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

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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5. Blood Groups, Pressure & Important Terms

Blood Groups

System: 

A, B, AB, and O 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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