Grade 8 General Science: Scientific Measurement PDF

Created by Turbolearn AI Grade 8 General Science: Scientific Measurement Indigenous Methods of Measurement This section explores traditional Ethiopian measurement techniques. These methods were passed down through generations and are still relevant in some contexts. Length Length, the distance bet...

Created by Turbolearn AI Grade 8 General Science: Scientific Measurement Indigenous Methods of Measurement This section explores traditional Ethiopian measurement techniques. These methods were passed down through generations and are still relevant in some contexts. Length Length, the distance between two points, was measured using various body parts: Hand-span: Distance from the tip of the little finger to the thumb when the hand is stretched out. Digit: Width of an adult male fingertip. Cubit: Distance from the elbow tip to the middle fingertip with an extended arm. Foot: Distance from the heel to the big toe. Pace: Distance from the heel of one foot to the heel of the same foot after a normal walking step. Arm span (Fathom): Distance between the middle fingertips of both outstretched arms. These measurements are inherently variable depending on the individual making the measurement. This highlights the importance of standardized units. Mass Mass, the amount of matter, was measured using: Weqet: Unit for measuring gold powder. Quntal: A bag representing 100 kilograms of grains. Feresula: Unit for measuring pepper and coffee (17 kg). Page 1  Created by Turbolearn AI The reliability of these methods varies due to inconsistent bag sizes and the variability of the materials being measured. Time Time, the duration of an interval, was traditionally estimated using: Shadow of a tree: Observing changes in shadow length throughout the day to approximate the time. Longer shadows indicate morning or late afternoon; no shadow indicates noon. This method relies on consistent sunlight and a fixed object. It is imprecise, affected by cloud cover and the tree's position. Volume Volume, the space occupied by an object, was measured using various containers: Jog: Plastic cup for measuring liquids. Tassa: Can for measuring cereals, pulses, liquids, and solids. Sini: Small ceramic cup for coffee, pulses, and spices. Birchiko: Glass for pulses and liquids. Kubaya: Mug for cereals, pulses, and liquids. The varying sizes of these containers make consistent measurements difficult. Physical Quantities and Scientific Methods of Measurement This section defines physical quantities and introduces the International System of Units (SI). Fundamental Physical Quantities Physical quantities are measurable properties of objects. They are categorized into: Page 2  Created by Turbolearn AI Fundamental quantities: Cannot be expressed in terms of other quantities. The seven fundamental quantities are length, mass, time, temperature, electric current, luminous intensity, and amount of substance. This section focuses on length, mass, time, and temperature. Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Second s Temperature Kelvin K Derived quantities: Expressed in terms of fundamental quantities. Examples include area, volume, density, and force. The SI system provides a standardized approach to measurement, ensuring consistency and accuracy across various contexts. Measurements are expressed as a numerical value and a unit. For example, a mass of 32 kg indicates that the value is 32 and the unit is the kilogram (kg). Units and Measurement Study Guide Fundamental and Derived Units The first part of a measurement indicates the magnitude of the quantity, and the second indicates the unit (standard) of that quantity. Units are classified into two groups: Fundamental Units: Used to measure fundamental quantities. These don't depend on any other unit. Quantity Unit Name Symbol Length Meter m Mass Kilogram kg Time Second s Temperature Kelvin K Derived Units: Used to measure derived quantities. These depend on one or more fundamental quantities for their measurement. Examples include speed, area, volume, density, and force. Derived units are described by mathematically combining (dividing, multiplying, or powering) the base units. Page 3  Created by Turbolearn AI Derived Quantity Symbol Unit Area A m2 Volume V m3 Speed v m/s Density ρ kg/m 3 Example 1.1: Deriving units: (a) Area: Area = length × width. Since length and width are measured in meters (m), the unit of area is m × m = m 2. (b) Speed: Speed = distance/time. The unit of distance is meters (m), and the unit of time is seconds (s), so the unit of speed is m/s. Prefixes and Unit Conversion Science deals with very large and very small numbers. Prefixes provide a shorthand way of writing these numbers. Prefix Symbol Decimal Representation Mega M 1,000,000 Kilo k 1,000 Centi c 0.01 Milli m 0.001 Micro μ 0.000001 Converting between units usually involves moving a decimal point. Knowing the prefix values allows for easy conversion by multiplying or dividing. Example 1.2: Converting 6.5 kg to g: Since "kilo" (k) represents 1000, 6.5 kg = 6.5 × 1000 g = 6500 g Example 1.3: Converting 200 meters to kilometers: Since 1 km = 1000 m, 200 m = 200 m / 1000 m/km = 0.2 km Measuring Physical Quantities Page 4  Created by Turbolearn AI Measurement: The process of determining the size, amount, or degree of something. This section describes how to measure mass, length, and time. Measuring Mass Mass: A measure of the amount of matter in an object. Instruments used to measure mass are called balances. They compare the mass of an object to a known mass. The SI unit of mass is the kilogram (kg). Grams (g) and milligrams (mg) are also commonly used. 1 kg = 1000 g 1 g = 1000 mg Example 1.4: Converting 1200 g to kg: 1200 g = 1200 g / (1000 g/kg) = 1.2 kg Measuring Length Length: A measure of the distance between two points. The SI unit of length is the meter (m). Kilometers (km), centimeters (cm), and millimeters (mm) are also used. 1 km = 1000 m 1 m = 100 cm 1 cm = 10 mm Example 1.5: Converting 1 meter to millimeters: 1 m = 100 cm = 100 cm × 10 mm/cm = 1000 mm Measuring Time Time: A measure of duration. The SI unit of time is the second (s). Hours, minutes, days, and years are also used. Page 5  Created by Turbolearn AI 1 hour = 60 minutes 1 minute = 60 seconds 1 day = 24 hours Example 1.6: Converting 1 hour to seconds: 1 hour = 60 minutes × 60 seconds/minute = 3600 seconds Time Conversions Solution: 1 hour = 60 minutes = 60 * 60 seconds = 3600 seconds. Exercise 1.8: How many (a) minutes, and (b) seconds are there in one day? Measuring Temperature A thermometer is used to measure temperature. The SI unit of temperature is Kelvin. Other units include degrees Celsius (°C) and degrees Fahrenheit (°F). Thermometers can be analog or digital (see Figure 1.7). Activity 1.4: Measure the body temperature of two students and compare to the standard body temperature of 37°C. Discuss observations. When using a thermometer, hold it at the top; do not hold the bulb or let it touch the glass. Activity 1.5: Measure the temperature of warm water using a laboratory thermometer. Record observations. Safety Note: Never put a laboratory thermometer in your mouth. Accuracy and Precision in Measurement Page 6  Created by Turbolearn AI Accuracy: How close a measurement is to its known value. Example 1.7: A measured mass of 8.2 kg vs. a known mass of 10 kg is not accurate. Precision: How close multiple measurements are to each other, regardless of accuracy. Example 1.8: Measurements of 3.2 kg, 3.1 kg, 3.25 kg, 3.3 kg, and 3.2 kg are precise but not accurate compared to a known value of 10kg. Precision is independent of accuracy. Exercise 1.9: Analyze dart game results (Figure 1.8) to determine accuracy and precision (accurate and precise, accurate but not precise, precise but not accurate, neither precise nor accurate). Exercise 1.10: Define: physical quantity, fundamental quantity, derived quantity. State indigenous measurement methods used in Addis Ababa. What are prefixes? Explain the difference between accuracy and precision. Doing Scientific Investigation Page 7  Created by Turbolearn AI 1.2 Scientific Method: The process by which scientists approach their work. The steps may be modified depending on the specific question and scientific field. Activity 1.6: What are the applications of the scientific method? Steps of the Scientific Method: 1. Ask Questions: Begin with observations leading to measurable, answerable questions (how, what, when, why, where, who, which). 2. Perform Background Research: Gather information through online searches or libraries. 3. Establish your Hypothesis: Formulate a tentative explanation based on gathered data. The hypothesis should include testable predictions. 4. Test your Hypothesis: Conduct experiments to test predictions. Repeat the experiment to ensure accuracy. Maintain consistent conditions to ensure fairness. 5. Analyze the Results and Draw a Conclusion: Determine if the results support the hypothesis. If not, create a new hypothesis and repeat from step 3. 6. Communicating Results: Share findings with others through various methods (scientific papers, blogs, articles, conferences, etc.). Describe methods and potential problems. Example 1.9: A simple candle experiment demonstrating the need for air for burning, illustrating the scientific method steps. Activity 1.7: Conduct investigations on: Effect of sunlight on bean plant growth. Does a coiled nail act like a magnet? How do plants store food in their leaves? Exercise 1.13: Describe the components of a scientific investigation. Project 1.3: Conduct investigations using local materials and methods (e.g., making injera). (See Figures 1.11 and 1.12) Key Terms: Fundamental quantity, derived quantity, fundamental unit, derived unit, prefix, accuracy, precision, scientific method. Introduction to Fundamental and Derived Quantities Page 8  Created by Turbolearn AI The fundamental quantities are the basic quantities that cannot be expressed in terms of other quantities. Examples of fundamental quantities include length, mass, time, and temperature. On the other hand, derived quantities are quantities that can be expressed in terms of fundamental quantities. Examples of derived quantities include area, volume, density, and force. Definitions Accuracy refers to how close a measurement is to the accepted value. Precision refers to how close measurements are to each other. Fundamental vs Derived Units The main difference between fundamental units and derived units is that fundamental units are the basic units of measurement, while derived units are units that can be expressed in terms of fundamental units. For example, the meter is a fundamental unit of length, while the kilometer is a derived unit of length. Examples of Fundamental and Derived Quantities Quantity Unit Length meter (m) Mass kilogram (kg) Time second (s) Temperature kelvin (K) Area square meter (m²) Volume cubic meter (m³) Density kilogram per cubic meter (kg/m³) Force newton (N) Prefixes Prefixes are used to represent very large or very small numbers. For example: Page 9  Created by Turbolearn AI kilo- represents 1000 mega- represents 1,000,000 centi- represents 0.01 milli- represents 0.001 Scientific Method The scientific method is the process by which scientists approach their work. It involves: Observing a phenomenon Asking a question Hypothesizing an answer Testing the hypothesis Drawing conclusions Atomic Structure The atom is the building block of matter. It consists of a tiny dense nucleus surrounded by electrons. The nucleus contains positively charged protons and neutral neutrons. Subatomic Particles Particle Charge Mass Proton positive approximately 1800 times the mass of an electron Neutron neutral approximately 1800 times the mass of an electron Electron negative approximately 1/1800 the mass of a proton or neutron Atomic Number and Mass Number The atomic number is the number of protons in an atom's nucleus, while the mass number is the total number of protons and neutrons in an atom's nucleus. Molecules A molecule is a group of atoms that are chemically bonded together. Molecules can be composed of atoms of the same element (molecules of elements) or atoms of different elements (molecules of compounds).# Atomic Structure and Molecules Page 10  Created by Turbolearn AI Atoms Atoms are made up of smaller particles called subatomic particles: Protons: Positively charged (+1). Mass ≈ 1.673 x 10⁻²⁴ g. Electrons: Negatively charged (-1). Mass ≈ 9.109 x 10⁻²⁸ g (approximately zero). Neutrons: No charge (0). Mass ≈ 1.675 x 10⁻²⁴ g. Protons and neutrons reside in the nucleus, while electrons occupy the space surrounding the nucleus. Most of an atom's volume is occupied by electrons. Actual Mass Relative Mass Actual Charge Relative Particle Location (g) (amu) (C) Charge +1.60218 x Proton Nucleus 1.673 x 10⁻²⁴ 1.00728 +1 10⁻¹⁹ Outside -1.60218 x Electron 9.109 x 10⁻²⁸ 0.00055 -1 nucleus 10⁻¹⁹ Neutron Nucleus 1.675 x 10⁻²⁴ 1.00866 0 0 Atomic Number and Mass Number Atomic Number (Z): The number of protons in an atom's nucleus. This also equals the number of electrons in a neutral atom. Mass Number (A): The sum of protons and neutrons in an atom's nucleus. A = Number of protons + Number of neutrons = Z + Number of neutrons For example, the notation 12 6 C indicates Carbon (C) with a mass number of 12 and an atomic number of 6. Determining Subatomic Particles To determine the number of protons, electrons, and neutrons: Protons: Number of protons = Atomic number (Z) Electrons: Number of electrons = Atomic number (Z) (in a neutral atom) Neutrons: Number of neutrons = Mass number (A) - Atomic number (Z) Page 11  Created by Turbolearn AI Molecules A molecule is the smallest unit of a substance that can exist independently and retain the properties of that substance. Molecules of Elements Molecules of elements contain only one type of atom: Monoatomic: One atom (e.g., He, Ne, Ar). Diatomic: Two atoms (e.g., O₂, H₂, N₂). Polyatomic: More than two atoms (e.g., O₃, P₄, S₈). Molecules of Compounds Molecules of compounds contain two or more different types of atoms combined chemically (e.g., H₂O, NH₃, CO₂). Grade 8 General Science: Classification of Compounds Review Exercise I: True or False Nucleus consists of protons and neutrons. True Atomic number is the number of protons in the nucleus. True Molecules of elements consist of two or more different types of atoms. False Proton and electron have approximately the same mass. False Different elements have the same number of protons. False Review Exercise II: Multiple Choice 択一式 Page 12  Created by Turbolearn AI 6. The idea that matter is continuous was proposed by: B. Aristotle 7. The idea of atoms was first proposed by the Greek philosopher: D. Democritus 8. Which of the following particles are located in the nucleus of an atom? B. Neutron and proton 9. The sum of the number of protons and neutrons in an atom is known as: C. Mass number 10. The number of neutrons in 126 Mg are: B. 11 11. Which of the following statements concerning the nucleus of an atom is correct? C. Is always positively charged 12. Which of the following molecules is a diatomic molecule? A. O₂ 13. Which of the following statements is false? C. Molecules of compounds consist of only one type of atom. 14. Which of the following molecules is a molecule of an element? C. H₂ Review Exercise III: Short Answers 15. What are the two main parts of an atom? The two main parts of an atom are the nucleus and the electron cloud. 16. What are the fundamental subatomic particles? The fundamental subatomic particles are protons, neutrons, and electrons. 17. Determine the atomic number, number of protons, number of neutrons, number of electrons, and mass number for 16 8 O. Property Value Atomic Number 8 Number of Protons 8 Number of Neutrons 8 Number of Electrons 8 Mass Number 16 Page 13  Created by Turbolearn AI 3.1 Introduction: Organic vs. Inorganic Compounds Organic compounds were initially defined as compounds obtained from living organisms. Inorganic compounds were those obtained from minerals. The "vital force" theory, which stated that organic compounds required a special force from living organisms to be created, was disproven by Friedrich Wöhler in 1828, when he synthesized urea (an organic compound) from ammonium cyanate (an inorganic compound). Modern definitions: Organic compounds contain carbon and hydrogen, along with other elements such as oxygen, nitrogen, sulfur, halogens, and phosphorus (exceptions include carbon oxides, carbonates, hydrogen carbonates, cyanides, and cyanates). Inorganic compounds are generally those that do not contain carbon. 3.2 Organic Compounds: Hydrocarbons углеводороды A hydrocarbon is a compound containing only carbon and hydrogen atoms. Alkanes General formula: C n H 2n+2 Examples: CH₄ (methane), C₂H₆ (ethane), C₃H₈ (propane), C₄H₁₀ (butane) A homologous series is a family of compounds where each member differs from the next by a methylene (-CH₂-) group. Alkanes are a homologous series. Alkenes General formula: C n H 2n Examples: C₂H₄ (ethene), C₃H₆ (propene), C₄H₈ (butene) Alkynes Page 14  Created by Turbolearn AI General formula: C n H 2n−2 Examples: C₂H₂ (ethyne), C₃H₄ (propyne), C₄H₆ (butyne) Alkanes, Alkenes, and Alkynes Alkane Formula The general formula for alkanes is C n H 2n+2 , where n = 2, 3, 4, etc. Examples: CH 4 (methane) C 3 H 8 (propane) C 4 H 10 (butane) Alkene Formula The general formula for alkenes is C n H 2n , where n = 2, 3, 4, etc. Examples: C 2 H 4 (ethene) C 4 H 8 (butene) Alkyne Formula The general formula for alkynes is C n H 2n−2 , where n = 2, 3, 4, etc. Examples: C 2 H 2 (ethyne) C 3 H 4 (propyne) C 4 H 6 (butyne) Hydrocarbon Nomenclature The naming of hydrocarbons is based on specific rules, not random assignment. The name is derived from: 1. A prefix indicating the number of carbon atoms (see Table 3.1 below). 2. A suffix indicating the type of hydrocarbon: -ane for alkanes -ene for alkenes -yne for alkynes Page 15  Created by Turbolearn AI The prefix specifies the number of carbon atoms, while the suffix (-ane, - ene, -yne) designates the type of hydrocarbon. Number of Carbon Atoms Prefix 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Non- 10 Dec- Examples of Naming Hydrocarbons Example 1: Naming Alkanes CH 4 : One carbon atom; prefix "meth-"; suffix "-ane". Therefore, the name is methane. C 3 H 8 : Three carbon atoms; prefix "prop-"; suffix "-ane". Therefore, the name is propane. Example 2: Naming Alkenes C 2 H 4 : Two carbon atoms; prefix "eth-"; suffix "-ene". Therefore, the name is ethene. C 4 H 8 : Four carbon atoms; prefix "but-"; suffix "-ene". Therefore, the name is butene. Example 3: Naming Alkynes C 3 H 4 : Three carbon atoms; prefix "prop-"; suffix "-yne". Therefore, the name is propyne. C 4 H 6 : Four carbon atoms; prefix "but-"; suffix "-yne". Therefore, the name is butyne. Uses of Common Organic Compounds Page 16  Created by Turbolearn AI Methane (CH 4 ): Used as fuel for cooking, heating, and generating electricity; main constituent of biogas. Propane (C 3 H 8 ) and Butane (C 4 H 10 ): Mixture compressed and stored in cylinders (bottled gas/butagas) for cooking and heating. Ethyne (C 2 H 2 ): Used to produce oxyacetylene flame for cutting and welding steel and iron. Ethanol (Ethyl alcohol): Used in alcoholic beverages; mixed with petrol as fuel; used in production of acetic acid; used as a disinfectant. Ethanoic Acid (Acetic acid): Found in vinegar; used as a food flavoring agent and disinfectant. Formalin: Aqueous solution of formaldehyde (40% by volume); used for preserving biological specimens. Grade 8 General Science: Inorganic Compounds Oxides Oxides: Binary compounds containing oxygen and any other element. Element + Oxygen → Oxide. Examples include water (H₂O), carbon dioxide (CO₂), lime (CaO), and rust (iron (III) oxide). Not all compounds containing oxygen are oxides; the compound must be binary (only two elements). Types of Oxides Metallic Oxides: Metal + Oxygen → Metallic Oxide. Examples: CaO, Na₂O, Al₂O₃, MgO. Non-Metallic Oxides: Non-metal + Oxygen → Non-metallic Oxide. Examples: NO₂, H₂O, CO₂, SO₂, SO₃. Classification of Oxides by Properties Page 17  Created by Turbolearn AI Acidic Oxides: React with water to form acids or acidic solutions. Mostly non- metallic oxides. Examples: SO₂, P₄O₆, CO₂. React with bases to form salts and water: Acidic oxide + Base → Salt + Water. Examples: SO₃ + Ca(OH)₂ → CaSO₄ + H₂O; CO₂ + 2NaOH → Na₂CO₃ + H₂O React with basic oxides to form salts: Acidic oxide + Basic oxide → Salt. Examples: CO₂ + Na₂O → Na₂CO₃; SO₃ + CaO → CaSO₄ Basic Oxides: React with water to form bases or basic solutions. Mostly metallic oxides. Examples: Na₂O, Li₂O, CaO, MgO. React with acidic oxides to form salts: Basic oxide + Acidic oxide → Salt. Examples: CaO + CO₂ → CaCO₃; Na₂O + SO₃ → Na₂SO₄ React with acids to form a salt and water: Basic oxide + Acid → Salt + Water. Examples: CaO + 2HCl → CaCl₂ + H₂O; Na₂O + H₂SO₄ → Na₂SO₄ + H ₂O Laboratory Preparation of Oxides Preparation of Sulphur Dioxide (SO₂) Objective: Prepare SO₂ and test if it's an acidic or basic oxide. Procedure: Heat powdered sulfur in a deflagrating spoon until it burns, then place it in a gas jar. Add water, shake, and test with blue and red litmus paper. Observations: Observation Description Flame Color (To be determined experimentally) Blue Litmus Paper (To be determined experimentally) Red Litmus Paper (To be determined experimentally) Chemical Equation S + O₂ → SO₂ Oxide Classification (To be determined experimentally - acidic or basic) Preparation of Magnesium Oxide (MgO) Objective: Prepare MgO and test if it's an acidic or basic oxide. Page 18  Created by Turbolearn AI Procedure: Clean magnesium ribbon with sandpaper, burn it in a crucible, add water, and test with red and blue litmus paper. Observations: Observation Description Reason for Sandpaper Cleaning (To be determined experimentally) Flame Color (To be determined experimentally) Chemical Equation 2Mg + O₂ → 2MgO Red Litmus Paper Result (To be determined experimentally) Blue Litmus Paper Result (To be determined experimentally) Resulting Solution (Acidic/Basic) (To be determined experimentally) Acids and Bases Acids: Substances that release hydrogen ions (H⁺) in aqueous solution. They have a sour taste. Examples: lemon juice, vinegar, HCl, H₂SO₄, HNO₃. Bases: Oxides or hydroxides of metals that neutralize acids to form salt and water. Bases soluble in water are called alkalis. Alkalis release hydroxide ions (OH⁻) in aqueous solution. They have a bitter taste. Examples: NaOH, Ca(OH)₂. Naming Acids The general formula for an acid is H n X, where X is a monoatomic or polyatomic anion, and n is the number of hydrogen ions. The naming conventions are as follows: If the anion (X) ends in -ide, the acid name begins with the prefix hydro- followed by the stem of the anion with the suffix -ic and the word acid. If the anion name ends in -ite, the acid name is the stem of the anion with the suffix -ous, followed by the word acid. If the anion name ends in -ate, the acid name is the stem of the anion with the suffix -ic, followed by the word acid. Page 19  Created by Turbolearn AI Anion Ending Suffix Example Anion Acid Name Example Formula -ide hydro-ic Chloride (Cl⁻) Hydrochloric acid HCl -ite -ous Sulfite (SO₃²⁻) Sulfurous acid H₂SO₃ -ate -ic Nitrate (NO₃⁻) Nitric acid HNO₃ -ate -ic Sulfate (SO₄²⁻) Sulphuric acid H₂SO₄ Naming Bases Bases are named similarly to other ionic compounds: the name of the cation is followed by the name of the anion, which is hydroxide. Examples: NaOH (sodium hydroxide), Ca(OH)₂ (calcium hydroxide), NH₄OH (ammonium hydroxide) Acid-Base Indicators Acid-base indicators are dyes extracted from plants that change color in the presence of an acid or a base. Common examples include litmus, methyl orange, and phenolphthalein. Properties of Acids and Bases Properties of Acids Acids generally have a sour taste. Acids change the color of indicators. Reactions of Acids with Metals Dilute acids react with active metals (like zinc, magnesium, iron, and aluminum) to form salts and liberate hydrogen gas. Active Metal + Dilute Acid ⟶ Salt + Hydrogen Example: Ca + 2HCl ⟶ CaCl 2 + H 2 Mg + H 2 SO 4 ⟶ MgSO 4 + H 2 Page 20  Created by Turbolearn AI Reactions of Acids with Carbonates and Hydrogen Carbonates Acids react with carbonates and hydrogen carbonates to form salts, water, and carbon dioxide gas. Acid + Carbonate ⟶ Salt + W ater + Carbon Dioxide Example: 2HCl(aq) + CaCO 3 (s) ⟶ CaCl 2 (aq) + H 2 O(l) + CO 2 (g) Acid + Hydrogen carbonate ⟶ Salt + W ater + Carbon Dioxide Example: H 2 SO 4 (aq) + Ca(HCO 3 ) 2 (aq) ⟶ CaSO 4 (aq) + 2H 2 O(l) + 2CO 2 (g) Grade 8 General Science: Acids and Bases Experiment 3.5: Acid Reactions with Carbonates Objective: To investigate the reaction between acids and carbonates. Materials: Dilute hydrochloric acid, dilute sulfuric acid, calcium carbonate, sodium hydrogen carbonate, test tubes, test tube rack, limewater (calcium hydroxide solution), spatula, rubber stopper. Procedure: Page 21  Created by Turbolearn AI 1. Add calcium carbonate to a test tube and limewater to another. 2. Add dilute hydrochloric acid to the calcium carbonate, stopper immediately, and hold it inclined. 3. Bring the limewater test tube close to the calcium carbonate test tube. 4. Remove the stopper, allowing gas to escape into the limewater. Observe for color change. 5. Repeat steps 2-4 using sodium hydrogen carbonate and dilute sulfuric acid. Observations and Analysis: Is there bubble formation in step 2? If so, what does this indicate? What happens to the limewater? Why? Write the balanced chemical equation for: Hydrochloric acid and calcium carbonate reaction. Sodium hydrogen carbonate and sulfuric acid reaction. The reaction in step 4. Experiment 3.6: Neutralization of Acid with Base Objective: Investigate the neutralizing effect of sulfuric acid on sodium hydroxide. Materials: Dilute hydrochloric acid, sodium hydroxide solution, conical flask, phenolphthalein, burette, stand, clamp, measuring cylinder, blue and red litmus papers. Procedure: 1. Set up the apparatus as shown in Figure 3.6 (diagram not provided in text). 2. Fill the burette with dilute hydrochloric acid. 3. Add 20 mL sodium hydroxide solution and 5 drops phenolphthalein to a conical flask. 4. Add hydrochloric acid from the burette to the flask, shaking continuously. 5. Add acid dropwise when the color starts to disappear. 6. When color disappears completely, stop and test with litmus paper. Observations and Analysis: Page 22  Created by Turbolearn AI What color appeared when phenolphthalein was added? Why did the color disappear in step 6? Did the solution affect the litmus paper? Write the balanced chemical equation for the reaction. Properties of Bases Bases have a bitter taste. Bases change the color of indicators. Experiment 3.7: Effect of Bases on Indicators Objective: To study the effect of bases on indicators. Materials: Red and blue litmus papers, phenolphthalein solution, methyl orange, diluted sodium hydroxide (NaOH) solution, test tubes, test tube holder, and test tube rack. Procedure: 1. Take four clean test tubes. 2. Add 5 mL NaOH solution to each test tube. 3. Add red litmus paper, blue litmus paper, phenolphthalein, and methyl orange to separate test tubes. 4. Observe and record color changes. 5. Repeat using ammonia solution. Observations and Analysis: Base Red Litmus Blue Litmus Phenolphthalein Methyl Orange Dilute NaOH NH₄OH solution What do you conclude from this experiment? Bases Neutralize Acids Bases react with acids (and acidic oxides) to form salt and water. Base + Acid → Salt + W ater Page 23  Created by Turbolearn AI Example : Ca(OH) 2 + H 2 SO 4 → CaSO 4 + 2H 2 O Experiment 3.8: Neutralization of Acid by Base Objective: Investigate the neutralizing effect of sodium hydroxide on hydrochloric acid. Materials: Sodium hydroxide solution, hydrochloric acid, conical flask, phenolphthalein, burette, stand, clamp, measuring cylinder, blue and red litmus papers. Procedure: (Similar to Experiment 3.6, but using sodium hydroxide in the burette). Observations and Analysis: (Similar to Experiment 3.6) Project Work: Natural Indicator from Beetroot Objective: Prepare a natural indicator using beetroot. Materials: Beetroot, knife, water, spoon, boiler, lemon juice (citric acid). Procedure: 1. Wash, peel, and chop beetroot. 2. Boil the beetroot pieces for 30-60 minutes. 3. Filter and collect the juice. 4. Add beetroot juice to lemon juice. Observations and Analysis: What color appeared in step 5? Why did the color change? Is the indicator effective? What do you conclude? Discuss the characteristics of a good indicator. Safety Precautions with Acids and Bases Acids: Can cause severe burns, eye injury, or internal damage. If spilled on skin, wash thoroughly with water and then with 10% Na₂CO₃ solution. If in eyes, flush with water and seek medical attention. If ingested, take a base like Mg(OH)₂. Bases: Similar dangers as acids. Handle with care. Page 24  Created by Turbolearn AI Lecture Notes: Acids, Bases, and Neutralization Reactions Handling Acids and Bases Safely Acid spills on skin: Wash with plenty of water, then treat with a weak acid like dilute acetic acid to neutralize. Base spills on skin: Wash with plenty of water, then treat with a weak acid like dilute acetic acid to neutralize. Acid/base in eyes: Flush with plenty of cold water and seek medical attention immediately. Accidental ingestion of acid/base: Neutralize with a dilute solution of acetic acid or lemon juice (for bases) and seek medical attention immediately. Spills on work surfaces: Wipe up immediately. Spills on clothing: Wash the affected area with running tap water. Neutralization Reaction and Salts Neutralization reaction: The reaction of acids with basic oxides or bases to form salt and water. Everyday Uses of Neutralization Toothpaste: Neutralizes acids produced by bacteria in the mouth. Baking powder: Used in baking (although the reaction is more complex than simple neutralization). Hair conditioner: Neutralizes the effects of shampoo, preventing hair from becoming dry and unmanageable. Antacids: Neutralize excess stomach acid. Contains bases such as aluminum hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂). Vinegar: (Acidic) used to treat alkaline wasp stings. Baking soda: (Alkaline) used to treat acidic bee stings and ant bites. Agriculture: Acidic soil is treated with lime (CaO), limestone (CaCO₃), or wood ash. Acidic gases from decomposing compost neutralize alkalis in basic soil. Salts: Definition and Examples Page 25  Created by Turbolearn AI Salt: A compound consisting of the positive ion of a base and the negative ion of an acid. The positive ion can be a metal ion or ammonium ion. Examples of salts: Sodium chloride (NaCl), calcium carbonate (CaCO₃), potassium nitrate (KNO₃), sodium bicarbonate (NaHCO₃), diammonium phosphate ((NH₄)₂HPO₄). Naming and Writing Formulas of Salts Rules for naming salts: 1. The first part of the name comes from the base. 2. The second part comes from the acid (drop "hydro" and change "-ic acid" to "- ide"). Example: Sodium hydroxide (base) + Hydrochloric acid (acid) → Sodium chloride (salt) + Water Rules for writing salt formulas: 1. Break the salt name into cation (positive ion from the base) and anion (negative ion from the acid). 2. Determine the formulas for the cation and anion. 3. Criss-cross the charges (subscripts) to balance the overall charge and simplify if possible. Example: Calcium carbonate 1. Cation: Calcium (Ca²⁺) 2. Anion: Carbonate (CO₃²⁻) 3. Formula: CaCO₃ Common Salts: Names and Formulas Name of Acid Group Name of Salt Example of Salt Formula Carbonic acid (H₂CO₃) Carbonates Calcium carbonate CaCO₃ Hydrochloric acid (HCl) Chlorides Sodium chloride NaCl Sulphuric acid (H₂SO₄) Sulphates Calcium sulphate CaSO₄ Nitric acid (HNO₃) Nitrates Sodium nitrate NaNO₃ Page 26  Created by Turbolearn AI Activity 3.13: Exploring Salts and Chemical Compounds This activity involves group work using chemistry reference books. You will prepare a table and a short presentation. Table of Salts and Their Uses Name of the Salt Formula of the Salt Uses Sodium chloride Sodium bicarbonate Potassium nitrate Presentation: Uses of Salts (5 minutes) Prepare a five-minute presentation on the uses of the salts listed above. Organic vs. Inorganic Compounds Chemical compounds are broadly classified into two groups: organic and inorganic compounds. Organic compounds primarily contain carbon and hydrogen atoms, along with other elements like nitrogen, oxygen, and sulfur. Exceptions include oxides of carbon, carbonates, and hydrogen carbonates. Hydrocarbons are organic compounds containing only carbon and hydrogen. Types of Hydrocarbons Alkanes (paraffins): General formula: C n H 2n+2 (n = 1, 2, 3...) Alkenes (olefins): General formula: C n H 2n (n = 2, 3, 4...) Alkynes: General formula: C n H 2n−2 (n = 2, 3, 4...) Page 27  Created by Turbolearn AI Inorganic compounds are compounds that do not contain carbon, except for oxides of carbon, carbonates, and hydrogen carbonates. They are classified as oxides, acids, bases, and salts. Inorganic Compound Classification Oxides: Binary compounds containing oxygen and another element (metal, non-metal, or metalloid). Classified as acidic (non-metallic oxides forming acidic solutions in water) or basic (metallic oxides forming basic solutions in water). Acids: Release hydrogen ions (H + ) in water. Bases: Neutralize acids to form salt and water. Alkalis are bases that release hydroxide (OH − ) ions in aqueous solution. Salts: Contain positive ions from bases and negative ions from acids. Important Note: Acids and bases are dangerous and corrosive. Handle with care; avoid skin contact. Indicators change color depending on whether a solution is acidic or basic. Neutralization is the reaction of acids with bases to form salt and water. It is important in daily life (home, health, agriculture). Review Exercise This section contains multiple-choice and short-answer questions to test your understanding. (Questions 1-22 have been omitted for brevity as they are extensive. This section would contain those questions here in a study guide.) The Integumentary System ‍ Layers of the Skin Layered Page 28  Created by Turbolearn AI Epidermis: Outer layer, made of dead cells. Reduces water loss, protects from UV light and microorganisms. Dermis: Middle layer. Contains blood vessels (thermoregulation), lymph vessels, sweat glands, sensory receptors, and hair follicles. Hypodermis: Lower layer (also called subcutaneous layer). Contains fatty tissue for energy storage and insulation. Hair Follicles Hair grows from follicles, simple organs made of epithelial cells. The hair shaft is composed of: Medulla: Deepest layer, only in large, thick hairs. Cortex: Middle layer, provides strength, color, and texture. Cuticle: Outer layer, thin and colorless, protects the cortex. Hair functions include skin protection, body temperature regulation, and assisting in evaporation and perspiration. Nails Nails are hard coverings at finger and toe ends. Components include: Nail plate: Visible part. Nail bed: Skin under the nail plate. Cuticle: Tissue at the nail base. Nail folds: Skin folds on the sides of the nail plate. Lunula: White, half-moon-shaped area. Matrix: Invisible part under the cuticle; responsible for nail growth. Glands Glands produce substances like hormones, digestive juices, sweat, tears, saliva, or milk. The integumentary system has four types of exocrine glands (secrete substances outside the cell and body): Page 29  Created by Turbolearn AI Sudoriferous glands: Sweat glands; excrete sweat through skin openings. Sebaceous glands: Release oil into hair follicles for lubrication and protection. Ceruminous glands: In the ear canal; produce ear wax (cerumen) for protection. Mammary glands: In females; produce breast milk after childbirth. Exocrine gland: A gland that releases its secretion through ducts or openings. Functions of the Integumentary System The skin has several vital functions: Barrier and environmental protection. Temperature regulation. Pigment and vitamin D production. Sensory perception. Homeostasis. The skin contains many sensory organs for touch, temperature, pressure, and pain. Hair primarily insulates the body by creating a physical barrier against cold air and trapping warm air. Nails protect the fingertips and toes and provide tactile sensation. Glands secrete various chemicals for waste excretion, body cooling, hair lubrication, ear wax production, and breast milk production. Major Skin Diseases and Disorders Many conditions affect the skin, including those caused by bacterial, viral, or fungal infections, allergic reactions, skin cancers, and parasites. Severity and symptoms vary widely. Examples include: Page 30  Created by Turbolearn AI Acne: Blocked pores with oil, dead skin, or bacteria. Often found on the face, neck, shoulders, chest, and upper back. Rosacea: Skin condition often associated with redness. Multiple subtypes with varying symptoms. Eczema: Persistent skin condition; dryness, rashes, redness, swelling, itching, crusting, cracking, or bleeding. Hives: Itchy, raised welts, often from allergic reactions or other factors like stress, illness, or tight clothing. Warts: Caused by viral infections (HPV); often appear on hands or feet. Cold sores: Fluid-filled blisters near the mouth caused by the herpes simplex virus. Carbuncle: Infection in hair follicles caused by Staphylococcus aureus bacteria; red, irritated lump filled with pus. Blister: Fluid-filled bubble under the skin; serum provides natural protection if unopened. Actinic keratosis: Rough, scaly patch from years of sun exposure. Latex allergy: Reaction to proteins in natural rubber latex; can cause itchy skin, hives, or anaphylaxis. Chickenpox: Itchy, red rash with fluid-filled spots that crust over; caused by the varicella-zoster virus. 4.1 Integumentary System Skin Diseases Page 31  Created by Turbolearn AI 1. Multiple Choice Questions: The outer layer of the body is called ______ A. lung B. hair C. skin D. gland Which one of the following is not used to prevent skin diseases? A. washing B. keep skin moist C. avoid smoking D. good sanitation E. none ___ is a skin disease and characterized by a bubble of fluid under the skin A. hives B. rosacea C. cold sore D. blister 4.2 Muscular System What are muscular systems? Muscles are tissues composed of cells called muscle fibers. Muscles perform various body movements such as pumping blood, maintaining stability and posture, digestion, circulation, and breathing. The muscular system is a collection of these systems. 4.2.1 Components of the Muscular System There are three distinct components: Page 32  Created by Turbolearn AI Skeletal muscles: These are the only muscles voluntarily controlled. Their contraction causes bone movement (e.g., chewing, talking, facial expressions). They are attached to bones. Smooth muscles: These line the inside of vital organs, blood vessels, eyes, airways, and organs such as the stomach, digestive, reproductive, and urinary tracts. Smooth muscle acts involuntarily. Cardiac muscle: Located only in the heart, cardiac muscle pumps blood involuntarily. It is autorhythmic (capable of spontaneous contraction without hormonal control). Did you know? Muscles account for around 40 percent of a person's weight, with the gluteus maximus being the largest muscle. 4.2.2 Functions of the Muscular System The muscular system consists of various muscle types, each playing a crucial role. Muscles enable movement, speech, and chewing, and control heartbeat, breathing, and digestion. All muscle cells share properties used commonly by each muscle type. Some properties include: Contractility: The ability of muscle cells to forcefully shorten. Muscles can only pull, never push. Extensibility: The ability of a muscle to be stretched. Extensibility is high in adults but reduces with age (spasticity). Excitability: The ability of muscle to respond to stimuli from motor neurons and hormones. Elasticity: The ability of a strained body to recover its size and shape after deformation. 4.2.3 Major Muscle Diseases and Disorders Muscle disorders affect the muscular system, mainly manifesting as skeletal muscle weakness. Causes vary, resulting in weak muscles and reduced strength. Some disorders include: Page 33  Created by Turbolearn AI Muscular dystrophy: Inherited diseases characterized by muscle weakness and wasting, with or without nerve tissue breakdown. Different types lead to strength loss, disability, and possible deformity. Muscle strains: Injuries to a muscle or tendon (tissue connecting muscles to bones). Also called pulled muscles, strains commonly occur in the lower back and hamstrings. 4.3 Skeletal System 4.3.1 Structural Components of the Skeletal System The skeletal system consists of bones and connective tissues (cartilage, tendons, ligaments). It is also called the musculoskeletal system. Bone: Mineralized connective tissue containing collagen and minerals (calcium phosphate). Calcium phosphate provides firmness and allows bones to be compact or spongy, providing support and organ protection. Bones are living organs, with an adult human skeleton containing 206 bones. Types of Bones Bones are categorized into four groups based on shape: Bone Description Examples Type Hard, compact, tubular, filled with yellow bone Upper/lower limbs, arm, Long marrow leg, finger, thigh Compact bones with chambers/partitions, no Short Wrist, finger, toe, ankle marrow Ribs, sternum, cranial Flat Thin, flat, compact, typically curved, no cavity bone, scapula Typically thin membranes with nerves and blood Hip bones, facial bones, Irregular vessels; small holes on the surface vertebrae Bones are also divided into two major groups based on position: Page 34  Created by Turbolearn AI Axial skeleton: Divides the body into equal right and left regions. Includes the skull, hyoid, vertebral column, and thoracic cage. Appendicular skeleton: Supports the limbs and connects them to the axial skeleton. Composed of bones of the upper and lower limbs, pectoral girdles, and pelvic girdle. Its main functions are body movement and protection of digestive, excretory, and reproductive organ systems. The Human Skeletal System The Skeletal System: Bones and Cartilage The pelvic girdle, also known as the hip girdle, is composed of two hip bones. The hind limbs (back limbs or appendages) consist of: Femur (upper leg or thigh) Tibia and Fibula (lower legs or shin) Patella (kneecap) Tarsals (ankles) Metatarsals (feet) Phalanges (toes) Cartilage: Provides flexible and elastic support for structures like the nose, trachea, and ears in adult humans. Tendon: A fibrous band of connective tissue connecting muscle to bone. Ligament: A stretchy, flexible band of tissue holding bones together at joints. Joints: Structure and Function Joint: A site where two or more bones or skeletal components are joined. Their main functions are keeping bones apart and holding them in place during movement or rotation. There are two main types of joints: Page 35  Created by Turbolearn AI 1. Immovable joints: Fixed in place and do not move (e.g., the skull). 2. Movable joints: Permit movement. These are categorized into types such as: Hinge joints: Allow movement in a single direction (e.g., elbow, knee, fingers, toes). Ball and socket joints: Allow movement in all directions (e.g., shoulder and hip joints). Functions of the Skeletal System Movement: Supports body weight, enabling standing and movement. Joints, connective tissue, and muscles work together for mobility. Blood cell production: Bone marrow within bones is the site of blood cell (WBC and RBC) formation in normal adults. Protection and support: Protects and supports the body, providing form and structure. Storage: Stores minerals (like calcium and mineral salts), fats in bone marrow, and calcium phosphate needed for blood clotting, nerve function, and muscle activity. Major Diseases of the Skeletal System Leukemia: Cancer of blood-forming tissues (bone marrow and lymphatic system). Osteopenia, osteitis deformans, and osteomalacia: Similar to osteoporosis; types of bone loss. Osteoporosis: Bones become thin and weak due to decreased density and quality. Osteoarthritis: Degradation of joints causing pain, tenderness, stiffness, locking, and sometimes effusion. Fracture: A break in the continuity of a bone (can be partial or complete). Review Questions Part I: Multiple Choice 1. How many bones are in an adult human? A) 126 B) 80 C) 206 D) 106 2. Which is NOT an example of the axial skeleton? A) skull B) hyoid C) thoracic D) none 3. A joint fixed in place and unable to move is a(n): A) movable joint B) immovable joint C) ligament D) all Page 36  Created by Turbolearn AI Part II: Matching Column A Column B Irregular bone A) filled with yellow bone marrow Flat bone B) finger, toes, wrist Long bone C) have blood vessels and nerves Short bone D) cranium, scapula, ribs Part III: Fill in the Blanks 1. Shoulder bone composed of _______ and _______. 2. ______ run through your body from front to back, dividing it into equal right and left regions. Part VI: Short Answer 1. During which stage of development do we tend to have fewer bones? Why? Human Digestive and Respiratory Systems The Digestive System Teeth The adult human dental formula is: I= 2/2, C= 1/1, P= 2/2, M= 3/3, where I = incisors, C = canines, P = premolars, and M = molars. To calculate the total number of teeth: add the upper and lower jaw teeth counts, then multiply by two. Stomach The stomach is a muscular bag producing enzymes like pepsin for protein digestion and hydrochloric acid. Small Intestine Page 37  Created by Turbolearn AI The duodenum, the first section of the small intestine, mixes food with bile (produced by the liver, stored in the gallbladder) and pancreatic enzymes. Bile: Neutralizes stomach acid, making the food alkaline. Emulsifies fats, breaking them into smaller droplets. The small intestine has villi for absorbing digested food into the bloodstream. Digestion end products (amino acids from protein, fatty acids and glycerol from fats) are absorbed into the blood. Large Intestine Located between the small intestine and the anus, its main function is water absorption and feces formation. Undigested food is removed through the anus (defecation: removal of waste from the body). Digestive System Diseases Constipation: caused by prolonged fecal retention in the large intestine leading to excessive water absorption. Prevention involves eating high-fiber foods and drinking plenty of water. Roughage: fibrous, indigestible material aiding food and waste passage through the gut. Diarrhea: watery feces, often caused by gut infections, resulting in strong gut contractions and dehydration. Prevention includes rehydration and medical treatment. Hemorrhoids (Piles): swollen veins in the lower rectum or anus. Internal hemorrhoids may bleed; external ones may cause pain. Prevention involves eating high-fiber foods, drinking fluids, and exercising. Gastritis: inflammation or erosion of the stomach lining. Can be acute or chronic (happening frequently or most of the time). Prevention includes avoiding trigger foods, smoking, stress, alcohol, maintaining a healthy weight, and avoiding over-the-counter pain medication overuse. Acute: very serious or dangerous. Peptic Ulcer Disease: painful sores or ulcers in the stomach or small intestine lining. Prevention involves avoiding tobacco and alcohol, addressing ulcer symptoms promptly, and practicing good hygiene. The Respiratory System 🫁 Page 38  Created by Turbolearn AI What is Respiration? In single-celled organisms, oxygen diffuses into the cell, and carbon dioxide diffuses out. Larger organisms like humans require a more developed system. Breathing involves inhalation (taking in oxygen) and exhalation (removing carbon dioxide). Structural Components The respiratory system includes: nose, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, and lungs. Nose: has a large surface area, good blood supply, hair, and mucus to filter and condition inhaled air. Trachea: contains C-shaped cartilage rings to keep it open while allowing for swallowing. Alveoli: tiny air sacs where gas exchange (oxygen and carbon dioxide) occurs. Lungs: enable oxygen uptake and carbon dioxide removal; their shape is controlled by the diaphragm and intercostal muscles. Cellular respiration: combination of food and oxygen to release energy. Functions of the Respiratory System Respiration involves breathing (inhalation and exhalation) and cellular respiration (the chemical reaction of food and oxygen to release energy). Pharynx: membrane-lined cavity connecting the nose and mouth to the esophagus. Larynx: air passage to the lungs, contains vocal cords. Trachea: large tube leading to the bronchi. Bronchi: major air passages in the lungs. Bronchioles: smaller tubes branching from the bronchi. Alveoli: tiny air sacs for gas exchange. Lungs: main organs for gas exchange. Respiratory Diseases Page 39  Created by Turbolearn AI Respiratory diseases range from mild (common cold, influenza) to life-threatening (pneumonia, tuberculosis, lung cancer, COVID-19). Asthma: chronic lung disease with recurring airway obstruction, wheezing, coughing, and chest tightness. Sinusitis: painful swelling of sinus tissues. Lecture Notes: Respiratory and Circulatory Systems Respiratory System Sinusitis An inflammation of the mucous membrane lining the paranasal sinuses. It can be caused by infections, allergies, or autoimmune problems. Influenza (The Flu) A viral infection attacking the respiratory system (nose, throat, and lungs). It is distinct from stomach flu viruses causing diarrhea and vomiting. Chronic Obstructive Pulmonary Disease (COPD) 🫁 A group of diseases causing airflow blockage and breathing problems. Emphysema and chronic bronchitis are included. Smoking is a major cause. Bronchitis Inflammation of the lining of the bronchial tubes (airways to and from the lungs). Respiratory System Quiz Page 40  Created by Turbolearn AI Part I: Choose the best answer. Question Answer Which filters inhaled air? A&C Breathing through the nose is better than through: C Which is part of the respiratory organs? C A large membrane tube reinforced by cartilage is: B Millions of air sacs in the lung are called: A Part II: Short Answer 1. What are the functions of alveoli in respiration? 2. How does the human lung get oxygen and carbon dioxide? 3. List respiratory diseases and their causes. 4. Discuss the transmission of COVID-19. Circulatory System ‍ What is the Circulatory System? A system transporting substances (air, food, minerals, vitamins, liquids, and waste) between cells in an organism. Components of the Circulatory System Heart: A muscular, blood-pumping organ made of cardiac muscle. It has four chambers: Right atrium: Receives deoxygenated blood from the body; thin-walled. Left atrium: Receives oxygenated blood from the lungs. Right ventricle: Pumps deoxygenated blood to the lungs. Left ventricle: Pumps oxygenated blood throughout the body; thicker, more muscular walls. Blood vessels: Allow blood to flow from the heart to other body parts. Blood: The transport medium. Types of Blood Circulation Page 41  Created by Turbolearn AI Systematic circulation: Blood flow between the heart and the rest of the body. Pulmonary circulation: Blood flow between the heart and the lungs. Functions of the Circulatory System The circulatory system ensures that oxygenated and deoxygenated blood do not mix within the heart due to the separation of chambers by valves. Valves prevent the backflow of blood. Blood Vessels and Gas Exchange Blood Vessels There are three major types of blood vessels: arteries, veins, and capillaries. Arteries: Carry oxygenated blood away from the heart. They have thick, elastic walls to withstand the high pressure of blood pumped from the heart. The aorta is the largest artery in the body. Veins: Carry deoxygenated blood back to the heart. They have thinner walls than arteries and contain valves to prevent backflow of blood. Veins often have a lower blood pressure than arteries. Capillaries: Tiny, thin-walled vessels that connect arteries and veins. They are the sites of gas exchange (oxygen and carbon dioxide) between the blood and body tissues. Their thin walls allow for efficient diffusion. Gas Exchange in the Lungs Gas exchange primarily occurs in the alveoli of the lungs. These tiny air sacs are surrounded by a network of capillaries. The process of gas exchange relies on the principle of diffusion: gases move from areas of high concentration to areas of low concentration. In the alveoli, oxygen is high in concentration in the inhaled air and low in concentration in the blood. Oxygen therefore diffuses from the alveoli into the blood. Simultaneously, carbon dioxide, which is high in concentration in the blood, diffuses from the blood into the alveoli to be exhaled. Page 42  Created by Turbolearn AI The efficiency of gas exchange depends on several factors, including: Surface area of the alveoli Thickness of the alveolar and capillary walls Partial pressure differences of oxygen and carbon dioxide 🫁 Oxygen and Carbon Dioxide Transport Oxygen is transported in the blood primarily by binding to hemoglobin, a protein in red blood cells. Hemoglobin's structure allows it to efficiently bind to oxygen in the lungs and release it in tissues where oxygen levels are low. Carbon dioxide is transported in the blood in three ways: 1. Dissolved in plasma 2. Bound to hemoglobin 3. As bicarbonate ions (HCO − 3) The Heart's Role in Circulation The heart plays a vital role in maintaining blood flow and facilitating gas exchange. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs for oxygenation. The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body. The coordinated contractions of the heart chambers ensure efficient blood circulation. Blood and Circulation Blood Vessels Arteries: Carry oxygenated blood away from the heart (except for the pulmonary artery). Veins: Return deoxygenated blood to the heart (except for the pulmonary vein and umbilical vein). Capillaries: Connect arteries and veins; carry blood to tissues and cells. They are narrow and have thin walls. Blood Composition The blood is a fluid tissue composed of approximately 45% solids and 55% liquid (plasma). Page 43  Created by Turbolearn AI Plasma is 90% water and 10% dissolved substances such as amino acids and glucose. The solid portion consists of three types of blood cells: Size Blood Cell Type Description Function (µm) Red Blood Cells Disc-shaped, non- Transport oxygen and 6.2-8.2 (Erythrocytes) nucleated carbon dioxide White Blood Cells Colorless, irregular Protect the body from 12-17 (Leucocytes) shape, nucleated disease-causing pathogens Colorless, non- Platelets nucleated, biconvex Initiate blood clotting 2-3 (Thrombocytes) shape Major Circulatory Diseases Hypertension (High Blood Pressure): Caused by age, obesity, high salt intake, drug addiction, stress, kidney problems, diabetes, etc. Treated by reducing salt and fat intake, regular exercise, avoiding drugs, and regular checkups. Heart Attack: Blood flow to part of the heart stops, injuring the heart muscle due to lack of oxygen. Stroke: Blood supply to part of the brain is interrupted or reduced, preventing brain tissue from getting oxygen. Heart Failure: The heart muscle cannot pump enough blood to meet the body's needs for blood and oxygen. Male and Female Reproductive Organs Male Reproductive Organs The male reproductive system includes the testes, epididymis, and other structures responsible for producing and transporting sperm. Testes: Produce sperm. Epididymis: A duct extending from each testis to the urethra for sperm and fluid transportation. Sperm: A mass of male reproductive cells produced by the testes. Female Reproductive Organs Page 44  Created by Turbolearn AI The female reproductive system consists of the ovaries, vagina, uterus, fallopian tubes, cervix, clitoris, and vulva. Structure Function Ovaries Produce ova (egg cells) and sex hormones. Vagina Sexual intercourse and birth canal. Fallopian Transport eggs; site of fertilization. tubes Uterus Implantation of fertilized egg and embryo development; site of (womb) pregnancy. Ring of muscles at the uterus's lower end; opens during menstruation Cervix and childbirth. Clitoris Erectile and sensitive tissue. Vulva External female genitalia. Primary and Secondary Sexual Characteristics Primary sexual characteristics are present at birth and determine maleness or femaleness. Secondary sexual characteristics appear during puberty due to hormonal changes. Secondary Sexual Characteristics in Males Puberty in boys (usually 9-15 years old) is triggered by increased follicle- stimulating hormone (FSH) from the pituitary gland, stimulating the testes to produce testosterone. Testosterone causes: Adolescent growth spurt Growth of pubic, body, and facial hair Larynx enlargement (voice deepening) Broadening of shoulders and chest Penis enlargement; darkening of penis and scrotum skin Sperm cell production Increased muscle development Increased independence and questioning; feelings of insecurity, confusion, and anger Testosterone: Male sex hormone produced during puberty. Page 45  Created by Turbolearn AI Secondary Sexual Characteristics in Females In girls (usually 8-14 years old), FSH stimulates the ovaries to produce estrogen and progesterone. Estrogen triggers: Height and body structure development Pubic and armpit hair growth Breast development Widening of hips Voice thinning Egg maturation and menstruation onset Increased independence and questioning Estrogen and Progesterone: Female sex hormones produced during puberty. Menstruation The menstrual cycle occurs approximately every four weeks from puberty to around age 50. FSH stimulates ova development and estrogen production, causing the uterus to build a thick lining. Ovulation (egg release) occurs about 14 days before menstruation. If pregnancy doesn't occur, estrogen and progesterone levels decrease, causing the uterine lining to shed (menstruation). Menopause is the cessation of menstruation and ovulation around age 50. Menopause: Cessation of menstruation and ovulation. Ovulation: Movement of an egg from the ovary to the fallopian tube. Reproductive Health ‍ Reproductive health encompasses the physical, mental, and social well-being related to the reproductive system. Problems include female genital mutilation, early marriage, rape, illegal abortion, and sexually transmitted infections (STIs). Sexually Transmitted Diseases (STDs) STIs can be transmitted during sexual contact. Examples include: Page 46  Created by Turbolearn AI HIV/AIDS HIV (Human Immunodeficiency Virus) causes AIDS (Acquired Immune Deficiency Syndrome). There is no cure or vaccine. High-risk groups include homosexual men and women, intravenous drug users, sex workers, and hemophiliacs, as well as their sexual partners. HIV transmission occurs through breast milk, contaminated needles, unprotected sex, and mother-to-baby transmission during birth. Prevention strategies include abstinence, faithfulness to one partner, and condom use (the ABC method). Gonorrhea Caused by Neisseria gonorrhea bacteria, found in mucus membranes. Symptoms include burning urination and yellowish discharge. Early treatment with antibiotics is possible. Prevention involves the ABC method. Chancroids Caused by Hemophilus ducreyi bacteria. Symptoms include ulcers, bleeding, swollen glands, and potential penis or groin loss. Antibiotics and good sanitation are preventative measures. Syphilis Caused by Treponema pallidum bacteria. It is a very dangerous STD transmitted through unsafe sexual intercourse. Syphilis Symptoms of Syphilis The symptoms of syphilis manifest in different stages: Page 47  Created by Turbolearn AI Primary Stage: A painless sore can appear on the penis, vagina, mouth, or rectum. Secondary Stage: Symptoms include tiredness, fever, sore throat, headaches, and loss of appetite. Late Stage: Irreversible damage to the skin, bones, brain, and other organs can occur. Prevention of Syphilis Prevention methods for syphilis are similar to those for other sexually transmitted diseases. Further details on these methods were not provided in the transcript. Exercise 4.10: Part I 1. Male sex hormone produced during puberty: C. testosterone 2. Female reproductive cell: B. egg 3. Male gonad: A. testes 4. Monthly discharge of blood through the vagina: D. menstruation 5. Reproductive diseases: E. all (syphilis, gonorrhea, chancroids, HIV) Page 48