TISSUES

1. TISSUES

2. Cells Tissues Organs Organ systems Organism Cells are not found by themselves; they’re with others. These are called tissues. TISSUE: A group of cells, usually similar, which share a particular function. ORGAN A group of tissues which share a particular function. ORGAN SYSTEM: A group of organs which share a particular function (digestive system, nervous system).

3. Cell Differentiation • Through the process of cell differentiation, each cell develops a characteristic set of structural features. • Each cell has to contribute one piece toward the overall function of the organism, so that all the vital functions can be covered. • During differentiation, cells in nearby locations become able to work together. • After differentiation, cells do not change their function throughout their life cycle

4. TYPES OF TISSUES WE’LL DISCUSS: • EPITHELIUM: a sheet of cells that makes up the surface of the skin and also lines tubes in the body. • CONNECTIVE TISSUE: deep to the epithelium; supplies oxygen and nutrients to epithelium. • Fibrous (Proper) Connective Tissue • Special Connective Tissue (cartilage, bone, blood, muscles, nerves) • MUSCLE TISSUE: makes up muscles, and these cells are able to contract, unlike fibrous connective tissue. It is bound together by areolar connective tissue. (discussed in later lectures) • NERVOUS TISSUE: makes up brain and nerves (discussed in later lectures)

5. EPITHELIA: (plural form of epithelium): a sheet of cells that makes up the surface of the skin and also lines tubes in the body. Function of epithelia: • The epithelial cells are the type of tissue that protects the underlying structures • What is the difference between epithelium and epidermis? • Epidermis is the outermost layer of skin. It consists of epithelial cells, but epithelium is also found in areas lining the tubes of the body (digestive, respiratory, urinary systems, etc)

6. Epithelium • Epithelium is the tissue that covers the outside of the body (the top layer of the skin), and it also lines the tubes within the body. • Digestive tract • Respiratory tract • Cardiovascular system • Urinary tract • Reproductive tract • Sweat glands and other exocrine glands

7. Microvilli • The presence of large numbers of microvilli on the exposed surfaces of epithelial cells indicates that this is the area where absorption and secretion take place. • These cells are transportation specialists. • They are probably located along portions of the digestive and urinary tracts

8. Kidney • The hollow space within each of these tubes is called a lumen. • The lumens are always lined by epithelial cells. Sweat glands Trachea

9. Basement Membrane • All epithelia sit on top of connective tissue, and is connected to it by a BASEMENT MEMBRANE (which is not a cell membrane), made of protein fibers that connect to epithelium. • The only function of the basement membrane is to attach the epithelium to the connective tissue beneath it. • Epithelia get oxygen and nutrients from the blood vessels in the connective tissue beneath the basement membrane.

10. Special Characteristics of Epithelia Figure 4.1

11. Epithelium • Epithelium is always BIPOLAR: • APICAL SIDE: touches the lumen (inside heart, stomach, etc). • BASAL SIDE: touches the basement membrane

12. Classifications of Epithelia Figure 4.2

13. SIMPLE EPITHELIUM • SIMPLE EPITHELIUM has only one cell layer. • SIMPLE SQUAMOUS EPITHELIUM: • SIMPLE CUBOIDAL EPITHELIUM • SIMPLE COLUMNAR EPITHELIUM • PSEUDOSTRATIFIED EPITHELIUM

14. SIMPLE SQUAMOUS (thin) EPITHELIUM • SIMPLE SQUAMOUS (thin) EPITHELIUM are flat cells that allow diffusion of materials between the cells. • This type of epithelium is in regions where a lot of diffusion is needed from one compartment to another, such as the lungs and a region in the kidney called the glomerulus.

15. Simple Squamous Epithelium Found in the lungs Figure 4.3a

16. Simple Squamous Epithelium Found in the kidneys (glomerulus) Found in the lungs

17. SIMPLE CUBOIDAL EPITHELIUM • SIMPLE CUBOIDAL EPITHELIUM is cube shaped and is also found in areas where there is a lot of material going across from one compartment to another. • This cell type has plenty of room for organelles. • This epithelium is found in the intestines, and a region of the KIDNEY called the convoluted tubules, and places that need diffusion as well as room for cell organelles.

18. Simple Cuboidal Epithelium Found in the kidneys (convoluted tubules) Figure 4.3b

19. Tubule Glomerulus KIDNEY Tubules are simple cuboidal Glomerulus is simple squamous

20. SIMPLE COLUMNAR EPITHELIUM • SIMPLE COLUMNAR EPITHELIUM is shaped like a column and are found in areas where the cells are needed for secretion and absorption (intestines). • When they are differentiated into GOBLET CELLS, they produce mucus.

21. Simple Columnar Epithelium Figure 4.3c

22. PSEUDO-STRATIFIED COLUMNAR EPITHELIUM • PSEUDO-STRATIFIED COLUMNAR EPITHELIUM is a single layer of cells that appears to be more than one layer thick, but it is not. The nucleus on one cell is at the top, and the nucleus of the next cell is at the bottom. • Pseudostratified epithelium always has cilia on its apical surface. Each cilium is a hair-like structure that moves back and forth to move material in a certain direction. • This type of epithelium needs goblet cells nearby to produce the mucus that contains the material to be swept. These cells will be found in the respiratory tract (the trachea), where the mucous catches the debris you inhale and the cilia sweeps the material up to your throat where you cough and swallow it. • Its only functions are protection and mucous production.

23. Pseudostratified Columnar Epithelium Found in the trachea Figure 4.3d

24. A Cilium Figure 4.8

25. STRATIFIED EPITHELIUM • STRATIFIED EPITHELIUM has more than one cell layer. The type of epithelium is named by the APICAL layer. • STRATIFIED SQUAMOUS EPITHELIUM: 1) Keratinized stratified squamous epithelium 2) Non-keratinized stratified squamous epithelium • STRATIFIED CUBOIDAL EPITHELIUM • STRATIFIED COLUMNAR EPITHELIUM • TRANSITIONAL EPITHELIUM

26. STRATIFIED SQUAMOUS EPITHELIUM STRATIFIED SQUAMOUS EPITHELIUM: the type is named by the apical cells. Stratified squamous epithelium is found in regions of the body where there is a lot of abrasions or wear-and tear, and it is the most protective (it is the thickest). • 1) KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM has apical cells that contain a protein called keratin, which is waterproof. All of our dry skin is this type, and it is especially thick in the palms and soles. It is very good at resisting abrasions. • 2) NON-KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM does not have the keratin, so it will be moist skin, like what is found lining the mouth and esophagus.

27. Stratified Squamous Epithelium (keratinized) Found in dry skin

28. Stratified Squamous Epithelium (non-keratinized) Found in moist skin (mouth and esophagus) Figure 4.3e

29. STRATIFIED CUBOIDAL EPITHELIUM • STRATIFIED CUBOIDAL EPITHELIUM usually consists of only two layers, and there is almost no diffusion between them. • It is found in sweat glands.

30. Stratified Cuboidal Epithelium Found in sweat glands Figure 4.3f

31. Stratified Cuboidal Epithelium Found in Sweat Glands

32. STRATIFIED COLUMNAR EPITHELIUM • STRATIFIED COLUMNAR EPITHELIUM usually has just a few layers and this type of epithelium inhibits diffusion of materials. • It is relatively rare, providing protection along portions of the pharynx, urethra, and anus.

33. Stratified Columnar Epithelium Figure 4.3g

34. TRANSITIONAL EPITHELIUM • TRANSITIONAL EPITHELIUM can stretch and change shape. • This type is what lines the urinary bladder and it looks like this as it goes from empty to full.

35. Transitional Epithelium Found in the urinary bladder Figure 4.3h

36. Connective Tissues Types of Connective Tissues • FIBROUS (PROPER) Connective tissues • SPECIAL CONNECTIVE TISSUE • Functions of Connective Tissues • Defend the body from invasion by microorganisms • Provide protection for delicate organs • Establish a structural framework for the body

37. FIBROUS (PROPER) Connective tissues • FIBROUS (PROPER) Connective tissues • ADIPOSE (fat) • RETICULAR (lymph nodes) • LOOSE (aka AREOLAR; upper dermis) • DENSE • REGULAR (tendons and ligaments) • IRREGULAR (lower dermis and joint capsules)

38. Adipose ADIPOSE Main cell type isanadipocyte (stores fat) Functions: • Cushions organs • Food Storage • Insulation

39. Adipose Tissue Figure 4.12c

40. Lipoma • These are benign fat nodules in the hypodermis, usually associated with high cholesterol levels. They are easily surgically excised (removed)

41. Liposarcoma • Patients usually note a deep seated mass in their soft tissue. Only when the tumor is very large do symptoms of pain or functional disturbances occur. Most frequent in middle-aged and older adults (age 40 and above), liposarcomas are the second most common of all soft-tissue sarcomas . Annually 2.5 cases occur per million population. The prognosis varies depending on the site of origin, the type of cancer cell, the tumor size, the depth, and proximity to lymph nodes. Well-differentiated liposarcomas treated with surgery and radiation have a low recurrence rate (about 10%) and rarely metastasize.

42. Why you got fat • http://www.youtube.com/watch?v=mNYlIcXynwE

43. Are you more drunk than you think?, http://fxn.ws/TqUdz9 • Women have a higher fat-to-water ratio than men do. • A 150-pound man holds more water than a 150-pound woman; after one drink, the woman will have a higher concentration of booze in her blood. That leads to greater intoxication. And her liver has to work harder to metabolize that alcohol, prolonging her buzz.  • For every drink a woman has, it’s the equivalent of a drink and a half for a same-sized man.

44. Reticular Connective Tissue Found in lymph node Figure 4.12d

45. Reticular Connective Tissue

46. Loose Connective Tissue LOOSE (AREOLAR) connective tissue This is the least specialized connective tissue. The main cell type in loose and dense connective tissue is a FIBROBLAST (a type of cell, not just a part of a cell). Fibroblasts are what make collagen and elastic fibers, and they also and repair wounds. Areolar is common in areas just deep to epidermis (upper dermis). It does NOT have much collagen as dense because it does not have many fibroblasts.

47. Areolar Connective Tissue Found in dermis Figure 4.12b

48. Dense Regular Connective Tissue DENSE REGULAR connective tissue • Dense regular and irregular connective tissue has lots of COLLAGEN FIBERS • Dense regular has more collagen than irregular. • Dense regular fibers have a pattern, and run in same direction • Even more strong than irregular, but only in one direction • Ligaments and tendons are dense regular CT. • Note: tendons are not muscle tissue; they are dense regular connective tissue.

49. Dense Regular Connective Tissue Figure 4.12f

50. NOTE: If you get injured, you’d rather break a bone than tear a ligament, why? • The number of fibroblasts is the same, but the ligament has a lot more collagen to be made by each fibroblast. • And the blood supply to bone is much better than a ligament.