Chapter 5 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 of the body cavity ii. Mucus cells in the linings of the digestive and respiratory systems. 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 fluid Ex. Sebaceous glands in skin

Transitional Epithelium: Note scalloped edges of cells on free surface! Specialized to change in response to increased tension. (Expandable) Found in inner lining of urinary bladder and lines the ureters and 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.

A. Simple 1. Simple squamous

2. Simple cuboidal Basement membrane

3. a. Simple columnar b. Microvilli c. Cilia - Ciliated columnar

4a. Glandular

4 b, c, Pseudostratified

B. Stratified 5 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 ears c.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