Histology of Blood Vessels and Blood Film (Function of Blood Cells)

Question 1

What are the 3 layers of a blood vessel?

Answer 1

• tunica intima (internal)
• tunica media (middle)
• tunica adventitia (external)

Question 2

What are the features of the tunica intima?

Answer 2

• single squamous epithelium (endothelial cells)
• cells supported by basal lamina and thin layer CT

Question 3

What are the features of the tunica media?

Answer 3

• made up of predominantly smooth muscle
• variable thickness

Question 4

Describe the tunica adventitia

Answer 4

outer layer made of supporting CT

Question 5

What separates the tunica intima and tunica media?

Answer 5

internal elastic membrane

Question 6

What separates the tunica media and the tunica adventitia?

Answer 6

external elastic membrane

Question 7

Why are the largest arteries (e.g. aorta) called elastic arteries?

Answer 7

sheets of elastic fibres replacing a significant amount of smooth muscle in the tunica media

Question 8

What is the vaso vasorum?

Answer 8

vascular supply to large elastic arteries

Question 9

Why do some elastic arteries have their own vascular supply?

Answer 9

only the inner part of the wall can obtain nutrients from lumen

Question 10

What is an arteriole?

Answer 10

smallest division of muscular arteries

Question 11

What happens to the layers of the arteries as they get smaller?

Answer 11

• tunica media loses smooth muscle
• tunica adventitia starts to disappear

Question 12

What is the function of arterioles?

Answer 12

control blood flow in tissues

Question 13

What are the 2 types of arteriole?

Answer 13

• terminal arteriole
• meta arteriole

Question 14

What are the features of terminal arterioles?

Answer 14

• no internal lamina
• covered by continuous coat of smooth muscle cells

Question 15

What are the features of meta arterioles?

Answer 15

• smooth muscle cells replaced by pericytes
• terminate into capillaries

Question 16

What is a pericyte?

Answer 16

non-contractile cells in arterioles

Question 17

What are the components of capillaries?

Answer 17

• endothelial cells
• basal lamina

Question 18

Where are capillaries absent?

Answer 18

• epithelial cells resting on basement membrane
• epidermis of skin, hair, nails
• cornea
• hyaline cartilage

Question 19

What are the 3 types of capillaries?

Answer 19

• continuous
• fenestrated
• sinusoidal

Question 20

Describe the features of continuous capillaries?

Answer 20

• uninterrupted endothelium
• continuous basal lamina
• fine filaments

Question 21

What are the features of fenestrated capillaries?

Answer 21

• capillaries with small openings/pores
• pores allow large molecules and proteins to move between organs and blood

Question 22

What are the features of sinusoidal capillaries?

Answer 22

• capillaries with large gaps
• allow blood cells and proteins to pass between blood and tissue

Question 23

Where would you find continuous capillaries?

Answer 23

• muscles
• nerves
• lungs
• skin

Question 24

Where would you find fenestrated capillaries?

Answer 24

• gut mucosa
• endocrine glands
• kidney

Question 25

Where would you find sinusoidal capillaries?

Answer 25

- liver - spleen - bone marrow

Question 26

Where do capillary networks drain into?

Answer 26

post-capillary venules

Question 27

Describe the structure of post-capillary venules.

Answer 27

- lined by endothelial cells - thin layer of CT

Question 28

When do capillaries become referred to as venules?

Answer 28

once the vessel begins to acquire intermittent smooth muscle in the tunica media

Question 29

Describe the structure of veins

Answer 29

- thin continuous tunica media - obvious tunica adventitia - valves (inward extensions of TI)

Question 30

What is the function of valves in veins?

Answer 30

prevent the back flow of blood

Question 31

What are the features of large veins?

Answer 31

- thick tunica adventitia - TA incorporates bundles of longitudinally orientated smooth muscle

Question 32

What is the distribution of blood in the body (most to least)

Answer 32

- peripheral veins - heart and lungs - peripheral arteries - capillaries

Question 33

What is the average adult blood volume?

Answer 33

4.5 - 6 litres

Question 34

What are the components of blood?

Answer 34

- 45% formed elements - 55% plasma

Question 35

What are the formed elements of blood?

Answer 35

- red blood cells - white blood cells - platelets

Question 36

What is the composition of plasma?

Answer 36

- 90% water - proteins (albumin, clotting factors, clotting factors) - nutrients - salts

Question 37

What are the features of erythrocytes?

Answer 37

- biconcave discs - 7 micrometres - no nucleus/organelles - network of flexible cytoskeletal elements that allow them to deform

Question 38

How long do erythrocytes last in circulation?

Answer 38

~ 4 months

Question 39

What removes old RBCs from circulation?

Answer 39

- liver - spleen

Question 40

Define haematocrit

Answer 40

the proportion of a persons blood that is red blood cells

Question 41

What is the average haematocrit of an adult male?

Answer 41

~42

Question 42

What is the average haematocrit of an adult female?

Answer 42

~38

Question 43

What are the 2 types of white blood cells (leukocytes)?

Answer 43

- granulocytes - agranulocytes

Question 44

What leukocytes are granulocytes?

Answer 44

- neutrophils - eosinophils - basophils

Question 45

What leukocytes are agranulocytes?

Answer 45

- lymphocytes - monocytes

Question 46

Describe the features of neutrophils.

Answer 46

- most common - prominent, multi-lobed nucleus - circulate in an inactive state - become highly mobile phagocytes when stimulated - abundant and short-lived

Question 47

Describe the features of eosinophils

Answer 47

- bilobed nucleus - granules stain pink - granules contain hydrolytic enzymes - induce and maintain inflammation - respond to allergic reactions and asthma

Question 48

Describe the features of basophils

Answer 48

- rarest of granulocytes - granules stain dark (obscure nucleus) - bilobed nucleus - granules contain histamine, heparin - effector cells in allergic reactions

Question 49

How do basophils cause allergic responses?

Answer 49

- high affinity IgE receptors in cell membrane - when bound to allergen cell is stimulated to release granules

Question 50

What are features of monocytes?

Answer 50

- precursors to macrophages - widely distributed - found in loose CT - largest circulating cells - kidney bean shaped nucleus - small granules

Question 51

What are the feature of macrophages

Answer 51

- part of mononuclear phagocytic system - some wander - some remain in tissues

Question 52

What are the features of lymphocytes?

Answer 52

- large round nucleus - no visible nucleus - T and B cells - T cells differentiate in thymus - B cells give rise to antibody secreting plasma cells

Question 53

What are the features of platelets?

Answer 53

- small cell fragments - 2 micrometres - large numbers in blood - key role in haemostasis (blood clotting) - well developed cytoskeleton

Question 54

What is haemopoiesis?

Answer 54

the formation of new blood cells

Question 55

Where is the main site of blood formation at birth?

Answer 55

bone marrow

Question 56

What happens as bones enlarge?

Answer 56

haemapoiesis stops in many bones

Question 57

What bones produce blood by the time the skeleton reaches maturity?

Answer 57

- vertebrae - ribs - skull - pelvis - proximal femurs