CHAPTER 4

 Study of different tissues  Abnormal cells and tissues can be compared to normal tissues to identify disease, such as cancer  Being able to know and recognize normal tissues under the microscope is the first step

 PRACTICE  There are thousands of images, virtual labs and practice quizzes online  DON’T MEMORIZE  Tissues from the same organ will look vastly different  RECOGNIZE PATTERNS  Don’t get lost in the big picture, look for patterns in how cells are organized  FORM = FUNCTION  Keep in mind the function of the tissue and the organ

 Tissues are collections of cells and cell products that perform specific, limited functions  Histology = study of tissues  There are 4 types of tissues 1. Epithelial – cover and protection 2. Connective - support 3. Muscle - movement 4. Neural – signaling and communication

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 Covers body surfaces and lines cavities  Forms most glands  Characteristics  Cells are tightly packed together  Free surface exposed to environment = APICAL SURFACE  Attached to underlying connective tissue (basement membrane)  Avascular (no blood supply) – nutrients must diffuse  Continually replaced at exposed surface

1. Protection from abrasion, dehydration, destruction 2. Regulate gas and nutrient exchange 3. Provide sensation 4. Secrete substances such as sweat, hormones, mucus and enzymes

1. First name indicates number of layers  Simple: one layer of cells  Stratified: more than one layer of cells  Pseudostratified: appears to be stratified but is not

2. Second name describes the shape of the cells  Squamous: thin and flat  Cuboidal: cube shaped  Columnar: tall, slender rectangles

1. Simple Squamous ▪ Description: single layer of flat cells ▪ Functions: passage of material by simple diffusion and filtration; secretes lubricating substances ▪ Location: alveoli of lungs

1. Simple Squamous Simple squamous lining the walls of the capillary

2. Simple Cuboidal ▪ Description: single layer of cube-shaped cells ▪ Functions: absorption and secretion ▪ Locations: Sweat glands, ducts, kidney tubules, thyroid gland

3. Simple columnar ▪ Description: single layer, tall cells ▪ Function: protection, absorption, secretion ▪ Locations: Lining of the nasal passages, stomach and intestines ▪ Other: : Cells are very long and often have cilia

4. Stratified Squamous ▪ Description: many layers of flat cells (look at the shape of the cells at the apical surface) ▪ Functions: Protection from abrasion, pathogens, and chemicals ▪ Locations: surface of skin, lining of mouth, throat, esophagus, rectum, anus and vagina

5. Pseudostratified ciliated columnar ▪ Description: single layer of columnar cells but the position of the nuclei make it appear as there are many layers; often ciliated ▪ Functions: Protection and secretion ▪ Locations: lining of nasal cavity, trachea and bronchi and portions of male reproductive tract

6. Transitional ▪ Description: transitions from one shape to the next; often has a scalloped apical edge ▪ Functions: permits expansion and recoil after stretching ▪ Locations: bladder, renal pelvis, ureters

Practice Identifying epithelial tissues Pseudostratified

Practice Identifying epithelial tissues Simple Squamous

Practice Identifying epithelial tissues Simple Cuboidal

Practice Identifying epithelial tissues Stratified Squamous

Practice Identifying epithelial tissues TRANSITIONAL

Practice Identifying epithelial tissues Simple Columnar

 Most diverse tissue of the body  Most abundant  Not as dense as epithelial tissue  Highly vascular  Composed of: 1. Cells 2. Protein Fibers (the matrix) 3. Ground Substance (extracellular components)

 Specialized cells  Mast cells (prevent blood clots)  Macrophages (phagocytic)  Fibroblasts (produce the tissue)  Protein fibers form the matrix  Collagen (thick)  Elastin (thin)

A. Collagen fibers B. Fibroblasts C. Mast cells D. Macrophages E. Elastic fibers F. Blood vessel/cells G. Fat cells

1. Support and protection 2. Transportation of materials 3. Storage of energy reserves (fat) 4. Fights infection, repairs tissue

1. Connective Tissue Proper a) Loose Connective b) Adipose c) Dense Connective 2. Cartilage a) Hyaline b) Elastic c) Fibrocartilage 3. Other Tissues a) Bone b) blood

1. Loose Connective Tissue (Areolar Tissue)  Structure: More ground substance, less fibers  Functions: cushion, support, movement, defense against pathogens  Locations: between other tissues and organs, beneath skin, digestive, respiratory and urinary tracts, between muscles, around blood vessels, nerves and joints

1. Loose Connective Tissue (Areolar Tissue)

2. Adipose (FAT)  Structure: Fibroblasts enlarge and store fat, very little matrix  Functions: stores energy, insulates and protects organs  Locations: beneath the skin and around organs especially at sides, buttocks, breasts, around eyes and kidneys

2. Adipose Tissue

3. Dense Regular (Fibrous)  Structure: tightly organized bundles of collagen  Functions: Tendons (connect muscles to bone) and Ligaments (connect bones to bones)

3. Dense Regular

 Gel-type ground substance  For shock absorption and protection  No blood vessels  Types of cartilage include  Hyaline cartilage  Elastic cartilage  Fibrous cartilage

1. Hyaline Cartilage  Most common  Very fine, white collagenous fibers  Covers ends of bones and joints and respiratory passages

2. Elastic Cartilage  Elastic fibers in addition to collagen  More flexible and elastic  External ear

3. Fibrous Cartilage (fibrocartilage)  Very tough, large numerous collagen fibers  Provides strong support and handles heavy pressure  Intervertebral discs

 Most rigid connective tissue  Rigid due to mineral salts  Bone cells called osteocytes  Periosteum (Covers bone surfaces)

HOMEWORK

 Physical barriers  Line internal spaces of organs and tubes that open to the outside  Line body cavities  Different types of membranes\  Mucous  Serous  Cutaneous  Synovial

 Mucous = protection  Line passages that have external connections  Lining of digestive, respiratory, urinary and reproductive tracts  Epithelial surfaces are moist to reduce friction and help absorption and excretion

 Line cavities not open to outside  Are thin but strong  Have fluid to reduce friction  Three serous membranes  Pleura – lungs  Peritoneum – abdomen  Pericardium - heart

 Outer covering of body  Skin  Thick, waterproof and dry  Stratified keratinized squamous epithelium

 Line freely movable joint cavities  Secrete synovial fluid into joint cavity – provides lubrication  Protects the end of bones  Lacks a true epithelium

 Specialized for contraction  Produces all body movement  Three types 1. Skeletal 2. Cardiac 3. Smooth

1. Skeletal Muscle  Voluntary  Cells are long, cylindrical, striated and multinucleate  Specialized for contraction

2. Cardiac Muscle  Involuntary  Cells are short, branched and striated usually with a single nucleus  Found only in the heart

3. Smooth muscle  Involuntary  Cells are short, spindle-shaped and non-striated with a single central nucleus  Walls of hollow, contracting organs (blood vessels digestive, respiratory, urinary and reproductive tracts)

 Specialized for conducting electrical impulses  Rapidly senses internal or external environment  Processes information and controls responses  Concentrated in the central nervous system  Brain and spinal cord  Two kinds of neural cells  Neurons = neurons  Neuroglia = supporting cells

 A.k.a nerve cells  Perform electrical communication  Parts of a neuron  Cell body – contains the nucleus  Dendrites – receive incoming signals  Axon (nerve fiber) – long thin extension of the cell body which carries outgoing electrical signals to the effector

 Supporting cells  Repair and supply nutrients to neurons

Tissues respond to injury to maintain homeostasis

 Inflammatory response  The tissue’s first response to injury  Signs and symptoms of the inflammatory response  Swelling, redness, heat, pain  Can be triggered by  Trauma (physical injury) or infection

 Fibroblasts produce dense network of collagen fibers (scar tissue)  Most successful in…  epithelia, connective tissues and smooth muscle  Least successful in…  Neural tissue, cardiac muscle

 Speed and efficiency of tissue repair decrease with age due to  Slower rate of energy consumption (metabolism)  Hormonal alterations  Reduced physical activity  Osteoporosis – age related reduction in bone strength of women

Tissue ID quizlet