Cells are the basic unit of life

Transcription

1 Ch. 4 Tissues

2 Cells are the basic unit of life Organism Organ System Organs Tissues Cells

3 Living thing A group of organ systems working together

4 Group of organs working together Each system has a specific job Ex: Digestive system Break down food Depends on other systems too

5 Two or more tissues working together Ex: Heart Stomach Leaf Root

6 Similar cells that work together to perform a specific function Organized into groups and layers Four basic types: 1) Epithelial 2) Connective 3) Muscle 4) Nervous

7 Epi= upon Widespread Cover and line internal organs Cover body surfaces Compose glands

8 Protection Skin Lining of respiratory tract Absorption Lining of digestive tract Secretion Glands Excretion Sensory reception

9 Always one free surface = Apical Exposed to outside or to open internal space Other surface = Basal = Basement membrane Lower surface Anchored to connective tissue Nonliving layer Thin

10 Avascular No blood supply Nutrients diffuse from underlying connective tissue (vascular) Can regenerate Readily divide Heal rapidly Ex: skin, stomach, intestines

11 Tightly packed Little intercellular material Good protective barriers Ex: Outer layer of skin Lining of stomach Lining of mouth

12 9 Types Most have two names: First name Number of layers Simple Stratified Second name Shape of cells Squamous Cuboidal Columnar

13 Usually very thin Single layer of cells

14 A) Simple squamous epithelium Single layer Thin, flat cells Easily damaged Broad, thin nuclei Squamous =flat

15 Cells fit together tightly Like floor tiles Fried egg shape Usually form membranes Filtration Diffusion Ex: Capillaries Alveoli Body cavity linings

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18 B) Simple cuboidal epithelium Single layer Cube shaped Central, spherical nucleus Covers ovaries Common in glands and ducts Salivary glands Pancreas Liver Thyroid Kidneys

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20 C) Simple columnar epithelium Single layer Elongated like columns thick Nuclei located at about the same level near basement membrane May have cilia on free surface

21 Nonciliated Lines uterus and most digestive organs Ciliated Secretion and absorption microvilli tiny extentions that increase surface area Fallopian tubes Moves egg

22 Goblet cells Secrete mucus (protective fluid) onto free surface Mucous membranes Line body cavities that open to outside

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25 D) Pseudostratified Columnar Epethelium Pseudo = false Appears layered, but is not Nuclei at different levels Many have cilia and goblet cells Mainly absorption and secretion Line respiratory tract

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27 Stratified Two or more layers Thicker More durable Function in protection

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29 E) Stratified squamous epithelium Several layers thick Cells divide in deeper layers New ones push old ones up

30 Cells at free edge are squamous Cuboidal at basement membrane Sometimes cells alive on free surface: Stays soft and moist Ex: Mouth Esophagus Vagina Anal canal

31 Forms Epidermis outer layer of skin Dead cells on free surface Keratin protein that forms in old cells Keratinization produces dry, tough, protective covering Effective barrier Good stuff in, bad stuff out

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34 F) Stratified cuboidal epithelium Two or three layers Line lumen space within tubular structure Ducts of: Sweat glands Salivary glands Mammary glands Pancreas Parts of reproductive system

35 G) Stratified columnar epithelium Several layers Top cells = columnar (elongated) Bottom cells = cube shaped Rare Male urethra and vas deferens Pharynx

36 H) Transistional Epithelium Specialized Stretches as tension increases Forms linings Urinary system Cells change shape Cuboidal then flatten as stretched

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38 I) Glandular Epithelium Consists of cells (glands) that make and secrete substances into ducts or body fluids Usually found within columnar or cuboidal epithelia

39 Two major types 1) Exocrine Secrete products into ducts that open onto internal or external surface Ex: Sweat glands Oil glands Liver Pancreas

40 A) Merocrine Most common release water, protein rich fluids by exocytosis Ex: Salivary glands Pancreatic glands Sweat glands

41 i) Serous cells watery secretion, many enzymes (serous fluid) Common in linings of body cavities ii) Mucous cells secretion is thicker (mucus) Rich in mucin (glycoprotein) Common in digestive and respiratory systems

42 Exocrine Glands B) Apocrine lose small portions of cell body during secretion Ex: mammary glands and external ear canal

43 C) Holocrine entire cell lyses during secretion Ex: Sebaceous glands of skin

44 Two major types: 2) Endocrine Ductless Products secreted into tissue fluid or blood Ex: Thyroid Adrenal Pituitary

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47 Characteristics: Cells farther apart than epithelial Abundance of matrix Intercellular material Nonliving Cells can usually divide Most vascular Except tendons, ligaments, cartilage

48 Functions: Bind structures Support and protection Framework Fill spaces Store fat Produce RBCs Prevent infections Repair tissue damage

49 Cell types: A) Fixed cells stable # s i) Fibroblasts most common Large, star-shaped Produce fibers ii) Mast cells large Release heparin and histamine

50 Cell Types: B) Wandering cells temporary, usually in response to infection i) Macrophages (histocytes) Originate from WBCs Phagocytosis Scavengers Defenders

51 Macrophages and Fibroblasts

52 3 Types of fibers: All produced by fibroblasts 1) Collagenous ( white ) thick threads of protein collagen High tensile strength ability to resist pulling Flexible, but only slightly elastic Compose ligaments (connect bone to bone) and tendons (bone to muscle) Dense connective tissue

53 2) Elastic ( yellow ) made of protein elastin Complex, branching Weaker Stretchy Ex: vocal cords

54 3) Reticular Very thin Collagenous Highly branched Delicate support networks

55 Two categories: 1) Connective tissue proper A) loose B) adipose C) dense 2) Specialized Connective tissues A) cartilage B) bone C) blood

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57 1) Loose connective tissue = Areolar tissue Most widely distributed Soft and pliable Spiderwebby appearance

58 Mainly fibroblasts Connective tissue glue Binds skin to organs Fills spaces b/w muscles Vascular Nourishes epithelial cells

59 Tissue soaks up excess water Inflammation Edema - An area swells and becomes puffy

60 2) Adipose tissue = fat Adipocytes Store fat in droplets in cytoplasm Nucleus near edge Signet ring cells

61 Locations: Beneath skin Behind eyeballs Around kidneys and certain joints Heart s surface Abdominal membranes Functions: Insulate, cushions, store energy

62 3) Dense connective tissue Closely packed collagen fibers and network of elastic fibers Short rows of fibroblasts separated by collagen fibers Very strong Tendons Ligaments Sclera of eye Poor blood supply Slow healing

63 1) Cartilage Rigid, but flexible Chondrocytes cartilage cells Infrequent division Occupy lacunae small chambers No direct blood supply Perichondrium encloses cartilaginous structure Provides blood supply

64 1) Hyaline cartilage Most abundant Fine collagen fibers Matrix with white, glassy appeance Found: Ends of bones Nose Rings in resp. system

65 2) Elastic Elastic fibers More flexible Found: External ears Larynx 3) Fibrocartilage Tough Many collagenous fibers Found: Intervertebral disks Knees Pelvic girdle

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67 2) Bone Most rigid Layers of hard matrix Made of collagen fibers and calcium salts Protects and supports Active Heals well

68 Lamellae concentric layers of bone matrix that form around: Central canals (Haversian canals) longitudinal tubes Contain blood vessel Lacunae hollow cavity Contain osteocytes bone cells

69 Osteon cylindershaped unit of osteocytes and intercellular material

70 3) Blood Vascular Exchanges materials Helps maintain homeostasis Formed elements = RBCs,WBCs,platelets Plasma = fluid matrix

71 Specialized to contract Moves body parts Elongated cells are called muscle fibers

72 C) Cardiac A) Skeletal B) Smooth

73 Voluntary conscious control flesh Gross body motions Connected to bones or skin

74 Cells: Long Cylindrical Multinucleated Nuclei near edge Striated

75 Involuntary Visceral muscle Found in walls of hollow organs Stomach Blood vessels Uterus Cells: No striations Spindle-shaped One nucleus Central

76 C) Cardiac muscle Involuntary Found in heart only! Contracts Heart pumps Propels blood Cardiac muscle cells Striations Branching One nucleus Intercalated disks Where one cell touches another

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78 4) In brain, spinal cord, and nerves Neurons = nerve cells Receive and conduct impulses Coordinate, regulate, and integrate many body functions Neuroglial Cells = supporting cells Support and bind Help supply nutrients Connect cells to blood vessels Carry out phagocytosis

79 Neuron Neuroglial cells

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81 Zygote Fertilized egg Embryonic cells begin to specialize By birth organs are well developed and functioning Body continues to grow

82 Cell division Most cells undergo mitosis until end of puberty Adult body size reached Then only certain cells routinely divide Ex: Skin Intestinal cells

83 Cell division Liver cells stop dividing at adult size Still have ability if some cells need to be replaced Amitotic tissue Lose ability to divide Ex: Heart muscle Nerve tissue

84 Aging Begins once maturity is reached Debate over aging: Result of chemical insults? Alcohol Pollutions Shortages of key substances Cumulative effect