Download Tissues

Chapter 4
Klennex isn’t the Only Tissue
 Tissues are groups of cells with similar structures and
functions
 Histology is the study of them
 4 primary types
 Epithelial – covering an boundary formation
 Connective – support, protect, and bind
 Muscle – contractions cause movement
 Nervous - control and communication
 Organs often composed of all 4
Embryonic Development
 Zygote  blastocyst
 Cells organize into 3 primary
germ layers (gastrulation)

2nd- 3rd week
 Germ layers
 Ectoderm

Epidermis and nervous system
 Endoderm
 Linings of digestive and respiratory
tracts
 Mesoderm
 Skeletal, muscular, and circulatory
systems
Epithelial Tissue
 Covers or lines; glands too
 Functions reflect structure
 Protection, absorption, filtration, excretion, secretion, sensory
reception, and gas exchange
 Characteristics
 Cellularity: cells packed tight together, bound by tight junctions
and desmosomes
 Polarity

Apical and basal surfaces
 Connective tissue attachment


Basal lamina (noncellular) to reticular lamina (ECM)
Resists stretching and tearing
 Avascular, but innervated
 Regeneration

Friction and external substance exposure
Classifying Epithelia
Layer
Shape
 Simple: 1
 Absorbtion, secretion, and
filtration
 Stratified: 2+
 Protection
 Pseudostatified: looks 2+, but
 Squamous: flattened, scale-like
not
 Cuboidal: sides equal, box-like
 Columnar: taller than wide
 Transitional: varies
 Nuclei shape and apical layer
Simple … Epithelia
 Columnar
 Round/oval nuclei; possibly goblet cells
 Digestive tract, and gland ducts; small
bronchi, uterine tubes, and uterus
 Absorption, secretion of mucus, cilia
propels substances
 Cuboidal
 Large spherical central nuclei
 Kidney tubules, ducts of glands, and ovary
surface
 Secretion and absorption
 Squamous
 Disc-shaped central nuclei
 Kidney glomeruli, air sacs of lungs,
capillaries, linings of heart & lymphatic
system
 Diffusion and filtration; secretes lubricant
Additional Epithelia
 Pseudostratified columnar
 Nuclei at different levels; possible goblet
cells, cilia
 Male repo. tracts; respiratory tract
 Secretion and propulsion via cilia
 Stratified squamous
 Apically, basally cuboidal; living cells are
basal
 Surfaces that are exposed externally and
into all openings
 Protect abrasive surfaces
 Transitional epithelium
 Stratified and cuboidal basally, squamous
apically as urine volume increases
 Ureters, bladder, and urethra
 Change as urinary organs collect and
excrete
Glandular Epithelia
 Endocrine
 Ductless

Release hormones by exocytosis into blood
 Acts on target organ(s)
 Exocrine
 Possess ducts

Secretions onto body surface or within cavities
 1 or 2 secretion modes
 Merocrine: exocytosis, pancreas and sweat
 Apocrine: accumulate at apex and pinches off, mammary maybe
 Holocrine: accumulate and rupture, sebaceous
 Cellularity
 Unicelluar: goblet cells
 Multicellular
 Simple (unbranched): gastric and sebaceous
 Compound (branched): duodenal, mammary, and salivary
Connective Tissue
 Never exposed to environment outside the body
 Functions
 Protect, insulate, transport, support, and bind other
tissues together
 Characteristics
 Composed of multiple cell types
 Mesenchyme origin
 Range of vascularity
 Primarily extracellular matrix (ECM)
 Non-living; responsible for CT strength and abrasion
CT Structure
 Ground substance
 Unstructured space filler

Liquid, gel-like, or solid
 Fibers
 Collagen: tough with lots of collagen protein; white fibers
 Elastic: flexible and stretchable with lots of elastin protein;
yellow fibers
 Reticular: add extra support with collagen and glycoprotein
 Cells (-blast or –cyte)
 Fibroblast
 Chondroblast
 Osteoblast
 Hematopoietic stem cell
Connective Tissue Classification
Connective tissues
Fluid CT
CT Proper
Blood: in
circulatory
system
Loose: Fibers
loose, open;
i.e. adipose
Dense: Fibers
densly packed;
i.e. tendons
 Bold = 4 main types
Supporting CT
Lymph: in
lymphatic
system
Cartilage: solid,
Bone: solid,
rubbery matrix crystalline matrix
Loose CT
 Areolar
 Matrix with all 3 fibers and multiple cells
 Widely distributed throughout the body
 Lubricates and nourishes epithelia; strength;
elasticity; support; immune protection

Edema: inflammatory swelling of liquids
 Adipose
 Similar to areolar, but stores more nutrients
 Subcutaneous layer; around organs

Brown vs white fat
 Stores triglycerides; insulates; energy reserve;
protects
 Reticular
 Similar to areolar, but only reticular fibers
 Liver; spleen; lymph nodes
 Support and slow body fluids
Dense CT
 Dense regular
 Mostly parallel collagen fibers, some elastic

Wavy for stretch
 Attaches muscle to bone (tendon), muscle to
muscle (aponeuroses), bone to bone (ligament)
 Resists tension (1 direction), support, and
stabilization
 Irregular dense
 Collagen is thicker and not parallel
 Dermis; joint and organ capsules
 Resists tension (multiple directions)
Cartilage
 Avascular and w/o innervations
 Hyaline (gristle)
 Most abundant; chondrocytes in lacunae
 Ends of long bones (growth plates); ribs to
sternum; septum; respiratory system
 Support with pliability; compressive stress
 Elastic
 More elastic fibers than hyaline
 External ear and epiglottis
 Shape and flexibility
 Fibrocartilage
 Less firm than hyaline; thick collagen fibers
 Intervertebral discs; knee joint; pubic symphysis
 Resist compression; absorb shock; prevent bone
rubbing
Osseous Tissue
 Collagen fibers and calcium
salts
 Osteon
 Concentric lamellae
 Lacunae
 Osteocytes produce bone
 Osteoclasts breakdown bone
 Canaliculi
 Compact bone
 Spongy bone
Blood
 55% plasma
 90% water
 45% cellular components
 Erthrocytes
 Leukocytes
 Thrombocytes
Nervous Tissue
 Central nervous system
 Peripheral nervous system
 Most incapable of dividing
 Neurons
 Cell body
 Processes


Axon
Dendrites
 Neuroglia
Muscle Tissue
 Cellular and vascularized
 Myofilaments
 Responsible for movements
 Found through the body
 Skeletal
 Striated in appearance, multinucleate, voluntary
 Moves body parts
 Can’t divide, but partial regeneration
 Smooth
 No striations, uninucleate, involuntary
 Moves substance (object) along
 Can divide
 Cardiac
 Striated, uninucleate, involuntary
 Heart, has intercalated discs
 Can’t divide or regenerate
Membranes
 Cutaneous
 Exterior exposure; dry
 Stratified squamous and
dense irregular CT
 Mucous
 Exterior opening cavities;
‘moist membranes
 Str. squ or si. cub. and
loose CT
 Serous
 Si. squ. And loose CT
 Line ventral body cavity;
moist membranes