1. Tissues

2. Tissues
Groups of cells that have specialized structural and functional roles
Four major types
Epithelial
Connective
Muscle
Nervous

3. Epithelial Covers organs Forms the inner lining of body cavities
Lines hollow organs
Always has a free surface, one that is exposed to the outside or to an open space internally
Basement Membrane: nonliving layer of connective tissue that anchors the tissue

4. Epithelial Tissue Lack blood vessels Cell readily divide
Nutrients diffuse from underlying connective tissues
Cell readily divide
Injuries heal rapidly
Skin cells, stomach and intestine lining are continually damaged and replaced
Tightly Packed with little intercellular material
Effective barriers: skin and mouth
Secretion, absorption, excretion, and sensory reception

5. Simple Epithelium Simple Squamous Epithelium
Single thin layer of flattened cells
Nuclei are broad and thin
Common site of diffusion and filtration
Line air sacs, capillaries, blood and lymph vessels
Easily damaged

6. Simple Epithelium continued
Simple Cuboidal Epithelium
Single layer of cubed shaped cells
Centrally located spherical nuclei
Cover the ovaries and lines most kidney tubules
Kidney functions in secretion and absorption
Glands of certain ducts: thyroid, pancreas, and liver
Secretes glandular products

7. More Simple Epithelium
Simple Columnar Epithelium
Elongated
Think tissue  protects underlying tissue
Single layer of cells
Nuclei located near the basement membrane
Line the uterus and most digestive organs
Stomach and small intestines
Secrete digestive fluids and absorb nutrients
Microvilli: cylindrical projections from cell membrane
Increase surface area  for increased absorption

8. Pseudostratified Columnar Epithelium
Appear stratified or layered, but are not
Possess cilia, which move constantly
Goblet cells scattered throughout secrete mucus
Cilia sweeps away
Line passage of respiratory system
Mucus cover linings trap dust and microorganisms
Cilia move the mucus and its captured particles upward and out

9. Stratified Squamous Epithelium
Layered cells  thick tissue
Cells divide in deep layers and newer cells push older one outward, where they flatten
Outer skin layer, epidermis
As they age, accumulate the protein keratin, then harden and die
tough, hard, waterproof covering
Blocks foreign invaders
Line the mouth, throat, vagina, and anal canal
Not keratinized

10. Stratified Cuboidal Epithelium
Two to three layers of cuboidal cells that form lining of lumen
More protection than single layer
Lines the larger ducts of mammary glands, sweat glands, salivary glands, and pancreas
Lining of developing ovary follicles and seminiferous tubules
female and male respectively

11. Stratified Columnar Epithelium
Several layers of cells
Superficial cells are elongated
Basal layer are cubed shaped
Male urethra
Parts of the pharynx

12. Transitional Epithelium
Specialized to change in response to tension
Inner lining of urinary bladder
Lines the ureters and part of the urethra
Provides an expandable lining

13. Glandular Epithelium
Specialized to produce and secrete substances into ducts or into body fluids
Found in glands
Exocrine glands: glands that secrete their products into ducts that open onto some internal or external surface
Merocrine Glands: watery, protein rich fluid
Apocrine Glands: lose small portions of their glandular cell bodies during secretion
Holocrine Glands: the entire cell lyses during secretion
Endocrine: secrete products into tissue fluid or blood

14. Connective Tissue

15. Functions of Connective Tissue
Binds structures
Provides support and protection
Serves as a framework
Fills spaces
Store fat
Produce blood cells
Protect against infection
Help repair tissue damage

16. General Characteristics
Farther apart than epithelial
Have an abundance of intercellular material between them, matrix
Fibers and ground substance
Can usually divide
Varying degrees of vascularity
Especially bone and cartilage
Some are flexible
Adipose

17. Major Cell Types Fixed: present in stable numbers
Fibroblasts: most common type
Large star shaped
Produce fibers by secreting proteins into the matrix
Mast cells: large widely distributed
Near blood vessels
Release heparin, prevent blood clotting
Release histamine: promotes some reaction of inflammation and allergies

18. Major Cell Types continued
Wandering: temporarily appear in tissue
Macrophages: originate as white blood cells
Specialized for phagocytosis
Function as scavengers and defensive cells that clears tissues of foreign particles

19. Connective Tissue Fibers
Produced by fibroblasts
Collagenous Fibers: thick threads of protein collagen
Grouped in long, parallel bundles
Slightly elastic and flexible
Great tensile strength
Components of:
Ligaments: bone to bone
Tendons: muscle to bone
White Fibers

20. Connective Tissue Fibers
Elastic Fibers: elastin protein
Branch, forming complex networks
Weaker than collagenous fibers
Stretch easier and resume original shape
Common In: Vocal Cords
Yellow Fibers
Reticular Fibers
Very thin collagenous fibers
Highly branched and form delicate supporting networks

21. Loose Connective Tissue
Areolar Tissues: forms delicate, thin membranes
Cells located some distance apart and separated by a gel-like matrix containing collagenous and elastic fibers
Binds the skin to the underlying organs and fills space between muscles
Beneath most epithelium

22. Adipose Tissue Fat Cushions joints and some organs Insulates for heat
Specialized form of connective tissue that develops when certain cells store fat in droplets within the cytoplasm and enlarge
Cushions joints and some organs
Insulates for heat
Stores energy
beneath the skin between muscles
around kidneys behind eyeballs
abdominal membrane surface of the heart
around certain joints

23. Dense Connective Tissue
Many closely packed, thick, collagenous fibers
Fine network of elastic fibers
Relatively few cells, mostly fibroblasts
Very strong
Poor blood supply  slow repair
Part of tendons and ligaments
Protective white layer of eyeball
Deeper skin layers

24. Cartilage Chondrocytes: cartilage cells
Perichondrium: protective tissue enclosing cartilaginous structures
Supplies nutrients
Lack of direct blood supply  slow healing
Rigid connective tissue
Support, framework and attachments
Protects underlying tissues
Structural models for developing bones

25. Types of Cartilage Hyaline Cartilage: most common
Very fine collagenous fibers in a matrix
White glass
Ends of bones in joints, soft part of nose, supporting rings of respiratory passage

26. Types of Cartilage continued
Elastic Cartilage: dense network of elastic fibers
More elastic and flexible
Ears & larynx
Fibrocartilage
very tough tissue, many collagenous fibers
Shock absorber: knees and pelvic girdle
Pads of intervertebral disks between vertebrae

27. Bone Most rigid connective tissue
Hardness: mineral salts between cells
calcium phosphate and calcium carbonate
Great amount of collagen
Supports body structures
Protects cranial and thoracic cavities
Attachment for muscle
Contain red marrow
forms WBC
Stores and releases inorganic chemicals, Ca and P

28. More about Bones Osteocytes: bone cells
Located in the lacuanae
Forms concentric circles
Osteon: layers of osteocytes around the osteonic canal
Contains blood vessels
Material can move rapidly between blood vessels and bone cells
Heals faster than cartilage

29. Blood
Transports materials between interior body cells and the external environment
Helps maintain homeostasis
Composed of formed elements suspended in a fluid matrix
Fluid Matrix: blood plasma
Formed Elements: RBC, WBC, platelets
Forms in red marrow in long bones

30. Muscle and Nervous Tissues

31. Muscle Tissue Contractile
Muscle Fibers: elongated cells that can shorten
Move body parts
As they contract, fibers pull at their attached ends
3 Types
Skeletal Muscle Tissue
Smooth Muscle Tissue
Cardiac Muscle Tissue

32. Skeletal Muscle Tissue
Muscle is attached to bone
Voluntary: consciously controlled
Contract when stimulated by nervous impulse then relax
Moves head, trunk, and limbs
Facial Expressions, write, talk, sing, chew, swallow, and breathe

33. Skeletal Muscle Tissue continued
Appearance
Long thread like fibers
Striations: alternating light and dark cross-markings
Each cell has many nuclei just beneath the cell membrane

34. Smooth Muscle Tissue Smooth  cells lack striations
Shorter than skeletal cells
Spindle-shaped
Single, centrally located nucleus
Comprises the walls of hollow internal organs
Stomach, intestines, urinary bladder, uterus, and blood vessels

35. Smooth Muscle Tissue continued
Involuntary: cannot be consciously stimulated
Moves food through digestive tract
Constricts blood vessels
Empties urinary bladder

36. Cardiac Muscle Tissue Only in the heart
Bulk of the heart
Pumps blood through the heart chambers into blood vessels
Cells: striated and joined end to end
Muscle fibers are branched
Connected in complex networks
Single nuclei
Intercalated disk: where it touches another cell
Specialized intercellular junction
Controlled involuntarily

37. Nervous Tissue Brain, spinal cord, and peripheral nerves
Neurons: basic cells
Send nerve impulses along cytoplasmic extensions, or nerve fibers
Single to: neutrons, muscles, or glands
Coordinated, regulate, and integrate many body functions

38. Nervous Tissue Neuroglial Cells
Support and bind the components of nervous tissue
Carry on phagocytosis
Supply nutrients to neurons  connecting with blood vessels