1. Chapter 5 – Tissues (Histology)
Body tissues are divided into 4 categories:
Connective
Nerve
Muscle
Epithelial

2. 1. Connective Tissue
-Functions: Connect, support, transportation (blood), defense, and storage (fat)
-cells are surrounded by some type of non-living matrix
-classified by their structure and the type of matrix
-there are four major classes of connective tissue with subcategories

3. I. Fibrous, II. Bone, III. Cartilage, IV. Blood

4. I. Fibrous (have extracellular fibers)
Loose- the stretchable fascia between organs- like an elastic glue spread between organs

5. Adipose- fat storage under the skin
-important for protection and insulation

6. reticular- web like fibers of the lymphatic (immune) system
- helps filter blood
- contains white blood cells to destroy dangerous invaders

7. dense- tendons and ligaments –flexible but strong
-tendon- connects muscle to bone
-ligament- connects bone to bone

8. II. Bone bone cells are called osteocytes
-osteoblast- bone building cell
-osteoclast-­­ bone destroying cell
the 2 cells above work together and can reshape bone
a “unit” of bone is known as the Haversian System (see fig 5-20)
the cells are squeezed between the hard matrix of mineral salts (mostly calcium)
flat bones are called membranous bones (skull, pelvis)

9. Osteocytes
Haversian system
Cross-section of long bone

10. III. Cartilage chondrocytes are cartilage producing cells
cartilage is avascular (no blood vessels)
there are 3 subcategories of cartilage

11. hyaline cartilage- shiny and smooth, at the ends of bones (linings of joints)
chondrocytes

12. Fibrocartilage- strongest and most durable, “shock absorbers” (intervertebral discs, meniscus of the knee joint)

13. Elastic cartilage- most flexible cartilage
(ears, nose, larynx)

14. IV. Blood
Considered a connective tissue because it is made in the bones
Hematopoiesis- the process of blood production in the red marrow of the bones
has a liquid matrix called plasma
There are 3 main types of blood cells:
Erythrocytes- red blood cells: carry O2 (some CO2)
Leukocytes- white cells: kill invaders
Thrombocytes- responsible for blood clotting by producing platelets

16. 2. Muscle Tissues All are responsible for movement
-May be voluntary or involuntary
-May be striated or non-striated

17. Voluntary= may be “willed” to move
Involuntary= not controlled by thought or will
Striated= visible “stripes” on tissue
Non-striated= no visible “stripes

18. I. Skeletal muscle Striated and voluntary
Cells are very long and thin with multiple nuclei

19. II. Smooth Muscle Non-striated and involuntary
Cells are shorter and each with one nucleus

20. III. Cardiac muscle (heart)
Striated and involuntary
Cells connect at dark “disks” and only one nucleus per cell.

21. 3. Nerve Tissue -Rapidly regulate and integrate body activities
-2 basic kinds of cells
1. neurons=conducting cells
2. glial cells= support cells

22. Important parts of a neuron:
Soma: main body of cell (nucleus is here)
Dendrites: short thin branches that carry signal towards the soma
Axon: long thin “wire” carrying signal away from the soma
Synapse: where neurons connect to transmit signal

23. One Very Important Glial Cell:
Schwann Cells- wrap around the axon to insulate the “wiring” to speed nerve signal transmision
- Responsible for the fatty white matter of the nervous system

24. 4. Epithelial Tissue
-Cells are tightly packed into sheets with no “matrix” between cells
-sheets of cells attached to a “basement membrane”
-cells are attached to each other by “tight junction” making a tight seal
- one side is “exposed” to either internal or external environment
-2 main types:
membranous
glandular

25. Membranous Epithelium
Classification is based on shapes and layers:

26. Description of Cell Shapes: Squamous -(flat and scaly) Cuboidal -(cubic) Columnar -(tall narrow column) Pseudostratified columnar -(odd columns, not all reach the surface)

27. Description of Layers: Simple (one layer) Stratified (several layer of same cell type) Transitional (many layers transitioning to different cell types)

28. Simple Squamous - VERY thin. Where quick diffusion is necessary
lining of blood vessels, tiny air sacs in lungs, parts of kidney, etc.
“flat”
Cross-section

29. Stratified Squamous - areas that receive friction
skin, mouth, esophagus
Cross-section

30. Cuboidal
- lines many ducts and tubules
Cross-section

31. Columnar epithelium - may be ciliated with tiny “hairs” (cilia)
Non ciliated
- lines gastrointestinal tract
Ciliated
- lines respiratory tract

32. Transitional
- bladder – allows for expansion
Cross-section

33. Glandular Epithelium Synthesizes and secretes a chemical product
Endocrine gland- secrete directly to bloodstream
Exocrine gland- secrete into collecting ducts
Unicellular gland- single cells called goblet cells that produce mucous

34. Pituitary: Example of an endocrine gland

35. Exocrine glands come in a wide variety of shapes:

36. Exocrine Secretion:
Merocrine- hormones released through cell membrane (sweat & salivary glands, mucous producing goblet cells)
Apocrine- part of cell containing hormones pinches off (mammary gland)
Holocrine- cell bursts to secrete products and must be replaced (sebaceous gland)