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ADDITIONAL PHYS 1 > Intro to CVS > Flashcards

Intro to CVS Flashcards

1
Q

What are the two types of circulations?

A
  1. systemic circulation - O2 and nutrients around the body + removal of waste
  2. pulmonary circulation - O2 from lungs and CO2 released into the lungs.
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2
Q

Why do we need a Cardiovascular system?

A
  1. PUMP BLOOD THROUGH LUNGS AND CARRY OXYGEN
  2. TRANSPORT NUTRIENTS TO MUSCLES ADN ORGANS
  3. CIRCULATES HORMONES AND IMMUNE MEDIATORS – Can use CVS as a means of signalling. E.g. hormone released and target is far away or immune system links up all the areas in the body.
  4. CONNECTION TO LYMPHATIC SYSTEM – Regulates balance of water in blood in interstitial (tissue fluid) and in the cell. Fluid compartment with immune cells in it.
  5. HUMAN REPRODUCTION – CVS is needed. Blood flow for erection and to uterus and placenta. Hormonal signalling needed to reproduce.
  6. TEMPERATURE REGULATION – We can vasodilate to lose heat, and vasoconstriction to conserve heat.
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3
Q

How are things transported in the body?

A
  • Passive diffusion over short distances

- CVS uses convection (movement by pressure gradient).

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4
Q

What is passive diffusion and what is it’s equation?

A

•Passive diffusion is the random, undirected thermal movement of molecules.
t α d2
•Time need to diffuse a given distance is proportional to the square of the distance.

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5
Q

How does fluid move by convection?

A

• Heart uses metabolic energy to create pressure gradient – so fluid moves by convection

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6
Q

Which side of the heart has low pressure?

A

The right side is low pressured.

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7
Q

How is there a pressure difference in the heart?

A

Pressure difference is between the high pressure of blood leaving the heart by the aorta and low pressure of blood coming back to the heart by the vena cava.

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8
Q

What are the 4 valves? and where are they found?

A
  1. Mitral valve (between the left atrium and the left ventricle)
  2. Aortic valve - b/w left ventricle and aorta
  3. Tricuspid valve (between the right atrium and the right ventricle).
  4. Pulmonary valve - b/w right ventricle and the pulmonary artery.
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9
Q

What is systole and diastole?

A
  • Systole = contraction

* Diastole = relaxation

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10
Q

Where does the cardiac output go? and why?

A

CO mostly goes to (in order) the GI and liver, muscles, kidneys, myocardium and then the brain - O2 consumption is also in this order.

  • liver and the GI - nutrients from food adn detoxify.
  • Kidney get a lot since they filter the blood and effect the blood volume, etc.
  • in myocardium, Oxygen consumption is greater than the cardiac output distributed to it - Heart uses a lot of energy to transfer blood and nutrients around the body.
  • Myocardium and brain are relatively under perfused (other mechanism to ensure they are well perfused)– creates potential clinical problems e.g. angina, MI, Stroke triggered by relatively moderate fall in perfusion. – Need to carefully control cardiac output.
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11
Q

What is cardiac output? and what is its equation?

A
  • Cardiac output – How much blood per minute is expelled from the heart into the aorta
  • Cardiac output = Heart Rate X Stroke Volume
  • Stroke volume = amount of blood expelled when the left ventricle contracts) CO = HR x SV
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12
Q

Main factors that control cardiac output.

A
  1. Filling pressure (Starling’s law)
  2. Sympathetic and parasympathetic autonomic nerves
  3. Chemical factors and hormones (adrenaline) - Substances like hormones influence heart rate. Adrenaline would increase the heart rate and force of contraction.
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13
Q

When can stroke volume increase?

A

• Stroke volume can increase when heart pumps harder

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14
Q

What controls blood flow?

A

• Blood flow is:

  1. Proportional to pressure across blood vessel (increase in pressure = increase in blood flow)
  2. Inversely proportional to resistance of blood vessel (increase in resistance = decrease in blood flow)
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15
Q

What is Darcy’s law and what does it give us?

A

• Darcy’s Law gives us blood flow—
Blood flow = (Pa – Pv) ÷ Resistance
• (Pa – Pv) is the pressure in the artery – the pressure in the veins. (Finding the pressure difference).

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16
Q

How does the pressure in the systemic circulationa and the pulmonary circulation compare? and how does this help it?

A
  • Systemic circulation – this is to pump blood around the whole body.
  • Pulmonary circulation – which allows gas exchange. Also, vessels of the lungs are more delicate.
17
Q

What’s Starling’s law?

A

Starling’s law states that the more blood coming to the heart leads to more blood leaving the heart. As the left ventricle fills, the heart wall stretches, it allows the heart to contract harder. This is an intrinsic property of the heart muscle.

18
Q

How does sympathetic and parasympathetic autonomic nerves effect the cardiac output?

A

Sympathetic nerves release NA to the beta 1 adrenoceptors on the heart, which causes increase in heart rate and contractility (force of contraction). Parasympathetic nerves release ACh to the M2 receptors on the heart, which decreases electrical activity at the SAN, decreasing the heart rate.

19
Q

Role of the arterioles.

A
  • Arterioles enter the different organs, and they control blood flow being distributed and exerted
  • Arterioles are resistance vessels and control arterial BP by determining total peripheral resistance (TPR), this changes the blood flow – as they dilate and constrict. This may be a cause of hypertension.
20
Q

How does the area and the flow in capillaries help its role?

A
  • Large capillary area and slow capillary flow facilitates gas and nutrient exchange.
  • Bolus flow (one rbc at a time).
21
Q

Blood velocity equation.

A 
Blood Velocity (cm/s) = [Blood flow (cm3)] ÷ [Cross-sectional area (cm2)]
•	Cross-sectional area = Number of vessels X πr2
22
Q

Dual circulation of blood in the body.

A
  1. In SERIES (portal) circulation– Same blood supple between organs. E.g. blood moves from the intestines to the liver, as the liver removes toxins from the blood. (Liver also receives first hand blood from the hepatic artery). E.g. digestive system to the liver. The kidney (renal portal system) is another example. If there is any lower perfusion in the first organ in the portal system, then the second organ will be badly hit.
  2. (Mostly) In PARALLEL circulation – Cardiac output (from the aorta) is split up to supply individual areas (e.g. brain, gut etc) with blood. This safeguards oxygen supply in organs.
23
Q

Layers in blood vessel walls.

A

Three layer system:

  1. Tunica intima
  2. Tunica media
  3. Tunica externa
24
Q

Main functional groups of blood vessels, what do they do? and where are they found?

A
  1. Elastic vessels (large arteries, e.g. aorta)
    –During systole, it preserves the energy and constricts during diastole to keep the pressure high.
    –Accommodate stroke volume (amount of blood pumped from LV)
    – Convert intermittent ejection into continuous flow
  2. Resistance vessels (arterioles)
    – Control arterial BP
    – Regulate local blood flow
  3. Exchange vessels (capillaries)
    – Nutrient delivery to cells
    – Tissue water and lymph formation
    – Removal of metabolic waste
  4. Capacitance vessels (venules & veins)
    – Control filling pressure
    – Provide reservoir of blood
25
Q

What’s vascular tone?

A

Vascular tone – when the arterial wall is slightly contracted and slightly relaxed

26
Q

Where is blood volume mostly distributed?

A

• The majority of blood volume in the vessels is the systemic veins and venules (65% - 2/3), acting as a reservoir.

27
Q

Tunica intima

A
  • endothelial cells
  • basement membrane
  • surrounded by a thin membrane comprised of elastic fibres running parallel to the vessel
  • thinnest layer, supported by connective tissues and supportive cells
28
Q

tunica media

A
  • smooth muscle cells
  • elastin
  • connective tissues arranged circularly around the vessels
29
Q

tunica externa (adventitia)

A
  • entirely of connective fibres and surrounded by an external elastic lamina which functions to anchor vessels with other ones.
  • has nerve endings and vasorum (blood vessels)

ADDITIONAL PHYS 1 (25 decks)

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