Animal Tissues: Types, Locations, & Functions

• The notes cover various tissue types, detailing their locations, functions, and structures.
• The tissue types include: epithelial, connective, muscle, and nervous tissue.

Simple Cuboidal Epithelial

• Location: Kidneys and ovaries, lining kidney tubules and ducts of some glands.
• Function: Secretion and absorption.
• Structure: Single layer, cube-shaped cells with centrally located, spherical nuclei.

Simple Squamous Epithelial

• Location: Lung alveoli, capillary walls, blood vessels, Bowman's capsule of the kidney, and covering membranes.
• Function: Diffusion and filtration.
• Structure: Single layer of thin, flat cells with broad, thin nuclei.

Simple Columnar Epithelium

• Location: Small intestine, uterus and ovarian tubes (ciliated), and most organs of the digestive system (non-ciliated).
• Function: Protects underlying tissues, secretes digestive fluids, and absorbs digested nutrients. Microvilli increase the surface area for absorption.
• Structure: Single layer of elongated cells, thick tissue with nuclei near the basement membrane.

Stratified Squamous Epithelium

• Location: Esophagus and outer layer of the skin (keratinized). Also lines the mouth, throat, vagina, and anal canal (non-keratinized).
• Function: Prevents water loss, blocks chemicals and microorganisms.
• Structure: Relatively thick, cells divide in deeper layers, pushing old cells upward. Keratinization provides a dry, tough covering of dead cells.

Transitional Epithelial

• Location: Bladder, ureters, and part of the urethra.
• Function: Provides an expandable lining and prevents diffusion from the urinary tract.
• Structure: Several layers of cuboidal cells able to stretch.

Pseudostratified Columnar Ciliated Epithelial

• Location: Trachea (ciliated) and epididymis/vas deferens (non-ciliated).
• Function: Goblet cells secrete mucus swept away by cilia; cilia move particles toward the pharynx (in the trachea).
• Structure: Appears layered due to nuclei at different levels, possesses cilia.

Areolar Tissue (Connective Tissue Proper - Loose)

• Location: Beneath layers of epithelium.
• Function: Binds skin to underlying organs and fills spaces between muscles.
• Structure: Delicate, thin membranes of fibroblasts in a gel-like matrix.

Adipose Tissue (Connective Tissue Proper - Loose)

• Location: Beneath the skin, between muscles, and around kidneys.
• Function: Cushions joints and organs, provides insulation, and stores energy.
• Structure: Cells store fat droplets, crowding out other cell types.

Reticular Tissue (Connective Tissue Proper - Loose)

• Location: Lymphoid organs (lymph nodes, bone marrow, and spleen) and liver.
• Function: Forms a soft internal skeleton (stroma) that supports other cell types like white blood cells, mast cells, and macrophages.
• Structure: Network of reticular fibers in a loose ground substance; reticular cells lie on the network.

Dense Irregular (Connective Tissue Proper - Dense)

• Location: Fibrous capsules of organs and joints, dermis of the skin, and submucosa of the digestive tract.
• Function: Withstands tension exerted in many directions and provides structural strength.
• Structure: Irregularly arranged collagen fibers, some elastic fibers, and fibroblasts.

Dense Regular (Connective Tissue Proper - Dense)

• Location: Tendons, most ligaments, and aponeuroses.
• Function: Attaches muscles to bones or to muscles, attaches bones to bones, and withstands great tensile stress when pulling force is applied in one direction.
• Structure: Parallel collagen fibers, few elastic fibers, and fibroblasts.

Elastic (Connective Tissue Proper - Dense)

• Location: Walls of large arteries, certain ligaments associated with the vertebral column, and walls of bronchial tubes.
• Function: Allows tissue recoil after stretching, maintains pulsatile blood flow, and aids lung recoil after inspiration.
• Structure: Dense regular connective tissue with a high proportion of elastic fibers.

Hyaline Cartilage (Connective Tissue - Specific, Cartilage)

• Location: Embryonic skeleton, ends of long bones in joint cavities, costal cartilages of ribs, cartilages of the nose, trachea, and larynx.
• Function: Supports and reinforces, serves as a resilient cushion, and resists compressive stress.
• Structure: Amorphous but firm matrix with an imperceptible collagen fiber network; chondroblasts produce the matrix, and chondrocytes lie in lacunae.

Compact Bone

• Location: Osteocytes (bone cells) form concentric circles in cross-section.
• Structure: Osteon - Haversian system.

Blood (Connective Tissue - Specific, Blood)

• Location: Forms in red bone marrow and inside blood vessels.
• Function: Transports respiratory gases, nutrients, wastes, and other substances, and maintains stable internal conditions.
• Structure: Red and white blood cells and platelets in a fluid matrix (plasma).

Skeletal Muscle Tissue

• Location: Attached to bone.
• Function: Moves head, trunk, limbs, facial expression, controlled by conscious effort (voluntary).
• Structure: Long, cylindrical, multinucleate cells.

Cardiac Muscle Tissue

• Location: Only in the heart.
• Function: Pumps blood, involuntary.
• Structure: Branching, striated, generally uninucleate cells that interdigitate at intercalated discs.

Smooth Muscle Tissue

• Location: Walls of hollow internal organs
• Function: Actions are involuntary, moves food through the digestive tract.
• Structure: No striations, shorter, spindle-shaped cells with central nuclei arranged closely to form sheets.

Nervous Tissue

• Location: Brain, spinal cord, ganglia, nerves.
• Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons.
• Structure: Neurons are branching cells with long processes extending from the cell body; non-excitable supporting cells.

Fibrocartilage (Connective Tissue - Specific, Cartilage)

• Location: Intervertebral discs, pubic symphysis, menisci of the knee joint.
• Function: Tensile strength allows it to absorb compressive shock.
• Structure: Matrix similar to hyaline cartilage, but less firm, contains thick collagen fibers.

Elastic Cartilage (Connective Tissue - Specific, Cartilage)

• Location: External ear (pinna) and epiglottis.
• Function: Maintains the shape of a structure while allowing great flexibility.
• Structure: Similar to hyaline cartilage, but with more elastic fibers in the matrix.

Compact (Cortical) Bone (Connective Tissue - Specific, Bone or Osseous)

• Location: Osteocytes (bone cells) form concentric circles in cross-section.
• Function: Internally supports body structures, provides protection, attachment for muscles, and stores/releases minerals (calcium).
• Structure: Rigid, contains minerals and a great amount of collagen. Osteon - Haversian system found here.

Spongy (Trabecular or Cancellous) Bone (Connective Tissue - Specific, Bone or Osseous)

• Location: Ends of long bones, proximal to joints, within the interior of vertebrae, and in the internal structure of short, flat, and irregular bones.
• Function: Contains red marrow (site for hematopoiesis) and provides support and protection for bone marrow.
• Structure: Less dense/lighter than compact bone, composed of trabeculae with open spaces.

Plantar Skin

• First layer: Keratinized epithelium.
• Second layer: Stratified squamous epithelium.
• Third layer: Dense irregular connective tissue.

Stratified Cuboidal Epithelial

• Location: Lines larger ducts of mammary glands, salivary glands, pancreas, and sweat glands.
• Function: Provides protection.
• Structure: Two or three layers of cuboidal cells.

Stratified Columnar Epithelial

• Location: Found in the male urethra.
• Function: Provides protection.
• Structure: Several layers of cells; superficial cells are elongated, basal cells are cube-shaped.

Glandular Epithelium

• Location: One or more of these cells constitutes a gland. Found within columnar and cuboidal epithelium.
• Function: Produce and secrete substances into ducts or body fluids.
• Structure: Specialized epithelial cells.

Lymph (Connective Tissue - Specific, Lymph)

• Location: Forms in tissue and located inside the lymphatic vessels.
• Function: Transports fat and other large molecules to the cardiovascular system, collects and transports tissue fluid back to circulation, and fluid matrix for the immune system.
• Structure: Fluid matrix (lymph).

Explore animal tissues: epithelial, connective, muscle, and nervous. Learn about simple cuboidal, squamous, and columnar epithelium. Understand their locations, functions, and structures within the body. Includes secretion, absorption, diffusion, and protection.