Blood Vessels

Question 1

Arteries

Answer 1

• thick tunica media
• need to expand to accept blood under great pressure
• need to recoil as blood flows during diastole to allow blood to flow towards capillaries during ventricle relaxation

Question 2

Arterioles

Answer 2

• tunica media composed of smooth muscle fibres and very few elastic fibers
• blood flow determined by arteriole diameter
• alter arterial BP via vasoconstriction and vasodilation

Question 3

Veins

Answer 3

• thinner walled overall, but thick tunica externa
• less elastic and smooth muscle tissue
• modified to ensure venous return = CO despite its low BP, and blood flow against gravity

Question 4

Venules

Answer 4

• tunica media contains only a few muscle cells and fibroblast
• porous endothelium allows for escape of many phagocytotic WBC

Question 5

Arterial System

Answer 5

-made of:
>elastic arteries
(thick walled, closest to heart, most elastic)
>muscular arteries
(next to elastic arteries, thickest tunica media, delivers blood to specific body organs)
>arterioles

Question 6

Capillaries

Answer 6

• walls one layer thick (super thin)
• decreased BP
• large surface area
• facilitate gas exchange

Question 7

Capillary beds

Answer 7

• made of: a vascular shunt (vessel connecting arteriole to venule) and true capillaries (with precapillary sphincters)
• microcirculation: blood from arteriole to venule

Question 8

True capillaries

Answer 8

• actual exchange happens
• branch off terminal arteriole
• empty directly into post capillary sphincter
• entrance guarded by precapillary sphincters

Question 9

Precapillary sphincters

Answer 9

-allows capillaires to be closed, forcing blood to flow through a vascular shunt

Question 10

Venous return

Answer 10

• large veins have Valves to help pump blood
• muscular pump: skeletal muscles surrounding veins contract and relax, pushing blood towards the heart
• respiratory pump: drop in thoracic pressure while breathing causes large veins near the heart to expand