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Questions and Answers
How are epithelial tissues classified, and why is this classification important for understanding their function?
How are epithelial tissues classified, and why is this classification important for understanding their function?
Epithelial tissues are classified by the shape of their cells (squamous, cuboidal, columnar, transitional) and the number of cell layers (simple, stratified, pseudostratified). This classification relates to function because cell shape and layering are adapted to specific roles, such as protection (stratified), absorption (columnar), or diffusion (simple squamous).
Compare and contrast endocrine and exocrine glands, providing an example of each and explaining how their structural differences relate to their function.
Compare and contrast endocrine and exocrine glands, providing an example of each and explaining how their structural differences relate to their function.
Endocrine glands secrete hormones directly into the bloodstream and lack ducts (e.g., thyroid gland), while exocrine glands secrete substances through ducts onto a surface or into a cavity (e.g., sweat glands). This structural difference dictates that endocrine secretions have systemic effects, while exocrine secretions have localized effects.
Describe the roles of fibroblasts, chondrocytes, and osteocytes in connective tissues, and explain how their functions contribute to the overall properties of these tissues.
Describe the roles of fibroblasts, chondrocytes, and osteocytes in connective tissues, and explain how their functions contribute to the overall properties of these tissues.
Fibroblasts produce the fibers and ground substance in connective tissue proper, providing support and structure. Chondrocytes maintain cartilage, providing flexible support. Osteocytes maintain bone matrix, giving bones rigidity and strength. The cells' functions determine the tissue's overall properties.
Explain how the arrangement and characteristics of collagen and elastic fibers in dense connective tissue contribute to the tissue's function and where these tissues are typically found.
Explain how the arrangement and characteristics of collagen and elastic fibers in dense connective tissue contribute to the tissue's function and where these tissues are typically found.
Contrast the structural and functional differences between skeletal, smooth, and cardiac muscle tissues.
Contrast the structural and functional differences between skeletal, smooth, and cardiac muscle tissues.
Explain the roles of neurons and neuroglia in nervous tissue, and how their interaction enables the nervous system to function.
Explain the roles of neurons and neuroglia in nervous tissue, and how their interaction enables the nervous system to function.
Describe the key functions of mucous and serous membranes, and explain how their structural differences allow them to perform these functions effectively.
Describe the key functions of mucous and serous membranes, and explain how their structural differences allow them to perform these functions effectively.
Outline the steps and symptoms of the inflammation process and explain its role in tissue repair.
Outline the steps and symptoms of the inflammation process and explain its role in tissue repair.
Compare and contrast tissue repair by regeneration and replacement, and explain circumstances under which each process is likely to occur.
Compare and contrast tissue repair by regeneration and replacement, and explain circumstances under which each process is likely to occur.
How do the embryonic germ layers (endoderm, mesoderm, and ectoderm) contribute to the formation of different tissue types in the body?
How do the embryonic germ layers (endoderm, mesoderm, and ectoderm) contribute to the formation of different tissue types in the body?
Flashcards
What are tissues?
What are tissues?
Collections of similar cells and the extracellular matrix surrounding them.
Four Primary Tissue Types
Four Primary Tissue Types
Epithelial, connective, muscle, and nervous tissue.
Epithelial Tissue
Epithelial Tissue
Covers surfaces, has little extracellular material, and usually has a basement membrane.
Functions of Epithelial Tissue
Functions of Epithelial Tissue
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Epithelial Tissue Cell Shapes
Epithelial Tissue Cell Shapes
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Epithelial Cell Number
Epithelial Cell Number
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Connective Tissue Cells
Connective Tissue Cells
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Classification of Connective Tissue
Classification of Connective Tissue
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Main Function of Muscle Tissue
Main Function of Muscle Tissue
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Three Types of Muscle Tissue
Three Types of Muscle Tissue
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Study Notes
- Tissues are collections of similar cells and the extracellular matrix surrounding them; the study of tissues is histology
- There are four primary tissue types: epithelial, connective, muscle, and nervous tissue
- Primary tissue types derive from the embryonic germ layers: endoderm, mesoderm, and ectoderm
Embryonic Germ Layers
- Endoderm forms the lining of the digestive tract and its derivatives
- Mesoderm forms tissues such as muscle, bone, and blood vessels
- Ectoderm forms the outermost layer of skin and the nervous system
Epithelial Tissue
- Covers surfaces
- Has little extracellular material
- Usually has a basement membrane and no blood vessels
- Cells have a free, or apical surface (not attached to other cells), a lateral surface (attached to other cells), and a basal surface (attached to the basement membrane)
- Cells are bound tightly together
- Little extracellular material
- Arranged in sheets
- Cover internal and external surfaces
- Often controls the passage of material
Epithelial Tissue Functions
- Protects underlying structures like the outer layer of skin and oral mucosa
- Acts as barriers like the outer layer of skin
- Permits the passage of substances like epithelium in the lungs
- Secretes substances like mucous and sweat glands
- Absorbs substances like epithelial cells of the intestine
- Classified by shape of cells and number of layers
Epithelial Tissue Cell Shape
- Squamous is thin, flat cells that look like fried eggs
- Cuboidal is square-shaped in cross-section and 6-sided polygons on the surface
- Columnar is rectangular in cross-section and polygonal on the surface view
Epithelial Cell Number
- Simple is a single layer
- Stratified is 2+ layers
- Pseudostratified appears stratified but is not
- Transitional changes shape
Epithelial Tissue Classification
- Epithelia are classified according to the number of cell layers and the shape of the cells
- Simple epithelium has one layer of cells like simple squamous, cuboidal, and columnar
- Stratified epithelium has more than one cell layer like stratified squamous (non-keratinized/moist and keratinized), cuboidal (rare), and columnar (rare)
- Pseudo-stratified epithelium has one layer but appears to have two or more layers
- Transitional epithelium is stratified, capable of great stretching (from cuboidal to squamous)
- Simple squamous epithelium is a single layer of squamous shape lining the body cavity, lungs, and blood vessels
- Simple cuboidal epithelium is a single layer of cuboidal shaped cells lining kidney tubules and glands
- Simple columnar epithelium is a single layer of columnar-shaped cells lining the digestive tract, and it is modified by the presence of cilia
- Stratified squamous epithelium is multi-layered with outermost layers of squamous cells and inner layers of cuboidal or columnar cells lining the mouth, esophagus, and skin
- Pseudo-stratified columnar epithelium is one layer that appears stratified lining the respiratory tract
Structural and Functional Relationships
- Simple epithelium is involved with diffusion, secretion, and absorption
- Stratified epithelium serves a protective role
- Squamous cells function in diffusion and filtration
- Cuboidal or columnar cells contain cellular organelles, secrete, and absorb
- Free cell surfaces are smooth, which reduces friction and lines blood vessels
- Microvilli are cylindrical extensions of the cell membrane that increase the surface area like the lining of the small intestine
- Cilia propel materials over the cell surface like the lining of the nasal cavity and trachea
Glands In Epithelial Tissue
- A gland is a single cell or multicellular structure that secretes
- Endocrine glands do not have ducts; they secrete hormones directly into the blood
- Exocrine glands have ducts and secretions which are released onto a surface or into a cavity
Structure Of Exocrine Glands
- Simple glands have one duct
- Compound glands have ducts that branch repeatedly
- Tubules have ducts that end in small tubes
- Acini have ducts that end in saclike structures
- Alveoli have ducts that end in hollow sacs
Exocrine Glands & Secretion Types
- Merocrine glands have no loss of cellular material like sweat glands
- Apocrine glands have part of the cell pinches off like mammary glands
- Holocrine glands have the entire cell shed
- Sweat and mammary glands are classified by structure, and how products leave the cell
Connective Tissue
- Has abundant extracellular material matrix (dominant part) fiber, cells in liquid, gel, or solid matrix
- Functions to bind and/or support other tissues
- Consists of cells separated from each other by abundant extracellular matrix and functions to enclose, separate, and connect tissues to one another
Connective Tissue Functions
- Enclosing and separating
- Connecting tissues to one another (ligaments and tendons)
- Supporting and moving (bones and cartilage)
- Storing (adipose tissue and bones)
- Cushioning and insulating (adipose tissue)
- Transporting (blood)
- Protecting (blood and bones)
Connective Tissue Cells
- Specialized cells of various connective tissues produce the extracellular matrix; they end in suffixes that identify the cell functions
- Blast (germ) cells form the matrix
- Cyte (cell) cells maintain it
- Clast (break) cells break it down
Classification of Connective Tissue
- Mesenchyme is an embryonic connective tissue that gives rise to six major categories of connective tissue
- Loose, or areolar, connective tissue is the "loose packing" material of the body
- Fills the spaces between organs and holds organs in place
- Adipose tissue (fat) stores energy, pads and protects parts of the body, and acts as a thermal insulator
- Dense connective tissue consists of a matrix containing densely packed fibers
- Collagen fibers (tendons, ligaments, dermis of the skin)
- Elastic fibers (elastic ligaments and in the walls of arteries)
Connective Tissue Support
- Cartilage provides support:
- Hyaline cartilage covers the ends of bones and forms costal cartilages
- Fibrocartilage is in disks between vertebrae -Elastic cartilage is in the external ear
Connective Tissue Matrix
- Bone has a mineralized matrix which forms most of the skeleton of the body
- Compact bone has more matrix than spaces
- Cancellous bone has more spaces than matrix
- Blood has a liquid matrix, found in blood vessels and produced in hematopoietic tissue (red bone marrow)
- Connective tissue proper is composed of a matrix of fibers; loose or areolar with few and delicate fibers; fibrous is abundant, well-organized fiber
- Adipose Tissue has loose connective and stores large droplets of fat
- Blood contains lymph, and is in a liquid matrix which is sometimes categorized differently containing RBC-red blood cells and WBC-white blood cells
- Cartilage contains chondrocytes, small cavities (lacunae), and has a rubbery consistency (matrix) in the ear and nose
- Bone contains osteocytes, small cavities (lacunae), is the hardest CT, and is impregnated with calcium salts, spongy (loose rods of bones, ends of arms and legs), and compact (*shafts of long bones, *tightly organized)
Muscle Tissue
- Main function is to contract or shorten making movement possible
- Three types of muscle tissue: skeletal, smooth, and cardiac
- Skeletal: voluntary movement, long and cylindrical, transverse striation, and each fiber is multinuclear
- Smooth: involuntary movement, predominant, long spindle shape, single nucleus, internal organs
- Cardiac: striations, involuntary, one nucleus
Nervous Tissue
- Nerve tissue cells have a very high ability to respond to stimuli and transmit impulses
- The neuron contains a cell body, dendrites receive electrical impulses from other neurons, and an axon transmits electrical impulses to other neurons
Nervous Tissue Function
- Brain, SC, Ganglia/ Spinal Nerves, and it is specializes in conducting action potentials (electrical signals)
- Neurons conduct action potentials; neuroglia support the neurons and surround neurons
- Neurons have 3 parts:Cell Body- contains the nucleus
Membranes
- Mucous membranes line cavities that open to the outside of the body, like the digestive, respiratory, urinary, and reproductive tracts; they contain glands and secrete mucus
- Serous membranes like the trunk cavities that do not open to the outside of the body, such as the pleural, pericardial, and peritoneal cavities; they do not contain glands and secrete serous fluid
- Synovial membranes line freely movable joints
Inflammation Process
- The function of the inflammatory response is to mobilize the body's defenses, isolate, and destroy harmful agents
- Five symptoms: redness, heat, swelling, pain, and disturbance of function
- Chronic inflammation results when the agent causing injury is not removed or something else interferes with the healing process
Tissue Repair
- Tissue repair is the substitution of viable cells for dead cells by regeneration/reconstruction where dead tissues are replaced with the same type of cell (skin, liver cells)
- Replacement is when a new type of tissue develops that eventually causes scar production and loss of some tissue function
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Description
Explore tissues as collections of similar cells and their surrounding matrix, a field studied in histology. Discover the four primary tissue types—epithelial, connective, muscle, and nervous—derived from embryonic germ layers: endoderm, mesoderm, and ectoderm. Learn how these layers form crucial body structures.
