Anatomy and Physiology I Tissue Types

Key Terms Histology: the study of tissues. Tissues: groups of cells which are similar in structure and which perform common or related functions.

Four Basic Kinds of Tissues Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue

Epithelial Tissue Epithelial Tissue Locations: Covers the body Lines the cavities, tubes, ducts and blood vessels inside the body Covers the organs inside body cavities Epithelial Tissue Functions: Protection from physical & chemical injury, Protection against microbial invasion, Contains receptors which respond to stimuli, Filters, secretes & reabsorbs materials and Secretes serous fluids to lubricate structures.

Examples of Epithelium Tissue Lines the respiratory tract Lines the digestive system Skin Surrounding internal organs Characteristics of Epithelium Tissue Cells are tightly packed Regenerate easily Avascular – lack blood vessels apical surface – exposed surface Basement membrane – anchors down cells

Connective Tissue Connective Tissue: Connective Tissue Functions: Most abundant & widely distributed tissue Connective Tissue Functions: Connects, binds and supports structures, Tendons, ligaments, etc. Protects & cushions organs and tissues, Insulates (fat) and Transports substances (blood).

Examples of Connective Tissue Bones Cartilage Tendons Blood Fat Characteristics of Connective Tissue Most are well vascularized – have a good blood supply Some have very poor blood supply being avascular. Extracellular matrix – nonliving substance found outside the cells

Extracellular Matrix explained Nonliving material between cells Produced by the cells and then extruded Responsible for the strength Two components Ground substance Of fluid, adhesion proteins, proteoglycans Liquid, semisolid, gel-like or very hard Fibers: collagen, elastic or reticular

Epithelial Tissue in Detail

Classification of epithelia According to thickness “simple” - one cell layer “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical(base) layer) According to shape “squamous” – wider than tall “cuboidal” – as tall as wide “columnar” - taller than wide

Classes of Epithelia Simple: just one layer or cell shape Stratified: multiple layers and cell shapes Human Anatomy, Larry M. Frolich, Ph.D.

Human Anatomy, Larry M. Frolich, Ph.D. Simple Epithelia Human Anatomy, Larry M. Frolich, Ph.D.

to protect

where diffusion is important where tissues are involved in secretion and absorption: larger cells because of the machinery of production, packaging, and energy requirements

Simple Squamous Epithelium Descriptions: Single layer, flattened cells, simplest of epithelia Function: Allows passage of materials by diffusion and filtration Secretes lubricating substances Location: Air sacs of lungs, lining of heart, blood vessels, lining of ventral body cavity

Simple Cuboidal epithelium Descriptions: Single layered, cube like, large spherical central nuclei Function: Secretion and absorption Location: Kidney tubules, ovary surfaces

“ciliated” literally = eyelashes (see next page)

Simple Columnar Epithelium Descriptions: Single layer, tall, round or oval nuclei, some bear cilia, may contain mucus-secreting glands(goblet cells) Function: Absorption, secretion of mucus and enzymes, cilia propels mucus Location: Nonciliated lines the digestive tract Ciliated lines small bronchi, uterine tubes, parts of uterus.

Pseudostratified Columnar Epithelium Descriptions: Single layer w/ differing heights, nuclei at different levels, may have goblet cells or cilia Function: Secretion(especially mucus), propulsion of mucus by ciliary action Location: Nonciliated in sperm carrying ducts Ciliated lines the trachea and upper respiratory tract.

Stratified: regenerate from below

Stratified Squamous Epithelium Descriptions: (most common stratified) Several layers, surface cells are squamous, basal cells are cuboidal or columnar Function: Protects underlying tissues in areas of abrasion Location: Esophagus, the mouth, outer portion of skin

Rare…

Stratified Cuboidal Epithelium Descriptions: (rare) Usually two layers of cube-like cells Function: Protection Location: Rare Largest ducts of sweat glands, mammary glands, and salivary glands.

Rare…

Stratified Columnar Epithelium Descriptions: (rare) Several layers thick, columnar with varying in size and shape Function: Protection, secretion Location: Rare Large ducts of glands

Transitional Epithelium Descriptions: Highly modified, several layers of cuboidal or columnar cells Function: Stretches readily, allowing distention of urinary organs Location: Lines the ureters, bladder, parts of urethra

Human Anatomy, Larry M. Frolich, Ph.D.

Can You Identify the Classes of Epithelium? Quiz!! E Can You Identify the Classes of Epithelium? D A B C Human Anatomy, Larry M. Frolich, Ph.D.

Specific Connective Tissue In Detail

Bone Descriptions: Aka: osseous tissue Function: Location: Hard calcified matrix, surrounded by layers of calcium salts in additions to lots of collagen fibers Cells sit in cavities called “lacunae” Function: Protection and support Location: Skeletal system

Hyaline Cartilage Descriptions: (hyalin=glass) Function: Location: Most common and widespread type Collagen fibers with a rubbery matrix Function: Supports/reinforces, resilient cushioning Location: Covers ends of bones in joints, nose, trachea, larynx, embryonic skeleton

Elastic Cartilage Descriptions: Function: Location: Collagen fibers with a rubbery matrix Very elastic Function: Maintains shape of structure gives flexibility Location: External ear epiglottis

Fibrocartilage Descriptions: Function: Location: Similar to hyaline but less firm Much like a cushion Function: Absorbs compressive shock Location: Intervertebral discs, discs of knee joint

Dense Connective Tissue Descriptions: Collagen fibers, fibroblasts fill gaps between collagen Strong ropelike structures like tendons and ligaments Function: Connect muscles to bones, connect bones at joints, lots of tensile strength Location: joints

Vocab Fibroblasts – cells that make collagen fibers Tendons – attach skeletal muscles to bones Ligaments - connect bones to bones at joints. More stretchy and contain more elastic fibers than tendon

Loose CT: Areolar Tissue Descriptions: Gel-like matrix w/ all three fiber types Very loose network w/ lots of open space Function: Wraps and cushions organs, a reservoir of water and salts for surrounding tissues, important for swelling Location: Under epithelia, around organs, surrounds capillaries

Loose CT: Adipose Tissue Descriptions: (fat) Very similar to areolar tissue Fat cells predominate Function: Insulates against heat loss, supports and protects organs, reserve food fuel Location: Under skin, around kidneys and eyeballs, abdomen and breast

Loose CT: Reticular CT Descriptions: Function: Location: Network of reticular fibers (similar to fibroblast) Delicate network of interwoven fibers Function: Form soft internal skeleton that supports other cells such as white blood cells, mast cells Location: Lymphoid organs (lymph nodes, bone marrow, spleen)

Blood Descriptions: (vascular tissue) Function: Location: Red and white blood cells in a fluid matrix (plasma) Fibers are soluble only seen during clotting Function: Transportation of gases, nutrients, wastes ect. Location: Everywhere

Muscle Tissue Muscle Tissue: Muscle Tissue Functions: Associated with the bones of the skeleton, the heart and in the walls of the hollow organs of the body. Made to contract Called muscle fibers because they are elongated to provide a long axis for contraction Muscle Tissue Functions: Movement Maintains posture Produces heat Facial expressions Pumps blood Peristalsis

Specific Muscle Tissue Types: skeletal muscle Cardiac muscle Smooth muscle

Skeletal Muscle Descriptions: Function: Location: Long, cylindrical, obvious striations, multinucleated Function: Voluntary movement, manipulation of the environment, facial expression Gross body movement Location: Attached to bones

Cardiac Muscle Descriptions: Function: Location: Branching, striated, uninucleated cells that fit tightly together at junctions called “intercalated disks” Function: Involuntary control, propels blood into circulation. Location: Walls of the heart

Smooth Muscle Descriptions: (visceral) Function: Location: No striations, spindle-shaped w/ central nuclei Arranged closely to form sheets Function: Propelles substances along internal passageways, involuntary control Peristalsis – wavelike motion Location: Walls of the stomach, bladder, uterus and blood vessels

Nervous Tissue Nervous Tissue: Nervous Tissue Functions: Main component of the nervous system, ie., brain, spinal cord & nerves. Nervous Tissue Functions: Regulates & controls body functions Generates & transmits nerve impulses Supports, insulates and protects impulse generating neurons.

Nervous Tissue Descriptions: (Neurons) Function: Location: Branching cells, has long extended parts Irritability and conductivity Have “supporting cells” that insulate, support and protect neurons. Function: Transmits electrical signals from sensory receptors to effectors that control their activity Location: Brain, Spinal cord and nerves

Muscle - Skeletal Muscle fibers (cells) long, parallel & cylindrical With many nuclei (multinucleate) Striations (cross stripes run perpendicular to the cells Produce voluntary movement Locomotion Heat

Specific Nervous Tissue Types Nervous – Neuron Branching cells with many long processes Large central nucleus Transmit impulses from one area of the body to other areas Regulate activities through neuron impulses