Blood Vessels and Blood Flashcards
what are the three layers of a blood vessel from inside to outside?
tunica intima
tunica media
tunica adventitia
what is the tunica intima made of?
single layer of endothelial cells
supported by a basal lamina and a later of connective tissue
what is the tunica media made of?
smooth muscle
what is the tunica adventitia made of?
supporting connective tissue
what separates the tunica intimacy from the tunica media?
the internal elastic membrane
what separates the tunica media from the tunica adventitia?
the external elastic membrane
what is the vascular supply to the walls of large arteries called?
vasa vasorum
why do large arteries need the vasa vasorum?
only the inner part of the wall can obtain nutrients from the lumen
what happens to the wall of the vessel as an artery becomes an arteriole?
loose smooth muscle - tunica media only one or two layers thick
lose the adventitiaa
what are capillaries composed of?
endothelial cells on a basal lamina
what are the three types of capillaries?
continuous
fenestrated
discontinuous/sinusoidal
where are continuous capillaries found?
muscle
nerves
lungs
skin
describe the structure of a fenestrated capillary
small pores in the wall
where are fenestrated capillaries found?
gut mucosa
endocrine glands
kidneys
describe the structure of discontinuous capillaries
have large gaps in their walls
where are discontinuous capillaries found?
liver
spleen
bone marrow
where is the vast majority of blood found?
the peripheral veins
what are the two main parts of blood?
formed elements
plasma
what are the three formed elements of blood?
red cells
white cells
platelets
what are the two groups of white cells?
granulocytes
granulocytes
name the three granulocytes
neutrophils
eosinophils
basophils
name the two agranulocytes
lymphocytes
monocytes
what three things make up plasma?
water
proteins
nutrients and salts
how can blood be separated into its components?
centrifuge
blood at the bottom, then white cells then plasma
what is serum?
blood when clotting factors have been removed
what are erythrocytes?
red blood cells
describe the structure of erythrocytes
biconcave discs
no nucleus or organelles
what do erythrocytes contain?
haemoglobin
how long do erythrocytes last in circulation?
four months
how are aged erythrocytes removed from circulation?
by the spleen and liver
what are leukocytes?
white blood cells
what is the most common leukocyte?
neutrophils
describe the structure of neutrophils
cytoplasm contain granules
prominent, multi lobed nucleus
what colour do eosinophils stain and why?
red
granules have an affinity for acidic eosin
describe the structure of eosinophils
bilobed nucleus
granules
what are eosinophils important for?
inflammation
parasitic infections
what is the rarest granulocyte?
basophils
what colour do basophils stain and why?
blue/purple
granules have an affinity for basic methylene blue
describe the structure of basophils
bilobed nucleus, often obscured by granules
what do basophils granules contain?
histamine
heparin
other inflammatory markers
what do basophils do?
act as effector cells in allergic reactions
describe the structure of lymphocytes
round nucleus surrounded by a thin rim of cytoplasm containing no granules
what are the two classes of lymphocytes?
T and B
where do lymphocytes arise?
bone marrow
what do monocytes serve as precursors for?
tissue macrophages
where are monocytes particularly located?
loose connective tissue
what is the largest blood cell?
monocytes
describe the structure of monocytes
lysosomal granules
kidney bean shaped nucleus
what are monocytes called in the liver?
Kupffer cells
what are monocytes called in the brain?
microglia
what are monocytes called in the skin?
langerhan’s cells
what blood cells play a key role in haemostats?
platelets
what is the earliest site for erythrocyte formation and when does this occur?
yolk sac
around three weeks gestation
where is the primary site of blood formation in the second trimester?
the liver
what is the main site of blood formation at birth?
bone marrow
what bones retain haemopoiesis by the time the skeleton matures?
vertebrae ribs skull pelvis proximal femurs