Histology Flashcards
What are the four primary tissue types?
Epithelial, Connective, Muscle and Nervous
Epithelial Tissue Characteristics
Lines the body surfaces and forms glands, cells fit closely together forming sheets, desmosomes and tight junctions hold adjacent cells together, apical and basal surface, avascular (no blood vessels), high capacity to regenerate
Apical surface
unattached, faces exterior or a lumen (space in the body)
Basal surface
attached, anchored to extracellular fibers (basil lamina)
Connective Tissue Characteristics
supports other tissues, specializes cells dispersed in non-living extracellular material, consists of matrix and ground substance
Matrix
Network of protein fibers surrounding cells in CT
Ground substance
Extracellular material that varies in consistency from thin liquid (plasma in blood), viscous liquid (maple syrup consistence in CT proper), gel (firm gel in cartilage), or solid (hydroxyapatite in bone). Structurally and functionally diverse.
What are the main categories of CT?
CT proper (includes stroma of soft organs, tendons and adipose), Supporting CT (includes bone and cartilage), Fluid CT (includes lymph and blood)
What are the major CT cell types?
Fibrocyte, Adipocyte, Erythrocyte, Leukocyte, Osteocyte, and Chondrocyte
Fibrocyte
Mature cells that maintain the matrix of CT proper
Adipocyte
Store fat in CT proper (abundant in adipose tissue)
Erythrocyte
Transport oxygen in blood, red blood cell
Leukocyte
Defend against infection, white blood cell
Osteocyte
Mature cells that maintain the matrix of bone
Chondrocyte
Mature cells that maintain the matrix of cartilage
Muscle Tissue Characteristics
Contract to produce motion, three main types are skeletal, smooth and cardiac muscle
Skeletal Muscle
Connected to bones through tendons
Smooth Muscle
Lines hollow organs
Cardiac Muscle
Forms wall of heart
Nervous Tissue Characteristics
Rapidly transmits and processes information, found in brain, spinal cord and nerves, contains specialized cells called neurons and neuroglia.
What are the four membrane type?
cutaneous, serous, mucous and synovial
Cutaneous Membrane
Cover the external surfaces of the body, keratinized stratified squamous epithelium, bound to underlying areolar CT, *epidermis and dermis
Mucous Membrane
Line cavities that open to the exterior, moist membrane, varies in epithelium bound to underlying areolar CT, *Respiratory, digestive and urinary
Serous Membrane
Line Ventral cavities that are closed to the exterior, simple squamous (mesothelium) on a thin layer of areolar CT, Parietal layer (lines cavity wall), Visceral layer (lines organ), serous fluid is secreted between the parietal and visceral layers *Examples include pleura (lines lungs), pericardium (lines heart), peritoneum (lines abdominal cavity and organs)
Synovial Membrane
Made up of CT no epithelium, lines inner surface of joint cavities, areolar CT only, Secrete synovial fluid for lubrication
What are the four stages of tissue healing after a wound?
Hemostasis, Inflammation, Granulation, Remodeling
Hemostasis
Clotting reduces blood loss fro damaged blood vessels, a network of fibrin protein traps blood cells and binds the edges together
Inflammation
Response of body to injury, works to increase the number of leukocytes in the tissue to defend against infection and remove damaged tissue *redness, swelling, heat, pain
Granulation
Fibroblasts from the surrounding CT fill in the wound with a network of extracellular fibers and blood vessels grow through forming granulation tissue, epithelial cells grow in from edges along the damaged surface
Remodeling
Fibers of CT are reorganized to maximize strength and minimize scarring *Regeneration- damaged tissue is replaced by same type of tissue (no scarring), epithelia, CT proper and bone regenerate easily or Fibrosis-damaged tissue is replaced by scar tissue (dense CT), cardiac muscle and nervous tissue does not regenerate and is replaced by scar tissue
Simple epithelium
one layer
Stratified
More than one layer
Pseudostratified
One layer that looks like two
Squamous
flattened
Cuboidal
Cube-shaped w=h
Columnar
Column-shaped h>w
Simple squamous epithelium
Function: diffusion and secretion
Location:Air sacs in lungs (alveoli), serous membranes that line body cavities, inner lining of blood vessels, portion of the nephron in kidneys
Simple cuboidal epithelium
Function: secretion and absorption
Location: Portion of the nephrons in kidneys, ducts of glands, follicles of thyroid
*central round nucleus
Simple columnar epithelium
Function: Absorption and secretion
Location: Lines digestive tract and uterine tubes
*oval nuclei, often contains goblet cells
Stratified squamous
Function: Protect underlying tissue from abrasion
Location: Skin, mouth, esophagus, rectum, vagina
Stratified cuboidal
Function: secretion
Location: Lines the ducts of sweat glands
Stratified columnar
Function: secretion
Location: Ducts of salivary glands
Pseudostratified columnar
Function: secretion and propel subtances (mucus) across cell surface
Location: Portion of respiratory tract (nasal cavity, larynx and trachea)
*contains goblet cells and cilia
Transitional Epithelium
Function: Stretches to permit distension to urinary organs
Location: lines ureters, urinary bladder and portions of kidney (renal pelvis)
*apical cells vary from cuboidal to squamous/basal cells appear cuboidal
Endocrine glands
expel secretions directly into surrounding tissue, diffuses into bloodstream, ductless, secrete hormones (thyroid, pituitary, adrenal glands)
Exocrine glands
Expel secretions onto a surface through a duct (goblet cells, sweat and oil glands in skin)
Simple exocrine gland
single unbranched duct
compound exocrine gland
branched duct
Tubular secretory portion of exocrine gland
elongated tube shpe
Alveolar (acinar) secretory portion of exocrine gland
expanded pocket or sac shape
Tubuloalveolar secretory portion of exocrine gland
combination of tube shape with an expanded end
What are the types of CT?
Areolar CT, adipose, reticular, dense regular, dense irregular and elastic CT
Areolar CT
loose CT proper, supports epitheleal tissues, space enables blood vessels to travel, matrix (fluid-gel w collagen fibers, reticular fibers and elastic fibers), various cells ( mesenchymal cells, fibroblasts, fibrocytes, adipocytes and leukocytes) *common under eipthelia in mucous and serous mebranes
Adipose CT
loose CT proper, closely packed adipocytes (fat cells), matrix (same as areolar CT), fat globules take up the cytoplasm pushing nucleus to the side, function: insulation, cushioning, fuel reserve *found under skin, around kidneys, abdomen, breasts
Reticular CT
loose CT proper, delicate network of interwoven reticular fibers, forms soft supportive skeleton for organs (stroma), found in spleen, lymph nodes, bone marrow and liver
Dense regular CT
CT proper w numerous parallel collagen fibers, matrix (parallel bundles of collagen fibers), fibroblasts and fibrocytes, resist unidirectional stress, found in tendons attaching muscle to bone and ligaments connecting bones
Dense irregular CT
CT proper with numerous collagen fibers running in different directions, Matrix (randomly arranged bundles of collagen fibers), fibroblasts, fibrocytes, resists multidirectional stress, found in deep dermis of the skin, joint capsules, fibrous capsules surrounding organs
Elastic CT
Dense CT proper, matrix (bundles of collagen fibers w numerous elastic fibers), resists stress, stretches, recoils, found in elastic arteries such as aorta and walls of blood vessels
What are the different types of supporting CT?
Hyaline cartilage, Elastic cartilage, Fibro cartilage and bone (osseous tissue)
Hyaline cartilage
most common type of cartilage, appears glassy and uniform, provide structure yet flexible, found in nose, ends of bones, costal cartilage, tracheal rings
Elastic cartilage
Similar to hyaline w numerous elastic fiber bundles, very flexible, able to tolerate repeated bending and maintain shape, found in external ear, eustachian tube and epiglottis
Fibro cartilage
Similar to hyaline w numerous collagen fibers, withstands heavy pressure and highly compressible, found in intervertebral discs, pubic symphysis and menisci
Bone or osseous tissue
Bundles of densely packed collagen fibers forming plates (lamellae) and struts (trabeculae), hard tissue provides structure for body and protection of organs, found in the skeleton
What are the types of fluid CT?
Blood and lymph
Blood
red liquid containing plasma, erythroctyes, leukocytes, and thrombocytes, transports material (oxygen), found within organs of the cardiovascular system (heart and blood vessels)
Lymph
Clear liquid containing leukocytes, drains extracellular fluid and transports materials (fat from intestines), found in lymphatic vessels and lymph nodes
