A&P Chapter 5: Tissue Types, Classification, and Functions

Flashcards covering key definitions, tissue classification, cellular junctions, connective tissues, muscle types, nervous tissue, membranes, inflammation, repair, aging, and cancer from A&P Chapter 5.

What is a tissue?

A group of cells functioning together in the body.

What is histology?

The microscopic study of tissue appearance, organization, and function.

What are the 4 major tissue types in the human body?

1. Epithelial
2. Connective
3. Muscle
4. Nervous

What is the primary function of epithelial tissue?

Covers/protects surfaces, lines cavities and passageways, and forms glands.

What is the primary function of connective tissue?

Connects, supports, protects, and integrates tissues and organs.

What is the primary function of muscle tissue?

Contraction and movement.

What is the primary function of nervous tissue?

Communication throughout the body.

What is the extracellular matrix (ECM)?

A network of substances surrounding and supporting cells in a tissue.

What are the 2 major components of the extracellular matrix (ECM)?

Collagen fibers and proteoglycans.

What is collagen and why is it significant in the human body?

Collagen is a strong protein that forms tough fibers and provides structural support; it is the most abundant protein in the human body.

What are proteoglycans?

Molecules made of carbohydrate and protein that attract water and help create a gel-like ECM.

What are the 3 basic types of cell junctions?

Tight junctions, anchoring junctions/desmosomes, and gap junctions.

What is the function of a tight junction and where is it especially important?

It seals neighboring cells together to prevent substances from passing between them; it is especially important in intestinal epithelium to prevent bacteria from passing between cells.

What is the difference between a desmosome and a hemidesmosome?

A desmosome is an anchoring junction that strongly connects two neighboring cells, whereas a hemidesmosome connects a cell to the extracellular matrix.

What is the function of gap junctions and why are they vital in cardiac muscle?

They allow small molecules and ions to pass directly between neighboring cells; in cardiac muscle, they allow electrical signals to pass between cells to coordinate heart contractions.

What are the major structural and functional characteristics of epithelial tissue?

Highly cellular, polarized, avascular, innervated, attached to a basement membrane, and highly regenerative.

What does 'polarized' mean in the context of epithelial cells?

It means epithelial cells have distinct apical (facing external environment or lumen) and basal (facing ECM/underlying tissue) surfaces.

What are the two layers of the basement membrane and their functions?

1. Lamina lucida: provides immediate attachment site for epithelial cells.
2. Lamina densa: provides structural support and connects epithelium to underlying connective tissue.

How do epithelial tissues receive oxygen and nutrients if they are avascular?

By diffusion from underlying vascularized connective tissue.

What is the functional difference between cilia and microvilli?

Cilia are motile and move fluid/particles across the epithelial surface, while microvilli increase surface area for absorption and transport.

How is epithelial tissue classified?

By the number of cell layers (simple vs. stratified) and cell shape (squamous, cuboidal, columnar).

What is pseudostratified columnar epithelium?

A single layer of columnar cells that appears to have multiple layers because the cells and nuclei are at different heights, though all cells contact the basement membrane.

What is transitional epithelium and where is it located?

Specialized stratified epithelium that changes cell shape as it stretches; found in the urinary bladder, ureters, and urethra.

Where are simple squamous, simple cuboidal, and simple columnar epithelia located in the body?

Simple squamous: lung air sacs, capillaries, blood/lymphatic vessels, lining of heart. Simple cuboidal: kidney tubules and ducts of small glands. Simple columnar: digestive tract and parts of reproductive tract.

What is the difference between keratinized and nonkeratinized stratified squamous epithelium?

Keratinized epithelium has apical layers containing dead, keratin-filled cells (found in skin); nonkeratinized epithelium has apical cells that remain living and moist (found in mouth, esophagus, vagina).

What are goblet cells?

Unicellular exocrine glands that secrete mucus, commonly found in columnar epithelium of respiratory and mucous membranes.

How do endocrine and exocrine glands differ in their secretion delivery?

Endocrine glands are ductless and release hormones directly into surrounding interstitial fluid/bloodstream; exocrine glands release secretions onto an epithelial surface through a duct.

What are the 3 methods of exocrine gland secretion?

1. Merocrine: secretion by exocytosis with no cell loss (most common).
2. Apocrine: apical portion of the cell detaches with secretion.
3. Holocrine: entire secretory cell is destroyed and becomes part of the secretion.

What are the 3 major components of connective tissue?

Cells, ground substance, and protein fibers.

What is the primary cell type in connective tissue proper and what does it produce?

The fibroblast; it produces connective tissue fibers and ground substance.

What functions are provided by collagen, elastic, and reticular fibers?

Collagen fibers provide tensile strength and resistance to stretching; elastic fibers provide elasticity to return to shape; reticular fibers form a thin, branching supportive network.

What is the difference between dense regular and dense irregular connective tissue?

Dense regular has parallel collagen fibers designed to resist pulling forces in one direction (e.g., tendons); dense irregular has collagen fibers arranged in multiple directions to resist forces from many directions (e.g., deep skin).

Why does cartilage heal much slower than bone?

Cartilage is avascular and relies on diffusion through its matrix for nutrients, whereas bone is highly vascularized.

What are the 3 types of cartilage and key locations for each?

1. Hyaline cartilage: nose, rib cartilage, joint surfaces.
2. Fibrocartilage: intervertebral discs, pubic symphysis, knee meniscus.
3. Elastic cartilage: external ear.

Why is blood classified as a connective tissue?

Because it consists of cells (erythrocytes, leukocytes, platelets) suspended in an extracellular fluid matrix called plasma.

How do skeletal, cardiac, and smooth muscle compare regarding voluntary control, striations, nucleus count, and location?

Skeletal: Voluntary, Striated, Many nuclei, attached to Bones. Cardiac: Involuntary, Striated, Usually 1 nucleus, located in Heart. Smooth: Involuntary, Not striated, 1 nucleus, located in Hollow organs.

What is an intercalated disc?

A specialized junction between cardiac muscle cells containing desmosomes and gap junctions that coordinate heart contractions.

What are the two major cell types in nervous tissue and their primary functions?

Neurons (receive/respond to stimuli and transmit electrochemical signals) and Glial cells (support, protect, and enable neuron function).

What are dendrites and axons?

Dendrites are short neuronal branches that receive incoming signals; an axon is a long process that sends signals away to target cells.

What are the 4 tissue membranes found in the human body?

1. Mucous membranes (open to outside)
2. Serous membranes (line closed body cavities)
3. Cutaneous membrane (skin)
4. Synovial membranes (line freely movable joint cavities)

What chemical signal causes vasodilation and increased permeability during tissue inflammation?

Histamine.

What are the 4 cardinal signs of tissue inflammation?

Heat, Pain, Redness, and Swelling (edema).

What is angiogenesis and why is it necessary during tissue repair?

Angiogenesis is the growth of new blood vessels; it revascularizes newly formed repair tissue with oxygen and nutrients.

What happens to tissue elasticity and cell replication as the body ages?

Elastic fibers decrease (reducing elasticity), and cell mitotic capacity decreases, slowing tissue healing.

What is the difference between a benign tumor, a malignant tumor, and metastasis?

A benign tumor does not metastasize or invade other tissues; a malignant tumor is cancerous and invades nearby tissue; metastasis is the spread of cancer cells to other parts of the body.

What are carcinomas, sarcomas, leukemias, and myelomas?

Carcinomas: cancers of epithelial cells. Sarcomas: cancers of connective tissue. Leukemias: cancers of white blood cells. Myelomas: cancers of myeloid tissue/blood cells.