ANIMAL TISSUES

Types of Animal Tissues

Epithelial Muscular Supporting

and Connective

Vascular Nervous

Epithelial tissue

Forms the outer coverings and inner linings of the body surfaces

Has tightly packed cells with very little intercellular material

For protection, selective absorption, and secretion

Epithelial Groups

covering and lining epithelial membranes squamous epithelium -- tile-like cells

- epidermis, inner cheek cells

cuboidal epithelium -- dice-shaped cells, specialized for secretion, makes up the epithelium of kidney tubules and many glands

- thyroid gland and salivary glands

columnar epithelium found in the linings of the digestive tract, cells are longer than they are wide

ciliated epithelium line the upper respiratory tract so that mucus and dust particles can be moved along their surfaces

Epithelial Groups

glandular epithelium-specialized for production of secretory substances

- unicellular glands goblet cells lining the intestine

- multicellular glands-when large amts of secretions are reqd, the surface epithelia grow inward or become infolded exocrine (with ducts carry secreted substances onto body

surfaces or into body cavities) salivary glands

endocrine (ductless) gastric glands

Muscular Tissue

specialized for movement muscle cells are called muscle fibers long,

spindle-shaped thread-like structures movement is thru contraction of muscle fibers

Types of Muscular Tissue 1. Nonstriated (Smooth) muscles - involuntary - found in the visceral organs except the heart; in the

outer wall of intestine and stomach and blood vessels -parts: sarcoplasm,myofibrils(contractile elements of the

muscle cell-cant be seen in slide), sarcolemma-cell membrane

2. Striated muscles - characterized by the presence of dark bands

(anisotropic or A-discs) and light bands (isotropic or I-discs)

- myofilaments finer filaments w/in the myofibrils arrangement of myosin and actin filaments gives rise

to dark and light bands

Types of Muscular Tissue Multinucleated condition or Syncytium in striated muscular

tissues - achieved by fusion of myoblasts (immature nucleated

muscle cells) into muscle fibers in adult organisms, when embryonic myoblasts no longer divide. Addl nuclei are also contributed by integration of peripheral muscle satellite cells; numerous mitoses but no cytokinesis

2.1 skeletal - muscles that are attached to the bones, voluntary (under control of will)

2.2 cardiac or heart muscles - involuntary - is a functional syncytium plasma membranes of adjacent cells interlock at specialized regions called

intecalated discs, where gap junctions provide direct electrical coupling between the cells. Thus, the action potential generated by specialized cells in one part of the heart spreads to all other cardiac muscle cells, causing the whole heart to contract.

Supporting and Connective Tissue

Characterized by the presence of a large amount of intercellular material (as contrasted with epithelial tissue) and paucity of cells

Connective tissue cells - fibrocytes

Functions:

To attach or connect parts

To support or bear weight

To provide a medium thru which nutrients and wastes may diffuse

Types of Supporting and Connective Tissue Fibrous connective tissue white or collagenous fibers fine, wavy fibers occurring in bundles in the dermis of the skin Cartilage-intercellular subs not calcified cartilage cells - chondrocytes - located in the lacunae surr by intercellullar subs/matrix (less diff-flattened; fully diff big & round) Hyaline-nose, ventral rings of trachea, endoskel of adult sharks Elastic-external ear of mammals (pinna), Eustachian tube Fibro-cartilage- joints, intervertebral disc in b/w vertebrae

Types of Supporting and Connective Tissue

Bone intercellular subs is calcified

Osteocytes bone matrix is laid down in rings called lamellae interconnected by means of Volkmanns canal * Bone prepared via grinding wont show the osteocytes but only the lacunae since they have been displaced by grinding

Vascular (blood) Tissue

Made up of liquid component, plasma and blood cells/formed elements

Also considered as a mobile connective tissue since it transfers nutrients and wastes from tissue to tissue in an organism

Origins of blood cells traced to conn tish hemapoietic tissue of the marrow

Types of Vascular (Blood) Tissue

1. Erythrocytes/Red blood corpuscles contains hemoglobin, responsible for oxygen and CO2 transport to

and from the lungs and other tissues Frog-oval, nuc; human-biconcave, enuc

2. Leucocytes/White blood corpuscles Soldiers of the body, engulf pathogens and facilitate immune

response. Frog-smaller & fewer than rbcs; humans-larger and fewer

A.Polymorphonuclear leucocytes-irreg nuclei Neutrophils

nuclei is made up of 2 to 5 or more thin lobes connected by slender chromatin thread

granules are fine and does not stain well at neutral pH Eosinophils

nuclei are made up of 2 oval lobes linked by thread like chromatin granules are coarse and stain pinkish red with acid stains

Basophils nuclei stain very faintly has coarse cytoplasmic granules that stain blue with basic dye

B. Lymphocytes nuclei are large, somewhat spherical; there is only narrow rim

of cytoplasm around the nucleus

C. Monocytes nuclei vary from slightly indented ovals to horseshoe-shaped

structures have larger amounts of cytoplasm than lymphocytes

Frog Blood

Nervous Tissue

nerve cell neuron cytoplasm is drawn out into long nerve fibers, the

dendrites and the axon dendrites carry impulse toward the cell body axon carries impulse away from the cell body

nerve a bundle of nerve fibers bound by connective tissues : epineurium is the loose connective tissue covering inside a nerve are fascicles or nerve bundles each fascicle is covered by a perineurium - a dense connective

tissue endoneurium encloses individual nerve bundles