Platelet cell

 platelets = small plate; thrombo=clot; cytes =
cells
 Platelet are smalllest blood cells, colourless,
nonnucleated, round or oval, flattened, disk-
shaped structures
 Cytoplasm =Golgi apparatus , endoplamic
reticulum, few mitochondria, microvsicles,
glycogen, lysosomes

 Platelets, also called thrombocytes (thromb- + -cyte,
"blood clot cell")Platelets are produced in the bone
marrow.
 Platelets are produced from very large bone marrow cells
called megakaryocytes.
 As megakaryocytes develop into giant cells, that results in
the release of over 1,000 to 3000 platelets per
megakaryocyte.
 Platelets have no cell nucleus.
 2–3 µm in greatest diameter.
 Megakaryocyte and platelet production is regulated by
thrombopoietin, a hormone in the kidneys and liver.

 Each megakaryocyte produces between
1,000 and 3,000 platelets during its lifetime.
 An average of 1011 platelets are produced
daily in a healthy adult.
 average life span of circulating platelets is 8
to 9 days
 In adults 1.5 -4 lakhs/mm3 of blood.

 On a stained blood smear, platelets appear as dark purple
spots.
 First, platelets attach to substances outside endothelium
 Second, they change shape, turn on receptors and secrete
chemical messengers
 Third, they connect to each other through receptor bridges.
 platelet granules. Alpha granules contain clotting mediators such
as factor V, factor VIII, fibrinogen, fibronectin, platelet-derived
growth factor, and chemotactic agents. Delta granules, or dense
bodies, contain ADP, calcium, serotonin, which are platelet-
activating mediators. -
 Platelets have d-granules that contain serotonin, adenosine
diphosphate (ADP), and Ca2


 The main function of platelets is to contribute to hemostasis: the
process of stopping (arrest) bleeding endothelium
 Phagocytosis of small particles (carbon)and (viruses)
organisms.
 Storage and transport (Serotonin )of chmicals. (Heparin)
 platelet provided factor 3 (platelet phospholipids ) process of
clotting blood.
 Serotonin released by platelet observed immediately after
vascular injury.
 Hemostatic plug is formed by platelet and is their primary
function.(stops bleeding).
 Platelet have growth factor repair of the damaged vassel wall.

 Platelet activation causes its membrane surface
to become negatively charged that negatively
charged phospholipids from the inner to the
outer platelet membrane surface.
 These phospholipids then bind the tenase and
prothrombinase complexes, two of the sites of
interplay between platelets and the coagulation.
 Calcium ions are essential for the binding of
these coagulation factors.

 Symptoms of a Low Platelet Count
 red, purple
 a rash with small red or purple dots
 nosebleeds
 bleeding gums
 bleeding from wounds that lasts for a prolonged period or
doesn’t stop.
 heavy menstrual bleeding
 blood in the stools or Gastrointestinal bleeding
 blood in the urine
 In more serious cases
 blood in the urine
 blood in the stool
 bloody or very dark vomit

 Increased Numbers Of Platelets
thaThrombocytosis
 Decreased Numbers Of Platelets
Thrombocytopenia

 aplastic anemia
 a vitamin B-12 deficiency
 an iron deficiency
 viral infections, including HIV, Epstein-Barr virus, and
chickenpox
 exposure to chemotherapy, radiation, or toxic chemicals
 consuming too much alcohol or Alcohol toxicity, ethanol abuse
 Leukemia
 an autoimmune disorder
 Pregnancy
 Viral, bacterial, and rickettsial infections
 Antiplatelet antibodies

 Idiopathic thrombocytopenia (ITP), also known as immune
thrombocytopenic is the result of antibody production
against platelets.
 Viral infections such as mononucleosis, hepatitis, HIV or
measles
 Heparin-induced thrombocytopenia (HIT) results in low
platelets when a person who is on or received heparin
therapy develops an antibody.
 Leukemia, lymphoma, or another cancer that has spread
(metastasized) to the bone marrow—people with cancers
after significantly decreased number of platelets.
 Aplastic anemia—a condition in which the production of all
blood cells is significantly reduced
 Long-term bleeding problems (e.g., chronic bleeding from
stomach ulcers)
 Sepsis, especially that caused by a serious bacterial
infection with Gram-negative bacteria.

 Cancer, most commonly lung, gastrointestinal, ovarian, breast or lymphoma
 Anemia, in particular iron-deficiency anemia and hemolytic anemia
 Inflammatory conditions such as inflammatory bowel disease (IBD) or
rheumatoid arthritis
 Infectious diseases such as tuberculosis
 Recovery from significant blood loss such as from trauma or major surgery
 After physical activity or exertion
 Recovery from excess alcohol consumption and vitamin B12 and folate
deficiency
 diabetes mellitus, increased blood lipids or cholesterol levels, increased
platelet levels, and smoking.
 Rheumatoid arthritis
 Renal failure
 Chronic pancreatitis

 1. Platelet counts normally increase at high
altitudes; exercise, trauma, or excitement;
and in winter.
 2. Platelet counts normally decrease before
menstruation and during pregnancy.

 avoiding contact sports
 avoiding activities with a high risk of bleeding.
 limiting alcohol consumption
 stopping or switching medications that affect
platelets, including aspirin and ibuprofen
 blood or platelet transfusions
 changing medications that are causing a low
platelet count
 corticosteroids to block platelet antibodies
 drugs that suppress your immune system
 a splenectomy, or the surgical removal of the
spleen

Platelet cell

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Platelet cell