Blood Vessels Flashcards
How many layers are in the basic structure of a blood vessel
3
Tunica intima
Tunica media
Tunica adventitia
What are the layers of a blood vessel from inner to outermost
Tunica intima
Tunica media
Tunica adventitia
What is the tunica intima made up of
A single layer of squamous epithelial cells termed endothelial cells supported by a basal lamina and a thin layer of connective tissue
What is the tunica media made up of
Made up of predominantly smooth muscle. Thickness can vary tremendously
What is the tunica adventitia made up of
Made up of supporting connective tissue
What separates the tunica intima from the tunica media
A layer of elastic tissue called the internal elastic membrane
What separates the tunica media and the tunica adventitia
A layer of elastic tissue called the external elastic membrane
What are vasa vasorum
Small blood vessels that supply the walls of larger arteries.
What are capillaries composed of
Capillaries are composed of endothelial cells and a basal lamina
How many types of capillaries are there
3
Continuous
Fenestrated
Discontinuous or sinusoidal
Examples of continuous capillaries
Muscle, nerve, lung, skin
Examples of fenestrated capillaries
Gut mucosa, endocrine glands, kidney
Examples of discontinuous or sinusoidal capillaries
Liver, spleen, bone marrow
Why do small veins have valves
To prevent back flow of blood
How is lymph moved to lymph nodes
No central pump, but smooth muscle in walls, hydrostatic pressure in the tissue and compression of the vessels by voluntary muscle, combined with valves in the vessels, produces flow.
Where is blood found in the body
Peripheral veins, heart and lungs, peripheral arteries and capillaries.
How is serum obtained when separating blood
Serum is usually obtained by allowing the blood to clot, and then removing the clot before spinning the blood.
Describe Erythrocytes
Often termed Red Blood Cells.
Biconcave discs.
They are not true cells as they have no nucleus or organelles.
1/3 of their volume taken up by the iron containing protein haemoglobin.
They contain a network of flexible cytoskeletal elements that allow them to deform and slip through smaller spaces than themselves.
What are Leukocytes, and how many types are there.
White blood cells
5 - (neutrophils, eosinophils, basophils, lymphocytes, monocytes)
What is the most common type of leukocyte
Neutrophils are granulocytes and are the most common type of leukocyte.
What happens when Neutrophils are stimulated.
Neutrophils circulate in an inactive state, but if stimulated, for example by the presence of bacteria or inflammation, they enter the tissue where they are highly motile phagocytes.
Why is a significant portion of bone marrow devoted to the production of Neutrophils.
Neutrophils are both abundant and short lived which means a significant potion of the bone marrow is devoted to their production.
Describe Eosinophils
Eosinophils typically have a bilobed nucleus.
Why are granules important in Eosinophils.
Their granules contain a variety of hydrolytic enzymes and they are important in inducing and maintaining inflammation, particularly in allergic reactions and asthma. They are also important in fighting parasitic infection.
Describe basophils
Basophils are the rarest of the granulocytes.
What gives basophils an intense stain colour.
The prominent granules in the cytoplasm of basophils have an affinity for basic dyes such as methylene blue and with this dye, stain intensely blue-purple.
Describe Basophils
Basophils have a bilobed nucleus but this is often obscured by the granules. these granules contain histamine, heparin and other inflammatory mediators.
Describe how basophils respond in allergic reactions.
Basophils act as effector cells in allergic reactions. High affinity IgE receptors in their cell membrane are directed against a particular allergen and when they bind their antigen the cell is stimulated to release its granules. this leads to hay fever, allergic asthma, allergic dermatitis.
What are Monocytes?
Monocytes serve as the precursors of tissue macrophages and together they form what is termed the mononuclear phagocyte system.
Where are macrophages found?
Macrophages are widely distributed in the body, but are particularly found in loose connective tissue.
Do Monocytes have lysosomal granules in their cytoplasm.
monocytes have numerous small lysosomal granules in their cytoplasm. They are the largest cells circulating in the blood and have a non-lobulated nucleus which often appears kidney bean-shaped.
Describe Lymphocytes
Lymphocytes have a round nucleus surrounded by a thin to moderate rim of cytoplasm that does not have visible granules.
How many classes of lymphocytes are there
There are 2 general classes of lymphocytes, B cells and T cells, however these cannot be distinguished in routine stained sections.
What are the differences and similarities between B cells and T cells.
Both types of lymphocytes arise in the bone marrow, but T cells differentiate in the thymus. both cell types participate in the specific immune response. B cells given rise to antibody secreting plasma cells while T cells form a complex set of cells that perform many defence functions.
What are platelets
In addition to red blood cells and leukocytes, the formed elements of blood include platelets. these are small cell fragments found in large numbers in the blood. Platelets play a key role in hemostasis (prevention of blood loss).
Explain platelets and their skeletons.
Platelets have a well developed cytoskeleton, which participates in extrusion of granules and in clot retraction. platelets have some organelles, but no nucleus. they have conspicuous granules that include, among other things, some coagulation factors.
What is hemopoiesis
Earliest site for erythrocyte formation is outside the embryo in the yolk sac beginning at about 3 weeks gestation. Later the liver and to some extent the spleen is colonised by hemopoietic stem cells. thus during the second trimester the liver is the principal site of blood formation.
What is the main site of blood formation by birth
By birth the bone marrow is the main site of blood formation and essentially all bones participate. as bones enlarge there is excess capacity and so hemopoiesis is shut down in many bones.
By the time the skeleton reaches maturity which bones retain hemopoiesis.
By the time the skeleton reaches maturity, only the vertebrae, ribs, skull, pelvis and proximal femurs retain hemopoiesis.
What are Megakaryocytes
Megakaryocytes are large cells of bone marrow that produces platelets. It undergoes multiple duplications of its nuclear material but doesn’t undergo nuclear or cell division-so the nucleus is very large. the platelets are formed as extensions at the outer margin of the cell which fragment from the cell.
