HOLE S ANATOMY CHAPTER 5, PART II Lecture notes I. Connective Tissue A. Structure 1. have few cells that are spaced apart and can divide; two categories: a. fixed cells cells that are present in tissue in stable numbers: two types: 1) fibroblasts most common type of fixed cell in connective tissue a) large, star-shaped cells b) produce fibers by secreting proteins into the matrix 2) mast cells a) large cells; widely distributed throughout tissue b) located near blood vessels c) release heparin to prevent clotting d) release histamine to promote inflammatory & allergic reactions b. wandering cells temporarily appear in tissues; usually in response to injury or infection 1) macrophages a) originate as white blood cells b) almost as numerous as fibroblasts in some tissue c) specialized for phagocytosis; clear tissue of foreign particles 2. have a great amount of matrix (intercellular materials) between cells a. consists of fibers produced by fibroblasts; three types 1) collagenous fibers thick threads of the protein collagen a) grouped in long, parallel bundles b) flexible c) slightly elastic d) have great tensile strength (resist pulling force) e) important components of body parts that hold structures together, such as i) ligaments connect bones to bones ii) tendons connect muscles to bones f) white fibers term used for collagen fibers because when tissue contains a large amount of collagenous fibers, they appear white 2) elastic fibers threads of the protein elastin a) thin, branching fibers that form complex networks b) weaker than collagenous fibers c) stretch easily & can resume original lengths & shapes d) common in body structures that are frequently stretched (ex. vocal cords) 1
e) yellow fibers name for elastic fibers because when abundant in tissue, tissue appears yellowish 3) reticular fibers very thin collagenous fibers a) highly branched b) form delicate supporting networks in various tissues b. consists of ground substances vary from fluids to solids 3. Vascular have blood supply in varying degrees based on type of tissue 4. Range from rigid to flexible to fluid in nature B. Functions of connective tissues 1. bind structures 2. provide support and protection 3. serve as frameworks 4. fill spaces 5. store fat 6. produce blood cells 7. protect against infections 8. help repair tissue damage C. Types of Connective Tissue 1. Loose Connective Tissue or Areolar Tissue 1) cells are mainly fibroblasts 2) cells are far apart 3) cells separated by a gel-like matrix that contains many collagenous & elastic fibers 4) has many blood vessels 1) forms delicate, thin membranes throughout the body 2) binds skin to underlying organs 3) fills spaces between muscles 4) nourishes epithelial cells (lies beneath most layers of epithelium) 2. Adipose Tissue or Fat 1) specialized form of connective 2) develops when cells store fat in droplets within their cytoplasm & enlarge 3) enlarged cells become so numerous that they crowd other cell types b. Location 1) beneath the skin 2) in spaces between muscles 3) around the kidneys 4) behind the eyeballs 5) in certain abdominal membranes 6) on surface of the heart 7) around certain joints 2
c. Functions 1) cushions joints & some organs (ex. kidneys) 2) insulates beneath the skin 3) stores energy in fat molecules 3. Dense Connetive Tissue 1) many closely packed, thick collagenous fibers 2) fine network of elastic fibers 3) relatively few cells (mostly fibroblasts) 4) poor blood supply makes tissue repair slow 1) binds body parts together ( tendons & ligaments) 2) in the protective white layer of eyeball & deeper skin layers 4. Cartilage rigid connective tissue 1) matrix a) largely composed of collagenous fibers b) fibers embedded in gel-like ground substance 2) chondrocytes are cells a) lacunae small chambers within the matrix that the cells occupy b) chondrocytes do not divide frequently because of lack of blood supply 3) no direct blood supply a) perichondrium covering of connective tissue which encloses a cartilaginous structure i) contains blood vessels that provide cartilage with nutrients by diffusion b) lack of direct blood supply causes cartilage to heal slowly 1) provides support 2) frameworks & attachments 3) protects underlying tissues 4) forms structural models for developing bones c. Types of cartilage based on type of matrix (intercellular materials) 1) Hyaline cartilage - most common type a) matrix has very fine collagenous fibers; looks like white glass b) Locations i) ends of bones in joints ii) soft part of nose iii) supporting rings of respiratory passages 2) Elastic cartilage a) contains dense network of elastic fibers 3
b) more flexible than hyaline c) framework for ears & parts of larynx 3) Fibrocartilage a) very tough tissue with many collagenous fibers b) serves as a shock absorber for structures subjected to pressure (Ex. intervertebral disks, knees, & pelvic girdle) 5. Bone most rigid connective tissue 1) matrix is very hard a) due to mineral salts (calcium phosphate & calcium carbonate) between cells b) great deal of collagen which reinforces the minerals c) lamellae thin, concentric layers of bone matrix formed around central tube d) osteonic canals (Haversian canals) tubes in center of matrix e) lacunae pockets in matrix which house bone cells; are evenly spaced between lamellae 2) osteocytes mature bone cells a) located in lacunae b) in concentric circles because of spacing of lacunae c) canaliculi cytoplasmic processes of osteocytes 3) osteon (Haversian system) cylindrical unit made of osteonic canals with associated circles of lamellae & osteocytes 4) blood supply blood vessel in osteonic canals a) nourish bone cells b) canaliculi allow materials to pass easily between blood vessels & bone cells; allows bone to heal more quickly than cartilage 1) internally supports body structures 2) protects vital organs 3) attachment site for muscles 4) forms blood cells 5) stores & releases calcium & phosphorus 6. Blood - vascular tissue 1) Matrix is fluid called blood plasma 2) Formed elements cells of blood floating in plasma a) include red blood cells, white blood cells & platelets 1) transports materials between interior body cells & external environment 4
2) helps maintain stable internal environment II. Muscle Tissue A. General characteristics 1. contractile (can lengthen or shorten) 2. muscle fibers are muscle cells B. Three types 1. Skeletal muscle tissue muscle attached to bones a. voluntary b. striations alternating light & dark bands in cells c. multi-nucleated d. create movement of body 2. Smooth muscle tissue - comprises walls of hollow internal organs (ex. stomach, blood vessels, urinary bladder, etc.) a. not striated b. shorter than skeletal muscle fibers c. spindle-shaped d. one nucleus that is centrally located e. involuntary cannot be stimulated by conscious effort f. moves food through digestive tract, constricts blood vessels, & empties urinary bladder 3. Cardiac muscle tissue found only in the heart a. striated b. cells are end-to-end which results in branching & networks 1) intercalated disks specialized intercellular junction c. single nucleus d. involuntary e. pumps blood through the heart chambers III. Nervous Tissue found in brain, spinal cord, & nerves A. Structure 1. neurons cells of nervous tissue 2. cytoplasmic extensions of neurons connect neurons to each others and to muscles or glands 3. neuroglial cells- support cells of nervous system B. Functions 1. coordinate, regulate, & integrate many body functions 2. sensory reception V. Types of membranes four major types A. serous membranes line body cavities that lack opening to the outside of body 1. form inner linings of thorax ( parietal pleura) and abdomen (parietal peritoneum) 2. cover organs within cavities (visceral pleura & visceral peritoneum) 3. made of layers of a layer of simple squamous epithelium and thin layer of loose connective tissue 4. cells of membrane secrete serous fluid water secretion that lubricates membrane surfaces B. mucous membranes line cavities & tubes that open to the outside of the body 5
1. include oral & nasal cavities & tubes of digestive, respiratory, urinary, & reproductive systems 2. consists of epithelium overlying a layer of loose connective tissue 3. cells of membrane secrete mucus C. synovial membranes- form the inner linings of joint cavities between the ends of bones at freely movable joints (synovial joints) 1. consists of dense connective tissue overlying loose connective tissue & adipose 2. cells secrete synovial fluid a thick, colorless fluid which lubricates the ends of bone within the joint D. cutaneous membrane skin 6