8.2 Blood vessels

Question 1

3 types of components used in blood vessels

Answer 1

elastic fibres: made of elastin & can stretch+ recoil, giving flexibility

smooth muscle: contracts/ relaxes to change size of lumen

collagen: provides structural support to maintain shape and volume of vessel

Question 2

What is the artery

Answer 2

these carry blood away from the heart to tissues of body
–> carry oxygenated blood except in pulmonary artery
(takes deoxygenated blood from right ventricle to lungs)

Question 3

structure of arteries

Answer 3

narrow lumen (innermost) / very thick muscle walls
—> outermost layer of collagen, muddle layer of smooth muscle and elastic fibres, inner layer of endothelium

Question 4

Why do arteries have elastic fibres?endothelium?

Answer 4

to withstand force of blood pumped out of heart and stretch to take larger volume of blood
–> flexibility allows fibres to recoil and return to normal length, helping to pump blood continuously

endothelium is smooth so blood flows easily over it

Question 5

What is an arteriole

Answer 5

arteries branch into narrower blood vessels called arterioles which transport blood into capillaries
–> link arteries and capillaries

Question 6

Structure of an arteriole

Answer 6

more smooth muscle and less elastin in walls
–> they have little pulse surge but constrict and dilate to control flow of blood into individual organs

Question 7

Vasoconstriction and vasodilation

Answer 7

vasoconstriction: when smooth muscle of arteriole contracts, constricting the vessel and prevents blood flowing into a capillary bed

vasodilation: when smooth muscle relaxes, blood flows through into capillary bed

Question 8

What is a capillary?

Answer 8

microscopic blood vessels that link arterioles with venules
–> form an extensive network through all tissues of body

Question 9

Where is the main area for substance transfer rom capillaries to cells?

Answer 9

gaps between endothelial cells that make up capillary walls
–> substances pass into fluid surrounding cells

Question 10

adaptions of capillaries

Answer 10

1. large surface area for diffusion of substances
2. total cross-sectional area of capillaries is greater than arteriole = rate of blood slows
   –> more time for diffusion between capillaries and cells
3. walls are a single endothelial cell thick = very short diffusion distance

Question 11

What are veins?

Answer 11

carry deoxygenated blood away from body cells & towards heart
–> except pulmonary vein: carries oxygenated blood from lungs to left atrium

Question 12

Flow of blood from arteries to veins

Answer 12

Artery –> arterioles –> capillary bed –> venules –> veins

Question 13

What are the two main veins that carry deoxygenated blood back to heart

Answer 13

inferior vena cava (blood from lower parts of body)

superior vena cava (blood from upper body and head

Question 14

Structure of veins

Answer 14

wide lumen, thin walls
–> thin outer, middle and inner layers compared to arteries
–>walls contain lots of collagen and little elastic fibre & smooth endothelium

Question 15

adaptions of body to overcome blood moving under low pressure

Answer 15

veins have one-way valves at intervals: flapping/infoldings of inner lining of vein (prevents blood backflow)

bigger veins tend to run between big and active muscles
–> when muscles contract, they squeeze veins, forcing blood towards heart

breathing movements of chest act as a pump
–> pressure changes and squeezing actions move blood in veins of chest and abdomen towards the heart