Transcript Biol 155 Human Physiology - Department of Zoology, UBC

Tissues and tissue types
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Tissues are:
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Collections of specialized cells and cell products
organized to perform a limited number of functions
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Histology = study of tissues
The four tissue types are:
Epithelial
 Connective
 Muscular
 Nervous
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Epithelial tissue
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Includes glands and epithelium
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Glands are secretory
Is avascular
Forms a protective barrier that regulates
permeability
Cells may show polarity
Functions of epithelium
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Physical protection
Control permeability
Provide sensation
Produce specialized secretions
Specializations of epithelium
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Perform secretory functions
Perform transport functions
Maintain physical integrity
Ciliated epithelia move materials across their
surface
The Polarity of Epithelial Cells
Maintaining the integrity of
epithelium
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Cells attach via cell adhesion molecules (CAM)
Cells attach at specialized cell junctions
Tight junctions
 Desmosomes
 Gap junctions
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Intercellular connections
Structure of typical epithelium
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Basal lamina attaches to underlying surface
Lamina lucida
 Lamina densa
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Germinative cells replace short-lived epithelial cells
Classification of epithelia
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Number of cell layers
Simple
 Stratified
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Shape of apical surface cells
Squamous
 Cuboidal
 Columnar
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Squamous Epithelia
Cuboidal Epithelia
Cuboidal Epithelia
Columnar Epithelia
Columnar Epithelia
Columnar Epithelia
Transitional Epithelium
Glandular epithelia
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Exocrine glands
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Secrete through ducts onto the surface of the gland
Endocrine glands
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Release hormones into surrounding fluid
Glandular secretions can be:
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Merocrine (product released through exocytosis)
Apocrine (involves the loss of both product and
cytoplasm)
Holocrine (destroys the cell)
Mechanisms of Glandular
Secretion
Glands
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Unicellular
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Individual secretory cells
Multicellular
Organs containing glandular epithelium
 Classified according to structure
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A Structural Classification of
Exocrine Glands
Connective tissue functions:
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Establishing a structural framework
Transporting fluids and dissolved materials
Protecting delicate organs
Supporting, surrounding and interconnecting
tissues
Storing energy reserves
Defending the body from microorganisms
A Classification of Connective
Tissues
Connective tissues contain
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Specialized cells
Matrix
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Composed of extracellular protein fibers and a ground
substance
Connective tissue proper
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Contains varied cell populations
Contains various fiber types
A syrupy ground substance
Fluid connective tissue
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Contains a distinctive cell population
Watery ground substance with dissolved
proteins
Two types
Blood
 Lymph
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Supporting connective tissues
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Less diverse cell population
Dense ground substance
Closely packed fibers
Two types
Cartilage
 Bone
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Connective tissue proper
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Contains fibers, a viscous ground substance, and a varied cell
population.
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The ground substance is the non-living material in which the cells
and protein fibres are found.
 Can contain varying amounts of water.
 Can be of viscous (blood), semi-solid (cartilage) or solid (bone).
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The ground substance and the extracellular proteins form the
matrix.
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Types of cells found in connective tissue:
Macrophage
 Adipocytes
 Mesenchymal cells
 Fibroblasts
 Melanocytes
 Mast cells
 Lymphocytes
 Microphages
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Connective tissue proper
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Three types of fiber
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Collagen fibers
Reticular fibers
Elastic fibers
Connective tissue proper
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Classified as loose or dense
Loose
Embryonic mesenchyme, mucous connective tissues
 Areolar tissue
 Adipose tissue
 Reticular tissue
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Dense
Dense regular CT
 Dense irregular CT
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The Cells and Fibers of Connective
Tissue Proper
Connective Tissue in Embryos
Adipose and Reticular Tissues
Dense Connective Tissues
Dense Connective Tissues
Dense Connective Tissues
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Fluid connective tissues
Distinctive collections of cells in a fluid matrix
Blood
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Formed elements and plasma
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Red blood cells, white blood cells and platelets
Arteries carry blood away, veins carry to the heart
 Capillaries allow diffusion into the interstitial fluid
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Lymph
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Interstitial fluid entering the lymphatic vessels
Formed Elements of the Blood
Supporting connective tissues
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Cartilage and bone support the rest of the body
Cartilage
Grows via interstitial and appositional growth
 Matrix is a firm gel containing chondroitin sulfate
 Cells called chondrocytes
 Cells found in lacunae
 Perichondrium separates cartilage from surrounding
tissues
 Three types: hyaline, elastic and fibrocartilage
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The Perichondrium and Types of
Cartilage
The Perichondrium and Types of
Cartilage II
The Perichondrium and Types of
Cartilage III
Bone, or osseus tissue
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Has osteocytes
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Depend on diffusion through canaliculi for
nutrients
Little ground substance
Dense mineralized matrix
Surrounded by periosteum
Bone
Membranes are simple organs
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Form a barrier
Composed of epithelium and connective tissue
Four types
Cutaneous
 Synovial
 Serous
 Mucous
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Membranes
Mucous membranes
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Line cavities that communicate with the exterior
Contain lamina propria
Serous membranes
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Line sealed internal cavities
Form transudate
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Cutaneous membrane
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Covers the body surface
Synovial membrane
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Incomplete lining within joint cavities
Organs and systems are
interconnected
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Network of connective tissue proper consisting of
Superficial fascia
 Deep fascia
 Subserous fascia
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The Fasciae
Muscle tissue
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Specialized for contraction
Three types
Skeletal
 Cardiac
 Smooth
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Muscle Tissue
Muscle Tissue
Muscle Tissue
Skeletal muscle
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Cells are multinucleate
Striated voluntary muscle
Divides via satellite cells
Cardiac muscle
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Cardiocytes occur only in the heart
Striated involuntary muscle
Relies on pacemaker cells for regular contraction
Smooth muscle tissue
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Non-striated involuntary muscle
Can divide and regenerate
Neural tissue
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Conducts electrical impulses
Conveys information from one area to another
Neural tissue cells
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Neurons
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Transmit information
Neuroglia
Support neural tissue
 Help supply nutrients to neurons
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Neural Tissue
Neural anatomy
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Cell body
Dendrites
Axon (nerve fiber)
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Carries information to other neurons
Inflammation and regeneration
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Injured tissues respond in coordinated
fashion
Homeostasis restored by inflammation
and regeneration
Inflammatory response
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Isolates injured area
Damaged cells, tissue components and dangerous
microorganisms removed
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Infection avoided
Regeneration restores normal function
An Introduction to Inflammation
Aging and tissue repair
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Change with age
Repair and maintenance less efficient
Structure altered
Chemical composition altered
Aging and cancer incidence
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Incidence of cancer increases with age
70-80% of all cases due to exposure to
chemicals or environmental factors
Changes in a Tissue under Stress