Cardiovascular system: Blood vessels Flashcards

1
Q

What are the different types of arteries?

A

Elastic arteries, muscular arteries and arteriole

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2
Q

Where are elastic arteries found?

A

Just off the heart (where the pressure is highest FYI)

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3
Q

What is a unique property of elastic arteries compared to other types of arteries?

A

They are elastic and expand when the pressure increases

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4
Q

What makes the elastic arteries elastic?

A

They are made of sheets of elastin in the middle tunic (i.e. the middle layer)

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5
Q

When do the elastic arteries stretch?

A

During the contraction of the left ventricle

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6
Q

Why do the elastic arteries stretch when the heart beats?

A

The ventricle pumps blood faster than blood can flow therefore the arteries convert some energy into elastic energy

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7
Q

What is the benefit of the elastic arteries absorbing some of the energy from the heart beat?

A

During relaxation the elastic artery release the elastic energy and pumps more blood therefore smoothing out the pulses of pressure so there is a more continuous flow of blood

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8
Q

What is the function of muscular arteries?

A

distribution blood around the body at a high pressure and in the lungs at a medium pressure

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9
Q

What is the structure of muscular arteries?

A

Collagen layer of outer tunic (for binding to surrounding tissue), layers of smooth muscle in the middle tunic and a layer of endothelial cells on the inner tunic

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10
Q

How do the muscular arteries control blood pressure?

A

The smooth muscle can vasoconstrict or dilate to increase or decrease blood pressure

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11
Q

How is flow rate proportional to radius?

A

By the fourth power (i.e. flow ~ r^4)

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12
Q

When doing exercise, how will the muscular arteries respond?

A

They will vasodilate for the muscles to allow for increased blood flow and vasoconstrict for the digestive system as it isn’t necessary

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13
Q

What is the function of the arteriole?

A

It controls blood flow into the capillary beds

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14
Q

How doe she muscular wall of the arteriole compare relatively to the other arteries?

A

It is the thickest muscular wall of any artery

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15
Q

Why is the muscular wall of the arteriole much thicker relatively?

A

They have to protect the capillaries by reducing the pressure to the arteries the most therefore experience the greatest resistance.

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16
Q

Why do the arterioles have to protect the capillaries?

A

Because the capillaries are very thin walled (singled layer of endothelial cells) and are unable to control blood pressure

17
Q

What does the degrees of construct of the arterioles throughout the body determine?

A

total peripheral resistance which in turn affects the mean arterial blood pressure

18
Q

What is the structure of arteriole’s?

A

A layer of endothelial cells on the inside and layers of smooth muscle surround the lumen

19
Q

What is the function of capillaries?

A

Allow exchanges of gases, nutrients and wastes between blood and the surrounding tissue fluid

20
Q

What is the structure of capillaries?

A

A single cell thick layer of endothelial cells

21
Q

How do the capillaries affect the shape of the red blood cells? What does this result in?

A

Capillaries are so narrow that they cause the red blood cells to bend

This causes significant damage to the cells which requires them to be replaced frequently

22
Q

How do nutrients get in and out of the capillaries?

A

The capillaries are leaky so plasma can flow out of the capillaries containing nutrients (but goes back into capillaries due to osmotic gradient FYI) and the blood cells stay in the capillaries and diffuse their gases

23
Q

What is the process of nutrients from the capillaries to the cells?

A

Capillary –> interstice fluid –> cells

24
Q

What is the function of a venule?

A

Drains capillary beds and during infection and inflammation venules are where the white blood cells leave the blood to attack bacteria

25
Q

How are venules able to perform their functions?

A
  • draining capillary beds: lower pressure than surrounding tissue therefore excess interstitial fluid re-absorbed
  • white blood cell response: slow blood movement therefore they can move in and out of vessel as needed
26
Q

What are venules similar to? How are they different?

A

They are very similar to capillaries (thin walled of endothelium) except they have connective tissue (capillaries have none)

27
Q

What is the function of veins? What is the exception to this rule?

A

To drain blood back to the heart and as a reservoir of blood

Portal veins, drain blood between different capillary beds (i.e. intestine to liver)

28
Q

What is the structure of a vein?

A

Thin elastic walls with bicuspid valves (mailing in the legs) lining all along the wall of the vein

29
Q

What is the function of the bicuspid valves? Why are they needed

A

Prevent the back flow of deoxygenated blood down the vein, in particular in the legs

The blood pressure in the veins is very low and without the valves, un-oxygenated blood would drain back into capillary beds

30
Q

How do veins act as a reservoir of blood?

A

During rest they can expand and store more blood as the body doesn’t need as much oxygenated blood (FYI at rest 64% of blood in veins, 13% in arteries)

31
Q

How do the veins react when you start to exercise?

A

The veins constrict which put more blood into the arterial system

32
Q

How do the muscles help blood move up the veins? Where is this particular important and why?

A

As the muscle contract it squeezes the veins. Due to the bicuspid valves it prevents the blood from flowing backward so the blood can only go forward therefore acts as a venous pump

Importnat in the legs as the blood has to go a long way back up the body

33
Q

What is the function of the coronary arteries?

A

Supply the heart with oxygen

34
Q

Why does the heart need coronary arteries even though it has so much blood around it?

A

The heart muscle is thick, in particular the left ventricle, and diffusion along is not fast enough to supply all the heart with oxygen therefore vessels to supply the cells directly are needed. Also the right side of the heart is pumping deoxygenated blood and it needs a supply of oxygenated blood

35
Q

What is atheroma?

A

Degeneration of the arteries by scar tissue and fatty deposits

36
Q

If a coronary artery is narrowed to about 20% of its normal cross-section by atheroma, what does this cause? During exercise what can this cause?

A

Causes significant obstruction to blood flow

The myocardium (heart tissue) supplied by the artery runs low on oxygen causing iscehmia resulting in chest pain (angina). Severe iscehmia result in death of a local area of myocardium (infarction)

37
Q

What is a response by the body to atheroma?

A

Different arterial vessels join up and widen slowly so that ischaemic myocardium can be supplied by a different artery (that is further away FYI)