Blood and Blood Vessels

Question 1

Blood Components

Answer 1

formed elements (45%) - red cells, white cells, platelets; Plasma (55%) - water (-90%), proteins (mostly albumin, immunoglobulins, clotting factors), nutrients and salts

Question 2

Separating blood

Answer 2

with a centrifuge. Red blood cells are densest and found at the bottom of the tube, white blood cells are next in the buffy coat; plasma which is the liquid portion of blood is found on top.

Question 3

Serum

Answer 3

remaining liquid after clotting factors have been removed

Question 4

Erythrocytes (red blood cells)

Answer 4

7µm in diameter. Mature RBCs have no nucleus or organelles. Flexible cytoskeleton, can deform and slip through space smaller than themselves. Last 4 months.

Question 5

Leukocytes

Answer 5

white blood cells

Portions: neutrophils - 40-75%; lymphocytes- 20-50%; eosinophils - 5%; Monocytes - 1-5%; basophils - 0.5%

Question 6

Neutrophils

Answer 6

most common white blood cell.
Cytoplasm contains granules (which stain poorly with acidic or basic dyes). Prominent multi-lobed nucleus. Circulate in inactive state, when stimulated they enter tissue where they are highly motile phagocytes. Abundant and short lived.

Question 7

Eosinophils

Answer 7

Prominent granules in cytoplasm stain red. Are released from bone marrow and circulate for 8-12 hours, then move into tissue where they live. Typically have a bilobed nucleus. Granules contain hydrolytic enzymes important in inducing and maintaining inflammation, especially in allergic reactions and asthma. Important in fighting parasitic infection.

Question 8

Basophil

Answer 8

rarest of granulocytes. Prominent granules in cytoplasm stain intense blue-purple. Have a bilobed nucleus, but is often obscured by the granules (which contain histamine, heparin and other inflammatory mediators). Act as effector cells in allergic reactions.

Question 9

Monocytes

Answer 9

precursors of tissue macrophages and form the mononuclear phagocyte system. Have numerous small lysosomal granules in their cytoplasm. Largest cells circulating in the blood and have non-lobulated nucleus which often appears kidney bean shaped.

Question 10

Lymphocytes

Answer 10

round nucleus surrounded by a thin to moderate rim of cytoplasm with no visible granules. Two classes of lymphocyte: B cells and T cells, which cannot be distinguished in routine staining. Both types arise in bone marrow, but T cells differentiate in the thymus. Both participate in specific immune response.

Question 11

B cells

Answer 11

give rise to antibody secreting plasma cells

Question 12

T cells

Answer 12

from a complex set of cells that perform many defence functions (aiding other immune cells, killing defective cells etc)

Question 13

Platelets

Answer 13

small cell fragments about 2µm in diameter found in large numbers in the blood. Key role in hemostasis (prevention of blood loss). Have a well developed cytoskeleton, participating in extrusion of granules and clot retraction. No nucleus but some organelles. Have conspicuous granules including some coagulation factors.

Question 14

Blood Vessel Structure

Answer 14

3 layers: Inner layer - Tunica Intima; Middle layer - Tunica Media; Outer Layer - Tunica Adventitia

Question 15

Tunica Intima

Answer 15

Single layer of squamous epithelial cells, known as endothelial cells supported by a basal lamina and thin layer of connective tissue

Question 16

Tunica Media

Answer 16

predominantly smooth muscle. Thickness varies

Question 17

Tunica Adventitia

Answer 17

made up of supporting connective tissue

Question 18

Tunica Intima is separated from the Tunica Media

Answer 18

by the internal elastic membrane; a layer of elastic tissue

Question 19

Tunica Media is separated from Tunica Adventitia

Answer 19

by the external elastic membrane; a layer of elastic tissue

Question 20

Elastic Arteries

Answer 20

largest arteries (eg. aorta). Have many sheets of elastic fibres in their Tunica Media to provide elastic recoil

Question 21

Large Arteries have

Answer 21

own vascular supply; Vasa Vasorum, as only the inner part of the wall can obtain nutrients from the lumen. (eg. aorta)

Question 22

Arteriole

Answer 22

have only 1 or 2 layers of smooth muscle and almost no t. adventitia, as arteries get smaller they lose smooth muscle from t. media. Important in controlling blood flow in a tissue.

Question 23

Capillaries

Answer 23

composed of endothelial cells and a basal lamina, often smaller than RBC. 3 types: continuous - muscle, nerve, lung, skin; Fenestrated: small pores (50nm), gut mucosa, endocrine glands, kidney; Discontinuous/Sinusoidal: large gaps, liver, spleen, bone marrow.

Question 24

Microvasculature

Answer 24

small arteriole connected to a postcapillary venule, through a network made up of metarterioles, thoroughfare channels, and capillaries.

Question 25

Post-Capillary Venules

Answer 25

where capillary networks drain into. Endothelial cell-lined and contain a thin layer of connective tissue. Important sites for exchange (eg. cells moving into the tissue in inflammation)

Question 26

Venules

Answer 26

as post-capillary venules acquire intermittent smooth muscle cells in a tunica media layer, they’re referred to as venules

Question 27

Veins

Answer 27

have a tunica intima, thin but continuous tunica media (typically consisting of a few layers of smooth muscle cells) and an obvious tunica adventitia.

Question 28

Large Veins have

Answer 28

thick tunica adventitia which incorporates bundles of longitudinally orientated smooth muscle (eg. vena cava)

Question 29

Small Veins

Answer 29

have veins (inward extensions of the tunica intima) to prevent backflow of blood

Question 30

Lymph Vascular System

Answer 30

system of relatively thin walled vessels that drain excess tissue fluid (lymph) into the blood stream. Transports lymph to lymph nodes for immunological surveillance.

Question 31

Structure of lymph vascular system

Answer 31

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.

Question 32

Principle Site of Blood Formation

Answer 32

liver (during second trimester), bone marrow by birth and essentially all bones participate. As bones enlarge there is excess capacity and so hemopoiesis is shut down in many bones. When skeleton reaches maturity, only the vertebrae, ribs, skull, pelvis and proximal femurs retain hemopoiesis.