*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

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 epithelium7. 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

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)

http://faculty.une.edu/com/abell/histo/histolab2.htm

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; includeswhite blood cells

a) macrophage - carry out phagocytosis, functionin 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 proteinto produce fibers

b) mast cells - lg cells found near blood vessel, theyrelease heparin and histamine

http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_frame4.html

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 / centralcanals

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 p140-141 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 cartilageFibrocartilage

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 kidneysand spleen

P139 Fig 5-17, and 5-18Dense fibrous regular &Dense fibrous irregular

Types of Connective Tissue

4. Loose / Areolar - mainly composed of fibroblaststhis 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 ofthe heart.

Types of Connective Tissue

6. Reticular - phagocytic: ingest and destroy foreign particles. Defend the body against infectionor 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 Plasmaa) red blood cells (erthrocytes)b) white blood cells (leukocytes)c) platelets - cellular fragments (thrombocytes)

*blood cells are formed in the hollow parts of certain bonesHematopoietic 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 striationsand 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 striatedand each cell has a single nucleus. Its cells are joined by intercalculated disks (controlledinvoluntarily)

http://www.histology-world.com/videos/video.htm

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 terminologyused in Box 5-3!!!!!

*Hint – you might see some of those bold faced words again!

*Know difference between parietal membranes and visceralmembranes Fig 5-32 on p148 helps in identifying.