Chapter 5

Tissues

Tissues

• TISSUES: Organization or communities of similar cells often embedded in nonliving intracellular material called matrix.

• Histology - The study of tissues

Types of Tissue

• Epithelial• Connective• Muscle• Nervous

Appear within 2 months of fetal development.

Epithelial Tissue

• Epithelial - lack blood vessels (avascular), therefore they receive oxygen through diffusion.

• Function:– Protection - skin, mouth, stomach, etc.– Sensory - skin, nose, ears– Secretion - hormones, mucus, digestive

juices– Absorption - respiration, gut– Excretion - urine from kidneys

Structure of Epithelial Tissue

• Cells are tightly packed, little intracellular material.

• Always contains one free surface and one surface attached to a basement membrane = connective tissue.

• Membranous - thin tissue layer– Squamous - flat, platelike: blood vessels, alveoli– Columnar - narrow, cylindrical: uterine lining– Cuboidal - cubed shaped: glands– Simple - one layer of cells– Stratified - multiple layers of cells– Pseudostratified columnar - single layer of

cylinders of different heights

Simple Squamous

• Squamous – flat, platelike: blood vessels, alveoli

Simple Columnar

• Columnar – narrow, cylindrical: uterine lining

Simple Cuboidal

• Cuboidal – cubed shaped: glands

Stratified Squamous

• Stratified – multiple layers of cells

Pseudostratified Columnar

• Pseudostratified Columnar – single layer of cylinders at different heights

Structure of Epithelial Tissue Continued

•Glandular - specialized for secretion - function singularly or in clusters - exocrine – discharges secretions

into ducts that open onto surfaces like the skin and digestive tract (ex. tearducts)

- endocrine – discharges secretions into blood or tissue fluid. ex. Thyroid, pituitary

Classified according to the way they secrete their products. Types of exocrine glands: a. Merocrine – releases fluid by exocytosis

i. Serous cells in the linings ofthe body cavity

ii. Mucus cells in the liningsof the digestive and respiratorysystems.

Ex. Salivary glands, sweat glands,Pancreatic glands.

b. Apocrine – Lose small portions of their glandular cell bodies. Ex. Mammary glands.

c.Holocrine – entire cell released with fluidEx. Sebaceous glands in skin

Transitional Epithelium:

Note scalloped edges ofcells on free surface!

Specialized to changein response to increased tension. (Expandable)

•Found in inner lining of urinary bladderand lines the uretersand part of the urethra.

Transitional epithelium changes its appearance with stretching.  The epithelium on the left is relaxed and the cells appear stacked.   

On the right, the epithelium is stretched,the epithelial cells flatten and the overall epithelium becomes thinner.

http://www.nku.edu/~dempseyd/URINARY_1.htm

A. Simple

1. Simple squamous

2. Simple cuboidal

Basement membrane

3. a. Simple columnarb. Microvillic. Cilia - Ciliated columnar

4a. Glandular

4 b, c, Pseudostratified

B. Stratified5 a. Stratified squamous

6. Stratified cubodial

7a and b: Transitional

Connective Tissue

• Function• Attachment

– muscle to muscle– muscle to bone

• Support - organs and body as a whole.– produce blood cells – store fat– serve as framework

• Defense mechanism - fight against infection and repair tissue damage.

Connective Tissue

• Structure– Cells far apart– Have matrix (intercellular material-fluids,

fibers, etc…) between cells.

• Types– Adipose– Cartilage– Bone– Blood

Types of Connective Tissue

• Adipose – fat cells– Protective covering around organs– Insulation– Distribution is different in males and females– Stores energy

Types of Connective Tissue Continued

• Cartilage – dense fibrous– shock absorbers– heals very slowly (no direct blood

supply)– Types

a. Hyaline – most common, found on the ends of bone.

b. Elastic – more elastic, found on earsc. Fibrocartilage – tough tissue, pads

between disks in vertebrae.

Types of Connective Tissue Continued

Hyaline

Fibrocartilage

Elastic

Types of Connective Tissue Continued

• Bone– Specialized to form

blood– Allows attachment

for muscle

Types of Connective Tissue Continued

• Blood – liquid state– Oxygen movement– Red (transports

gases), white (fight infection), and platelet cells (blood clotting)

– Plasma = fluid portion– Defense against

bacteria– Ischemia = decrease

oxygen supply to organs

Muscle Tissue

• Function– Movement through contraction

• Types– Skeletal – Smooth– Cardiac

Muscle Tissue Continued

• Skeletal– Striated and voluntary– Muscles attached to bone– Controllable

Muscle Tissue Continued

• Smooth– Involuntary– Found in the walls of hollow internal organs

Muscle Tissue Continued

• Cardiac– Striated and involuntary– Only found in the heart

Nervous

• Function– Regulate and integrate communication

• Types– Neurons– Neuroglia

Nervous Continued

• Neurons – send and receive messages• Neuroglia – connect and support neurons

Nervous Continued• Structure

– Soma – body of neuron– Axon – carries impulses away from neuron– Dendrite – carries impulses to neuron