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.

to protect Classified based on thickness and shape

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 = eyelashes (see next page)

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.