1. Lecture and Lab exercise 5 Tissues
Part I

2. Question
What is a tissue?

3. Tissues
A tissue is composed of specialized cells of the same type that perform a common function in the body.

4. Question
What are the four major tissue types found in the human body?

5. Types of Tissues
The tissues of the human body can be categorized into four major types.
Epithelial Tissue
Connective Tissue
Muscular Tissue
Nervous Tissue

6. Question
What is the function of the Epithelial Tissue?

7. Function of Epithelial Tissues
cover body surfaces and lines body cavities.
protects, absorbs molecules, absorbs nutrients, and removes impurities out of the body.
are described as avascular.

8. Epithelial cells
Epithelial cells must create a layer that prevents leakage from one side of the sheet to the other because they cover the surface of organs and line the body cavities.

9. Question
What is the function of the basement membrane? What is the basement membrane composed of?

10. Basement membrane
The basement membrane is composed of carbohydrates and proteins that anchors the epithelium to underlying connective tissue.

11. Epithelium
Basement membrane
Connective Tissue

12. Question
How are epithelial tissues classified?

13. Epithelial tissues are classified according to
Cell shapes.  Epithelial cells vary in shape depending on their function.
Arrangement of cells in layers.  The cells are arranged in one or more layers depending on function

15. Question
What are the basic types of epithelia?

16. Types of Epithelial Simple squamous Simple cuboidal Simple columnar
Pseudostratified ciliated columnar
Stratified squamous
Transitional epithelium
Glandular epithelia

17. Simple epithelium
Simple epithelium is a single layer of cells that functions in diffusion, osmosis, filtration, secretion, or absorption. Secretion is the production and release of substances such as mucus, sweat, or enzymes. Absorption is the intake of substances, such as digested food from the intestinal tract.

18. Stratified epithelium
Stratified epithelium (stratum = layer) consists of two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear

19. Pseudostratified epithelium
Pseudostratified epithelium (soo′-dō-STRA-te-fīd; pseudo- = false) appears to have multiple layers of cells because the cell nuclei lie at different levels and not all cells reach the surface, but it is actually a simple epithelium because all its cells rest on the basement membrane.
Cells that do extend to the surface may contain cilia; others (goblet cells) secrete mucus.

20. Squamous cells
Squamous cells (SKWĀ-mus = flat) are thin, which allows substances to pass rapidly through them.

22. Keratinized and Nonkeratinized Stratified Squamous Epithelium

24. Cuboidal Cells are as tall as they are wide and are shaped like cubes.
They may have microvilli at their apical surface and function in either secretion or absorption

26. Columnar cells
Columnar cells are much taller than they are wide and protect underlying tissues.
Their apical surface may have cilia or microvilli, and they often are specialized for secretion and absorption.

27. Question What is the function of cilia?
What is the function of microvilli?
Where are these structures found in your body?

28. Cilia Is involved in movement.
The ciliated cells that line our respiratory tract sweep debris trapped within mucus back up the throat. This helps keep the lungs clean.
Ciliated cells found in the oviduct move an egg along the oviduct toward the uterus.

29. Microvilli Are found in the small intestine
Increase the surface area for the absorption of nutrients.

30. Simple columnar Epithelial
Nonciliated simple columnar
Ciliated simple columnar

33. Transitional cells
Transitional cells change shape; they “transition” between squamous and cuboidal, allowing organs such as the urinary bladder to stretch to a larger size and then collapse to a smaller size

35. Question
What type of epithelial tissue is found in the walls of the urinary bladder to provide it with the ability to distend?

36. Glandular Epithelial Tissues
Glandular epithelia secrets a product wither into ducts or into the blood.
Glands
Exocrine glands
Secrete into ducts to exterior of body
Salivary glands, mammary glands and sweat glands
Endocrine glands
Secrete into the blood to carry chemical messages throughout the body
Thyroid gland, and parathyroid gland

37. Exocrine glands secrete fluids into ducts

38. Endocrine cells secrete hormones into the blood

39. Cell Junctions
The epithelial cells of a tissue are connected by cell junctions.
These junctions help a tissue perform its particular function.

40. Cell junctions Junctions: hold epithelial cells together
Tight junctions
Allow epithelia cells to form a layer that prevents leakage from one side of the sheet to the other
Adhesion junctions/spot desmosomes
Keep cells anchored to one another, but the layer of cells can still bend and stretch.
Gap junctions
Allow the passage of small molecules and ions from one cell to the other.

41. Tight junction proteins
Protein filaments
Protein channel
Intercellular space
Intercellular space
Intercellular space
a) Tight junctions form
leak-proof seals
between cells.
b) Adhesion junctions
anchor two cells together,
yet allow flexibility of
movement.
c) Gap junctions provide
for the direct transfer of
water and ions between
adjacent cells.
Figure 4.2

42. Questions
What are the three types of junctions between cells, and how do they differ in structure and function?
Why would you expect cell junctions more often in epithelia than in other types of tissues?
Which type of cell junction would you expect to find between muscle cells in the heart wall? Why?

43. Activity 1.
complete Box 5.1 Organs, Tissues, and Functions

44. Box 5.1 Organs, Tissues, and Functions
Function of Tissue
Heart
Kidney
Eye
Lung
Stomach
Esophagus

45. Activity 1 Examine the following photomicrographs and describe them.
Also include their function and location.

46. .

47. Simple squamous epithelium

48. Stratified squamous epithelium

49. Simple Cuboidal Epithelium

50. Simple Columnar Epithelium

51. Pseudostratified Ciliated Columnar Epithelium