histology of blood vessels and blood film Flashcards
how can blood be separated
by spinning in a centrifuge
what are the 3 main components of blood
- erythrocytes (45%)
- buffy coat = leukocytes and platelets (<1%)
- plasma (55%)
what is plasma (2)
- plasma has clotting factors
- but if these are removed then you have serum
what are erythrocytes
red blood cells
describe th order of blood vessels that blood flows through from the heart out the aorta
- arteries
- elastic arteries
- muscular arteries
- arterioles
- terminal arterioles.(stops)
- meta arterioles (from arterioles)
- capillaries
- venules
- post capillary venules
- veins
what are elastic arteries and why are they called this
the very largest arteries e.g. the aorta
- called elastic arteries because they have many sheets of elastic fibres in their tunica media to provide elastic recoil
how do elastic arteries obtain nutrition and why
- due to the thickness of the tunica media only the inner part of the wall can obtain nutrients from the lumen
- this is why they have their own vascular supply called the vasa vasorum which is giving nutrition to the outer parts through diffusion
describe what changes to go from an artery to an arteriole
they arteries become smaller and lose smooth muscle from the tunica media until tunica media has only 1 or 2 layers of smooth muscle in their tunica media and almost no adventitia
describe terminal arterioles
- no internal lamina (between intimate and media?)
- covered by a continuous coat of smooth muscle cells
describe meta arterioles
- smooth muscle are replaced by dis-continuous non-contractile cells called pericytes
- terminates in to capillaries
describe capillaries
they are essentially made up of endothelial cells and a basal lamina (membrane)
name and describe the 3 types of capillaries
- continuous capillaries have no space between endothelial cells and has a continuous basal membrane, used in muscle, nerve, lung and skin cells
- fenestrated capillaries have small gaps between endothelial cells which cause pores but not clear openings, basal membrane is continuous. found in gut mucosa, endocrine glands and kidney cells
- discontinuous/sinusoidal capillaries have clear large gaps between endothelial cells and there are breaks in the basal membrane. found in the liver, spleen and bone marrow
what is the difference between post capillary venules and venues
- pcv are endothelial lined and contain a thin layer of connective tissue, they are important sites for exchange
- when pcv acquire intermittent smooth muscle cells in their in their tunica media they are referred to as venues
which is the most prominent layer of a vein and in what vein is this the largest in
they have a tunica intima, a thin but continuous tunica media consisting of a few layers of smooth muscle cells but they have an obvious tunica adventitia
- the largest veins e.g. vena cava have a thick tunica adventitia
what do small veins contain and why
valves
- to prevent the back flow of blood
describe erythrocytes (3)
- biconcave discs about 7µm in diameter
- mature RBC’s have no nucleus or organelles but a third of their volume is taken up by the iron containing protein, haemoglobin
- contain a network of flexible cytoskeletal elements that allow them to deform and slip through spaces smaller than themselves e.g. capillaries
what is haemolisis
the bursting of red blood cells
- they only survive in isotonic solution
why do erythrocytes appear red in colour
they are lined by plasma membrane which contains haemoglobin, causing them to appear red in colour
what on red blood cells contributes to the different blood groups
surface proteins
what is hematocrit and what is the average for an adult
the proportion of blood that is RBC’s e.g. a hematocrits of 40 means 40% of the blood is RBC’s
- adult men = 42
- adult women = 38
name the 3 types of granulocytes
- neutrophils (40-75% WBC)
- eosinophils (5%)
- basophils (0.5%)
describe neutrophils (4)
- contain a single, multi-lobed nucleus
- most common type of leukocyte
- are inactive until activated by bacteria or inflammation where they become phagocytes
- a significant portion of the bone marrow is devoted to their production
- their granules stain poorly with acidic or basic dyes (neutral/neutro)
describe eosinophils (5)
- have a bi-lobed nucleus
- contain acidic granules that stain red
- most granules are lysosomes
- granules contain a variety of hydrolytic enzymes and are important in inducing and maintaining inflammation, especially in allergic reactions and asthma
- also very important in parasitic infections
describe basophils (3)
- have a bilobed nucleus that is often obscured by the granules
- stain blue-purple
- act as effector cells in allergic reactions
name the 2 types of agranulocytes
- monocytes
- lymphocytes
describe monocytes (3)
- have a large, kidney-bean shaped nucleus that os not lobulated
- have small lysosomal granules in their cytoplasm
- are the precursor of tissue microphages which then together form the mononuclear phagocyte system
describe lymphocytes
- they have a small spherical nucleus with a basophilic (blue) cytoplasm
- contain B cells and T cells that both come from bone marrow but they cannot be distinguished by normal staining
- B cells give rise to antibody secreting plasma cells
- T cells differentiate in the thymus and form a complex set of cells that perform many defence functions
what are platelets
cell fragments that have a key role in haemostasis (the prevention of blood loss)
- they have some organelles but no nucleus
