6 Functions of Epithelial Tissue

1. protection
2. absorption
3. filtration
4. excretion
5. secretion
6. sensory reception

5 Special Characteristics of Epithelial Tissue

1. Polarity
2. Specialized contacts
3. Supported by connective tissue
4. Avascular but innervated
5. Regeneration

Polarity

tissue has two ends that differ in structure and function:

- apical surface (free; external)

- basal surface (attached surface; internal)

Specialized Contacts

Supported by connective tissue

Avascular but innervated

Regeneration

Basal lamina

Reticular lamina

Basement membrane

3 Cell Shapes

1. squamous - flattened puzzle pieces

2. cubodial - boxlike

3. columnar - tall

2 arrangements for epithelial tissue

1. simple - single layer of cells

2. stratified - 2 or more cell layers

Simple Squamous

structure: thin, flat, single layer

function: diffusion and filtration

location: heart, lungs, blood vessels, kidneys

Simple Cubodial

1. structure: single layer of cubed cells

2. function: absorption and secretion

3. location: kidneys and thyroid glands

Simple Columnar

1. structure: single layer of tall cells

2. function: absorption and secretion

3. location: depends...

         Ciliated                                              Nonciliated

- uterine tubes                                     - digestive tract (small

- bronchus (removes                             intestine contains

dust and carries it away                        microvilli)

from lungs)                                           - goblet cells (secrete                                                                    mucus - stomach & 

                                                                 large intestine)

Pseudostratified Columnar

1. structure: single layer of cells of differing heights - all touch basement membrane (typically ciliated)

2. function: secretion (mucus)

3. location: upper respiratory tract

Stratified Squamous

1. Structure: thick membrane composed of several layers

2. Function: PROTECTION!!

3. Location: depends...

  Keratinized                                           Nonkeratinized

- epidermis of skin                               - wet surfaces: mouth,

                                                                esophagus, tongue,

                                                                vagina

** regenerates

Transitional

1. structure - combo of stratified squamous and stratified cubodial

2. function - readily stretches

3. location - urinary bladder, uterers, uretha

Glands

Endocrine Glands

"internally secreting" glands that secrete hormones to the blood

ductless

ex: pituitary gland (growth hormone), adrenal gland (adrenaline)

Exocrine Glands

"externally secreting" glands that secrete their products to the body's surface or into body cavities

unicellular or multicellular

contain ducts

sebaceous (oil), sudoriferious (sweat), salivary, lacrimal, goblet cells (mucus), mammary

Goblet cells

Holocrine Glands

accumulate their products until they rupture

ex: oil glands

Merocrine Glands

all other types of secretion

ex: pancreas, sweat glands

4 Main Classes of Connective Tissue

1. connective tissue proper

2. cartilage

3. bone

4. blood

4 Functions of Connective Tissue

1. Binding and Support

(tendons, ligaments, cartilage)

2. Protection

(bones, connective tissue proper, cartilage)

3. Insulation

(adipose tissue)

4. Transportation

(blood)

Tendon

Ligament

connects bone to bone

3 Common Characteristics of Connective Tissue

1. Common origin -- all connective tissue arises from mesenchyme (embryonic tissue)

2. Degrees of vascularity -- amount of blood vessels/ blood supply

3. Extracellular matrix -- large amount; found outside the cell; contains ground substance and fibers

Blood Supply Scale

bone: a lot!

tendons & ligaments: small amount

cartilage: NONE!

Main Structural Elements of Connective Tissue

- ground substances

- collagen fibers

- cells

3 Basic Fibers

1. collagen

2. elastic

3. reticular

Collagen Fiber

made of protein

white

bundled, thickest, biggest

strongest!!

Elastic Fiber

made from elastin

yellow

stretches and rebounds

little branching

Reticular Fiber

made of collagen fibers

delicate network that surrounds small blood vessels and support the soft tissue of organs (spleen. lymph nodes)

lots of branching

function: support (like a fish net)

Cells found in connective tissue

• fibroblasts - makes fibers
  
• chrondoblasts - makes cartilage
  
• osteoblasts - makes bones
  
• hematopoietic stem cells - blood
  
• macrophage - engulf debri & particles
  
• mast cells - release & produce histamines (allergies)
  
• plasma cells - produce antibodies
  

mesenchyme

embryonic tissue that serves as the origin site for all connective tissue

Loose connective tissue proper

- adipose

- reticular

- areolar

Dense connective tissue proper

- dense regular

- dense irregular

- elastic

areolar connective tissue

contains all 3 types of fibers

*most abundant*

dense

used for packaging and filler for organs (packing peanuts)

adipose tissue

heat insulation, shock absorption, protection

cells close together

nucleus on side of cell

amitotic

fat found around kidneys, eye balls, and heart

Reticular connective tissue

SUPPORT!!!

location: reticular fibers, lymph nodes, bone marrow, spleen, liver

Dense  regular connective tissue

attaches muscles to bones and muscles to muscles

made up of collagen fibers

forms tendons and ligaments

fibers parallel to each other: strength in one direction

Dense Irregular Connective Tissue

provides structural strength

separates muscles groups

location: dermis of skin

made of collagen fibers

strength in all directions

Cartilage

tough but flexible

lacks nerve fibers and avascular

SUPPORT!!!

3 types: hyaline, elastic, fibrocartilage

Chondroblast

MAKES cartilage

Chondrocyte

(old cell) maintains cartilage

Hyaline Cartilage

made up of collagen

covers articular parts of long bones

makes of embryonic skeleton

* most abundant *

supports tip of nose, connects ribs to sternum, supports upper respiratory tract (trachea)

Elastic

made up of elastic fibers

maintains structure while allowing flexibitilty

supports external ear (epiglottis)

Fibrocartilage

made of collagen fibers

shock absorber

location: intervertebral disks, pubic symphysis, meniscus (knee joint)

Blood

transports respiratory gases, nutrients, wastes, and other substances

found in blood vessels

Covering and Lining Membranes of Connective Tissue

cutaneous

serous

mucous

Cutaneous Membrane

dry membrane exposed to air

location: skin

Mucous Membrane

protects and lubricates

lines hollow cavities that are open to the exterior

location: digestive, respiratory, urogenital