BIOL 214 Exam 2: Histology, Skin & Bone Tissues

What are the four primary types of adult tissues?

Epithelial tissue, connective tissue, muscular tissue, and nervous tissue.

What is an organ?

A structure composed of two or more tissue types that performs specific functions.

What are the three embryonic germ layers?

Ectoderm, mesoderm, and endoderm.

What tissues develop from the ectoderm?

The epidermis of the skin and much of the nervous system.

What tissues develop from the mesoderm?

Examples include muscle, bone, cartilage, blood, and many connective tissues.

What tissues develop from the endoderm?

Examples include the epithelial linings of much of the digestive and respiratory tracts and associated glands.

What is histology?

The study of tissues.

What is fixation in tissue preparation?

Preserving tissue so it does not decay and its structures remain as close to their original state as possible.

Why are tissue samples stained?

To increase contrast and make different cells and structures easier to see.

What is a longitudinal section?

A tissue cut lengthwise along the long axis of a structure.

What is a transverse section?

A tissue cut across the structure, perpendicular to its long axis.

What is an oblique section?

A tissue cut at an angle to the long axis.

Why can the same structure look different in different tissue sections?

Because the appearance depends on the angle and plane in which the tissue was cut.

What are the main functions of epithelial tissue?

Protection, absorption, secretion, excretion, filtration, and sensation.

What are the main characteristics of epithelial tissue?

Its cells are closely packed, have little extracellular matrix, have an apical and basal surface, attach to a basement membrane, lack blood vessels, and usually regenerate relatively quickly.

What does it mean that epithelium is avascular?

It contains no blood vessels. It receives nutrients by diffusion from underlying tissues.

What is the apical surface of an epithelial cell?

The free surface facing the outside of the body, a body cavity, or the inside of a hollow organ.

What is the basal surface of an epithelial cell?

The surface attached to the basement membrane.

What is the basement membrane?

A thin supporting layer that anchors epithelium to the underlying connective tissue.

What is the difference between simple and stratified epithelium?

Simple epithelium has one cell layer; stratified epithelium has multiple layers.

What does the term pseudostratified mean?

The tissue appears to have multiple layers, but all cells contact the basement membrane.

What determines the name of an epithelial tissue?

The number of cell layers and the shape of the cells at the apical surface.

What are the three basic epithelial cell shapes?

Squamous, cuboidal, and columnar.

What does squamous mean?

Flat, thin cells.

What does cuboidal mean?

Cells that are approximately as tall as they are wide.

What does columnar mean?

Cells that are taller than they are wide.

What are goblet cells?

Specialized epithelial cells that secrete mucus.

What are the eight commonly classified epithelial types?

Simple squamous, simple cuboidal, simple columnar, pseudostratified columnar, stratified squamous, stratified cuboidal, stratified columnar, and transitional epithelium.

What are the main functions of simple squamous epithelium?

Rapid diffusion, filtration, and reducing friction.

Where is simple squamous epithelium found?

In the alveoli of the lungs, kidney glomeruli, blood vessel linings, and serous membranes.

What is endothelium?

Simple squamous epithelium lining the inside of blood vessels and the heart.

What is mesothelium?

Simple squamous epithelium forming the lining of serous body cavities and covering many organs.

What are the main functions of simple cuboidal epithelium?

Secretion and absorption.

Where is simple cuboidal epithelium found?

In kidney tubules and in portions of glands and their ducts.

What are the main functions of simple columnar epithelium?

Absorption and secretion.

Where is simple columnar epithelium found?

In much of the digestive tract and in some reproductive tract structures.

What is the function of cilia on epithelial cells?

Cilia move material along the cell surface, such as mucus in the respiratory tract.

Where is ciliated pseudostratified columnar epithelium commonly found?

In much of the respiratory tract.

What is the main function of stratified squamous epithelium?

Protection against abrasion.

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

Keratinized epithelium has a surface layer of dead, keratin-filled cells that helps resist water loss and abrasion. Nonkeratinized epithelium has living cells at the surface and remains moist.

Where is keratinized stratified squamous epithelium found?

In the epidermis of the skin.

Where is nonkeratinized stratified squamous epithelium found?

In moist surfaces such as the mouth, esophagus, and vagina.

What is the main function of stratified cuboidal epithelium?

Protection and reinforcement of ducts, with some secretion and absorption.

Where is stratified cuboidal epithelium found?

In certain larger ducts of glands, including sweat glands.

What is transitional epithelium specialized for?

Stretching as organs expand and recoil as they empty.

Where is transitional epithelium found?

In the urinary tract, including the urinary bladder and ureters.

What is the main function of stratified columnar epithelium?

Protection and secretion in certain specialized passages and ducts.

What is a gland?

A cell or group of cells that produces and secretes a substance.

What is the difference between endocrine and exocrine glands?

Endocrine glands release hormones into the tissue fluid and blood without ducts. Exocrine glands release their products onto a surface or into a passage, usually through ducts.

What are the main functions of connective tissue?

Binding and support, protection, insulation, energy storage, transport, and immune defense.

What are the two main components of connective tissue?

Cells and extracellular matrix.

What makes up the extracellular matrix (ECM)?

Ground substance and protein fibers.

What are the three main types of connective tissue fibers?

Collagen fibers, elastic fibers, and reticular fibers.

What is the function of collagen fibers?

They provide tensile strength and resist pulling forces.

What is the function of elastic fibers?

They allow tissues to stretch and recoil.

What is the function of reticular fibers?

They form a supportive network around cells and within certain organs.

What is ground substance?

The material between cells and fibers in the extracellular matrix. It helps support cells and allows substances to move through the matrix.

What do fibroblasts do?

They produce connective tissue fibers and ground substance.

What do macrophages do?

They engulf and digest pathogens, damaged cells, and cellular debris.

What do mast cells do?

They release substances such as histamine that contribute to inflammation and allergic responses.

What do adipocytes do?

They store fat for energy, insulation, and cushioning.

What is the difference between loose and dense connective tissue?

Loose connective tissue has more ground substance and more loosely arranged fibers. Dense connective tissue has densely packed fibers.

What are the main characteristics of areolar connective tissue?

It has loosely arranged collagen and elastic fibers, abundant ground substance, and several cell types.

What are the functions and locations of areolar connective tissue?

It wraps and cushions organs, binds tissues, and is found beneath epithelia and around structures such as blood vessels and nerves.

What are the functions and locations of adipose tissue?

It stores energy, insulates, and cushions organs.

What are the functions of adipose tissue?

It stores energy, insulates, and cushions organs.

Where is adipose tissue found?

Beneath the skin and around organs such as the kidneys and heart.

What is the function of reticular connective tissue?

It forms a supportive framework for cells in certain organs.

Where is reticular connective tissue found?

In organs such as lymph nodes, the spleen, and bone marrow.

What are the characteristics of dense regular connective tissue?

It contains closely packed, parallel collagen fibers and resists pulling forces mainly in one direction.

Where is dense regular connective tissue found?

In tendons and most ligaments.

What are the characteristics of dense irregular connective tissue?

Its collagen fibers are arranged in multiple directions, allowing it to resist stress from different directions.

Where is dense irregular connective tissue found?

In the dermis of the skin and in fibrous capsules surrounding organs and joints.

What is elastic connective tissue specialized for?

Stretching and returning to its original shape.

Where is elastic connective tissue found?

In the walls of large arteries and certain ligaments.

What are the three major types of cartilage?

Hyaline cartilage, elastic cartilage, and fibrocartilage.

What are chondrocytes?

Mature cartilage cells that maintain the cartilage matrix.

What are lacunae?

Small spaces in the matrix that contain cells such as chondrocytes.

What are the characteristics and functions of hyaline cartilage?

It has a smooth, glassy-looking matrix that provides support and helps reduce friction at joints.

Where is hyaline cartilage found?

At the ends of bones in joints, in the nose, and in structures such as the trachea.

What are the characteristics and functions of elastic cartilage?

It contains abundant elastic fibers and provides flexible support.

Where is elastic cartilage found?

In the external ear and epiglottis.

What are the characteristics and functions of fibrocartilage?

It contains abundant collagen fibers and resists compression and pulling forces.

Where is fibrocartilage found?

In intervertebral discs, the pubic symphysis, and the menisci of the knee.

Why does cartilage heal slowly?

Cartilage is avascular, meaning it lacks blood vessels, so nutrients reach its cells by diffusion.

What are the main components of blood as connective tissue?

Plasma and formed elements: red blood cells, white blood cells, and platelets.

What is the function of plasma?

It transports substances such as nutrients, hormones, wastes, and proteins.

What is the function of red blood cells?

They transport oxygen and help transport carbon dioxide.

What is the function of white blood cells?

They help defend the body against pathogens and other threats.

What is the function of platelets?

They help blood clot.

What are the two major types of bone tissue?

Compact bone and spongy bone.

What are the major functions of bone tissue?

Support, protection, movement, mineral storage, and blood cell production in bone marrow.

What makes nervous and muscular tissues excitable?

They can respond to stimuli by changing their electrical state.

What are the two main cell types in nervous tissue?

Neurons and neuroglia.

What is the function of neurons?

They receive and transmit information through electrical and chemical signals.

What is the function of neuroglia?

They support, protect, nourish, and maintain neurons.

What are the major parts of a neuron?

The cell body, dendrites, and axon.

What is the function of dendrites?

They receive signals from other cells.

What is the function of the axon?

It carries nerve signals away from the cell body.

What are the three types of muscular tissue?

Skeletal muscle, cardiac muscle, and smooth muscle.