E3 Chapter 5: Tisses

nervous tissue

composed of 2 general types of cells: 1) neurons: transmit nerve impulses 2) neuroglial cells: supporting cells

appositional growth

(1/2 ways cartilage grows) -new layers of cartilage are added to the surface of the already existing cartilage -fibroblasts in the cellular layer of the perichondrium divide -the innermost cells differentiate into immature chondrocytes called CHONDROBLASTS and produce more cartilage matrix -the CHONDROBLASTS become surrounded by and embedded in the new matrix and differentiate into mature chondrocytes (APPOSITIONAL = APP = APPLYING new layer of cartilage onto older layer of cartilage) -MAY occur after adolescence if: 1) there is excessive stimulation by growth hormone from the pituitary gland 2) there is MINOR damage to the cartilage ---severe damage would result in the formation of scar tissue to replace damaged cartilage

cartilage

(1/3 types of specialized connective tissue) -more rigid than dense connective tissue but more flexible than bone -found in joints where it forms a layer over the bone -prevents the sensitive outer layers of bone from rubbing against each other as the joint moves -found in: ears, nose, vocal cords, and the embryo (acts as a framework upon which the bony skeleton is formed)

interstitial growth

(2/2 ways cartilage grows) -a chondrocyte within its lacuna divides to produce 2 cells -each daughter cell secretes more matrix which pushes the cells apart and adds to the cartilage from within -cartilage grows from fetal development through adolescence -in mature adult animals, there is neither interstitial nor appositional growth

bone

(2/3 types of specialized connective tissue) -hardest and most rigid type of connective tissue -specialized matrix contains both organic collagen fibers & inorganic calcium salts ----the calcium salts alone (like calcium carbonate & calcium phosphate) would make the bone brittle but by combining them with the collagen fibers, the bone gains flexibility and strength -bone is well vascularized (has a lot of blood vessels)

blood

(3/3 types of specialized connective tissue) -MATRIX is the liquid portion of the blood or PLASMA -the fibrous component of the matrix is an array of protein molecules suspended in solution -the protein molecules are only visible when blood clots -blood contains many different types of cells

serous membranes

(a type of epithelial membrane) -normally the amount of serous fluid is quite small -in pathologic conditions, the amount of fluid may increase and become excessive -if the serous membranes are damaged, the amount of fluid may decrease and abnormal connections may form between the parietal and visceral layers -in the abdominopelvic cavity, double sheets of peritoneal membrane form where the visceral peritoneum and parietal peritoneum connect ---this forms supportive ligaments called MESENTERIES

hyaline cartilage

(a type of specialized connective tissue) (1/3 cartilage types) -the most rigid cartilage type -tough but more flexible than bone -enclosed w/ a perichondrium -composed of closely packed COLLAGEN FIBERS -found: articular cartilage at the ends of long bones, connects the ribs to the sternum, forms the rings in the trachea, the growth plates of growing animals, makes up most of the skeleton in the embryo

elastic cartilage

(a type of specialized connective tissue) (2/3 cartilage types) -similar to hyaline but contains many elastic fibers that give the cartilage a lot of flexibility so it can bend repeatedly -found: epiglottis of the larynx and the pinna of the ear

fibrocartilage

(a type of specialized connective tissue) (3/3 cartilage types) -usually found merged with cartilage and dense connective tissue -contains bundles of collagen fibers like hyaline cartilage but has fewer chondrocytes and doesn't have a perichondrium -well designed to withstand compression -found: between the vertebrae, between the bones that form the pelvis, in the stifle joint

process of inflammation: macrophages & neutrophils

-2 types of phagocytic cells move into the area 1) macrophages 2) neutrophils: a type of white blood cell that squeezes through the walls of the dilated capillaries to leave the blood and enter the tissues -phagocytic cells help destroy microorganisms and remove debris -the cells only function for a few hours before dying and forming PUS as they collect in the injured area

regeneration & fibrosis

-REGENERATION: a replacement of destroyed tissue by the same kind of tissue -FIBROSIS: involves the formation of FIBROUS CONNECTIVE TISSUE/SCAR TISSUE -some wounds heal by regeneration, others heal by fibrosis, and others heal by both

process of inflammation: clot

-a clot begins to form at the injured area...this: 1) slows the bleeding 2) isolates the wound from invading pathogens 3) prevents any microorganisms or toxins in the wound from spreading to surrounding tissues -clots that form on external surfaces dry out and are called SCABS

composition of serous membranes

-a sheet of simple squamous epithelium bound to an underlying layer of loose connective tissue -interstitial fluid passes through the serous membranes into the space between the 2 layers -it is enriched by hylauronic acid from a TRANSUDATE ---normal serous fluid is a transudate. -serous fluid is thin and watery and creates a moist, slippery surface on the parietal & visceral layers

transudate

-a thin, watery fluid that has passed through a membrane -contains little if any protein

evaluating the mucuous membranes

-an examination of the mucuous membranes should be part of every p.e. -abnormalities of the mucuous membranes can give important clues about an animal's illness -the easiest area to examine is the gingiva of the conjunctiva of the eye -the 3 characteristics we look for: 1) color 2) capillary refill time CRT 3) hydration

formation of granulation tissue

-as inflammation proceeds and macrophages work to clean up debris, a new tissue called GRANULATION TISSUE forms beneath the overlying blood clot or scab -fibroblasts produce 2 things in granulation tissue: 1) growth factors 2) collagen fibers

process of inflammation: vasoconstriction/vasodilation

-begins with 5-10 minute period of VASOCONSTRICTION followed by prolonged period of VASODILATION -vasoconstriction: helps control bleeding at the injured site -MAST CELLS in the area release HISTAMINE & HEPARIN ---effects: 1) causes vasodilation: results in increased blood flow to the area. Causes heat & redness. Increases the supply of oxygen & nutrients to active cells. Increases removal of waste products 2) increases the permeability of the capillaries. Allows fluid from the plasma to leak into the area. Fluid contains enzymes, antibodies and proteins. Causes swelling of soft tissues. Swelling irritates delicate nerve endings and causes pain and tenderness

characteristics of membranes

-composed of an epithelium bound to an underlying layer of connective tissue proper -functions: 1) line body cavities 2) separate organs 3) cover surfaces -epithelium is usually bathed in a wet solution: 1) mucus 2) transudate 3) urine (in the bladder)

skeletal muscle

-contractions are consciously controlled so it is called VOLUNTARY MUSCLE -large and contain hundreds of nuclei and mitochondria -appears to be striped under a microscope because of hundreds of alternating light & dark bands ---said to be STRIATED -skeletal muscle fibrils are clustered together into bundles to form skeletal muscle cells (muscle fibers) -the bundles of fibrils are held together by loose connective tissue -collagen fibers surround the cells and merge with the collagen fibers in tendons ---the tendons attach muscles to bones -muscle fibers are stimulated to contract by nerve fibers located throughout the muscle and attaching to the cells -if the nerves are damaged, the muscle will not be able to contract normally

cardiac muscle

-contractions are not consciously controlled -special pacemaker cells within the heart muscle signal the heart to contract at regular intervals -cells are small and contain 1 nucleus -cells are striated -cells branch and connect to other cardiac cells by a specialized intercellular junction called an INTERCALATED DISCS -intercalated discs: combination of desmosomes and gap junctions -through these interconnections, cardiac muscle cells form a branching network

smooth muscle

-contractions are not consciously controlled so smooth muscle is also called involuntary muscle -cells are small, spindle shaped and have 1 nucleus

epithelial tissues

-during organization the surface epithelium begins to regenerate -epithelial tissues around the edges of the wound begin to divide and lay down a new layer of epithelial tissue over the granulation tissue and UNDER the scab ---the scab detaches and falls off -the epithelium has regenerated and there is an underlying area of scar tissue formed as the granulation tissue is replaced by scar tissue -as the scar tissue contracts, it helps to pull the wound closer

layers of mucuous membranes

-epithelial layer rests of LAMINA PROPRIA -LAMINA PROPRIA: loose connective tissue -beneath the LAMINA PROPRIA is another layer of connective tissue called: submucosa ----submucosa usually connects mucuous to underlying structures

evaluating the mucuous membranes: Capillary Refill Time

-evaluated by pressing on the mucuous membranes so it turns white and timing how long it takes to turn pink again -normal CRT is 1-2 seconds -indicates how well supplied with blood the tissues are -the longer the CRT, the poorer the tissue supply

collagen fibers

-granulation tissue is composed of collagen fibers (produced by fibroblasts) and small capillaries that have grown in from nearby tissues -the capillaries push up into the bed of collagen fibers and give the tissue a "granular appearance"

evaluating the mucuous membranes: hydration

-normally the mucuous membranes should be moist -if the mucuous membranes are dry or tacky it would indicate dehydration

process of inflammation: histamine & heparin

-levels of histamine & heparin decrease -blood vessel size and capillary permeability return to normal -fluid leakage decreases -blood flow decreases -swelling, heat and redness decrease

synovial membranes

-line the cavities of joints -have no epithelium -composed entirely of connective tissue

functions & characteristics of mucuous membranes

-mucus secretions: 1) urinary doesn't secrete mucus 2) digestive and respiratory tracts secrete large amounts of mucus ---mucus may come from GOBLET CELLS or multi-cellular glands found throughout the tissues -mucus contains: 1) mucin: a protein 2) water 3) electrolytes 4) antibodies -functions: 1) decreases friction which helps in the passage of food, wastes 2) antibodies and viscosity help trap and dispose of microorganisms -some mucuous membranes have absorptive functions: digestive tract

inflammation

-non-specific response to injury or disease -does not mean an area is infected -INFECTION is inflammation caused by viruses, bacteria, fungi -can be caused by: 1) burns 2) broken bones 3) pulled muscles -signs: 1) redness 2) swelling 3) heat 4) pain

composition of cutaneous membranes/integument

-outer layer is keratinized stratified squamous epithelium called epidermis -as the cells migrate from the basement membrane to the outermost layer, keratin fills the cells -keratin is a waxy, waterproof substance -keratin waterproofs the skin to protect and prevent desiccation and help skin withstand abrasive forces -underlying layer is dense irregular connective tissue called the dermis

third intention

-same as 2nd intention but healing occurs more slowly and the wounds are extensive (gap between the edges is wider)

functions of mesenteries

-secure organs to the body wall -form an access route for blood vessels and nerves to pass to and from the digestive tract ex) 1) stomach is connected to the abdominal wall by mesentery called the OMENTUM 2) uterus is attached to abdominal wall by mesentery called the BROAD LIGAMENT

layers of serous membranes

-serous membranes form a continuous sheet that folds over on itself to form 2 layers with a narrow space between them -PARITEAL LAYER: the part of the membrane that lines the cavity wall -VISCERAL LAYER: the part of the membrane that covers the outer surface of the organ -serous membranes are very thin but are firmly attached to the body wall and the organs they cover -when you can see an organ like the heart or stomach, you are seeing the tissues of the organs through a transparent serous membrane

scar tissue or similar tissue replacement

-when epithelialization is complete the scar may or may not be visible -depends on the severity of the injury and the extent of scar formation -tissues that regenerate well will replace the damaged tissue with similar tissue -the poorer the tissue's ability to regenerate, the more scar tissue will be formed to replace damaged tissues

tissues healing & repair

-the body's first response to injury is inflammation -inflammation helps to limit further injury and eliminate harmful agents -repair occurs more slowly and involves: 1) organization of granulation tissues 2) regeneration of lost tissue and/or the formation of scar tissue (fibrous connective tissue)

first intention

-the edges of the wound are held closely together -tissue forms a primary union -no formation of granulation tissue (becomes scar tissue) -no significant scarring

second intention

-the edges of the wound are separated -granulation tissue forms close to the gap -there is scar tissue formation

there are 3 types of healing

1) 1st intention 2) 2nd intention 3) 3rd intention

where are serous membranes found?

-they line the walls and cover the organs that fill CLOSED body cavities

characteristics of granulation tissue

-tissue is very resistant to infection because it produces bacteria inhibiting substances -because it is very vascular, this tissue bleeds easily -does NOT contain nerve endings -sometimes this tissue becomes too thick and stands out above the epithelial layer (PROUD FLESH) ---may need to be cut away to facilitate closure of epithelial layer ---this is done easily since there are no nerve endings -proud flesh is commonly seen in horses with skin wounds -granulation tissue is replaced by FIBROUS SCAR TISSUE as the fibroblasts make more collagen fibers and ground substance -scar tissue replaces lost tissue and bridges the wound -some fibroblasts have contractile properties that will help pull the edges of a wound together

function of serous membranes

-to minimize the friction between opposing parietal & visceral surfaces

scar tissue

-very strong -lacks flexibility -contracts down over time -cannot preform functions of damaged tissues -as it contracts down, it becomes less visible but may constrict a hollow organ like the esophagus -it may form adhesions that connect tissues that are not meant to be connected

evaluating the mucuous membranes: color

1) JAUNDICE/ICTERUS: there is an excessive amount of bilirubin in the blood ---indicated by a yellow tinge to the mucuous membranes 2) CYANOSIS: a bluish color to the mucuous membranes indicates HYPOXIA: less than a normal amount of oxygen in the blood 3) HYPERMIA: a bright red color to the mucuous membranes indicates there is more than the normal amount of blood in the blood vessels 4) PALE MUCUOUS MEMBRANES: indicates less than a normal amount of blood or red blood cells in the blood vessels

3 types of specialized connective tissue

1) cartilage 2) bone 3) blood

composition of cartilage

1) cells (chrondrocytes) live in hollowed out pockets (chambers, cavities) within the matrix called LACUNAE 2) MATRIX or GROUND SUBSTANCE is a firm gel that contains: 2 glycosaminoglycans: 1) chondroitin sulfate 2) hyaluronic acid -an adhesion protein called CONDRONECTIN -a large amount of water (80%) ---important in transporting nutrients to the chondrocytes ---gives cartilage flexibility, resilience, an ability to withstand compression ---particularly important in joints 3) fibers -collagen fibers -elastic fibers

3 types of cartilage

1) hyaline 2) elastic 3) fibrocartilage

scar tissue vs. regeneration: how to control

1) keep inserting something to stretch tissues 2) laser: surgically removes scar tissue

wound healing; classified by

1) mechanism of healing 2) proximity of wound edges

4 common types of epithelial membranes:

1) mucuous membranes 2) serous membranes 3) cutaneous membranes 4) synovial membranes

3 types of serous membranes

1) pleua: lines the pleural cavity and covers the lungs 2) peritoneum: lines the peritoneal cavity and covers the lungs 3) pericardium: lines the pericardial cavity and covers the heart

3 types of muscle tissue

1) skeletal 2) smooth 3) cardiac

cartilage grows in 2 ways

appositional growth interstitial growth

characteristics of cartilage

avascular -lack of nerves allows it to stand a lot of compression w/o pain -lack of blood vessels means it is very slow to heal

tissues with little/no capacity to regenerate

cardiac muscle nervous tissue in brain nervous tissue in spinal cord

nutrition: cartilage

cartilage receives its nutrition from the PERICHONDRIUM: a layer of tissue that surrounds the cartilage ---contains many blood vessels -nutrients diffuse from the perichondrium, through the matrix, to the chondrocytes ---the chondrocytes furthest away from the perichondrium could be less well nourished than the chondrocytes close to the perichondrium if the cartilage became too thick ------------b/c of this, the thickness of the cartilage is limited

tissues that regenerate well

epithelial bone aerolar connective tissue dense irregular connective tissue blood forming tissues

where are mucuous membranes found?

found lining areas that are EXPOSED TO or CONNECTED to the OUTSIDE environment -found: digestive tract (mouth, anus, esophagus, stomach), respiratory tract (nasal passages and trachea), bladder & uterus, mucuous membranes of the eye

composition of synovial membranes

loose connective tissue and adipose tissue covered by a layer of collagen fibers and fibroblasts -synovial membranes make synovial fluid that fills the joint cavity

tissues with weak capacity to regenerate

skeletal muscle cartilage

tissues with moderate capacity to regenerate

smooth muscle dense muscle tissue

function of synovial membanes

synovial fluid and hyaline cartilage decrease friction and abrasion at the ends of bones