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Cardiovascular system > Intro to the CVS > Flashcards

Intro to the CVS Flashcards

1
Q

What are the 6 main reasons why we need the CVS?

A
  1. Pump blood through Lungs & carry Oxygen, take away CO2
  2. Transport nutrients to muscle and organs, take away waste and metabolises
  3. Circulates hormones & immune mediators
  4. Connection to lymphatic system
  5. Human reproductive system (in ejection/ejaculation)
  6. Temperature regulation (need to distribute heat)
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2
Q

What is passive diffusion?

A

Random movement of undirected thermal movement of molecules

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3
Q

What is the time needed to diffuse a given distance proportional to?

A

square of the distance

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4
Q

At what distance does diffusion become time consuming?

A

> 1mm, then diffusion becomes inappropriate as the mode of transport throughout the body

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5
Q

Time taken to diffuse across 0.1 um

A

0.005 ms, e.g. Synapse

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6
Q

Time taken to diffuse across 10 um

A

50 ms, e.g. from Capillary to Cell

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7
Q

Time taken to diffuse across 1 mm

A

8 min, e.g. through Cartilage

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8
Q

Time taken to diffuse 1 cm

A

13 hours, e.g. through Left Ventricle Wall

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9
Q

what does pressure difference drive?

A

blood flow

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10
Q

Systole

A

Contraction

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11
Q

Diastole

A

Relaxation

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12
Q

Cardiac output=

A

Volume of blood ejected from the heart per minute, normally around 5 litres/min

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13
Q

What is the main method of molecule movement within the CVS?

A
  • CVS uses convection (movement by a pressure gradient)
  • provides fast and directional transport
  • diffusion still crucial for transport over short distances
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14
Q

Distribution of cardiac output

A
  • Liver & GI: 25%
  • Muscle: 20%
  • Brain: 13%
  • Kidneys: 20%
  • Myocardium: 4%
  • Other: 18%
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15
Q

Oxygen consumption at rest

A
  • Liver & GI: 30%
  • Muscle: 20%
  • Brain: 18%
  • Kidneys: 10%
  • Myocardium: 10%
  • Other: 12%
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16
Q

What two areas are of clinical significance to cardiac output distribution?

A
  • The brain and myocardium (muscular heart tissue)
  • Places are relatively under-perfused
  • Whenever there is a problem with blood supply, these two places are at risk (Stroke, Heart attack, angina, MI)
  • Therefore, need to carefully control cardiac output
17
Q

What three factors control cardiac output?

A
  1. Filing pressure (Starling’s law)
  2. Sympathetic and parasympathetic autonomic nerves
  3. Chemical factors & hormones (adrenaline)
18
Q

What is the equation for calculating cardiac output?

A
  • Cardiac output = heart rate x stroke volume

- CO = HR x SV

19
Q

Why are blood flow and pressure important?

A
  • Blood flow and pressure are critical for correct bodily functioning
  • Because they are linked in the proper distribution of blood
  • E.g. if there is poor perfusion in the kidneys: could cause renal failure and death
20
Q

Blood flow is…

A
  1. Proportional to pressure across blood vessel

2. Inversely proportional to resistance of blood vessel

21
Q

What is the equation for calculating blood flow?

A
  • Blood flow = (Pa -Pv) / resistance
  • Pa is the pressure at the artery
  • Pv is the pressure at the vein
22
Q

BP for Systemic circulation

A

120 (systolic) / 80 (diastolic)

- high pressure to pump around the body

23
Q

BP for Pulmonary circulation

A

25 (systolic) / 15 (diastolic)

- low pressure allows gas exchange

24
Q

What type of vessels are arterioles?

A

Resistance vessels

- They control arterial BP by determining total peripheral resistance (TPR)

25
Q

Why does blood slow down at the capillaries?

A

The velocity of blood is much slower at the capillaries to allow for gaseous/nutrient exchange to occur

26
Q

What is the equation for calculating blood velocity?

A
  • Blood velocity (cm/s) = blood flow (cm3/s) / cross sectional area (cm2)
  • To calculate cross sectional area, do a number of vessels x (pi r squared) per vessel
27
Q

Describe how dual circulation can be in parallel or in series?

A 
•	IN SERIES (PORTAL):
- Same blood supply between organs 
- Lower perfusion pressures 
- Medically significant if the first organ is being under perfused 
•	IN PARALLEL:
- Cardiac output is split up 
- Safeguards O2 supply in organs 
- Most organs are supplied this way
28
Q

Difference between structure of arteries and veins

A

• ARTERIES:
- Thicker elastic wall to maintain blood pressure
- Have high pressure that ensures blood flow in one direction
• VEINS:
- Thinner elastic walls
- Have valves to ensure no blood backflow

29
Q

ELASTIC VESSELS: ARTERIES function

A

Large arteries accommodate stroke volume and convert intermittent ejection into continuous flow

30
Q

RESISTANCE VESSELS: ARTERIOLES function

A

Control arterial blood pressure and regulate local blood flow

31
Q

EXCHANGE VESSELS: CAPILLARIES function

A

Nutrient delivery to cells and tissues for water and lymph formation, and removal of metabolic waste

32
Q

CAPACITANCE VESSELS: VENULES AND VEINS function

A

Control the filling pressure and provide a reservoir of blood, so the veins can constrict and send blood to the heart if needed

33
Q

Distribution of blood volume

A
  • Small veins and venues: 24%
  • Capillaries: 5%
  • Arteries: 10%
  • Heart: 10%
  • Lungs: 10%
  • Large veins: 24%
  • Systemic veins and venues serve as a reservoir holding 65% of volume
34
Q

Two types of circulation?

A
  1. Systemic circulation

2. Pulmonary circulation

35
Q

Systemic circulation

A

Takes oxygenated blood and nutrients (e.g. glucose) around the body and removes waste like amino acids and lactate

36
Q

Pulmonary circulation

A

Takes oxygen from lungs and releases carbon dioxide into the lungs

Cardiovascular system (16 decks)

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