The blood vessels Flashcards
What are elastic fibres?
Elastic fibres are made from elastin which allows them to stretch and recoil. This allows the walls of the vessels to be flexible
What is smooth muscle?
The smooth muscle allows the vessel to contract or relax in order to change the size of the lumen
What is collagen?
The collagen provides structural support to maintain the shape and volume of the vessel
Draw and label a diagram of an artery
What is the function of the arteries?
They carry the oxygenated blood away from the heart and around the body.
During pregnancy what is the function of the umbilical artery?
The umbilical artery carries deoxygenated blood from the fetus to the placenta.
Is the blood in the arteries under low or high pressure?
High
What are arteries constructed out of?
Lumen Endothelium Elastic fibres Smooth muscle Collagen
What is the purpose of the elastic fibres inside of the arteries?
The elastic fibres can stretch which enables the arteries to withstand the high pressure and large volume of the blood coming from the heart. In between the contractions of the heart the elastic fibres recoil and return to there original length.
What is the purpose of the elastic fibres inside of the arteries?
The elastic fibres can stretch which enables the arteries to withstand the high pressure and large volume of the blood coming from the heart. In between the contractions of the heart the elastic fibres recoil and return to there original length. This feature helps to even out the surges of blood pumped from the heart so that there is a continuous flow.
What is in the arteries which limits how far the elastic fibres can stretch?
The callogen limits how far the elastic fibres can stretch
Why does the endothelium (lining if the artery) need to be smooth?
So that the blood can flow easily through it
Write out the different arteries in order of size
Aorta Medium sized artery Arteriole
Describe the structure of the arteriole compared to an artery
Arterioles have more smooth muscle and less elastin in there walls compared to arteries.
Why do the arterioles have a small elastic layer?
As they are further away from the heart they have little pulse surge and so do not need to expand and recoil as much as an artery.
How can arterioles control the volume of blood that is accessed by individual organs?
The smooth muscle of an arteriole contracts which constricts the vessel and prevents blood flow.
When the blood flow in the arteriole is constricted what is the result and what is the name given?
The blood is prevented from flowing into a capillary bed. This is called vasoconstriction
What happens with the smooth muscle in the wall of an arteriole relaxes and what is the name given?
Blood is able to flow into the capillary bed. This is called vasodilation
What is a capillary bed?
a network of capillaries
How large is the diameter of an aorta?
2.5cm
How large is the diameter of a medium-sized artery?
0.4cm
How large is the diameter of an arteriole?
30um
Draw a chart to show the size of the elastic, smooth muscle and callogen layers in the aorta, medium-sized artery and arteriole
Check page 179
Draw and label a diagram of a capillary
check pg 179
How large is the diameter of a red blood cell?
7-8um
What is the order of the blood vessels?
Arteries, arterioles, capillaries, venules, veins
In what parts of the body does the blood entering the capillaries have less oxygen then when they leave?
The lungs and the placenta
What are the 3 ways in which the capillaries are adapted for there role in exchange?
- They have a large surface area
- As the capillaries are larger than the erythrocytes the rate of blood flow slows which allows more time for exchange
- The walls are very thin (1 endothelial cell thick)
What is the function of the veins?
The veins carry the deoxygenated blood back to the heart
What do the pulmonary veins do?
They carry oxygenated blood from the lungs to the heart.
What does the umbilical vein do during pregnancy?
It carries oxygenated blood from the placenta to the fetus
At the end of its journey, how does the blood from the upper part of the body return to the heart?
Via superior vena cava
How much of your blood volume is in your veins at any given time?
60%
Why do veins not have a pulse?
Because they are too far away from the heart, and so surges of the heart pumping are lost through the capillaries.
What is the blood pressure like in the veins compared to the arteries?
The blood pressure in the veins is very low compared to the arteries
Draw a diagram that explains the function of valves inside medium sized veins
Check pg 181
What is the name given to a group of venules?
A vein
Draw a chart which represents the size of the elastin, smooth muscle and callogen inside the large veins, medium-sized veins and venules
Check page 181
How large is the diameter of a large vein?
>1cm (greater than 1cm)
How large is the diameter of a medium-sized vein?
less than 1cm
How large is the diameter of a venule?
0.1mm
What is the problem with returning the blood from the veins to the heart?
The blood in the veins are under low pressure and need to defy gravity
What are the three ways in which the body helps move the blood from the veins to the heart?
- Most of the veins are lined with valves which prohibit the blood from flowing the other way.
- Many of the big veins are located along the active muscles of the body. As the muscle contracts it squeezes the veins which moves the blood towards the heart.
- The breathing movement of the chest acts as a pump. The pressure change and the squeezing action helps moves the blood along the chest and abdomen back to the heart.
Crash course blood vessels video
Crash course blood vessels part 2
What is the function of the pulmonary artery?
The pulmonary artery caries deoxygenated blood from the heart to the lungs.
