Animal Tissues

Animal Tissues

Prepared by:Maricar B. Macalam, MOB

Cells form groups to produce specialized tissues that function together in a specific activity

Classification: Epithelial tissues Connective tissues Muscular tissue Nervous tissues

Animal Tissues

 serve as protective layers and/or secretory components of body organs and systems

Epithelial Characteristics◦ Limited intercellular space – specialized intercellular junctions hold

the membranes of epithelial cells tightly together --- results in restricted intercellular space between cells --- enables epithelial cells to control substances that pass from one side of the cell to the other --- in this way epithelia serve in absorptive, secretory, & excretory functions

◦ Single or multiple layers of cells - consist of a single cohesive layer or multiple layers of cells cemented together

◦ Free apical surfaces -  where secretion, absorption, & excretion functions occur.  Opposite to the apical surface is the basal surface that attaches to underlying tissues via a specialized basement membrane resting on connective tissues

◦ Avascular -  lack blood vessels --- Nutrient delivery to, and waste elimination from epithelia are always functions of blood vessels found in nearby connective tissues

◦ Mitotic capability - (the ability to divide and form new cells) enables epithelial cells to engage in repair and regenerative activities

Epithelial Tissues

a. Cell shapes: squamous, cuboidal, or columnarb. Number of cell layers: simple or stratifiedc. Surface modifications

Cilia and stereocilia are similar filament-like structures projecting from the apical cell surfaces o cilia act as an important cleansing mechanism for the

respiratory tracto cilia act in directing released eggs into the fallopian tubes

and moving these to the uteruso Stereocilia appear to have nutritive/supportive roles in the

male reproductive tract or sensory functions in the special senses

microvilli are shorter and more uniform in length projecting from the apical cell surfaces --- form the "brush border" of the small intestine where most absorption in our bodies occurs

Classification of Epithelia

consist of dispersed cells that typically lack intercellular contact

extracellular spaces (extracellular matrix) in connective tissues are more abundant and contain vessels

vascularized with the single exception being cartilage

classification:

Connective tissues

Connective Tissue Category Tissue Types

1. Fluid Connective Tissues Blood and Lymph

2. Connective Tissues Proper Loose and Dense CTs

3. Supportive Connective Tissues Cartilage and Bone

form the structural framework for the body (bone, cartilage)

transport nutrients and wastes (blood) provide protection for vital organs (bone,

cartilage, adipose tissue) provide support and interconnection

(tendons, ligaments, capsules) insulate, store energy and produce

important cells of blood and lymphatic tissues (adipose tissue, bone marrow)

contribute to body defense and repair (blood, lymph, dense CT)

Functions of connective tissues

consists of protein fibers & ground substance (GS) the GS is a mix of mucopolysaccharides, glycoproteins,

minerals, and other substances◦ Physically it is a fluid in CTs proper, blood, and lymph◦ In cartilages, GSs are a durable but flexible gelatinous solid◦ In bone, GS is a crystalline solid◦ it include1. hyaluronic acid - forms the viscous fluid of CTs proper2. chondroitin sulfate - forms the gelatinous material of cartilage3. hydroxyapatite - forms the solid, crystalline matrix of bone

protein fibers embedded in the GS of the various CTs provide strength, support, and elasticity1. collagen - very strong, flexible, inelastic fibers made from the

protein collagen2. elastic - strong but stretchable fibers made of the protein

elastin3. reticular - small branching collagen fibers that form a reticulum

or network to support cells

Extracellular Matrix

Loose CT - fibers are smaller and arranged in loose, random arrays possesses randomly arranged protein fibers with abundant intercellular spaces.

 Scattered within the spaces are 7 cell types1. fibroblasts - elongate, flattened cells that form the protein fibers and

ground substance2. macrophages  or histiocytes - amoeboid or fixed phagocytic cells derived

from monocytes of the blood.  Macrophages play a role in phagocytosis (non-specific body defense) and thereafter enter the lymphatic system to aid in activation of immune responses (specific body defense) as antigen-presenting cells (APCs)

3. Leukocytes - these blood borne defensive cells leave the vascular system during inflammatory events to patrol adjoining tissue spaces.  Most are neutrophils or lymphocytes

4. plasma cells - are lymphatic cells derived from B-lymphocytes.  Plasma cells are highly efficient producers of antibodies.  Although most are located in lymphatic tissues like lymph nodes, they do occur in loose c.t. areas

5. mast cells - this is the key cell involved in inflammation. Mast cells release histamine and heparin. These chemical agents induce the vascular responses that cause inflammation

6. Adipocytes - are the cells involved in the metabolism and storage of fats or triglycerides

7. mesenchymal cells - these are the embryonic stem cells that divide to form new cells of all connective tissue types

Three types of loose CT:  areolar, adipose, and reticular types

Chondrocytes (cartilage cells) Avascular,  lacking blood vessels ---- does not

possess the regenerative capacity contains a gelatinous ground substance called

chondroitin sulfate◦ Embedded within the GS are collagen & elastic fibers◦ Together (chondroitin sulfate + fibers) -- flexible, yet very

durable and also resistant to compression forces produced by chondroblasts through the process

chondrification Typesa. Hyaline cartilage – most common type; in fetal

skeleton, cartilaginous fishesb. Elastic cartilagec. Fibrocartilage

Cartilage

Osteocytes – bone cells Produced by osteoblast in the process called

ossification The matrix of bone contains abundant collagen fibers

--- impart strength & resistance to twisting or torsional forces --- surrounded by a a cement-like ground substance called hydroxyapatite

Together (collagen fibers+hydroxyapatite) make bone one of the strongest and lightest materials known

Functions:◦ support - for muscles, organs, and soft tissues◦ leverage and movement - the synovial joints◦ protection - for critical organs◦ calcium phosphate storage - mineral balance◦ hemopoiesis - formation of blood cells

Osseous tissue or bone

Blood

are specialized for contraction. Muscle cells possess◦ Contractility◦ Excitability (able to respond to stimuli) ◦ Extensibility (can be stretched and still maintain contractile

ability) ◦ Elasticity (enable muscles to contract or stretch and then

return to their original length) Functions

◦ support and movement◦ propulsion of blood through vessels◦ movement of food or body secretions through tracts◦ thermoregulation

Muscle cells or myofibers are of three types ◦ Skeletal◦ Smooth◦ Cardiac

Muscle Tissue

Muscular tissues

Charateristics Skeletal Smooth Cardiac

Location Attached to skeleton

Walls of internal organs

Walls of heart

Cross-striations Present Absent Present

Shape of fibers Cylindrical Spindle-shaped

Branched

Number of nuclei

Many or multinucleate

One or uninucleate

One or uninucleate

Position of nuclei

Peripheral Center Center

Type of control Voluntary Involuntary Involuntary

Speed of contraction

Most rapid slowest Intermediate

Neuron◦ Cell body◦ Processes

a. Axonb. Dendrites

Nervous tissues

Nervous tissue consists of neurons, which are the cells that conduct signals, and supporting neuroglial cells such as microglial cells, astrocytes and oligodendrocytes

-The End – Thank you for listening