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B ODY T ISSUES. O VERVIEW  Human body starts with one cell  Division makes millions of cells  Each specialized for particular functions  Some are.

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Presentation on theme: "B ODY T ISSUES. O VERVIEW  Human body starts with one cell  Division makes millions of cells  Each specialized for particular functions  Some are."— Presentation transcript:

1 B ODY T ISSUES

2 O VERVIEW  Human body starts with one cell  Division makes millions of cells  Each specialized for particular functions  Some are so specialized, they can create hazards  Ex. Heart cells  Groups of similar cells that are similar in structure and function: tissues

3 T YPES OF T ISSUES  Epithelium (covering)  Connective (support)  Nervous (control)  Muscle (movement)  All interweave to form the fabric of the body  Tissues organized into organs  One organ can be composed of several tissue types

4 E PITHELIAL T ISSUE  Also called epithelium  Lining, covering, and glandular  Forms glands  Covers all free body surfaces  Versatile cells  Outer skin layer, and lining of body cavities  Every substance entering or leaving must pass through these cells

5 S PECIAL C HARACTERISTICS  Except for glandular, they fit closely together to form continuous sheets  Always have one free surface (apical surface): exposed to body’s exterior or the cavity of an internal organ  Lower surface rests on a basement membrane, structureless material secreted by cells  No blood supply of their own (avascular); depend on diffusion from capillaries  Regenerate themselves very easily

6 C LASSIFICATION OF E PITHELIUM  Two names  First name is for number of cells: simple (one) or stratified (more than one)  Second name describes shape: squamous (flattened), cuboidal (cube-shaped), and columnar (column-shaped)  Names are combined  *Stratified epithelia are named for the cells at the free surface of the membrane, not the those resting on the basement membrane

7 S IMPLE E PITHELIA  Most concerned with absorption, secretion, and filtration  Simple Squamous epithelium  Single layer resting on basement membrane  Fit closely together  Usually forms membranes that use diffusion: air sacs of lungs, walls of capillaries  Also forms serous membranes or serosae: slick membranes lining ventral body cavity and cover organs in ventral cavity

8 S IMPLE E PITHELIA CONTD.  Simple Cuboidal Epi.  One layer resting on basement membrane  Common in glands and ducts: salivary glands and pancreas  Forms walls of the kidney tubules, and covers surface of the ovaries

9 S IMPLE E PITHELIA CONTD.  Simple Columnar Epi.  One layer of tall cells  Fit close together  Goblet cells: produce a lubricating mucus, often seen in this type of epithelium  Lines entire length of digestive tract from stomach to anus  *Epithelial membranes that line body cavities open to the exterior are called mucous membranes or mucosae

10 S IMPLE E PITHELIA CONTD.  Pseudostratified Columnar Epi.  Rest on basement membrane  Cells are different heights, and nuclei appear at different heights above basement  Give false (pseudo) impression of stratified  Mainly absorption and secretion  Pseudostratified ciliated columnar epithelium Ciliated, lines most of respiratory tract Goblet cells produce mucus to trap dust and debris

11 S TRATIFIED E PITHELIA  Two or more cell layers  More durable than simple  Primarily for protection  Stratified Squamous Epithelium  Most common stratified  Usually several layers  Free edge are squamous, closer to basement are cuboidal or columnar  Found in “high friction” areas: esophagus, mouth, other parts of skin

12 S TRATIFIED E PITHELIA  Stratified Cuboidal and Columnar Epithelia  Usually just two cell layers with (at least) the surface cells being cuboidal  Surface cells of stratified columnar are columnar, but its basal cells vary in size and shape  Both are fairly rare  Found mainly in the ducts or large glands

13 S TRATIFIED E PITHELIA  Transitional Epithelium  Highly modified  Stratified squamous epithelium  Forms lining of only a few organs: bladder, the ureters, and part of the urethra  All part of the urinary system and undergo considerable stretching  Basal layer are cuboidal or columnar; those at the free surface vary in appearance  Stretching changes shape, cells can flatten and become squamous-like

14 G LANDULAR E PITHELIA  Gland: consists of one more cells that make and secrete a particular product  Secretion: typically contains protein molecules in an aqueous fluid  Noun and verb: glandular cells obtain needed materials from the blood and use them to make their secretion, which they then discharge  Two types:  Endocrine glands: no connection to surface (ductless), secrete hormones through diffusion  Exocrine glands: retain ducts, secretions empty to surface: sweat and oil glands, liver and pancreas, internal and external

15 C ONNECTIVE T ISSUE  Connects body parts  Found everywhere in body  Most abundant and widely distributed  Protect, support, bind other tissues together  Most are well vascularized (good blood supply)  Exceptions: tendons and ligaments have poor and cartilage has none (tend to heal slower than the others)  Extracellular matrix: nonliving substance found outside of these cells

16 E XTRACELLULAR M ATRIX  Only found in connective tissue  Produced by the connective tissue cells then secreted to their exterior  Two main elements:  Structureless ground substance: water + adhesion proteins and large charged polysaccharide molecules; like the “glue” between these cells  Fibers: collagen (white) very strong; elastic (yellow) stretching; reticular (fine collagen fibers) make up internal “skeleton” of soft organs such as spleen

17 E XTRACELLULAR M ATRIX  Because of matrix, connective tissue is able to form a soft packing tissue around other organs, to bear weight, and to withstand stretching and other abuses  Varies depending on tissue type:  Fat tissue is mostly cells and the matrix is soft  Bone and cartilage have very few cells and large amounts of hard matrix which makes them strong

18 T YPES OF C ONNECTIVE T ISSUE  From most rigid to softest:  Bone  Cartilage  Dense Connective tissue  Loose Connective tissue  Blood

19 B ONE  Called Osseous tissue  Composed of bone cells sitting in cavities called lacunae  Surrounded by layers of a very hard matrix that contains calcium salts and collagen fibers  Exceptional ability to protect and support

20 B ONE P ICTURE

21 C ARTILAGE  Less hard and more flexible than bone  Found only in a few places  Most widespread is hyaline cartilage: lots of collagen fibers, glassy, blue-white appearance  Forms larynx, attaches ribs to breastbone, covers the ends of bones; skeleton of fetus  Fibrocartilage: highly compressible, forms disks between the vertebrae of spinal column  Elastic Cartilage: found where elasticity is desired; external ear

22 H YALINE C ARTILAGE P ICTURE

23 F IBROCARTILAGE P ICTURE

24 E LASTIC C ARTILAGE P ICTURE

25 D ENSE C ONNECTIVE T ISSUE  Also called dense fibrous tissue  Collagen fibers as its main matrix element  Between collagen fibers are rows of fibroblasts (fiber-forming cells)  Forms strong, rope-like structures such as tendons (attach skeletal muscles to bones) and ligaments (connect bones to bones at joints)  Also makes up lower layers of skin (dermis), arranged in sheets

26 D ENSE C ONNECTIVE T ISSUE P ICTURE

27 L OOSE C ONNECTIVE T ISSUE  Softer and have more cells and fewer fibers  3 types:  Areolar: most widely distributed of connective; soft, pliable, “cobwebby”; cushions and protects; universal packing tissue; holds internal organs together and in place; lamina propria underlies all mucous membranes; all types of fibers forming loose network; provides reservoir of water and salts for surrounding tissues; inflammation in the body causes this tissue to soak up excess fluid like a sponge which causes it become puffy: edema; phagocytes wander through looking for debris to destroy

28 A REOLAR T ISSUE P ICTURE

29 A DIPOSE T ISSUE  Commonly called fat  Areolar with fat cells dominate  Fat cells = signet ring cells: cells are full of oil – pushes nucleus to outer rim of cell  Forms subcutaneous tissue beneath skin  Insulates and protects from heat and cold  Protects some organs: kidneys, eyeballs in sockets  Fat depots in body: hips and breasts where fat is stored and available for energy if needed

30 A DIPOSE T ISSUE P ICTURE

31 R ETICULAR T ISSUE  Delicate network of interwoven reticular fibers associated with reticular cells  Forms the stroma: internal framework, which can support many free blood cells (mostly lymphocytes) in lymphoid organs such as lymph nodes, the spleen, and bone marrow

32 R ETICULAR T ISSUE P ICTURE

33 B LOOD  Vascular tissue  Consists of blood cells, surrounded by nonliving, fluid matrix called blood plasma  “fibers” in blood are soluble proteins that only become visible during clotting  Transport vehicle for the cardiovascular system  Carries nutrients, wastes, respiratory gases, and many other substances

34 B LOOD T ISSUE P ICTURE

35 M USCLE T ISSUE  Highly specialized to contract or shorten  Produce movement  Three types:  Skeletal muscle  Cardiac muscle  Smooth muscle

36 S KELETAL M USCLE  Packaged by connective tissue sheets into organs called skeletal muscles, which are attached to the skeleton  Controlled voluntarily (consciously)  Form the flesh of the body: the muscular system  When they contract they pull on bones or skin  Cells are long, cylindrical, multinucleate, and striations (stripes)  Often called muscle fibers

37 S KELETAL M USCLE T ISSUE

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39 C ARDIAC M USCLE  Found only in heart  Has striations  Uninucleate  Short  Branching cells that fit tightly together at junctions called intercalated discs  Allow for rapid conduction of electrical impulses  Controlled involuntarily

40 C ARDIAC M USCLE T ISSUE

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42 S MOOTH M USCLE  Also called visceral muscle  No striations visible  Single nucleus, and spindle shaped (pointed at ends)  Walls of hollow organs: stomach, bladder, uterus, and blood vessels  Contracts slower than other types  Peristalsis: wavelike motion that keeps food moving through small intestine

43 S MOOTH M USCLE T ISSUE

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45 N ERVOUS T ISSUE  Cells called neurons  Receive and conduct electrochemical impulses from one body part to another  Irritability and conductivity are major functions  Unique structure  Cytoplasm drawn out into long processes (extensions) as much as 3 ft or more in the leg  Supporting cells: insulate, support, and protect the delicate neurons  Make up nervous system: brain, spinal cord, and nerves

46 N ERVOUS T ISSUE


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