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Human physiology > Cardiac 1 > Flashcards

Cardiac 1 Flashcards

1
Q

What are the parts that make up the heart?

A

Chambers:
- Right atruim
- Left atrium
- Right ventricle
- Left ventricle

Valves:
- Pulmonary valve
- Mitral valve
-Tricuspid valve
- Aortic valve

Blood flow:
- Superior vena cave
- Pulmonary artery
- Inferior vena cava
- Pulmonary veins

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2
Q

What is the order that blood moves thru the heart to the body again?

A
  • SVC or IVC
  • Right atrium (thru AV vales ‘tricuspid’)
  • Right ventricle (out the pulmonary vale)
  • To the lungs
  • Left atrium (thru AV vales, bicuspid ‘mitral’)
  • Left ventricle (to aortic valve)
  • Out of the aorta
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3
Q

What are the 2 mechanical contractions of the heart?

A

Constitute as two pumps in a series

  1. Right ventricle propels blood to pulmonary circulation
  2. Left ventricle propels blood to systemic circulation
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4
Q

What is the volume output from the LHS to the RHS of the heart

A

~5 liters/min or ~70 ml/beat

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5
Q

What is the pressure generated in the LHS of the heart?

A

~4x RHS ~120 vs 30 mmHg

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6
Q

Where does gas exch take place in the lungs?

A

In the capillary beds of the lungs

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7
Q

What is the pressure of the blood like when it leaves vs enters he heart?

A

Leaves = enters circulation w high pressue

Enters = blood in venous circulation is present at low pressure

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8
Q

Where does gax exch take place in the body?

A

In the capillary beds of all body tissues

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9
Q

How does deoxygenated blood return to the heart?

A

Via the vena cavae

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10
Q

During moderate exercise what is the total cardiac output?

A

12.5L/min

Maximal is 25-30L/min

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11
Q

At rest what is the total cardiac output?

A

5 L/min

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12
Q

During exercise what happens to CO?

A

CO inc to meet the inc metabolic needs of the body –> particularly due to inc blood flow req to skeletal muscles

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13
Q

What is the formula for Cardiac Output?

A

Cardiac output = Heart Rate X Stroke volume
(litres/min) (beats/min) (ml/beat)

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14
Q

What happens to venous return during exercise?

A

Rises bc of compression of veins by contracting skeletal muscle → inc CO

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15
Q

What happens to SNS activity during exercise?

A

Inc by higher brain centres which initiate exercise & in part by receptors in exercising muscles → HR inc which leads to inc in CO

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16
Q

What happens to PNS activity during exercise?

A

Inhibited during exercise which inc in CO

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17
Q

What is cardiac hypertrophy

A

This develops with prolonged training → left ventricle enlarges, raising SV

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18
Q

What are the factors affecting HR?

A
  • Autonomic innervation
  • Fitness level
  • Age
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19
Q

What factor affects stroke volume?

A
  • Heart size
  • Gender
  • Duration of contraction
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20
Q

How are the aorta & large arteries structured?

A
  • Blood moves rapidly through the aorta & its arterial branches
  • Branches become thinner as they approach the periphery
  • In larger arteries, pressures are only slightly lower than in aorta
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21
Q

What is the structure of of the aorta & large arteries?

A

Thick walled, highly elastic

22
Q

What is the function of the aorta & large arteries?

A

Distribution (conduit), handles high pressure reservoir, forward propulsion

23
Q

How do arterioles contract & why?

A
  • Contraction of the circular muscle of small arterioles permits regulation of tissue blood flow & helps to control arterial blood pressure
  • Change from pulsatile (intermittent ejection from heart) to steady blood flow
24
Q

What are the layers of the aorta & large arteries?

A
  • Inner layer: Tunica intima
  • Middle layer: Tunica media
  • Outer layer: Tunica extrema
25
Q

What is the tunica extrema (outer layer) made up of?

A

Collagen fibres

26
Q

What is the tunica media (middle layer) made up of?

A

Smooth muscle cells & innervation

27
Q

What is the tunica intima (inner layer) made up of?

A

Endothelium that lines the lumen of ALL vessels

28
Q

What are the layers of the arterioles?

A
  • Inner layer: Tunica intima
  • Middle layer: Tunica media
  • Outer layer: Tunica extrema
29
Q

What is the structure of the arterioles?

A

Thick walled, muscular, highly innervated

30
Q

What is the function of the arterioles?

A

Tissue distribution flow, variable resistance

31
Q

Describe capillaries in general:

A
  • Many capillaries arise from each arteriole
  • Blood flow & velocity drop significantly across the capillary bed
  • Walls are only one cell thick
32
Q

What is the structure of capillaries?

A

Thin walled (single cell), lacking elastic tissue & smooth muscle

33
Q

What is the function of the capillaries?

A

Exchange

34
Q

What are the layers of the capillaries?

A
  • Single layer: Endothelium - endothelium that lines the lumen of ALL vessels
  • Lumen: very small (only large enough for 1 RBC to pass thru at a time)
35
Q

Describe the venules & veins in general:

A
  • On return to the heart from the capillaries, blood passes through venules & then veins
  • Return blood back to the heart (venous return)
  • Pressure decreases progressively until blood reaches heart
36
Q

What are the layers of the venules & veins?

A
  • Lumen = large lumen
  • Valves = facilitate movement of blood back to heart
  • Venous walls = thin layer of muscle & elastic tissue w thin outer layer
37
Q

What is the structure of the venules & veins?

A

Thin walled, some muscle & innervation, valves (unidirectional)

38
Q

What is the function of the venules & veins?

A

Reservour (capacitance); at rest approx 60% blood vol

39
Q

Insert tabe of comparison of blood vessel anatomy

A

Thanks xx

40
Q

Which blood vessel has the largest cross section?

A

The capillaries

41
Q

What are the blood vessels with the largest diameters?

A
  • Aorta > arteries > arterioles > capillaries
  • Veins > venules > capillaries
42
Q

What does the blood stream velocity depend on?

A

On the cross sectional area

‘River’ area:
- Area = 2cm^2
- Velocity = 5cm/s

‘Lake’ area:
- Area = 10cm^2
- Velocity = 1cm/s

Pls insert cross sectional area diagram here

43
Q

Constant flow rate (CO) = ?

A

Constant flow rate (CO) = blood flow velocity X cross-sectional area

44
Q

What are the determinants of blood flow (Q)?

A
  • Flow Q refers to the vol of fluid that passes a given cross-section of the vessel per unit time
  • Fluid velocity is inversely proportional to cross-sectional-area → the larger the area, the lower the velocity
45
Q

What is the formula for flow rate?

A

Flow rate = volume / unit time

46
Q

What is the formula for velocity?

A

Velocity = distance / unit time

47
Q

What happens if flow rate is constant?

A

Velocity is inversely proportional to cross-section area

i.e. slowest capillaries

48
Q

What are the factors that the relationship between pressure & flow (Q) depend on?

A

1 - Pressure = flow is proportional to the difference between inflow & outflow pressure (Pi - Po)

2 - Length = flow is inversely propotional to length of the vessel (L)

3 - Radius = flow is proportional to radius of the vessel (r^4)

4 - Viscosity = Flow inversely proportional to viscosity of the blood (ƞ)

49
Q

What was the law proposed to do with pressure & flow

A

Poiseuille’s Law was proposed more than a century ago to help describe the factors that affect flow rate thru a conduit (vessel)

50
Q

Pls insert the pressure & flow equation

A

Thanks x

51
Q

Which blood vessel have the greatest capacity to change their radius?

A

Arterioles

They can therefore influence resistance

52
Q

What us peripheral resistance’s relationship to pressure?

A
  • In electrical theory, resistance = voltage drop/electrical current flow (R=V/I)
  • In the vasculature, the equation for this is similar:

Resistance = Pressure difference / flow
R = Pi - Po / Q

Human physiology (43 decks)

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