Tissues
Definitions
• Tissues are groups of cells that have the same structure and functions.
• The study of tissues is called HISTOLOGY– Histos: tissue; ology: field of study
Classification of tissues
• Epithelial– Simple (one layer)
• Squamous• Cuboidal• Cilindrical
– With microvilli or “brush border”.– Cilia
• Pseudostratified– Stratified (several layers)
• Squamous• Cuboidal• Cilindrical• Transition
Classification of Tissues
• Connective– Proper
• Mesenchyme• Loose connective
– Areolar– Reticular– Adipose
• Dense connective tissue– Dense regular– Dense irregular
– Cartilage• Hyaline• Elastic• Fibrocartilage
– Oseous– Blood
Classification of Tissues
• Muscular– Skeletal muscle– Cardiac muscle– Smooth muscle
• Nervous tissue
Epithelial tissue
• Characteristics– Polarity: posses apical surface and basal surface.– Cellularity and special contacts (tight junctions).– Supported by connective tissue through basement
membrane (basal lamina + reticular lamina).– Avascular: no blood vessels.– Regenerative: cells regenerate.
• Function: lining of surfaces (interior or exterior to the body)
Figure 3.5
Simple Epithelium
• Simple Squamous epithelium: – Description: “scale like” flat cells.– Function: Allows passage of substances
through filtration and diffusion. – Located in endothelium (lining of blood
vessels), kidney glomeruli, air sacs in the lung (alveoli).
Figure 4.1
Simple squamous
Figure 4.2
Simple Epithelium
• Simple cuboidal epithelium– Description: cells are of cubic form. – Function: secretion and absortion. – Located in kidney tubules, ovary surface
Figure 4.3
Simple Epithelium
• Simple Columnar (cilindrical) epithelium– Description: tall cells with round or oval nucleus. – Function: Absorption that can be increase by
cytoplasmatic projections of microvilli, secretion of mucus. If ciliated, it propels mucus by ciliary action.
– Located in digestive track, small intestine, uterus, lower respiratory system (bronchioles).
Figure 4.4
Figure 4.5
Simple Epithelium
• Pseudostratified columnar:– Description: single layer of cells, with
apparent different heghts due to the position of the nucleus.
– Function: secretion and propulsion of mucus.
– Located in the trachea.
Figure 4.6
Simple Epithelium
• Pseudostratified columnar– Description: appears to be stratified
squamous and cylindrical. – Function: allows stretching and containing
urine (avoiding leakage into adjacent tissues). – Found in the bladder.
Stratified Epithelium
• Stratified Squamous epithelium– Description: multilayer squamous cells. – Function: protection of underlying tissues. – Location: Non keratinized (thin skin) are found
in the esphagous, mouth,vagina. Keratinized (thick skin): palm and feet.
Figure 4.7
Stratified Epithelium
• Stratified Cuboidal epithelium– Description:bilayer of cuboidal cells. – Function: secretion. – Found in the ducts of glands such as
mammary, sweat and salivary.
Figure 4.8
Stratified Epithelium
• Stratified Columnar epithelium– Description: Several layers of cylindrical cells. – Function: secretion. – Found in the male urethra.
Figure 4.9
Stratified Epithelium
• Transitional epithelium– Description: Resembles both stratified
sqamous and stratified cuboidal epithelium; basal scells are cuboidal or cylindrical; surface cells are domed or squamous.
– Function: Allows distension and stretching. – Found in the lining of the urethers, bladder
and par of the urethra.
Figure 4.10
Connective Tissue Proper
• Areolar loose connective tissue
– Description: loose collagen reticular and elastic fibers, prescence of fibroblasts, macrophages, mast cells.
– Function: wraps provide nutrients and cushions organs.
– Found under epithelia, surrounds capillaries and packages organs, .
Connective Tissue
• Function: Support/connect tissues.• Description:
– Cells:• Fibroblast: most common.• Chondrocytes, ostoecytes: secrete respective extracellular matrix.• Myofibroblasts• Adipocytes
– Fibres• Collagen• Estastin• Reticulin
– Ground substance: amorphous transparent material.• Glucosaminoclycans (GAGs): Hyaluronic acid• Glycoproteins: fribrillin, fibronectin, integrin.
Figure 4.11
Connective Tissue Proper
• Reticular loose connective tissue– Description: predominant reticular fibers in a
network. – Function: Provides structure to lymph organs.– Located: Found in lymph organs (thymus,
lymph nodes).
Figure 4.13
Connective Tissue Proper
• Regular Dense connective tissue– Parallel arranged collagen fibers with
fibroblasts. – Function: Attaches muscles to bones or bones
to bones. Posses great tensile strength in one direction.
– Forms tendons, ligaments, aponeurosis.
Figure 4.15
Connective Tissue Proper
• Irregular Dense connective tissue– Description: Irregular arranged fibers with
fibroblasts. Forms the articulation capsules of organs and joints.
– Function: Posses great tensile strength in several directions.
– Location: reticular layer of the dermis, fibrous capsues of organs and joints.
Figure 4.14
Connective Tissue Proper
• Elastic Connective tissue– Description: Irregular arranged elastic fibers
with fibroblasts. Makes the tunica media in blood vessels.
– Function: Provides elasticity to the blood vessels.
– Location: Tunica media of arteries and veins.
Figure 4.16
Connective Tissue Proper
• Adipose loose connective tissue– Description: adipocytes embeded in scarce
areolar tissue.– Function: Energetic reserve, cushioning,
thermal insulation.– Location: Hypodermis, kidneys, abdomen,
breasts.
Figure 4.12
Cartilage
• Hyaline Cartilage:– Description: firm amorphous matrix
synthesized by chondroblasts. Mature matrix holds chondrocytes in lacunae.
– Function: Allows resilience, flexibility and compressibility to forces.
– Located: embryonic skeleton, joints, nose, trachea, ribs.
Figure 4.17
Cartilage
• Elastic cartilage:– Description: similar to hyaline, but a grater
ratio of elastic fibers.– Function: maintain structure while possesing
great flexibility.– Location: outer ear, epiglotis.
Figure 4.18
Cartilage
• Fibrocartilage:– Description:similar to hyaline but a greater
ratio of collagen fibers.– Function: posses high tensile strength but
maintaining compressibility.– Located: intervertebral discs, knee joint, pubic
symphisis.
Figure 4.19
Bone
• Compact bone– Description: Hard, calcified matrix.
Impereameable. Vascularized. Osteocytes in lacunae.
– Function: hematopoiesis (reb blood cell formation), storage of calcium and minerals. Composes the skeleton.
– Location: bones
Figure 4.20
Figure 4.21
Blood
• Description: red, white cells and fibrous proteins (firbinogen) in a fluid matrix (plasma)
• Function: transport of nutrients, wates, gases throughout the body.
• Located: within blood vessels.
Figure 4.22
Muscle
• Skeletal muscle– Description: long, cylindrical, multinucleated,
and striated.– Function: Voluntary movement; locomotion.– Located: skeleton
Figure 4.28
Figure 4.30
Muscle
• Cardiac Muscle– Description: branched, striated, uninucleated
cells, connected by cell juntions (intercalated discs)
– Function: propulsion of blood from the heart.– Location: heart.
Figure 4.31
Muscle
• Smooth muscle– Description: spindle shaped, uninucleated, no
striations.– Function: creates peristaltic movement in
digestive system and involuntary contraction of arrestor pili.
– Lacted: hollow organs, dermis
Figure 4.32
Nervous tissue
• Description: Composed mainly by neurons and support cells (glial cells).
• Function: transmit electrochemical signals to sense and control the body.
• Location. Brain, spinal cord, nerves.
Figure 4.33
Figure 4.35
Figure 4.37
Figure 4.38
• Note: to extra practice, you find an atlas in the lab book as well as a tutorial in the PhysioEx CD.
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