ANP Cells & Tissue PDF

Section 3.1: Cells are the smallest unit of life Modern Cell Theory o Cell is the smallest unit of life o All cells come from preexisting cells o All organisms are made of 1+ cell Cell Shape = Cell function but all cells have the same basic parts 250 tri...

Section 3.1: Cells are the smallest unit of life Modern Cell Theory o Cell is the smallest unit of life o All cells come from preexisting cells o All organisms are made of 1+ cell Cell Shape = Cell function but all cells have the same basic parts 250 trillion type of cells that are 2 micrometers Human cells have 3 basic parts o Plasma membrane o Cytoplasm o Nucleus Extra cellular materials are substances that contribute to body mass outside of cell o ECF (Interstitial fluid, blood plasma, cerebrospinal fluid which has sugars, amino acids, sugars, fatty acids, regulatory substances and wastes) o Cellular secretions (Substances that aid in digestion and lubricants) o Extracellular Matrix (Jellylike substance composed of proteins and polysaccharides, serves as cell glue that binds cells together, abundant in connective tissue Section 3.7: Cell adhesion molecules and membrane receptors allow the cell to interact with its environment Cell Adhesion Molecules (CAMs), thousands of them are found in the body and they help embryonic development, wound repair and immunity. Sticky glycoproteins (cadherins and integrins) act as: o Molecular Velcro that cells use to anchor themselves in the extracellular space o Arms that migrate cells use to haul themselves past each other o SOS signals sticking out from the blood vessel lining that gather white blood cells to injury or infection o Sensor that transmits information about changes in the extracellular matrix into the cell like migration, growth and specialization Plasma membrane receptors = Integral proteins that serve as binding sites known and membrane receptors  o Contact Signaling – Cells come together and touch (recognize). Used for immunity o Chemical Signaling – Signals originate outside the cell. A ligand (chemical messenger) binds to a specific receptor and initiates a response. (Neurotransmitters, hormones and paracrine) G Protein-coupled receptors exert effects indirectly through a G protein (molecule that acts as an enzyme or ion channel) which generates one or more intracellular chemical signals known as second messages. Two important second messengers are cyclic AMP and Ca which are active protein kinase enzymes. These enzymes transfer phosphate groups from ATP to other proteins activating more enzymes. One enzyme catalyzes many (G protein). Cytoplasm – The cellular material between the plasma and the nucleus. Composed of cytosol, inclusions and organelles o Cytosol – semitransparent fluid which the cytoplasmic elements are suspended. It has colloid and a true solution. It’s largely water, proteins, salts, sugars and a variety of other solutes o Inclusions - chemical substances that may or may not be present, depending on the cell type. An example is glycogen granules in the liver and muscle cells; lipids in fat cells and melanin in hair and skin o Organelles – Metabolic machinery of the cell. They all carry out specific functions Section 3.8: Cytoplasmic organelles each perform a specialized task Mitochondria – Provide most ATP, closed by the outer membrane but the inner membrane folds inwards making cristae that protrude into the matrix. Fission is a process where the mitochondria forms more cristae to make more ATP Ribosome – Composed of proteins and varities of RNA, it consists of a large and small subunit and is the site of protein sythesis. There are free ribosomes that float in cytosol and membrane bound ones attatched to RER. Endoplasmic Reticulum – Tubes and sacs that make cisterns o Rough ER – Coated with ribosomes, where proteins assemble and when theyre complete they go to the Golgi apparatus. Integral proteins  and phospholipids are made at the rough er and sugars are attatched, lipid enzymes also have their active sites on the er. o Smooth ER – It plays no role in protein synthesis but it does metabolize lipids, synthesize cholesterol, steroids, hormones, detox drugs, breaks down glycogen and stores calcium ions Golgi Apparatus – It is a traffic director for cellular proteins. It modifies, concentrates and packages lipids and proteins made at the rough ER into vesicles Lysosomes – Spherical organelles that contain digestive enzymes. They have phagocytes (cells that dispose of cellular debris and bacteria). They kill all kinds of biological molecules and work best in acidic conditions o The lysosomal membrane – Contains H+ protein pumps to maintain Lysosomes pH. It also retains dangerous lysosomal enzymes and permits products of digestion from escaping (digestion safely occurs) o Lysosomes digest particles taken in by endocytosis (bacteria, viruses and toxins), it gets rid of worn out or non functional organelles, performs metabolic functions, breaks down bone to release calcium. Lysosome rupture = autolysis Peroxisome – Spherical membranous sacs containing enzymes (oxidases and catalases). Oxidases use O2 to detox harmful substances like alcohol. They neutralize free radicals which are highly reactive chemicals. They also convert hydrogen peroxide which the catalase converts to water (hydrogen peroxide and free radicals are products of cell metabolism). Peroxisomes also detox and metabolize and are made at the ER Endomembrane – System of organelles that work together to produce, get rid of, store and export biological molecules. (ER, Golgi, vesicles, lysosome) Cytoskeleton – Cell skeleton that supports the cell and generates movement. o Microfilaments – Made of actin filaments which break down and reform smaller subunits changing the cell’s shape. They are attatched to cell adhesion molecules, responsible for amoeboid movement and membrane changes in endo/exocytosis, they also help muscles contract o Intermediate filaments – Twists of tetramer fibrils. They are stable and permanent and attach to desmosomes acting as cables to resist pulling forces exerted on the cell.  o Microtubules – Hollow tubes made of tubulin. They determine the overall shape of the cell and distribution of cellular organelles by assembling and disassembling at the same or different sites. Organelles attach to them and motor proteins move them to reposition them (powered by ATP) ▪ Centrosomes – microtubule organizing center and makes a matrix called centrioles. The centrosome generates microtubules and organizes mitotic spindle in cell division. Each centriole contains nine triplets of microtubules. Centrioles form bases of cilia and flagella Section 3.12: Messenger RNA carries instructions from DNA for building proteins DNA's Role: DNA is the blueprint for protein synthesis but does not dictate the structure of lipids or carbohydrates. Proteins and Cells: Cells act as protein factories, creating a wide range of proteins that determine their structure and function. Genes and DNA: A gene is a segment of DNA that carries instructions for making one polypeptide (protein). DNA bases (A, T, G, C) form triplets, with each triplet coding for a specific amino acid. Exons and Introns: Exons in genes code for proteins, while introns are non-coding sequences. Introns can play roles in regulating gene expression and evolution. RNA and Protein Synthesis: RNA helps DNA's instructions get translated into proteins because DNA stays in the nucleus while protein synthesis happens in the cytoplasm. Types of RNA: mRNA: Carries the DNA message to the cytoplasm for protein synthesis. rRNA: Forms ribosomes, the site where proteins are made.  tRNA: Delivers amino acids to the ribosome for protein assembly. Transcription: DNA’s information is copied to mRNA in the nucleus. Translation: mRNA's instructions are decoded in the cytoplasm to build polypeptides (proteins). RNA Processing: Before mRNA leaves the nucleus, introns are removed, and exons are spliced together to create functional mRNA. Translation: Converts mRNA's nucleotide sequence into an amino acid sequence to form proteins. Genetic Code: The set of rules that translates DNA/RNA codons into amino acids. Codons: Triplets of bases in mRNA that correspond to specific amino acids (e.g., AUG for methionine/start codon). Stop Codons: UAA, UAG, UGA signal the end of protein synthesis. Redundancy: Multiple codons can code for the same amino acid, reducing errors during protein synthesis. tRNA Role: tRNA carries amino acids and matches anticodons to mRNA codons. Ribosome: Facilitates the interaction between tRNA and mRNA during translation. Translation Phases: Initiation, elongation (codon recognition, peptide bond formation, translocation), and termination. Polyribosomes: Multiple ribosomes can translate the same mRNA simultaneously for efficiency. ER Signal Sequence: Directs ribosome-mRNA complexes to the rough ER for protein processing. Genetic Information Transfer: Information moves from DNA to RNA to protein, determined by complementary base pairing.  DNA to mRNA: DNA base sequences (triplets) are transcribed into complementary mRNA codons (uracil replaces thymine). tRNA Role: tRNA anticodons match mRNA codons, restoring the original DNA triplet sequence (except T is replaced by U). Translation Process: Begins with methionine (AUG codon) and ends with a stop codon (UGA), forming the amino acid sequence of the polypeptide. Other RNA Roles: o miRNAs: Small RNAs that regulate gene expression by silencing mRNA or promoting its degradation. o siRNAs: Externally derived RNAs that interfere with viral replication by blocking protein translation. Section 4.2: Epithelial tissue covers body surfaces, lines cavities, and forms glands Epithelial tissue is a sheet of cells that covers a body surface or cavity o Covering/Lining - Forms the outer layer of skin, open cavities of urogenital, digestive, respiratory system and covers walls/organs of closed ventral body cavity o Glandular Epithelium – Forms glands of the body Epithelia forms boundaries and serves many functions like o Protection o Absorption o Filtration o Excretion o Secretion o Sensory reception  Polarity of Epithelial Tissue: Epithelial cells have distinct structural and functional differences between the apical and basal surfaces. Apical Surface: Exposed to the body's exterior or internal cavities. May contain microvilli (increase surface area for absorption/secretion) or cilia (help move substances). Basal Surface: Attached to underlying connective tissue. Supported by the basal lamina, which serves as a selective filter and scaffold during wound repair. Specialized Contacts: Cells are tightly packed with tight junctions (prevent material leakage) and desmosomes (provide mechanical stability). Support and Regeneration: Supported by connective tissue. High capacity for regeneration when adequately nourished. Avascular but Innervated: Lacks blood vessels but is supplied with nerve fibers. Functions: Protection, absorption, secretion, and sensation. Simple Epithelium Types: Simple Squamous Epithelium: Thin, permeable, allowing diffusion and filtration (e.g., lungs, kidneys). Simple Cuboidal Epithelium: Secretion and absorption (e.g., kidney tubules). Simple Columnar Epithelium: Absorption and secretion; can have microvilli or cilia (e.g., digestive tract). Pseudostratified Columnar Epithelium:  Appears stratified but all cells touch the basement membrane. Functions in secretion and ciliary movement (e.g., respiratory tract). Stratified Epithelium Types: Stratified Squamous Epithelium: Provides protection in high- abrasion areas (e.g., skin, mouth); can be keratinized or non- keratinized. Stratified Cuboidal/Columnar Epithelium: Rare, found in ducts of glands. Transitional Epithelium: Found in the urinary bladder, allows stretching as it transitions between shapes (cuboidal to squamous). Gland Definition: Consists of one or more cells that make and secrete a product (secretion), which is an aqueous fluid typically containing proteins, lipids, or steroids. Secretion Process: Active process where cells obtain substances from blood, chemically transform them, and discharge the product. Classification of Glands: Endocrine ("internally secreting"): Ductless glands that release hormones into interstitial fluid, which enter the bloodstream. Exocrine ("externally secreting"): Secrete products onto body surfaces or into cavities via ducts (e.g., sweat, salivary glands). Unicellular glands: Exocrine glands, like goblet cells, which secrete mucin forming mucus. Multicellular glands: More complex, with ducts and secretory units (e.g., tubular, alveolar, or tubuloalveolar). Endocrine Glands: Lose their ducts during development. Hormones are secreted directly into extracellular space, enter blood, and affect target organs.  Exocrine Glands: Secrete onto body surfaces or into body cavities. Unicellular example: Goblet cells, which secrete mucin. Multicellular glands: Have ducts and secretory units; classified by structure (simple or compound) and secretory unit shape (tubular or alveolar). Modes of Secretion: Merocrine glands: Secrete products by exocytosis without altering the cell. Holocrine glands: Cells accumulate products and rupture, releasing products with cell fragments. Apocrine glands: Controversial in humans; cells accumulate products, pinch off part of the cell, and then repair themselves. Section 4.3: Connective tissue is the most abundant and widely distributed tissue in the body Major Functions of Connective Tissue: Binding and supporting Protecting Insulating Storing reserve fuel Transporting substances within the body (e.g., blood) Four Main Classes of Connective Tissue: 1. Connective Tissue Proper o Loose Connective Tissue: Areolar, adipose, reticular o Dense Connective Tissue: Regular, irregular, elastic  o Cells: Fibroblasts, fibrocytes, defense cells, adipocytes o Matrix: Gel-like ground substance with collagen, reticular, and elastic fibers o Functions: Binding, resisting tension, storing fat, water, and salts 2. Cartilage o Subtypes: Hyaline, elastic, fibrocartilage o Cells: Chondroblasts and chondrocytes o Matrix: Gel-like ground substance with collagen and elastic fibers o Functions: Cushioning and supporting structures, resisting compression 3. Bone Tissue o Subtypes: Compact, spongy o Cells: Osteoblasts and osteocytes o Matrix: Gel-like ground substance calcified with inorganic salts, collagen fibers o Functions: Resisting compression and tension, providing support 4. Blood o Cells: Red blood cells, white blood cells, platelets o Matrix: Plasma (fluid), no fibers o Functions: Transporting nutrients, gases, wastes, and hormones Common Characteristics of Connective Tissue: 5. Extracellular Matrix: Composed of ground substance and fibers, providing support and flexibility.  6. Common Origin: All connective tissues derive from mesenchyme (embryonic tissue). Structural Components of Connective Tissue: Ground Substance: Unstructured material with interstitial fluid, cell adhesion proteins, and proteoglycans. It allows diffusion of nutrients and supports cells. Fibers: o Collagen fibers: Strong, high tensile strength. o Elastic fibers: Provide flexibility and stretch. o Reticular fibers: Form delicate networks supporting soft tissue. Cells: o Blast cells (immature) form the matrix. o Cyte cells (mature) maintain the matrix. o Other cell types: Adipocytes (store fat), leukocytes (immune response), mast cells (inflammatory response), and macrophages (immune cells). Vascularity: Cartilage: Avascular (no blood supply) Dense connective tissue: Poorly vascularized Other types: Richly vascularized Connective tissue is classified into four main categories: 7. Blood o No subcategories. 8. Bone o No subcategories. 9. Cartilage o Subcategories: ▪ Hyaline Cartilage: The most abundant, provides support and flexibility, found in the nose, trachea, and at the ends of long bones. ▪ Elastic Cartilage: Contains more elastic fibers, providing flexibility and support, found in the external ear and epiglottis. ▪ Fibrocartilage: A mix of hyaline cartilage and dense connective tissue, offering strong support under high pressure, such as in intervertebral discs. 10. Connective Tissue Proper o Subcategories: ▪ Loose Connective Tissue: Areolar: The most widely distributed, serving as packing between tissues, holding body fluids, and providing nutrients to surrounding cells. Adipose (Fat) Tissue: Primarily for nutrient storage and insulation, located under the skin, around kidneys, and in the abdomen. Reticular: Forms a supportive stroma for blood cells, found in lymph nodes, spleen, and bone marrow. ▪ Dense Connective Tissue:  Dense Regular: Collagen fibers aligned in parallel, forming tendons and ligaments for resistance to tension. Dense Irregular: Collagen fibers arranged in various directions, providing structural strength to the dermis and fibrous capsules of organs. Elastic: Contains a high proportion of elastic fibers, allowing for stretching, found in large arteries and certain vertebral ligaments. Bone (Osseous Tissue) Characteristics: o Hard and rigid due to the presence of inorganic calcium salts in addition to collagen fibers. o Contains a matrix that is similar to cartilage but more mineralized. o Osteoblasts produce the organic portion of the matrix, and calcium salts are deposited on and between the fibers. o Mature bone cells, called osteocytes, are located in lacunae within the matrix. Structure: o Osteons: Structural units of bone, resembling tree rings. o Lamellae: Concentric rings of bony matrix surrounding central canals. o Central Canals: Contain blood vessels and nerves. Functions:  Supports and protects body structures. o Provides levers for muscle action. o Stores calcium, other minerals, and fat. o Bone marrow inside bones is a site for blood cell o formation (hematopoiesis). Location: o Found in all bones of the body. Blood Characteristics: o A fluid connective tissue with a nonliving matrix called plasma. o Blood cells are suspended in plasma. Components: o Red Blood Cells (Erythrocytes): The most abundant, involved in oxygen transport. o White Blood Cells (Leukocytes): Scattered, involved in immune response. o Platelets: Involved in blood clotting. Function: o Transports respiratory gases, nutrients, wastes, and other substances throughout the body. Location: o Confined within blood vessels. Both bone and blood are vital to maintaining bodily functions, with bone providing structural support and protection, and blood serving as the main transport system within the body. 4o mini