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Questions and Answers
What is the primary energy currency produced by mitochondria?
What is the primary energy currency produced by mitochondria?
Which function is NOT associated with mitochondria?
Which function is NOT associated with mitochondria?
What structure increases the surface area of the inner mitochondrial membrane?
What structure increases the surface area of the inner mitochondrial membrane?
Which cellular process is aided by mitochondria during fertilization?
Which cellular process is aided by mitochondria during fertilization?
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What do ribosomes primarily function as?
What do ribosomes primarily function as?
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Which type of organelles are characterized as not bound by a membrane?
Which type of organelles are characterized as not bound by a membrane?
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What is found in the mitochondrial matrix that assists in ATP synthesis?
What is found in the mitochondrial matrix that assists in ATP synthesis?
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What is the main characteristic of mitochondria compared to other organelles?
What is the main characteristic of mitochondria compared to other organelles?
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What type of fibers are characterized by their ability to stretch and recoil?
What type of fibers are characterized by their ability to stretch and recoil?
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Which type of connective tissue is classified as supportive tissue?
Which type of connective tissue is classified as supportive tissue?
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What is the primary characteristic of loose connective tissue?
What is the primary characteristic of loose connective tissue?
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Reticular fibers serve what primary function in the body?
Reticular fibers serve what primary function in the body?
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Which type of connective tissue is primarily composed of fat cells?
Which type of connective tissue is primarily composed of fat cells?
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Which type of connective tissue is known for its abundance of fibers with fewer cells?
Which type of connective tissue is known for its abundance of fibers with fewer cells?
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What main function does loose (areolar) connective tissue serve in the body?
What main function does loose (areolar) connective tissue serve in the body?
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Which connective tissue type is characterized as liquid connective tissue?
Which connective tissue type is characterized as liquid connective tissue?
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What is the primary function of the lymphatic vessels?
What is the primary function of the lymphatic vessels?
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Which of the following organs is primarily responsible for the maturation of T-lymphocytes?
Which of the following organs is primarily responsible for the maturation of T-lymphocytes?
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Which type of lymphatic vessel is responsible for transporting absorbed lipids and lipid-soluble vitamins to the blood?
Which type of lymphatic vessel is responsible for transporting absorbed lipids and lipid-soluble vitamins to the blood?
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How does lymph move through the lymphatic vessels?
How does lymph move through the lymphatic vessels?
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What condition must interstitial fluid achieve to be classified as lymph?
What condition must interstitial fluid achieve to be classified as lymph?
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Which type of lymphocyte is primarily involved in the immune response against specific microbes and abnormal cells?
Which type of lymphocyte is primarily involved in the immune response against specific microbes and abnormal cells?
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Which of the following locations is classified as a secondary site for lymphocyte function?
Which of the following locations is classified as a secondary site for lymphocyte function?
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Which vitamins are transported by the lymphatic system after absorption in the gastrointestinal tract?
Which vitamins are transported by the lymphatic system after absorption in the gastrointestinal tract?
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What do the tiny rods in the M line do?
What do the tiny rods in the M line do?
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Which proteins are classified as contractile proteins?
Which proteins are classified as contractile proteins?
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What initiates the muscle action potential in a muscle cell?
What initiates the muscle action potential in a muscle cell?
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What role does acetylcholinesterase play in muscle contraction?
What role does acetylcholinesterase play in muscle contraction?
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Which structural protein provides elasticity and extensibility in muscles?
Which structural protein provides elasticity and extensibility in muscles?
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Which part of the muscle fiber is the neuromuscular junction responsible for?
Which part of the muscle fiber is the neuromuscular junction responsible for?
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What occurs after the arrival of a nerve impulse at the nerve terminal?
What occurs after the arrival of a nerve impulse at the nerve terminal?
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The contraction cycle involves which of the following processes?
The contraction cycle involves which of the following processes?
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What process is responsible for the formation of bone tissue from cartilage?
What process is responsible for the formation of bone tissue from cartilage?
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Which cell type is primarily responsible for bone resorption?
Which cell type is primarily responsible for bone resorption?
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What is the primary function of the rib cage?
What is the primary function of the rib cage?
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Which of the following constitutes the majority of the bone matrix?
Which of the following constitutes the majority of the bone matrix?
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What type of bone is characterized by its irregular structure and is typically found at the ends of long bones?
What type of bone is characterized by its irregular structure and is typically found at the ends of long bones?
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What cell type is responsible for creating new bone tissue?
What cell type is responsible for creating new bone tissue?
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Which anatomical type of bone is typically longer than it is wide?
Which anatomical type of bone is typically longer than it is wide?
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What role do osteocytes play in bone tissue?
What role do osteocytes play in bone tissue?
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What is the primary role of neurilemma in nerve processes?
What is the primary role of neurilemma in nerve processes?
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Which type of neuron carries action potentials towards the CNS?
Which type of neuron carries action potentials towards the CNS?
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What structure is primarily responsible for forming myelin sheaths in the CNS?
What structure is primarily responsible for forming myelin sheaths in the CNS?
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Which type of cell is responsible for maintaining the blood-brain barrier?
Which type of cell is responsible for maintaining the blood-brain barrier?
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What is the primary function of microglia in the CNS?
What is the primary function of microglia in the CNS?
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Which type of skin is typically found in the palms and soles of the body?
Which type of skin is typically found in the palms and soles of the body?
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What type of epithelium makes up the epidermis?
What type of epithelium makes up the epidermis?
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What is the primary role of keratinocytes in the epidermis?
What is the primary role of keratinocytes in the epidermis?
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What is true about Langerhans cells?
What is true about Langerhans cells?
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Which layer of the epidermis contains dead cells?
Which layer of the epidermis contains dead cells?
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Study Notes
Histology - Basic for PT1 2024-25
- Histology is the science that deals with the microscopic structure of cells and tissues.
- The cell is the basic unit of life and the structural and functional unit of all living tissues.
- The cell is the basic unit of life.
- The science of histology is concerned with the microscopic structure of cells and tissues.
- This course is a basic introduction to cell biology, using objectives to guide the learning process.
Learning Objectives (Lecture 1)
- Distinguish between prokaryotic and eukaryotic cells.
- Identify the structure of a living cell's plasma membrane, cytoplasm, and nucleus, and their functions.
- Understand the structure and function of membranous organelles (endoplasmic reticulum, Golgi apparatus, lysosomes, and mitochondria).
Types of Microscopes
- Light Microscope (LM)
- Transmission Electron Microscope (TEM)
Cell Diversity
- Cells in the same organism show enormous diversity in size, shape, and internal organization.
- Examples of this diversity are seen in the vast differences between a nerve cell and a red blood cell in the human body.
Cell Size
- The female egg is the largest cell in the human body.
- Most other cells are only visible under a microscope.
Cell Shape
- Cell shape reflects a diversity of function.
- The shape of a cell depends on its function.
Internal Cell Organization
- Prokaryotic cells lack a nucleus and membrane-bound organelles.
- Eukaryotic cells have a nucleus and membrane-bound organelles.
Types of Cells
- Prokaryotes
- Eukaryotes (Plant and Animal Cells)
Prokaryotic Examples
- Only Bacteria
- Capsule
- Cell Wall
- Cytoplasmic Membrane
- Ribosomes
- Pili
- Cytoplasm
- Nucleoid
- Flagella
Eukaryotic Cells
- Plant Cells and Animal Cells
Anatomy of an Animal Cell
- Mitochondria
- Microfilaments
- Lysosome
- Rough Endoplasmic Reticulum
- Peroxisome
- Centrioles
- Micro Tubules
- Golgi Apparatus
- Cilia
- Smooth Endoplasmic Reticulum
- Nucleus
- Nuclear pores
- Plasma Membrane
- Nucleolus
- Nuclear Envelope
- Chromatin
- Rough Endoplasmic Reticulum
Anatomy of a Plant Cell
- Vacuole
- Chloroplast
- Cell Membrane
- Cell Wall
- Golgi apparatus
- Mitochondrion
Cytosol and Cytoplasm
- The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs.
- The cytoplasm is a collective term for the cytosol plus the organelles suspended within the cytosol.
Organelles
- Both membranous and non-membranous organelles
-
Membranous Organelles
- Cell membrane (plasma membrane)
- Mitochondria
- Endoplasmic reticulum (rough and smooth)
- Golgi apparatus
- Lysosomes
-
Non-membranous Organelles
- Ribosomes
- Cytoskeleton
Plasma Membrane (Cell Membrane)
- The boundary of the cell, composed of three distinct layers.
- Two layers of fat and one layer of protein.
- Difficult to see with H&E stains.
- Visible with silver (Ag) stain.
- Appears as 2 electron-dense lines separated by an electron-lucent one (trilamellar) in electron micrographs.
Molecular Structure of Cell Membrane
-
1-Lipid Component
-
Phospholipid molecules comprise the lipid bilayer, each having a head and two tails.
-
Hydrophilic heads face outward.
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Hydrophobic tails face inwards.
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Cholesterol molecules stabilize the membrane and modulate fluidity.
-
2- Protein Component
-
Extrinsic (peripheral) proteins are loosely attached to the membrane surface.
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Intrinsic (integral) proteins extend across the bilayer and act as pathways for ions and molecules.
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Channel proteins & carrier proteins
-
3- Carbohydrate Component
-
Glycoproteins and glycolipids form the cell coat (glycocalyx)
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Functions as cell adhesion and immune defense.
Functions of Cell Membrane (Bulk Transport)
-
Endocytosis
-Phagocytosis (engulfing solid particles) and
-Pinocytosis (engulfing fluid droplets)
- Receptor-mediated endocytosis (selective transport of specific molecules)
- Exocytosis (moving substances from inside the cell to the outside)
The Nucleus
- Brain of the cell.
- Border by a porous membrane (nuclear envelope).
- Contains thin fibers if DNA & protein called chromatin.
- Contains a small round nucleolus, which produces ribosome RNA to make ribosomes
- Rod-shaped chromosomes
Endoplasmic Reticulum
- Complex network of transport channels.
- Smooth ER (no ribosomes): functions in lipid and steroid hormone synthesis.
- Rough ER (with ribosomes): functions in protein synthesis and packaging.
Golgi Apparatus
- Modifies, packages, stores and transports proteins to be secreted (hormones, enzymes, antibodies).
- Works with the endoplasmic reticulum and ribosomes to synthesize proteins.
Lysosomes
- Recycling Center
- Contain a variety of enzymes to recycle cellular debris, digest food particles, nutrients, foreign and dead materials
- Three types :
- Phagolysosome: digests material phagocytosed by the cell
- Multivesicular body: formed from the fusion between a primary lysosome with vesicles from endocytosis
- Autolysosome: contains old organelles
Mitochondria
- Double membranous organelle.
- Size of a bacterium.
- Contains its own DNA (mDNA)
- Responsible for respiration and energy production (ATP).
Function of Epithelial Tissue
- Protective barrier
- Absorption
- Filtration
- Secretion
Classification of Epithelium
- Based on thickness ("simple" and "stratified")
- Shape ("squamous," "cuboidal," and "columnar")
Features of Epithelium (Surface)
- Microvilli, cilia, and flagella.
Features of the Basal Surface of Epithelium
- Basal lamina
- Basement membrane
Features of Lateral Surface of Epithelium
- Cell junctions (tight junctions, gap junctions, desmosomes).
Types of Connective Tissue
- Loose Connective Tissue (Areolar, Adipose, Reticular, Mucoid)
- Dense Connective Tissue (Regular, Irregular, Elastic)
- Supportive Connective Tissue (Cartilage: Hyaline, Fibrocartilage, Elastic) (Bone)
- Fluid Connective Tissue (Blood)
Cell Types (Connective Tissue)
- Resident
- Fibroblasts
- Adipose cells
- Pericytes
- Mast cells
- Macrophages
- Transient
- Plasma cells
- Lymphocytes
- Neutrophils
- Eosinophils
- Basophils
- Monocytes
- Macrophages
Matrix Cells (Connective Tissue)
- Fibroblasts: make connective tissue/fibers.
- Chondroblasts: produce cartilage
- Osteoblasts: produce bone
- Hematopoietic stem cells: produce blood.
Matrix Fibers (Connective Tissue)
- Collagen fibers: most abundant; provide flexibility and tensile strength.
- Elastic fibers: intermediate; allow for stretch and recoil.
- Reticular fibers: small and delicate; form a structural framework for some organs.
Types of Muscle Tissue
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
Skeletal Muscle Anatomy
- Epimysium
- Perimysium
- Endomysium
Microscopic and Functional Anatomy of Skeletal Muscle
- Fibers are long and cylindrical.
- Each fiber is formed by fusion of embryonic cells, hence multinucleate.
- Nuclei are peripherally located.
- Myofibrils are made up of myofilaments.
- Myofibrils are long rods with cytoplasm.
- Composed of functional units called sarcomeres.
Sarcomere
- Z discs anchor the myofilaments.
- Thin filaments are composed of actin.
- Thick filaments are composed of myosin.
- A band contains the full length of the thick myosin filament
- I Band contains the thin actin filaments
- H zone is the middle of the A band that contains thick myosin filaments.
- M line holds thick filaments together.
Myofibrils: Proteins of Muscle
- Contractile proteins (myosin, actin)
- Regulatory proteins
- Structural protein
Innervation of Skeletal Muscle
- Each skeletal muscle is supplied by one nerve, artery, and two veins.
- A motor neuron supplies multiple muscle cells at the neuromuscular junction.
Events Occurring After Nerve Signal
- Arrival of nerve impulse at nerve terminal causes the release of ACh.
- ACh binds to receptors on muscle motor end plate opening channels.
- Inside of muscle cell becomes more positive, triggering a muscle action potential.
- Release of Ca+2 from the SR into the sarcoplasm triggers the sliding of actin filaments over myosin.
- Acetylcholinesterase breaks down the ACh so the muscle cells relax.
Relaxation
- Acetylcholinesterase breaks down ACh within the synaptic cleft.
- Muscle action potential ceases
- Ca+2 release channels close
- Active transport pumps Ca+2 back into storage in the sarcoplasmic reticulum.
- Calcium-binding protein (calsequestrin)
T-tubules & Sarcoplasmic Reticulum (SR)
- Special tubular system.
Tendons & Ligaments
- Connective tissues.
- Tendons connect muscle to bone.
- Ligaments connect bone to bone
The Vascular System
- Major components: Arteries,Veins, &Capillaries
- Three Layers of vessel: Intima, Media, &Adventitia
- Function of blood vessels.
- Differences between a medium-sized artery & medium-sized vein
Capillaries
- Formed by a single layer of simple squamous epithelium resting a basal lamina, which curls up into a tube
- Three types (continuous, fenestrated, sinusoid).
Lymphatic System
- Network of vessels throughout body that transport lymph back into the blood.
- Lymph is a fluid similar to plasma
- Pathways
- Lymphatic capillaries
- Lymphatic vessels
- Lymph nodes
- Lymphatic trunks
- Collecting ducts
- Lymphatic vessels
- Lymphatic trunks
- Lymphatic ducts (thoracic and right)
Lymphatic Organs
- Primary (bone marrow & thymus).
- Secondary (lymph nodes, spleen, tonsils, and Peyer's patches)
Functions of Lymphatic System
- Drains interstitial fluid and returns it to blood circulation.
- Transports dietary lipids.
- Carries out immune responses
Tissue Fluid & Lymph
- Lymph moves due to skeletal muscles contraction, pressure change in the thoracic cavity.
- Interstitial fluid – High in nutrients, oxygen, and small protein.
The Thymus
- Asymmetric bilobed organ where mature T-cells are formed.
- Located in the superior mediastinum, behind the manubrium
Red Bone Marrow
- Site of blood cell formation.
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Description
Test your knowledge on key concepts related to mitochondria, connective tissues, and cellular processes. This quiz covers fundamental questions about cellular structures, their functions, and characteristics. Perfect for students studying cell biology and histology.