🔴 1. Circulatory System in Humans — Blood Transportation
The circulatory system is the body's transport network. It carries oxygen,
nutrients, hormones, and waste products through the blood to all body cells and removes waste products.
Main Components of the Circulatory System:
- 🫀 Heart — the pump (about the size of your fist, located in the chest cavity)
- 🔴 Blood — the transport fluid (5–6 litres in an adult human)
- 🩸 Blood vessels:
- Arteries — carry blood away from heart; thick walls, high
pressure, carry oxygenated blood (except pulmonary artery)
- Veins — carry blood to heart; thin walls, low pressure, carry
deoxygenated blood (except pulmonary vein)
- Capillaries — microscopic vessels; connect arteries to veins; one cell
thick → allow exchange of O₂, nutrients, CO₂, waste between blood and cells
Flowchart: Path of Blood in Human Body (Double Circulation)
🫀 Right side of Heart (deoxygenated blood received)
⬇
Pulmonary Artery → Lungs (CO₂ released, O₂ absorbed)
⬇
Pulmonary Vein → Left side of Heart (oxygenated
blood received)
⬇
Aorta → All body arteries → Capillaries (O₂ &
nutrients delivered to all cells)
⬇
Body veins (CO₂ & waste collected) → Vena Cava →
Right side of Heart
This circular pathway repeats continuously — called the circulation
📸 AI Image Prompt
A detailed labeled diagram of the human heart and circulatory system showing double
circulation. The heart is shown in the center, divided into 4 chambers: Right Atrium (RA), Right
Ventricle (RV), Left Atrium (LA), Left Ventricle (LV) — all labeled. Two distinct circulation loops in
different colors: (1) "Pulmonary Circulation" in blue — from the right side of heart → pulmonary artery
(deoxygenated, shown in blue) → lungs (CO₂ released, O₂ absorbed, shown with tiny bubbles) → pulmonary
vein (oxygenated, shown in red) → left side of heart. (2) "Systemic Circulation" in red — from left side
of heart → aorta → body arteries (red, oxygenated) → capillaries throughout body (red turning blue as O₂
is delivered) → body veins (blue, deoxygenated) → right side of heart. Arrows show direction of blood
flow. Bold labels on all vessels and chambers. Educational medical diagram style, red and blue color
coding, white background, clear and accurate.
Fig. 7.1 — Double circulation in humans (pulmonary + systemic)
🩸 2. Components of Blood
| Component |
What it looks like |
Main Function |
| Red Blood Cells (RBCs) |
Disc-shaped, no nucleus, red (contain haemoglobin) |
Carry oxygen using haemoglobin (O₂ + Hb → oxyhaemoglobin) |
| White Blood Cells (WBCs) |
Various shapes, have nucleus, colourless |
Fight infections; produce antibodies; the body's defence army |
| Platelets |
Tiny fragments |
Clotting of blood (form a plug to stop bleeding when a blood vessel is cut) |
| Plasma |
Pale yellow liquid (~55% of blood volume) |
Transports dissolved nutrients, CO₂, hormones, waste products, antibodies |
A healthy heart beats about 72 times per minute (at rest). "Lub-dub" are the two sounds of
one heartbeat (valves closing). During exercise, heart rate increases to deliver more O₂ to muscles. A
device called a stethoscope is used to hear heartbeats.
🌿 3. Transportation in Plants
Plants also have a transport system but it uses two separate tubes instead of a pump:
XYLEM 💧
Carries water + minerals from roots
Direction: upward only (roots → leaves)
Force: root pressure + transpiration pull
One-way transport (no pump needed)
PHLOEM 🍬
Carries food (sucrose/glucose)
Direction: both up and down (leaves → all plant parts)
From leaves → roots, fruits, seeds, growing buds
This transport is called translocation
Transpiration — Water Loss from Leaves
Transpiration = evaporation of water from leaves through stomata. This water
loss creates a "pull" (negative pressure) that draws water upward through the xylem from roots. This is
called transpiration pull — the main force that moves water up tall trees!
Advantages of Transpiration: Cools the plant; helps absorb minerals from soil; creates
water circulation in plants
💧 4. Excretion in Humans — Waste Removal
- The kidneys filter blood and remove waste + excess water as urine
(contains urea, uric acid, salts, water)
- Urine flows through ureters → urinary bladder (stored) → excreted through urethra
- Sweat glands in skin also remove some waste (urea, salts) through sweat
- Lungs remove CO₂ via exhalation
- Liver converts toxic ammonia into less-toxic urea (which kidneys then remove)
📝 5. Quick Revision
- Arteries: carry blood away from heart (oxygenated). Veins: carry
blood to heart (deoxygenated). Capillaries: exchange site
- Heart rate = ~72 beats/minute. Stethoscope hears "lub-dub" sounds
- Blood = RBCs (O₂ transport, haemoglobin) + WBCs (fight infection) + Platelets (clotting) + Plasma
(nutrients)
- Xylem = water + minerals, upward only. Phloem = food (sucrose),
upward + downward (translocation)
- Transpiration = water evaporation from stomata → creates pull → water moves upward
through xylem
- Kidneys filter blood → urine (water + urea + salts). Lungs excrete CO₂. Skin excretes sweat
