The systemic circulation Flashcards
What are vessels arranged in ?
Series - all blood flows round
Parallel- can split off
What do capillaries have?
greatest cross section area in vessels
Where is the majority of blood found at any given time?
Venous blood
What happens to velocity as Cross Sec. area increases?
DECREASES
Where is the velocity flow the fastest?
aorta and major arteries
Where is the velocity flow the slowest?
capillaries - so exchange can occur
What is Vasculature made of?
Aorta arteries arterioles capillaries venules veins vena cava
What are 3 distinct layers of blood vessel walls?
1) Tunica adventitia- connective tissue, OUTER
2) Tunica Media- smooth muscle and elastin in lumen
3) Tunica Intima- endothelium
What is the Arterial system?
1) Elastic arteries
2) muscular arteries
3) Arterioles
`What are elastic arteries ?
aorta and major arteries
- large diameter & low resistance so flows fast
Where is there a lot of elastin in elastic arteries?
tunica media
What are muscular arteries?
deliver blood to specific organs
What are muscular arteries like?
smaller with wide diameter and less Elastin
where is a lot of smooth muscle in muscular arteries?
tunica media
What does smooth muscle do?
control diameter
What are arterioles?
deliver blood to capillary beds
what is tunica media in arterioles?
smooth muscle so vasoconstriction/dilation
What do capillaries have?
small diameter - one blood cell at a time
What are 2 types of capillaries ?
continuous capillary
Fenestrated capillary
What are continuous capillary?
have tight intracellular gaps between endothelial cells
What are fenestrated capillaries?
fenestrations
wider intracellular gaps
allow filtration of small solutes/ permeable fluids
What are the Metarteriole Bypasses?
vessel that bypass true capillaries
What is Precapillary Sphincter?
ring of smooth muscle - regulates capillary flow
What is venous system?
Veins
venules
What are Venules?
when capillaries come together
What are walls of Large venules like?
thinly dispersed tunica media and adventitia
What are veins like?
thin walls
large lumen
have valves
why are veins called capacitance vessels?
accommodate large amount of blood
What do all vessels but capillary/ venule have ?
- endothelial cells
- elastin
- smooth muscle
- collagen
What happens blood closer to heart?
greater the pressure
Where is systemic blood pressure highest?
Aorta
Where is systemic blood pressure lowest?
Atrium
What do arterioles regulate?
blood pressure in systemic blood pressure
What is Systolic pressure?
highest arterial pressure
What is Diastolic pressure?
lowest arterial pressure
How to measure blood pressure?
Sphygomomanometer
when do Korotkoff sounds occur?
laminar flow in artery interrupted
What is Arteriole end of capillary bed pressure like?
lower than Venous end of capillary bed
What is Venous blood pressure like?
low and steady
What causes increase in Venous return ?
1) increase in blood volume
2) Skeletal muscle pump
3) Respiratory pump
4) Venoconstrictions
What is respiratory pump?
INSPIRE = compresses abdominal veins and thoracic veins expand
What is the Skeletal pump?
skeletal muscle contract it squeezes veins
