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  protein synthesis
 SER  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
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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
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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
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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
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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 __________
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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
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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
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Functions in support and protection
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Few blood vessels; heals _____________
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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)
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o most rigid of all connective tissues
o Supports, protects, and provides levers for muscular action
o Stores ______________, minerals, and fat
o Calcium phosphate responsible for hardness
o Collagenous fibers gives flexibility
o ___________________ are found in lacunae and are well vascularized
o vascularized Periosteum – outer surface of bone; site for attachment of ligaments and tendons
o Compact bone – hard outer portion
o Spongy bone – porous, vascular inner portion; site for bone marrow (blood cell production)
o Haversian canal – central canal with blood vessel and nerve
o Lacuna – space where cells are located
o Canaliculi – radiate from lacuna; canal through which nutrients travel to nearby cells
o Lamellae – matrix layers of bone tissue
o Haversian system - osteon – central canal + osteocytes + lacunae + lamellae + canaliculi
Blood Tissue (vascular tissue)
o Considered a connective tissue because it consists of blood cells (formed elements), surrounded by a
nonliving fluid matrix called blood plasma
o “fibers” = soluble protein molecules that become visible only during blood clotting
o Transport vehicle for the cardiovascular system; carries nutrients, wastes, respiratory gases, etc.
o Vital in maintaining internal body homeostasis
o Formed elements include:
 ____________________ – (rbc) red blood cells; disc
shaped, lack nuclei, contain hemoglobin
protein which carries oxygen; live for 90-120 days; produced in bone marrow
 leukocytes – (wbc) white blood cells; nucleated, amoeboid movement; defense against
microorganisms; produced in bone marrow and lymphatic tissue; live for 3-300 days
 - 5 types include neutrophiles, eosinophils, basophils, lymphocytes, monocytes
 - thrombocytes – platelets – used to form
blood clots; composed of pieces of
megakaryocytes wrapped in a membrane; produced in bone marrow; live 5-7 days;
amoeboid movement
Nervous Tissue
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Branched neurons with long cellular processes and support cells
Transmits electrical signals from sensory receptors to effectors
Found in the brain, spinal cord and nerves
Composed of two kinds of cells:
1)
___________ – nerve cells; receive and conduct
electrochemical impulses from one part of the
body to
another
o - do not undergo mitosis; may occasionally repair itself
o - composed of three components:
1. Cell body – contains nucleus & organelles
o 2. Dendrites – receive stimulus and conduct impulse toward cell body
o 3. ______________ – long extension that conducts impulse away from cell body; nerve fiber
2) neuroglia – glial cells - supporting cells; insulate, support, and protect neurons
o - do not transmit impulses
o - may be phagocytic
o - may provide nourishment to neurons
Muscle Tissue – responsible for movement of food, fluids, and body parts
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Three major types:
Smooth muscle – no ______________ are visible
- found in the walls of hollow organs such as stomach, bladder, uterus, and blood vessels
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- peristaltic contractions – wavelike motion keeps food moving through the small intestine
- contraction is under involuntary control
- long, spindle-shaped with a single nucleus
Cardiac Muscle – found only in the heart
- striated, _________________ branching cells that fit tightly together at junctions called
intercalated disks
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- intercalated disks contain gap junctions that allow ions to pass freely from cell to cell, resulting
in rapid conduction of nerve impulses across heart
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- under involuntary control
o - Propels blood into the circulation
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- do not divide
o Skeletal Muscle – attached to the skeleton; move bones or skin
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- controlled voluntarily or involuntarily; gross body
movements or changes in facial
expressions
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- form flesh of the body
o
- cells are long, cylindrical, and ___________________
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- striated
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- do not divide
Epithelial Membranes: Cutaneous Membrane
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Cutaneous – skin, an organ system consisting of a keratinized squamous epithelium firmly attached to a
thick layer of dense irregular connective tissue
Epithelial Membranes: Mucous Membrane
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Tissue Trauma
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Tissue Repair
Mucous – lines body cavities open to the exterior and contain either stratified squamous or simple
columnar epithelia (e.g., digestive and respiratory tracts)
Serous – simple squamous epithelium resting on a thin layer of loose connective (areolar) tissue
Three steps are involved in the tissue repair process:
1.
___________________ prepares the area for the repair process - characterized by:
Dilation of blood vessels
Increase in vessel permeability
Redness, heat, swelling, and pain
o 2.
Organization and restored blood supply
o The blood clot is replaced with granulation tissue
o 3.
Regeneration and fibrosis
o Surface epithelium regenerates and the scab detaches
o Fibrous tissue matures and begins to resemble the adjacent tissue
o Results in a fully regenerated epithelium with underlying scar tissue
Developmental Aspects
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Primary germ layers: _______________________, mesoderm, and endoderm
Three layers of cells formed early in embryonic development
Specialize to form the four primary tissues
Nerve tissue arises from ectoderm
Muscle, connective tissue, endothelium, and mesothelium arise from mesoderm
Most mucosae arise from endoderm
Epithelial tissues arise from all three germ layers
With increasing age, epithelia become thin, the amount of collagen fibers in the body decreases, and
bone, muscle, and nervous tissue atrophy