Vertebrate Tissues Mrs Stahl Zoology Tissue A group

Vertebrate Tissues Mrs. Stahl Zoology

Tissue • A group or mass of similar cells working together to perform a common function. • The study of tissues= Histology • Animal Tissues: – Epithelial – Connective – Muscle – Nervous

Epithelial Tissue • Covers or lines something and typically consists of sheets of cells that have surface specializations adapted for their specific roles. • Functions: Size, shape, and arrangement directly relate to these specific functions – Absorb- lining of the intestines – Transport- Kidney tubules – Excrete- Sweat and Endocrine Glands – Protect- The Skin – Contain nerve cells for sensory reception- taste buds on the tongue.

Classified based on thickness and shape to protect

Classification of epithelia • According to thickness – “simple” - one cell layer – “stratified” – more than one layer of cells (which are named according to the shape of the cells in the apical layer) • According to shape – “squamous” – wider than tall – “cuboidal” – as tall as wide – “columnar” - taller than wide

Epithelial Tissue

Epithelium-Human Stomach

Simple Squamous • Single layer, simple, flattened. • Function- diffusion and filtration • Location- air sacs of lungs, walls of capillaries, covering visceral organs (hollow organ), lining body cavities

Simple Cuboidal • Single layer, cube shaped • Function- secretion / absorption • Location- Lining of kidney tubules, ducts of glands (salivary and pancreatic), cover the surface of the ovaries

Simple Columnar • Single layer, elongated cells with the nucleus located in the same spot • Function- protection, absorption, secretion • Location- lining of the digestive tract and uterus, gall bladder – Some have fingerlike projections called microvilli which increase surface absorption – Contains scatter goblet cells functioning in the secretion of mucus

“ciliated” literally = (see next page) eyelashes

Stratified Squamous • Multi-layered, thicker • Function- protection • Location- lining of body cavities like the mouth and outer layer of the skin, nasal cavity, esophagus, vagina, and anal canal (non-keratinized). Keratinized -> epidermis of the skin

Stratified: regenerate from below

Pseudostratified Columnar • Stratified appearance but really a single layer with nuclei at various levels giving the layered look, ciliated, have goblet cells • Function- secretion and cilia aided movement • Location- lining air passages -> trachea, auditory tubes of the reproductive system

Transitional Epithelium • Thick, layered cuboidal cells, stretchable forms a barrier to block diffusion • Location- lining of urinary bladder

Special Features of Epithelium • Cilia- hair-like appendages attached to the apical surface of cells that act as sensory structures or to proton movement • Goblet Cells- specialized cells that produce mucus to lubricate and protect the surface of the organ. • Villi- fingerlike projections that arise from the epithelial layer in some organs. Increase surface area allowing for faster and more efficient absorption • Microvilli- smaller projections that arise from the cells surface. Increased surface area, bushy appearance.

Connective Tissue • Characteristics: – Most abundant tissue in your body (made up of ground substance (fluid and semi-solid) and fibers – Binds structures together, stores nutrients, cells reproduce – Provides support, protection, framework, fills space, stores fat, produces blood cells, fights infection – Extracellular matrix- a bed of secreted organic material of varying composition that binds separated cells of tissue. Nonliving material between cells.

Classes of Connective Tissue: note the cell types and great variety of subclasses

2 General Types • 1. Loose Connective Tissue: strong, flexible fibers of the protein collagen are interwoven with fine, elastic, and reticular fibers, giving its elastic consistency and binding capabilities. • 2. Fibrous Connective Tissue: Densely packed collagen fibers and they may lie parallel to one another creating very strong cords (ex- tendons and ligaments) – Tendons- connect muscles to bones – Ligaments- connect bones to bones

Connective Tissue • Originate from embryonic tissue called mesenchyme-> rises from the mesoderm, an embryonic germ layer (stem tissue)

Common Cell Types • Adipocytes- adipose tissue cells • Fibroblasts- most common, secrete collagen proteins that are used to maintain a structural framework, play an important role in healing wounds. • Osteocytes- bone cells, are trapped within the bone matrix (the hard part of the bone), has tentacle like dendrites that allow it to maintain contact with neighboring cells / communicate.

• Mast cells- tissue of the immune system of vertebrate animals. Mediate inflammatory responses-> allergic reactions. They are scattered all over the connective tissue. Chemical mediators produce responses-> inflammation, swelling, contraction of smooth muscles, increased mucus production

Adipose • Large cells • Function= protection, insulation, stores energy • Location= beneath the skin, around kidneys, eyeballs, abdominal membranes

Cartilage • Cells= chondrocytes • Hard, flexible, supports ears, skeleton of sharks and rays • Hyaline- most common, covers ends of bones and joints, respiratory passages • Elastic- flexible and elastic, external ear, larynx • Fibrocartilage- very tough , large, menisci (cartilage where two bones meet), intervertebral disks

Bone Cells • Osteocytes • In the lacunae (cavity or depression, especially in bone) • Support and protection • Surrounded by calcium phosphate and calcium carbonate= making the tissue really hard

Blood • Plasma-> made up of mostly water but suspends red blood cells , white blood cells, and platelets. • Transports various substances throughout the body of an animal.

Nervous Tissue • Found in the brain, spinal cord and nerves • Composed of: – Neurons- impulse conducting cells – Neuroglia- protection, support, and nourishment – Peripheral Glial Cells- form sheaths and help protect, nourish, and maintain cells of the peripheral nervous system (outside the brain and spinal cord)

Muscle Tissue • Muscle cells= myofibers • Function: movement, digestion, organ function • 3 kinds: Skeletal, Smooth, and Muscle

Skeletal • Attached to bones and makes body movement possible in vertebrates • Smooth-

Smooth • Rhythmic contractions create a churning action (stomach), help propel material through tubular structures (intestines), and control size changes in hollow organs (uterus, urinary bladder)

Cardiac • Wall of the heart • Results in the heart beating

Tissue Repair • Regeneration- replaces dead or damaged cells with the same type of cell, restoring normal function • Fibrosis- replaces damaged tissue with scar tissue, which holds the tissues together but does not restore normal functions.