Tissues

Tissues Tissues are groups of similar cells with similar

structure that perform a similar function. Division of Labor

A. Epithelium = protect surfacesB. Muscular = ContractileC. Connective= support and hold parts together. (most common and diverse. Ex. Blood, fat)D. Nervous= irritable and conducts impulses

Epithelial Tissue Line and protect the external and

Internal body surfaces. Cells fit closely together and may

form layers. Tissue has two surfaces:

Apical surface faces the external environment.

Basal surface faces inner body tissues.

Epithelium is avascular, meaning it does not have a blood supply.

Cells regenerate quickly and easily

Epithelial Tissue Primary function is to protect against

bacterial and mechanical injury. Example: Serous fluid is secreted

whenever an area is damaged (appears swollen)

Classified by appearance into several different types.

Squamous Simple squamous cells are

single-layered, flat and irregular in shape (look like scales)

Cells are very thin to allow for substances to diffuse through them quickly.

Lining of blood vessels (capillaries), heart, lungs.

Simple Squamous Epithelia

Figure 3.18a

Stratified Squamous Epithelia

Multiple layers of cells; only the ones at the apical surface are flattened.

Rapidly dividing Provide protection in

areas of high friction (skin, esophagus)

Stratified Squamous Epithelia

Figure 3.18e

Simple Cuboidal

Single layer of cube-shaped cells.

Found in glands and the kidney.

Multiple golgi bodies within each cell.

Simple Cuboidal Epithelia

Figure 3.18b

Columnar

Rectangular-shaped cells; taller than they are wide.

Line the stomach and small intestines.

Specialized to secrete mucus (lubrication)

Simple Columnar Epithelia

Figure 3.18c

Pseudostratified Ciliated Columnar

Single layer of columnar cells.

Some cells are shorter than others, giving a double-layer appearance.

Usually contains cilia, or microscopic hairs capable of movement.

Aids in transport of material through trachea and intestines.

Help filter air in the nasal passages.

Pseudostratified Ciliated Columnar

Figure 3.18d

Connective Tissue

The most abundant and widely distributed type of tissue in the body.

Multiple functions: Holds body tissues together. Provides support to other cells and

tissues. Protection.

May be vascular or avascular.

Bone (osseus) Tissue

95% of bone is non-living calcium carbonate.

Osteoblasts- form bone Osteoclasts- break down

bone Reabsorbs and sculptures

bone. Recycle Calcium Osteoporosis= when

osteoclasts are more active than osteoblasts.

Bone (osseus) Tissue

Bone cells sit inside circular “pits” or lacunae surrounded by layers of calcium salts and collagen fibers.

Connective Tissue Types

Hyaline cartilage has a glassy blue-white appearance. Found in the larynx and joints between bones.

Connective Tissue Types

Fibrocartilage is more compressible and is found between the discs of the spinal cord.

Loose Connective

Loose connective tissues are softer and contain more cells and fewer fibers than other connective tissues.

Areolar tissue is the “cobwebby” tissue that cushions and protects body organs. Areolar tissue provides water and salts for surrounding cells. An edema is when the areolar tissue becomes fluid-filled.

Dense Connective

Dense connective tissue is primarily made of fibers of collagen protein.

This type of connective tissue is very strong and stretchable. Tendons – Attach skeletal muscles to bones. Ligaments – Attach bones to bones.

Adipose Tissue Fat

Reserve source of energy Cushioning, insulation Flotation

Reticular Tissue Network of irregular-shaped reticular cells and fibers that

serve as an internal framework for tissues that hold lots of red blood cells. Spleen Bone marrow

Blood Tissue Blood cells surrounded by plasma fluid. Red blood cells transport nutrients, waste,

oxygen, and carbon dioxide to each cell in the body.

White blood cells aid in protecting against foreign

Skeletal Muscle Tissue Multinucleate, striated, with a long cylindrical

shape. Under voluntary control. Contracts and pulls on bones and skin to

produce movements and facial expressions. Muscles do not undergo mitosis.

Exercise produces larger cells, not more cells.

Smooth Muscle

Involuntary Short fibers= slow contractions Found in the walls of hollow organs (especially

the digestive tract) No visible striations, one nucleus per cell.

Cardiac Muscle

Found only in the heart Cells are branched and form a network with other cells. Can contract independently without input from the central nervous

sytem. Cells are striated, contain one nucleus per cell, and have

intercalated disks at attachment points to other cells.

Nervous Tissue Conducts impulses to other areas of the body. Neurons are cells that send and receive

electrical and chemical stimuli. Nerve support cells provide nutrients and

other materials needed by neurons.