Lecture 2 Basic Tissue Flashcards
HISTOLOGY:
• Study of the
microscopic structure and function of tissues.
TISSUES:
Structure formed by the grouping of cells with similar characteristics of form and function.
4 BASIC TYPES OF TISSUES
- Epithelial Tissue:
• forms protective coverings
• function in secretion and sensory - Connective Tissue:
• provides support for softer body parts
• binds structures together - Muscular Tissue:
• responsible for producing body movements.
Muscular Tissue:
• responsible for producing body movements. - Nerve Tissue:
• specialized to conduct impulses that help control and coordinate body activities.
Epithelial Tissue:
Simple: squamous, cuboidal, columnar, pseudostrat ified
Stratified: squamous (keratinized, nonkeratinized), cuboidal, columnar, transitional
Connective Tissue:
Solid soft: connective tissue proper, specialized (adipose, fibrous, elastic, reticular)
Solid firm: cartilage
Solid rigid: bone
Fluid: blood, lymph
Muscle
Involuntary: smooth, cardiac
Voluntary: skeletal
Nerve
Afferent: sensory
Efferent: motor
Basic tissues
Embryological Cell Layers
The basic tissue types of the body form from three embryological cell layers:
• Ectoderm
Mesoderm
• Endoderm
These embryological cell layers develop from embryonic cells during prenatal development (more on this later).
- EPITHELIAL TISSUE
• Covers and lines both the external and internal body surfaces, including vessels and small cavities.
• Serves as a protective covering or lining but is also involved in tissue:
- absorption
- secretion
- sensory
- other specialized functions.
• Protects complex inner structures from:
- physical, chemical and pathogenic attacks
- dehydration
- heat loss (acts as a barrier).
• Depending on classification, epithelial tissue can be derived from any of the three embryonic cell layers:
•Ectoderm:
- skin and oral mucosa
• Endoderm:
- respiratory and digestive tract
• Mesoderm:
- urinary tract
EPITHELIUM
• Cells packed closely together:
- surrounded by very little or no intercellular substance or tissue fluid.
• Epithelium is highly regenerative (its deeper cells reproduce by mitosis)
• Epithelial cells are:
- tightly joined together by desmosomes.
- joined to basement membrane by
hemidesmosomes.
EPITHELIAL CELLS:
EPITHELIUM
• Epithelium is avascular, having no blood supply of its own.
• Cellular nutrition (oxygen and metabolites) is obtained by DIFFUSION from the connective tissue:
• connective tissue is highly vascularized, providing its own source of nutrition
EPITHELIUM CLASSIFICATION
Cell Arrangement: Simple -1 layer, single layer of cells
Stratified - 2 or more layers (many layers)
Pseudostratified -1 layer but looks like 2
—Cell Shape:Squamous - flat
Cuboidal - cube
Columnar - rectangular
Transitional - changes shape
—Cell Function:Keratin - dead layer, no nucleus
(protection)
Cilia - hair-like projections
(propel other substances along.
Ex: fallopian tubes and egg)
EPITHELIUM: DIVISION
Simple:
• Squamous
• Cuboidal
• Columnar:
- ciliated
- non-ciliated
• Pseudostratified
Stratified:
• Squamous
- keratinized
- non-keratinized
• Cuboidal
• Columnar
• Transitional
Pseudostratified:
• Ciliated
• Non-ciliated
SIMPLE SQUAMOUS EPITHELIUM
SIMPLE SQUAMOUS EPITHE
• Very thin, flat cells, may vary in shape.
• Covers connective tissue with little intercellular matrix, attached by the basement membrane.
• Performs a filtering function on moist surfaces.
Endothelium: simple squamous epithelium lining of vessels and serou cavities (surround organs).
Location:
pulmonary alveoli (lungs)
-
inner and middle ear -
blood and lymphatic vessels -
heart -
serous cavities
SIMPLE SQUAMOUS EPITHELIUM
SIMPLE CUBOIDAL EPITHELIUM
SIMPLE CUBOIDAL EPITHE
• Cube-like cells, top view:
hexagon.
• Nucleus is in the center of the cell.
• Protection / covering for an organ.
• Contributes to secretion.
Location:
• Line the ducts of various glands, such as ducts of the salivary glands.
SIMPLE CUBOIDAL EPITHELIUM
SIMPLE COLUMNAR EPITHELIUI
• Rectangular: height greater than width, top view:
hexagon.
• Nucleus near the base of the cell.
• Function: protection, secretion/absorption due to goblet cells (secrete mucin: a carbohydrate-protein complex found in most secretions).
• May or may not be ciliated (having cilia) on surface
- carries mucous and debris towards exterior.
Location:
• Non-ciliated:
- stomach
- large/small intestine
- lining of cervical canal
• Ciliated:
- uterus
- fallopian tubes
- ductus deferens (male reproductive system)
- small intra-pulmonary bronchi (lungs)
SIMPLE COLUMNAR EPITHELIUM
PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
EPITHELIUM
• Crowded columnar cells (rectangular form is destroyed).
• Nuclei are at different levels.
• Serves to moisten, warm and clean lining membranes.
• May be ciliated or non-ciliated.
Location:
• Upper respiratory tract including nasal cavity and para nasal sinuses
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PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
• Many layers of cells on an irregular basal laver.
• No layer of keratin.
• Kept moist from bodily secretions (ex: saliva), not the membrane itself:
- bodily secretions prevent it from drying out.
• Range from cuboidal to squamous cells, can have polyhedral shaped cells.
Cells are continually being replaced.
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
Location:
• Buccal and alveolar mucosa
• Ventral part of tongue (underneath)
• Soft palate
• Floor of the mouth
• Sulcular epithelium
• Esophagus
• Cornea
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
STRATIFIED SQUAMOUS KERATINIZED EPITHELIUM
• Located on dry surfaces.
• Has a keratin layer for protection.
• Great cell differentiation among its 5 layers:
1. Stratum basale
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum (palms & soles, not in oral cavity)
5. Stratum corneum (dead, non-nucleated)
KERATIN:
• Tough, fibrous, opaque, waterproof protein.
• Resists friction.
• Impervious to bacteria and other invaders.
• 1st line of defense.
• Nuclei are condensed and inactive.
STRATIFIED SQUAMOUS
KERATINIZED EPITHELIUM
STRATIFIED SQUAMOUS
KERATINIZED EPITHELIUM
Location:
• Skin
• Free gingiva (outside only)
• Attached gingiva
• Hard palate
• Dorsal of tongue
• Lips
TRANSITIONAL EPITHELIUM
• Ranges between stratified squamous non-keratinized and stratified columnar epithelium.
• Ranges from polyhedral to dome shaped, flat cells.
• Cells are soft, pliable, and loosely arranged.
TRANSITIONAL EPITHELIUM
TURNOVER TIME
Epithelial cells are capable of rapid turnover-
• The time it takes for the newly divided cells to be completely replaced through the tissue:
• Skin is about 27 days.
• Oral cavity is about 14 days.
BASEMENT MEMBRANE
Thin, acellular structure
Located between the epithelium and connective tissues
3 layers make up the basement membrane:
- Lamina Lucida (clear layer)
Basal Lamina - Lamina Densa (dense layer)
Lamina, Basal - Reticular Lamina (contains collagen and reticular fibers)
- CONNECTIVE TISSUE
- CONNECTIVE TISSUE
• The functions of connective tissue are varied depending on the type:
- connects, supports, protects, provides frameworks, fills spaces, stores fat, produces blood cells, provides protection against infection and helps repair tissues.
Cells are usually some distance apart and have considerable amount of matrix between them consisting of fibers and intercellular substance.
Connective Tissue
MAJOR CELL TYPES
MAJOR CELL TYPES
• Fibroblasts:
- Most common cell type found in all CT.
- Synthesize certain types of protein fibers and intercellular substances needed to sustain the connective tissue.
- Fixed cells (do not leave tissue).
• Macrophages (Monocytes) - most common WBC:
- Function as phagocytes (ingest bacteria, dead and dying cells).
- Important in fighting infections.
• Mast Cells (Basophils) - involved in allergic responses:
- May release heparin (anticoagulant) and histamine (increases permeability of WBCs). Usually located near blood vessels.
CONNECTIVE TISSUE FIBERS
COLLAGENOUS FIBERS:
• Composed of collagen and have great tensile strength.
CONNECTIVE TISSUE FIBERS
ELASTIC FIBERS:
• Composed of microfilaments embedded in protein elastin.
This tissue has the ability to stretch and return to its original shape.
• Ex: Soft palate.
RETICULAR FIBERS:
• Composed of the protein reticulin, are very fine, hair like fibres that branch, forming a network in the tissue.
• Ex: lymph nodes and spleen.
BREAKDOWN OF CONNECTIVE TISSUE
• LOOSE CONNECTIVE TISSUE
• FIBOROUS CONNECTIVE TISSUE
• ADIPOSE TISSUE
• ELASTIC CONNECTIVE TISSUE
• RETICULAR CONNECTIVE TISSUE
• CARTILAGE
• BONE
• HEMOOETIC TISSUE
LOOSE CONNECTIVE TISSUE
LOOSE CONNECTIVE TISSUE
• Forms thin membranes between organs and binds them together.
Serves as protective padding for the deeper structures of the body.
Location: beneath the skin (dermis) and between muscles.
• Intercellular space contains tissue fluid.
FIBOROUS CONNECTIVE TISSUE
• Aka dense connective tissue
• Composed mainly of strong collagenous fibers that bind parts together.
• Location: tendons, ligaments, eyes, skin (dermis).
ADIPOSE TISSUE
• A specialized form of loose connective tissue that stores fat, provides a protective cushion and functions as a heat insulator.
• Cells packed tightly together with little or no matrix.
• Location: beneath the skin (hypodermis), in certain abdominal membranes, oral cavity and around the kidneys, heart and various joints.
ELASTIC CONNECTIVE TISSUE
• Composed mainly of elastic fibers which combine strength with elasticity.
• Gives an elastic quality to the walls of certain hollow internal organs and vocal cords.
RETICULAR CONNECTIVE TISSUE
• A delicate network of interwoven reticular fires forming a supportive framework.
• It supports the walls of blood vessels, internal organs such as the liver and spleen and the lymphatic organs.
CARTILAGE
Provides support and framework for various parts and
decreases friction.
• Intercellular material is composed of mainly collagen fibers and intercellular substance, therefore it is similar to soft connective tissue but the matrix of cartilage is much firmer.
• It lacks a direct blood supply and is slow to heal following an injury.
• The connective tissue surrounding most cartilage is the perichondrium, a fibrous connective tissue sheath containing blood vessels.
CARTILAGE
Types of cells found in Cartilage:
2 Types of cells found in Cartilage:
1. Chondroblasts:
- produce cartilage matrix, lie internal to the perichondrium.
2. Chondrocytes:
- mature chondroblasts that maintain the cartilage matrix.
LACUNA is what?
• Lacuna - small spaces surround the chondrocyte within matrix.
Cartilage
MAJOR TYPES OF CARTILAGE
- HYALINE CARTILAGE
- ELASTIC CARTILAGE
- FIBROCARTILAGE
HYALINE CARTILAGE
HYALINE CARTILAGE
• Chondrocytes (mature chondroblasts) are located in lacuna (small space surrounding the chondrocyte) which is surrounded by intercellular material containing very fine collagenous fibers.
• All cartilage begins as hyaline cartilage then modifies into other types as needed.
• Location: embryonic skeleton and growth centers, mandibular condyle.
ELASTIC CARTILAGE
ELASTIC CARTILAGI
• In addition to many collagen fibers, contain elastic fibers.
• Location: external ear, auditory tube, epiglottis and parts of the larynx.
- Nucleus
FIBROCARTILAGE
FIBROCARTILAGE
• Is never found alone and merges gradually with its neighbouring hyaline cartilage.
• Considered transitional cartilage between hyaline cartilage and the dense connective tissue of tendons and ligaments.
• Cells are enclosed in capsules of matrix giving it great tensile strength.
• Serves as a shock absorber and a protective cushion.
• Location: intervertebral discs, between bones in the pelvic girdle, and TMJ.
FIBROCARTILAGE
Bone
BONE
• Rigid connective tissue that constitutes most of the mature skeleton.
• Bone matrix contains mineral salts and collagen.
• Cells are arranged in concentric circles around osteonic canals and are interconnected by canaliculi (cytoplasmic processes), which allows interaction between osteocytes (mature osteoblasts).
• Bone tissue heals rapidly, highly vascularized.
• Manufactures blood cells via red bone marrow and stores calcium and other minerals.
• Provides an internal support for body structures and protects vital parts in the cranial and thoracic cavities.
• Serves as an attachment for muscles.
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BONE
CELLS
Osteogenic Cells:
• Stem cells which will differentiate into osteoblasts.
• Located on the inner layer of periosteum (double-layered dense connective tissue sheath).
Osteoblasts:
• Typical blast cell that produces protein components of bone matrix, builds bone.
Osteocytes:
• Mature osteoblasts trapped in the bone matrix within the lacunae.
Osteoclasts:
• Bone-resorbing cell located in
Howship’s lacunae (shallow pits caused by resorption).
OSTEOCLASTS
BONE ARCHITECTURE
Osteon:
• The unit of structure in compact bone and consists of 5 to 20 lamellae.
Haversian Canal:
• Central vascular canal within each osteon surrounded by the lamellae.
• Runs longitudinally and that contains nerves and blood vessels.
• Provides nutrition for the bone.
Volkmann’s Canal:
• Same as Haversian canal except it runs obliquely or at right angles to the Haversian canals of the osteons and large blood vessels.
• Located on the outer portion of the
Haversian system.
Lamellae:
• Organized arrangement of concentric sheets (like the growth rings in a cross section of a tree.
BONE ARCHITECTURE
Lacuna - surround osteocytes:
• Spaces between lamellae (sheets) where osteocytes are imbedded.
Canaliculi:
• Tubular canals radiating from the lacuna into the lamella where cytoplasmic processes of osteocytes are located.
Sharpey’s Fibers:
Serve to anchor periosteum firmly to bone.
Periosteum:
• Double layered, dense connective tissue sheath, outer layer contains blood vessels and nerves and inner layer contains single layer of osteoblasts (bone growth).
BONE ARCHITECTURE
OSSIFICATION
Development of bone.
2 methods of growth, same result.
1) INTRAMEMBRANOUS:
• Formation of osteoid (young, unmineralized bone) within 2 dense connective tissue sheets which eventually replaces the outer connective tissue.
Uses appositional growth (layers).
• Occurs in fontanelles (soft infant skull spots), maxilla, majority of the mandible.
OSSIFICATION
2) ENDOCHONDRAL:
• Formation of osteoid within a hyaline cartilage.
• Uses interstitial growth from pre-existing cartilaginous model, later appositional growth of osteoid occurs to complete the process.
Occurs in long bones (it is how we grow taller), vertebrae, ribs, head of mandible, base of skull.
IMMATURE BONE
(Primary Bone):
(Primary Bone):
• First bone produced by either method.
• Indistinct lamellae.
• Irregular arrangement of collagen fibers.
• Many cells present.
MATURE BONE
(Secondary Bone):
MATURE BONE
(Secondary Bone):
• Replaces primary bone.
• Distinct lamellae
• Very organized arrangement of collagen fibers.
• Fewer cells.
HEMOPOETIC TISSUE
BLOOD:
• Fluid connective tissue that transports cellular nutrients, such as respiratory gases like oxygen and carbon dioxide, as well as metabolites for the entire body.
• Specialized because it does not contain fibers.
• Red and white blood cells in plasma.
• Cells are formed by a special tissue in the hollow parts of certain bones (bone marrow).
CELLULAR COMPONENTS OF BLOOD
RED BLOOD CELLS:
• Biconcave disc, no nucleus, 1/3 is hemoglobin.
• Transports oxygen and carbon dioxide.
‘ELLULAR COMPONENTS OF BLOOD
Platelets (thrombocytes):
• Smaller than RBC, no nucleus, disc shaped.
• Helps control blood loss from broken vessels by functioning in clotting mechanism.
CELLULAR COMPONENTS OF BLOOD
WHITE BLOOD CELL (LEUKOCYTE) - have a nucleus
Neutrophil (PM, polymorphonuclear leukocyte): destroys small particles by phagocytosis, 1st to arrive to the site of injury, acute, inflammatory response is triggered, especially with phagocytosis.
Neutrophil
Neutrophil (PMN, polymorphonuclear leukocyte): destroys small particles by phagocytosis, 1st to arrive to the site of injury, acute, inflammatory response is triggered, especially with phagocytosis.
Eosinophil
Eosinophil - kills bacteria and helps control inflammation and allergic
reactions.
Basophil
Basophil - helps control inflammation and allergic reactions.
Monocytes
Monocytes- contains lysosomal enzymes involved in destroying particles
by phagocytosis, later stages of inflammation.
Lymphocytes
Lymphocytes - mechanism of immunity, chronic. B cells, T cells and NK
cells (natural killers).
Mast cells
Mast Cells - allergic response, contains heparin and histamine.
- MUSCLE TISSUES
GENERAL CHARACTERISTICS
Muscle tissue is contractile tissue that moves parts attached to it.
Three types of muscle tissue:
1. Skeletal
2. Smooth
3. Cardiac
SKELETAL MUSCLE TISSUE
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• Voluntary muscle.
• This tissue is attached to bones and is controlled by conscious effort.
• Cells (muscle fibers) are long and threadlike wi alternating light and dark cross-markings (striations).
• Muscle fiber bundles (fascicles) are composed of myofibers which are composed of smaller myofibrils which in turn are composed of even smaller myofiliaments.
• Muscle fibers contract when stimulated by nerve action, then relax immediately.
STRUCTURE OF A MUSCLE
SMOOTH MUSCLE TISSUE
• Found in walls of hollow internal organs, glands, and linings of blood vessels.
• Controlled by involuntary activity.
CARDIAC MUSCLE TISSUE
CARDIAC MUSCLE TISSUE
• This tissue is found only in the heart.
• Cells are joined by intercalated discs and arranged in branched, interconnecting networks.
• Cardiac muscle tissue is controlled by involuntary activity.
- NERVE TISSUE
- NERVE TISSUE
• Nerve tissue forms the nervous system in the body.
• It is found in the brain, spinal cord and peripheral nerves.
• Nerves function to carry messages or impulses based on electrical potentials.
NERVOUS System
NEURON: Cell of the nervous system.
DENDRITES: Processes that lead impulses to the cell body.
AXON: Process that leads impulses away from the cell body.
BODY: Metabolic processes of the cell, not part of transmission of impulses.
NERVE: Neural processes in the peripheral nervous system (PNS).
SYNAPSE: Neural impulses between 2 neurons or a neuron and an effector organ (muscle or a gland).
GANGLION: Aggregation (grouping) of neuron cell bodies outside the CNS.
NEURONS
• Sensitive to change and respond by transmitting nerve impulses to other neurons or to other body parts.
• They function in coordinating and regulating body activities.
AFFERENT vs EFFERENT NERVES
AFFERENT VS EFFERENT NERVES
AFFERENT (SENSORY) NERVE:
• Carries information from the PS to the CNS (like pain and taste).
EFFERENT (MOTOR) NERVE (AUTONOMIC):
• Carries information from the CNS to the PNS.
