Functional histopathology of the CV system

Question 1

Circulatory system functions

Answer 1

transport of oxygen and nutrients to the tissues

transport of carbon dioxide and other metabolic waste products from the tissues

involved in temp regulation

distribution of molecules (hormones) and cells (immune system)

Question 2

What are the 2 functional components of the circulatory system?

Answer 2

blood vascular system

lymph vascular system

Question 3

Arteries function

Answer 3

efferent vessels to carry blood and nutrients and oxygen to tissues

Question 4

Capillaries function

Answer 4

complex network of thin tubules, interchange between blood and tissues takes place

Question 5

Veins function

Answer 5

convey the blood back towards the heart to be pumped again

Question 6

Describe the tunica intima

Answer 6

inner lining comprising a single layer of flattened epithelial cells (endothelium)
supported by basement membrane and collagenous tissue

Question 7

Describe the tunica media

Answer 7

intermediate muscular layer
smooth muscle and elastic fibre layer regulated by sympathetic nervous system
controls vasoconstriction/vasodilation of vessels

Question 8

Describe the tunica adventitia/externa

Answer 8

an outer supporting tissue
collagen fibres protect and support vessels
larger vessels contain vaso vasorum

Question 9

What is the vaso vasorum?

Answer 9

Small blood vessels that supply the walls of larger arteries and veins

Question 10

Define endothelium

Answer 10

single layer of squamous epithelium, lining the internal surfaces of all components of the blood and lymphatic systems

Question 11

Describe the functions of the endothelium

Answer 11

selective permeable anthrombotic barrier

determines when and where white blood cells leave circulation for the interstitial space of tissue

secretes paracrine factors for vessel dilation, constriction and growth of adjacent cells

Question 12

Name some large elastic arteries

Answer 12

aorta and its large branches (innominate, subclavian, common carotid and iliac)
pulmonary arteries

Question 13

What happens in elastic arteries during systole and diastole?

Answer 13

high content of elastic fibre so media expands during systole and stores some of the energy of each heartbeat
elastic recoil of the vascular wall during diastole propels blood through the more distal vessels

Question 14

Describe elastic (conducting) arteries

Answer 14

large lumen allow low resistance conduction of blood
contain elastin in all 3 tunics
withstand and smooth out large blood pressure fluctuations
allow blood to flow fairly continuously throughout the body

Question 15

Describe muscular arteries

Answer 15

tunica intima has endothelial lining and some connective tissue
thicker tunica media than vein and narrower lumen and thicker elastic laminae

more smooth muscle and less elastin in tunica media than elastic arteries

Question 16

Describe the structure of arterioles

Answer 16

tunica intima is continuous endothelium and thin subendothelial layer

generally tunica media has 2 layers of smooth muscle cells
(smallest arterioles = 1 layer)
tunica adventitia = thin sheath of connective tissue

Question 17

Describe the structure of capillaries

Answer 17

just big enough for single file erythrocytes
single layer of endothelial cells surrounded by basement membrane
some have tissue specific functions

Question 18

Universal functions of capillaries (not tissue-specific)

Answer 18

oxygen and nutrient delivery to tissues
carbon dioxide and nitrogenous waste removal

Question 19

Where are continuous capillaries present?

Answer 19

muscle
lungs
central nervous system

Question 20

Where are fenestrated capillaries present?

Answer 20

endocrine glands
sites of metabolic and fluid absorption (eg. gallbladder, kidney and intestinal tract)

Question 21

Where are discontinuous (sinusoidal) capillaries present?

Answer 21

liver
spleen
bone marrow

Question 22

Describe continuous capillaries

Answer 22

have endothelial cells that provide an uninterrupted lining

Question 23

What are the 3 types of capillaries?

Answer 23

continuous
fenestrated
discontinuous/sinusoidal

Question 24

Describe fenestrated capillaries?

Answer 24

endothelium riddled with pores
greater permeability to solutes and fluids than other capillaries

Question 25

Describe sinusoidal capillaries

Answer 25

highly modified, leaky, fenestrated capillaries with large lumens
discontinuous layer of endothelial cells with wide spaces between
basal lamina is discontinuous
allow large molecules (proteins and blood cells) to pass between blood and surrounding tissues

Question 26

Veins function and how are they classified?

Answer 26

collect blood from all tissues and organs and return it to the heart

classified by size:
- venules
- medium-sized veins
- large veins

Question 27

How does blood return to the heart in veins?

Answer 27

contraction of tunica media
external compressions from surrounding muscles

Question 28

Where do valves project from and what is their function?

Answer 28

project from the tunica intima
prevent backflow of blood

Question 29

What are the special features of veins?

Answer 29

veins contain valves (prevent backflow of blood, most abundant in legs where blood has to travel against gravity)

muscular contraction (aids return of blood to heart in conjunction with valves)

Question 30

Compare arteries and veins (lumen, thickest layer, tunica intima)

Answer 30

artery = narrow lumen, thicker tunica media, intima separated from media by internal elastic lamina

vein = larger lumen, tunica externa is thickest, tunica intima is folded to form valves)

Question 31

What are the 3 tunics of the heart wall?

Answer 31

internal = endocardium
middle = myocardium
external = pericardium

Question 32

What is the function of the fibrous central region of the heart (fibrous skeleton)?

Answer 32

serves as a base of the valves
site of origin and insertion of cardiac muscle cells
electrical insulator between atria and ventricles

Question 33

List the electrical pathway of the heart

Answer 33

sinoatrial node
atrioventricular node
bundle of his
left and right bundle branches
purkinje fibres

Question 34

Where is the sinoatrial node located and what is it’s function?

Answer 34

pacemaker of the heart
located near the junction of the right atrial appendage and the superior vena cava

Question 35

Where is the AV node located and what is it’s function?

Answer 35

located in the right atrium along the atrial septum
delays transmission of signals from atria to ventricles - ensures that atrial contraction precedes ventricular contraction

Question 36

Where is the bundle of his located?

Answer 36

courses from right atrium to the summit of the ventricular septum