8.2 Blood: Structure & Composition Flashcards
describe the structure and function of blood. (24 cards)
what is blood?
a special connective tissue
why is blood considered special tissue?
it is the only tissue that is mobile
why is blood called a tissue?
it is a group of cells that all perform a similar function.
why is blood called connective tissue?
its cells perform a function, but have a structural role as well.
what percentage of blood is plasma?
55%
what percentage of blood is cellular?
45%
what percentage of blood is the ‘buffy coat’?
<1%
what is the buffy coat?
WBCs and platelets
what is the other name for platlets?
thrombocytes
from what are platlets formed?
megakaryocyte
how are platelets different than normal cells?
they are only cellular fragments, with no nucleus or major organelles.
what is the average amount of platelets present in the blood?
450,000/dL
what is the function of platelets?
clot a cut, plugging it and preventing blood loss.
what are the two types of stem cells that produce the cells present in blood?
- myeloid progenitor
2. lymphoid progenitor
what are the types of cells that can form when a myeloid progenitor specialises?
- RBCs
- platelets
- macrophages
- basophils
- neutrophils
what are the types of cells that can form when a lymphoid progenitor specialises?
- B cells
2. T cells
where are haemopoetic stem cells present?
in the bone marrow.
what is plasma composed of?
water (90%)
proteins (7%)
salts & lipids (3%)
what are the three major proteins present in the blood?
- albumin
- clotting factors
- immunoglobulins
what is the role of albumin?
it 1) transports degradations of blood from the spleen to the liver; 2) maintains oncotic pressure
what is oncotic pressure?
a form of osmotic pressure, induced by proteins in the blood plasma, that displaces H2O
how does tissue fluid form?
when plasma leaks through the gaps between capillary cells into the spaces between body cells
how is the composition of tissue fluid?
almost identical to that of blood plasma.
why does plasma move out of the blood?
- due to the presence of a solute conc. gradient;
2. because of high hydrostatic pressure on the arterial side of a capillary bed.
