Animal Specialized Structures and Tissues

Study Notes

Tissues are formed from differentiated cells.
The human body consists of over 200 different types of cells.
Histology is the study of animal and plant tissues.
Four main tissue types in animals are epithelial, connective, muscle, and nervous.

Epithelial tissue can be simple (one layer) or stratified (multiple layers).
Simple epithelium is a single layer of cells.
Stratified epithelium has more than one layer of cells.
Types of epithelium include squamous (flat), cuboidal (cube-shaped), and columnar (column-shaped).

Connective tissues are characterized by a large extracellular matrix.
The extracellular matrix can be solid, soft, or liquid. Examples include bone, soft connective tissue, and blood.
The primary function of connective tissues is to bind and support other tissues.
Connective Tissues are classified into three groups: connective tissue proper, supportive connective tissue, and fluid connective tissue.
Connective tissue proper includes loose, dense, reticular, and adipose connective tissues.
Loose connective tissue (also called areolar) has a watery matrix where fibroblasts and other cells reside.
Dense connective tissue is made of closely packed bundles of collagen fibers.
Reticular connective tissue is composed of reticular cells and fibers, providing support for soft organs.
Elastic connective tissue is highly flexible and contains elastic fibers and collagen fibers.
Adipose tissue is a specialized connective tissue that stores fat.
Supportive connective tissue includes cartilage and bone.
Cartilage contains chondrocytes in a matrix of chrondrin.
Bone contains osteocytes in a mineralized matrix with collagen fibers.
Fluid connective tissue includes blood.
Blood is a fluid connective tissue with a liquid matrix (plasma).
Blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

Muscle tissues are contractile tissues that enable movement.
Muscle tissues contain muscle fibers.
Three types of muscle tissue are skeletal, cardiac, and smooth.
Skeletal muscle tissues attach to bones and are responsible for locomotion. Their contractions are voluntary.
Cardiac muscle tissue is found only in the heart and pumps blood. Its contractions are involuntary.
Smooth muscle tissue is found in the walls of internal organs and blood vessels and are involuntary.

Vegetative organs include roots, stems, and leaves.
Roots anchor plants to the soil and absorb water and minerals.
Stems are the main axis of the plant and distribute the products of photosynthesis.
Leaves carry out photosynthesis to produce food.

Two main types of plant tissues are meristematic and permanent.
Meristematic tissue is responsible for plant growth.
Meristems are embryonic tissues made of meristematic cells.
Meristems are found in areas of fastest growth.
Permanent tissues are created from meristem tissues
Permanent tissues are further divided into three classes: surface, fundamental, and vascular.
Surface tissues (also called dermal tissues) cover and protect plant organs. The epidermis is an example of a surface tissue.
Fundamental tissues (also called ground tissues) form the main bulk of the plant.
Fundamental tissues are composed of three types of cells: parenchyma, collenchyma, and sclerenchyma.
Parenchyma cells are large, thin-walled, and are responsible for food storage and are also capable of cell division.
Collenchyma cells function primarily for support. They are similar to parenchymal cells, but have thicker cell walls.
Sclerenchyma cells have a thick secondary cell wall made of lignin, providing support and strength.
Vascular tissues (xylem and phloem) are complex conducting tissues in plants and extend to all parts of the plant.
Xylem transports water and minerals from roots to shoots.
Phloem transports sugars and other organic nutrients throughout the plant. Phloem often sits outside of xylem.