Notes - 8th Sci. Chapter 11: Human Body and Organ System

 

Chapter 11: Human Body 🧍and Organ🫁 System

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माहिती विज्ञानाची या ग्रुपला जॉईन होण्यासाठी खालील👇 लिंकला 🖇️ ला स्पर्श करा.

माहिती विज्ञानाची 🎷

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1. Life Processes & Organ Systems

Life Processes: Vital processes essential for living beings (e.g., digestion, respiration, circulation, and excretion).  

Organ System: A group of specific organs working together to perform a specific function.  

Energy Requirement: Cells produce energy using soluble nutrients and oxygen via respiration and circulation.  

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2. Human Respiratory System

Steps of Respiration 🫁 

External Respiration:

Inspiration / Inhalation: 

Air is drawn through the nose into the lungs via the trachea (wind pipe).  

Expiration/Exhalation: Oxygen enters the blood, while blood carries CO₂ from body tissue to the lungs to be exhaled.  

Internal Respiration: Exchange of gases (O₂ and CO₂) between blood cells and tissue fluid.  

Cellular Respiration: Oxidation of dissolved nutrients like glucose inside cells to release energy as ATP, alongside waste products CO₂ and water vapor.

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Organs of the Respiratory System

Nose: Filters air using hair and mucus.  

Pharynx: 

Common passage for the food pipe and windpipe. 

A lid (epiglottis) covers the wind pipe during swallowing to prevent food entry.  

Windpipe (Trachea): Contains the sound box (larynx) at its upper end and bifurcates into two bronchi entering each lung.  

Lungs:

Double-layered membrane cover called pleura.  

Elastic structure filled with small compartments called alveoli surrounded by capillaries.  

Gas Exchange: Hemoglobin in RBCs absorbs oxygen in alveoli while CO₂ and water vapor diffuse into alveoli for exhalation.  

Diaphragm: A muscular partition between the thoracic and abdominal cavities that creates pressure differences to drive breathing.  

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3. 🫀Human Circulatory System

In 1628, William Harvey described the mechanism of circulation in the body.

Heart Structure & Function

Location & Protection: 

Centered in the thoracic cage, behind ribs, inclined left. 

Covered by a double-layered peritoneal membrane filled with fluid for shock absorption.  

Structure: Muscular organ made of involuntary cardiac muscles. Divided into 4 chambers: upper atria (right & left) and lower ventricles (right & left).  

Weight: ~360 grams; size of an individual's closed fist.  

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• In case of a healthy person, there are 72 beats of heart per minute. 
• Two types of sounds are heard during a heartbeat. One is described as 'lubb' and the other as 'dub.' 
• The heart pumps about 75 ml of blood during each beat.

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Blood Vessel

👉 Arteries 

1. Function of Arteries: Arteries carry blood away from the heart.
2. Blood Type: Oxygenated (except Pulmonary Artery) 
3. Location: Deeply located.
4. Walls & Valves: Thick walls, no valves.

👉 Veins 

1. Function of Veins: Carry blood towards the heart.
2. Blood Type: Deoxygenated (except pulmonary vein) 
3. Location: Superficially located
4. Walls & Valves: Thin walls, contain valves.

👉 Capillaries

1. Function of capillaries: Connect arteries to veins for exchange.
2. Blood Type: Mixed exchange zone
3. Location: Present in all organs
4. Walls & Valves: Single-cell layer wall, no valves

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4. Blood Components & Functions

Blood Properties: Fluid connective tissue, red color, salty taste, pH 7.4.  

Components of Blood

Plasma (55%): Pale yellow, slightly alkaline fluid containing 90–92% water, 6–8% proteins, and 1–2% inorganic salts.  

Albumin: Water balance.  

Globulins: Protection/immunity.  

Fibrinogen & Prothrombin: Blood clotting.  

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Blood Cells:

👍 Red Blood Corpuscles (RBCs): 

Enucleated, circular, containing hemoglobin. Count: 50–60 lakh mm³; 

Lifespan: 100–127 days.  

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✌ White Blood Cells (WBCs): 

Nucleated, defender cells. Count: 5000–10000 mm³. 

Types: 

• Basophils, 
• eosinophils, 
• neutrophils, 
• monocytes, and 
• lymphocytes.  

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👌 Platelets: 

• Disc-shaped fragments involved in blood clotting. 
• Count: 2.5–4 lakh mm³.  

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🩸Functions of Blood

1. Transport of gases : Oxygen is carried via blood from lungs to cells in various parts of body and carbon dioxide from tissues to lungs. 

2. Transport of nutrients : Simple nutrients like glucose, amino acids, fatty acids are taken up by blood from wall of alimentary canal and transported up to each cell in the body. 

3. Transport of waste materials : Nitrogenous wastes like ammonia, urea, creatinine are released by tissues into blood which carries those to kidney for excretion. 

4. Protection : Antibodies are produced in the blood and they protect the body from microbes and other harmful particles. 

5. Transport of enzymes and hormones : Blood transports the enzymes and hormones from the site of their production to the site of their action. 

6. Thermoregulation : Body temperature is maintained constant at 37 0C by vasodilation and vasoconstriction. 

7. Maintaining the balance of minerals like Na, K in the body. 

8. If bleeding occurs at the injury, platelets and a protein called fibrinogen of the blood form a clot and seal the injury

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5. Blood Groups, Pressure & Important Terms

Blood Groups

System: 

🅰️, 🅱️, 🆎, and 🅾️  blood groups are categorized by antigens and antibodies. 

Further classified as Rh positive (+ve) or Rh negative (-ve).  

Universal Donor: Group 'O'  

Universal Recipient: Group 'AB'  

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Discoveries: 

A, B, and O blood groups were discovered by Carl Landsteiner (1900); 

AB was discovered by Decastello and Sturli (1902).  

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💪Blood Pressure (BP)

Measured using a sphygmomanometer.  

Normal Range: 120/80 mm Hg to 139/89 mm Hg.  

Systolic Pressure: Contraction phase (90–119 mm Hg normal).  

Diastolic Pressure: Relaxation phase (60–79 mm Hg normal).  

Hypertension: High blood pressure exceeding standard limits.  

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William Harvey (1628): Discovered the mechanism of blood circulation and heart valves.  

Hematology: The branch of medical science dealing with the study of blood, hematopoietic organs, and blood diseases.  

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