CVS 1 Structure And Function Of CVS

Question 0

Where does the lymphatic system drain between?

Answer 0

Capillaries draining into large veins by heart

Question 1

How much blood will a large man contain?

Answer 1

6l

Question 2

Where does blood flow fastest? (In relation to cross sectional area)

Answer 2

Where cross sectional area is least

Question 3

Which elastic arteries branch from the aortic arch?

Answer 3

Brachiocephalic, left common carotid, left subclavian

Question 4

What are the major elastic arteries of the body?

Answer 4

R and L pulmonary arteries, aorta, braciocephalic, left common carotid, subclavian, L and R common iliac arteries

Question 5

What happens in elastic arteries in systole and diastole?

Answer 5

Systole- LV contraction causes BP in aorta to rise to about 120mmHg and walls of elastic aorta and other elastic arteries stretch Diastole- aortic semilunar valve closes, aorta walls recoil maintaining pressure on blood and moving it towards the smaller vessels, aortic pressure drops to 70-80mmHg

Question 6

What are the three major types of artery?

Answer 6

Elastic conducting- widest Muscular distributing- intermediate diameter, most of named arteries Arterioles-narrowest

Question 7

What are the three layers of arteries and veins?

Answer 7

Tunica intima Tunica media Tunica adventitia

Question 8

What is diffusion affected by?

Answer 8

Area available for exchange- capillary density Diffusion resistance- nature of barrier, nature of molecules diffusing, PATH length Conc grad- most importantly affected by flow of blood rather than conc of substances in blood

Question 9

Outline amount of blood flow needed to body and brain. Which other organs must blood be delivered to at all times?

Answer 9

Body- 5 to 25L/min Brain- 0.75L/min Heart muscle and kidneys Note: date of blood flow=perfusion rate

Question 10

Describe the major functional components of the circulation

Answer 10

Pump-heart Distribution vessels- arteries Flow control- arterioles and precapillary sphincters are the resistance vessels ensuring appropriate distribution do cardiac output Capacitance-ability to cope with changes in CO-store of blood in veins to cope with imbalances in blood returning and blood needing to be pumped out

Question 11

Where is the majority of blood stored?

Answer 11

Veins

Question 12

What do muscular arteries branch into?

Answer 12

Arterioles

Question 13

What do arterioles regulate?

Answer 13

Amount of blood reaching an organ or tissue and blood pressure

Question 14

What controls diameter of arteries and arterioles?

Answer 14

Autonomic nervous system

Question 15

What do arterioles branch into?

Answer 15

Metarterioles

Question 16

How many cells thick are capillary walls?

Answer 16

1

Question 17

What is an end artery?

Answer 17

A terminal artery supplying all or most of blood to a body part without significant collateral circulation

Question 18

Give three examples of end arteries

Answer 18

Renal, splenic, coronary

Question 19

Where are the precapillary sphincters?

Answer 19

Between metarterioles and capillaries

Question 20

Where do lymphatic capillaries return extra cellular fluid?

Answer 20

Junctions of internal jugular and subclavian veins

Question 21

What are the typical diameters of capillaries?

Answer 21

7-10um

Question 22

What are continuous capillaries?

Answer 22

Most common type with cells joined by tight or occluding junctions. Located in nervous, muscle and connective tissues, exocrine glands and lungs. Endothelial layer is continuous

Question 23

What are fenestrated capillaries?

Answer 23

Capillaries where there are little interruptions across thin parts of endothelium bridged by a thin diaphragm(except in renal glomerulus). Found in parts of gut, endocrine glands and renal glomerulus

Question 24

What are sinusoidal/discontinuous capillaries?

Answer 24

Larger capillaries (30-40um) with slower blood flow with gaps in walls allowing whole cells to move between blood and tissue. Found in liver, spleen and bone marrow

Question 25

What are pericytes?

Answer 25

Cells that from a branching network on outer surface of endothelium of capillaries. These are capable of dividing into muscle cells, or fibroblasts during angiogenesis, tumour growth and wound healing

Question 26

What type of valves do veins contain?

Answer 26

Paired semilunar. These ensure blood flows one way

Question 27

Which veins don’t have valves?

Answer 27

Those narrower than 1mm and those in thoracic and abdominal cavities

Question 28

How do muscles contribute to blood flow in veins

Answer 28

Muscle pump action in leg helps pump blood upwards against gravity

Question 29

Describe elastic artery structure

Answer 29

Endothelium Thick tunica media with 40-70 fenestrated elastic membranes with smooth muscle and collagen between lamellar.thin external elastic lamina may be present. Tunica adventitia- layer of fibroelastic connective tissue containing vasa vasorum lymph vessels and nerve fibres

Question 30

Describe the structure of muscular arteries

Answer 30

Tunica intima- endothelium Tunica media 40 layers of smooth muscle cells connected by gap junctions for coordinated contraction, prominent external elastic lamina Tunica adventitia- thin fibroelastic connective tissue layer containing vasa vasorum lymph vessels and nerve fibres

Question 31

What nerve fibres act on muscular arteries?

Answer 31

Sympathetic nerve fibres stimulate vasoconstriction. Release noradrenaline which diffuses through fenestration in external elastic lamina to tunica media to depolarise superficial smooth muscle cells

Question 32

Describe arteriole structure

Answer 32

Arteries with 1-3 layers of smooth muscle in tunica media. Thin elastic lamina only present in large arterioles External elastic lamina absent Scant tunica adventitia

Question 33

In which blood vessels is velocity at its lowest

Answer 33

Capillaries

Question 34

What are venae comitantes?

Answer 34

Deep paired veins that accompany some small arteries on either side, the three vessels being wrapped in one sheath. The pulsing of the artery promoted venous return in the veins. Examples are brachial, ulnar and tibial venae comitantes

Question 35

What are vasa vasorum?

Answer 35

Small blood vessels that supply or drain the walls of larger arteries and veins. Embedded in tunica adventitia

Question 36

What is the outermost layer of the pericardium? What is it attached to?

Answer 36

Fibrous pericardium. Bound to central tendon of diaphragm where extrapericardial fat can often be seen radiographically. Also attached to sternum by sternopericardial ligaments. Also stuck to mediastinal pleura except where the two separated by phrenic nerves

Question 37

What makes up the inner pericardium

Answer 37

Serous pericardium- parietal layer lining the fibrous pericardium, visceral layer lining heart. Thin fluid layer between known as pericardial cavity.

Question 38

What is the transverse sinus?

Answer 38

Passage posterior to aorta and pulmonary trunk and anterior to left atrium and superior vena cava that you can pass a finger through upon opening pericardial sac anteriorly

Question 39

What is the oblique sinus?

Answer 39

The reflection of the pericardium at the venous end giving an inverted u along pulmonary veins and inferior vena cava

Question 40

Describe the orientation of the heart

Answer 40

Lies obliquely (diagonally) between 3rd and 5th ribs, mainly on left side of midline of thorax but with roughly a third of it slightly to the right. Base: posterior surface-left atrium Apex: most inferior and lateral part of left ventricle lying beneath 5th intercostal space at midclavicular line.

Question 41

Describe borders of heart

Answer 41

Right: right atrium between superior and inferior venae cava Left:left auricle and left ventricle Inferior:mainly right ventricle with a little left ventricle Superior: right and left atria and their auricles