Chapter 4 Histology: Study of Tissues. TISSUE TYPES Epithelial Connective Muscle Nervous.
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Transcript of Chapter 4 Histology: Study of Tissues. TISSUE TYPES Epithelial Connective Muscle Nervous.
Chapter 4
Histology: Study of Tissues
TISSUE TYPES
• Epithelial• Connective• Muscle• Nervous
Embryonic Development
• Blastocyst- ball of cells• Germ layers:
– Endoderm- outer layer– Mesoderm- middle layer– Ectoderm- inner layerGastrulation- process of blastocyst to
germ layersHistogenesis- process of germ layers
developing into different kinds of tissues.
Epithelial Tissue
• Types & locations– membranous: cover/lining; found in
serous cavities, bld & lymph vessels, respiratory, digestive & genitourinary tracts.
– Glandular: grouped in solid cords or specialized follicles that form secretory units of endocrine & exocrine glands.
Epithelial Tissue
• Functions– Protection– Sensory functions– Secretion– Absorption– Excretion
Epithelial Tissue
• Generalizations– Limited matrix material– Connects to connective tissue– Avascular– Cells tightly packed – Frequently replace themselves
Epithelial Tissue• Classifications
– Membranous epithelium• Classification based on cells shape
– Squamous cells– Cubiodal cells– Columnar cells– Pseudostratified columnar cells
Epithelial Tissue• Classifications
– Classification based on layers of cells• Simple epithelium • Stratified epithelium• Transitional epithelium
Epithelial Tissue
• Glandular epithelium– Unicellular glands- single-celled glands;
Goblet Cells– Multicellular glands- clusters, solid
cords, specialized follicles– Exocrine glands- secrete into ducts– Endocrine glands- ductless glands
Connective Tissue Categories
• Embryonic or mesenchyme• Adult
– Loose– Dense– Connective tissue with special
properties– Cartilage– Bone– Blood
Extracellular Matrix
• Components– Protein fibers
• Collagen which is most common protein in body• Reticular fill spaces between tissues and organs• Elastic returns to its original shape after
distension or compression
– Ground substance• Shapeless background
– Fluid
Loose Connective Tissue
• Also known as areolar tissue• Loose packing material of most organs and tissues• Attaches skin to underlying tissues• Contains collagen, reticular, elastic fibers and variety
of cells
Dense Connective Tissue• Dense regular
– Has abundant collagen fibers• Tendons: Connect muscles to bones• Ligaments: Connect bones to bones
• Dense regular elastic• Ligaments in vocal folds
• Dense irregular• Scars
• Dense irregular collagenous• Forms most of skin dermis
• Dense irregular elastic• In walls of elastic arteries
Connective Tissue with Special Properties
• Adipose tissue- Fat storage– Consists of adipocytes– Types
• Yellow (white)– most abundant, white at birth and yellows
with age• Brown
– found only in specific areas of body as axillae, neck and near kidneys
• Reticular tissue– Forms framework of lymphatic tissue– Characterized by network of fibers and cells
Cartilage
• Composed of chondrocytes located in spaces called lacunae• Next to bone firmest structure in body• Types of cartilage
– Hyaline– Fibrocartilage– Elastic
Hyaline Cartilage
• Found in areas for strong support and some flexibility– Rib cage and cartilage in trachea and bronchi
• Forms most of skeleton before replaced by bone in embryo
• Involved in growth that increases bone length
Fibrocartilage
• Slightly compressible and very tough• Found in areas of body where a great deal
of pressure is applied to joints– Knee, jaw, between vertebrae
Elastic Cartilage
• Rigid but elastic properties– External ears, epiglottis
Osseous Tissue
• Commonly called bone tissue
• Function is to support & protect
• Made of osteocytes• Compact Bone• Cancellous or
Spongy Bone
Blood
• Matrix between the cells is liquid
• Hemopoietic tissue– Forms blood cells– Found in bone
marrow• Yellow• Red
Muscle Tissue• Characteristics
– Contracts or shortens with force– Moves entire body and pumps blood
• Types– Skeletal- moves bones
• Striated and voluntary
– Cardiac- pumps heart• Striated and involuntary
– Smooth- covers organs; moves fluids• Nonstriated and involuntary
Nervous Tissue
• Found in brain, spinal cord and nerves
• Ability to produce action potentials• Cells
– Nerve cells or neurons• Consist of dendrites, cell body, axons• Consist of multipolar, bipolar, unipolar
– Neuroglia or support cells
Membranes• Mucous
– Line cavities that open to the outside of body
– Secrete mucus• Serous
– Line cavities not open to exterior• Pericardial, pleural,
peritoneal• Synovial
– Line freely movable joints– Produce fluid rich in
hyaluronic acid
Inflammation• Response when
tissues damaged or with an immune response
• Manifestations– Redness, heat,
swelling, pain, disturbance of function
• Mediators– Include histamine,
kinins, prostaglandins, leukotrienes
– Stimulate pain receptor and increase blood vessel permeability