Blood and blood vessels Flashcards

1
Q

What are the 3 layers of the blood vessel wall?

A

Tunica intima, Tunica media and Tunica externa/adventitia

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2
Q

What are the 2 components of the Tunica intima?

A

Squamous Endothelium supported by a basal lamina and sub-endothelial connective tissue

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3
Q

What is the tunica media composed of?

A

Smooth muscle (some elastic fibres and external elastic lamina)

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4
Q

What is the Tunica externa/adventitia formed from?

A

Connective tissue

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5
Q

What is the name given to the blood cells that supply the tunica externa/adventitia?

A

Vasa vesorum

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6
Q

What layer separates the Tunica intima and the Tunica media?

A

The internal elastic membrane

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7
Q

What layer operates the Tunica media and the Tunica adventitia?

A

The external elastic membrane

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8
Q

What colours does Verhoeff’s/Mason trichome stain colour the walls of an elastic artery?

A

Elastic fibres - Black, Collagen - Green, Smooth muscle cells - Red

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9
Q

What adaptation occurs within the largest arteries (e.g. the aorta)?

A

A large amount of the smooth muscle within the tunica media is replaced my many sheets of elastic fibres to provide elastic recoil

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10
Q

Which layers of the blood vessel wall are supplied by the vasa vasorum?

A

The tunica adventitia and the furthest parts of the tunica media

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11
Q

What supplies the vasa vasorum with its blood?

A

The artery itself

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12
Q

What is the typical diameter of an arteriole?

A

30-200 micrometres

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13
Q

What are the 4 main structures between the small arteriole and the post-capillary venue?

A

metaarterioles, thoroughfare channels, capillaries and precapillary sphincters

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14
Q

What is the structure and function of the a pre-capillary sphincter?

A

They are composed of smooth muscle at the beginning of the capillary to help control blood flow through the network

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15
Q

What is the diameter of a capillary?

A

4-8 micrometres

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16
Q

What type of tissues contain no capillaries?

A

Epithelial cells resting on the basement membrane, the epidermis of the skin, hair and nails, the cornea of the eye and hyaline cartilage.

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17
Q

How are the epithelial cells resting on the basement membrane supplied?

A

They diffuse up from the lamina propria

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18
Q

What are the 3 types of capillary?

A

Continuous, Fenestrated and Discontinuous/Sinusoidal

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19
Q

Where are continuous capillaries found?

A

Muscle, nerve, lung and skin

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20
Q

What is the average size of the fenestrations within a fenestrated capillary?

A

50 nanometres

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21
Q

What type of endothelium is found in a continuous capillary?

A

Continuous epithelium

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22
Q

What are the characteristics of the epithelium of a fenestrated capillary?

A

They have no breaks, but small fenestrations

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23
Q

What are the characteristics of the epithelium of a sinusoidal capillary?

A

Breaks between epithelial cells

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24
Q

Where are fenestrated capillaries found?

A

Gut mucosa, endocrine glands and in the kidneys

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25
Q

Where are discontinuous/sinusoidal capillaries found?

A

In the liver, spleen and bone marrow

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26
Q

What is the diameter of a post-capillary venule?

A

10-30 micrometres

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27
Q

What is the structure and function of a post-capillary venule?

A

They are endothelial cell lined and contain a thin layer of connective tissue. They are important sites of exchange e.g. cells moving into the tissue during inflammation

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28
Q

At what point does a post-capillary venue become a venule?

A

When they begin to acquire intermittent smooth muscle cells in the tunica media

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29
Q

What are the characteristics of a vein?

A

They have a Tunica intima, a thin but continuous tunica media, typically consisting of a few layers of smooth muscle cells. There is an obvious Tunica adventitia

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30
Q

What are the characteristics of the Tunica adventitia of a large vein?

A

It incorporates bundles of longitudinally orientated smooth muscle

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31
Q

How do small veins prevent the back flow of blood?

A

They have valves which are inward extensions of the Tunica intima

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32
Q

What is the function of the lymph system?

A

They drain excess tissue fluid into the blood stream and transport lymph to lymph nodes for immunological surveillance

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33
Q

How does the lymph system produce flow?

A

Though there is no central pump, smooth muscle in the vessel walls, hydrostatic pressure in the tissue and compression of the vessels by voluntary muscle all produce flow

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34
Q

What percentage of the blood is made up of formed elements?

A

45%

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35
Q

What percentage of the blood is made up of plasma?

A

55%

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36
Q

What are the 3 main types of formed elements?

A

Red cells, white cells and platelets

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37
Q

What are the 2 main types of white cells?

A

Granulocytes and Agranulocytes

38
Q

What is the difference between a granulocyte and an agranulocyte?

A

Granulocytes contain many granules in their cytoplasm while agranulocytes contain none

39
Q

What are the 3 types of granulocytes?

A

Neutrophils, Eosinophils and Basophils

40
Q

What are the 2 types of agranulocytes?

A

Lymphocytes and monocytes

41
Q

What percentage of plasma is water?

A

90%

42
Q

What are the 3 most common types of proteins found in the plasma?

A

Albumin, immunoglobulins and clotting factors

43
Q

What is the average adult blood volume?

A

4.5-6 litres

44
Q

How is blood separated?

A

By centrifugation

45
Q

What is the hematocrit?

A

The proportion of blood that is red blood cells

46
Q

What is the average male hematocrit?

A

42 =42% of blood volume is red blood cells

47
Q

What is the average female hematocrit?

A

38

48
Q

What is the term given to the blood after the clotting factors are removed?

A

Serum

49
Q

How is serum usually obtained?

A

It is usually obtained by allowing the blood to clot, and then removing the clot, before spinning the blood

50
Q

What are the 3 layers of a centrifuged hematocrit tube?

A

Plasma, buffy coat and erythrocytes

51
Q

What is contained in the buffy coat of hematocrit tube?

A

leukocytes and platelets

52
Q

What is the medical name of a red blood cells?

A

Erythrocytes

53
Q

What are the characteristics of an erythrocyte?

A

They are biconcave discs, around 7 micrometers in diameter. mature erythrocytes are not true cells as they have no nucleus or organelles. Around 1/3 of the cells volume is taken up by haemoglobin

54
Q

What allows erythrocytes to deform and slip through spaces smaller than themselves?

A

They have a flexible cytoskeleton

55
Q

How long do erythrocytes last in circulation?

A

They last approximately 4 months

56
Q

Which organs remove aged cells?

A

The spleen and liver

57
Q

What percentage of white blood cells are neutrophils?

A

40-75%

58
Q

What percentage of white blood cells are Eosinophils?

A

5%

59
Q

What percentage of white blood cells are basophils?

A

0.5%

60
Q

What percentage of white blood cells are Lymphocytes?

A

20-50%

61
Q

What percentage of white blood cells are monocytes?

A

1-5%

62
Q

What are the characteristics of a neutrophil?

A

Their cytoplasm contains many granules that only show under neutral stains (hence ‘neutro’) They have a prominent multi-lobed nucleus.

63
Q

What is the function of a neutrophil?

A

They circulate in an inactive state, but if stimulated by bacteria or inflammation, they enter tissue where they act as highly mobile phagocytes

64
Q

What are the characteristics of a Eosinophil?

A

They have a bi-lobed nucleus. Their granules contain many hydrolytic enzymes. The prominent granules in the cytoplasm have an affinity for the stain Eosin.

65
Q

What is the function of an Eosinophil?

A

They are important in inducing and maintaining inflammation, especially in allergic reactions and asthma. They are also important in fighting parasitic infection.

66
Q

What is the life cycle of an eosinophil?

A

They are released from the marrow and circulate for 8-12 hours before moving into the tissue of the spleen, lymph nodes and GI tract.

67
Q

What are the characteristics of Basophils?

A

Their prominent granules in the cytoplasm have an affinity for basic dyes such as methylene blue. they have a bi-lobed nucleus. Their granules contain histamine, heparin and other inflammatory mediators

68
Q

What is the function of a Basophil?

A

They 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 to their antigen, the cell is stimulated to release its granules (degranulation). This leads to hay fever, allergic asthma and allergic dermatitis

69
Q

What are monocytes?

A

Monocytes are the precursors of tissue macrophages.

70
Q

What do monocytes and tissue macrophages form?

A

The mononuclear phagocyte system

71
Q

Where are macrophages most commonly found?

A

In loose connective tissue

72
Q

What are the characteristics of monocytes?

A

They have numerous small lysosomal granules in their cytoplasm. They are the largest circulating blood cells and have a non-lobulated nucleus, which appears kidney-bean shaped.

73
Q

What are examples of resident cells (none moving) of the mononuclear phagocytic system?

A

Kupffer cells in the liver, microglia in the brain and Langerhans cells in the skin

74
Q

What are the characteristics of a lymphocyte?

A

They have a round nucleus surrounded by a thin to moderate rim of cytoplasm

75
Q

What are the 2 general classes of lymphocytes

A

T and B

76
Q

What is the function of a B cell?

A

Give rise to antibody secreting plasma cells

77
Q

What are some of the functions of T cells?

A

Aiding other immune cells and killing defective cells.

78
Q

Where do T cells differentiate?

A

In the Thymus

79
Q

What are platelets?

A

Small cell fragments

80
Q

What is the average diameter of a platelet?

A

around 2 micrometres

81
Q

What are the characteristics of a platelet?

A

They have a well developed cytoskeleton. they have some organelles but no nucleus. They have conspicuous granules that include, among other things, some coagulation factors

82
Q

What does the cytoskeleton of a platelet participate in?

A

Extrusion of granules and clot retraction

83
Q

Where is the earliest site for erythrocyte formation?

A

Outside the embryo in the yolk sac, beginning at about 3 weeks gastration

84
Q

What are the later sites for erythrocyte formation during development?

A

The liver and spleen are colonised by hematopoetic stem cells. During the second trimester, the liver is the principle site of blood formation.

85
Q

Where is the main site of hematopoesis by birth?

A

The bone marrow of essentially all bones, however, as bones grow, there is excess capacity, some it shuts down in many bones

86
Q

Which bones are the site of hematopoesis after bone growth?

A

vertebrae, ribs, skull, pelvis and proximal femurs.

87
Q

What is the marrow of non-hematopoetic bones made of?

A

Adipose tissue, however, they can revert to blood formation

88
Q

What type of bone marrow cell is responsible for platelet production?

A

Megakaryocytes

89
Q

What is the diameter of a megakaryocyte?

A

30-100 micrometres

90
Q

What are the characteristics of a megakaryocyte?

A

Their nucleus undergoes multiple duplications of its nuclear material, but doesn’t undergo nuclear or cell division, so it has a very large nucleus.

91
Q

How are platelets formed?

A

They are formed from extensions of the outer margin of the megakaryocytes, which fragment from the cell