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Anatomy 1 > Introduction to The CVS (Physiology) > Flashcards

Introduction to The CVS (Physiology) Flashcards

1
Q

Give a basic overview of the Cardiovascular system.

A

The CVS helps transport nutrients (glucose and amino acids) and oxygen to our tissues. It helps with the removal of waste products like carbon dioxide and urea.

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2
Q

Does having a transport system allow the development of other systems?

A

Yes

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3
Q

How does the Endocrine system dovetail alongside the Cardiovascular system?

A

It enables communication through the movement of hormones (chemical messengers) around the body.

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4
Q

How does the immune system work with the cardiovascular system?

A

It allows for the movement of inflammatory and immune modulators to sites of injury and infection.

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5
Q

Explain how the Cardiovascular system (W/ blood flow) is required for reproduction.

(4 points)

A

+ Penile erection in males is a hydraulic process requiring regulation of blood flow.

+ Gases and nutrients are transported to and from the foetus.

+ Blood flow maintains the placenta.

+ Blood flow allows for hormone signalling in pregnancy.

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6
Q

How is heat distributed around the body?

A

Warm-blooded organisms like ourselves generate heat. This heat is distributed around the body by the CVS.

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7
Q

How is temperature regulated by the CVS?

A

The CVS also regulates temperature by controlling blood flow through major organs and skin.

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8
Q

What is passive diffusion?

A

Passive diffusion is the simplest way to move. It is the undirected thermal movement of molecules, (e.g. random movement of a molecule).

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9
Q

Explain the link between time and distance in passive diffusion.

A

Time is proportional to distance squared.

> As diffusion distance increases, time taken increases exponentially.

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10
Q

Provide two examples of short distances for passive diffusion.

A

+ Across synapses in the nervous system, neurotransmitters move fast across very short distances.

+ The passive diffusion of substances from the capillaries to adjacent cells (down a concentration gradient) is very quick.

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11
Q

Provide two examples of distances that are too long for passive diffusion.

A

+ Across cartilage or around the left ventricle wall. Diffusion takes a very long time.

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12
Q

If an organism is larger than a few micrometres…

A

…It must overcome this basic problem by developing a cardiovascular system.

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13
Q

What does the heart need a lot of energy for?

A

+ To eject blood out of the heart with high pressure.

+ To create a pressure gradient (high out of the heart, low when entering). Allows for a double-circulation and movement of blood.

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14
Q

Where does pulmonary circulation take place?

  1. Describe the process briefly.
  2. What are the vessels connected to the right side called?
A

The right side of the heart.

  1. Deoxygenated blood enters the right atrium through the vena cava. It leaves the heart and goes to the lungs through the pulmonary artery.
  2. The vena cava (vein) and the Pulmonary artery.
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15
Q

Where does systemic circulation take place?

  1. Describe the process briefly.
  2. What are the vessels connected to the left side called?
A

The left side of the heart.

  1. Oxygenated blood is pumped from the lungs to the left atrium through the pulmonary veins. The blood is then pumped to the capillary bed in the body through the aorta.
  2. Pulmonary vein (vein) and the aorta (artery).
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16
Q

Provide two examples of passive diffusion of oxygen.

A

+ In the lungs, there is a passive diffusion of oxygen as it moves down it’s concentration gradient from the alveoli to the capillaries.

+ In the tissues, oxygen moves by passive diffusion from the capillaries.

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17
Q

Summarise the Cardiac Cycle.

A

The two sides of the heart work simultaneously.

  1. Both atria contract and blood flows into the relaxed ventricles.
  2. The atria now relax. The ventricles contract, expelling blood out of the heart.
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18
Q

What is the pressure like in the right side of the heart and why?

A

The right side of the heart is a low-pressure system (around 18-25 mmHg) because it only has to move blood through the lungs.

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19
Q

What is the pressure like in the left side of the heart (aorta) and why?

A

The left side of the heart pumps blood at a much higher pressure (>100mmHg) to the capillary bed of the body.

+ This is why the walls of the left ventricle are much thicker to generate that force and eject blood into the systemic circulation.

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20
Q

What is the pressure at the end of the systemic circulation? How does this difference help?

A

Pressures at the end of the systemic circulation are much lower (around 5mmHg).

This difference enables blood to flow around in a circulation.

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21
Q

What is systole?

A

A contraction phase. Focuses on contraction and ejection of blood.

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22
Q

What is diastole?

A

The relaxation phase. Relaxation of the heart is important to ensure it fills properly.

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23
Q

What happens to the heart tissue as a person gets older?

A

The heart tissue becomes stiffer and does not relax as much. The ventricles don’t fill as well which means that cardiac output is reduced.

It can ultimately lead to forms of heart failure.

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24
Q

What is the typical resting blood pressure?

A

120/80 mmHg

> 120 : Systolic

> 80 : Diastolic

25
Q

State the equation for Cardiac Output.

Add the units as well.

A

Cardiac output (litres/min) = Heart rate (bpm) x Stroke volume (ml)

CO = HR x SV

26
Q

What is cardiac output?

A

A measure of how much blood the heart can pump in a given time, usually measure in litres/minute.

(Typically 5 litres per minute at rest)

27
Q

Why is the range of output large?

A

The range of output is very large due to the iteration of two factors, rate and stroke volume.

28
Q

State the 3 main ways of controlling cardiac output and summarise them.

A
  1. Filling pressure (Starling’s law) states that if MORE blood enters the heart and the ventricle walls are STRETCHED, they will contract HARDER and expel MORE blood.

+ Increase in stroke volume.
+ This is an intrinsic property of heart muscle. The more blood that fills the heart, the more it ejects.

  1. The sympathetic and parasympathetic autonomic nerves.

+ The autonomic nervous system exerts control.
+ Sympathetic activity : INCREASES heart rate AND force of contraction
+ Parasympathetic activity : REDUCES heart rate.

  1. Chemical factors and hormones (for example adrenaline which binds to beta1 receptors on the heart to increase heart rate and force of contraction).
29
Q

How can blood flow be controlled?

A

By controlling the vasculature. Controlling the resistance of the vessels gives some control of blood flow.

30
Q

How is maximum heart rate typically measured?

A

220 - Age = Maximum heart rate

(Typically)

31
Q

Blood flow is…

A
  1. Proportional to pressure across blood vessel
  2. Inversely proportional to resistance of blood vessel.

^ Resistance = v Blood flow

32
Q

What is the equation for Blood flow?

A

Blood Flow= (Pa - Pv ) / Total peripheral Resistance (TPR)

Pa : Arteriolar pressure

Pv : Venous pressure (varies with location and posture, generally around 3-12 mmHg)

33
Q

What happens when blood vessels are constricted at a certain point?

A

Constriction will lead to reduction of flow (pressure downstream lowered) and increased pressure upstream.

34
Q

How is constriction of blood vessels potentially dangerous for a person with chronic high blood pressure?

A

Due to constriction, there may be poor blood flow to end organs. This can lead to organ damage (kidneys, liver or brain etc).

Lots of drugs that control blood pressure actually control resistance by dilating vessels, increasing flow and reducing pressure. This relationship is Darcy’s law.

35
Q
  1. What does the 120/80 mmHg actually refer to?
  2. What would happen to blood flow if blood pressure was 120/0 mmHg instead?
A
  1. Even when the heart is relaxed, there is still blood pressure which maintains blood flow constantly.
  2. If it went from 120mmHg to zero, the blood flow would stop and start.

+ Maintaining pressure during diastole allows continuous blood flow.

36
Q

Give a brief overview of the ARTERIES.

(Two points)

A

Large arteries (elastic vessels) can change volume and stretch under pressure.

They help convert the intermittent ejection pressure to a more constant, continuous flow.

37
Q

Give a brief overview of the ARTERIOLES.

(4 Points)

A

Resistance arterioles are the smaller arterial vessels that control arterial BP by determining total peripheral resistance (TPR).

They regulate local blood flow.

They provide resistance to blood flow by virtue of their smaller diameter, regulation of local blood flow.

These vessels innervate the main organs they control (supply with nerves).

38
Q

Give a brief overview of the CAPILLARIES.

(2 Points)

A

The capillaries are one-cell thick, exchange vessels.

They are where:
+ O2 and CO2 are exchanged.
+ It is also where glucoses diffuses across.
+ Where there is movement of water in and out of the interstitial fluid.
+ Lymph formation removal of metabolic waste.

39
Q

Give a brief overview of the VEINS.

(3 Points)

A

The veins (and small veins known as venules) are called capacitance vessels because at any given time, most of the blood is in them.

They are very compliant and not very muscular. They fill and expand passively as a result.

They control the filling pressure of the heart (by contracting slightly to inc amount arriving to the heart) and provide a reservoir of blood.

40
Q
  1. What is the clinical significance of the Myocardium (muscular tissue of the heart) & brain being under perfused?
  2. What has to be monitored as a result?
A

This creates potential clinical problems as they are vulnerable where a relatively moderate fall in blood perfusion is experienced, such as in angina, Myocardial infraction (MI), stroke, etc.

Cardiac output and blood flow need to be carefully monitored.

41
Q

Where is most of the blood distributed in our bodies?

A

The veins.

Systemic veins and venules serve as a reservoir of blood holding 65% of volume.

42
Q

As most of the blood is distributed in the veins, what would happen to them during exercise?

A

The veins would contract to shift some of the blood into the arteries, providing greater oxygen-carrying capacity where needed, e.g skeletal muscle or brain.

43
Q

Why does the pressure drop when the blood reaches the (1) arterioles?

(3 Points.)

A

(1) The arterioles are primary resistance vessels under sympathetic nervous system & hormonal control.

+ In order to regulate resistance to flow throughout the circulation. Determines the resistance to flow & total peripheral resistance.

+ Different arterioles can contract/relax to divert blood to selective organs or muscles depending on specific requirements.

44
Q

Why does the pressure drop when the blood reaches the (2) capillaries?

(4 Points.)

A

The pressure is very low in the capillaries.

+ Capillaries are weak vessels with thin walls; being the site of gas and nutrient exchange.

+ They don’t contract or control pressure.

+ Downstream of the capillaries, the pressure in the venules and veins remains lower.

45
Q

State the full equation for Blood Velocity. Provide the units.

A

Blood velocity (cm/s) = Blood flow (ml/s) / TOTAL cross-sectional area (cm^2)

46
Q

Describe blood velocity at the heart and arteries.

A

Very high

47
Q

Describe blood velocity at the arterioles.

A

Blood starts to slow down as it goes through the arterioles as they are resistance vessels which control blood flow and resistance to flow.

48
Q

Describe blood velocity downstream of the arterioles, at the capillaries.

A

Very low.

Allows for more time for the gas & nutrient exchange as the blood slowly moves through the capillaries.

49
Q

How can there be a gradual INCREASE IN BLOOD VELOCITY as blood flows from the capillaries into the venules and later the veins leading back to the heart?

(2 Points)

A

The total cross-sectional area for all the arterioles and capillaries is very high as there’s many millions of vessels.

As blood flows through this high cross-sectional area, total cardiac output spreads out into so many different capillaries that the velocity in EACH capillary is REDUCED.

50
Q

What happens to the blood velocity in the venous system (back to the heart)?

A

INCREASED velocity as the reverse happens.

All the blood funnels back into fewer and larger vessels so cross-sectional area is reduced.

Pressure is NOT recovered but the velocity is, so blood gets quickly back to the heart.

51
Q

Name the SIX layers present in the ARTERY wall (from the outside in)

A

1) Tunica adventitia
2) External elastic membrane
3) Tunica media
4) Internal elastic membrane
5) Tunica intima
6) Endothelium

52
Q

Name the FOUR layers present in the VEIN wall (From the outside in).

A

1) Tunica adventitia
2) Tunica media
3) Tunica intima
4) Endothelium

53
Q

What is the endothelium?

(2 Points)

A

The endothelium is the inner lining of the blood vessel.

It is a layer of single cells underlined by a sub endothelial layer, consisting of delicate connective tissue.

54
Q

What is the Tunica Intima?

(2 points)

A

Under the endothelium are some elastic fibres orientated longitudinally in the arterial and venous wall.

These consist of the inner layers of the vessel collectively known as the Tunica Intima.

55
Q

What is the Tunica Media?

(3 Points)

A

This is the middle layer containing vascular smooth muscle.

These muscle cells are orientated in a circular direction so that when they contract, they reduce the size of the lumen. They open it up when relaxing.

This affects resistance to blood flow.

56
Q

What is the Tunica Adventitia?

(2 Points.)

A

This is the third layer that contains nerve fibres, smaller blood vessels, etc; supplying the smooth muscle.

Sympathetic nerves innovate this area. They release noradrenaline which diffuses passively to the smooth muscle alpha-1 receptors, leading to vasoconstriction.

57
Q

Why is the endothelium so important?

(2 Points.)

A

The endothelium releases nitric oxide which relaxes the vessels (vasodilation).

There would be a constant balance between sympathetic noradrenaline in the alpha-1 mediated vasoconstriction and the nitric oxide mediated relaxation from the endothelium.

58
Q

Give a brief overview of the difference between veins and arteries/arterioles.

(2 Points.)

A

Veins have a similar structure but less muscle + fewer elastic fibres/inner acting sympathetic nerves.

The arteries are resistance vessels. The veins are the capacitance vessels.

Anatomy 1 (2 decks)

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