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P1: Card System > Introduction to CVS > Flashcards

Introduction to CVS Flashcards

1
Q

why do we need the CVS?

A

→pump blood through the lungs and carry oxygen
→transport nutrients to the muscles and organs
→circulate hormones and immune mediators
→connection to the lymphatic system
→ human reproduction
→ temperature regulation

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2
Q

what is passive diffusion?

A

→random, undirected thermal movement of molecules.

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3
Q

what is the equation for passive diffusion?

A

→ time needed to diffuse a given distance is proportional to the square of the distance: t ∝ d².

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4
Q

what is the main method of molecule movement within the CVS and what does it provide?

A

→CVS uses convection
→ movement by a pressure gradient
→ It provides fast and directional transport
→diffusion is still crucial for transport over short distances.

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5
Q

what is the significance of having pressure differences?

A

→output of blood at high pressure creates a pressure difference with distant blood vessels.
→This pressure difference drives blood flow.

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6
Q

where does cardiac output go?

A

→blood is distributed to various parts of the body, such as the kidneys, liver and GI

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7
Q

what are the brain and myocardium relative to other tissues?

A

→relatively under perfused.

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8
Q

what controls cardiac output?

A

→filling pressure (Starling’s Law)
→sympathetic and parasympathetic autonomic nerves
→chemical factors and hormones (eg. adrenaline)

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9
Q

equation for calculating cardiac output?

A

→Cardiac Output = Heart Rate x Stroke Volume

→CO = HR x SV

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10
Q

why are blood flow and blood pressure important ?

A

→Blood flow and blood pressure are critical for correct bodily functioning
→ linked in the proper distribution of blood

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11
Q

what happens if there is poor perfusion of the kidney?

A

→ renal failure and death

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12
Q

equation for calculating blood flow?

A

→Blood flow = (Pa - Pv)/resistance

→Pa is the pressure at the artery, while Pv is the pressure at the vein.

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13
Q

what is blood flow proportional to and inversely proportional to?

A

1) proportional to pressure across the blood vessel

2) inversely proportional to the resistance of the blood vessel

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14
Q

why does blood slow down in the capillaries?

A

→to allow for gaseous/nutrient exchange to occur.

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15
Q

equation for calculating blood velocity?

A

→Blood velocity (cm/s) = blood flow (cm³/s) / total cross-sectional area (cm²)

→To calculate cross-sectional area, we do the number of vessels times the πr² per vessel.

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16
Q

describe in series blood circulation

A

→same blood supply between organs
→lower perfusion pressures
→medically significant if the first organ is being underperfused

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17
Q

describe parallel blood circulation

A

→cardiac output is split up
→safeguards O₂ supply in organs
→most organs are supplied this way

18
Q

what are differences between the structures of arteries and veins?

A

ARTERIES:
→ thicker elastic wall to maintain blood pressure
→ have high pressure that ensures blood flows in one direction

VEINS:
→thinner elastic walls
→ have valves to ensure no blood backflow

19
Q

what are elastic vessels?

A

ELASTIC VESSELS: ARTERIES

20
Q

what are resistance vessels?

A

RESISTANCE VESSELS: ARTERIOLES

21
Q

what are exchange vessels?

A

EXCHANGE VESSELS: CAPILLARIES

22
Q

what are capacitance vessels?

A

CAPACITANCE VESSELS: VENULES AND VEINS

23
Q

where is most of the blood volume distributed?

A

→mostly found in large and small veins and venules. →Systemic veins and venules serve as a reservoir, holding about 65% of the volume.

24
Q

What do large arteries do?

A

→Large arteries accomodate stroke volume

→convert intermittent ejection into continuous flow

25
Q

What do resistance vessels do?

A

→Control arterial blood pressure and regulate local blood flow

26
Q

What do exchange vessels do?

A

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

27
Q

What do capacitance vessels do?

A

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

28
Q

What is the typical resting blood pressure

A

120/80 mmHg is typical resting blood pressure- the systemic pressure

29
Q

What are the pressures in the aorta and large veins?

A

Aorta >100 mmHg

Large veins 5-10 mmHg

30
Q

Recall the resting and exercising cardiac output

A

Rest 70/min x 70 ml = 5 litres/min

Exercise 180/min x 120 ml = 20 litres/min

31
Q

What happens if pressure at both ends are the same?

A

No flow if pressure at both ends is the same. The higher the pressure difference, the faster the flow

32
Q

Summarise the systolic and diastolic pressures in systemic and pulmonary circulation

A 
Systemic= 120/80
Pulmonary= 25/15
33
Q

How does venous pressure vary?

A

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

34
Q

What are the roles of venules/veins?

A

Control filling pressure of the heart & provide a reservoir of blood.
They can stretch and contract but do not as much.
Have a lot of blood at anytime

35
Q

Where does the main drop in pressure occur?

A

arterioles and even lower in capillaries

36
Q

How do arterioles control BP?

A

by determining total peripheral resistance (TPR)

37
Q

What do the endothelium release?

A

nitric oxide which relaxes the vessels leading to vasodilation

38
Q

What is vascular tone?

A

innervations all the time and is balanced by the parasympathetic Noxide.

Allows control of the dilation- held in the middle to react immediately

39
Q

What do the sympathetic nerves in the tunica adventitia do?

A

Sympathetic nerves in the tunica adventitia release noradrenaline which stimulates α1 receptors leading to vasoconstriction

40
Q

Where is the majority of blood volume at any given time?

A

Systemic veins and venules- 65%
Lungs-10%
Heart-10%
Capillaries-5%

41
Q

Where does the cardiac output go?

Cardiac output and oxygen consumption

A 
1. Liver &GI
Kidneys
Brain
Muscle
Other

Oxygen consumption

  1. Liver and GI
  2. Muscle
  3. Brain
  4. Kidneys

P1: Card System (16 decks)

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