TissuesChapter 5

Objectives:1. List and describe the four major tissue

types, and provide examples of where each occurs in the body.

2. Name the types of epithelium, and identify an organ in which each is found.

3. Distinguish different types of connective and muscular tissues.

Tissue:

• Def.: a group of similar cells that performs a specialized function

• 4 major types of tissues:

A. Epithelial Tissues

• Forms linings throughout the body• Anchored to underlying connective tissue by a

nonliving layer called basement membrane1. Simple Squamous Epithelium - a single layer of

thin, flattened cells– Fit together tightly– Broad, thin nuclei– Substances pass through easily; easily damaged– Found in lung air sacs, capillary walls, and membranes

lining body cavities– ???

Epithelial Tissues (cont.)

2. Simple Cuboidal Epithelium – single layer of cube-shaped cells– Centrally located, spherical nuclei– Ovaries, kidney tubules, ducts of some glands– Adds in secretion and absorption

Epithelial Tissues (cont.)

3. Simple Columnar Epithelium – longer than they are wide (elongated, like columns)– Thicker– Nuclei located near the basement membrane– Ciliated – found in female reproductive tubes– Nonciliated – lining of uterus, stomach, intestines

Epithelial Tissues (cont.)

4. Pseudostratified Columnar Epithelium – appear to be stratified (layered), but are not– Why? Nuclei are found at different levels in the

cells, instead of only near the basement membrane.

– Many are ciliated.– Found lining respiratory passages

Epithelial Tissues (cont.)5. Stratified Squamous Epithelium– Many layers = thick (for protection) ???– Outer layer of skin (“epidermis”)– Lining of mouth, throat, vagina, and anal canal

6. Stratified Cuboidal Epithelium – 2-3 layers of cuboidal cells lining a lumen– Lines large ducts of glands (mammary, sweat, salivary,

pancreas) and of ovarian follicles and seminiferous tubules

7. Stratified Columnar Epithelium– Top layer elongated; base layer cube-shaped– Found in male urethra, vas deferens, and pharynx

???

Epithelial Tissues (cont.)

8. Transitional Epithelium – changes in response to tension– Found lining the bladder, ureters, and part of the

urethra– Contracted – thicker; many layers **– Relaxed – stretches and appears thinner

• See Table 5.3, p. 99!!

B. Connective Tissues• Made up of:– Cells, which are further apart than epithelial cells– Fibers– Matrix: intercellular material

• Major cell types:1. Fibroblasts – large, fixed, star-shaped cell that

secretes fibers2. Macrophages – wandering scavenger cells that

defend against infection3. Mast cells – large cells, located near blood

vessels, that secrete heparin and histamine

Fibroblast

http://www.cimaging.net/applications/examples/images/fibroblast3.jpg

http://images.google.com/imgres?imgurl=http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab5/IMAGES/MACROPHAGE%2520IN%2520SITU%2520copy.JPG&imgrefurl=http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab5/Lab5.htm&h=542&w=720&sz=508&hl=en&start=53&tbnid=djc9Xtw5JvKwoM:&tbnh=105&tbnw=140&prev=/images%3Fq%3Dmacrophage%26start%3D36%26gbv%3D2%26ndsp%3D18%26hl%3Den%26sa%3DN

Macrophage & Mast Cell

http://upload.wikimedia.org/wikipedia/commons/7/73/Macrophage_in_the_alveolus_Lung_-_TEM.jpg

http://www.healthsystem.virginia.edu/internet/hematology/images/Mast-cell-and-basophil-100x-website-arrow.jpg

http://www.bu.edu/histology/i/22602ooa.jpg

Connective Tissues (cont.)

• Connective tissue fibers:1. Strong, collagenous fiber (white fiber), made of

the protein collagen; adds strength2. Stretchy, elastic fiber (yellow fiber), made of

the protein elastin; adds ____________.3. Reticular fibers – thin collagenous fibers that

form supportive networks in tissue

Connective Tissues (cont.)1. Loose Connective Tissue (“areolar tissue”)– Cells are some distance apart; separated by gel-

like matrix– Forms delicate, thin membranes– Binds skin to underlying organs, fills space

between muscles

Connective Tissues (cont.)2. Adipose Tissue – fat– Large fat droplets in cells push nuclei close to the

cell membranes.– Beneath the skin, between muscles, around

kidneys, behind eyeballs, on heart, around joints

Connective Tissues (cont.)3. Dense Connective Tissue – closely packed,

thick collagenous fibers + elastic fibers– Strong!– Binds organs together– Found in tendons, ligaments, deep skin layers

Connective Tissues (cont.)4. Cartilage – a rigid connective tissue– Chondrocyte: cartilage cell– Perichondrium: around cartilage; membrane

surrounding cartilage; contains blood vessels to supply nutrients

– Three types of cartilage, distinguished by intercellular (???) matrix:

a) Hyaline cartilageb) Elastic cartilagec) Fibrocartilage

Connective Tissue (cont.)a) Hyaline cartilage– Very fine collagenous fibers in matrix– White glass appearance– Ends of bones in joints, soft part of nose

b) Elastic Cartilage– Dense network of elastic fibers = more flexible– Framework for external ears and parts of larynx

c) Fibrocartilage– Very tough; many collagenous fibers– Forms intervertebral discs and pads between

bones in knees and pelvic girdle

Insert Pics!!!Hyaline cartilage cells

Elastic cartilage cells

Fibrocartilage

http://cellbio.utmb.edu/microanatomy/bone/fcartilage.jpg

http://www.bartleby.com/107/Images/small/image295.jpg

Connective Tissue (cont.)

5. Bone – the most rigid connective tissue– Matrix made of mineral salts and collagen fibers– Osteocyte: bone cell

6. Blood

• See Table 5.4, p.105!!!

???

C. Muscle Tissues1. Skeletal muscle tissue (“voluntary”)– Long, threadlike cells– Striations: alternating light and dark cross-

markings– Each cell has many nuclei just beneath the cell

membrane.

Muscle Tissues (cont.)2. Smooth muscle tissue (“involuntary”)– No striations– Cells are shorter than skeletal muscle, spindle-

shaped, and have one, centrally located nucleus.– Line walls of internal organs

Muscle Tissues (cont.)3. Cardiac muscle tissue – heart– Striated and joined end-to-end– Each cell has only one nucleus. ???

D. Nervous Tissue

• Nervous tissue is– found in the brain, spinal cord, and nerves. – made up of:• Neurons: nerve cells• Neuroglial cells: helper cells

– “glia” = glue– Support and bind components of nervous tissue to each

other and to blood vessels

• See Table 5.5, p.107!!!