Histology The study of tissues.
Body Tissues Cells are specialized for particular functions Tissues Groups of cells with similar structure and function Four primary types Epithelium Connective tissue Nervous tissue Muscle Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.41
Epithelial Tissues Found in different areas Body coverings Body linings Glandular tissue Functions Protection Absorption Filtration Secretion Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.42
Epithelium Characteristics Cells fit closely together Tissue layer always has one free surface The lower surface is bound by a basement membrane Avascular (have no blood supply) Regenerate easily if well nourished Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.43
Classification of Epithelium Number of cell layers Simple one layer Stratified more than one layer Figure 3.16a Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.44a
Classification of Epithelium Shape of cells Squamous flattened Cuboidal cube-shaped Columnar column-like Figure 3.16b Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.44b
Simple Epithelium Simple squamous Single layer of flat cells Usually forms membranes Lines body cavities Lines lungs and capillaries Figure 3.17a Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.45
Simple Epithelium Simple cuboidal Single layer of cube-like cells Common in glands and their ducts Forms walls of kidney tubules Covers the ovaries Figure 3.17b Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.46
Simple Epithelium Simple columnar Single layer of tall cells Often includes goblet cells, which produce mucus Lines digestive tract Figure 3.17c Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.47
Simple Epithelium Pseudostratified Single layer, but some cells are shorter than others Often looks like a double cell layer Sometimes ciliated, such as in the respiratory tract May function in absorption or secretion Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.17d Slide 3.48
Stratified Epithelium Stratified squamous Cells at the free edge are flattened Found as a protective covering where friction is common Locations Skin Mouth Esophagus Figure 3.17e Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.49
Stratified Epithelium Stratified cuboidal Two layers of cuboidal cells Stratified columnar Surface cells are columnar, cells underneath vary in size and shape Stratified cuboidal and columnar Rare in human body Found mainly in ducts of large glands Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.50
Stratified Epithelium Transitional epithelium Shape of cells depends upon the amount of stretching Lines organs of the urinary system Figure 3.17f Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.51
Glandular Epithelium Gland one or more cells that secretes a particular product Two major gland types Endocrine gland Ductless Secretions are hormones Exocrine gland Empty through ducts to the epithelial surface Include sweat and oil glands Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.52
Found everywhere in the body Most abundant and widely distributed of all tissues
connects body parts binding & support protection insulation
Classes: -Connective tissue proper -Cartilage -Bone -Blood
1. Arise from mesenchyme (embryonic tissue) 2. Cover the whole range of vascularity - Cartilage = avascular - Dense Connective =poor vascularity - Other types=rich vascularity 3. Composed mainly of extracellular matrix (nonliving) 4. Have 3 main elements 1. Ground substance 2. Fibers 3. Cells
Unstructured material that fills the space between the cells & contains the fibers Holds large amounts of fluid (mostly water with adhesion proteins and polysaccharide molecules) Functions as a medium through which nutrients can diffuse between the capillaries and cells
- Produced by cells - Three types: 1. Collagen Fibers 2. Elastic Fibers 3. Reticular Fibers
Collagen Fibers (white fibers) - extremely tough - provide high tensile strength to the matrix
Elastic Fibers (yellow fibers) - long, thin, fibers that form branching networks in the extracellular matrix - found in skin, lungs, and blood vessel walls
Reticular Fibers - form delicate networks that surround small blood vessels and support tissue of organs
-Blood: Hematopoietic stem cell The primary blast (forming) cell types for each class: -Connective Tissue Proper: Fibroblast -Cartilage: Chondroblast -Bone: Osteoblast
5. Contains 3 common types of cells: Fibroblasts (most abundant) Macrophages -dispose of dead tissue cells, work in the immune system Mast Cells -prevents blood clots -initiate inflammatory response
1. Grab a packet 2. Get out 14 different colored writing utensils 3. Fill in the first 10 blanks of the packet using your notes or pages 127-130 in your book
Connective Tissue Proper- 2 subclasses A. Loose Connective Tissue 1. Areolar 2. Adipose 3. Reticular B. Dense Connective Tissue 1. Dense Regular (or Fibrous) 2. Dense Irregular 3. Elastic
Areolar Most widely distributed c.t in the body Serves as packing material between other tissues Support and bind other tissues Packages organs & surrounds capillaries Hold body fluids Defends against infection Stores nutrients When body area is inflamed, soaks up excess fluid = edema
Adipose (Fat) Similar to areolar tissue Located under skin, around kidneys & eyeballs, within abdomen, in breasts Fat tissue 18% of average person s body weight White fat or brown fat??? White fat stores nutrients/brown consumes its nutrient stores to generate heat to warm body brown fat is ONLY in babies (why?)
Reticular Fibers form a soft internal skeleton that supports other cell types (including white blood cells, mast cells, and macrophages) Located in lymphoid organs (lymph nodes, bone marrow, and spleen)
Dense Regular or Fibrous Closely packed Few cells Poor blood supply (slow healing) Found in Tendons connect muscles to bones Ligaments connect bones to bones
Dense Irregular Structurally similar to regular except collagen fibers are thicker and irregularly arranged. Found in body areas where tension is exerted from many different directions (dermis, surrounds organs)
Elastic Contain mostly elastic fibers Found in ligaments connecting adjacent vertebrae
Cartilage Stands up to tension & compression Lacks nerve fibers & is avascular Up to 80% water 3 types: Hyaline Elastic Fibrocartilage
Cartilage Hyaline gristle Most abundant/common Composed of an abundant amount of chondrocytes and a rubbery matrix End of long bones, nose, trachea, entire fetal skeleton
Cartilage Elastic Most flexible Composed of mostly elastic fibers and chondrocytes Found in the external ear, epiglottis, auditory tube, and some laryngeal and bronchiolar cartilages
Cartilage Fibrocartilage Very tough Mostly fibers and a few chondrocytes Found between the intervertebral discs, pubic symphysis, and menisci
Bone (Osseous Tissue) Composed of: Bone cells in lacunae (cavities) Hard matrix of calcium salts Large numbers of collagen fibers Haversian Canals (blood, nerves, loose c.t. Used to protect and support the body
Blood cells surrounded by fluid matrix = plasma Fibers are visible during clotting Functions as the transport vehicle for materials Red blood cells (erythrocytes) carry oxygen White blood cells (lymphocyte)- deal with tissue response to injury/illness Blood
Plasma cellsproduce antibodies
Muscle Tissue Function is to produce movement Three types Skeletal muscle Cardiac muscle Smooth muscle Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.64
Muscle Tissue Types Skeletal muscle Can be controlled voluntarily Cells attach to connective tissue Cells are striated Cells have more than one nucleus Figure 3.19b Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.65
Muscle Tissue Types Cardiac muscle Found only in the heart Function is to pump blood (involuntary) Cells attached to other cardiac muscle cells at intercalated discs Cells are striated One nucleus per cell Figure 3.19c Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.66
Muscle Tissue Types Smooth muscle Involuntary muscle Surrounds hollow organs Attached to other smooth muscle cells No visible striations One nucleus per cell Figure 3.19a Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.67
Nervous Tissue Neurons and nerve support cells Function is to send impulses to other areas of the body Irritability Conductivity Figure 3.20 Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.68
Tissue Repair Regeneration Replacement of destroyed tissue by the same kind of cells Fibrosis Repair by dense fibrous connective tissue (scar tissue) Determination of method Type of tissue damaged Severity of the injury Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.69
When tissue injury occurs, barriers are penetrated this stimulates the body s inflammatory and immune responses Tissue repair requires that cells divide and migrate, activities that are initiated by growth factors released by injured cells
Inflammation- tissue trauma causes injured tissue cells, macrophages, mast cells, and others to release inflammatory chemicals cause the capillaries to dilate and become very permeable walling off the injured area white blood cells and plasma fluid rich in clotting proteins, antibodies, and other substances seep into the injured area Platelets in the blood causes clotting
Organization- During organization, the blood clot is replaced by granulation tissue = scab Granulation tissue delicate pink tissue composed of several elements highly resistant to infection (produces bacteriainhabiting substances)
Regeneration and fibrosis effect permanent repair During organization, the surface regenerates New tissue grows under the scab which will soon detach. The end result is a fully regenerated primary layer Scar tissue lies underneath scarring.
Regeneration of Tissues Tissues that regenerate easily Epithelial tissue Fibrous connective tissue and bone Tissues that regenerate poorly Skeletal muscle Tissues that are replaced largely with scar tissue Cardiac muscle Nervous tissue within the brain and spinal cord Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.71
Developmental Aspects of Tissue 3 Primary germ layers: Endoderm Mesoderm Ectoderm Epithelial tissue arises from all three primary germ layers Muscle and connective tissue arise from the mesoderm Nervous tissue arises from the ectoderm By the end of the second month of development all primary tissues have appeared, and all organs are in place With old age there is a decrease in mass and viability in most tissues
Skin and Body Membranes Function of body membranes Line or cover body surfaces Protect body surfaces Lubricate body surfaces Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4.1
Classification of Body Membranes Epithelial membranes Cutaneous membrane Mucous membrane Serous membrane Connective tissue membranes Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4.2
Cutaneous Membrane Cutaneous membrane = skin A dry membrane Outermost protective boundary Superficial epidermis Keratinized stratified squamous epithelium Underlying dermis Mostly dense connective tissue Figure 4.1a Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4.3
Mucous Membranes Surface epithelium Type depends on site Underlying loose connective tissue (lamina propria) Lines all body cavities that open to the exterior body surface Often adapted for absorption or secretion Figure 4.1b Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4.4
Serous Membranes Surface simple squamous epithelium Underlying areolar connective tissue Lines open body cavities that are closed to the exterior of the body Serous layers separated by serous fluid Figure 4.1c Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 4.5
Serous Membranes Specific serous membranes Peritoneum Abdominal cavity Pleura Around the lungs Pericardium Around the heart Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 4.1d Slide 4.6
Connective Tissue Membrane Synovial membrane Connective tissue only Lines fibrous capsules surrounding joints Copyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 4.2 Slide 4.7