Quick Revision Notes & Formula Sheet

Class 7 Science: Transportation in Animals and Plants

MP Board Education

The circulatory system is responsible for the transport of oxygen, nutrients, waste products, and other substances throughout the body.

Blood (रक्त): A fluid that flows in blood vessels. It transports substances like digested food from the small intestine to the other parts of the body.
Components of Blood:
1. Plasma (प्लाज्मा): The liquid part of blood.
2. Red Blood Cells / RBC (लाल रक्त कोशिकाएं): Contain a red pigment called haemoglobin (हीमोग्लोबिन) which binds with oxygen and transports it to all the parts of the body.
3. White Blood Cells / WBC (श्वेत रक्त कोशिकाएं): Fight against germs that enter our body.
4. Platelets (प्लेटलेट्स): Help in the clotting of blood (रक्त का थक्का जमना) to prevent excessive bleeding when injured.

Normal Heart Rate: 72 to 80 beats per minute (असामान्य रूप से आराम करते समय हृदय स्पंदन).
Normal Blood Pressure (Human): Roughly 120/80 mmHg (Systolic/Diastolic).
Pulse Rate: The thumping felt due to the throbbing of blood in the arteries is equal to the number of heart beats per minute.

There are three main types of blood vessels in the human body:

Arteries (धमनियाँ):
- Carry oxygen-rich blood (शुद्ध रक्त) from the heart to all parts of the body.
- Have thick, elastic walls because the blood flows at high pressure.
- Exception: Pulmonary artery carries carbon dioxide-rich blood from the heart to the lungs.
Veins (शिराएँ):
- Carry carbon-rich blood (अशुद्ध रक्त) from all parts of the body back to the heart.
- Have thin walls and valves to ensure blood flows only towards the heart.
- Exception: Pulmonary vein carries oxygen-rich blood from the lungs to the heart.
Capillaries (केशिकाएँ):
- Extremely thin blood vessels that join arteries to veins. Exchange of substances takes place through them.

Definition: The heart is an organ that beats continuously to act as a pump for the transport of blood.
Location: Located in the chest cavity with its tip slightly tilted towards the left.
Chambers of the Heart: The heart is divided into four chambers to prevent mixing of oxygen-rich and carbon dioxide-rich blood:
- Upper chambers: Right Atrium and Left Atrium (दायाँ और बायाँ अलिंद).
- Lower chambers: Right Ventricle and Left Ventricle (दायाँ और बायाँ निलय).
Heartbeat: The walls of the chambers made of muscles contract and relax rhythmically. This rhythmic contraction followed by its relaxation constitutes a heartbeat.

Excretion (उत्सर्जन): The process of removal of wastes produced in the cells of the living organisms.
Excretory System in Humans:
- Consists of a pair of kidneys (वृक्क), a pair of ureters (मूत्रवाहिनी), a urinary bladder (मूत्राशय), and a urethra (मूत्रमार्ग).
- Kidneys: Filter the blood to remove waste products. The filtered waste is dissolved in water and removed as urine (मूत्र).
Excretory Products based on Animals:
- Humans/Mammals: Excrete Urea (यूरिया).
- Fish/Aquatic animals: Excrete Ammonia (अमोनिया) which directly dissolves in water.
- Birds, Insects, Lizards: Excrete a semi-solid, white coloured compound called Uric Acid (यूरिक अम्ल).
Sweat (पसीना): Contains water and salts to help cool the body and remove excess waste.

Plants absorb water and minerals from the soil and transport them to the leaves, which prepare food using sunlight (photosynthesis).

Vascular Tissues (संवहनीय ऊतक): Plants have pipe-like vessels to transport substances. There are two types:
1. Xylem (जाइलम):
  - Transports water and minerals (जल और खनिज लवण) from the roots to the leaves and other parts of the plant.
  - Forms a continuous network of channels.
2. Phloem (फ्लोएम):
  - Transports food (भोजन/खाद्य पदार्थ) prepared by the leaves to all other parts of the plant.
Transpiration (वाष्पोसर्जन):
- The process by which plants lose water in the form of water vapour through tiny pores called stomata (रंध्र) present on the leaves.
- Functions:
  - Creates a suction pull that draws water up from the roots to great heights.
  - Helps in cooling the plant.