TISSUES OF THE BODY Body Tissues

Key Terms Histology: the study of tissues. Tissues: 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 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.

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

Muscle Tissue Muscle Tissue location: Associated with the bones of the skeleton, the heart and in the walls of the hollow organs of the body. Functions: Movement Locomotion Maintains posture Produces heat Facial expressions Pumps blood Peristalsis( wave- like motion )

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

Different types of Epithelium

Squamous Epithelium Simple – one cell thick Stratified – multiple layers Stratified – multiple layers Forms epidermis Forms epidermis

Cuboidal Epithelium Simple – one cell thick Roughly cube shaped Duct Cuboid Cells Duct Cuboid Cells

Columnar Epithelium Simple – one cell thick Column shaped (long & narrow) Pseudostratified – gives the appearance of more than one layer of columnar epithelial cells

THE CONNECTIVE TISSUES consist of a population of cells surrounded by fibers and aground substance. These tissues connect and anchor structures and give support to the body and its organs. 1. Loose connective tissues (adipose tissue) 2. Dense connective tissues (tendon) 3. Support tissue (cartilage and bone) 4. Blood and blood forming tissue (red marrow)

Loose Connective - Adipose Stores energy (fat) Stores energy (fat) Insulates Insulates Supports & protects organs Supports & protects organs

Dense Connective- Tendon In tendon and ligament, fibers are thick, long and grouped in parallel assembly for tensile strength.

Support tissue - Bone Supports & protects Supports & protects Mineral storage Mineral storage Fat storage Fat storage Blood cell production Blood cell production

Support tissue – Hyaline Cartilage Supports while providing flexibility Supports while providing flexibility Absorbs compression between bones in joints (articular cartilage) Absorbs compression between bones in joints (articular cartilage) Holds open respiratory passages Holds open respiratory passages Most abundant type of cartilage in body Most abundant type of cartilage in body

Blood Blood is considered a connective tissue because it has a matrix. The fluid portion of whole blood, its matrix, is called plasma.

Muscle Tissue Types: Consists of specialized cells that contract when stimulated The body has three types of muscle tissue: Skeletal (voluntary) Cardiac (involuntary) Smooth muscle (involuntary)

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

Cardiac Muscle Cells, found only in the heart, are striated and branching (with one nucleus); They are joined by intercalacted discs which allow the cells to synchronize the beating of the heart.

Smooth Muscle Lack of visible cross striations (hence the name smooth). Nucleated Is responsible for the contractility of hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, or the uterus.

Specific Nervous Tissue Types Nervous – Neuron Conducting cells, called neurons, transmit impulses from one region of the body to another.

Membranes Sheets of tissue that cover or line surfaces or that separate organs, or parts of organs from one another. Mucous – line cavities or passages -that open to the exterior such as mouth, esophagus, digestive tract, respiratory passages Function in protection, secretion of mucus, and absorption Cutaneous Membrane- Covers the body Are continuous with mucous membranes(skin)

Serous membrane Line closed cavities of the body such as thoracic, abdominal, and sac in which heart lies. Also cover organs lying in those closed cavities Has two layers Visceral – covers organs Parietal – lines the cavity Space between the two layers is kept moist by the secretion of serous fluid.

Synovial Membranes- Line joints, tendons, and bursa(A sac containing synovial fluid at sites of friction) Secrete synovial fluid which prevents friction on the smooth, moist surfaces