HISTOLOGY Flashcards
histology
its the study of tissues and they are arranged into organs
histology synonym
microscopic anatomy
tissue
is the group of cells similar in structure to perform specific function
there are four types of tissue
epithelial tissues
connective tissues
muscular tissues
nervous tissues
tissue that is specialized to form the covering or lining of all internal and external body surfaces except articular cartilage in synovial joint .
epithelial tissue
ectoderm layer
covering external surface
mesoderm layer
lining inner surface of the heart , all body also and lymphatic vessels .
endoderm layer
lining inner surface e.g. lungs , urinary , bladder , exocrine , glands , respiratory system endoderm .
properties of epithelial tissue
- closely packed cells
- no intercellular spaces
- minimal extracellular matrix
- non/vascular // so need a connective tissue support - called // basal lamina or basement membrane
- continuously renewal
subdivided according to three categories
the shape
diversity
metaplasia
shapes of epithelial tissue
squamous
cuboidal
polygonal
columnar
methods of classification
functions
number of layers
- simple
- stratified
simple epithelium
simple squamous epithelium
simple cuboidal epithelium
simple columnar epithelium
simple squamous epithelium
thin, flat plates , they form the lining of cavities such as the blood vessels endothelium , and body cavities mesothelium and bowman’s capsule , usually for exchange of gases
simple cuboidal epithelium
cuboidal in shape . each cell has spherical nucleus in the centre
- found in the ducts of the glands and in the lining of the kidney tubules for secretion
simple columnar epithelium
simple columnar epithelium non ciliated - found in stomach , intestines and gall bladder - specialized for sensory receptors simple columnar epithelium ciliated - found in fallopian tubes of females - for motility
stratified epithelium
stratified squamous epithelium
stratified cuboidal epithelium
stratified columnar epithelium
stratified squamous epithelium
keratinized stratified squamous epithelium
- containing keratin
- the mammalian skin
- for protection against friction and abrasions
nonkeratinized stratified squamous epithelium
- the lining of wet cavity
-
stratified cuboidal epithelium
they protect areas such as ducts of sweat and salivary gland
stratified columnar epithelium
secretion and protection , rare one , found in the conjunctiva
pseudostratified columnar epithelium
ciliated pseudostratified columnar epithelium
non ciliated pseudostratified columnar epithelium
ciliated pseudostratified columnar epithelium
such as those epithelia lining the respiratory passages
non ciliated pseudostratified columnar epithelium
such as those epithelia lining the large ducts of glands
transitional epithelium
it is stratified tissue but it may appear as simple epithelium depending on their status , such as the urinary bladder
the tissue appears stratified when the bladder is empty
the tissue appears as one layer when the bladder is full ‘ it changes from states to another ‘
glandular epithelia
unicellular glandular epithelia
multicellular glandular epithelia
unicellular glandular epithelia
single cells produce mucin , as goblet cells between intestinal columnar epithelium that secrete the mucous
multicellular glandular epithelia
its a secretory unit
they are either
exocrine glands , epithelium derived duct
endocrine glands , do not have ducts
classification of glands according to presence or absence of ducts
exocrine glands
endocrine glands
mixed glands
exocrine glands
glands that secret products into a duct as sweat gland
endocrine gland
ductless glands , secreting hormones , directly into extracellular space then diffuse into the blood or lymph ,, as pituitary glands
mixed glands
as pancreas gland
types of glands according to mode of secretions
merocrine glands
apocrine glands
holocrine glands
merocrine glands
secrete products by exocytosis , as pancreas , and sweat glands .
apocrine glands
accumulation of products then apex of cell pinches off ,, as mammary gland
holocrine glands
accumulation products until cell ruptures ,, as sebaceous gland
types of secretory product of an exocrine gland may also be one of three categories
serous glands
mucous glands
sebaceous glands
serous glands
secrete watery , often protein , rich product .
mucous glands
secrete a viscous product , rich in carbs ,, as glycoproteins .
sebaceous glands
secrete a lipid product or oil .
connective tissue
Connective tissue is incredibly diverse and contributes to energy storage, the protection of organs, and the body’s structural integrity.
Connective tissues are the most abundant, widely distributed, and
histologically variable of the primary tissues. They include fibrous
tissue, adipose tissue, cartilage, bone, and blood. Such diverse tissues may seem to have little in common, but as a rule, their cells
occupy less space than the extracellular matrix. Usually their cells
are not in direct contact with each other, but are separated by expanses of matrix. Connective tissues vary greatly in vascularity,
from rich networks of blood vessels in the loose connective tissues
to few or no blood vessels in cartilage
connective tissue main components
fibres , cells , ground substance
functions of connective tissue
1) binding and supporting,
2) protecting,
3) insulating,
4) storing reserve fuel, and
5) transporting substances within the body.
extracellular matrix
Cells of the connective tissue are suspended in a non-cellular matrix that provides structural and biochemical support to the surrounding cells.
fibroblast
A type of cell found in connective tissue that synthesizes the extracellular matrix and collagen.
Fibrous Connective Tissue
Fibrous connective tissue is the most diverse type. It is also called
fibroconnective tissue. Nearly all connective tissues contain fibers,
but the tissues considered here are classified together because the
fibers are so conspicuous. Fibers are, of course, just one component of the tissue, which also includes cells and ground substance.
Three types of fibers are found in connective tissue
Collagen fibers
Elastic fibers
Reticular fibers
Collagen Fibers
Collagen fibers are the strongest and most abundant of all the connective tissue fibers.
Collagen fibers are fibrous proteins and are secreted into the extracellular space and they provide high tensile strength to the matrix.
Elastic Fibers
Elastic fibers are long, thin fibers that form branching network in the extracellular matrix. They help the connective tissue to stretch and recoil.
Reticular Fibers
Reticular fibers are short, fine collagenous fibers that can branch extensively to form a delicate network.
Connective tissue is divided into four main categories
Connective proper
Cartilage
Bone
Blood
Connective tissue proper has two subclasses
loose and dense
Loose connective tissue is divided into
1) areolar,
2) adipose,
3) reticular,
Dense connective tissue is divided into
1) dense regular,
2) dense irregular,
3) elastic.
Areolar Connective Tissue
These tissues are widely distributed and serve as a universal packing material between other tissues. The functions of areolar connective tissue include the support and binding of other tissues.
It also helps in defending against infection. When a body region is inflamed, the areolar tissue in the area soaks up the excess fluid as a sponge and the affected area swells and becomes puffy, a condition called edema.
Adipose Tissue or Body Fat
Yellow adipose tissue in paraffin section with lipids washed out.
This is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body.
The two types of adipose tissue are white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose tissue is found in specific locations, referred to as adipose depots.
Reticular Connective Tissue
This tissue resembles areolar connective tissue, but the only fibers in its matrix are the reticular fibers, which form a delicate network. The reticular tissue is limited to certain sites in the body, such as internal frameworks that can support lymph nodes, spleen, and bone marrow.
Dense Regular Connective Tissue
This consists of closely packed bundles of collagen fibers running in the same direction. These collagen fibers are slightly wavy and can stretch a little bit.
With the tensile strength of collagen, this tissue forms tendons, aponeurosis and ligaments. This tissue forms the fascia, which is a fibrous membrane that wraps around the muscles, blood vessels, and nerves.
Dense Irregular Tissue
This has the same structural elements as dense regular tissue, but the bundles of collagen fibers are much thicker and arranged irregularly. This tissue is found in areas where tension is exerted from many different directions. It is part of the skin dermis area and in the joint capsules of the limbs.
Elastic Connective Tissue
The main fibers that form this tissue are elastic in nature. These fibers allow the tissues to recoil after stretching. This is especially seen in the arterial blood vessels and walls of the bronchial tubes.
Cartilage
This is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes, and the intervertebral discs.
cartilage is composed of specialized cells called
chondroblasts
cartilage does not contain
blood vessels
Cartilage is classified in three types
1) elastic cartilage,
2) hyaline cartilage,
3) fibrocartilage
Elastic Cartilage
This is similar to hyaline cartilage but is more elastic in nature. Its function is to maintain the shape of the structure while allowing flexibility. It is found in the external ear (known as an auricle) and in the epiglottis.
Hyaline Cartilage
This is is the most abundant of all cartilage in the body. Its matrix appears transparent or glassy when viewed under a microscope. It provides strong support while providing pads for shock absorption. It is a major part of the embryonic skeleton, the costal cartilages of the ribs, and the cartilage of the nose, trachea, and larynx.
Fibrocartilage
This is a blend of hyaline cartilage and dense regular connective tissue. Because it is compressible and resists tension well, fibrocartilage is found where strong support and the ability to withstand heavy pressure are required. It is found in the intervertebral discs of the bony vertebrae and knee meniscus.
macrophage cell
resident and migrant , branched , Macrophages are large, round cells, they are phagocytic, long lived and are found throughout the body , acts as sentinel cells , they have a role in destroying bacteria , protozoa and pinocytosis and phagocytosis
development of macrophages
stem cell develop into a PU1 cell in the bone marrow then into a monocyte in the vessel then into a macrophage in the tissue organs .
neutrophils cell
migrant , unbranched , It contains a multilobed nucleus and plays a phagocytic role in the early stages of acute inflammation
basophils cell
migrant , unbranched , A basic granular cyto-plasm, which secretes vasoconstrictive substances in response to allergens and their secretions resemble excretory cell secretions.
lymphocytes cell
migrant , unbranched , have an oval shape , contains a large nucleus , Unpleasant cytoplasm , its responsible of immune response , There are few numbers in the connective tissue .
acidophil cell
migrant , unbranched , The nucleus consists of two lobes and the cytoplasm is granular and acidic and has a role in resisting infection with parasites.
plasma cells or B cells
migrant , unbranched , It is derived from lymphocytes and produces antibodies against foreign bodies. It has a limited ability to migrate and has a short life span
fibroblast and fibrocytes cell
non/migrant , branched , It is the most common in connective tissue, responsible for the excretion of all complex carbohydrates and fibers into the intercellular substance
chondrocytes cell
non/migrant , branched , It is the cell that secretes the intercellular substance
osteocytes cell
non/migrant , branched , It is called osteogenic tissue in osteogenic tissue. It is found inside capsules and has vials that play the same role as separating the intercellular material.
mesenchyme cells
non/migrant , branched , its origin from mesoderm , it can differentiate to all types of tissue cells , It has long appendages that have large nuclei, which are found in the umbilical cord
mast cells
non/migrant , unbranched , Large, oval-shaped, with a central, round nucleus, the cytoplasm has dark-colored granules filled with histamine, heparin, and serotonin that secrete substances against foreign substances and may cause allergic reactions.
adipose cells or fat cells
non/migrant , unbranched , The fatty substances accumulate in it, and it begins with small fat droplets that combine with each other into a large fat ball and thus the cytoplasm is confined to a thin surrounding layer that lines the cell membrane and pushes the nucleus to one side of the cell, and there are two types in it: a single fat granule, and a multi-granule fat
there are fife composition of bones
cells matrix of collagen fibers ground substance organic 35% , mineral crystals inorganic 65% , small amount of water
development of bone
ossification begins in the week eight and continue , .. osteoblasts are bone-forming cells , osteocytes are mature bone cells , osteoclasts break down and reabsorb bone , either preceded by cartilages and replaced by bones and called cartilaginous bones , also it arises from the connective tissue cells and is called the membranous or cystic bone .
bone types
cancellous , or spongy bone
cortical or compact bone
spongy bone
They are like the inside of the long bones and are as poorly tolerated as the bones of the skull
compact bone
Loading all pressures, such as surrounding long bones and such as the femur
bone functions
support and movement
protection
released as ions into blood as needed
blood cell formation and energy storage
compact bone
consist of units called osteons or Haversian system
the haversian canal contains the bones blood vessels and nerve fibres
osteons are cylindrcal structures that contain a mineral matrix and living osteocytes connected by canaliculi which transport blood
they are aligned paralled to the long axis of the bone , each osteon consist of lamellae , whivh are layer of compact matrix that surround a central canal called the haversian canal ,
volkmann’s canals are any of the small channels in the bone that transmit blood vessels from the periosteum into the bone and that communicate with the haversian canals
blood
blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells
in vertebrates , it is composed of blood cells suspended in blood plasma
it is about 5-6 litters adult male and 4-5 litres in a female .
plasma
it is a protein ‘yellowish liquid’ due to the presence of bilirubin ,
it makes up about 55% of the body’s total blood volume , and contains proteins , enzymes , fats , and coagulation factors , in addition to hormones , antibodies , organic materials , inorganic substances , and swim in the plasma red blood cells , and white , and platelets .
embryonic connective tissue
mucoid connective tissue
mucoid connective tissue
a gelatinous type of connective tissue
supporting the blood vessels of the umbilical cord of the embryonic
umbilical cord is also called Wharton’s jelly
connects foetus to mother
embryonic mesenchyme connective tissue
ground substance containing fibres collagen , star shaped , mesenchymal cells
source of all adult connective tissues
found in embryonic jaw and developing tooth
the formed elements in the blood
The formed elements are cells and cell fragments suspended in the plasma. The three classes of formed elements are the erythrocytes (red blood cells), leukocytes (white blood cells), and the thrombocytes (platelets).
Erythrocytes (red blood cells)
Erythrocytes, or red blood cells, are the most numerous of the formed elements. Erythrocytes are tiny biconcave disks, thin in the middle and thicker around the periphery. The shape provides a combination of flexibility for moving through tiny capillaries with a maximum surface area for the diffusion of gases. The primary function of erythrocytes is to transport oxygen and, to a lesser extent, carbon dioxide
Leukocytes (white blood cells)
Leukocytes, or white blood cells, are generally larger than erythrocytes, but they are fewer in number. Even though they are considered to be blood cells, leukocytes do most of their work in the tissues. They use the blood as a transport medium. Some are phagocytic, others produce antibodies; some secrete histamine and heparin, and others neutralize histamine. Leukocytes are able to move through the capillary walls into the tissue spaces, a process called diapedesis.In the tissue spaces they provide a defense against organisms that cause disease and either promote or inhibit inflammatory responses.
Thrombocytes (platelets)
Thrombocytes, or platelets, are not complete cells, but are small fragments of very large cells called megakaryocytes. Megakaryocytes develop from hemocytoblasts in the red bone marrow. Thrombocytes become sticky and clump together to form platelet plugs that close breaks and tears in blood vessels. They also initiate the formation of blood clots.
Types of white blood cells
Monocytes. They have a longer lifespan than many white blood cells and help to break down bacteria.
Lymphocytes. They create antibodies to fight against bacteria, viruses, and other potentially harmful invaders.
Neutrophils. They kill and digest bacteria and fungi. They are the most numerous type of white blood cell and your first line of defense when infection strikes.
Basophils. These small cells seem to sound an alarm when infectious agents invade your blood. They secrete chemicals such as histamine, a marker of allergic disease, that help control the body’s immune response.
Eosinophils. They attack and kill parasites and cancer cells, and help with allergic responses.
neuron
neuron is the basic unit of the nervous system
neuron structure
It consists of a cell body with a nucleus, filaments known as dendrites and a long fibre known as the axonoften surrounded by a myelin sheath.
nerve
A nerve is a bundle of axons.
Grey matter in the brain and spinal cord consists
Grey matter in the brain and spinal cord consists mainly of brain cells
white matter consists
white matter consists of masses of axons.
Nerve Impulses travel along
Nerve Impulses travel along axons
neurons connect with each other at
neurons connect with each other at synapses.
The nervous system is divided into two parts
the central nervous system and the peripheral nervous system
peripheral nervous system
its consisting of nerves connected to the brain and spinal cord
central nervous system
its consisting of the brain and spinal cord
properties of nervous tissue
Excitability. All cells are excitable—that is, they respond to environmental changes (stimuli). Neurons exhibit this property to the highest degree.
Conductivity. Neurons respond to stimuli by producing
electrical signals that are quickly conducted to other cells at distant locations.
Secretion. When the signal reaches the end of a nerve fiber, the neuron secretes a neurotransmitter that crosses the gap and stimulates the next cell.
nervous tissue
It arises from the outer embryonic layer ‘ectoderm’ except microglia cells that arise from mesoderm layer
what makes the nerve fiber
axon plus telodendrite
dendrites
bring information to the cell body
axons
takes the information away from the cell body
classification of neurons according to structure
anaxonic neuron
multipolar neuron
bipolar neuron
unipolar neuron
classification of neurons according to function
sensory neuron
motor neuron
inter neuron
neuro glia cell or glial cells
are non-neuronal cells in the CNS and PNS
do not produce electrical impulses
maintain homeostasis
provide support and protection for neurons
acting as macrophages , clearing cellular debris and dead neurons from nervous tissue thro the process of phagocytosis
schwann’s cell or neurilemma cell
forms a myelin sheath around neuronal axons
sensory neuron
specialized to detect stimuli such as light, heat, pressure, and chemicals, and transmit information about them to the CNS
motor neuron
send signals predominantly to muscle and gland cells, the effectors. They are called motor neurons because most of them lead to muscle cells, and efferent neurons to signify signal conduction away from the CNS.
inter neuron
They receive signals from many other neurons and carry out the integrative function of the nervous system—that is, they process, store, and retrieve information and “make decisions” that determine how the body responds to stimuli.
unipolar neuron
s have only a single process leading away
from the soma , they are represented by the neurons that carry signals to the spinal cord for such senses as touch and pain
bipolar neurons
have one axon and one dendrite. Examples include olfactory cells of the nose, certain neurons of the retina, and sensory neurons of the ear.
multipolar neurons
they are those, like the preceding, that have one axon and multiple dendrites. This is the most common type and includes most neurons of the brain and spinal cord
Anaxonic neurons
have multiple dendrites but no axon. They communicate locally through their dendrites and do not produce action potentials. Some anaxonic neurons are found in the brain, retina, and adrenal medulla. In the retina, they help in visual processes such as the perception of contrast.
types of nerve fiber
myelinated
unmyelinated
myelinated nerve fiber
they are cells completely surround the Schwann cell
the myelin sheath is a spiral layer of insulation around a nerve fiber , It is about 20% protein and 80% lipid, the latter including phospholipids, glycolipids, and cholesterol.
unmyelinated nerve fiber
they are cells are partially surrounded by Schwann cells
epineurium
is the outermost layer of dense irregular connective tissue surrounding a peripheral nerve . it usually surrounds multiple nerve fascicles as well as blood vessels
perineurium
is the connective tissue sheath that surrounds a bundle of nerve fibers
endoneurium
is the delicate connective tissue network holding together the individual fibers of a nerve trunk
properties of muscular tissue
Excitability (responsiveness). Excitability is a property of
all living cells, but muscle and nerve cells have developed
this property to the highest degree. When stimulated by
chemical signals, stretch, and other stimuli, muscle cells
respond with electrical changes across the plasma membrane.
• Conductivity. Stimulation of a muscle cell produces more
than a local effect. Local electrical excitation sets off a wave
of excitation that travels rapidly along the cell and initiates
processes leading to contraction.
• Contractility. Muscle cells are unique in their ability to
shorten substantially when stimulated. This enables them to
pull on bones and other organs to create movement.
• Extensibility. In order to contract, a muscle cell must also
be extensible—able to stretch again between contractions.
Most cells rupture if they are stretched even a little, but skeletal muscle cells can stretch to as much as three times their
contracted length.
• Elasticity. When a muscle cell is stretched and then
released, it recoils to a shorter length. If it were not for this
elastic recoil, resting muscles would be too slack.
functions of muscular tissue
- maintaining posture
- movement both voluntary and involuntary
- supporting soft tissues without body cavities
- guarding entrances and exits of the body
- maintaining body temperature
types of muscular tissue
- skeletal muscle
- cardiac muscle
- smooth muscle
skeletal muscle
- usually attached to bones
- under conscious control
- striated
cardiac muscle
- wall of heart
- not under conscious control
- striated
smooth muscle
- walls of most viscera , blood vessels , skin .
- not under conscious control
- not striated
structure of a muscle
- thin filaments ‘actin’ and thick filaments ‘ myosin ‘ are found in the myofibrils
- myofibrils are located in muscle fibers ‘cells’
- muscle fibers forming the fascicles
- then a group of fascicles are forming a muscle
Epimysium
is a layer of connective tissue, which ensheaths the entire muscle
perimysium
is the connective tissue that surrounds each bundle of muscle fibers
endomysium
is the connective tissue that covers each single muscle fiber or myofiber or muscle cell.
sarcomere
it is the complicated unit of striated muscle tissue , also its the repeating unit between two Z lines .
synonym of sarcolemma
cell membrane
synonym of sarcoplasmic reticulum
endoplasmic reticulum
sarcoplasm synonym
cytoplasm
sarcosomes synonym
mitochondria
contractile proteins
myosin
actin
