1. Chapter 05 Lecture Outline
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2. 5.1: Cells are Organized into Tissues
In complex organisms, cells are organized into tissues
Tissues: Groups of similar cells with a common function
The study of tissues is called histology.
There are 4 major types of tissues in the body:
1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
4. Nervous tissue

3. Intercellular Junctions
Tight junctions:
Membranes between cells
merge and fuse
Located among cells that form
linings, sheetlike layers
Blood-brain barrier
Desmosomes:
Form “spot welds” between cells
Structural reinforcement
Located among outer skin cells
Gap junctions:
Tubular channels between cells
Molecules can move between cells
Located in cardiac muscle cells

4. 5.2: Epithelial Tissue General Characteristics:
Covers organs and body surface
Lines cavities and hollow organs
Makes up glands
Have a free surface on outside, and basement membrane on inside
Usually lack blood vessels; nutrients diffuse from underlying connective tissue
Cells readily divide; injuries heal rapidly
Cells are tightly packed
Classified according to cell shape and number of cell layers
Shapes: squamous (flat), cuboidal (cube-shaped), columnar (tall)
Layers: simple (one layer of cells), stratified (2 or more layer of cells), or
pseudostratified (appears layered, but is not)

5. Epithelial Tissue Types
Simple squamous:
Single layer of thin, flat cells
Substances pass easily through
Thin & delicate, can be damaged
Found in diffusion & filtration sites
Lines air sacs (alveoli) & capillaries
Lines blood & lymphatic vessels
Simple cuboidal:
Single layer of cube-shaped cells
Secretion and absorption
Lines kidney tubules, thyroid
follicles
Covers ovaries
Lines ducts of some glands

6. Epithelial Tissue Types
Simple columnar:
Single layer of elongated cells
Nuclei usually at same level,
near basement membrane
Sometimes have cilia
Sometimes have microvilli
Sometimes have goblet cells
(secrete mucus)
Secretion and absorption
Lines uterus, stomach, intestines
Pseudostratified columnar:
Single layer, but appears layered
Nuclei at 2 or more levels
Cells vary in shape
Often has cilia, goblet cells
Protection from infection
Lines respiratory passageways

7. Epithelial Tissue Types
Stratified squamous:
Many cell layers; thick
Protective layer
Outermost cells are flat
Deeper cells are cuboidal
New cells form, push older cells
toward free surface
Outer layer of skin (keratinized)
Lines oral cavity, vagina, anal canal
Stratified cuboidal:
2-3 layers of cube-shaped cells
More protection than 1 layer
Lines ducts of mammary, sweat,
& salivary glands, and pancreas

8. Epithelial Tissue Types
Stratified columnar:
Top layer of elongated cells
Cube-shaped cells in
deeper layers
Lines part of male urethra,
ducts of exocrine glands
Transitional (uroepithelium):
Many cell layers
Cube-shaped and elongated
cells
Changes shape with increased
tension; stretches
Line urinary bladder, ureters,
and part of urethra

9. Glandular Epithelium
Glandular Epithelium: Composed of cells that produce and secrete substances into ducts or body fluids
There are 2 types of glands:
Endocrine glands secrete into tissue fluid or blood
Exocrine glands secrete into ducts that open onto surface
2 structural types of exocrine glands:
Unicellular:
Composed of one cell, such as a goblet cell (secretes mucus)
Multicellular:
Composed of many cells
Sweat glands, salivary glands, etc.
Simple or compound

10. Structural Types of Exocrine Glands
Simple: duct does not branch Compound: duct branches before it reaches secretory portion Tubular: consist of epithelial-lined tubes Alveolar: terminal portions form saclike dilations

11. Types of Glandular Secretion
Merocrine Glands: Secrete fluid products by exocytosis; salivary & sweat glands, pancreas Apocrine Glands: Lose small part of cell during secretion; mammary & ceruminous glands Holocrine Glands: Release entire cells filled with product; sebaceous glands

12. 5.3: Connective Tissues General characteristics:
Most abundant tissue type
Cells are farther apart than epithelial cells; contain matrix between cells
Many functions:
Bind structures together
Provide support and protection
Serve as frameworks
Fill spaces
Store fat
Produce blood cells
Protect against infections
Help repair tissue damage
Extracellular matrix consists of protein fibers and ground substance; consistency varies from fluid to semisolid to solid
Most have good blood supply, and are well-nourished, but vascularity varies among tissue types
Most cells can divide

13. Major Cell Types of Connective Tissue
Fibroblasts:
Most common fixed cell
Large star-shaped cell
Secrete fibers into extracellular
matrix
Macrophages (Histiocytes):
Usually attached to fibers, but
can detach and wander
Conduct phagocytosis
Defend against infection

14. Major Cell Types of Connective Tissue
Mast Cells:
Large, fixed cells
Release heparin to prevent
blood clotting
Release histamine, which causes
inflammatory response

15. Connective Tissue Fibers
Fibroblasts produce 3 types of fibers in connective tissue:
Collagen Fibers:
Thick threads of collagen, the body’s main structural protein
Great tensile strength and flexible, slightly elastic
Found in ligaments and tendons
Elastic (Yellow) Fibers:
Composed of elastin protein; branching
Can stretch and return to original shape
Not as strong as collagen fibers
Found in vocal cords, respiratory air
passages
Reticular Fibers:
Thin, branching fibers of collagen
Form delicate, supporting networks
Found in spleen, liver

16. Categories of Connective Tissue
Connective tissues can be classified in 2 major categories:
Connective Tissue Proper:
Loose connective tissues:
- Areolar
- Adipose
- Reticular
Dense connective tissues:
- Dense Regular
- Dense Irregular
- Elastic
Specialized connective tissues:
Cartilage
Bone
Blood

17. Connective Tissue Types
Areolar Connective Tissue:
Forms thin, delicate membranes
Cells are mainly fibroblasts
Gel-like ground substance
Collagenous & elastic fibers
In subcutaneous layer
Beneath most epithelia, where
it nourishes nearby epithelial cells
Adipose Tissue:
Adipocytes store fat
Push their nuclei to one side
Crowd out other cell types
Cushions and insulates
Beneath skin (subcutaneous layer)
Behind eyeballs
Around kidneys and heart
Spaces between muscles

18. Connective Tissue Types
Reticular Connective Tissue:
Composed of thin reticular fibers
Supports walls of internal organs
Walls of liver, spleen
Dense Regular Connective Tissue:
Closely packed collagenous fibers
Fine network of elastic fibers
Most cells are fibroblasts
Very strong, withstands pulling
Binds body parts together
Tendons, ligaments, dermis
Poor blood supply; slow to heal

19. Connective Tissue Types
Dense Irregular Connective Tissue:
Randomly organized, thick,
interwoven collagenous fibers
Can withstand tension exerted
from different directions
Dermis of skin
Around skeletal muscles
Elastic Connective Tissue:
Abundant yellow elastic fibers
Some collagenous fibers
Fibroblasts
Attachments between bones
of spinal column
Walls of hollow organs, such
as large arteries, airways
Parts of heart
Elastic quality, stretches

20. Connective Tissue Types
Cartilage:
A rigid, specialized connective tissue
Support, framework, attachments
Protection of underlying tissue
Models for developing bone
Matrix contains collagen in gel-like ground substance
Chondrocytes (cartilage cells) in lacunae (chambers), surrounded by matrix
Lacks blood supply; heals slowly
Covered by perichondrium (connective tissue), which provides some nutrients to the cartilage
3 types of cartilage: Hyaline, Elastic, and Fibrocartilage

21. Connective Tissue Types
Hyaline cartilage:
Most common type
Fine collagen fibers
Ends of bones in joints
Nose, respiratory
passages
Embryonic skeleton
Elastic cartilage:
Flexible, due to elastic
fibers in matrix
External ear, larynx

22. Connective Tissue Types
Fibrocartilage:
Very tough, due to many collagenous fibers
Shock absorber
Intervertebral discs
Pads of knee and pelvic girdle

23. Connective Tissue Types
Bone (Osseous Tissue):
Most rigid connective tissue
Solid matrix, composed of mineral (Ca) salts & collagen
Supports structures
Protects vital structures
Produces blood cells
Stores & releases Ca, P
Attachment sites for muscles
Forms skeleton
Contain osteocytes (bone cells) in lacunae
2 types: compact and spongy

24. Connective Tissue Types
Compact Bone:
Osteoblasts deposit matrix in lamellae (layers)
Lamellae occur in rings around central canals
Osteocytes + matrix + central canal form cylindrical units called osteons
Osteons are cemented together to form compact bone
Central canals contain blood vessels; bone is well-nourished, heals more quickly than cartilage

25. Connective Tissue Types
Blood:
Cells suspended in fluid matrix called plasma
Red blood cells transport gases
White blood cells defend again infection
Platelets help in blood clotting
Transports substances around body

26. 5.4: Types of Membranes Membranes are sheets of cells
Epithelial membranes are composed of epithelial and connective tissue; cover body surfaces and line cavities
3 types of epithelial membranes:
1. Serous membranes:
- Line body cavities that do not open to outside of body
- Inner linings of thorax and abdomen; covers organs
- Simple squamous epithelium + areolar connective tissue
- Secrete serous fluid for lubrication, reducing friction
2. Mucous membranes:
- Line cavities and tubes that open to the outside of body
- Lining of digestive, respiratory, urinary, and reproductive tracts
- Epithelium + areolar connective tissue
- Goblet cells secrete mucus

27. Types of Membranes 3. Cutaneous membrane: - Covers body surface
- Commonly called skin
- Part of integumentary system
Synovial membranes:
- Different from epithelial membranes
- Composed entirely of connective tissue
- Line joint cavities

28. 5.5: Muscle Tissues General Characteristics: Skeletal muscle tissue:
Muscle cells are also called muscle fibers
Contractile; can shorten and thicken
3 types of muscle tissue: skeletal, cardiac, and smooth
Skeletal muscle tissue:
Attached to bones
Striated
Voluntary
Multinucleated cells
Long cylindrical cells
Stimulated by nerve
cells

29. Muscle Tissues Smooth muscle tissue: Cardiac muscle tissue:
Non-striated
Spindle-shaped fibers
Walls of hollow organs
Walls of blood vessels
Involuntary
Cardiac muscle tissue:
Only in wall of heart
Branching cells
Striated
Intercalated discs

30. 5.6: Nervous Tissue Nervous tissues:
Found in brain, spinal cord, peripheral nerves
Main cells are neurons, which are specialized for communication, via conduction of nerve impulses (sensory reception, motor control)
Neurons coordinate, integrate, and regulate body functions
Neuroglia support and nourish neurons

31. Muscle and Nervous Tissues