final 2nd semester Flashcards
bone marrow, structure and tissue composition. features of blood supply
1-Yellow bone marrow
The yellow bone marrow is located in the hollow centers of the long bones such as in the legs and in the arms, largely consists of
fat cells. The yellow bone marrow turns into red marrow in
emergencies such as blood loss or anaemia.
2-The red bone marrow is found mainly in the flat bones, such as the hip bone, breast bone, skull ,ribs, vertebrae and shoulder
blades, and in the cancellous material at the epiphyseal ends of the long bones such as the femur and humerus.
*Structure of red bone marrow Red bone marrow: is composed of 3 main components:
1: stroma: consists of a three layers of reticular tissue, it contains reticularcells and reticular fibers, macrophages
2: hematopoietic cords : formed by the myeloid tissue and contains the myeloid and lymphoid cells at different stages of their
development..
3: sinusoidal capillaries (sinusoids):are a system of interconnected blood vessels. They are formed by a continuous layer of
endothelial cells.
11-thymus. structure of the tissue composition. features of blood supply. Hemato-thymic barrier.
1-The thymus is a specialized primary lymphoid organ of the immune system.it is located in the superior mediastinum in front of
the heart.2-It is covered with connective tissue capsule, from which into the depth of the thymus connective tissue septa depart
and divide it into lobules -3 lobule of the thymus is distinguished into cortex and medulla.
In the cortex there are3 zones:1-Subcapsular zone – contains T-lymphoblasts, which migrate into this zone from the red bone
marrow. Epithelioreticular cells of this zone are called nurse cells. They excrete hormones: thymosin, thymalin, thymopoietin,
which contribute the reproduction and differentiation of T-lymphoblasts.2-The thickness of the cortex:The structural unit of this
zone is Clark’s follicle. It consists of. 1- Dendritic cell 2-Macrophage 3-T-lymphocytes
Dendritic: cells of this zone select T-lymphocytes, which react against self antigens and launch their apoptosis T-lymphocytes.
Are located Between epithelioreticular cells
3- Premedullary zone – contains pre-T-helpers (CD4+), pre-T-killers (CD8+), interdigitale, dendritic cells and macrophages.
2-medulla:is constituted by recirculating T-lymphocytes. In the centre of the medulla there are Hassal’s corpuscles. They are
formed by stratified on each other epithelio reticulocytes. It is suggested that they produce interleukins :Hemato-thymic barrier: The barrier protects T-lymphocytes from a contact with antigens, which are in blood Its components-
1-Endothelium of a capillary and its basal membrane 2-Perivascular connective tissue space
3-Epithelioreticular cells with their basal lamina.
These layers provide the protection to the developingimmature T cells and separate them from matureimmunocompetent
lymphocytes circulating in the bloodstream.
-Blood supply: 1-Internal thoracic artery and 2-inferior thyroid arteries
12-spleen. structure of the tissue composition. features of blood supply. Function of the organ
—The spleen – it is covered with C.T capsule, which is lined with mesothelium outside. From the capsule into the depth of the
spleen septa depart. The capsule and septa contain smooth muscle cells. The basis of the spleen is constituted by reticular cells,
in cells of which there is a pulp of the spleen. The parenchyma is represented by white and red pulp.white pulp: is represented by lymphoid nodules, Through each lymphoid nodule the central artery goes. A nodule has 4 -1
zones: 1.the periarterial zone – localizes around the central artery, contains T-lymphocytes and interdigitating cells. 2. Germinal
centre– contains B-lymphocytes, plasmatic cells and macrophages. 3. The mantle zone – contains B- and T- lymphocytes,. 4. The
.marginal zone – contains B- and T- lymphocytes and macrophag
-Red pulp:is represented by blood cells, predominantly by erythrocytes, which are located in sinusoid vessels and in reticular -2
.tissue. Numerous erythrocytes give red color to the red pulp
-Blood supply: 1-splnic artery passes into trabecular artery then into puloary and central arteries 2-cenatral artery split on central
arterioles –then penicillar arterioles turn into capillaries then they turn into venous sinuses (this is closed circulatory system)
if blood from capillaries goes into reticular tissue its called (open circulatory system)
Venous outflow throught 1-pulpary venule then 2-trabecular vien then splenic veins
-Function:1. Antigen-dependent differentiation of T- and B- lymphocytes. 2. Protective
.Hematopoietic. 4. Blood depot. 5. The destruction of aging erythrocytes and trombocytes .3
32-liver, the structure of the classical lobule of the liver. liver function
-The liver is a large, meaty organ that sits on the right
side of the belly. Weighing about 3 pounds, the liver is reddish-brown in color and feels rubbery to the touch. The liver has two
large sections, called the right and the left lobes
-classic liver lobule: is hexagonal in section. In the centre of the liver lobule there is a central vein. At the corners of the lobules
there are the portal triads. The blood flow is directed from periphery to the center, and bile - from the center to periphery
-function:1-detoxification of many drugs and toxins;2- production of bile required for emulsifying fats.3- storage of vitamins (A,
D, K) and iron. 4- volume reservoir for blood.
33- pancreas, structure. liver function :
—The pancreas is both an exocrine and endocrine gland. It consists of: the clusters of cells
of the endocrine tissue known as islets of Langerhuns. These cells produce insulin, glucagon and a number of other
hormones.The pancreas is covered by a thin capsule of connective tissue.
-The exocrine pancreas: secretes digestive enzymes that can digest most food substances:(The exocrine pancreas)constitutes
main part of gland (97%). It is compound :serous tubuloacinar gland, which consists of: 1-secretory portion (acini), 2-duct
system.
-Acini have elongated shape narrow lumen, are composed of 2 types of cells:
1-Acinar cells: are highly polarized, and consists of rough endoplasmic reticulum,
2- centroacinar cells: are small, flattened with pale cytoplasm, are situated in the centre of acinus. Endocrine pancreas
-The endocrine pancreas: is the islets of Langerhans and they are formed of 75% B (beta)-cells: are most numerous, bluestained, form the central part of the islets, secrete hormone insulin.
the adrenal glands. sources of development. the cellular structure. the structure of the cortical and medulla.
—the adrenal glands are paired organs located near the upper pole of the kidneys.Each gland is covered by connective tissue
capsule and has 2 parts:1-outer cortex :is subdivided into 3 zones: 1. outer zona glomerulosa; 2. middle zona fasciculate 3.
inner zona reticularis.
1) . Zona glomerulosa: consists of columnar cells arranged in rounded groups. The cells have light basophilic cytoplasm.Cells of
zona glomerulosa secrete mineralcorticoid hormones, which function is regulation of sodium and potassium homeostasis and
water balance. Principal hormone, aldosterone, acts on the distal tubules of the nephrons in the kidney
2) . Zona fasciculate: is the thickest zone. It consists of narrow cords of polyhedral cells (one or two cells thick). The cytoplasm of
the cells is rich in smooth endoplasmic reticulum and lipid droplets Zona fasciculate produces glucocorticoids ,mainly cortisol
and corticosteron. These hormones regulate the carbohydrate, protein and lipid
3) . Zona reticularis: consists of cells disposed in irregular cords that form an anastomosing network. These cells are smaller
than those of the other two layers. Lipofuscin pigment granules in the cells are large and umerous .Zona reticularis is responsible
for secretion of small quantities of androgens and glucocorticoids. Zona reticularis is under control of ACTH of
adenohypophysis.
—2-Adrenal medulla : The adrenal medulla is composed of polyhedral chromaffin cells arranged in cords or clumps and supported
by reticular fiber network .The adrenal medulla consists of two types of cells:
1- epinephrine : secreting cells, which have smaller, less-electron-dense granules
2- norepinephrine :secreting cells, which have larger, more electron- dense granules
42- skin, features of structure and regeneration.
Skin consists of 3 layers:
1-epidermis 2-dermis 3-subcutaneous layer
(hypodermis)
-1-epidermis: consists of stratified squamous keratinised epithelium and has 5 layers:
1- Stratum basale: consists of single layer
of basophilic columnar cells (keratinocytes) resting on the basal lamina at the dermal-epidermal junction.
2- Stratum: spinosum
consists of polygonal cells joined to one another by cytoplasm processes. Mitosis occurs in both the above layers and such two
layers together are called (stratum germinativum) .
3-Stratum: granulosum consists of 1 or 5 layers of flattened polygonal cells.
These cells contain kerotohyalin granules.
4- Stratum lucidum: is thin layer of flattened eosinophilic cells. The cells are died and contain droplets of eleidin, precursor of
keratin
5-Stratum corneum consists of: 15-20 layers of flattened anucleate keratinized cells whose cytoplasm is filled with scleroprotein,
keratin. The most superficial cells are continuously lost and are replaced by proliferation of cells that arise from mitotic activity
in stratum germinativum
-2-dermis: is connective tissue layer containing blood and lymphatic vessels, and nerves of the skin. It also contains hair follicles,
sweat and sebaceous glands -dermis contains 2 layers:
1-superficial (papillary layer): 1-thin papillary layer is composed of loose connective tissue, delicate collagen network contains
type 1 and 3 collagen molecules, elastic fibers form irregular network.
2-deeper (reticular layer): is thicker, composed of irregular dense connective tissue. This layer contains thick and irregular
bundles of mostly type I collagen and rough elastic fibers. This elastic network is responsible for the elasticity of the skin. The
collagen and elastic fibers form regular lines of tension in the skin, called Langer’s lines. Skin incisions made parallel to Langer’s
lines.
-3-hypodermis consists: of loose C.T that binds the skin to the adjacent organs, making it possible for skin to slide over
them.contains fat cells that vary in number according to the area of the body, and in size according to the nutritional status of
the individual.
glands of the skin, structure and histophysiology.
Sweat glands: produce sweat excretion these glands help in temperature
regulation by sweating.There are 2 types of sweat glands:
1-merocrine and 2-apocrine.
-1-The merocrine sweat glands :are present
in the skin of all parts of the body. They are simple, coiled tubular glands whose ducts open at the skin surface. The sweat gland
consists of 2 parts:1-secretory portion: lies deep in the dermis, lined by single cuboidal epithelium. Myoepithelial cells surround
secretory cells. 2-ducts: are lined by 2 layers of dark cuboidal cells.
-2-The apocrine sweat glands: are present in the subcutaneous tissue of the axillary, areolar, and anal regions. Their ducts open
into hair follicles. These glands become fully developed after puberty. The lining of epithelium may be squamous, cuboidal or
columnar. The secretions of apocrine sweat glands are viscous.
—Sebaceous glands:The sebaceous glands are branched alveolar glands of the holocrine type.The secretory portion of the gland
(acini) consists of 2 types of epithelial cells:1-small basal cells: rest on the basal lamina 2- inner cells are larger, more rounded
and filled with lipid.
-urinary tract . the structure of the ureter and bladder.
—-The urinary system: consists of the paired kidneys and ureters, and unpaired bladder and urethra. 1)The kidney: is covered by a
capsule of C.T consisting of collagen, elastic fibers andsmooth muscle cells.-The kidney is divided into:1) an inner
medulla:consists of 10-18 medullary pyramids. From the base of each medullary pyramid the medullary rays penetrate the
cortex. 2) an outer cortex: is the peripheral part lying between the capsule and the bases of renal pyramids.-The cortical tissue
surrounding each medullary pyramid is a renal lobe, and each medullary ray forms the center of a conical renal lobule.
-A part of cortex projects inwards between the renal pyramids and forms the renal columns of Berlin.
-The wall of the ureter and bladder consists of 4 layers: have the same basic histological
structure.1) .-1- Mucosa: consists of :
1. transitional epithelium: having 4 or 5 layers of cells.
2. lamina propria: which consists of loose connective tissue.
-2-. Submucosa : consists of loose connective tissue. 3) . Muscularis : consists of bundles of smooth muscle cells with intervening
connective tissue.4) .Adventitia : consists of loose connective tissue with collagen and elastic fibers. The upper part of the
bladder is covered by serous peritoneum.
-kidney, cortical and medulla of the kidney. nephron as a morphofunctional unit of the kidney
-endocrine apparatus of the kidney.
-Nephron: Each kidney is
composed of 1-4 millions nephrons - the structural and functional units.-Each nephron consists of:
1) dilated portion, the capsule of the renal corpuscle,
2) proximal convoluted tubule,+
3) proximal straight tubule (thick descending limb of Henle’s loop),
4) thin descending limb of Henle’s loop,
5) thin ascending limb of Henle’s loop,
6) distal straight tubule (thick ascending limbs of Henle’s loop),
7) distal convoluted tubule.
–Renal corpuscle Each renal corpuscle consists of:
1) a tuff offenestrated capillaries, the glomerulus, surrounded by.
2) a double walled epithelial Bowman’s capsule
-The parietal layer of the capsule: consists of a simple squamous epithelium surrounded by basal lamina.-The visceral layer of
the capsule: envelops the capillaries of the glomerulus. Between two layers of Bowman’s capsule there is the urinary space,
which receives the fluid filtered through the capillary wall and the visceral layer. And lined by modified celts termed the
podocytes.–The podocytes: have a cell body from which several primary processes arise. Each primary process gives secondary
processes, called pedicels that embrace the capillaries of the glomerulus .Between the pedicles there are little spaces termed
filtration slits. Between the fenestrated endothelial cells of glomerular capillaries and the podocytes is a thick basement
membrane.-The basement membrane: is derived from the fusion of capillary- and podocyte-produced basal laminae.
——- endocrine apparatus —-
-The kidneys produce three important hormones:
1.erythropoietin,
2. calcitriol
3.renin.
–They also synthesize prostaglandins, which affect many processes in the kidneys .
-The juxtaglomerular apparatus: regulates the systemic blood pressure by activation of the reninangiotensin-aldosterone
system. Juxtaglomerular apparatus is the modification of the distal convoluted tubule and the afferent arteriole at the region of
their contact The juxtaglomerular apparatus consists of components:
1. Macula dense: is an area of closely packedspecialised
columnar cells in the wall of the distal convoluted tubule. The cells of macula densa are sensitive to the ionic content and
water volume of the fluid in the tubule (osmoreceptors). If low water volume is detected by these cells, they will produce
molecular signals that promote renin secretion by other ceils of the juxtaglomerular apparatus, called the juxtaglomerular cells.
