Diagramz

What's going wrong inside — drawn out and explained in plain language 14 conditions

Each condition below pairs a clear anatomical diagram with a short, jargon-light explanation: what it is, what's physically happening (the pathology), and how it tends to feel (the symptoms). The pictures are simplified on purpose — they're meant to make the idea click, not to be textbook-perfect.

This is general education, not medical advice. It can't diagnose you or replace a clinician. If you have severe, sudden, or worsening symptoms — especially the “red flags” noted in each section — seek urgent medical care.

Kidney Stones

Urinary Nephrolithiasis
Diagram of a kidney, ureter and bladder with a stone lodged in the ureter. A bean-shaped kidney drains through a long ureter tube into the bladder. A hard stone is stuck partway down the ureter, blocking flow and causing urine to back up and swell the kidney above it.
A stone wedged in the ureter dams the urine and stretches the kidney behind it — the cause of the classic, crippling pain.

What it is

A kidney stone is a small, hard pebble that forms when minerals in the urine (often calcium) become too concentrated and crystallize. Trouble starts when a stone leaves the kidney and gets stuck in the ureter, the narrow tube to the bladder.

What's happening

The stuck stone blocks urine like a cork in a pipe. Urine keeps being made, so it backs up and stretches the kidney and ureter. That stretching, plus the ureter squeezing to push the stone along, is what hurts.

Symptoms

  • Sudden, severe waves of pain in the flank/side that may radiate to the groin
  • Pain so intense it's hard to sit still ("writhing")
  • Blood in the urine (pink, red or brown)
  • Nausea, vomiting, frequent urge to pee
Red flag: stone pain with fever or chills can mean an infected, blocked kidney — a true emergency. Seek care now.

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Gallstones

Digestive Cholelithiasis
Diagram of the liver, gallbladder and bile ducts with stones blocking the duct. The gallbladder sits under the liver and stores bile. Stones have formed inside it; one has slipped into the duct that drains toward the intestine and is blocking the exit.
Stones form in the gallbladder; pain begins when one jams the neck or duct and bile can't drain after a fatty meal.

What it is

Gallstones are hardened lumps (usually cholesterol) that form in the gallbladder, the small pouch under the liver that stores bile — the fluid used to digest fat.

What's happening

After a fatty meal the gallbladder squeezes to push bile out. If a stone plugs the exit, the gallbladder contracts against a blockage. That cramping pressure causes pain; if the blockage lasts, the wall becomes inflamed and infected (cholecystitis).

Symptoms

  • Pain in the upper-right belly, often after fatty food
  • Pain that can spread to the right shoulder blade
  • Nausea and vomiting
  • Bloating and indigestion
Red flag: pain with fever, or yellowing of the eyes/skin (jaundice) suggests infection or a blocked main bile duct — get urgent care.

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Deep Vein Thrombosis

Vascular DVT
Diagram of a leg's deep vein with a blood clot blocking it. A cross-section of a leg showing the deep vein running down it. A clot has formed inside the vein, blocking blood return so the leg below swells.
A clot in a deep leg vein blocks the return of blood, so fluid backs up and the leg below swells, warms and aches.

What it is

DVT is a blood clot that forms in one of the deep veins, usually in the calf or thigh. Veins carry blood back toward the heart, so a clot here dams the return flow.

What's happening

Blood that sits still (long flights, bed rest, surgery), is extra sticky, or flows through a damaged vein wall can clot. The clot plugs the vein; blood and fluid pool below it, swelling the limb. The danger is a piece breaking off and travelling to the lungs.

Symptoms

  • Swelling in one leg (often the calf)
  • Aching or cramping pain, often worse standing
  • Warmth and red or darkened skin over the area
  • The leg may feel tight or heavy
Red flag: sudden shortness of breath, chest pain, or coughing blood can mean the clot has reached the lungs (see below) — call emergency services.

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Pulmonary Embolism

Respiratory PE
Diagram of the lungs with a clot lodged in a pulmonary artery. Blood travels from the heart into the arteries of both lungs. A clot that broke off from a leg vein has lodged in a lung artery, blocking blood from reaching part of the lung.
A clot (often a piece of a leg DVT) wedges in a lung artery, cutting blood flow to that part of the lung.

What it is

A pulmonary embolism is a blockage in one of the arteries of the lungs, almost always caused by a clot that broke loose from a deep vein elsewhere (commonly the leg) and travelled up through the heart.

What's happening

The lungs add oxygen to blood. When a clot plugs a lung artery, blood can't reach that section to pick up oxygen, and the heart suddenly has to push against a blocked pipe. A large clot can strain the heart dangerously.

Symptoms

  • Sudden shortness of breath
  • Sharp chest pain, often worse with a deep breath
  • Fast heartbeat
  • Coughing, sometimes with blood; light-headedness or fainting
Red flag: PE can be life-threatening within hours. Sudden breathlessness or chest pain — especially with a swollen leg — needs emergency care immediately.

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Aortic Dissection

Vascular Torn aorta wall
Cross-section of the aorta showing blood tearing between the wall layers. The aorta is the body's main artery. Its inner lining has torn, letting high-pressure blood force its way between the layers of the wall and create a second, false channel.
High-pressure blood rips through the inner lining and splits the aortic wall, carving a dangerous "false channel" alongside the true one.

What it is

The aorta is the large artery carrying blood out of the heart. In a dissection, the inner lining tears and blood is forced into the wall itself, splitting its layers apart.

What's happening

Blood under high pressure drives between the wall layers, creating a false channel. This weakens the aorta (it can rupture), and the flap can block branches feeding the heart, brain, or organs — starving them of blood.

Symptoms

  • Sudden, severe chest or upper-back pain, often described as "tearing" or "ripping"
  • Pain that may move as the tear extends
  • A big difference in blood pressure or pulse between arms
  • Fainting, stroke-like symptoms, or sudden collapse
Red flag: this is a time-critical emergency. Sudden tearing chest/back pain needs emergency services now — do not wait.

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Abdominal Aortic Aneurysm

Vascular AAA
Diagram of the abdominal aorta with a balloon-like bulge. The aorta runs down through the abdomen and splits into the two leg arteries. A section of its wall has weakened and ballooned outward into a bulge.
A weakened patch of the aorta stretches into a balloon. The wider it grows, the thinner and more rupture-prone the wall becomes.

What it is

An aneurysm is a balloon-like bulge where an artery wall has weakened. In an AAA it's the section of the aorta running through the belly that stretches outward.

What's happening

Years of wear (high blood pressure, smoking, aging) weaken the wall. Under constant pressure the weak spot stretches wider — and like an over-inflated balloon, a larger, thinner wall is closer to bursting. Most cause no symptoms until they leak or rupture.

Symptoms

  • Often silent — found by chance on a scan
  • Sometimes a deep, throbbing feeling in the belly
  • Steady pain in the belly, flank, or lower back
  • A pulsing lump near the navel
Red flag: sudden severe belly/back pain, faintness, or collapse may mean it's rupturing — an immediate, life-threatening emergency.

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Heart Attack

Cardiac Myocardial infarction
Diagram of the heart with a blocked coronary artery and damaged muscle. The heart's own muscle is fed by coronary arteries on its surface. One artery is blocked by a clot, and the area of muscle beyond the blockage is being damaged from lack of blood.
A clot blocks a coronary artery; the heart muscle it supplied is starved of oxygen and begins to die — the more time passes, the more is lost.

What it is

The heart is a muscle, and it has its own supply pipes — the coronary arteries — running across its surface. A heart attack is a sudden blockage of one of these arteries.

What's happening

A fatty deposit in the artery wall cracks open, and a blood clot forms on top, plugging the pipe. The muscle beyond it stops getting oxygen and starts to die. Restoring flow fast ("time is muscle") limits the damage.

Symptoms

  • Chest pressure, tightness or heaviness (may feel like a band)
  • Pain spreading to the arm, jaw, neck or back
  • Shortness of breath, cold sweat, nausea
  • Symptoms can be subtler in women, older adults and people with diabetes
Red flag: chest pain lasting more than a few minutes, or with sweating/breathlessness, is an emergency — call emergency services immediately.

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Ischemic Stroke

Neurological "Brain attack"
Diagram of the brain with a blocked artery and an affected region. An artery supplying the brain is blocked by a clot. The region of brain fed by that vessel is no longer receiving blood and its function is lost.
A clot blocks an artery in the brain; the territory it supplied loses oxygen, and the abilities controlled by that area fail.

What it is

An ischemic stroke is a sudden loss of blood supply to part of the brain, usually because a clot blocks a brain artery. (A less common type is a bleed.) Brain cells need a constant blood supply and fail quickly without it.

What's happening

With the artery blocked, the affected brain region stops working — and within minutes to hours those cells begin to die. Because different areas control different functions, the symptoms point to where the blockage is.

Symptoms — remember FAST

  • Face drooping on one side
  • Arm weakness, often one-sided
  • Speech slurred or garbled
  • Time to call emergency services — act fast
Red flag: stroke treatments work best within hours. Any sudden weakness, speech trouble, or facial droop — call emergency services immediately, even if it passes.

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Appendicitis

Digestive Inflamed appendix
Diagram of the large intestine with an inflamed appendix in the lower right abdomen. The appendix is a small finger-shaped pouch hanging off the start of the large intestine in the lower right belly. It is blocked, swollen and inflamed.
The appendix becomes blocked and swells; pain typically starts near the navel then settles into the lower-right belly.

What it is

The appendix is a small, finger-shaped dead-end pouch attached to the start of the large intestine, low on the right side of the belly. Appendicitis is when it becomes blocked, inflamed and swollen.

What's happening

When the appendix's opening gets blocked (by hardened stool, swelling, rarely a seed), pressure builds inside, bacteria multiply, and the wall inflames. If untreated it can burst, spilling infection into the belly.

Symptoms

  • Pain that often starts around the navel, then shifts to the lower-right belly
  • Pain worse with movement, coughing, or pressing then releasing
  • Loss of appetite, nausea, vomiting
  • Low-grade fever
Red flag: sudden relief followed by spreading, severe belly pain and high fever can mean the appendix has burst — seek urgent care.

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Diverticulitis

Digestive Inflamed pouches
Diagram of the colon wall with small pouches, one of them inflamed. A length of large intestine showing several small pouches bulging out from the wall. One pouch has become inflamed and infected.
Small pouches push out through weak spots in the colon wall; trouble starts when one becomes blocked, inflamed and infected.

What it is

Over time, small pouches (diverticula) can balloon out through weak spots in the wall of the large intestine — very common with age and usually harmless. Diverticulitis is when one of these pouches becomes inflamed or infected.

What's happening

A pouch gets blocked or its thin wall is irritated; bacteria build up and the area inflames. This can stay localized, or progress to a small abscess or a tiny perforation that leaks into the belly.

Symptoms

  • Pain in the lower-left belly (sometimes constant for days)
  • Fever and feeling generally unwell
  • Change in bowel habit — constipation or diarrhea
  • Bloating, nausea
Red flag: high fever, a rigid or severely tender belly, or heavy rectal bleeding needs urgent assessment.

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Bowel Obstruction

Digestive Blocked intestine
Diagram of intestine blocked at one point with swollen loops above it. A length of intestine is blocked at one point. The loops before the blockage are stretched and swollen with trapped food, fluid and gas, while the bowel beyond it is empty and flat.
Something blocks the intestine; contents pile up and balloon the bowel above, while the bowel beyond empties and flattens.

What it is

A bowel obstruction is a blockage that stops food, fluid and gas from passing through the intestine. Common causes include scar tissue from past surgery (adhesions), hernias, and tumors.

What's happening

Above the blockage, contents and gas pile up and stretch the bowel, which then can't move things along. The trapped, swollen bowel causes cramping pain and vomiting; if its blood supply gets pinched, the wall can be damaged.

Symptoms

  • Cramping belly pain that comes in waves
  • A bloated, distended belly
  • Vomiting (which may smell feculent in low blockages)
  • Inability to pass gas or stool
Red flag: constant severe pain, fever, or a tense rigid belly may mean the bowel is being strangled — an emergency needing urgent surgery assessment.

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Inguinal Hernia

Abdominal wall Groin hernia
Cross-section of the lower abdominal wall with a loop of bowel pushing through a weak spot. A cut-through view of the lower belly wall. There is a weak gap in the muscle, and a loop of intestine is bulging out through it under the skin, forming a lump.
A weak spot in the groin's muscle wall lets a loop of bowel push through, creating a visible bulge that often pops out on straining.

What it is

A hernia is when an internal part — usually a loop of intestine — pushes through a weak spot in the muscle wall that's meant to hold it in. An inguinal hernia happens in the groin, the most common location.

What's happening

The groin has a natural channel that can become a weak point. Pressure from coughing, lifting or straining pushes a bit of bowel through, making a bulge. It often slides back in when lying down — but can become trapped.

Symptoms

  • A bulge in the groin, more obvious when standing, coughing or straining
  • An aching or dragging feeling in the area
  • Bulge that may disappear when lying down
  • Discomfort worse at the end of the day
Red flag: a hernia that becomes hard, very painful, and won't push back in — with vomiting — may be strangled (its blood supply cut off). This is an emergency.

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Pneumothorax

Respiratory Collapsed lung
Diagram of the chest with one lung collapsed by air in the surrounding space. A chest with two lungs. The right lung is full and normal; the left has leaked air into the space around it, and that trapped air has squashed the lung down to a small clump.
Air leaks into the sealed space around a lung; with nothing holding it open, the lung collapses inward like a deflated balloon.

What it is

Your lungs sit in a sealed space and stay inflated thanks to a vacuum-like seal around them. A pneumothorax is when air leaks into that space, breaking the seal and letting the lung collapse.

What's happening

Air escapes — from a small bleb on the lung's surface bursting, or an injury — into the space between lung and chest wall. That trapped air takes up room and presses the lung down so it can't expand to breathe.

Symptoms

  • Sudden, sharp, one-sided chest pain
  • Shortness of breath that came on quickly
  • Fast breathing and heart rate
  • Sometimes follows a tall, thin build or chest injury
Red flag: severe breathlessness, blue lips, or collapse may signal a tension pneumothorax (pressure crushing the heart and other lung) — call emergency services now.

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Ectopic Pregnancy

Reproductive Tubal pregnancy
Diagram of the uterus and fallopian tubes with a pregnancy implanted in a tube. The uterus sits in the centre with a fallopian tube and ovary on each side. Instead of settling in the uterus, a pregnancy has implanted and is growing inside the narrow left fallopian tube, stretching it.
A fertilized egg implants in the narrow fallopian tube instead of the uterus; as it grows, it stretches the tube, which can rupture.

What it is

In pregnancy, a fertilized egg normally travels down the fallopian tube and settles in the uterus. In an ectopic pregnancy it implants somewhere else — most often inside the narrow fallopian tube, which can't accommodate it.

What's happening

The pregnancy grows in a space far too small and not built to stretch. As it enlarges it can split the tube open, causing serious internal bleeding. This typically becomes apparent in the early weeks of pregnancy.

Symptoms

  • One-sided lower belly or pelvic pain
  • Vaginal bleeding or spotting, often with a positive pregnancy test
  • Sometimes shoulder-tip pain (from internal bleeding irritating the diaphragm)
  • Dizziness or faintness
Red flag: severe pelvic pain, faintness or collapse in early pregnancy can mean the tube has ruptured — a life-threatening emergency. Get help immediately.

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