Histology

1. Histology W.U. : Using your medical dictionary, what do you think Histology is the study of?

2. Histology • The study of different types of tissues • Tissue: Cells working together in functionally related groups

3. Histology • Separated into four major categories based on their function and the embryonic tissue of origin

4. Epithelial Tissue • Location: • Lines nearly every cavity and surface of the human body • Form glands • Function: • Protect the tissues they cover • Regulate gas and nutrient exchange • Secrete substances such as sweat, hormones, mucus, and enzymes • Provide sensation with the environment

5. Epithelial • Classification: • First name of tissue indicates the number of layers • Simple: One layer of cells • Stratified: More than one layer of cells

6. Epithelial • Classification • Last name of tissue describes the SHAPE of cells • Squamous: cells wider than tall • Cubodial: cells are as wide as tall, as in “cubes” • Columnar: cells are taller than they are wide, like columns

7. Epilthelial • Put it all together… • Simple squamous • Simple columnar • Stratified cubodial • Special epithelial tissues • Pseudostratified • Transitional

8. Epithelial • Special characteristics: • Cells are packed tightly together, forming a protective layer around organs • High capacity for regeneration • Produce fluids for lubricating tissues and organs • Avascular: No capillaries that directly nourish the cells • Cells get what they need through diffusion of nutrients through the basement membrane

9. Simple Squamous Epithelium • Single layer of flat cells with disc-shaped nuclei • Function: • Passage of materials by passive diffusion and filtration • Secrete lubricating substances in serosae

10. Simple Squamous Epithelium • Location • Renal corpuscles • Alveoli of lungs • Lining of heart, blood, and lymphatic vessels • Lining of ventral body cavity

11. Simple Cuboidal Epithelium • Single layer of cube-like cells with large, spherical nuclei • Function: • Secretion and absorption

12. Simple Cuboidal Epithelium • Location: • Kidney tubules • Secretory portions of small glands • Ovary and Thyroid follicles

13. Simple Columnar Epithelium • Single layer of column-shaped cells with oval nuclei • Some may have cilia • Function: • Absorption • Secretion of mucus, enzymes, and other substances • Ciliated type propels mucus or reproductive cells by ciliary action

14. Simple Columnar • Location: • Non-ciliated: lines digestive tract, gallbladder, ducts of some glands • Ciliated form: lines small bronchi, uterine tubes, uterus

15. Connective Tissues • Most abundant tissue type in the body • Ex: blood, bone, cartilage, tendons, ligaments… • Made up of fibers and extracellular components in the embedded in fluid • Types of Connective Tissues • Loose Connective Tissue • Dense Connective Tissue • Cartilage • Other Tissues

16. Connective Tissue • Function: • Protect • Store energy • Transport • Insulate • Connect all body tissues

17. Loose Connective Tissue • Areolar: • Binds cells and fibers together, allows movement • Found under skin, surrounds capillaries • Adipose: • Fat, stores nutrients, insulates, protects organs • Found under skin, around kidneys, within abdomen • Reticular: • Allows for structure and flow of substances • Found in lymph nodes, bone marrow, spleen

18. Dense Connective Tissue • Regular: • Make up tendon and ligaments, tightly organized bundles of collagen • Found in tendons, ligaments, fascia around muscles • Irregular: • Make up the dermis, tight bundles of collagen that are unorganized • Found in the dermis of skin, submucosa of digestive tract

19. Cartilage • Hyaline: • Provides support while still being pliable, most abundant form • Found in the ends of long bones, nose, trachea, and larnyx • Elastic • Provides support while still able to stretch • Supports external ear, epiglottis

20. Cartilage • Fibrocartilage: • Provides strong support and handles heavy pressure • Found in intervertebral discs, pubic symphysis, discs of knee joints

21. Other Tissues… • Bone • Support, hard tissue of collagen fibers and calcium surrounding osteocytes • Blood • Tissue that contains red blood cells, proteins, and plasma

22. Muscle Tissue • Cells are extremely long and contain protein fibers capable of contracting • Separated into 3 main types: • Skeletal muscle tissue • Smooth muscle tissue • Cardiac muscle tissue

23. Skeletal Muscle Tissue • Voluntary muscle • Can be contracted voluntarily • Function in movement and maintenance of posture • Visible striations • Makes up the muscles that are attached to our skeleton

24. Smooth Muscle Tissue • Involuntary muscle • Muscle does not contract voluntarily • Lines most of the organs of the body • No visible striations • Found in: • GI Tract • Respiratory Tract • Blood vessels • Bladder • Uterus

25. Cardiac Muscle • Heart, extremely dense, strong tissue • Involuntary • Large number of mitochondria to provide energy for the continuous contracting of the heart • Striated like muscle tissue

26. Nervous Tissue • Found in the brain, spinal cord, and nerves • Consists of 2 main cells • Neurons • Neuroglia cells • Responsible for communication

27. TED Talks • Could tissue engineering mean personalized medicine? • Anthony Atala: Growing new organs