Download Cells, Tissues

INTRODUCTION TO CELLS &
TISSUES
By
Vijay Kapal
Graduate Studies Course CMM 5001
The Pathological Basis Of Disease
Fertilization
Fertilization of egg by the sperm
Sperm
Egg
+
(23 Chromo)
Sperm
(23 Chromo)
Fertilized egg (Zygote)
(46 Chromosomes)
Ovum (Egg)
Human body
Sperm
Zygote
Implantation
Zygote
Blastocyst
Uterus
Uterine glands
Maternal blood vessels
3-layered Flat Embryo
Ectoderm (1)
Mesoderm (3)
Endoderm (2)
Fertilized egg or Zygote (Single cell)
3-layers of cells
All Tissues & Organs of Human body
Human Genome
Nucleus
Cytoplasm
Cell membrane
Cell
Each cell has 46 chromosomes
Form 23 homologous pairs
Each parent contributes = 23
Autosomes = 44
Chromosomes (2N = 46)
Sex chromosomes = 2
Each autosome of a homologous pair look alike
(Male = XY, Female = XX)
But each sex chromosome do not look alike
Cell Cycle
Paclitaxel
Vincristine
Vinblastine
Colchicine
Nondividing cells
(Fixed postmitotics)
M
G0
G1
Resting cells
(Reverting
postmitotics)
G2
Bleomycin
Etoposide
S
Methotrexate
Mitosis & Meiosis
A Homologous Pair (2 Chromosomes)
1
1 pair
2
23 pair
1st Division
46
2nd Division
Daughter Somatic Cells (2)
Gametes (4)
Meiosis
Takes place only in testes and ovaries
Is a reductional division
Main purpose is to reduce the number of chromosomes from 2N to 1N in sperms &
eggs
(Chromosomes of each homologous pair will separate from each other)
Homologous pair = 1 chromosome from each parent (at fertilization)
2N = 46 chromosomes (2 sets)
1N = 23 chromosomes (1set)
So
Sperm = 1N chromosomes (23)
Egg
= 1N chromosomes (23)
Fertilization restores chromosome number again to 2N = 46 chromosomes (2 sets)
Human Body
Cells
Tissues
Cell
Organs
Human body
Tissue
Cell Organelles
• Nucleus
• Rough ER
• Smooth ER
• Golgi Complex
• Lysosomes
• Peroxisomes
• Mitochondria
• Cell Membrane
• Cell cytoskeleton
Chomatin, Transcription
Protein synthesis & Segregation
Fat & Steroid synthesis &
Detoxification
Concentrating, Modifying & Packaging
of secretory products
Intracellular digestion
Contain oxidative enzymes; Use catalase to
degrade H2O2 = H2O + O2
Oxydative phosphorylation & ATP production
Lipid bilayer layer with intramembranous
proteins
Actin filaments, Microtubules, intermediate
filaments
Cell Organelles
Mitochondria
Lysozome
Golgi
Nucleus
Rough ER
Cells, Tissues & Various Topics Of
Research
•
•
•
•
•
•
•
•
•
•
•
Subcellular localisation & trafficking of molecules and oganelles
Cell-cell and cell-extracellular matrix interactions
Cell cytoskeleton and receptor dynamics and functions
Cell and tissue differentiation and remodelling
Genetically engineered cells and tissues
Three-dimensional reconstructions, particularly of expression patterns
over time
Cell cycle and cell lineage analysis involving gene expression profiles
Apoptosis
Gene expression analysis from histological preparations
Functional genomics & proteomics
Techniques used in molecular histology
Epithelial Tissue
Outer layer of skin
Inner lining of
trachea
Inner lining of ducts
of sweat glands
General Features
•
•
•
•
•
•
•
•
Diversity
Metaplasia
Lining and Covering
Basal Lamina
Renewal
Avascularity
Cell Packing
Derivation
Classifying Principles
1. Number of cell layers:
1. Simple epithelia
2. Stratified epithelia
3. Pseudostratified epithelia
2. Shape of the surface cells:
1. Squamous cells
2. Cuboidal cells
3. Columnar cells
3. Luminal surface modifications:
1. Microvilli (Brush border)
2. Cilia
3. Stereocilia
Specific Epithelial Types
•
•
•
•
•
Simple squamous epithelium:
Simple cuboidal epithelium:
Simple columnar epithelium:
Pseudostratified epithelium:
Stratified Squamous epithelium:
a) Keratinized
b) Nonkeratinized
• Stratified cuboidal epithelium:
• Stratified columnar epithelium:
• Transitional epithelium:
Types of Epithelia
Simple squamous
Stratified squamous
Simple cuboidal
stratified cuboidal
Simple columnar
Pseudostratified
Transitional
Full
Empty
Bladder
Kidney (Epithelium)
Simple squamous
Simple cuboidal
Kidney Tubules
Small Intestine (Simple Columnar)
Absorptive cells
Nucleus
Brush border
Lamina propria
Lumen of gut
Esophagus (Stratified Squamous)
Epithelium
Lamina propria
Skin (Stratified Squamous)
Epidermis
(Epithelium)
Dermis
(Connective
tissue)
Trachea (Pseudostratified Epithelium)
Epithelium
Cilia
Ciliated cells
Goblet cells
Basal lamina
Lamina propria
Ureter (Transitional Epithelium)
Epithelium
Lumen
Basal lamina
Lamina propria
Basal Lamina
•
•
Next to epithelia an acellular sheet like structure is the Basal Lamina.
Component Layers & Constinuent Macromolecules:
A. Component Layers
Lamina lucida
Lamina densa
B. Constituent Macromolecules
Lamina lucida (Laminin that binds to cell surface integrins, collagen IV)
Lamina densa (Type IV Collagen)
Basement Membrane:
Basal lamina accompanied by reticular lamina (Type III Collagen) is called the
basement membrane.
Functions:
Forms sieve-like selective barrier between the epithelia & connective
tissue.
Aids in cell organization, cell adhesion & maintainence of cell
shape.
Has a role in maintaining specific cell function.
Helps guide migrations of cells during development and regeneration of
injured tissue
Polarity & Specialization of Epithelial Cells
A.
B.
C.
D.
Specialization of the Apical Surface:
1. Microvilli (Enterocytes & Proximal convoluted tubule cells))
2. Cilia (Trachea, Bronchus etc.)
3. Stereocilia (Epididymis)
4. Flagella
Specialization of the Lateral Surfaces:
1. Zonula occludens (Tight junctions)
2. Zonula adherens (Intermediate junctions)
3. Macula adherens (Desmosomes)
4. Gap junction (Nexus)
Specialization of the Basal Surface:
1. Basal lamina
2. Hemidesmosome
3. Sodium-potassium ATPase
Intracellular Polarity:
Cell Junctions
Microvilli
Zonula occludens
Zonula adherens
Terminal web
Macula adherens
Gap junction
Nucleus
Hemidesmosome
Mucous Membranes
• Components of Mucous Membrane:
1. Epithelium
2. Basement membrane
3. Lamina propria
Mucous Membrane
Epithelium
Basal lamina
Lamina propria
Serous Membranes
A. Components of Serous Membrane:
1. Epithelium called mesothelium
2. Basement membrane
3. Submesothelial connective tissue layer
1. Protection from:
Functions of Epithelia
Mechanical trauma
Dehydration
Pathogens
2. Secretion of:
Hormones, milk, sweat etc.
Enzymes, HCl, glycoproteins,
Mucous & serous products
3. Lubrication of:
Contents of GI tract
Fetus in birth canal
Joints
4.
5.
6.
7.
Filtration of wastes: (Urine)
Absorption of food: (Aminoacids, Glucose, Fatty acids)
Neuroepithelium:
(Taste, Smell, Hearing)
Reproduction:
(Germ cells)
Major Types of Epithelial Cells
A.
Epithelial Cells Specialized for Transport:
1. Ion-transporting cells (Kidney tubules, Gall bladder etc.)
2. Cells that transport by pinocytosis (Endothelial cells of
blood capillaries
B. Absorption: (Enterocytes, Proximal convoluted tubule cells)
C. Secretion:
1. Protein-secreting cells (Acinar cells of pancreas, Hepatocytes)
2. Polypeptide-secreting cells (APUD cells)
3. Mucous cells (Goblet cells)
4. Serous cells (Acinar cells of pancreas & secretory cells of parotid
salivary glands.
5. Steroid-secreting cells (Adrenal cortex, Leydig cells etc.)
D. Contractile Epithelial Cells: (Myoepithelial cells of glands)
GLANDS
A.
B.
Exocrine & Endocrine Glands:
Classification of Exocrine Glands:
1. By structure:
a) Number of cells
b) Duct system
c) Secretory portion
2. By secretory product
a) Mucous secretion
b) Serous secretion
c) Seromucous secretion
3. By mode of secretion
a) Merocrine
b) Apocrine
c) Holocrine
Unicellular
Multicellular Simple tubular Coiled tubular Branched
Simple branched
Simple acinar
Compound tubular Compound
tubulo-alveolar
Salivary Glands
Mucous acini
Serous acini
Mode of Secretion
Active transport Merocrine
Apocrine
Holocrine
Endocrine
Connective Tissue
Fat
Fat cells
Tanden
Fibroblasts
Bone
Osteocytes
Connective Tissue
• Is one of the 4 basic tissues of the body.
• Structurally it is made up of cells and large
amount of intercellular space containing
extracellular matrix.
• Matrix is the dominating component of this tissue.
• It forms framework, connecting, supporting and
packing tissue of the body.
• It also plays a dynamic role in the development,
growth and homeostasis of other tissue types.
Connective Tissue
Loose connective tissue
Dense connective tissue
Fibroblasts
Extracellular matrix
Epithelial tissue
Mammary Glands
Composition
• Cells
• Extracellular matrix
Types of Cells in Loose
Connective Tissue
1. Residents:
Fibroblasts
Macrophages
Reticular cells
Mesenchymal cells
2. Visitants:
Mast cells
Plasma cells
Leukocytes
Fat cells
Melanocytes
Loose Connective Tissue
Macrophage
Adipocyte
Elastic fibers
Capillary
Neutrophil
Plasma cell
Mast cell
Lymphocyte
Fibroblast
Collagen fibers
Fibroblast (Ultrastructure)
Nucleus
Rough ER
Collagen
Extracellular matrix
Collagen Producing Cells
1.
2.
3.
4.
5.
Fibroblast-More than one type of collagen
Chondroblast- Type II collagen
Osteoblast-Type I
Reticular cell- Type III
Smooth muscle-Type I & III
Extracellular Matrix
• Extracellular matrix (Fibers & Ground substance) is synthesized and
secreted mainly by the fibroblasts & the fibers are assembled in the
extracellular space.
• Fibers
Prime function is support & plays strengthing role in
• Ground substance
Functions are
1. Acts as a molecular sieve & stops the spread of noxious substances
2. Plays very important role in cellular nutrition & waste removal
3. Plays a vital role in aging. Its amount diminishes with age and
wrinkles start appearing.
Fiberous Components
Connective tissue fibers are long, slender protein polymers
that are present in variable proportions in different types of
connective tissue.
In many cases the predominant fiber type is responsible for
conferring specific properties on the tissue.
•
Collagen Fibers:
•
Elastic Fibers:
•
Reticular Fibers:
Collagen Fibers
Collagen Fibers:
Most abundant protein in the body.
Synthesis & assembly:
Collagen typesType I- most abundant & occurs in loose and dense connective
tissue & bone.
Type II- occurs in cartilage.
Type III- occurs in hematopoitic tissues.
Type IV- occurs in basal laminae & does not form fibers or fibrils.
Type V- in placental basement membranes & blood vessels.
Type X- around hypertrophic, degenerating chondrocytes of the
growth plate where bone formation is to occur.
Synthesis of Collagen
Collagen’s main amino acids
Glycine (34%)
Fibroblast
Intracellular
Extracellular
Proline (12%)
Hydroxyproline (10%)
Procollagen (Triple-helical units)
Procollagen peptidase
Tropocollagen
Collagen fibril
Collagen fiber
Ground Substance
Proteoglycans:
They are made up of a core protein to which glycosoaminoglycans
(GAGs) are attached. GAGs are polysacharides that contain
aminosugars.
GAGs-Chondroitin sulphate, Dermatan sulphate, Keratan sulphate
& Heparin sulphate.
Hyaluronic acid is a GAG but do not form proteoglycans.
Matrix viscosity and rigidity are determined by the amount and
types of GAGs, their association with the core protein to form
proteoglycans, GAG-fiber association, and GAG-GAG associations.
Glycoproteins:
Fibronectin-mediates the attachment of cells to the extracellular
matrix.
Laminin-a component of basal laminae that mediates the attachment
of epithelial cells.
Tissue fluids:
Salts:
Connective Tissue Types
A. Connective Tissue Proper:
1. Loose connective tissue
2. Dense connective tissue
a) Dense regular connective tissue
b) Dense irregular connective tissue
B. Reticular connective tissue:
C. Elastic connective tissue:
D. Mucous connective tissue:
Connective Tissue Proper
A. Connective Tissue Proper:
1. Loose connective tissue (lamina propria)
2. Dense connective tissue
a) Dense regular connective tissue (Tendon, ligament)
b) Dense irregular connective tissue (Dermis, organ capsule)
Loose CT
Dense CT
Elastic Connective tissue
Elastic fibers consist of an amorphous protein called
elastin and numerous protein microfibrils embedded in it.
Diameter range 0.1-10um.
Elastic fibers are collected in thick, wavy, parallel bundles
& seperated by loose collagenous tissue with fibroblasts.
Ground substance is sparse.
Elastic connective tissue provides flexible support.
Predominates in the ligamentum flava of the vertebral
column & the suspensory ligament of the penis.
Reticular Connective Tissue
These fibers look very similar to collagen but are thinner
than them (0.1-1.5um).
More highly glycosylated.
Form delicate silver-staining network instead of thick
bundles.
Composed mainly of type III collagen and some
glycoprotein.
These fibers are covered by long processes of the reticular
cells.
There is very little ground substance.
Reticular connective tissue supports motile cells & filters
body fluids.
It is found mainly in hematopoietic tissue (bone marrow,
spleen and lymph nodes).
Reticular Connective Tissue
Reticular cell Nu
Reticular fibers
Reticular cells
Lymphocyte
Lymph Node
Mesenchyme
Mesenchyme is embryonic connective tissue.
Its stellate and fusiform cells (mesenchymal
cells) are derived from mesoderm.
They give rise to all the connective tissue of
of the body.
These are multipotential cells and persist in
adults to give rise to new generations of connective
tissue cells especially during wound healing, bone
repair and tissue fibrosis.
Mesenchymal Tissue (Embryo)
Neural tube
Mesenchyme
Somite
Notochord
Neural tube
Extracellular matrix
Mesenchymal cells
Histophysiology
A. Functions:
1. Support.
2. Defense.
a) Physical
b) Immunologic
3. Repair.
4. Storage.
5. Transport
B. Edema:
C. Hormonal Effects:
D. Nutritional Factors:
E.
Collagen Renewal:
Special Types of Connective
Tissues
•
•
•
•
Adipose tissue
Blood & lymph
Cartilage
Bone
Blood
White Blood Cells (Granulocytes)
Neutrophil
Eosinophil
Basophils
Functions:Neutrophils act as first line of defense in infections.
Eosinophils respond to allergic states & parasitic infection
Basophils release heparin & histamine
Defense System
ADAPTIVE DEFENSES
INNATE DEFENSES
(Requires immunization)
(Do not require immunization)
Physical barriers
(Skin, mucous membranes)
Chemical barriers
(Low pH, Mucous)
Soluble factors
(Lysosomes, Interferons,
Acute phase proteins,
Complements)
Cytotoxic
T lymphocytes
Help
B lymphocytes
Facilitates
CELLS
(Macrophages, Granulocytes)
Directly kill infected cells
Facilitate
ANTIBODIES
Delayed response
Fast response
Limited Flexibility
Non-specific
No memory
Highly flexible
Highly specific
Memory, lasting immunity
Mast Cells
Mast cells
Functions:Produce heparin, an anticoagulant
Produce histamine to render blood vessels permeable
Monocytes
Nucleus
Cytoplasm
RBC
Nucleus
Cytoplasm
Phagocytized
RBC
Nucleus
LYMPHOCYTES
B Lymphocytes deliver antibodies-mediated immune response
T lymphocytes deliver cell-mediated immune response
Natural killer cells kill tumor & nonself cells
Plasma Cells
Plasma cells
Lymphocyte
Plasma cells produce antibodies to fight the infections
Immunoglobulins
IgG, IgA, IgM, IgE & IgD
Macrophage
Macrophage
Functions:Phagocytose, process & present antigens to lymphocytes
Act as scavengers etc.
Unilocular Adipose Tissue
Adipocytes
Nucleus
Multilocular Adipose Tissue
Cartilage
Perichondrium
Chondroblasts
Chondrocytes
Lacuna
Cartilage matrix
Isogenous group
of chondrocytes
Primary Bone
Periosteum
Osteoblasts
Osteocytes
Bone matrix
Bone trabecula
Nervous Tissue
Cerebellum
Cortical neurons
Spinal cord
Motor neurons
Spinal ganglion
Sensory neurons
Divisions of the Nervous System
• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)
• Autonomic Nervous System (ANS)
Nervous System
General Features
• Two Classes of Cells:
1. Neurons
2. Supporting cells
• Impulse Conduction:
• Synapses:
• Divisions of the Nervous System:
• Embryonic Development of Nervous Tissue:
• Aging and Repair:
• Meninges:
• Blood-Brain barrier:
Cells of the Nervous Tissue
Two Classes of Cells:
1. Neurons.
2. Supporting, neuroglial or glial cells.
Neurons
•
•
•
•
Cell Body
Dendrites
Axon
Classification of Neurons
Neuron
Neuromuscular Junction
Skeletal muscles
Axon
Motor end plate
Neuron
Blood capillary
Glial cells
Dendrites
Nissl bodies
Axon hillock
Nucleus
Nucleolus
Myelinated axons
•
Neuron
(Cell
body)
Cell Body:
-It is also called soma or perikaryon
-It is the synthetic & trophic center of cell
-It can receive signals from axons of other
neurons through synaptic contacts on its
cell membrane and relay them to its axon
-Nucleus usually large, central, spherical
and euchromatic
-Nucleus with prominent nucleolus
-Cytoplasm contains many organelles like
mitochondia, lysosomes etc.
-Cytoplasm has abundant free polyribosomes &
rough endoplasmic reticulum, appears
as basophilic purplish-blue clumps called
Nissl bodies
-Well developed Golgi to pack & often glycosylates
neurotransmitters in neurosecretory, or synaptic vesicles
-Abundant neurotubules (microtubules) & neurofilaments
(intermediate filaments) in soma, dendrites & axon
Neuron (Dendrites)
• Dendrites:
-Extensions of cell body, specialized to
increase the surface area for incoming
signals
-Synaptic contacts are made on them
-Some synaptic sites on them look like
sharp projections called dendritic spines
gemmules
-Proximal ends has some Nissl bodies
• Axon:
Neuron (Axon)
-One axon per neuron, its cytoplasm called axoplasm & its plasma
membrane, the axolemma.
-A complex cell process (uniform diameter) carries impulses away
from the soma.
-The part of the cell body where axon exits the soma is called the axon
hillock and it lacks Nissl bodies.
-Axon can be myelinated or unmyelinated.
-Myelin sheath in CNS is provided by the oligodendrocyte , while in
PNS by the Schwann cell
-Axon diameter & myelin thickness determines the speed of nerve
impulse. Internode (Myelin –covered) & Node (without myelin)
-Some axons have branches called collaterals.
-Terminal branching of axon is called terminal arborization.
-Each branch ends as a bulb-like sac called terminal bouton,
each bouton contains many mitochondria & neurosecretory vesicles.
Specialized region of plasma membrane of bouton that take part in
the formation of synapse is called as presynaptic membrane.
Nerve (Myelinated axons)
Perineurium
Endoneurium
Nodes of Ranvier
Axon
Myelin
Axon
Myelinated Axon (E.M.)
Neurilemma
Myelin
Axoplasm
Node of Ranvier
Synapses (Chemical)
Synapses are specialized junctions by which a stimulus is transmitted
from a neuron to its target cell.
1. Presynaptic Membrane:
This is part of plasma membrane of terminal bouton.
2. Synaptic Cleft:
Fluid-filled space between pre and post synaptic membranes.
3. Postsynaptic Membrane:
This is part of plasma membrane of the target cell. It is thicker
than presynaptic membrane due to the presence of receptors for
neurotransmitters. When enough receptors are occupied,
hydrophilic channels open, resulting in depolarization of the
postsynaptic membrane. Neurontransmitter like acetylcholine
that remains in the synaptic cleft is degraded by
acetylcholinesterase.
This removal of extra acetylcholine allows postsynaptic
mambrane to reestablish its resting potential and prevents
continuous firing of the postsynaptic neuron in response to a
single stimulus.
Types of Synapses
• Axodendritic (Between an axon & a
dendrite)
• Axosomatic (Between an axon & a cell
body)
• Dendrodendritic (Between dendrites)
• Axoaxonic (Between axons)
Neuron (Types)
• Based upon Configuration of cell processeses:
Multipolar
(Motor neurons of spinal cord)
Bipolar
(Retina, olfactry mucosa)
Unipolar
(Photoreceptors, rods & cones of retina)
Pseudounipolar
(Sensory neurons of dorsal root ganglia)
• Based upon Cell size:
Golgi type I
(Motor neurons of spinal cord)
Golgi type II (Interneurons of spinal cord)
• Based upon Function
Motor neurons
(Multipolar neurons of ventral horn etc.)
Sensory neurons (Pseudounipolar neurons of dorsal root ganglia)
Interneurons
(Golgi type II neurons)
• Based upon Neurotransmitter released
Cholinergic neurons (Most somatic motor neurons)
Adrenergic & noradrenergic neurons (Postganglionic sympathatic
neurons)
Dopaminergic (Some neurons of hypothalamus)
GABAergic (Some neurons of the brain)
Types of Neurons
Unipolar
Bipolar
Pseudounipolar
Multipolar
Supporting Cells
• Provide structural and functional support to
neurons.
• Take part in the formation of blood-brain
barrier, thus monitoring the passage of
materials from blood to neurons.
Supporting cells of CNS
1. Astrocytes:- (Blood-Brain Barrier)
a) Protoplasmic astrocytes
b) Fibrous astrocytes
2. Oligodendrocytes:- (Myelin to axons in CNS)
3. Ependymal cells:- (Produce the CSF)
4. Microglial cells:- (Macrophages of the nervous system)
Supporting Cells of PNS
1. Schwann cells:
A Schwann cell may envelop segments of several unmyelinated
axons or provide a segment of a single myelinated axon with its
myelin sheath. Each mylinated axon segment (internode) is wrapped
around by layers of a Schwann cell process with most of its
cytoplasm squeezed out. This multilayered Schwann cell plasma
membrane (mainly of phospholipids) is called myelin. The gaps
between myelin sheath segments are the nodes of Ranvier.
2. Satellite cells:
Each neuron outside the CNS is surrounded by a single layer of
cells, called satellite cells.
Aging and Repair
• A neuron is a terminally differentiated cell.
• And is incapable of undergoing mitosis.
• Aging neurons accumulate more of lipofuscin
pigment.
• Neurons lost through injury or surgery cannot be
replaced.
• If the cell body remains intact, the injured axon can
regenerate itself.
• If stimulated by injury, supporting cells, unlike
neurons, can divide.
Blood-Brain Barrier
• Components of the barrier:
1. Endothelial cells of continuous type
capillaries (Tight junctions)
2. Basal lamina
3. Cytoplasmic processes of astrocytes.
Blood-brain Barrier
Peripheral nerve
Peripheral Nerve (Fascicle)
Perineurium
Endoneurium
Myelinated axons
Response of Nerve Tissue to Injury
A. Damage to the Cell Body:
A neuron is a terminally differentiated cell & is unable to divide. So
damaged or dead neurons can’t be replaced.
B. Damage to the Axon:
1. Degenaration:- Distal to the site of injury, axon & myelin
degenerate. Within 2-3 days, they are removed & these clear
endoneurial channels are occupied by Schwann cells. Proximal to
the site of injury, retrograde degeneration of axon goes up to 2
internodes, then injured axon is sealed. Cell body also undergoes
changes in response to the injury. The Nissl bodies disappear
(chromatolysis) & nucleus moves to the periphery. (2 Weeks)
2. Regeneration:- Begins at 3rd week, Nissl bodies reappear,
protein synthesis starts. Axon’s proximal stump gives off a
number of small processes called neurites. One of these enters
and grows in an endoneurial channel and synaptic contacts are
remade with the target cell. The target cell or organ deprived of
innervation often atrophy.
Nerve Injury & Recovery
A
Cell body
B
C
D
E
Nissl bodies
Axon
Schwann cells
Motor end plate
Muscle
Before injury
2 weeks
3 weeks
3 months No healing
Muscle Tissue
Cardiac muscle
Skeletal muscle
Visceral muscle
Basic Properties of Muscle Tissue
1. Excitability- ability to respond to a stimulus
2. Conductivity- ability to propagate a limited response
3. Contractility- ability to shorten
4. Relaxability- ability to relax (return to original shape
after contraction)
IC Disc
Nucleus
Cardiomyocyte in Longitudinal Section
Endomysium
Capillary
Nucleus
Myofibrils
Cardiomyocyte
Purkinje Cell
In Cross Section
Smooth Muscle
Skeletal Muscle
Cardiomyocyte (Long. Section)
Endomysium
Cardiomyocytes
Nucleus
Cardiomyocytes (Cross section)
Cardiomyocytes
Nucleus
Myofibrils
Endomysium
Capillaries
Comparison Of Types Of Muscles
Property
Location
Skeletal Muscle
Muscles of skeleton Heart
Cell size/shape Long; cylindrical
Nuclei
Cardiac Muscle Smooth Muscle
Visceral organs
Short, branched Variable, fusiform
Many; peripherally Single; centrally Single: central
located
located
Striations
Z lines
Yes
Yes
T tubules &
Sarcoplasmic
reticulum
Triads at A-I
junctions
Cell junctions None
Yes
N
Yes
Dense bodies
Diads at Z line Caveolae replace T
tubules; sparse
Intercalated disks
(Adherens,
Nexi (Gapjunctions)
occludens & nexi)
EM of Cardiac muscle (IC disc)
Macula adherens
Gap junction
Fascia adherens
EM of Skeletal muscle