Vertebrate Tissues Mrs. Stahl Zoology
Dec 16, 2015
Vertebrate Tissues
Mrs. StahlZoology
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.