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MEC322 > Cardiovascular system > Flashcards

Cardiovascular system Flashcards

1
Q

What are the functions of blood?

A
  1. Transportation of oxygen, carbon dioxide, nutrients, hormones, heat, and wastes.
  2. Regulation of pH, body temperature, and water content of cells.
  3. Protection against blood loss through clotting, and against disease through phagocytic white blood cells and proteins such as antibodies, interferons, and complement.
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2
Q

What two portions does whole blood consist of?

A
  1. Blood plasma – a liquid extracellular matrix that contains dissolved substances.
  2. Formed elements – which are cells (red blood cells or erythrocytes, white blood cells or leukocytes, an platelets) and cell fragments
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3
Q

What are the antigens on the surface of red blood cells composed of?

A

Glycolipids and glycoproteins

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4
Q

What are other names for red and white bloodcells?

A

Erythrocytes and leukocytes respectively.

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5
Q

What is the viscosity and pH value of blood?

A

5x thicker than water, with a pH range of 7.35-7.45

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6
Q

What is the procedure of collecting blood from veins called?

A

Venipuncture

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7
Q

When is arterial puncture required?

A

To evaluate efficiency of gas exchange at the lungs.

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8
Q

How is the mammalian heart composed?

A

Four pumping chambers: upper left and right atria, and lower left and right ventricles. This allows it to act as a double pump.

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9
Q

What is the difference between veins and arteries?

A

Veins flow towards the heart, arteries flow away from it. So not defined by oxygen levels. This is shown by the pulmonary vein and artery.

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10
Q

What are the three major changes in the heart wall with aging?

A

-change in the collagen content
conformational
-change in the type of fibrillar collagen (amount of type III collagen decreases and type I increases)
-increase in collagen cross-linking

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11
Q

Where are ventricles thickest and thinnest?

A

Thickest at equator and base of left ventricle (needs to pump blood to most of the body). Thinnest at left ventricular apex and right ventricular free wall.

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12
Q

What are the 5 stages of the cardiac cycle?

A
  1. Atrial systole
  2. Isovolumetric contraction
  3. Ventricular ejection
  4. Isovolumetric relaxation
  5. Ventricular filling
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13
Q

What happens during the atrial systole?

A
  • Mitral valve opens rapidly and semilunar valves is closed
  • Atria contract and pump blood
  • Ventricles, already partially filled from phase 5, receive last ~30% of blood, for a final resting volume of about 130mL.
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14
Q

What happens during the isovolumetric contraction?

A
  • The deceleration of flow reverses the pressure across the valve leaflets and causes them to close (mitral valve closure)
  • Semilunar valves is still closed.
  • Ventricles begin to contract. Ventricular muscle initially shortens a little, but intraventricular pressure rises rapidly(about 50 msec in adult humans). Ventricular volume unchanged.
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15
Q

What happens during the ventricular ejection?

A
  • Atrioventricular valves close but semilunar valves open.
  • Pressures in left and right Ventricle exceed pressures in Aorta (80mmHg) and Pulmonary Artery (10mmHg).
  • Ejection is quick at first, slowing down as systole progresses.
  • Amount ejected each ventricle per stroke at rest is 70-90mL.
  • About 50mL of blood remains in each ventricle at the end of systole
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16
Q

What happens during the isovolumetric relaxation?

A
  • All the valves close as ventricles relax
  • Pressure within ventricles drops below 120mmHg
  • This ends once Ventricular Pressure falls below Atrial pressure  Atrioventricular valves open.
  • The heart pump blood to rest of body.
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17
Q

What happens during the ventricular filling?

A
  • Atrioventricular valves open and semilunar valve close.
  • Ventricles is relaxed.
  • Ventricles passively fill with approximately 70% of their final volume.
  • As the ventricles fill, rate of filling decreases and the AV valves drift towards closing.
  • Atria expand and are filling.
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18
Q

What is the circulation system?

A

Heart> arteries > arterioles > capillaries > venules > veins > heart

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19
Q

Where do the right and left coronary arteries originate?

A

They branch off of the aorta and into smaller vessels.

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20
Q

What par of the heart do the cardiac veins supply with blood?

A

The coronary sinus and back to the right atrium

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21
Q

What is angina pectoris?

A

Heart pain when body is not receiving adequate oxygen.

22
Q

What is a myocardial infarction?

A

A heart attack, when blood supply to the heart is completely blocked and the muscle dies.

23
Q

What is the function of heart valves?

A

Control flow of blood from one chamber to another and prevent backflow.

24
Q

What are the two types of subdivisions of the autonomic nervous system?

A

Sympathetic and parasympathetic nervous systems.

25
Q

What is the parasympathetic nervous system?

A

From the medulla oblongata (vagus nerve). Branches to S-A and A-V nerves and secretes acetylcholine (slows rate). Parasym. activity increases/decreases heart rate.

26
Q

What is the sympathetic nervous system?

A

From celiac plexus to heart. Secretes norepinephrine and increases force of contractions.

27
Q

What does the cardiac control centre in the medulla oblongata do?

A

Maintains balance between the parasympathetic and sympathetic nervous systems.

28
Q

What do baroreceptors do?

A

Detect changes in blood pressure.

29
Q

How do ions in the blood effect blood pressure?

A

Excess potassium decreases blood pressure, excess calcium increases it.

30
Q

How does ADH effect blood pressure long term?

A

If blood pressure is too low ADH is increased, promoting water retention.

31
Q

What is the effect of vasoconstriction by agiontensin 2 on blood pressure?

A

ADH and aldosterone are secreted.
EPO (erythropoietin) is secreted by kidneys if blood volume is too low.
ANP is secreted if blood pressure is too high.

32
Q

What is angiotensin released in response to?

A

Renin, if sodium levels are too low.

33
Q

What is the function of endothelium in veins and arteries?

A

Prevents platelet aggregation and secretes substances that control the diameter of the blood vessel.

34
Q

What is the tunica media composed of?

A

Smooth muscle and connective tissue, innervated by sympathetic nerves.

35
Q

Wat is the tunica externa comprised of?

A

Vascularized connective tissue.

36
Q

How does C02 move into capillaries and how does blood pressure move molecules out?

A

Diffusion and filtration respectively.

37
Q

What are the 4 valve types in a mammalian heart?

A
  1. Tricuspid (right atrium>ventricle)
  2. Pulmonic (bicuspid) (right ventricle to pulmonary artery)
  3. Mitral (left atrium to ventricle)
  4. Aortic (left ventricle to aorta)
38
Q

Which valves are smilunar?

A

The aortic (three semilunar cusps) and pulmonary valves

39
Q

What characteristics do semilunar valves have?

A

Receive blood from ventricles and allow blood to be forced into the arteries. No tendineae.

40
Q

What is the composition of the semilunar cusps?

A

3 distinct layers: the fibrosa(~45%), spongiosa(~35%) and ventricularis(~20%). Lined with endothelial cells and has dense collagenous core adjacent to high pressure aortic side.

41
Q

What characteristics do atrioventricular valves (mitral and tricuspid) have?

A

Prevent backflow from the ventricles into atria during systole. They are anchored to the walls of the ventricles by chordae tendineae, which prevent the valves from inverting but have no effect on the opening/closing of the valves. These are attached to papillary muscles.

42
Q

What is valvular stenosis?

A

The tissue forming the valve leaflets becomes stiffer, narrowing the valve openin and reducing the amount of blood able to flow through. Can become so narrow that hear function is reduced.

43
Q

What is valvular insufficiency(/regurgitation /incompetence/’leaky valve)?

A

Leaflets don’t close properly, leaking blood backwards across valve. This backflow is referred to as ‘regurgitant flow’.

44
Q

What was the first replacement heart valve?

A

Hufnagel valve in 1952

45
Q

What are main disadvantages of mechanical and biological valves?

A

Mechanical: more thrombosis (clots)

46
Q

What are the three tissue types in blood vessels?

A
  1. Tunica interna
  2. Tunica media
  3. Tunica externa
47
Q

What are vasoconstriction and vasodilation?

A

The decrease and increase of the diameter of the blood vessel lumen.

48
Q

What are precapillary sphincters?

A

Regulate blood flow through capillaries.

49
Q

What is venous return?

A

The movement of blood from capillaries to venules to veins back to the atria of the heart. Aided by Skeletal muscle pump and respiratory pump (breathing).

50
Q

What is vascular resistance?

A

Opposition to blood flow due to friction between blood and walls of blood vessels. Depends on size of blood vessel lumen, blood viscosity, and total blood vessel length.

51
Q

What were the initial challenges of stents?

A
  • Initial stents had high metallic density -> high incidence of sub-acute stent thrombosis (ST)
  • Bulky and technically challenging to use, resulting in frequent failure in deployment and embolization
  • Still at a significant risk of in-stent restenosis (ISR)
52
Q

What are the key requirements of stents?

A
  • Resist a uniform radial force
  • Offer structural scaffolding to the arterial wall
  • Expand on a range of diameters

MEC322 (6 decks)

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