Connective Tissue and Bone Histology Flashcards

Comprehensive practice flashcards covering connective tissue proper, specialized connective tissues (cartilage types), and bone histology based on BIO 351 lecture material.

What are the primary general characteristics of connective tissue?

Connective tissue is the most abundant tissue in the body, is vascular (with exceptions like cartilage), features cells widely scattered throughout an extracellular matrix, and does not occur on free body surfaces.

What are the four primary functions of connective tissue?

1. Binding one kind of tissue to another (loose connective tissue, tendons); 2. Support (bone and cartilage); 3. Physical protection (bones, adipose tissue); 4. Immune protection (white blood cells).

How is connective tissue classified into proper and specialized types?

Connective tissue proper includes loose (areolar), dense irregular, dense regular, elastic, reticular, and adipose tissues. Specialized connective tissue includes hyaline cartilage, elastic cartilage, fibrocartilage, bone, and blood.

What components make up the extracellular matrix (ECM) of connective tissue?

The extracellular matrix (ECM) consists of protein fibers (collagenous, elastic, reticular) and ground substance.

What is the function of fibroblasts in connective tissue proper, and what is their quiescent form called?

Fibroblasts are the most common cell type in connective tissue proper and synthesize protein fibers and ground substance. Their quiescent form is called a fibrocyte, characterized by elongated cells with thin cytoplasmic extensions.

What are the functions and origin of macrophages and mast cells in connective tissue?

Macrophages derive from blood monocytes and function as phagocytes to destroy bacteria. Mast cells are oval cells containing granules of heparin (anticoagulant) and histamine (vasodilator) that trigger and mediate inflammation.

What are the key histological features and the primary function of plasma cells?

Derived from B lymphocytes, plasma cells synthesize antibodies. Histologically, they feature a spherical, eccentric nucleus with chromatin arranged like a clock face, a pale cytoplasmic area (Golgi apparatus), and dark basophilic areas (rough endoplasmic reticulum).

How do collagenous, elastic, and reticular fibers differ in composition and appearance?

Collagenous fibers are made of collagen ('white fibers') and form the bulk of tendons and ligaments. Elastic fibers are made of elastin ('yellow fibers') and allow stretch and recoil in skin, vessel walls, and lungs. Reticular fibers are thin collagen fibers coated with glycoprotein forming a scaffold-like stroma in soft organs (spleen, lymph nodes).

What organic components form the ground substance of connective tissue?

Water, glycosaminoglycans (GAGs) such as hyaluronic acid, chondroitin sulfate, and dermatan that trap water, and proteoglycans (core proteins with attached GAGs).

What molecule is depicted in this diagram, and what are its major binding sites?

Fibronectin; it is a multiadhesive glycoprotein that binds cells to the extracellular matrix via binding sites for Integrin, proteoglycans, and collagen fibers.

What are the main characteristics and locations of loose (areolar) connective tissue?

It is widely distributed, well-vascularized, stretchable, and connects adjacent structures. Locations include the lamina propria of mucous membranes, hypodermis, serosal linings of peritoneal and pleural cavities, and superficial fascia.

Identify the tissue type and structural arrangement shown in this photomicrograph.

Dense irregular connective tissue (dermis of the skin); composed of dense, interwoven bundles of collagenous fibers arranged irregularly to withstand stresses from any direction, with fibroblast nuclei scattered throughout.

What tissue type is shown in this image, and where is it located in the human body?

Dense regular connective tissue; composed primarily of parallel collagen fibers that resist tensile stress in one direction. Found in tendons, ligaments, and aponeuroses.

What are the composition and anatomical locations of elastic connective tissue?

Composed of parallel arrangements of elastic fibers with thin collagen fibers and fibroblasts in between. Located in the yellow ligaments of the vertebral column and walls of some arteries.

How do reticular cells interact with reticular fibers in reticular connective tissue?

Reticular cells are specialized fibroblasts that partially cover branching reticular fibers with cytoplasmic processes, creating cell-lined spaces through which blood or lymph percolates.

What are the main functions and locations of adipose tissue?

Functions: Stores energy as triglycerides, provides thermal insulation, and supports/protects organs. Locations: Hypodermis, around kidneys and eyeballs, abdomen, breasts, hips, and thighs.

What are the key functional features of cartilage tissue?

Cartilage is an avascular, specialized connective tissue with a firm ECM and chondrocytes. It supports soft tissues, provides shock absorption and sliding movement in joints, and is essential for long bone growth and development.

What are the three main types of cartilage and their principal matrix fibers?

1. Hyaline Cartilage: Type II collagen; 2. Elastic Cartilage: Type II collagen and abundant elastic fibers; 3. Fibrocartilage: Dense matrix of coarse Type I collagen fibers.

What is the perichondrium, and which cartilage types lack it?

The perichondrium is a sheath of dense connective tissue containing blood vessels, nerves, and lymphatic vessels surrounding cartilage. Fibrocartilage and articular cartilage (a type of hyaline cartilage) lack a perichondrium.

Describe the stages (A–D) of cartilage histogenesis shown in this figure.

A. Embryonic mesenchyme; B. Mitotic proliferation of mesenchymal cells; C. Differentiation into chondroblasts laying down matrix; D. Multiplication yielding chondrocytes surrounded by territorial (capsular) matrix (superficial mesenchyme forms perichondrium).

What are isogenous groups and territorial matrix in hyaline cartilage?

Isogenous groups are clusters of rounder chondrocytes formed by mitotic divisions of a single chondrocyte. Territorial (capsular) matrix is the zone immediately surrounding chondrocytes that is rich in GAGs but poor in collagen.

What are four major anatomical locations of hyaline cartilage?

Articular surfaces of bones, respiratory tract (nose, larynx, trachea, bronchi), sternal ends of ribs (costal cartilage), and epiphyseal ('growth') plates of bones.

Where is elastic cartilage found in the human body?

Auricle/pinna of the ear, walls of the external auditory canals, eustachian tubes, and the epiglottis.

What are the key histological features and locations of fibrocartilage?

Features: Chondrocytes single or in long rows separated by coarse Type I collagen fibers; lacks a perichondrium; capsules seldom seen. Locations: Intervertebral discs, pubic symphysis, and menisci of knees.

According to the provided logic tree, how do you differentiate between cartilage types?

If matrix is homogenous with randomly arranged lacunae = Hyaline cartilage. If matrix contains fibers that are randomly arranged = Elastic cartilage. If matrix contains fibers that are NOT randomly arranged = Fibrous cartilage.

What are the three main cell types in bone tissue and their specific roles?

1. Osteoblasts: Synthesize and secrete osteoid (uncalcified bone matrix); 2. Osteocytes: Mature bone cells housed within lacunae; 3. Osteoclasts: Large multinuclear cells that perform osteolysis (bone resorption).

What are the organic and inorganic components of bone matrix?

Organic: Type I collagen fibers and ground substance (chondroitin sulfate and keratan sulfate). Inorganic: Calcium and phosphate forming hydroxyapatite crystals, amorphous calcium phosphate, and ions (bicarbonate, citrate, magnesium, potassium, sodium).

How do compact bone and spongy bone differ structurally?

Compact bone forms dense areas without internal cavities. Spongy (cancellous) bone contains numerous interconnecting cavities separated by flat or needle-like bony partitions called trabeculae.

What are the key structural components of a Haversian system (osteon) in compact bone?

A central (Haversian) canal containing blood vessels, surrounded by concentric lamellae, lacunae containing osteocytes, and radiating canaliculi. Transverse Volkmann's (perforating) canals connect adjacent central canals.

What membrane covers the external surface of bone, and what membrane lines internal canals and trabeculae?

The periosteum covers the external bone surface (anchored by Sharpey's/perforating fibers); the endosteum lines internal canals (Haversian and Volkmann's) and covers the trabeculae of spongy bone.

What effect does the blockage of central (Haversian) canals have on surrounding osteocytes as people age?

Blocking the central canal cuts off the supply of oxygen and nutrients delivered via blood vessels to osteocytes through canaliculi, causing the surrounding osteocytes to degenerate or die.