histology of blood vessels

Question 1

what are the 3 layers of blood vessels

Answer 1

tunica externa (adventitia) tunica media tunica intima

Question 2

in the heart, whch layers correspond with the 3 tunicas

Answer 2

tunica intima = endocardium tunica media (muscle layer) = myocardium tunica externa = epicardium

Question 3

stucture of tunica intima

Answer 3

epithelium, BM, connective tissue

Question 4

structure of tunica media

Answer 4

muscle + elastic tissue

Question 5

difference between epicardium and tunica externa

Answer 5

epicardium - fibrous connective tissue, BM, epithelium tunica externa - fibrous connective tissue

Question 6

diameter of artery vs vein

Answer 6

arteries are smaller diameter than accompanying vein veins tend to be floppy and expanded due to thinner TM than artieries which are more contracted

Question 7

wall of artery vs vein

Answer 7

arteries have thicker wall than accompanying vein arteries have thin TM and thin adventitia (less need to stabilise) vein has thicker adventitia

Question 8

tunica media and adventitia thickness artery vs vein

Answer 8

artery - thick media, thin adventitia vein - thin media, thick adventitia

Question 9

individual diameters of blood vessels comparison

Answer 9

artery > arterioles > capillaries

Question 10

total cross sectional area of blood vessels comparison

Answer 10

arteries < arterioles < capillaries capillary bed has huge SA

Question 11

what are the 3 types of arteries

Answer 11

elastic muscular arterioles

Question 12

elastic arteries

Answer 12

large conducting expand and contract to move blood around e.g. aorta, common carotid, pulmonary

Question 13

muscular arteries

Answer 13

distributing arteries less elasticity, more of a channel for the blood e.g. coronary arteries, radial, femoral

Question 14

arterioles

Answer 14

terminal branches which supply blood to the capillary bed

Question 15

what is the function of elastic arteries

Answer 15

pressure reservoir

Question 16

state of elastic arteries during systole and diastole

Answer 16

stretched during systole during diastole heart relaxes, pressure falls, artery recoils, maintaining pressure on the blood

Question 17

what is the recoil and stretchability in elastic arteries due to

Answer 17

presence of extensive amounts of elastic fibres in tunica media in the form of layers (laminae)

Question 18

what are the elastic fibres in elastic arteries secreted by

Answer 18

smooth muscle cells

Question 19

what type of vessel is this and why?

Answer 19

elastic artery

very thin tunica intima

lots of layers of elastic fibres in the TM which are obscuring the muscle

elastic fibres occur in layers

Question 20

what is the function of muscular arteries

Answer 20

controls distribution of blood to regions

Question 21

describe the structure of muscular arteries

Answer 21

thick tunica media has smooth muscle cells

no elastic laminae between muscle cells in TM

elastic fibres are concentrated in 2 well defined sheets called the internal elastic lamina (IEL)just under the epithelium and the external/outer elastic lamina (OEL) between TM and TA

Question 22

what type of blood vessel is this and why

Answer 22

muscular artery

smooth muscle cells

presence of OEL and IEL

Question 23

streucture of arterioles

Answer 23

no IEL

only 1-2 layers of smooth muscle in TM

no T adventitia

round oval nuclei visible in smooth muscle

Question 24

function of arterioles

Answer 24

smaller muscular arteries gradually change histologically to become arterioles

control blood flow to capillary beds (local)

control systemic blood pressure

Question 25

nerve innervation of arterioles

Answer 25

rich sympathetic nerve innervation controls diameter

Question 26

what type of blood vessel is this and why

Answer 26

arteriole

Question 27

function of capillaries

Answer 27

main exchange site for nutrients and gases low BP

Question 28

structure of capillaries

Answer 28

very thin walled T intima only - endothelium on BM no TM or TA pericytes sum of diameters of all capillaries in body \> diameter of aorta lumen only big enough for one RBC

Question 29

what are pericytes

Answer 29

incomplete layer of cells surrounding BM have contractile properties which help control the flow of blood in the capillaries

Question 30

what type of blood vessel is this and why

Answer 30

capillaries

Question 31

what are the 3 types of capillaries

Answer 31

continuous fenestrated discontinuous

Question 32

continuous capillaries

Answer 32

no gaps in endothelium complete basal lamina found in muscles

Question 33

fenestrated capillaries

Answer 33

fenestrated endothelial lining complete basal lamina allows more substance through gaps are sometimes abridged by protein membranes but not always found in endocrine glands

Question 34

discontinuous capillaries

Answer 34

fenestrated endothelial lining incomplete basal lamina lots of stuff allowed through found in liver sinusoids

Question 35

function of continuous capillaries

Answer 35

can control what is exchanged material must pass through cell or between cells junctions can control transport - selective transport mechanisms

Question 36

fenestrated capillary function

Answer 36

fenestrations with or without protein diaphragms which filter molecules by MW and/or charge e.g. endocrine glands, kidney renal corpuscle

Question 37

function of discontinuous capillaries

Answer 37

gaps between endothelial cells and BM allow free passage of fluid and cells e.g. liver, spleen, bone marrow

Question 38

sinusoids

Answer 38

large diameter discontinuous capillaries found where large amount of exchage takes place TI contains phagocytic cells e.g. liver, some endocrine glands

Question 39

capillary beds and arteriovenous shunts

Answer 39

bypasse capillary beds e.g. in skin for thermoregulation

Question 40

veins blood vessel progression

Answer 40

capillary bed small venule small-medium vein large

Question 41

structure of veins

Answer 41

thin TI IEL and OEL thin or absent TM very thin or absent TA - collagenous tissue valves to prevent backflow (endothelial projections into lumen)

Question 42

what can the failure of valves in veins lead to

Answer 42

varicose veins

Question 43

what type of blood vessel is this

Answer 43

vein

Question 44

superficial vs deep veins

Answer 44

difference most obvious in lower limb veins tend to have a corresponding artery that they mirror superficial - thick walled compared to deep, no surrounding support deep - thin walled, surrounding support from deep fascia and muscle, close to the bone

Question 45

lympathic system

Answer 45

tends to lie next to big vessels (esp veins), nodes found alongside major veins and origins of major arteries drains tissue fluid lost from blood capillaries drains into the systemic venous system valves direct flow

Question 46

why is the lymphatic system clinically important

Answer 46

tumour cell metastases cancerous cells can easily spread to other places in the body lymphogenic spread - spread through the lymphatic system

Question 47

describe the structure of lymph capillaries

Answer 47

blind ended capillaries lined by very thin endothelium no fenestrations absent/rudimentary basal lamina lumen maintained at -ve hydrostatic pressure anchoring filaments - fine collagenous filaments link endothelial cell to surrounding tissue keeping lumen open NO RBC in lumen

Question 48

blood vessels as organs

Answer 48

nerve supply - sympathetic (skin), sympathetic + parasympathetic (heart) blood supply - vasa vasorum (vessels of the vessels) lymphatics in T adventitia