Epithelial Tissue Types

• Lab Exercises 7 & 8 cover various tissue types including epithelial, connective, muscle, and nervous tissue.

Epithelial Tissue

Simple Squamous Epithelium (Kidney)

• Appearance: Thin, single layer with flattened oval nuclei.
• Location: Inner layer of vessels, some membranes, alveoli, and glomerular capsules.
• Function: Diffusion, filtration, and acting as a barrier.

Simple Cuboidal Epithelium (Kidney)

• Appearance: Square-ish, single layer with rounded nuclei.
• Location: Nephron tubules, glands, and ducts.
• Function: Secretion and absorption.

Simple Columnar Epithelium (Intestine)

• Appearance: Column-shaped, single layer with elongated nuclei and goblet cells; may have cilia or microvilli.
• Location: Gastrointestinal tract, uterine tubes, ventricles.
• Function: Secretion and absorption.

Stratified Squamous Epithelium (Esophagus)

• Appearance: Thin upper layer(s) of squamous cells and multiple lower levels of cuboidal/columnar cells.
• Location: Epidermis and upper gastrointestinal tract.
• Function: Protection from abrasion and infections.

Pseudostratified Columnar Epithelium (Trachea)

• Appearance: Tightly packed columnar epithelium in a single layer, but nuclei appear at different levels; contains goblet cells and cilia.
• Location: Upper respiratory tract.
• Function: Secretion and movement of mucus.

Transitional Epithelium (Bladder)

• Appearance: Haphazard arrangement, with domed 'umbrella' cells on the surface when unstretched.
• Location: Ureters and bladder.
• Function: Elasticity, allowing stretch and retract.

Connective Tissue

Areolar Connective Tissue

• Appearance: Contains collagen, elastic, and reticular fibers; contains fibroblasts, macrophages, plasma cells, adipocytes, mast cells, and some white blood cells.
• Location: In and around nearly every body structure, supporting epithelial tissues.
• Function: Cushioning, inflammation, holding, and conveying tissue fluids.

Adipose Tissue

• Appearance: Primarily adipocytes; fibers are absent.
• Location: Subcutaneous areas, around the heart and kidneys, and in yellow bone marrow.
• Function: Insulation, energy reserve, and padding.

Reticular Connective Tissue

• Appearance: Primarily reticular fibers.
• Cells: Reticular cells and white blood cells.
• Location: Liver, spleen, and lymph nodes.
• Function: Stroma (scaffolding) and filtering.

Dense Regular Connective Tissue

• Appearance: Collagen fibers are regularly arranged and parallel.
• Cells: Fibroblasts.
• Location: Tendons and ligaments.
• Function: Resists tension in one direction.

Dense Irregular Connective Tissue

• Appearance: Collagen fibers are irregularly arranged.
• Cells: Fibroblasts.
• Location: Fasciae of skin and muscle, reticular layer of dermis and capsules around various organs like the heart, kidney, liver, lymph nodes, and bone.
• Function: Resists tension in multiple directions.

Elastic Connective Tissue

• Appearance: Primarily elastic fibers.
• Cells: Fibroblasts.
• Location: Aorta, other elastic arteries, and lungs.
• Function: Elasticity.

Hyaline Cartilage

• Appearance: Collagen with a glassy appearance.
• Cells: Chondrocytes in lacunae.
• Location: Ends of long bones, costal cartilage, nose, larynx, trachea, bronchi, and fetal skeleton.
• Function: Support, flexibility, and smooth surface (joints).

Fibrocartilage

• Appearance: Collagen fibers.
• Cells: Chondrocytes in lacunae.
• Location: Pubic symphysis, intervertebral discs, and menisci of the knee.
• Function: Resists compressive forces.

Elastic Cartilage

• Appearance: Elastic fibers.
• Cells: Chondrocytes in lacunae.
• Location: Epiglottis and pinna of the ear.
• Function: Elasticity.

Bone Tissue

• Appearance: Circular osteon (compact bone) or trabeculae (spongy bone); contains osteocytes in lacunae.
• Location: Bone.
• Function: Support, protection, storage, and hematopoiesis.

Blood Tissue

• Appearance: Blood plasma with formed elements, including erythrocytes, leukocytes, and thrombocytes.
• Location: Within the cardiovascular system.
• Function: Transport of respiratory gases, nutrients, and waste; involved in immune response and clotting.

Muscle Tissue

Skeletal Muscle (Voluntary)

• Appearance: Long, parallel, striated fibers; multinucleate at the periphery.
• Location: Attached to bones by tendons.
• Function: Motion, posture, heat production, and protection.

Cardiac Muscle (Involuntary)

• Appearance: Short, bifurcate, striated fibers; uninucleate with intercalated discs.
• Location: Heart wall.
• Function: Pumps blood through vasculature.

Smooth Muscle (Involuntary)

• Appearance: Long, spindle-shaped, non-striated, and uninucleate.
• Location: Walls of hollow organs (blood vessels, intestines, etc.) and iris of eyes.
• Function: Motion, such as constricting vessels, moving food through the gastrointestinal tract, and contraction of the bladder.

Nervous Tissue

• Appearance: Neurons (dendrites and axon) and neuroglia.
• Location: Nervous system.
• Function: Sensitive to various stimuli, converts stimuli to nerve impulses, and conducts impulses to other neurons, muscles, or gland cells.