Unit 3 – Cells
Cell Theory
§ The cell is the basic structural and functional unit of life
§ Cells come from ______cells
§ All living things are made of cells
Cell Membrane
§ Bilayer of lipids with imbedded proteins
§ Bilayer consists of phospholipids, ______, and glycolipids
§ Glycolipids are lipids with bound carbohydrate
§ Phospholipids have hydrophobic and hydrophilic regions
§ Membrane proteins have various functions
§ Tight junction – impermeable junction around the cell
§ ______– anchoring junction scattered along the sides of cells
§ Gap junction – a passageway that allows substances to pass between cells
Cytoplasm
§ Cytoplasm – material between plasma membrane and the nucleus
§ Cytosol – largely ______with dissolved protein, salts, sugars, and other solutes
Organelles
§ Specialized cellular compartments
§ Membranous
§ Mitochondria, peroxisomes, lysosomes, endoplasmic reticulum (ER), and Golgi apparatus
§ Nonmembranous
§ Cytoskeleton, centrioles, and ______
Mitochondria
§ Double membrane structure with shelf-like cristae
§ Makes ______via aerobic cellular respiration
§ Contains own DNA and RNA
Ribosomes
§ Granules containing protein and rRNA
§ Site of ______synthesis
§ Can be free floating or attached to the ER
Endoplasmic Reticulum
§ Interconnected tubes
§ Continuous with the nuclear membrane
§ Two varieties – ______ER with ribosomes and smooth ER without
§ RER à protein synthesis
§ SER à making lipids, storing Ca, detox of cell
Golgi Apparatus
§ Stacked, flat membranous sacs
§ ______and package proteins coming from ER
§ Proteins sent to various locations as needed
Lysosomes
§ Membranous bags containing ______enzymes
§ Digest ingested pathogens
§ Degrade old organelles
Peroxisomes
§ Membranous sacs containing oxidases and catalases
§ ______cell
Cytoskeleton
§ The “______” of the cell
§ Protein rods running through the cytosol
§ Consists of microtubules, microfilaments, and intermediate filaments
Cilia
§ Hair-like structures that move substances in one direction across cell surfaces
Flagella
§ Whip-like structures that ______cells
Nucleus
§ Gene-containing control center of the cell
§ Contains blueprints for all cellular proteins
§ Nuclear Envelope- Selectively permeable double membrane barrier containing pores
§ Chromatin- Threadlike strands of ______and histones
arranged in units called nucleosomes
Unit 4 – Histology
Histology- study of tissues; groups of cells that are similar in structure and function
Pathology– study of ______tissues in diseased organs; by normal appearance of tissues in organs, it is possible to recognize the abnormal
• Four primary tissue types are
- epithelium – ______body & organs, forms glands, lines body cavities
- connective tissue – supports, joins, protects
- nervous tissue – control, produces nerve impulses
- ______– movement, contracts
Epithelial- Epithelial tissue is the lining, covering, and glandular tissue of the body
• Epithelial tissues have no blood supply of their own (______) and depend on diffusion from the capillaries in the underlying connective tissue, both reticular and basal laminae
• If well nourished, they regenerate easily, rapidly replacing lost cells by cell division
• innervated – supplied by nerve fibers
• May be classified by cell arrangement (layers) into two general groups – ______(one-layer) and stratified (more than one cell layer) epithelium
• Simple Epithelia – single layer thick; usually very thin, concerned with absorption, not used for protection; four major types
• Stratified Epithelia – ______or more cell layers; very durable; function primarily to protect; too thick for absorption or secretion; cells divide rapidly; classified according to the shape of surface cells; four types
• Squamous, cuboidal, or columnar
· Simple Squamous
· ______layer of flattened cells with disc-shaped nuclei and sparse cytoplasm; cells rest on a basement membrane; fit together like floor tiles
· Functions
- Diffusion and filtration
- Provide a slick, friction-reducing lining in lymphatic and cardiovascular systems
-found in air sacs of lungs (O2 & CO2 diffusion)
- forms walls of capillaries (exchange of nutrients & gases)
- in the kidney (filtration of blood)
· Simple Cuboidal
· Single layer of cube-like cells with large, spherical central nuclei; rest on a basement membrane
· Function in secretion and absorption
· Common in ______and their ducts (salivary & pancreas)
· Forms the walls of the kidney tubules
· Covers the surface of the ovaries
· Simple Columnar
· Single layer of tall cells with oval nuclei; many contain cilia; rest on basement membrane
· ______cells are often found in this layer and produce lubricating and protective mucus & are often found scattered throughout this tissue
· Function in absorption and secretion
· Nonciliated type line gallbladder and digestive tract from the stomach to the anus; secrete some digestive chemicals
· Ciliated type line small bronchi, uterine tubes, and some regions of the uterus; cilia help move substances through internal passageways
· Mucosae (mucous membranes) line body cavities open to the body exterior
· Pseudostratified Columnar
· Single layer of cells with different heights; some do not reach the free surface
· Some cells are shorter than others and have nuclei appearing at different heights above the membrane giving the false (______) impression that it is stratified (more than one layer)
· Function in absorption and secretion and propulsion of mucus
· Present in the male sperm-carrying ducts (nonciliated)
· Present in the ______(ciliated) - lines the respiratory tract where mucus from goblet cells trap dust and debris, and cilia propel mucus away from lung
· Stratified Squamous
o Most ______epithelial tissue in the body
o free edge cells are squamous, basement membrane cells are cuboidal or columnar
o Thick membrane composed of several layers of cells
o Function in protection of underlying areas subjected to abrasion
o Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)
o Cellular reproduction in this tissue occurs in the deepest layer
o As newer cells grow, older ones are pushed further outward, and they tend to become flattened, accumulate a protein called keratin, and become dehydrated
o ______stratified squamous epithelium contains keratin which makes the epidermis of the skin waterproof and resistant to bacteria.
§ Considered first line of defense against bacteria
§ - Outer layers of skin are dead but kept soft by glandular secretions
o Nonkeratinized stratified squamous epithelium lines the mouth cavity, throat, vagina, and anal canal
§ also called mucosa
§ - cells on free surfaces remain alive and moist from secretions
§ can withstand abrasion but not fluid loss
· Stratified Cuboidal
o Usually consists of two cell layers; cells at free edge are cuboidal
o Fairly rare in the body, being found mainly in the ______of large glands (sweat glands, salivary glands, pancreas, mammary glands)
· Stratified Columnar
o Limited distribution in the body
o Found in the pharynx, male urethra, and lining some glandular ducts
o Also occurs at ______areas between two other types of epithelia
· Transitional
o Specialized to undergo changes in response to increased tension; stretches to permit the distension of the ______
o Several cell layers, basal cells are cuboidal, surface cells are dome shaped
o Lines the urinary bladder, ureters, and part of the urethra
o Consists of several layers of cuboidal cells when wall of organ is contracted
o When organ is distended, the tissue is stretched, and the tissue appears to contain only a few layers
o Also forms a barrier preventing spills from urinary tract
o consists of many layers when the organ wall is contracted; thinner when the wall is stretched
· Glandular
o Glands consists of one or more cells that are specialized to produce and secrete various substances into ducts or into body fluids
o Classified by:
§ Site of product release - endocrine or exocrine
§ Relative number of cells forming the gland - unicellular or multicellular
o Endocrine Glands
§ ______glands that produce hormones
§ lose their connection to the surface (ducts); secretions diffuse directly into the blood vessels or extracellular fluid
§ Secretions include amino acids, proteins, glycoproteins, and steroids
§ include thyroid, adrenals, pituitary
o Exocrine Glands
§ More numerous than endocrine glands
§ ______their products onto body surfaces (skin) or into body cavities
§ Examples include mucous, sweat, oil, pancreatic, and salivary glands
§ The only important unicellular gland is the goblet cell which secrete mucus; found in linings of respiratory, digestive, urinary, and reproductive systems
§ Multicellular exocrine glands are composed of a duct and secretory unit
§ Classified according to:
· Simple or compound duct type
· Structure of their secretory units
· Glandular secretion are classified according to whether they consist of cellular products or portions of the glandular cells
o Merocrine glands – products are secreted by exocytosis (e.g., pancreas, sweat, and salivary glands)
o Apocrine glands – portion of secretory cell and secretion are discharged; mammary glands
o ______glands entire secretory cell with enclosed secretion discharged (e.g., sebaceous glands)
Connective Tissue
o Found throughout the body; most abundant and widely distributed in primary tissues
§ Connective tissue proper
§ Cartilage
§ ______
§ Blood
o Functions include:
§ Binding and support
§ Protection
§ Insulation
§ Transportation
· Characteristics of Connective Tissue
o Connective tissues have:
§ Mesenchyme as their common tissue of origin
§ Varying degrees of ______
§ Nonliving extracellular matrix, consisting of ground substance and fibers
· Structural Elements of Connective Tissue
o Ground substance – unstructured material that fills the space between cells
o Fibers – collagen, elastic, or reticular
o Cells – fibroblasts, chondroblasts, osteoblasts, and hematopoietic stem cells
· Ground Substance
o Interstitial (tissue) fluid
o Adhesion proteins – fibronectin and laminin
o ______– glycosaminoglycans (GAGs)
o Functions as a molecular sieve through which nutrients diffuse between blood capillaries and cells
· Fibers
o Collagen – tough; provides high tensile strength
o Elastic – long, thin fibers that allow for stretch
o Reticular – branched collagenous fibers that form delicate networks
· Cells
o Fibroblasts – connective tissue proper
· Chondroblasts – cartilage
· ______– bone
· Hematopoietic stem cells – blood
· White blood cells, plasma cells, macrophages, and mast cells
· Connective Tissue: Embryonic
o Mesenchyme – embryonic connective tissue
o Gel-like ground substance with fibers and star-shaped mesenchymal cells
o Gives rise to all other connective tissues
o Found in the ______
· Six basic types of connective tissue proper- classified by ground substance and type of fibers
o 1) Areolar connective tissue
§ Gel-like matrix with all three connective tissue fibers
§ Fibroblasts, macrophages, mast cells, and some white blood cells
§ Wraps, binds, and cushions organs
§ Widely distributed throughout the body
§ Very ______
o 2) Adipose connective tissue
§ Commonly called ______; store fat within cytoplasm; nuclei pushed to one side of cell
§ Matrix similar to areolar connective tissue with closely packed adipocytes
§ Reserves food stores, insulates against heat loss, cushions eyeballs in their sockets, supports and protects
§ Found under skin, around kidneys, within abdomen, and in “fat depots” (breasts & hips)
§ Local fat deposits serve nutrient needs of highly active organs
§ Formed prenatally and during first year of life; cells swell in size but do not increase in number after 1 year of age
o 3) Reticular connective tissue
§ Delicate network of interwoven reticular fibers in a jellylike matrix
§ Reticular cells lie in a fiber network
§ Some phagocytic cells
§ Forms a soft internal skeleton, or stroma, that supports other cell types
§ Found in lymph nodes, bone marrow, and the spleen
o 4) Dense regular connective tissue
§ Large amounts of closely packed collagen fibers with a few elastic fibers that run parallel to direction of force
§ Major cell type is fibroblasts
§ Strong, flexible support
§ Found in ______(muscle to bone), ligaments (bone to bone across joints), and aponeuroses
o 5) Dense irregular connective tissue
§ Irregularly arranged ______fibers with some elastic fibers
§ Major cell type is fibroblasts
§ Withstands tension in many directions providing structural strength
§ Found in the dermis of skin, submucosa of the digestive tract, and fibrous organ and joint capsules
o 6) Elastic connective tissue
§ Elastic fibers that are irregularly arranged
§ Found in walls of arteries, trachea, bronchial tubes, between vertebrae
§ Function: capable of strength with ______and recoil in several directions
· Cartilage – less hard and more flexible than bone
o Found in only a few places in the body
o Consist of chondrocytes (cells) occupying tiny spaces called lacunae within an elastic matrix; semisolid
o Functions in support and protection
o Few blood vessels; heals ______
o Three types exist which are distinguished by the type and amount of fibers embedded within the matrix
· Connective Tissue: Hyaline Cartilage (gristle)
o Has many collagen fibers hidden by a rubbery matrix with a glassy blue-white appearance
o Chondrocytes lie in lacunae
o Supports, reinforces, cushions, and resists compression
o Forms the costal cartilage
o Found in embryonic skeleton, the ______of long bones, nose, trachea, and larynx
· Connective Tissue: Elastic Cartilage
o Contains many compressed, elastic fibers; very strong & flexible
o Similar to hyaline cartilage but with more elastic fibers
o Maintains shape and structure while allowing flexibility
o Supports external ______(pinna), larynx, and the epiglottis
· Connective Tissue: Fibrocartilage Cartilage
o Matrix similar to hyaline cartilage but less firm with highly compressed, thick collagen fibers
o Provides tensile strength and absorbs compression shock
o Found in intervertebral discs, the pubic symphysis, and in discs of the knee joint
· Connective Tissue: Bone (Osseous Tissue)
o most rigid of all connective tissues