing up angiography (imaging) and angioplasty (treatment).

Safety: never use laser pointers for the light demo; a grown-up makes the holes in the box and bottle.