CVS 3 Flashcards

1
Q

Describe plasma.

A

Plasma is the liquid component of blood, in which the red blood cells, white blood cells, and platelets are suspended.
It constitutes more than half of the blood’s volume and consists mostly of water containing dissolved salts (electrolytes) and proteins.

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2
Q

Describe red blood cells by giving its amount, protein, and function.

A

Red blood cells (also called erythrocytes) make up about 40% of the blood’s volume.
Red blood cells contain haemoglobin, is a protein that gives blood its red color and enables it to carry oxygen from the lungs and deliver it to the tissues of the body.

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3
Q

Describe white blood cells by giving its amount and function.

A

White blood cells (also called leukocytes) are fewer in number than red blood cells, with a ratio of about 1 white blood cell to every 660 red blood cells.
White blood cells are responsible primarily for defending the body against infection.

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4
Q

Describe platelets by giving its amount and function.

A

Platelets (also called thrombocytes) are cell-like particles smaller than red or white blood cells. Platelets are fewer in number than red blood cells, with a ratio of about 1 platelet to every 20 red blood cells.
Platelets help in the clotting process by gathering at a bleeding site and clumping together to form a plug that helps seal the blood vessel.

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5
Q

What is the haematocrit ratio and how is it measured?

A

Haematocrit Ratio is defined as the ratio of red blood cell (rbc) volume to the total blood volume, i.e. % rbc volume.

Measuring the ratio of the volume of red blood cells to the total volume of blood is typically performed by centrifugation.

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6
Q

Haematocrit varies from tissue to tissue and also with body condition, and is important because this determines the…

A

effective viscosity of the blood.
Blood represents ~ 7% of the total body mass, e.g. a 70 kg male has about 5 litres of blood.

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7
Q

Since the heat pumps about 80 ml of blood per contraction, it takes approximately _________ for an average blood cell to make one full cycle of the body.

A

1 minute

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8
Q

There are four stages to blood circulation, list them in detail.

A

1- In the diastole phase, the heart relaxes between beats. Blood moves into the heart. Both atriums are filled rapidly.

2- When the atriums contract, the systole (pumping) phase begins, blood pushes to ventricles via mitral and tricuspid valves.

3- The contraction of the ventricles forces the blood through semilunar valves into the pulmonary artery which leads to lungs, and through aorta to the rest of the body.

4- When the heart relaxes, the semilunar valves close, blood fills the atrium, beginning the cycle again.

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9
Q

Pumps can be classified to two categories:

A

Vacuum pumps, designed to reduces the pressure.
Forced pumps, designed to increases pressure such as circulating pumps like heart

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10
Q

The 2-synchronous pumps work on a basis similar to…

A

Boyle’s Law, which states that for a gas at constant temperature,
Pressure x Volume = Constant
(i.e. PV = constant).

Boyles law: Pressure is inversely proportional to volume.

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11
Q

In the heart chambers, as the chambers expand volume _____ and consequently the pressure ______.

A

increases, decreases (drawing blood into the chamber).

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12
Q

As the heart contracts, the volume ______, and the pressure ______.

A

decreases, increases (forcing blood out of the chamber)

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13
Q

The study of fluid in motion is called…

A

fluid dynamics

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14
Q

What is the streamline (or laminar flow)?

A

is a flow, that each particle of the fluid follow a smooth path called streamline , and these paths do not cross each other.
ex: flows in a smooth walled, straight section of clean blood vessel.

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15
Q

Streamline (or laminar) flow results in a…

A

minimum loss of energy in the flow, and is ‘silent’,
i.e. cannot be heard with a stethoscope placed over an artery.

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16
Q

What is turbulent flow?

A

The flow is not smooth and is not regular and characterised by erratic, small whirlpool- like circles called eddy current.

17
Q

Eddies absorb…

A

great deals of energy.

18
Q

What does the continuity principle state?

A

States that for an incompressible fluid, the rate of flow of fluid into one end of the channel must be equal to the rate of flow of fluid leaving the other end.

19
Q

It can be shown simply that the volume flow rate is given by:

A

𝑄=𝐴𝑣 [𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑖𝑛 𝑚^3/𝑠]
Where A is the cross-sectional area of the vessel and v is the velocity of the fluid.

20
Q

Since no fluid runs out of sides, therefore the flow rates (Q) through A1 and A2 must be…

A

equal.

21
Q

If the cross-sectional area is _____, then the flow velocity is _____, and vice versa.

A

reduced, increased

22
Q

The cross sectional area of the capillary network is much greater than the aorta, why?

A

We would expect the blood to flow much faster in the capillaries than in the aorta, since the cross-sectional area of 1 capillary is very much less than the cross-sectional area of the aorta. This is NOT the case, since the aorta feeds into millions of capillaries (via the arterioles).

23
Q

Consequently, blood flow speed in the aorta is ~ ______, whereas in the capillaries this reduces to around ______.

A

30 cm/s, 1 mm/s.

24
Q

The total cross-sectional area of the vessels increases with…

A

distance from the heart.

25
Q

The total cross-sectional area of the vessels increases with distance from the heart.
Consequently, the…

A

velocity of flow decreases, and then increases after passing the capillaries.

26
Q

If an artery is narrowed by plaque build up, then the cross-sectional area…

A

is reduced, and the flow speed increases (Continuity Principle).

27
Q

The critical flow speed above which turbulence will occur (Vcrit) is given by:

A

Vcrit = constant x velocity / density x vessel radius

28
Q

The constant is called the _____, and for blood has a value of ____.

A

Reynold’s Number, ~1000