Histology Ms. Levensailor

Animal Tissues Hierarchy: cells  tissues  organs  organ systems Tissues: groups of cells with a common structure and function. Held together by : Sticky substance Woven together like a fabric From a Latin word meaning “weave” Note: Use the provided graphic organizer to take notes.

4 Main Categories Epithelial tissue Connective tissue Muscles tissue Nervous tissue With your face partner brainstorm the location and function of these tissue based on prior knowledge or their names.

Epithelial Tissue Cover the outside of the body and lines organs/cavities within the body. Closely joined/packed cells. Functions as a barrier against injury, invading organisms, fluid loss. Structure matches function!

Epithelial Tissue Free surface is exposed to air or fluid. Cells at the base of the barrier are attached to the basement membrane (dense layer of extracellular material). Criteria for Classification: Number of cell layers. Shape of the cells on the free surface.

Number of cell layers Simple: single layer of cells. Stratified: multiple tiers of cells.

Shape of Cells Cuboidal: like dice Columnar: like long bricks Squamous: like flat floor tiles

Put the words together. . .

Epithelial Tissue

Structure & Function Simple squamous: relatively leaky. Used for exchange of materials (diffusion) Linings of blood vessels and air sacs of the lungs. Stratified squamous: regenerates rapidly by cell division. Used as replacements for cells that are continually sloughed off. Outer skin linings like the esophagus.

Structure & Function Columnar epithelia: large cytoplasmic volume. Located where secretion or active absorption of substances are important. Stomach and intestines. Cuboidal cells: specialized for secretion. Kidney tubules, thyroid gland, and salivary glands.

Check for Understanding Grab a whiteboard and marker. What type of tissue is this? Simple squamous

Check for Understanding What type of tissue is this? Stratified squamous

Check for Understanding What type of tissue is this? Simple cuboidal

Check for Understanding What type of tissue is this? Stratified cuboidal

Check for Understanding What type of tissue is this? Simple columnar

Connective Tissue Function: to bind and support other tissues. Sparse population of cells scattered through an extracellular matrix. Matrix: nonliving, web of fibers embedded in a homogeneous substance (liquid, jelly, or solid). Secreted by the cells of the connective tissue.

Connective Tissue Major types: Loose connective tissue* Adipose tissue* Fibrous connective tissue Cartilage Bone* Blood *These will be our focus.

Loose Connective Tissue Used as: Binding to attach epithelia to underlying tissue. Packing material to hold organs in place. Made of a loose weave of fibers. 3 types of fibers: Collagenous Elastic Reticular

Loose Connective Tissue

Adipose Specialized connective tissue: stores fat in cells throughout the matrix. Functions: Pads and insulates the body. Stores fuel molecules. Cells contain large fat droplet that swells when fat is stored.

Bone Mineralized connective tissue. Cells called osteocytes: deposit a matrix of collagen & release calcium phosphate. Combination makes bone harder than cartilage without being brittle.

Check for Understanding What type of tissue is this? Loose Connective Tissue

Check for Understanding What type of tissue is this? Bone

Check for Understanding What type of tissue is this? Adipose

Muscle Tissue Composed of long excitable cells. Capable of contraction. Large numbers of microfilaments run parallel within cytoplasm of cells. Made of actin and myosin (contractile proteins).

Types of Tissue Skeletal Cardiac Visceral (smooth)

Skeletal Responsible for voluntary movements of the body. Adults have a fixed number of muscle cells. Weight lifting does not increase cell number, just enlarges cells. Also called striated muscle : overlapping microfilaments give the cells a striped appearance.

Cardiac Forms the contractile wall of the heart. Striated, but branched. Causes rhythmic beating and contractions of the heart (uncontrollable).

Visceral (smooth) Lacks cross-striations. Found in: Walls of the digestive tract, bladder, and arteries. Involuntary: not subject to conscious control.

Muscle Tissue Review

Check for Understanding What type of tissue is this? Smooth muscle

Check for Understanding What type of tissue is this? Cardiac muscle

Check for Understanding What type of tissue is this? Skeletal muscle

Nervous Tissue Senses stimuli and transmits signals. Functional unit is the neuron. Consists of: a cell body Nerve processes (two or more appendages) Dendrites: process impulses toward the cell body Axons: transmit impulses away from the cell body

Nervous Tissue