Artery, Vein and Capillary, Hepatic Portal System and Lymph (ICSE Class 10 Biology)
Updated 16 October 2026 · Fact-checked
Arteries carry blood away from the heart under high pressure, so they have thick, muscular, elastic walls and a narrow lumen. Veins return blood at low pressure, with thin walls, a wide lumen and valves. Capillaries, one cell thick, link the two and exchange materials. Leaked tissue fluid returns to blood as lymph.
Compare the wall and lumen: the artery has a thick wall and narrow lumen, the vein a thin wall with valves, and the capillary a wall one cell thick.
Illustration drawn for QuestionBuddy.
Understand Artery, Vein and Capillary, and the Lymphatic System
Three kinds of vessels, three jobs. Structure follows function: the vessel's wall, lumen and valves match the pressure of the blood inside and what the vessel must do.
| Feature | Artery | Vein | Capillary |
|---|---|---|---|
| Direction | away from the heart | towards the heart | arterioles to venules |
| Wall | thick, with much muscle and elastic tissue | thin, less muscle and elastic tissue | single layer of flat cells (endothelium) |
| Lumen | narrow | wide | very narrow, about one RBC wide |
| Valves | absent (except semilunar valves at the bases of the aorta and pulmonary artery) | present at intervals | absent |
| Pressure and flow | high, in spurts (pulse) | low, smooth | low, very slow |
| Blood | oxygenated (except pulmonary artery) | deoxygenated (except pulmonary veins) | gives O₂ and food; collects CO₂ and wastes |
| Position | usually deep | often near the surface | in every tissue |
Why each structure suits its job.
- Artery: thick, elastic walls stretch with each spurt and recoil, withstanding high pressure and keeping blood moving; this stretch is felt as the pulse.
- Vein: low pressure needs no thick wall; a wide lumen offers little resistance; valves stop backflow, and squeezing by surrounding skeletal muscles pushes blood up towards the heart.
- Capillary: a one-cell-thick wall and slow flow allow exchange of oxygen, food, CO₂ and wastes with cells; WBCs squeeze out through these walls (diapedesis).
Vessels of the liver and kidney (names required by the syllabus).
| Organ | In | Out |
|---|---|---|
| Liver | hepatic artery (oxygenated); hepatic portal vein (food-rich, from the gut) | hepatic vein → inferior vena cava |
| Kidney | renal artery (from the aorta) | renal vein → inferior vena cava |
Hepatic portal system and its significance. A portal vein starts in capillaries of one organ and ends in capillaries of another. The hepatic portal vein collects blood from the stomach and intestines and takes it to the liver, not straight to the heart. Significance: the liver regulates the amount of digested food reaching the body (stores excess glucose as glycogen) and removes or detoxifies harmful substances absorbed from the gut. Sequence: stomach/intestine → hepatic portal vein → liver → hepatic vein → inferior vena cava → right atrium.
Tissue fluid and lymph (brief).
- At the arterial end of capillaries, part of the plasma leaks out into the spaces between cells as tissue fluid (no RBCs, few proteins). It bathes cells, delivering food and oxygen and taking away wastes.
- Most returns to the capillaries; the rest enters blind-ended lymph capillaries and is now called lymph: colourless, rich in lymphocytes.
- Lymph flows one way through lymph vessels and lymph nodes (which filter germs) and joins the blood in veins near the neck. Lymph vessels of the intestine (lacteals) absorb fats.
Lymphatic organs (brief).
- Spleen: largest lymphatic organ, upper left abdomen; destroys old RBCs, makes lymphocytes, stores blood.
- Tonsils: in the throat; trap and destroy germs entering by the mouth and nose.
Flow chart. Heart → artery → arteriole → capillary (exchange; tissue fluid leaks out) → venule → vein → heart; tissue fluid → lymph capillary → lymph vessel → lymph node → vein near the neck.
Draw-and-label checklist: T.S. of artery and vein. Draw side by side. Artery: round outline, thick middle muscle layer, narrow round lumen; label outer layer, muscular and elastic layer, endothelium, lumen. Vein: flattened or irregular outline, thin muscle layer, wide lumen; same labels plus a valve in an L.S. sketch. Capillary: a tube with one layer of flat cells, an RBC in single file inside.
Artery, Vein and Capillary, and the Lymphatic System: key facts
- Artery, vein, capillary
Artery thick muscular elastic wall, narrow lumen, no valves, high pressure Vein thin wall, wide lumen, valves, low pressure Capillary one-cell wall, exchange - Always name the part: wall, lumen, valves.
- Liver and kidney vessels
Liver in hepatic artery, hepatic portal vein Liver out hepatic vein Kidney in renal artery Kidney out renal vein - Both outflows join the inferior vena cava.
- Tissue fluid and lymph
Tissue fluid plasma leaked from capillaries, bathes cells Lymph tissue fluid in lymph vessels, many lymphocytes Spleen destroys old RBCs Tonsils trap germs - Lymph flows one way, back to the blood.
How to answer Artery, Vein and Capillary, and the Lymphatic System questions
ICSE asks structural differences between an artery and a vein, the function of capillaries, the order of blood flow through the hepatic portal system, the vessels of the liver and kidney, and brief roles of lymph, spleen and tonsils.
- 1For differences, compare the same feature each time: wall, lumen, valves.
- 2Do not give functions when 'structural' differences are asked.
- 3For the hepatic portal sequence, start at the gut and end at the inferior vena cava.
- 4For a vessel identity, check direction (to or from the organ) and oxygen content.
- 5For lymph, give source (tissue fluid), content (lymphocytes) and destination (veins).
Artery, Vein and Capillary, and the Lymphatic System in real life
The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.
Blood test from a vein
Suppose at a pathology lab the technician ties a band around your upper arm and takes blood from a vein at the elbow, not from an artery.
Why a vein, and why the band?
Try it first, then show the solutionSolution
- Veins lie near the surface and have thin walls, so the needle enters easily.
- Blood pressure in veins is low, so bleeding stops quickly afterwards.
- The band blocks the return of blood to the heart, so the veins below it swell and stand out.
- Arteries lie deeper and carry blood at high pressure, so they are avoided.
Answer: Veins are surface, thin-walled and low-pressure; the band makes them fill and bulge.
Memory hook: Veins are visible, arteries are away (deep).
Swollen glands in a sore throat
Suppose during a throat infection you feel tender lumps under your jaw, and the doctor says your tonsils and lymph nodes are fighting germs.
Explain the swelling.
Try it first, then show the solutionSolution
- Germs entering by the mouth and nose are trapped by the tonsils.
- Lymph from the area drains through nearby lymph nodes, which filter germs.
- Lymphocytes multiply in these nodes to make antibodies.
- The extra cells and fluid make the nodes swell and become tender.
Answer: Tonsils and lymph nodes trap germs and fill with multiplying lymphocytes, so they swell.
Memory hook: Swollen nodes = busy soldiers.
Tricks to remember Artery, Vein and Capillary, and the Lymphatic System
Short memory aids. Say each one aloud once, then use it on a question the same day.
Artery = Armoured
Arteries are armoured with thick walls for high pressure; veins have valves.
Use it when: Structural differences.
Gut, Portal, Liver, Hepatic, Cava
'Good People Love Healthy Cities': gut → portal vein → liver → hepatic vein → vena cava.
Use it when: Ordering the hepatic portal route.
Spleen = RBC graveyard
Old red cells go to the spleen to be broken down.
Use it when: Function of the spleen.
Artery, Vein and Capillary, and the Lymphatic System: solved examples
Ordered from board level to HOTS. Try each one before you open the solution.
Example 1: Exchange vessels · 1 mark · MCQBoard level
Exchange of oxygen and food between blood and body cells takes place through the walls of:
(a) arteries (b) veins (c) capillaries (d) lymph vessels
Try it first, then show the solutionSolution
- Only capillaries have walls one cell thick.
Answer: (c) capillaries.
Example 2: Pulse in an artery, not a vein · 2 marks · Short answerBoard level
A nurse feels a pulse at the wrist but cannot feel one in the veins visible on the back of the hand. Explain this in terms of the structure of the vessels and the pressure of blood in them.
Try it first, then show the solutionSolution
- Blood enters arteries in spurts at high pressure with each heartbeat; the thick, elastic artery wall stretches and recoils, which is felt as the pulse (1 mark).
- Veins carry blood at low, steady pressure and have thin walls with little elastic tissue, so no pulse is felt (1 mark).
Answer: Elastic arteries stretch and recoil with each high-pressure spurt (pulse); thin-walled veins carry low, steady pressure, so there is no pulse.
Example 3: Glucose before and after the liver · 3 marks · Short answerHarder board level
After a meal, blood in the hepatic portal vein is compared with blood in the hepatic vein. (a) Which has more glucose, and why? (b) Which of these two vessels carries blood into the liver and which carries it out? (c) Into which large vein does the hepatic vein drain?
Try it first, then show the solutionSolution
- (a) The hepatic portal vein: it brings glucose absorbed from the intestine, and the liver stores the excess as glycogen before the blood leaves (1 mark).
- (b) Hepatic portal vein into the liver; hepatic vein out of it (1 mark).
- (c) The inferior vena cava (1 mark).
Answer: (a) Hepatic portal vein, because the liver stores excess glucose as glycogen. (b) Portal vein in, hepatic vein out. (c) Inferior vena cava.
Example 4: Lymph versus blood · 2 marks · Short answerHarder board level
Give two differences between lymph and blood.
Try it first, then show the solutionSolution
- Lymph has no RBCs and is colourless; blood has RBCs and is red (1 mark).
- Lymph has fewer proteins and many lymphocytes, and flows one way in lymph vessels; blood flows in a closed circuit through the heart (1 mark).
Answer: No RBCs, colourless; fewer proteins, one-way flow in lymph vessels.
Example 5: Varicose veins · 3 marks · Short answerHOTS / competency
Suppose a traffic policeman who stands for long hours develops swollen, twisted veins in his legs. Explain, using the structure of veins, why standing still makes this worse and why walking helps.
Try it first, then show the solutionSolution
- Blood in leg veins must rise against gravity at low pressure; valves stop it falling back (1 mark).
- Standing still, muscles do not squeeze the veins, blood pools, and the weak valves leak, so the thin walls stretch (1 mark).
- Walking makes calf muscles contract and squeeze the veins, pushing blood upwards past the valves (1 mark).
Answer: Pooling stretches thin walls when valves fail; muscle squeezing during walking pushes blood up.
Example 6: Two kidney vessels · 3 marks · Case-basedHOTS / competency
Suppose a sample from the renal artery and one from the renal vein of the same person are compared. (a) Which has more urea? (b) Which has more oxygen? (c) Into which large vessel does the renal vein drain?
Try it first, then show the solutionSolution
- (a) Renal artery; the kidney removes urea before blood leaves (1 mark).
- (b) Renal artery; kidney cells use oxygen (1 mark).
- (c) Inferior vena cava (1 mark).
Answer: (a) Renal artery. (b) Renal artery. (c) Inferior vena cava.
Where students lose marks in Artery, Vein and Capillary, and the Lymphatic System
The slips examiners see most often, and what to write instead.
Mistake: 'Thick' and 'thin' with nothing named
CISCE examiners' comments (2024): for structural differences, candidates said arteries are thick and veins thin without specifying wall or lumen, or gave functions instead of structural differences.
Do this: Artery: thick muscular wall, narrow lumen; vein: thin wall, wide lumen, valves.
Usually costs: 1-2 marks.
Mistake: Hepatic vein and hepatic portal vein swapped
CISCE examiners' comments (2025): in a sequence question, candidates interchanged the hepatic vein and hepatic portal vein, or placed the portal vein before the stomach.
Do this: Gut first, portal vein into the liver, hepatic vein out of it.
Usually costs: 1 mark.
Mistake: 'All arteries carry oxygenated blood'
The pulmonary artery carries deoxygenated blood; vessels are named by direction, not by oxygen content.
Do this: Artery = away from the heart.
Usually costs: 1 mark.
Exam tips
- Compare wall, lumen and valves for structural differences.
- Capillaries: one cell thick, exchange.
- Gut → hepatic portal vein → liver → hepatic vein → inferior vena cava.
- Lymph = tissue fluid in lymph vessels, rich in lymphocytes.
Practice questions on Artery, Vein and Capillary, and the Lymphatic System
Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.
Q1 · 1 mark · MCQBoard level
The vessel that carries blood from the intestine to the liver is the:
(a) hepatic artery (b) hepatic vein (c) hepatic portal vein (d) renal veinHint
Portal = from one organ to another.
Answer
(c) hepatic portal vein.
Q2 · 1 mark · Very short answerBoard level
Name the largest lymphatic organ.
Hint
Upper left abdomen.
Answer
Spleen.
Q3 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Arteries have thick, muscular and elastic walls.
Reason (R): Blood is pumped into arteries in spurts at high pressure.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation of (A).Hint
Wall matches pressure.
Answer
(c).
Q4 · 2 marks · Short answerHarder board level
A muscle working hard has many more open capillaries than the same muscle at rest. Explain why this is useful.
Hint
Surface and distance.
Answer
More open capillaries give a larger surface for exchange and bring blood closer to every muscle cell, so more oxygen and glucose are delivered and more CO₂ and wastes are removed.
Q5 · 2 marks · Short answerHarder board level
What is tissue fluid? State its role.
Hint
Leaked plasma.
Answer
Part of the plasma that leaks out of capillaries into the spaces between cells; it bathes the cells, supplying food and oxygen and removing wastes.
Q6 · 2 marks · Short answerHarder board level
Name the vessels that (a) bring oxygenated blood to the liver, (b) take blood away from the kidney.
Hint
Hepatic and renal.
Answer
(a) Hepatic artery (b) Renal vein.
Q7 · 2 marks · Short answerHarder board level
State the functions of the tonsils and the spleen.
Hint
Germs; old RBCs.
Answer
Tonsils trap and destroy germs entering through the mouth and nose. The spleen destroys old RBCs, makes lymphocytes and stores blood.
Q8 · 3 marks · Case-basedHOTS / competency
Read and answer.
Suppose a patient's blood pressure is 120/80 mm Hg in the arm artery, while pressure in a large vein near the heart is close to zero.
(a) What is the difference between the two artery readings? (1)
(b) Which feature of the artery wall allows it to cope with the higher figure? (1)
(c) How is blood moved back to the heart despite the low venous pressure? Give two ways. (1)Hint
Muscle and valves.
Answer
(a) 120 − 80 = 40 mm Hg. (b) A thick, muscular and elastic wall. (c) Valves prevent backflow, and contraction of surrounding skeletal muscles squeezes the veins (breathing movements also help).
Test your recall
Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.
1.Which vessels have valves along their length?Show answer
Veins.
2.Which vessel takes blood from the kidney?Show answer
Renal vein.
3.What is lymph?Show answer
Tissue fluid that has entered lymph vessels; colourless, with many lymphocytes.
4.Which organ destroys old RBCs?Show answer
Spleen.
5.What does a portal vein do?Show answer
Carries blood from the capillaries of one organ to the capillaries of another.
Artery, Vein and Capillary, and the Lymphatic System: frequently asked questions
Why are veins blue under the skin?
Blood in veins is dark red; skin and light scattering make the vessels look bluish. Venous blood is never blue.
Do I need all the named arteries of the body?
No. Only the main vessels entering and leaving the heart, liver and kidney.
Is lymph the same as plasma?
It comes from plasma but has fewer proteins, no RBCs and many lymphocytes.
Why does the liver get two blood supplies?
The hepatic artery brings oxygen; the hepatic portal vein brings digested food and absorbed substances for processing.