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Blood Vessels · Chapter 2 of 7
Every vessel bigger than a capillary is built from the same three coats. This is the histology chapter: arteriesBlood vessels that carry oxygenated blood away from the heart (except pulmonary arteries, which carr, veinsBlood vessels that return deoxygenated blood to the heart (except pulmonary veins, which carry oxyge and capillariesThe smallest blood vessels where gas, nutrient, and waste exchange occurs between blood and tissues. under the microscope, and the one layer where disease begins.
The question you will answer
Do arteries and veins share the same basicA solution with a pH above 7, having a lower concentration of H⁺ ions. build — and where is the fault line?
Opener · Build a Vessel · about 1½ minutes
The opener is the same narrated animation you will watch in Scene 1.
Watch the opener first. It sets the question; the chapter answers it.
1
Read the chart
Patient chart · Stina
2020 · age 45
Imaging
Coronary calcium sits in the wall of an artery; the phlebolith sits in the wall of a pelvic vein.
Question
Two very different vessels, two findings in their walls. What do the walls have in common?
Background
Decades of raised IL-1β and IL-6.
This chapter writes line 2 of Chart Clue #16.
Your prediction
Her calcium is in an artery wall and her clot is in a vein wall. The layer where vessel disease begins is…
Open the one you’d bet on. Nothing is recorded, and the answer isn’t here — the scenes will test your bet.
The outer coat — the tough collagen that anchors the vessel
Reasonable — it is the thickest coat in a vein. Look closely at what each coat touches.
The middle coat — the smooth muscle that sets diameter
Many people pick the muscle. Hold it while you compare an artery and a vein under the microscope.
The inner lining — the one sheet of cells that touches blood
Hold that thought and see what the lining looks like in each of the three vessel types.
From Stina’s diary
“It stopped the way a phone stops ringing: one day you notice it’s been quiet a long time.”
2
The story
Three short movements: the case, the anatomyThe study of the structure of the human body. and physiologyThe study of how the body functions., then the tie back to Stina. Each links to the scene where you’ll see it move.
I · Where Her Findings Live
Both of Stina’s vascular clues live in vessel walls — calcium in the wall of a coronary artery, an old calcified clot in the wall of a pelvic vein. To make sense of why one vessel hardens and another harbors a clot, you have to start with the wall itself, which follows the same three-layer blueprint everywhere it appears, scaled up or down to the job each vessel does.
See it move: Scene 1 · Three Tunics
II · One Template, Three Jobs
Every vessel larger than a capillary is built from three tunics. The innermost is the tunica intimaThe innermost layer of a blood vessel, consisting of endothelium and a thin connective tissue layer., lined by a single sheet of endotheliumThe innermost layer of blood vessels, composed of simple squamous epithelial cells, which reduces fr — the smooth, active surface that touches the blood. Around it is the tunica mediaThe middle layer of a blood vessel, composed of smooth muscle and elastic tissue, responsible for va, smooth muscle and elastic tissue that set diameter. Outermost is the tunica externaThe outermost layer of a blood vessel, made of connective tissue, providing support and anchoring., a tough collagenA structural protein in the dermis that provides strength and elasticity. coat that anchors the vessel. Form follows pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange.: arteries build a thick, muscular, elastic media; veins run at low pressure with thin walls and one-way valves; capillaries shrink to a single endothelial layer so exchange can happen across one cell.
See it move: Scene 1 · Three Tunics · Scene 2 · Arteries Under the Microscope · Scene 3 · Veins Under the Microscope · Scene 4 · Capillaries: One Cell Thick
III · The Injured Lining
Stina’s two findings live in these layers, and both trace to the same fault line. The inner lining is a living sensor, glassy and non-stick when healthy, sticky and permeable when inflamed — and a sticky intima is where LDL seeps in and plaque begins. Read the three tunics and you can read either of her findings.
See it move: Scene 5 · Exchange: A Pressure Tug-of-War
3
Watch · explore · think · check
5 scenes. Each one has a short animation or a slide, something to explore, a true/false spot-check of your thinking, and a quick check. Every scene gives you an evidence card for your board.
How to read the scenes
- Animation (dark teal) — a short animated explainer, one idea each
- Slide (dark teal) — a still to study: a micrograph, a diagram or a map
- Explore (purple) — something to push on while you watch
- Game (purple) — a quick challenge
- Think (gold) — reason it out, then spot-check yourself with a few true/false questions; not graded
- Check (gold) — a quick H5P that scores itself
Scene 1 of 5
Three Tunics
Intima, media, externa — every vessel, every time.
Animation · narrated, with captions
Build a Vessel
Module 16 · 16.2 · Opener and Scene 1 · 6 scenes · about 1½ minutes · narrated. Press Play to start; the words appear in the caption box under the picture.
Scene 1
Paused
Keyboard: when the picture has focus, Space plays or pauses, the left/right arrow keys move between scenes, and M mutes or unmutes.
Text description and full narration
Six-scene narrated animation (about 1½ minutes) with captions, built from BioRender cross-section art. The vessel is a round cross-section on the left; labels with leader lines build up in a column on the right as each coat is added.
Scene 1 · Three coats (0:00–0:11)
On screen: A faint outline of a finished vessel appears with the heading “Three coats — in every vessel larger than a capillary”, then fades, leaving only a pale pink lumen containing seven red blood cells. A label reads “Lumen: the open space the blood runs through.”
Narration: Every vessel larger than a capillary is built from the same three coats. So we start with the lumen — the space the blood runs through, the open space.
Scene 2 · Tunica intima (0:11–0:32)
On screen: A thin ring of purple endothelial cells spins into place around the lumen. Labels: “Tunica intima”, “One sheet of endothelium (simple squamous)”, “Continuous with the lining of the heart”, “So smooth it reduces friction”. A thin cream ring appears just outside it: “Sits on a thin cushion of connective tissue.”
Narration: We wrap the lumen in the tunica intima. It’s a single sheet of endothelium, continuous with the lining of the heart, and the simple squamous cells are so smooth that they reduce friction. This sheet sits on a thin cushion of connective tissue.
Scene 3 · Elastic membrane (0:32–0:43)
On screen: A pale blue wavy ring floats in, a little too large, then snaps down onto the intima and glows gold for a moment. Labels: “Internal elastic lamina” and “An elastic membrane: a wavy line.”
Narration: Around that lies an elastic membrane. There’s the internal elastic lamina. Watch it snap into place as a wavy line.
Scene 4 · Tunica media (0:43–0:58)
On screen: A thick pink ring of smooth muscle grows outward around the lamina, with a thin blue ring at its outer edge. Labels: “Tunica media”, “Sheets of smooth muscle and elastin”, “Controls the diameter”, and a bar labelled “diameter” spans the lumen. A gold nerve fiber labelled “Sympathetic nerve” draws in from the upper left and ends on the media in three beads; bright pulses run down it, the wall thickens inward and the lumen, lining and diameter bar all shrink by about a fifth (“Nerves fire → the vessel narrows”).
Narration: Next comes the tunica media. These are sheets of smooth muscle and elastin. This is the coat that controls the diameter. Sympathetic nerves reach it, and when they fire, the vessel narrows.
Scene 5 · Tunica externa (0:58–1:17)
On screen: The vessel relaxes back to full size as a thin blue outer ring wraps around it and short tan strands draw outward from it. Labels: “Tunica externa” and “Tough collagen fibers that anchor the vessel.” A small red vessel grows in from the lower left, branches around inside the outer coat and shows tiny red cross-sections there, with red dots flowing into it. Labels: “Vasa vasorum” and “‘Vessels of the vessels’ feed the outer wall.”
Narration: Finally, the tunica externa: tough collagen fibers that anchor the vessel. Sometimes, in big vessels, it can have tiny vessels of its own, called the vasa vasorum, which literally means “vessels of the vessels,” and that feeds the outer wall.
Scene 6 · Read any vessel (1:17–1:32)
On screen: The finished cross-section shrinks to the left and its labels line up beside it: Tunica externa, Tunica media, Internal elastic lamina, Tunica intima, Lumen. Tunica intima, Tunica media and Tunica externa are highlighted in yellow one at a time. On the right: “Learn the template once. Then ask: which coat is scaled up or down?” with three small examples — an artery (thick media), a vein (thin media, thick externa) and a capillary (intima only).
Narration: Intima, media, externa. Learn the template once, and you can read any vessel on a slide by asking which coat has been scaled up or down for the specific job.
Prefer the full lecture? Blood Vessel Tunics (original 2019 video)
Think · not graded
Your notes say the media is “innervated by sympathetic nerves.” Why would the body want a nerve on a blood vessel?
Spot-check your thinking: true or false?
Check · Single Choice
One question: the three tunics.
Evidence card 1
Add it to your evidence board
Every vessel larger than a capillary shares three coats; the intima is the one sheet of cellsThe basic structural and functional units of life. that touches blood.
Scene 2 of 5
Arteries Under the Microscope
Elastic, muscular, arteriole — thick walls for high pressure.
Slide · a still to study
Elastic and Muscular Arteries, H&E
Many elastic layers in a large artery; a thick, muscular media in a medium-sized one.
Explore
Find the arteriole
Open each marker on a real section A cut or slice of the body or an organ for study. of fat tissue and find the arteriole hiding beside its venule.
Prefer the full lecture? Introduction to Blood Vessels (original 2019 video)
Think · not graded
Elastic arteries “have lots of smooth muscle but can’t vasoconstrict.” What are they for, then?
Spot-check your thinking: true or false?
Check · Mark the Words
Mark the features you’d use to name each artery on a slide.
Evidence card 2
Add it to your evidence board
Arteries build a thick, elastic, muscular media for high pressure; the arteriole is the vessel that sets resistanceThe opposition to airflow in the respiratory tract, influenced by airway diameter..
Scene 3 of 5
Veins Under the Microscope
A frown on a clown.
Game
Artery or vein?
Six microscope fields. Sort each one: artery or vein? Look at the lumen shape and the media before anything else.
Prefer the full lecture? Vein Anatomy (original 2019 video)
Explore
One-way doors
Standing up, the veins at your ankle sit at the bottom of a column of blood more than a meter tall. Only two things move that blood back uphill: your calf muscles squeezing the veins, and the one-way valves inside them. Run the test clinicians use, on two legs.
Run the ankle-pressure test
Leg A is lying flat. Press Stand still to start the test.
Ten years of leaky valves
When the pressure stays high all day, it stretches the thin vein wall. A wider vein pulls its valve cusps apart, so even more blood falls back, and the pressure climbs higher still. Over years, the vein bulges and twists under the skin: a varicose vein.
More likely with long hours of standing, pregnancy, extra weight, age and a family history.
- High pressurein the vein all day
- Wall stretchesthe vein widens
- Cusps can’t meetthe valve leaks more
- More blood falls backso the pressure rises again
- ↻ and round the loop again
Why this matters for Stina
Her chart shows a phlebolith: a small clot that formed in a pelvic vein and later calcified. Clots form most easily where three things meet: slow-moving blood, an injured lining, and blood that is primed to clot. Veins supply the slow flow. Inflammation can supply the other two.
Text description of this activity
A leg drawing shows its veins, with one vein on the lower leg twisted and bulging. A small circle marks the spot shown in the close-up. The close-up shows a section of vein with one valve: in Leg A the two cusps meet in the middle; in Leg B the vein is wider and wavy and the cusps no longer meet. Dark blue dots are blood cells; they drift upward, hold still, or slip back down depending on what the leg is doing, and a red arrow shows the direction of flow. A dark monitor panel shows the pressure in an ankle vein as a number and as a line on a strip chart, with Leg A in mint green and Leg B in amber.
What the test shows (typical values, rounded):
- Lying flat: about 12 mm Hg in either leg.
- Standing still: the pressure climbs to about 90 mm Hg in either leg, because the whole column of blood from the heart down to the foot presses on the ankle veins. Valves cannot lower this on their own.
- Walking, Leg A: each step squeezes the calf veins, the valves above open and the valves below shut, and the pressure falls to about 20 to 25 mm Hg.
- Walking, Leg B: blood falls back through the leaky valves between steps, so the pressure only falls to about 60 mm Hg.
- Stopping, Leg A: the veins refill slowly from the arteries and take more than 20 seconds to reach the standing pressure again. Leg B refills in under 10 seconds, because blood pours back down through the leaky valves. A short refill time is how clinicians spot leaky valves.
Sources: typical venous pressures from NCBI Bookshelf, “Pathophysiology and Principles of Management of Varicose Veins” (Mechanisms of Vascular Disease).
Think · not graded
Veins hold about 65% of the blood. Why would the body keep most of its blood on the low-pressure side?
Spot-check your thinking: true or false?
Check · Fill in the Blanks
Five blanks on what a vein looks like when sectioned.
Evidence card 3
Add it to your evidence board
Veins run at low pressure with thin walls, valves and a big reservoir; her phlebolith is a clot that mineralized in a vein wall.
Scene 4 of 5
Capillaries: One Cell Thick
Continuous, fenestrated, sinusoid.
Animation · narrated, with captions
One Cell Thick
Module 16 · 16.2 · Scene 4 · 5 scenes · about 1¾ minutes · narrated. Press Play to start; the words appear in the caption box under the picture.
Scene 1
Paused
Keyboard: when the picture has focus, Space plays or pauses, the left/right arrow keys move between scenes, and M mutes or unmutes.
Text description and full narration
Five-scene narrated animation (about 1¾ minutes) with captions. Scene 1 shows a capillary in cross-section and lengthwise; from scene 2 on, three capillaries seen lengthwise are stacked on a pale tissue background, each named in a column on the left.
Scene 1 · One cell thick (0:00–0:26)
On screen: A small round vessel in cross-section: a pale lumen ringed by a thin purple layer of endothelial cells. Heading: “The smallest, thinnest vessels.” A faint media and externa appear around it and fade away (“Just a tunica intima — no media, no externa”). Labels with leader lines: “Endothelium: one layer of simple squamous cells”, a dark ring drawn just outside it (“Basement membrane”), and “Lumen: barely wide enough for one red blood cell”, as one red blood cell pops into the lumen and fills it. Below, the same capillary seen lengthwise: two rows of flat endothelial cells with red blood cells moving through in single file. “One cell thick: that’s the point.” Orange O₂ chips rise out through the wall and a blue CO₂ chip drops in: “Exchange happens across one cell.”
Narration: Capillaries are the smallest vessels. They’re also the thinnest. They’re just tunica intima — just. They’re a single layer of endothelium, simple squamous cells, on a basement membrane, with a lumen barely wide enough for one red blood cell. That thinness, though — that’s the point. Exchange happens across one cell.
Scene 2 · Continuous (0:26–0:49)
On screen: The lengthwise capillary moves to the top row and is named “Continuous” (row 1 of 3; heading “Three kinds of capillaries”). Small purple bars appear at every cell border (“Tight junctions”), and gold arrows point at the tiny slits between cells (“Clefts: very small spaces”). Tag: “Skin, muscle.” Then dark bars seal every slit: “Brain: even the clefts are gone — the blood–brain barrier”, tag “Brain: sealed (BBB)”.
Narration: There are three kinds of capillaries. Continuous capillaries have cells joined by tight junctions, with only very small spaces called clefts between them. That’s like skin and muscle. In the brain, even the clefts are gone. That is the very tightly controlled blood–brain barrier.
Scene 3 · Fenestrated (0:49–1:00)
On screen: A second capillary appears in row 2, named “Fenestrated”: small round holes open through the thin parts of its cells (“Pores (fenestrations)”, “Built for absorbing and secreting”). Tag: “Kidney, small intestine.”
Narration: Fenestrated capillaries are riddled with pores. They’re kind of built for absorbing and secreting. The kidney, the small intestine — they have those.
Scene 4 · Sinusoid (1:00–1:27)
On screen: A third, wider capillary appears in row 3, named “Sinusoid”: its cells are spaced apart with large open gaps and its basement membrane is broken (“Large gaps between cells”, “A wide, slow lumen”); red cells drift through slowly. Tag: “Liver, bone marrow, spleen.” A Kupffer cell sits on the wall; a green rod-shaped bacterium drifts along the lumen until the Kupffer cell catches and swallows it.
Narration: Sinusoid capillaries — they’re huge, and they’re leaky. They have enormous gaps between the cells, almost as big as red blood cells, and a wide, slow lumen — almost not even flow, but a pulsating movement. That’s the liver, bone marrow, your spleen. In the liver, the flow is slow enough for cells to catch bacteria as they pass.
Scene 5 · Matched to the job (1:27–1:49)
On screen: Heading changes to “Same coat, three degrees of leakiness.” A legend along the bottom introduces glucose (a gold hexagon), a protein (a purple blob) and a red blood cell, and one of each sits in every capillary. The three glucose molecules slip out through a cleft, a pore and a gap (“✓ glucose gets out” in every row). The protein bounces off the continuous and fenestrated walls (“✗ protein stays in”) but leaves through the sinusoid’s gap (“✓ protein gets out”). Each red blood cell bumps the wall and stays (“✗ red cell stays in”).
Narration: Watch a glucose molecule, a protein, and a red blood cell try each one. Glucose slips through all three. Protein gets out only through the sinusoid’s gaps, and the red blood cell stays in the blood — absolutely. Same coat, three degrees of leakiness, matched to the job that they have.
Prefer the full lecture? Capillary Anatomy (original 2019 video)
Explore
What gets through?
Same capillary, two different days: a quiet day, and a flare, when the lining is inflamed. Look through the window, predict what leaves the blood each day, then check yourself and watch it happen.
Top: blood. Middle: one row of endothelial cells on a thin basement membrane. Bottom: tissue.
Your predictions
For each passenger, choose Stays in or Gets out of the blood, on a quiet day and during a flare. Nothing is recorded.
Why this matters for Stina
An FMF attack is a flare like this one, but in the lining of the chest, heart or belly, and with no infection to fight. Neutrophils pour out of the capillaries, protein-rich fluid collects, and the lining hurts with every breath or heartbeat.
That is the pleurisy she had at 16 and the small effusion on her echo in The Heart. Decades of flares like these are the injured lining this chapter is about.
Text description of this activity
The window shows a close-up of a capillary wall. Blood fills the top, tissue fills the bottom, and between them lies one row of flat endothelial cells on a thin basement membrane. Five passengers ride in the blood: water, glucose, albumin (a large protein), a neutrophil (a white blood cell) and a red blood cell.
Quiet day: the endothelial cells are joined tightly, with only narrow clefts between them. Water and glucose slip out through the clefts. Albumin is too large for the clefts and stays in the blood. The neutrophil tumbles past the slick lining and stays in. The red blood cell stays in.
Flare: inflammatory signals make the endothelial cells round up and pull apart, opening gaps, and their surface becomes sticky. Water and glucose pour out. Albumin leaks out through the gaps and drags water with it, so the tissue swells. The neutrophil rolls along the sticky lining, grabs hold, and squeezes out between the cells into the tissue. The red blood cell still stays in; red cells escape only when a vessel is torn.
Think · not graded
Sinusoids are “very leaky.” Which organs would you expect to have them, and why?
Spot-check your thinking: true or false?
Check · Fill in the Blanks
Name the three capillary types.
Evidence card 4
Add it to your evidence board
Capillaries are a single endothelial layer built for exchange; the endothelium is the whole wall.
Scene 5 of 5
Exchange: A Pressure Tug-of-War
Hydrostatic out, oncotic in.
Animation · narrated, with captions
Starling’s Balance
Module 16 · 16.2 · Scene 5 · 6 scenes · about 1½ minutes · narrated. Press Play to start; the words appear in the caption box under the picture.
Scene 1
Paused
Keyboard: when the picture has focus, Space plays or pauses, the left/right arrow keys move between scenes, and M mutes or unmutes.
Text description and full narration
Six-scene narrated animation (about 1½ minutes) with captions. A capillary made of flat endothelial cells runs left to right across a pale green band of tissue with a few tissue cells; red blood cells flow through it from the arterial end (left) to the venous end (right). Summary lines build up along the bottom.
Scene 1 · A tug-of-war (0:00–0:12)
On screen: A capillary crosses the screen between tissue cells, labelled “Capillary” and “Tissue fluid”. Heading: “A tug-of-war across the capillary wall.” Labels: “← Arterial end” (left, red) and “Venous end →” (right, blue); the blood in the lumen shades from red on the left to purple on the right.
Narration: Fluid crosses the capillary wall kind of like in a tug-of-war. The arterial end of the capillary bed is on the left, and the venous end is on the right.
Scene 2 · The push (0:12–0:24)
On screen: A large red arrow pointing outward appears above the arterial end, labelled “35”. Four blue water droplets squeeze out through the clefts between the wall cells into the tissue above and below. Bottom line: “Push: blood pressure inside the capillary, about 35 mm Hg.”
Narration: On the arterial end, blood pressure inside the capillary — about 35 millimeters of mercury — pushes water out through the clefts and into the tissue.
Scene 3 · The pull (0:24–0:43)
On screen: A purple arrow pointing inward appears beside the red one, and a second purple inward arrow at the venous end, each labelled “25”. Small purple albumin particles now flow inside the capillary with the blood cells. Bottom line: “Pull: oncotic pressure of plasma proteins (mostly albumin), about 25 mm Hg.”
Narration: Pulling the other way is the oncotic pressure, or the colloid osmotic pressure, of the plasma proteins. It’s mostly albumin, so it stays inside the vessel, and it draws water back toward it at roughly 25.
Scene 4 · Push wins, then pull wins (0:43–0:58)
On screen: Two more droplets leave at the arterial end. A copy of the red push arrow travels along the capillary to the venous end, shrinking as its number counts down from 35 to 15. At the venous end three droplets in the tissue are drawn back in through the clefts. Bottom lines: “Arterial end: push 35 > pull 25, so fluid leaves” and “Venous end: push 15 < pull 25, so most of the fluid returns.”
Narration: At the arterial end, the push wins, and fluid leaves. As the blood moves along the capillary, its pressure falls to about 15. The pull now wins, and most of the fluid starts to return.
Scene 5 · The lymphatic (0:58–1:04)
On screen: A pale yellow, blind-ended lymphatic vessel appears in the tissue below the venous end (“Lymphatic vessel”), and three of the leftover droplets drift into it. Bottom line: “What does not return is collected by lymphatic vessels.”
Narration: What does not return is collected by lymphatic vessels.
Scene 6 · Edema (1:04–1:28)
On screen: Heading changes to “Take the albumin away.” The purple albumin particles fade out of the capillary and both purple pull arrows and their 25s disappear; the red push arrows stay. Many droplets leave through clefts all along the capillary and stay in the tissue; the green tissue band swells taller, pushing the tissue cells and the lymphatic outward, and a red “Edema” label pops up. Bottom lines: “No albumin: nothing pulls the water back, but the push is unchanged”, “Fluid leaves and stays in the tissue: edema”, “Coming up in the kidney module: Stina begins losing albumin.”
Narration: All right, so now take the albumin away, and the push is unchanged. But nothing pulls the water back in. There’s no pull. Fluid leaves and stays in the tissues. It’s called edema. It’s the seed of the story this course returns to in the kidney module, when Stina begins losing her albumin.
Prefer the full lecture? Filtration and Reabsorption in Capillary Beds (original 2019 video)
Explore
The swelling clinic
Six patients, and every one has tissue fluid that is out of balance, each for a different reason. Pick a patient and read the chart. Then set the four controls to match what that body is doing, and press Test. The capillary bed updates as you go.
The weak heart
The four controls
Text description of this activity
The picture is a capillary bed seen from above. A red arteriole enters on the left, branches into a network of capillaries that shift from red to purple to blue, and joins a blue venule on the right. The bed sits in pale green tissue. A yellow-green lymphatic vessel runs along the bottom. Arrows at the arterial and venous ends show whether fluid is leaving the blood (pointing outward, red) or returning (pointing inward, blue), and blue droplets in the tissue show how much fluid is building up. Every number is also written out below the picture.
How the numbers work: the push is blood pressure in the capillary, 35 mm Hg at the arterial end and 15 at the venous end when healthy. The pull is plasma albumin (25) minus any protein that has leaked into the tissue (1 when the wall is tight). When the push is bigger, fluid leaves; when the pull is bigger, fluid returns. Lymphatic vessels carry off the small leftover.
- Healthy: arterial end 35 − 24 = 11 out; venous end 15 − 24 = 9 back in. Lymph handles the small leftover, and the tissue stays balanced.
- High capillary pressure (45 → 25): fluid leaves along the whole capillary. Swelling.
- Low pressure (25 → 10): the pull wins almost everywhere, so fluid returns to the blood and the tissue gets drier.
- Low albumin (15): the pull weakens and fluid stays in the tissue. Swelling.
- Leaky wall: albumin escapes into the tissue (pull from outside rises to 10), the net pull shrinks, and fluid floods out. Swelling.
- Lymph blocked: the pressures are normal, but the small leftover cannot drain. Slow swelling.
Think · not graded
This chapter plants a seed for the kidney module: what happens to this balance when albuminA plasma protein that helps maintain osmotic pressure and transport substances. leaks out of the body?
Spot-check your thinking: true or false?
Check · Drag the Words
Complete Starling’s balance, end to end.
Evidence card 5
Add it to your evidence board
Exchange across the capillary is a balance of hydrostatic and oncotic pressure — a balance the case returns to later.
4
Your evidence board
Every scene gave you an evidence card, and the chart adds more. Drag each card to the column it supports: The inner lining, Neither on its own, or Media or externa. Some cards can honestly go in more than one place — that’s allowed, and the feedback tells you which cards decide the case.
5
Your verdict
Time to decide. Look back at your bet, then build your verdict from statements that hold up — no writing needed.
Look back at your prediction
Her calcium is in an artery wall and her clot is in a vein wall. The layer where vessel disease begins is…
Open the one you chose at the top. Does the evidence support it, refute it, or revise it?
If you bet: The outer coat — the tough collagen that anchors the vessel
The externa is the thickest coat in a vein, but it never touches blood. The scenes showed that disease starts at the one layer that does: the intima.
If you bet: The middle coat — the smooth muscle that sets diameter
The media sets diameter, and it matters for pressure — but plaque doesn’t begin there. It begins when the intima is injured and LDL gets in underneath it.
If you bet: The inner lining — the one sheet of cells that touches blood
Your bet held. Both of her findings sit in a wall, and in both the story starts at the lining: the one sheet of cells that senses the blood.
Build your verdict · no writing
Choose the statement that holds in each set. The ones you keep become your argument.
6
The finding
Sign · disease in the vessel wall (intima)
Vascular Findings Rooted in the Vessel Wall
Stina’s coronary calcium sits within an artery’s wall and her phlebolith within a vein’s wall — both are diseases of the tunics, not blockages sitting loose in the lumen. Every vessel shares three coats — intima (sensing lining), media (muscular middle), externa (anchor) — and the intima is where injury, inflammation and plaque all begin. Chart entry: her vascular disease is located in the wall itself, at the inflamed intimal lining.
Next · Chapter 3
Pressure and Flow
Her blood pressure is a textbook 118/74. High pressure is the classic way to batter a wall — and she doesn’t have it. Find out what pressure does and doesn’t protect against.
Reliable information on rare diseases
NORD · NIH GARD · Orphanet · MedlinePlus Genetics: FMF · FMF & AID Global Association · Autoinflammatory Alliance · Global Genes · Amyloidosis Foundation
Stina has one rare disease. In the United States, about 1 in 10 people live with one of the more than 7,000 known rare diseases. These organizations are where patients, families and clinicians go for trustworthy information.
Hop to:
← Familial Mediterranean Fever — case home
All pages for Module 16 — Blood Vessels
16.0 Module Overview
16.1 Vessels Aging Too Fast
16.2 Three Layers, Three Vessels
16.3 Pressure and Flow
16.4 The Body’s Highways
16.5 When Walls Go Bad: Atherosclerosis
16.6 Cholesterol, Calcium & Statins
16.7 Premature Vascular Aging
16.8 Conclusion and Assessment
16.9 Evidence Behind the Case
All Modules
- Anatomical Language, Membranes & Homeostasis
- Just Enough Chemistry
- The Cell & Its Transport
- Making Cells & Proteins
- The Integumentary System
- The Skeletal System
- The Muscular System
- Nervous Tissue & the Senses
- The Spinal Cord
- The Brain & the Blood–Brain Barrier
- The Autonomic Nervous System
- Special Senses (in developmentThe process of growth and differentiation.)
- The Endocrine System
- Blood
- The Heart
- Blood Vessels
- The Digestive System
- The Respiratory System
- The Urinary System
- Fluids, Electrolytes & Acid–Base Balance
- The Reproductive System
- The Immune System
List of terms
- arteries
- veins
- capillaries
- basic
- anatomy
- physiology
- tunica intima
- endothelium
- tunica media
- tunica externa
- collagen
- pressure
- cells
- section
- resistance
- lumen
- albumin
- development