Histology: Introduction to Tissues, Epithelium, Connective Tissue, Cartilage, Muscle, and Nerve

A set of practice flashcards covering histology concepts from the provided lecture notes, formatted as question-and-answer.

What is histology?

The science that deals with the study of tissues.

What are tissues?

Groups of cells similar in structure, function, and embryonic origin; a tissue consists of cells and an extracellular matrix.

Name the four major tissue types.

Epithelium, Connective tissue, Muscle, Nervous tissue.

What is the primary role of epithelium?

To cover or line all external and internal body surfaces and to form glands.

Give examples of epithelial covering/lining and glandular epithelium.

Covering/lining: epidermis and lining of the intestine; Glandular: sweat glands, sebaceous glands, pancreas, etc.

What does connective tissue do?

Connects and supports body parts (e.g., bones, tendons, ligaments) and includes fat, blood, and other tissues.

What is the function of muscle tissue?

Contracts to move body parts.

What is the function of nervous tissue?

Transmits nerve impulses.

What is a biopsy?

Removal of living tissue for microscopic examination to diagnose disease.

What is a pathologist?

A physician who studies tissue cells to diagnose disease and may perform autopsies.

What are the three primary germ layers formed after implantation?

Endoderm, Mesoderm, and Ectoderm.

What does the ectoderm form?

Epidermis and the nervous system (brain and spinal cord), plus skin glands.

What does the mesoderm form?

Mesenchymal cells that give rise to muscle, bone, blood; dermis; and walls of digestive and respiratory tracts.

What does the endoderm form?

Mucous membranes of the digestive and respiratory tracts and the digestive glands.

What is epithelium?

A sheet of tightly packed cells attached to a basement membrane that covers/lines surfaces and makes up glands.

What are the two main epithelial types by function?

Covering/lining epithelia and glandular epithelia.

What is a basement membrane?

A noncellular, gel-like layer with basal lamina and reticular lamina that anchors epithelium to connective tissue.

What is epithelial polarity?

Having apical (top) and basal (bottom) surfaces that are structurally and functionally different.

What are desmosomes?

Protein fibers that link adjacent cell membranes to strengthen tissue; common in stratified epithelia.

What are tight junctions?

Protein fibers that fuse adjacent cell membranes and seal the space between cells, preventing leakage.

Are epithelial tissues vascularized?

No; they are avascular and nutrients diffuse from underlying connective tissue.

What are microvilli?

Tiny apical projections that increase surface area (15–40x) for absorption; not motile.

What are cilia and their function?

Long apical projections (7–10 μm) that beat to move mucus and debris; part of the mucociliary escalator.

What is the basement membrane composed of?

Basal lamina and reticular lamina that anchor epithelium to connective tissue.

What is epithelial cell polarity in terms of surfaces?

The apical surface faces the free surface; the basal surface faces the basement membrane.

What is pseudostratified columnar epithelium?

A single layer of cells of varying heights that appears stratified; often with cilia and goblet cells.

What is simple squamous epithelium?

A single layer of flat, thin cells; allows rapid diffusion and filtration (e.g., alveoli, capillaries).

What is simple cuboidal epithelium?

A single layer of cube-shaped cells; located in kidney tubules; function: secretion and absorption.

What is simple columnar epithelium?

A single layer of tall, column-shaped cells; lines the stomach and intestines; may have goblet cells and microvilli.

What is stratified squamous epithelium and its subtypes?

Multiple cell layers; keratinized (skin) and nonkeratinized (mouth, esophagus, vagina).

What are mucous membranes?

Epithelial membranes with goblet cells that secrete mucus; line hollow organs that open to the exterior.

What are serous membranes?

Serosa: a single layer of squamous cells on areolar CT; secrete serous fluid to reduce friction; includes peritoneum, pericardium, pleura; mesothelium forms the serous layer.

What is endothelium?

Single layer of simple squamous epithelium lining hollow cardiovascular and lymphatic organs (vessels and heart chambers).

What are goblet cells?

Unicellular glands that secrete mucin to form mucus; protect and lubricate mucous membranes.

What is endocrine gland function?

Multicellular glands that secrete hormones directly into the bloodstream.

What is exocrine gland function?

Multicellular glands that secrete into ducts that open onto surfaces or into hollow organs.

What is merocrine secretion?

Secretions released by exocytosis without cell destruction (e.g., salivary, sweat, pancreatic).

What is holocrine secretion?

Secretions released after the gland cell ruptures and dies; the entire cell disintegrates (e.g., sebaceous glands).

What are the three major connective tissue fiber types?

Collagen, Elastic, and Reticular fibers.

What is collagen and its properties?

The most abundant protein; provides high tensile strength; resistant to stretch; requires vitamin C for synthesis.

What is elastic tissue?

Elastic fibers that allow stretch and recoil; can stretch up to ~150% of length.

What are reticular fibers?

Thin collagen-type fibers forming a supportive mesh in glands and lymphoid organs.

What is ground substance in connective tissue?

The gel-like intercellular material between cells, containing interstitial fluid, carbohydrates, and proteins.

What cells are found in connective tissue?

Fibroblasts, macrophages, neutrophils, mast cells, adipocytes.

What is areolar (loose) connective tissue?

Widely scattered cells (mostly fibroblasts) in a loose matrix; sits beneath epithelia and around vessels; well vascularized.

What is adipose tissue?

Dense aggregation of adipocytes storing fat as triglycerides; insulates, protects, and stores energy; secretes hormones.

What is reticular connective tissue?

Mesh of reticular fibers forming a supportive framework in organs like liver and spleen.

What are the three types of cartilage?

Hyaline, Elastic, Fibrocartilage.

What is perichondrium?

Dense connective tissue surrounding most cartilage (vascular for elastic and hyaline; absent in fibrocartilage).

What is hyaline cartilage?

Clear matrix with fine collagen; most abundant cartilage; locations include articular surfaces, embryonic skeleton, costal cartilage, tracheal rings, larynx, and nose tip.

What is elastic cartilage?

Cartilage with elastic fibers; highly flexible; locations include external ear (pinna) and epiglottis.

What is fibrocartilage?

Cartilage with thick collagen fibers; very strong and slightly compressible; located in intervertebral disks and menisci.

What is bone tissue?

Osseous tissue with osteocytes in a mineralized matrix containing collagen and calcium phosphate; compact and spongy types.

What is blood considered in connective tissue terms?

A connective tissue with a fluid matrix (plasma) and formed elements (RBCs, WBCs, platelets); lacks collagen/elastic fibers in the matrix.

What are the three types of muscle tissue and their key features?

Skeletal: attached to bone, striated, voluntary, multinucleate; Cardiac: in heart, striated, involuntary, usually uni- or bi-nucleate, branched with intercalated disks; Smooth: in hollow organs, non-striated, involuntary, uninucleate.

What are sarcolemma and sarcoplasm?

Sarcolemma is the plasma membrane of a muscle cell; sarcoplasm is the cytoplasm of a muscle cell.

What are neurons?

Nerve cells specialized to generate and transmit nerve impulses; basic structure includes soma, dendrites, and a single axon.