Cell Structure and Function PDF

Cell Structure and Function What is a Cell?  The cell is the basic unit of life. It is the smallest part of our body that can carry out all life functions.  Each cell is made up of 4 main parts: 1. Plasma Membrane 2. Cytoplasm 3. Organelles...

Cell Structure and Function What is a Cell?  The cell is the basic unit of life. It is the smallest part of our body that can carry out all life functions.  Each cell is made up of 4 main parts: 1. Plasma Membrane 2. Cytoplasm 3. Organelles 4. Inclusions Plasma Membrane (Cell Membrane)  What is it? Page 1 of 136  It is the outer boundary of the cell, like the cell's skin. It separates the inside of the cell from the outside environment.  Structure: The plasma membrane is made up of: 1. Phospholipids (fat molecules that form two layers) 2. Proteins (for transport, communication) 3. Cholesterol (helps stabilize the membrane) 4. Carbohydrates (help with cell recognition)  How it Works:  The plasma membrane is selectively permeable, which means it decides what goes in and out of the cell. Page 2 of 136  Small molecules like water can pass easily, but larger molecules (like proteins) cannot.  Fat-soluble substances (e.g., oxygen) pass through easily, while ions (e.g., sodium) need special channels or carriers to move across.  Main Functions: 1. Protects the cell and controls what enters or leaves. 2. Helps the cell communicate with other cells. 3. Contains receptors that recognize hormones and other signals. Cytoplasm Page 3 of 136  What is it?  The cytoplasm is the fluid inside the cell but outside the nucleus. It is where most chemical reactions happen, like building proteins and breaking down waste.  Contents:  Water (makes up 75-90% of cytoplasm)  Proteins, Carbohydrates, Lipids, and Ions  Main Functions:  It is where important processes like protein synthesis and energy production occur.  It helps with transporting materials inside the cell and removing waste. Page 4 of 136 Organelles (Mini-Organs of the Cell) These are specialized parts of the cell, each with its specific job. 1. Nucleus:  The control center of the cell. It holds the DNA (genetic material) that tells the cell how to function.  It is surrounded by a nuclear membrane with small pores that let materials in and out. 2. Ribosomes:  Small structures made of RNA.  Found on the rough endoplasmic reticulum (ER) or floating in the cytoplasm. Page 5 of 136   Their job is to make proteins, which are needed for many cell functions. 3. Endoplasmic Reticulum (ER):  A network of membranes involved in making and transporting materials.  Rough ER has ribosomes on it and helps make proteins.  Smooth ER does not have ribosomes and makes fats (lipids) and detoxifies substances. 4. Golgi Complex (Golgi Apparatus):  A stack of membranes that processes, sorts, and packages proteins and lipids made by the ER. Page 6 of 136   It prepares these materials for transport to other parts of the cell or outside the cell. 5. Mitochondria:  Known as the powerhouse of the cell.  They convert food (glucose) into energy (ATP), which the cell uses to function.  Mitochondria have a double membrane: an outer smooth membrane and an inner folded membrane, which increases the surface area for energy production. 6. Lysosomes: Page 7 of 136   Small sacs filled with enzymes that break down waste and other materials in the cell. They help with digestion inside the cell. 7. Centrosome and Centrioles:  The centrosome is a region near the nucleus that contains centrioles.  During cell division, centrioles help organize the spindle fibers that separate chromosomes. Cell Inclusions These are substances found in the cell that are not necessary for cell structure but serve specific functions. 1. Melanin – a pigment found in skin, hair, and eyes that protects from UV light. Page 8 of 136 2. Glycogen – stored in the liver and muscles, it’s a form of energy. 3. Lipids – stored in fat cells and used for energy when needed. 4. Mucus – helps in protecting and lubricating tissues, like the lining of the intestines. Cytoskeleton  What is it?  The cytoskeleton is a network of protein filaments and tubules inside the cell. It gives the cell its shape and helps with movement and transport.  Parts of the Cytoskeleton: Page 9 of 136  1. Microfilaments: Thin filaments made of protein (actin), help maintain the cell's shape. 2. Intermediate Filaments: Slightly thicker filaments that provide support and resist stress. 3. Microtubules: Hollow tubes made of protein that help with cell division and movement of materials inside the cell. Summary:  The plasma membrane is the outer boundary of the cell, controlling what enters and leaves.  The cytoplasm is the fluid where chemical reactions occur. Page 10 of 136  Organelles are specialized parts that do specific jobs to keep the cell alive and functioning.  Cytoskeleton helps the cell maintain its shape and structure. Page 11 of 136  Cell Structure: Practice Exam Quiz Multiple Choice Questions: 1. Which of the following are true regarding the plasma membrane? (Select all that apply)  A. It is selectively permeable, allowing only certain substances to enter or exit the cell.  B. It is primarily composed of phospholipids and proteins. Page 12 of 136   C. The plasma membrane is rigid and does not allow for flexibility.  D. It helps in the communication between cells and the recognition of hormones.  E. It is involved in energy production within the cell. 2. Which of the following is the primary function of mitochondria?  A. Synthesizing proteins  B. Storing genetic material  C. Producing energy in the form of ATP  D. Digesting waste materials within the cell Page 13 of 136  3. Which of the following are functions of the cytoplasm? (Select all that apply)  A. Providing structural support for the cell  B. Serving as the site for chemical reactions and synthesis of new substances  C. Containing the cell's genetic material  D. Facilitating the transport of materials within the cell  E. Maintaining the cell's shape True or False Questions: 4. True or False: The rough endoplasmic reticulum is involved in lipid production and detoxification. Page 14 of 136  5. True or False: Ribosomes are the sites of protein synthesis and can be found attached to the rough endoplasmic reticulum or floating in the cytoplasm. 6. True or False: The plasma membrane allows all substances to freely pass in and out of the cell. 7. True or False: The nucleus is the control center of the cell and contains the genetic material needed for protein synthesis. Next-Gen NCLEX Style Questions: Page 15 of 136 8. A nurse is explaining the function of the cytoskeleton to a student nurse. Which of the following functions should the nurse include in the teaching session? (Select all that apply)  A. It maintains the shape and structure of the cell.  B. It is responsible for transporting molecules across the cell membrane.  C. It assists in cell division.  D. It produces ATP for the cell.  E. It supports the cell in resisting mechanical stresses. 9. A patient has a defect in their cell's ability to produce proteins. Which of the Page 16 of 136  following organelles is most likely affected?  A. Nucleus  B. Mitochondria  C. Ribosomes  D. Golgi Complex Answers and Rationales: Multiple Choice Questions: 1. Correct Answers: A, B, D Rationale:  A: The plasma membrane is selectively permeable, allowing certain substances to pass through while blocking others.  B: The plasma membrane is mainly composed of phospholipids and proteins, with cholesterol and carbohydrates.  D: The plasma membrane helps in communication and the recognition of Page 17 of 136  hormones, nutrients, and other molecules. 2. Correct Answer: C Rationale:  Mitochondria produce ATP, the main energy source for the cell. 3. Correct Answers: B, D Rationale:  B: The cytoplasm is where many chemical reactions, including the synthesis of new molecules, occur.  D: The cytoplasm aids in transporting materials within the cell. True or False Questions: 4. Answer: False Rationale:  The smooth endoplasmic reticulum is involved in lipid production and detoxification, not the rough ER. 5. Answer: True Rationale:  Ribosomes are the sites of protein synthesis and can be found attached to the rough endoplasmic reticulum or floating in the cytoplasm. Page 18 of 136 6. Answer: False Rationale:  The plasma membrane is selectively permeable, meaning it does not allow all substances to pass freely in and out of the cell. 7. Answer: True Rationale:  The nucleus contains the genetic material needed for protein synthesis and serves as the control center of the cell. 8. Correct Answers: A, C, E Rationale:  A: The cytoskeleton helps maintain the shape and structure of the cell.  C: The cytoskeleton plays a role in organizing the cell during division.  E: The cytoskeleton helps the cell resist mechanical stresses and maintain its integrity. 9. Correct Answer: C Rationale:  Ribosomes are responsible for protein synthesis. A defect in ribosomes would Page 19 of 136 lead to an inability to produce proteins. Page 20 of 136  Introduction to Anatomy What is Anatomy?  Anatomy is the study of the structure and organization of the body and its parts.  It’s important because before understanding how things work (physiology), we first need to know what they are and how they’re put together.  Gross Anatomy: Refers to structures that are large enough to see with the naked eye (e.g., organs, muscles, bones).  Surface Anatomy: Study of the body’s surface, such as the shape and Page 21 of 136  markings visible on the skin (e.g., bone and muscle shapes).  Microscopic Anatomy (Histology): The study of structures that are too small to be seen without a microscope, such as tissues and cells. Hierarchy of Complexity (How the Body is Organized) The body is incredibly complex, and it’s organized from the smallest level to the largest level. 1. Atoms: The smallest unit of matter. (e.g., oxygen, carbon). 2. Molecules: Atoms joined together (e.g., water, proteins). Page 22 of 136 3. Organelles: Tiny components within cells that perform specific tasks (e.g., mitochondria, nucleus). 4. Cells: Basic unit of life. Each cell has a specific function (e.g., muscle cells, blood cells). 5. Tissues: Groups of similar cells working together to perform a function (e.g., muscle tissue). 6. Organs: Structures made up of different types of tissues working together to carry out specific functions (e.g., heart, kidneys). 7. Organ Systems: Groups of organs that work together for a common function (e.g., digestive system, circulatory system). Page 23 of 136 8. Organism: The complete living individual (you!). The Organ Systems of the Human Body There are 11 organ systems that work together to maintain life and health. 1. Integumentary System (Skin, hair, nails, glands)  Protects the body from the environment, helps regulate body temperature, and provides sensory information. 2. Skeletal System (Bones, cartilage, ligaments)  Provides support, protects vital organs, stores minerals, and allows movement by providing a structure for muscles. Page 24 of 136 3. Muscular System (Skeletal muscles)  Allows movement of the body and internal structures, maintains posture, and produces heat. 4. Nervous System (Brain, spinal cord, nerves)  Controls body functions through electrical signals, processes sensory information, and helps with memory, learning, and decision-making. 5. Endocrine System (Glands like thyroid, pituitary, and adrenal glands)  Regulates body functions using hormones, such as growth, metabolism, and mood. Page 25 of 136 6. Circulatory System (Heart, blood vessels, blood)  Delivers oxygen and nutrients to tissues, removes waste, and helps in immune defense. 7. Lymphatic System (Lymph nodes, lymphatic vessels, spleen, thymus, tonsils)  Defends the body against disease, helps fluid balance, and absorbs fats from the digestive system. 8. Respiratory System (Lungs, trachea, bronchi, nose)  Facilitates gas exchange (oxygen and carbon dioxide) between the body and the environment. Page 26 of 136 9. Digestive System (Mouth, esophagus, stomach, intestines, liver, pancreas, gallbladder)  Breaks down food into absorbable nutrients for energy, growth, and cell repair. 10. Urinary System (Kidneys, bladder, ureters, urethra)  Removes waste and excess water from the blood to maintain fluid and electrolyte balance. 11. Reproductive System (Ovaries, testes, uterus, prostate, etc.)  Responsible for producing offspring, including the formation of eggs and sperm. Page 27 of 136 The Anatomical Position The anatomical position is the standard reference position used in describing the body and its parts.  Standing upright, facing forward.  Feet flat and slightly apart.  Arms at the sides, with palms facing forward. This position ensures clear descriptions when referring to parts of the body (e.g., "the wrist is distal to the elbow"). Directional Terms These terms help describe locations of structures in the body Term Meaning Superior Toward the head (higher) Page 28 of 136  Inferior Toward the feet (lower) Anterior Toward the front of the body Posterior Toward the back of the body Medial Toward the midline of the body Lateral Away from the midline of the body Proximal Closer to the point of attachment (e.g., shoulder) Distal Farther from the point of attachment (e.g., hand) Superficial Closer to the surface Deep Away from the surface Body Planes and Sections Page 29 of 136  Planes divide the body into sections. These planes help in describing cuts or views of the body during study or medical procedures. 1. Sagittal Plane (Divides body into left and right halves)  If the halves are equal, it’s called midsagittal. 2. Frontal (Coronal) Plane (Divides body into front and back parts) 3. Transverse (Cross) Plane (Divides body into top and bottom parts) These sections are important in medical imaging (e.g., CT scans, MRIs). Body Cavities & Membranes Page 30 of 136  The body contains large spaces called cavities that house and protect internal organs. 1. Dorsal Body Cavity (Back side of the body)  Cranial Cavity: Holds the brain.  Vertebral Cavity: Holds the spinal cord.  Lined by meninges (protective membranes). 2. Ventral Body Cavity (Front side of the body)  Thoracic Cavity: Holds the heart and lungs.  Abdominopelvic Cavity: Holds the digestive organs, urinary organs, and reproductive organs.  These cavities are lined by serous membranes: Page 31 of 136   Pleura (lungs)  Pericardium (heart)  Peritoneum (abdomen) Summary  Anatomy is the study of the structure of the body, and it is crucial for understanding how the body works.  The body is made up of atoms, molecules, cells, tissues, organs, organ systems, and finally, the whole organism.  There are 11 organ systems that each have specific functions essential for survival.  Directional terms and anatomical positions are vital to understanding and describing the body. Page 32 of 136  Planes and sections help describe how we "cut" or look at the body for study and treatment.  Cavities protect vital organs and are lined by membranes that help with organ protection and function. Page 33 of 136 1. Multiple Choice What is the study of the structure of tissues under a microscope called? A) Gross anatomy B) Histology C) Surface anatomy D) Microscopic anatomy 2. Multiple Choice Which of the following is an example of an organ system in the human body? A) Blood vessels B) Brain C) Nervous system D) Ligaments Page 34 of 136 3. True or False The anatomical position is when the body is lying down on its side with the arms extended. A) True B) False 4. Multiple Choice Which of the following directional terms refers to a structure that is closer to the surface of the body? A) Superficial B) Deep C) Medial D) Proximal Page 35 of 136 5. Select All that Apply Which of the following are components of the integumentary system? (Select all that apply) A) Skin B) Hair C) Nails D) Spleen E) Cutaneous glands 6. Multiple Choice Which body plane divides the body into anterior and posterior parts? A) Sagittal plane B) Transverse plane C) Frontal (coronal) plane D) Midsagittal plane Page 36 of 136 7. True or False The dorsal body cavity contains the heart and lungs. A) True B) False 8. Multiple Choice Which organ system is primarily responsible for transporting oxygen, nutrients, and waste products throughout the body? A) Nervous system B) Endocrine system C) Circulatory system D) Muscular system Page 37 of 136 9. Select All that Apply Which of the following are examples of body cavities? (Select all that apply) A) Cranial cavity B) Vertebral cavity C) Abdominopelvic cavity D) Thoracic cavity E) Parietal cavity 10. True or False Proximal refers to a part of the body that is farther from the trunk. A) True B) False Answer Key and Rationales: Page 38 of 136 1. B) Histology  Rationale: Histology is the study of tissues at a microscopic level. Gross anatomy involves larger structures visible to the naked eye. 2. C) Nervous system  Rationale: The nervous system is an organ system that consists of the brain, spinal cord, and nerves working together to control and regulate body functions. 3. B) False  Rationale: The anatomical position refers to the body standing upright, facing forward with arms at the sides and palms facing forward. It does not involve lying down. Page 39 of 136 4. A) Superficial  Rationale: Superficial refers to a structure that is closer to the surface of the body, whereas deep refers to structures further from the surface. 5. A) Skin, B) Hair, C) Nails, E) Cutaneous glands  Rationale: The integumentary system includes the skin, hair, nails, and glands like sweat and sebaceous glands. The spleen is part of the lymphatic system, not the integumentary system. 6. C) Frontal (coronal) plane  Rationale: The frontal or coronal plane divides the body into anterior (front) and posterior (back) sections. The sagittal Page 40 of 136  plane divides the body into left and right halves. 7. B) False  Rationale: The dorsal body cavity includes the cranial cavity (brain) and vertebral cavity (spinal cord). The heart and lungs are located in the ventral cavity. 8. C) Circulatory system  Rationale: The circulatory system, which includes the heart and blood vessels, is responsible for transporting oxygen, nutrients, and waste products throughout the body. 9. A) Cranial cavity, B) Vertebral cavity, C) Abdominopelvic cavity, D) Thoracic cavity Page 41 of 136   Rationale: These are all examples of body cavities. The parietal cavity is not a recognized body cavity. 10. B) False  Rationale: Proximal refers to being closer to the trunk or attachment point of a limb. Distal, not proximal, refers to being farther from the trunk. Page 42 of 136  What is Physiology? Physiology is the study of the functional mechanisms of living organisms. It involves understanding the processes that enable the body to carry out various activities, from breathing to digesting food, and maintaining balance within the body.  Key Concept: Physiology looks at how systems of the body work together to keep us alive and healthy. For example, how the heart pumps blood, how muscles contract, or how the brain processes information. Examples in Physiology: 1. Homeostasis: The process by which the body maintains stable internal conditions Page 43 of 136  (like temperature, blood pressure, and glucose levels) despite changes in the external environment. 2. Reactivity: How organisms respond to environmental changes. For instance, the body reacts to a hot environment by sweating to cool down. Basic Life Processes The six life processes distinguish living organisms from non-living things. These processes include: 1. Metabolism  Metabolism is the sum of all chemical reactions in the body that sustain life. Page 44 of 136   It involves two types of reactions:  Anabolism: Building complex molecules from simpler ones (e.g., protein synthesis for muscle growth).  Catabolism: Breaking down large molecules to release energy (e.g., breaking down glucose to produce ATP).  The energy produced is used to power cellular functions like movement, growth, and repair. 2. Responsiveness (Excitability)  Excitability refers to the ability of an organism to sense changes in its environment and respond to those changes. Page 45 of 136   For example:  Nerve cells detect stimuli (e.g., pain) and send electrical signals to the brain.  Muscle cells contract in response to nerve signals, causing movement.  Conductivity: The ability to carry electrical impulses from one part of the cell to another.  Contractility: The ability of muscles to shorten and generate force, allowing movement (e.g., heart muscle contraction to pump blood). 3. Movement Page 46 of 136   Movement includes the motion of the whole body, individual organs, cells, and even tiny structures inside cells (like organelles).  For movement to happen, coordination is needed to make sure different body parts work together.  Example: Muscles contract in coordination with nerves to allow you to walk. 4. Growth  Growth involves increasing cell size and number of cells. Page 47 of 136   Example: Muscle cells increase in size after exercise, leading to muscle growth.  Growth can also occur when more material accumulates between cells (e.g., bone growth due to calcium deposition). 5. Differentiation  Differentiation is when unspecialized cells (like stem cells) become specialized with specific functions.  Example: A stem cell in the bone marrow differentiates into a red or white blood cell. Page 48 of 136   Another example: A fertilized egg divides and differentiates into a complex organism with specialized cells and tissues. 6. Reproduction  Reproduction involves producing new cells for growth and repair or creating a new individual.  Cell Division (Mitosis) is essential for tissue repair, while Meiosis is involved in sexual reproduction (e.g., creating eggs and sperm). Homeostasis: The Body’s Internal Balance Page 49 of 136 Homeostasis is the body’s ability to maintain a stable internal environment, which is essential for survival. The internal environment includes things like oxygen, glucose, water, and ions (sodium, potassium) that need to be kept at optimal levels.  Key Systems for Homeostasis:  Lungs: Provide oxygen and remove carbon dioxide.  Kidneys: Maintain proper ion balance and remove waste.  Digestive System: Absorbs nutrients for energy and growth. Body Fluids and Their Importance Page 50 of 136 The body is made up of different types of fluids, each serving a critical function in maintaining homeostasis: 1. Total Body Water (TBW): Comprises about 60% of body weight, and is divided into two compartments:  Intracellular Fluid (ICF): Fluid inside the cells (about 66% of TBW).  Extracellular Fluid (ECF): Fluid outside the cells (about 33% of TBW). 2. Types of Extracellular Fluid (ECF):  Interstitial Fluid: The fluid that surrounds cells. Page 51 of 136  Blood Plasma: The fluid part of blood that carries nutrients, gases, and waste products.  Lymph: Fluid found in lymphatic vessels, which helps with immune responses.  Cerebrospinal Fluid: Fluid surrounding the brain and spinal cord for protection.  Synovial Fluid: Fluid in joints that reduces friction.  Aqueous Humour: Fluid in the eyes that helps maintain eye pressure. Page 52 of 136 Control of Homeostasis: Feedback Systems The body uses feedback systems to keep internal conditions stable. These systems include: 1. Controlled Condition: What is being monitored, such as blood glucose or body temperature. 2. Stimulus: A change in the controlled condition (e.g., a rise in temperature or blood glucose). 3. Receptors: Structures (like sensors) that detect changes and send signals to the control center. 4. Control Center: Usually the brain, which evaluates the information and determines the response. Page 53 of 136  5. Effectors: Structures (like muscles or glands) that carry out the response to restore balance. Types of Feedback: 1. Negative Feedback: The most common type, where the response reverses the change to bring the condition back to normal.  Example: Blood pressure regulation:  If blood pressure rises, sensors in the blood vessels detect this and send signals to the brain.  The brain then sends signals to the heart to slow down and to blood Page 54 of 136  vessels to dilate, lowering blood pressure. 2. Positive Feedback: Less common, where the response amplifies the change.  Example: Childbirth:  During labor, the hormone oxytocin increases contractions, which leads to more oxytocin release, making contractions stronger and helping to push the baby out. Electrolytes in Body Fluids Electrolytes are substances that carry an electric charge when dissolved in water. They are critical for maintaining fluid balance, Page 55 of 136 transmitting nerve signals, and muscle contractions.  Sodium (Na+): Found in high concentrations in the extracellular fluid (ECF). Helps regulate fluid balance and blood pressure.  Potassium (K+): Found in high concentrations in intracellular fluid (ICF). Essential for nerve function and muscle contractions.  Calcium (Ca2+): Plays a key role in muscle contraction, blood clotting, and bone health.  Magnesium (Mg2+): Involved in enzyme reactions and muscle function. Page 56 of 136   Chloride (Cl-): Works with sodium to maintain fluid balance and is important in maintaining the acid-base balance. Summary of Key Concepts  Physiology: Focuses on understanding how the body functions and maintains life.  Life Processes: Metabolism, responsiveness, movement, growth, differentiation, and reproduction are the key processes that define living organisms.  Homeostasis: The body’s ability to maintain internal balance despite external changes.  Body Fluids: Vital for the body’s function, with intracellular and extracellular compartments. Page 57 of 136  Feedback Systems: Control mechanisms that help maintain homeostasis, using negative or positive feedback to regulate body conditions.  Electrolytes: Substances in body fluids that help regulate various physiological processes, including nerve and muscle function. Exam: Physiology and Homeostasis Page 58 of 136 Multiple Choice Questions 1. Which of the following processes is characterized by the breakdown of complex molecules into simpler ones to release energy?  A) Anabolism  B) Metabolism  C) Catabolism  D) Differentiation 2. What is the primary function of homeostasis in the human body?  A) Maintain a constant body temperature  B) Maintain stable internal conditions despite changes in the external environment  C) Increase cell size and number  D) Regulate hormonal secretion Page 59 of 136 3. Which of the following is an example of positive feedback in the human body?  A) Regulation of blood pressure by the heart  B) Oxytocin release during childbirth  C) Decrease in blood glucose after eating  D) Regulation of sodium levels in the kidneys 4. Which of the following statements about intracellular fluid (ICF) is correct?  A) It makes up about 33% of total body water.  B) It contains a higher concentration of sodium than extracellular fluid.  C) It is located inside cells and constitutes 66% of total body water.  D) It is mainly composed of plasma proteins and fat. Page 60 of 136  5. The primary role of the nervous system in homeostasis is to:  A) Regulate hormone levels.  B) Monitor and respond to environmental changes by sending nerve impulses.  C) Control muscle contractions in response to stress.  D) Break down nutrients into energy. Select All That Apply 6. Which of the following are considered life processes in physiology? (Select all that apply)  A) Metabolism  B) Growth  C) Circulation  D) Differentiation  E) Reproduction Page 61 of 136  7. Which of the following are types of extracellular fluid (ECF)? (Select all that apply)  A) Interstitial fluid  B) Blood plasma  C) Cerebrospinal fluid  D) Lymph  E) Intracellular fluid 8. Which of the following are functions of electrolytes in body fluids? (Select all that apply)  A) Regulation of fluid balance  B) Maintenance of muscle contractions  C) Facilitation of protein synthesis  D) Transmission of nerve impulses  E) Regulation of blood sugar levels True or False Page 62 of 136 9. True or False: Anabolism involves the breakdown of large molecules into simpler ones.  A) True  B) False 10. True or False: Negative feedback systems work to counteract changes and bring the body back to a normal range.  A) True  B) False 11. True or False: Stem cells are undifferentiated cells that can develop into specialized cells with specific functions.  A) True  B) False 12. True or False: Homeostasis refers only to the regulation of blood pressure. Page 63 of 136   A) True  B) False 13. True or False: Potassium is found in higher concentrations in extracellular fluid (ECF) compared to intracellular fluid (ICF).  A) True  B) False Answer Key with Rationales 1. C) Catabolism  Rationale: Catabolism refers to the breakdown of larger molecules into smaller ones, releasing energy. Anabolism, on the other hand, involves building larger molecules from smaller ones. 2. B) Maintain stable internal conditions despite changes in the external environment Page 64 of 136   Rationale: Homeostasis is the body's ability to regulate internal conditions (like temperature, pH, and glucose levels) to stay within a stable range despite external fluctuations. 3. B) Oxytocin release during childbirth  Rationale: Positive feedback amplifies a change. During childbirth, the release of oxytocin increases contractions, which in turn stimulates more oxytocin release, leading to stronger contractions until delivery occurs. 4. C) It is located inside cells and constitutes 66% of total body water  Rationale: Intracellular fluid (ICF) is the fluid inside the cells and makes up about 66% of total body water. It is important for maintaining cellular function. 5. B) Monitor and respond to environmental changes by sending nerve impulses Page 65 of 136   Rationale: The nervous system is responsible for detecting changes (stimuli) and sending electrical signals (nerve impulses) to the control center to initiate a response, helping maintain homeostasis. Select All That Apply Answers 6. A) Metabolism, B) Growth, D) Differentiation, E) Reproduction  Rationale: These are all fundamental life processes. Circulation is a physiological function, but not a distinct life process. 7. A) Interstitial fluid, B) Blood plasma, C) Cerebrospinal fluid, D) Lymph  Rationale: These are all types of extracellular fluid. Intracellular fluid (ICF) is found inside cells, not in the extracellular compartment. Page 66 of 136  8. A) Regulation of fluid balance, B) Maintenance of muscle contractions, D) Transmission of nerve impulses  Rationale: Electrolytes (like sodium, potassium, calcium, and chloride) play key roles in fluid balance, muscle contractions, and nerve signaling. Protein synthesis and blood sugar regulation are not directly influenced by electrolytes. True or False Answers 9. B) False  Rationale: Anabolism involves the building up of molecules, not the breakdown. Catabolism is the process that breaks down larger molecules. 10. A) True  Rationale: Negative feedback systems work to oppose changes in the body to maintain a stable internal environment, Page 67 of 136  such as regulating blood pressure or body temperature. 11. A) True  Rationale: Stem cells are unspecialized cells that have the potential to differentiate into various specialized cell types with specific functions. 12. B) False  Rationale: Homeostasis refers to the regulation of multiple internal conditions, such as temperature, pH, glucose levels, etc., not just blood pressure. 13. B) False  Rationale: Potassium is found in higher concentrations in intracellular fluid (ICF), while sodium is more concentrated in extracellular fluid (ECF). Page 68 of 136  The Chemical Level of Organization The chemical level is where life begins. At this level, everything is made up of atoms and molecules that combine to form the building blocks of cells, tissues, organs, and systems. Hierarchy of Complexity The human body is organized in a hierarchical way, from simple to complex: 1. Chemical Level – Atoms and molecules. 2. Cellular Level – Cells, which are the basic units of life. 3. Tissue Level – Groups of similar cells working together. Page 69 of 136 4. Organ Level – Different tissues working together to perform specific functions. 5. System Level – Different organs working together (e.g., digestive system). 6. Organism Level – The entire body, functioning as one. Chemical Elements in the Body The body contains about 26 elements. Of these, only a few are essential for life, making up the majority of your body weight:  Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N): These elements account for 96% of body weight. Page 70 of 136  Calcium (Ca) and Phosphorus (P): These account for 3% of body weight.  Trace elements (e.g., iron, zinc, iodine, etc.): These make up the remaining 1%, but they are still crucial for various biological processes. Atoms: The Building Blocks of Matter An atom is the smallest unit of an element. It is made up of three basic particles:  Protons: Positively charged particles in the nucleus (center of the atom).  Neutrons: Particles with no charge, also located in the nucleus. Page 71 of 136   Electrons: Negatively charged particles that orbit the nucleus. The number of protons determines what element the atom is. For example, if an atom has 6 protons, it is carbon (C).  Atomic Number: The number of protons in an atom’s nucleus (this defines the element).  Atomic Weight: The combined number of protons and neutrons in an atom. Chemical Compounds in the Body The body is made up of chemical compounds— groups of 2 or more atoms bonded together. There are 2 types of chemical compounds: Page 72 of 136  1. Inorganic Compounds  Inorganic compounds usually do not contain carbon. They tend to be small molecules that are ionically bonded (meaning the atoms have electrical charges).  Examples of inorganic compounds:  Water (H₂O): Makes up about 60-70% of body weight. Water is the universal solvent, meaning many substances can dissolve in it. It plays an essential role in chemical reactions and temperature regulation.  Salts: Made when an acid reacts with a base (e.g., sodium chloride (NaCl) is table salt). Salts help maintain proper fluid balance and conduct electrical signals in the body. Page 73 of 136   Acids: Substances that release H⁺ ions in water (e.g., hydrochloric acid (HCl) in the stomach).  Bases: Substances that release OH⁻ ions (e.g., sodium hydroxide (NaOH)). 2. Organic Compounds  Organic compounds contain carbon and hydrogen. These are usually large molecules that are covalently bonded (meaning the atoms share electrons).  Examples of organic compounds:  Carbohydrates: Include sugars and starches. They are made up of carbon (C), hydrogen (H), Page 74 of 136  and oxygen (O). The main function of carbohydrates is to provide energy.  Monosaccharides: Simple sugars like glucose. Glucose is the main energy source for cells.  Disaccharides: Two monosaccharides joined together (e.g., sucrose, made from glucose + fructose).  Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen). Glycogen is the storage form of glucose in the liver and muscles.  Lipids (Fats): Composed of carbon, hydrogen, and oxygen. Lipids are insoluble in water and serve as energy storage, insulation, and protection for organs. Page 75 of 136   Saturated fats: Found in animal products and solid at room temperature (e.g., butter).  Unsaturated fats: Found in plant oils and are liquid at room temperature (e.g., olive oil).  Phospholipids: Make up the cell membrane.  Steroids: Include cholesterol, which is important for cell membrane structure and hormone production.  Proteins: Made up of amino acids. Proteins are involved in many body functions, such as muscle contraction, enzyme reactions, and immune response. Page 76 of 136   Amino acids are the building blocks of proteins. There are 20 different amino acids that combine in various sequences to form different proteins.  Nucleic Acids: Includes DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid).  DNA stores genetic information. It is made up of nucleotides, which contain a sugar (deoxyribose), a phosphate group, and nitrogen bases (adenine, thymine, cytosine, guanine).  RNA helps with protein synthesis. It is single-stranded and uses ribose as its sugar and uracil (U) instead of thymine (T). Page 77 of 136  Adenosine Triphosphate (ATP): The energy currency of the body. ATP is used for all cell activities, such as muscle contraction, nerve signaling, and active transport (moving substances in and out of cells). It consists of:  Adenosine (a nitrogenous base + ribose)  Three phosphate groups.  When one of the phosphate bonds breaks, energy is released (ATP → ADP + P + energy). Water: The Body’s Essential Liquid Page 78 of 136  Water is the most important inorganic compound in the body. It makes up about 60- 70% of your body weight.  Functions of water:  Solvent: It dissolves many substances, allowing them to be transported through the body.  Temperature regulation: Water absorbs heat and helps keep the body temperature stable.  Chemical reactions: Water participates in many important reactions inside cells.  Lubrication: It is found in joints and around organs to reduce friction. Page 79 of 136 Acids, Bases, and pH Balance  Acids release H⁺ ions when dissolved in water.  Example: Hydrochloric acid (HCl) dissociates into H⁺ and Cl⁻ ions.  Bases release OH⁻ ions in water.  Example: Sodium hydroxide (NaOH) dissociates into Na⁺ and OH⁻ ions.  pH scale: Measures the acidity or alkalinity of a solution.  pH 7 = neutral (e.g., pure water).  pH < 7 = acidic (more H⁺ ions).  pH > 7 = basic (more OH⁻ ions). Page 80 of 136  Buffer Systems: Help maintain a stable pH by neutralizing excess acids or bases. For example, the carbonic acid-bicarbonate buffer system in the blood helps maintain pH around 7.4. Summary  The chemical level of organization includes atoms, molecules, and compounds.  Inorganic compounds (like water, salts, and acids) are important for functions like maintaining pH and temperature.  Organic compounds (like carbohydrates, lipids, proteins, nucleic acids) play key Page 81 of 136  roles in energy production, storage, and biological functions.  ATP is the energy currency of cells.  Water is crucial for life, helping with chemical reactions, temperature regulation, and lubrication. Page 82 of 136  Chemical Level of Organizations: Practice Questions 1. Multiple Choice Which of the following statements is true regarding the role of water in the body? A. Water is a poor solvent for most substances in the body. B. Water helps regulate body temperature by Page 83 of 136 absorbing and releasing heat slowly. C. Water is not involved in chemical reactions. D. Water only functions as a lubricant in joints. 2. Select All That Apply Which of the following are inorganic compounds that play essential roles in the body? (Select all that apply.) A. Water B. Proteins C. Acids D. Phospholipids E. Salts 3. Multiple Choice Page 84 of 136 Which of the following molecules are considered organic compounds? A. Water B. Salts C. Carbohydrates D. Oxygen 4. True or False An atom's atomic number is the sum of the number of protons and neutrons in the nucleus of the atom. A. True B. False 5. Multiple Choice Page 85 of 136 What is the primary function of glycogen in the human body? A. It provides a source of long-term energy storage. B. It helps in the formation of amino acids. C. It is the storage form of glucose. D. It is used for the synthesis of ATP. 6. Select All That Apply Which of the following are true about acids? (Select all that apply.) A. Acids release H⁺ ions when dissolved in water. B. Acids increase the pH of a solution. C. Acids are always neutral in nature. Page 86 of 136 D. Hydrochloric acid (HCl) is an example of an acid. 7. Multiple Choice Which of the following is a function of ATP in the body? A. It stores genetic information. B. It is used for the transport of substances through the cell membrane. C. It synthesizes proteins for the body. D. It acts as a buffer to maintain pH balance in the blood. 8. True or False Phospholipids are primarily involved in energy storage and are a type of lipid. Page 87 of 136 A. True B. False 9. Multiple Choice What is the difference between saturated fats and unsaturated fats? A. Saturated fats contain one or more double bonds between carbon atoms. B. Unsaturated fats contain no double bonds between carbon atoms. C. Saturated fats are typically liquid at room temperature. D. Unsaturated fats are typically liquid at room temperature. Page 88 of 136 10. Select All That Apply Which of the following statements are true about buffers in the body? (Select all that apply.) A. Buffers help maintain a stable pH by neutralizing excess acids or bases. B. The buffer system only works when the pH is acidic. C. The carbonic acid-bicarbonate buffer system is an example of a buffer. D. Buffers work by directly removing H⁺ ions from the blood. Page 89 of 136  Answers and Rationales 1. Answer: B Page 90 of 136 Rationale: Water regulates body temperature by absorbing and releasing heat slowly, which helps maintain homeostasis. It is a good solvent and is involved in many chemical reactions, including those that sustain life. 2. Answer: A, C, E Rationale: Water, acids, and salts are inorganic compounds that are vital for various bodily functions. Proteins and phospholipids are organic compounds that contain carbon and hydrogen. 3. Answer: C Rationale: Carbohydrates are organic compounds, meaning they contain carbon and hydrogen. Page 91 of 136 Water, salts, and oxygen are inorganic compounds. 4. Answer: B Rationale: The atomic number is the number of protons in an atom, not the sum of protons and neutrons. The sum of protons and neutrons is the atomic weight. 5. Answer: C Rationale: Glycogen is the storage form of glucose in the body, stored in the liver and muscles. It is broken down into glucose when the body needs energy. 6. Answer: A, D Page 92 of 136 Rationale: Acids release H⁺ ions when dissolved in water, which makes the solution more acidic. Hydrochloric acid (HCl) is an example of an acid. Acids decrease the pH of a solution, not increase it, and they are not neutral. 7. Answer: B Rationale: ATP is used for energy in many cellular processes, including the transport of substances across the cell membrane, protein synthesis, and mechanical work. ATP is not involved in storing genetic information. 8. Answer: B Rationale: Phospholipids are involved in forming the cell membrane, not energy storage. Page 93 of 136 They are a type of lipid that plays a key role in cell structure and function. 9. Answer: D Rationale: Saturated fats have no double bonds between their carbon atoms, making them saturated with hydrogen atoms. They are solid at room temperature (e.g., butter). Unsaturated fats contain one or more double bonds, making them liquid at room temperature (e.g., olive oil). 10. Answer: A, C Rationale: Buffers help maintain a stable pH by neutralizing excess acids or bases. The carbonic acid-bicarbonate buffer system is a key example of this process. Buffers don’t Page 94 of 136 remove H⁺ ions directly; they balance the pH by converting strong acids and bases into weaker ones. Page 95 of 136  Tissue Level of Organization Tissues  A tissue is a group of similar cells that work together to perform a specialized function.  These tissues are often surrounded by a small amount of extracellular material, such as the matrix, which is a mixture of proteins, water, and other molecules. 4 Major Tissue Types The body has four main types of tissue, each with its own specialized function: a) Epithelial Tissue Page 96 of 136   Function: Covers and lines body surfaces, cavities, and organs. It also forms glands.  Subtypes: 1. Covering and Lining Epithelium:  Lines body cavities, respiratory and digestive tracts, blood vessels, and ducts.  Forms the outer layer of the body and some internal organs.  Specialized for absorption, filtration, and protection. 2. Glandular Epithelium: Page 97 of 136  Forms the secretory portions of glands, such as sweat glands, salivary glands, and endocrine glands.  Secretes substances like mucus, enzymes, and hormones. b) Connective Tissue  Function: Provides support and structure to the body, stores energy, and transports nutrients.  Examples: Bone, blood, cartilage, and adipose tissue. c) Muscle Tissue Page 98 of 136   Function:  Responsible for movement through contraction.  Types:  Skeletal muscle (voluntary movement)  Cardiac muscle (heart contraction)  Smooth muscle (involuntary movement in organs) d) Nervous Tissue  Function: Transmits electrical signals and coordinates body activities. Page 99 of 136  Components: Neurons (nerve cells) and glial cells (supporting cells). Epithelial Tissue: Detailed Explanation General Characteristics of Epithelial Tissue:  Closely Packed Cells: The cells are tightly packed with minimal intercellular space, meaning they form continuous sheets.  Avascular: Epithelial tissue has no blood vessels; it gets nutrients and removes waste via the underlying connective tissue.  Basement Membrane: Epithelial cells are attached to the underlying connective tissue by a thin layer called the basement membrane. Page 100 of 136  Regeneration: Epithelial cells regenerate quickly, especially in areas exposed to wear and tear (like skin). Types of Epithelial Tissue Based on Arrangement 1. Simple Epithelium: One layer of cells. Found where absorption, secretion, or filtration occurs (e.g., lungs, kidneys). 2. Stratified Epithelium: Multiple layers of cells. Found in areas subjected to abrasion (e.g., skin, esophagus). 3. Pseudostratified Epithelium: Appears to have multiple layers but actually only one layer of cells. Found in parts of the respiratory system and male reproductive ducts. Page 101 of 136 Types of Epithelial Tissue Based on Cell Shape 1. Squamous: Flat and scale-like. Found where diffusion or filtration happens (e.g., air sacs in the lungs). 2. Cuboidal: Cube-shaped cells, often involved in secretion or absorption (e.g., kidney tubules). 3. Columnar: Tall and rectangular, often involved in secretion and absorption (e.g., digestive tract). 4. Transitional: Cells that can change shape depending on stretch. Found in organs like the urinary bladder. Special Types of Epithelial Tissue Page 102 of 136 Simple Squamous Epithelium  Structure: A single layer of flat cells.  Function: Allows for easy diffusion, osmosis, and filtration.  Locations:  Lungs: For gas exchange.  Kidneys: For filtration.  Blood vessels and lymphatic vessels: Known as endothelium. Simple Cuboidal Epithelium  Structure: A single layer of cube-shaped cells. Page 103 of 136  Function: Secretion and absorption.  Locations:  Kidney tubules: For water reabsorption.  Ovaries: Covers the surface of ovaries.  Glands: Lines ducts of some glands like thyroid and salivary glands. Simple Columnar Epithelium  Structure: A single layer of tall, column- like cells. Can be ciliated or non-ciliated.  Function: Protection, absorption, and secretion.  Locations: Page 104 of 136   Non-ciliated: Lines most of the digestive tract, gallbladder, and excretory ducts.  Ciliated: Found in the upper respiratory tract, uterine tubes, and some areas of the spinal cord. Stratified Squamous Epithelium  Structure: Multiple layers of cells. The surface layer is flat and the deeper layers are more cuboidal or columnar.  Function: Protection from abrasion and infection.  Locations: Page 105 of 136   Keratinized: Skin (the surface layer contains keratin).  Non-keratinized: Mouth, esophagus, and vagina. Transitional Epithelium  Structure: Multiple layers of cells that can stretch and change shape.  Function: Allows for stretching and distension.  Locations:  Urinary bladder: Prevents organ rupture when stretched. Page 106 of 136 Glandular Epithelium  Function: Secretes substances such as hormones, enzymes, or mucus.  Exocrine Glands:  Secrete products into ducts that empty on body surfaces (e.g., sweat glands, salivary glands).  Endocrine Glands:  Secrete products (hormones) directly into the bloodstream (e.g., thyroid, pituitary glands). Glandular Secretion Types  Exocrine Glands: Page 107 of 136 1. Holocrine: Glands where the cell bursts to release secretion (e.g., sebaceous glands). 2. Merocrine: Glands that secrete products without losing any cellular material (e.g., salivary glands, pancreas). 3. Apocrine: Glands that secrete by pinching off part of the cell (e.g., mammary glands). Key Points to Remember 1. Epithelial Tissue: Protects, absorbs, secretes, and filters. 2. Stratified vs. Simple Epithelium: Stratified protects against wear and tear; simple is for absorption and filtration. Page 108 of 136 3. Squamous, Cuboidal, Columnar, Transitional: These describe the shape of the epithelial cells and their specialized functions. 4. Glandular Epithelium: Secretes substances into ducts or the blood (exocrine vs. endocrine glands). Connective Tissue: Definition and General Features  Definition: Connective tissue is one of the four main types of tissue in the body (along with epithelial, muscle, and nervous tissues). It’s designed to bind, support, protect, and connect various structures in the body. It is the most abundant tissue type in the body.  Characteristics: Page 109 of 136  Cells: Unlike epithelial tissue, which has cells closely packed, connective tissue cells are widely scattered.  Matrix: Connective tissues have a significant amount of intercellular material (matrix), which is composed of fibers (collagen, elastic, reticular) and ground substance (fluid, semifluid, or solid material).  Vascularity: Most connective tissues are highly vascular (rich in blood supply), but cartilage is an exception as it is avascular (no blood vessels).  Location: Connective tissue is not found on body surfaces (e.g., it doesn’t form the outer lining of the body or body cavities). Page 110 of 136 Main Functions of Connective Tissue 1. Support: Forms the framework for body structures (e.g., bones, cartilage). 2. Protection: Protects organs, especially internal ones (e.g., ribcage protects the heart and lungs). 3. Binding: Binds tissues and organs together, helping them stay in place (e.g., tendons binding muscle to bone, ligaments binding bone to bone). 4. Storage: Stores essential substances like fat (for energy) and minerals (such as calcium in bones). Page 111 of 136 5. Transport: Blood transports oxygen, nutrients, and waste products throughout the body. 6. Immunity: Contains cells (e.g., macrophages, plasma cells) that help defend against pathogens. Connective Tissue Components 1. Cells:  Fibroblasts: Produce fibers (collagen, elastic) and ground substance. They are essential in tissue repair.  Macrophages: Specialized in phagocytosis (engulfing bacteria and debris). They are crucial for immune defense. Page 112 of 136  Plasma Cells: Derive from B lymphocytes (white blood cells) and produce antibodies, crucial for immune defense.  Mast Cells: Contain granules that release histamine (which promotes inflammation) and heparin (an anticoagulant that prevents blood clotting).  Adipocytes (Fat Cells): Store fat for energy and act as insulation.  Leukocytes (White Blood Cells): Help in immune response by combating infection. 2. Matrix: This non-living substance gives connective tissue its functional properties. Page 113 of 136  Ground Substance: A fluid or gel-like substance where the cells and fibers are embedded. It can be:  Fluid (in blood plasma),  Semifluid (in loose connective tissue),  Solid (in bone).  Fibers:  Collagen Fibers: Provide strength and resistance to pulling forces. They are tough and flexible.  Elastic Fibers: Made of elastin, these fibers give tissues the ability to stretch and recoil. Page 114 of 136   Reticular Fibers: Thin fibers made of collagen and glycoproteins that form a supporting mesh (stroma) in soft organs like the liver, spleen, and lymph nodes. Types of Connective Tissue Embryonic Connective Tissue 1. Mesenchyme:  Found exclusively in the embryo, it is the precursor to all other connective tissues.  Cells are star-shaped and embedded in a fluid-like matrix.  As the embryo develops, mesenchymal cells differentiate into other types of connective tissue. Page 115 of 136 2. Mucous Connective Tissue (Wharton’s Jelly):  Found primarily in the umbilical cord of the fetus.  Contains a gelatinous matrix that supports the umbilical cord and helps protect the fetus. Adult Connective Tissue 1. Connective Tissue Proper:  Has a fibrous matrix and is classified into:  Loose Connective Tissue: Flexible and provides cushioning (e.g., areolar tissue). Page 116 of 136  Dense Connective Tissue: Strong and provides resistance to stress (e.g., tendons, ligaments).  Types:  Loose (Areolar) Connective Tissue:  Most widespread type, found beneath epithelial tissues and around organs.  Fibers: Collagenous, elastic, and reticular fibers.  Function: Supports organs, allows movement, and holds fluid.  Adipose Tissue: Page 117 of 136   Stores fat, insulates the body, and provides energy storage.  Found in subcutaneous layers, around organs, and in bone marrow.  Dense Regular Connective Tissue:  Found in tendons, ligaments, and aponeuroses.  Collagen fibers are tightly packed in one direction, providing strength in one direction.  Dense Irregular Connective Tissue:  Found in the dermis of skin and organ capsules. Page 118 of 136   Fibers are arranged irregularly, providing strength in multiple directions. 2. Cartilage:  Types:  Hyaline Cartilage: Most common, smooth and glossy; found at joints, ribs, nose, and trachea.  Fibrocartilage: Strong and rigid; found in intervertebral discs, pubic symphysis, and menisci of knees.  Elastic Cartilage: Flexible; found in the ear and epiglottis. Page 119 of 136  3. Bone (Osseous Tissue):  Compact Bone: Made up of osteons (Haversian systems), which consist of:  Lamellae: Concentric rings of mineralized bone matrix.  Lacunae: Spaces between lamellae containing osteocytes (mature bone cells).  Canaliculi: Small channels that connect osteocytes for nutrient and waste exchange.  Central Canal: Contains blood vessels and nerves.  Function: Provides structure, support, and houses bone marrow for blood cell production. Page 120 of 136  Minerals (calcium and phosphate) give bones their strength, while collagen fibers provide flexibility. 4. Blood (Vascular Tissue):  Blood is a connective tissue because it has cells suspended in a liquid matrix (plasma).  Function: Transports oxygen, nutrients, and waste products, and helps defend against infection.  Cells: Red blood cells (RBCs), white blood cells (WBCs), platelets. Clinical Relevance  Tissue Injury & Repair: Page 121 of 136   Fibroblasts play an essential role in wound healing, producing collagen fibers and ground substance for repair.  Scar Tissue: Excessive collagen production can lead to the formation of scar tissue, which may reduce the function of affected tissues.  Diseases:  Osteoarthritis: A condition where the cartilage at joints breaks down, causing pain and stiffness.  Osteoporosis: A bone disease where bone density decreases, making bones fragile and prone to fractures. Page 122 of 136 Page 123 of 136  Tissue Level of Organisation – Quiz Questions Multiple Choice Questions (MCQs) 1. Which of the following are primary functions of connective tissue? Select all that apply. A) Protection B) Blood circulation C) Storage of fat D) Synthesis of hormones E) Support and binding of organs 2. What is the characteristic feature of the matrix of connective tissue? A) It is solid in all types of connective tissue. Page 124 of 136  B) It determines the tissue's properties and may include fibers, ground substance, and fluid. C) It is only composed of collagen fibers. D) It consists solely of water with no proteins. 3. Which of the following cells in connective tissue are responsible for producing fibers and ground substance? A) Fibroblasts B) Mast cells C) Plasma cells D) Macrophages 4. Which type of connective tissue is characterized by the presence of loosely arranged fibers and is involved in the Page 125 of 136  movement of nutrients across cell membranes? A) Dense connective tissue B) Adipose tissue C) Loose (areolar) connective tissue D) Reticular connective tissue 5. What type of connective tissue is primarily involved in energy storage and thermal insulation? A) Cartilage B) Bone C) Adipose tissue D) Reticular tissue 6. Which of the following is NOT a type of cartilage? A) Hyaline cartilage Page 126 of 136  B) Fibrocartilage C) Elastic cartilage D) Collagen cartilage 7. True or False: The matrix in cartilage consists primarily of collagen fibers and ground substance like chondroitin sulfate. A) True B) False 8. True or False: Dense regular connective tissue, such as tendons and ligaments, provides structural strength and resists tensile forces in multiple directions. A) True B) False 9. What is the primary difference between dense regular and dense irregular Page 127 of 136  connective tissues? A) Dense regular tissue contains more blood vessels than dense irregular tissue. B) Dense regular tissue has fibers arranged in parallel bundles, while dense irregular tissue has fibers arranged in random directions. C) Dense irregular tissue is found only in cartilage, while dense regular tissue is found in bones. D) Dense irregular tissue is less flexible than dense regular tissue. 10. Which of the following types of connective tissue is found in the external ear and the epiglottis? A) Hyaline cartilage B) Fibrocartilage Page 128 of 136  C) Elastic cartilage D) Bone 11. Which of the following are types of connective tissue proper? Select all that apply. A) Loose (areolar) connective tissue B) Reticular connective tissue C) Fibrocartilage D) Dense (collagenous) connective tissue E) Adipose tissue 12. What is the role of mast cells in connective tissue? A) They produce collagen fibers to support tissue. B) They secrete heparin, an anticoagulant, and histamine to mediate inflammatory Page 129 of 136  responses. C) They engulf pathogens and debris. D) They store fat for energy use. Correct Answers with Rationales 1. A, C, E Rationale: The primary functions of connective tissue include protection, Page 130 of 136  energy storage (fat), and providing support and binding between organs. Blood circulation and hormone synthesis are not primary functions of connective tissue. 2. B Rationale: The matrix of connective tissue is highly variable and determines its properties. It can include fibers (like collagen or elastin), ground substance, and fluids. It is not solid in all connective tissues. 3. A Rationale: Fibroblasts are the cells that produce collagen and elastin fibers as well as ground substance. Mast cells and plasma Page 131 of 136  cells are involved in immune responses, and macrophages are involved in phagocytosis. 4. C Rationale: Loose (areolar) connective tissue has loosely arranged fibers that allow for the easy passage of nutrients and waste products. This tissue is found around organs and in mucous membranes. 5. C Rationale: Adipose tissue stores fat and provides thermal insulation. Cartilage and bone are structural tissues, while reticular tissue provides support. Page 132 of 136 6. D Rationale: There is no such thing as "collagen cartilage." Cartilage types are hyaline, fibrocartilage, and elastic cartilage. 7. A) True Rationale: The matrix of cartilage is composed of collagen fibers and a ground substance that contains chondroitin sulfate, which gives cartilage its resilience and strength. 8. B) False Rationale: Dense regular connective tissue (like tendons and ligaments) resists tensile forces in one direction, not multiple directions. Dense irregular Page 133 of 136  connective tissue resists tension in multiple directions. 9. B Rationale: The key difference between dense regular and dense irregular connective tissues is the arrangement of fibers. Dense regular tissue has fibers in parallel bundles, making it stronger in one direction, whereas dense irregular tissue has fibers in various directions, providing strength in multiple directions. 10. C Rationale: Elastic cartilage, which contains elastic fibers, is found in the external ear and epiglottis. Hyaline cartilage is found at joints and ribs, Page 134 of 136  while fibrocartilage is found in intervertebral discs. 11. A, B, D, E Rationale: The main types of connective tissue proper include loose (areolar) connective tissue, reticular connective tissue, dense (collagenous) connective tissue, and adipose tissue. Fibrocartilage is a type of cartilage, not connective tissue proper. 12. B Rationale: Mast cells release heparin and histamine, which are important in the inflammatory response. They do not produce collagen or store fat. Page 135 of 136 Page 136 of 136