Transcript The Tissue Level of Organization

The Tissue Level of
Organization
Introduction

Histology: the study of tissues
– Tissue: composed of cells, and extracellular
materials & fluids
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4 Types of Tissues:
– A) Epithelial: covers surfaces, lines passageways
& chambers, produces gland secretions
– B) Connective: fills internal spaces, supports &
binds organs, stores energy
– C) Muscle: contracts to produce movement
– D) Neural: conducts electrical impulses & carries
info throughout body
Epithelial Tissue
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Includes epithelia & glands
 Functions:
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1) Provides protection
2) Controls skin permeability
3) Provides sensation
4) Produces gland secretions
Epithelial Cells (con’t)
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Shapes:
– Squamous
– Cuboidal
– Columnar
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Arrangements:
– Simple: single layer
– Stratified: multiple layers
– Pseudostratified: single layer, but appears to be
multi-layered
• All cells attach to basement membrane
Epithelial Tissue - Simple
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Simple Squamous: lines ventral body
cavities & blood vessels
– decreases friction, provides absorption & secretion
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Simple Cuboidal: glands & ducts
– protection, absorption, secretion
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Simple Columnar: lines stomach, intestines,
gallbladder, uterine
– protection, absorption, secretion
Epithelial Tissue - Other
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Pseudostratified Ciliated Columnar: lines
nasal cavities, trachea & bronchi
– protection & secretion
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Transitional: urinary bladder, ureters
– allows expansion & recoil for stretching
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Stratified Squamous: skin surface, lines
mouth, throat, esophagus
– protects against abrasion, pathogens & chemicals
Connective Tissue
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Includes: bone, cartilage, blood, fat, etc.
 Composed of:
– specialized cells surrounded by a matrix (protein
fibers & ground substance fluid)
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Functions:
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1) Support & Protection
2) Transport of Materials
3) Energy Storage
4) Body Defenses
Types of Connective Tissue
Connective Tissue Proper Types
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1) Loose “areolar”
– Separates skin from muscle, provides padding, &
contains extensive blood supply
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2) Adipose (loose with many fat cells)
– Provides shock absorption, insulation, energy
storage
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3) Dense “fibrous/collagenous”
– Tendons: connect muscle to bone
– Ligaments: connect bone to bone
Supporting Connective Tissue
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Cartilage: composed of chondrocyte cells &
covered in perichondrium; NO blood supply
– Hyaline cartilage: connects ribs to sternum &
covers joints
– Elastic Cartilage: forms outer ear & epiglottis
– Fibrocartilage: pad between vertebrae & in pubic
bone
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Bone: composed of osteocyte cells &
covered in periosteum; EXTENSIVE blood
supply
“Membranes”
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May refer to plasma membrane, a
barrier (i.e. basement membrane), OR
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A covering composed of epithelia
tissue & connective tissue
Types of Membranes
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1) Mucous: line cavities that communicate
with the exterior (i.e. respiratory,
reproductive, & urinary tracts)
– Kept moist by secretions & fluids
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2) Serous: line sealed, internal divisions of
body cavities (i.e. heart, lungs, etc.)
– ↓ friction & allows for movement
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3) Cutaneous: covers the body (skin)
– Provides thick, waterproof protection
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4) Synovial: fills cavities in bone joints
– Lubricates and ↓ friction in joints
Muscle Tissue
Contraction involves the action
of myosin & actin proteins
 3 Types:
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– 1) Skeletal: composed of large,
multinucleated cells
• Most large muscles in the body
• Appear striped, or STRIATED
• Under VOLUNTARY control of
nervous system
Muscle Tissue (con’t)
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Types:
– 2) Cardiac: striated, but composed
of small, single-nucleus cells
• Compose most of the heart
• Controlled by pacemaker cells in
heart (not nervous system)
• Under INVOLUNTARY control
– 3) Smooth: non-striated &
composed of long, slender singlenucleus cells
• Line blood vessels, urinary bladder,
resp. & digest. tracts
• Under INVOLUNTARY control of
nervous system
Neural Tissue
Conducts electrical impulses throughout
the body
 Mostly found in brain and spinal cord
 Composed of 2 types of cells:
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– 1) Neurons: send & receive impulses
– 2) Neuroglia: provide support, nutrition, &
defense for neurons
Tissue Injury and Repair
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After injury happens, 2 processes occur:
– 1) Inflammation: includes swelling, warmth,
redness, & pain
• Mast cells release chemicals to ↑ blood flow & stimulate
nerve endings at injured area
– 2) Regeneration: fibroblasts produce scar tissue
• Skin, most connective tissues, & smooth muscles
regenerate well
• Striated muscles & nerve cells do not
• Fibrosis: replacement of cardiac tissue with fibrous
connective tissue