Histology: Blood and Blood Vessels

Question 1

what are the 3 layers of blood vessels (inner to outer)

Answer 1

• tunica intima
• tunica media
• tunica adventitia

Question 2

describe the tunica intima

Answer 2

single squamous endothelium supported by a basal lamina

Question 3

describe the tunica media

Answer 3

smooth muscle of varying thickness

Question 4

describe the tunica adventitia

Answer 4

supporting connective tissue

Question 5

what separates the 3 layers of blood vessels

Answer 5

internal and external elastic membranes

Question 6

what are elastic arteries and why is this the case

Answer 6

• larger arteries where the tunica medias smooth muscle is replaced by elastic tissue
• allows for greater elastic recoil

Question 7

what is Verhoeff’s/Masson Trichome stain

Answer 7

• elastic fibres, black
• collagen, green
• smooth muscle, red

Question 8

what are vaso vasorum

Answer 8

blood supply to vaso vasorum

Question 9

describe the layers in an arteriole

Answer 9

• smaller tunica media and therefore less smooth muscle
• almost no adventitia
• control blood flow to tissues

Question 10

what are capilaries composed of and what are the 3 types

Answer 10

• endothelial cells and basal lamina
• continuous
• fenestrated
• discontinuous

Question 11

describe a continuous capillary and where its typically found

Answer 11

• continuous

- muscle, nerve, lung, skin

Question 12

describe a fenestrated capillary and where its typically found

Answer 12

• has small pores

- gut mucosa, endocrine glands, kidney

Question 13

describe a discontinuous capillary and where its typically found

Answer 13

• has large pores

- liver, spleen, bone marrow

Question 14

what is the function of pre-capillary sphincters and what are the composed of

Answer 14

• control blood flow through the network

- smooth muscle

Question 15

describe the path blood takes through the microvasculature

Answer 15

small arteriole -> meta-arteriole -> pre-capillary sphincter -> capillary -> thouroughfare channle -> post-capillary venules

Question 16

describe the compositin of venules

Answer 16

endothelial cells and thin connective tissue layer

Question 17

venules are important sites of what

Answer 17

exchange, i.e. inflammation

Question 18

when are blood vessels classified as venules

Answer 18

when their tunica media has intermittent smooth muscle

Question 19

when are blood vessels classed as veins

Answer 19

when they have a tunica intima, continuous tunica media and tunica adventitia

Question 20

what is the tunica adventitia like on the largest veins

Answer 20

thick with longitudinal smooth muscle

Question 21

what are valves and what is their purpose

Answer 21

inward extensions of the endothelium, prevent backflow of blood

Question 22

give an overview of blood flow form elastic arteries to large veins

Answer 22

elastic arteries -> arterioles -> small arteriole -> metarteriole -> pre-capillary sphincter -> capillary -> post capillary venule -> venules -> small veins -> big veins

Question 23

describe the vessels of the lymphatic system and its function

Answer 23

system of thin-walled vessels that transport lymph to lymph nodes for immune surveillance and drains excess lymph from tissues into blood stream

Question 24

how does the lymphatic system produce flow

Answer 24

• skeletal muscle pump
• smooth muscle in vessel walls
• hydrostatic pressure in tissue
• valves

Question 25

what are the formed component of blood

Answer 25

- plateltes - WBCs - RBCs

Question 26

what are the 2 main categories of WBCs

Answer 26

- granulocytes | - agranulocytes

Question 27

what type of cells are granulocytes

Answer 27

- mast cells - eosinophils - neutrophiols - basophils

Question 28

what type of cells are agranulocytes

Answer 28

- monocytes | - lymphocytes

Question 29

monocytes

Answer 29

- macrophages | - dendritic cells

Question 30

what type of cells are lymphocytes

Answer 30

- T cell - B cell - NK cell

Question 31

what is used to separate blood and how does its separate

Answer 31

- centrifuge | - RBCs on bottom -> WBCs -> plasma (densest - less dense)

Question 32

how is serum obtained

Answer 32

blood allowed to clot, clot remove and blood is then spun on centrifuge

Question 33

describe RBCs

Answer 33

bi concave, no nucleus, contain Hb and can deform to slip through small spaces

Question 34

how can RBCs slip through small spaces

Answer 34

contain a netwokr of flexible cytoskeleton elements

Question 35

how long do RBCs circulate and what removes them

Answer 35

- 4 months | - liver and spleen

Question 36

where is the majority of blood

Answer 36

peripheral veins

Question 37

describe neutrophils

Answer 37

- stains poorly - promient, multi-lobed nucleus - abundant and short lived

Question 38

what produces neutrophils

Answer 38

bone marrow

Question 39

describe the activation of neutrophils

Answer 39

circulate inactive and are stimulated by phagocyte/inflammation/etc, the enter the tissue and become phagocytotic

Question 40

describe eosinophils

Answer 40

- stain red (with eosin) - circulate and then move into tissue - bigger than neutrophils and contain a bilobed nucleus - granules contain hydrolytic enzymes

Question 41

function of eosinophils

Answer 41

- induce and maintain inflammation in allergic reactions and asthma - fight parasitic infections

Question 42

describe basophils

Answer 42

- stain blue/purple with basic dyes - bilobed nucleus often obscured by granules - granules contain inflammatory mediators

Question 43

how do basophiles function

Answer 43

- effector in allergic reactions - have high affinity for IgE and and react to a specific allergen - degranulates when antigen binds - lead to hayfever, asthma, allergic reactions, etc

Question 44

describe monocytes

Answer 44

- macrophage precursor - small lysosomal granules - biggest - kidney bean shaped nucleus

Question 45

where are macrophages found

Answer 45

mainly connective tissue but some are 'wanderers'

Question 46

where are (macrophages) - Kuppfer cells - Microglia - Langerhans cells found

Answer 46

- liver - brain - skin

Question 47

describe lymphocytes

Answer 47

- round nucleus surrounded by a thin cytoplasm - no granules - arise from bone marrow

Question 48

describe T cells and their function

Answer 48

- differentiate in thymus | - form complex set of cells that perform defense functions

Question 49

describe B cells function

Answer 49

- give rise to antobidy secreting plasma cells

Question 50

describe platelets

Answer 50

- small cell fragments - found in large numbers - no nucleus but some organelles - granules - cytoskeleton

Question 51

function of cytoskeleton and granules in platelets

Answer 51

- extrusion of granules and clotting factors | - granules include coagulation factors

Question 52

where is the earliest site of erythrocyte formation and where does it occur a little later

Answer 52

- outside the embryo in the yold sac at 3 weeks | - liver and spleen

Question 53

where does haemopeosis occur during - 2nd trimester - by birth

Answer 53

- liver | - bone marrow

Question 54

why does some bone marrow stop producing erythrocytes and which one maintain it

Answer 54

- as bones grow excess haemopoeisis happens so theyre not needed - pelvis, proximal femurs, ribs, skull, vertebrae

Question 55

what happens to the bone marrow that stops producing erythrocytes

Answer 55

- become adipose tissue | - convert to RBC formation in emergency