*A group of specialized cells with specialized functions Histology – the study of tissues

4 Major Tissue Types: Function – Location Epithelial : protects, secretes, senses, absorbs, excretes – covers body surfaces composes glands Connective : Binds, supports, protects, fills space, stores fat, produces blood cells – through out the body Muscle : allows movement – attached to bones, in the walls of hollow internal organs, heart Nervous : transmits impulses for coordination, regulation, integration, and sensory reception - brain, spinal cord, nerves

I. Epithelial Tissue Covers all body surfaces, lines most internal organs and are the major tissues of glands Always has a free surface Underside of tissue is always anchored to connective tissue by a thin non cellular layer called the basement membrane Lacks blood vessels and is replaced continuously Epithelial cells Basement membrane Connective tissue

Classification of epithelial tissues Cell Shapes 1.Squamous – thin, flat Good for exchange of gases, nutrients, waste products (lung and blood vessels) 2.Cuboidal – typically square or round Found lining the ducts of many glands 3.Columnar – tall and narrow Found lining the intestines Often have small projections on exposed surface (MICROVILLI) that increase surface area for absorption

Classification of epithelial tissues 1.Simple – have a single layer of cells 2.Stratified – Tissue contains a few to many layers of cells on top of each other Only bottom layer are bound to basement membrane Upper layers have cells bound to other cells 3.Pseudostratified columnar – all cells are bound to the basement membrane but not all cells reach the exposed surface. 4.Transitional – Specialized type of epithelia found in organs that stretch

Use your text and web site to describe the structure, function, and location of each type of epithelial tissue 1.Simple squamous epithelium 2.Simple cuboidal epithelium 3.Simple columnar epithelium 4.Pseudostratified columnar epithelium 5.Stratified squamous epithelium 6.Transitional epithelium 7.Glandular epithelium

1. Simple squamous epithelium

2. Simple cuboidal epithelium

3. Simple columnar epithelium

4. Pseudostratified columnar epithelium

5. Stratified Squamous Epithelium

6. Transitional Epithelium Distended

Epithelial tissue histology Simple Squamous: Single, layer of thin cells Simple cuboidal: Single layer of cube or round cells

Simple columnar: Single layer of tall cells, all cells reach the exposed surface, microvilli present Pseudostratified columnar: Single layer of columnar cells, nuclei are scattered, not all cells reach exposed surface Microvilli or Cilia

Keratinized, stratified squamous epithelia: Many layers of cells, lower cells are alive and dividing, upper cells are dead and filled with keratin, CANNOT SEE NUCLEI Non-keratinized stratified squamous epithelia : Many layers of cells, all alive, CAN SEE NUCLEI

Transitional epithelium: Cells are alive and overlapping, may appear single layer when tissue is stretched -Found in tissues that need to stretch on a regular basis -Have a cuboidal appearance in a relaxed tissue but “TRANSITION” to a squamous appearance when stretched Tissue Samples

7. Glandular Epithelium – found in glands and contain cells that function in secreting and producing substances. Exocrine gland – gland that secretes into ducts or onto a body surface (internal or external). Endocrine gland – gland that secretes hormones directly into the blood or body fluids *thyroid gland, pituitary and adrenal glands, islet cells of the pancreas Table 5-2 p133

Types of Exocrine glands 1.Merocrine gland – release fluids without a loss of cytoplasm *sweat glands, salivary glands

Types of Exocrine glands 2.Apocrine gland – lose small amts of their cell bodies during secretion *mammary glands; milk contains molecular components

Types of Exocrine glands 3.Holocrine gland – release entire cells with secretory products…”self destruct” *sebaceous, some sweat glands (pubic and breast)

II. Connective Tissues -A tissue that is abundant throughout the body, it includes bone, cartilage, and various fibrous tissues. Function : bind, support, fill spaces, store fat, produce blood cells, and helps repair damaged tissue

Characteristics of Connective Tissue: -Most are well vascularized -Extracellular matrix (liquid, solid, or semisolid) exp: Adipose is mostly cellular vs bone is mostly matrix - 2 cell types -3 types of fibers

2. Wandering Cells - present in tissues usually in response to injury and infection; includes white blood cells a) macrophage - carry out phagocytosis, function in the defense of foreign bodies from tissues 2 Cell types 1. Resident Cells - present in stable #’s a) fibroblasts - lg star shaped cell that secretes protein to produce fibers b) mast cells - lg cells found near blood vessel, they release heparin and histamine

3 Types of Connective Tissue Fibers 1. Collagenous - thick, strong, threadlike white fibers that are composed of collagen. *tendons 2. Elastic - yellow, elastic fibers that are common in parts that are often stretched. *vocal cords 3. Reticular - thin, fine fibers composed of collagen *various tissues (lymph nodes, bone marrow, spleen)

Types of Connective Tissue -defined by fiber type and number of fibers in the matrix 1. Bone : provides structure, support, protection and serves as attachment, it also functions in forming blood cells contains mineral salts and collagen fibers

Also called the osteonic / central canals The lamellae forms the layers of the matrix (rings)

2. Cartilage : rigid and flexible, provides support, framework for attachment, protects and forms structure for developing bones Chondrocyte - cartilage cell lacks blood vessels but is surrounded by them, relies on diffusion to obtain nutrients (heals slowly) * most cartilage cells occupy a small chamber called lacunae Types of Connective Tissue

Types of Cartilage p Fig 5-21 – Fig 5-23 A. Hyaline - moderate amts of collagen in matrix giving a shiny/glass like appearance. Most prevalent. *end of nose, ribs, ends of bones, fetal skeleton B. Elastic - flexible, contains elastic fibers, highly flexible *framework of ear and larynx C. Fibrocartilage - tough, densely packed collagen fibers, provide shock absorption *intervertebral disks, cushions bones in the knee

Hyaline cartilage Elastic cartilage Fibrocartilage

Types of Connective Tissue 3. Fibrous - dense, tightly packed collagenous fibers with few cells and fibroblasts Functions in binding body parts together and found in tendons and ligaments or skin, outer walls of kidneys and spleen P139 Fig 5-17, and 5-18 Dense fibrous regular & Dense fibrous irregular

Types of Connective Tissue 4. Loose / Areolar - mainly composed of fibroblasts this tissue forms the thin membrane between organs. Gel/fluid matrix with multiple types of fibers and cells. It can be found beneath the skin and between muscles.

Types of Connective Tissue 5. Adipose - a form of loose connective tissue that stores fat in its cell cytoplasm * found beneath skin, beneath muscles, around the kidneys, behind the eyeballs, in some abdominal membranes, around certain joints and on the surface of the heart.

Types of Connective Tissue 6. Reticular - phagocytic: ingest and destroy foreign particles. Defend the body against infection or invasion (macrophages). *Found in lymphatic organs - lymph nodes, spleen, blood, and bone marrow

Other Types of Connective Tissue 7. Blood - transports substances, maintains homeostasis Fluid matrix - Blood Plasma a) red blood cells (erthrocytes) b) white blood cells (leukocytes) c) platelets - cellular fragments (thrombocytes) *blood cells are formed in the hollow parts of certain bones Hematopoietic tissue also called red bone marrow.

III. Muscle Tissue - contractile tissue that moves parts that are attached to it. 3 Different Types 1. Skeletal - found in muscles and usually attached to bones that can be controlled by a conscious effort (voluntary muscle tissue). Cells are long and thread like with striations and have more than 1 nuclei per cell.

2. Smooth - lacks striations, found in the walls of hollow internal organs (stomach, bladder, uterus, blood vessels). Usually controlled by involuntary muscle tissue, uninucleate.

3. Cardiac - found only in the heart. Its cells are striated and each cell has a single nucleus. Its cells are joined by intercalculated disks (controlled involuntarily)

IV. Nervous Tissue - makes up the brain, spinal cord and peripheral nerves neurons - nerve cells that are sensitive to changes in their surroundings and respond by sending impulses to other neurons or to muscles or glands. Function: coordinate, communicate and regulate body function neuroglial cells - support, connect, insulate and protect nervous tissue, but do not conduct like neurons.

Neuroglial cells Nerve cell

Some things to look at before the test: *Read over Box 5-1 – 5-4. Emphasis on the terminology used in Box 5-3!!!!! *Hint – you might see some of those bold faced words again! *Know difference between parietal membranes and visceral membranes Fig 5-32 on p148 helps in identifying.