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TISSUES & STRUCTURES 1
INTRODUCTION
Cellular level e.g. cell: smallest living units in body.
Derived from 3 germ layers.
Tissue level e.g. gastric tissue: groups of cells working together to perform one or two functions.
Organ level e.g. stomach: same type of tissue but functions as independent unit in an integrated system.
System level e.g. Gastrointestinal: collection of organs & structures with a common function.
Organism level e.g. human
Every part of human body made up of one or more main tissue types viz.:-Epithelial-Connective-Muscle-Nervous
EPITHELIAL TISSUE
Covers exposed surfaces, lines internal passageways and chambers and forms glands.
Functions
Provide physical protection
Control permeability
Provide sensation
Produce specialized secretions
Three descriptors:
1) Lining
2) Glandular
LINING EPITHELIUM
Simple (one layer)
-Squamous
-Cuboidal
-Columnar
-Pseudostratified
Two types: Simple, Stratified
Stratified (many layers)-Squamous
-Transitional
SIMPLE SQUAMOUS
Shape: thin, flat and irregular; like jigsaw puzzles
Most delicate type
Located in regions where absorption or diffusion takes place or in slippery places e.g. Body cavity.
Function: reduce friction, control vessel permeability, perform absorption and secretion.
lines ventral body cavities (mesothelium); heart & bld vsls(endothelium), nephrons of kidney, inner lining of cornea, alveoli in lungs.
SIMPLE CUBOIDAL
Shape: resemble hexagonal boxes, have nuclei at center
Function: limited protection, absorption and secretion.
lines glands, ducts, portions of kidney tubules, thyroid gland.
Structures:
Cell membrane
Nucleus
cytoplasm
SIMPLE COLUMNAR
Shape: rectangular, hexagonal, taller, more slender.
Elongated nuclei close to basal lamina
Located in regions where absorption or secretion occurs e.g. small
intestine.
In stomach & large intestine, protects from chemical stresses.
Function: protection, absorption and secretion.
lines stomach, intestine, gallbladder, uterine tubes and collecting ducts of kidneys. Structures:
Surface of tissue
Mucus
Goblet cells
Nucleus
PSEUDOSTRATIFIED COLUMNAR
Has several types of cells with varying shapes and functions.
Not truly stratified because every cell contacts the basal lamina.
Possess cilia
lines nasal cavity, trachea, bronchi, portions of male repr. Tract.
Function: protection and secretion.
Structures
Cilia
Surface of tissue
Goblet cells
Nuclei
STRATIFIED SQUAMOUS
Has keratin (protein) is exposed areas to dehydration
Non-keratinized resists abrasion.
Located where mechanical stresses are severe e.g. esophagus.
Located in surface of skin (keratinized), lining of mouth, throat,
esophagus, rectum, anus and vagina.
Function: physical protection.
Structures
Surface
Squamous cells
Reproducing cells
STRATIFIED CUBOIDAL
Rare
Located along ducts of sweat glands and in larger ducts of mammary
glands.
Function: protection, absorption and secretion.
lines some ducts. Similar to simple type but with more layers
STRATIFIED COLUMNAR
Relatively rare
Has either two or multiple layers.
Located in small areas of pharynx, epiglottis, anus, mammary gland, salivary gland ducts, and urethra.
Function: protection
TRANSITIONAL
Tolerates repeated cycles of stretching and recoiling without
damage
Appearance changes with stretching
Located urinary bladder, renal pelvis of kidneys, ureters.
Function: permits expansion and recoil.
GLANDULAR EPITHELIUM
Endocrine
Release secretions to interstitial fluid (bloodstream).
Secretions called hormones
Ductless glands
Examples: thyroid, pituitary, pancreas, thymus.
Exocrine
Release secretions into ducts
Enzymes entering GIT, skin, tears and mammary glands.
Common mode of secretion: merocrine (mucin-mucus).
ENDOCRINE GLANDS
EXOCRINE GLANDS
CLASSIFICATION
Modes of secretion
Merocrine Apocrine Holocrine
Types of secretions
Serous (parotid) Mucous (sublingual) Mixed (submandibular)
Structure
-unicellular (goblet cells)
-& multicellular
Structure: simple & compound Shape (tubular: straight or coiled; alveolar)Simple:
Tubular straight in intestinal glands
Tubular coiled in sweat glands
Alveolar: sebacious glands
Compound: tubular (mucous gl. Mouth), testes
Alveolar: mammary gl., salivary, pancreas.
EXOCRINE GLANDS..secretions
Release from vesicle
Loss of cytoplasm
Destroys gland cell
EXOCRINE GLANDS..structure
CONNECTIVE TISSUE
Connective tissue proper
Loose areolar
Adipose
Dense regular
Dense irregular
*Also called collagenous tissue (rich in collagen fibers)
Supporting connective tissue
Fibrous
Hyaline cartilage
Elastic cartilage
Fibrocartilage
LOOSE AREOLAR
Separates skin from deep structures, loosely organized fibers (superficial fascia) Absorbs shock
Has elastic fibers hence returns to shape Has capillaries for 02 and nutrients
Surround and support blood vessels and nerves
Structures:
Ground substance
Fibroblast
Collagenous fiber
Elastic fiber
ADIPOSE TISSUE
Located deep to skin esp. at sides, buttocks, breasts, padding around eyes and kidneys.
Function: provides padding and cushions shock, insulates (reduces heat loss); stores energy.
Either white (yellowish) or brown in colour
RETICULAR TISSUE
Location: Liver, kidney, spleen, lymph nodes and bone marrow.
Functions: Provides supporting framework.
Reticular fibers (black)
DENSE REGULAR TISSUE
Located tendons & aponeurosis, ligaments, covering skeletal muscle as deep fascia.
Functions: provides firm attachment, conducts pull of muscle, reduces friction, stabilizes relative positions of bones.
Collagen fibers
Fibroblast nuclei
DENSE IRREGULAR
Located on capsules of visceral organs, periostia and periochondria, nerve and muscle sheaths, dermis.
Functions: provides resistance to forces from different sides, prevents overexpansion such as bladder.
Collagen fiber bundles
ELASTIC TISSUE
Located in ligamentum flavum and nuchae, ligaments supporting penis, ligaments supporting transitional epithelium, blood vessel walls.
Functions: stabilizes positions of vertebrae and penis, cushions shocks, permits expansion and contraction
Elastic fibers
Fibroblast nuclei
FLUID CONNECTIVE TISSUE.blood tissue
Red Blood Cells (RBCs)
Platelets
Tiny pockets
of cytoplasm
WHITE BLOOD CELLS (WBCs)
For immune system (protection from infection and disease)
Monocyte
Lymphocytes
Eosinophil
Neutrophil
Basophil
SUPPORTING CONNECTIVE TISSUEcartilage
Matrix is firm gel containing polysaccharides
Cartilage cells called chondrocytes occupying lacunae
Separated from other structures by perichondrium
TYPES
HYALINE
ELASTIC
FIBROCARTILAGE
HYALINE CARTILAGE
Location: between tips of ribs and bones of sternum e.g. costal cartilage, bone surfaces of synovial joints, supports larynx, trachea and bronchi, form
part of nasal septum.
Function: provides stiff, flexible support; reduces friction.
Chondrocyte in lacuna
Nucleus
Ground substance
ELASTIC CARTILAGE
Located in auricle of external ear, epiglottis, auditory tube, cuneiform cartilages of larynx.
Functions: provides support, tolerate distortion without damage & returns to original shape.
Similar to hyaline except abundant
elastic fibers
FIBROCARTILAGE
Located in menisci, pubic symphysis, intervertebral discs.
Functions: Resists compression, prevents bone to bone contact, limits relative movement.
Chondrocytes in lacuna
Collagen fibers
NERVOUS TISSUE
A) Neurons
MYELIN
produced by Oligodendrocytes in CNS and Schwann cells in PNS
Functions in enhancing conduction rates.
NEUROGLIA
Protoplasmic astrocytes (in dendrites and cell bodies of CNS) [Gray matter]
Fibrous astrocytes (in myelinated axons) [white matter)
B) Connective tissue
MUSCLE TISSUE
Skeletal
Smooth
Cardiac
SKELETAL MUSCLE
Cells are long, cylindrical, striated and multinucleate. Voluntary
Located in skeletal muscles with connective and neural tissue. Function: Moves or stabilizes position, guards entrances and exits to digestive,
respiratory, and urinary tracts, generates heat, protects internal organs.
Parallel muscle fibers
Striations
Nuclei
CARDIAC MUSCLE
Cells are short, branches, striated, usually with a single nucleus, cells are interconnected by intercalated discs.
Involuntary
Location: Heart
Function: Circulates blood, maintains blood pressure.
Cardiac muscle cellsNucleusStriationsIntercalated discs (black)
SMOOTH MUSCLE
Cells are short, spindle-shaped, non-striated with a single nucleus.
Involuntary
Location: walls of blood vessels and in digestive, respiratory, urinary and reproductive organs.
Smooth muscles cellNucleus
BONE TISSUE
Has small ground substance
2/3rds have mixture of calcium salts (primarily calcium phosphate), rest by collagen fibers.
Canaliculi
Osteocytes in lacuna
Haversian canals
TISSUES & STRUCTURES 2
SYSTEMS
SYSTEMATIC ANATOMY
The Integumentary System
The Skeletal System
The Nervous System
The Muscular System
The Cardiovascular System
The Respiratory System
The Gastrointestinal System
The Urogenital System
The Endocrine System
The Immune/Lymphoid System
INTEGUMENTARY
Protects against environmental hazards, helps control body temperature
SKELETAL SYSTEM
Provides support, protects tissues, stores minerals, forms blood.
MUSCULAR SYSTEM
Produces movement and locomotion; provides support; generates heat.
NERVOUS SYSTEM
Directs immediate response to stimuli, usually by coordinating the activities of other organ systems.
ENDOCRINE SYSTEM
Directs long-term changes in other organ systems.
CARDIOVASCULAR SYSTEM
Transports cells and dissolved materials including nutrients, wastes and gases.
LYMPHOID SYSTEM
Defends against infection and disease; returns tissue fluid to bloodstream
RESPIRATORY SYSTEM
Delivers air to sites where gaseous exchange can occur between air and circulating blood.
DIGESTIVE SYSTEM
Processes food, absorbs nutrients, eliminates waste products.
URINARY SYSTEM
Eliminates excess water, salts, and waste products.
FEMALE REPRODUCTIVE SYSTEM
Produces sex cells and hormones.
MALE REPRODUCTIVE SYSTEM
Produces sex cells and hormones