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PA10309 > Cardiovascular System > Flashcards

Cardiovascular System Flashcards

1
Q

What is Hydrostatic Pressure?

A

The force that is exerted by the blood upon the capillary walls

The hydrostatic pressure changed as you go through the kidneys (decreases as you go)

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2
Q

What is the Frank-Starling Mechanism?

A

Causes the ventricles to contract with greater force when more blood is present (due to more tension)

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3
Q

What links Mean Arterial Pressure with Peripheral resistance?

A

MAP = Q x Total PR

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4
Q

At rest, where does most of the blood flow to?

A

The abdominal organs and kidneys

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5
Q

Explain what Korotkoff sounds are

A

Systolic - The artery is starting to open, so muffled sounds can start to be heard

Diastolic - The artery is practically open, so all sounds stop

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6
Q

What is the difference between Diastole and Systole?

A

Diastole - Ventricular relaxation, and blood filling

Systole - Ventricular contraction, and blood ejection

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7
Q

Describe the mechanism that is responsible for the triggering of the SA node

A

Na+ ions leak through F-type (funny) channels, whilst Ca2+ move in through T-type channels –> causing slow depolarization

Rapid depolarization occurs due to the openining of VG Ca2+ L-type channels

The reopening of K+ channels and the closing of Ca2+ channels cause repolarization

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8
Q

How do you calculate the mean arterial pressure (MAP)?

A

Diastolic pressure + 1/3 (Pulse pressure)

Pulse Pressure = Difference between systolic and diastolic pressure

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9
Q

At what distance does diffusion become very slow?

A

1mm

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10
Q

Explain the role of baroreceptors in the maintainance of blood pressure

A

Located in the aortic arch and carotid sinuses

They fire impulses proportionally to the blood pressure

The signals go to the medulla oblongata, which causes a change in HR/SV/Vessel Diameter via a negative feedback loop

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11
Q

What type of cells does the lymph fluid contain?

A

Lymphocytes

Macrophages

Dendritic cells

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12
Q

What factor has the greatest effect on blood flow and blood pressure?

A

The radius of the blood vessel

As its increased by the power of 4

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13
Q

Describe the permeabilities of cellular membranes

A

Permeable to water

Impermeable to solutes/ions

Therefore Osmosis determins the distribution of water between compartments in the body

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14
Q

Explain the differences in the structure of the arteries, arterioles, veins and capillaries

A

Arteries - Thick layer of smooth muscle and connective tissue

A large lumen

Arterioles - Contain a thin muscular wall, with smooth muscle that can contract to change the lumen size

A small lumen

Veins - Contain thin walls, and a large lumen

Contain VALVES

Capillaries - Has a single layer of endothelial cells to allow easy exchange of molecules (but not proteins)

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15
Q

How is the SA node innervated?

A

Parasympathetic = Vagus Nerve

Releases ACh, causing hyperpolarization (decreasing polarization) –> so reducing HR

Sympathetic

Releases Noradrenaline, causing an increase in depolarization –> increasing HR

Both of these systems are active at all times, just in different amounts

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16
Q

Describe the mechanism of contraction of the ventricular cardiomyocytes

A

Rapid Depolarisation - Rapid opening of VG Na+ channels

Prolonged Depolarization - This causes consistant contraction, and this is caused by the slow (but prolonged) opening of VG Ca2+ channels, and the closure of K+ channels

Repolarization - Opening of K+ channels

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17
Q

Describe the intrinsic (local) regulation of blood flow

A

Active Hyperemia - An increase in metabolism in the organ causes a decrease in [O2] an increase in [metabolites]

This causes vasodialation –> allowing more blood to go the organ

Flow Autoregulation - When there is a decrease in arterial pressure, there is a decrease in [O2]

Causing vasodialation –> allowing more blood to return to the organ

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18
Q

How does the skeletal muscle pump work in the body?

A

Contraction of the muscle causes blood to move through open valves in the veins –> and back to the heart

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19
Q

What are short/long term fixes to a change in blood volume?

A

Short term - Baroceptors firing

Long term - Kidneys (Renin-Agniotensin System)

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20
Q

What are the meanings of the points in an ECG?

A

P = Atrial Depolarization

QRS = Ventricular Depolarisation

T = Ventricular Repolarization

PQ = Atrial Contraction

QT = Ventricular Contraction

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21
Q

What do the kidneys do when cardiac output decreases?

A

Increases water reabsorption to increase the blood volume

22
Q

What is the Neural effect on arterioles?

A

Symapthetic nerves cause noradrenaline to vasoconstrict or dialate arterioles

No parasympahtetic innervation

23
Q

Briefly explain the composition of the blood (if put in a centrifuge)

A
24
Q

When using a stethoscope, what are the first and second sounds that occur when a heart beats?

A

1st - Closure of the AV valves (the onset of systole)

2nd - Closure of aortic/pulmonary valves (onset of diastole)

25
Q

What is the difference between Veins and Arteries

A

Veins - Take blood towards the heart

Arteries - Take blood away from the heart

26
Q

What is an Osmole?

A

One osmole is 1 mole of a solute in 1L

Eg, 1M Glucose = 1 Osm

1M NaCL = 2 Osm

1M MgCl2 = 3 Osm

27
Q

What system allows the ventricles to fill with blood before contracting (so stopping them from contracting quickly)

A

A long refractory period

28
Q

What occurs to baroreceptors during exercise?

A

Their limits are adjusted, allowing a greater BP to be achieved

29
Q

What are the two major functions of the lymphatic system?

A

Drain fluid from the tissues and return it to the cardiovascular system

Maintainance of the immune system

30
Q

What is the amount of blood in the body of an average 70kg person?

A

5.5L

31
Q

What does the movement of calcium into the cardiac muscles cause?

A

The release of calcium from the sarcoplasmic reticulum

32
Q

Why can hypertension cause a decrease in stroke volume?

A

As it causes the heart to undergo hypertension, causing the heart to become less compliant

So less blood can fit into the blood during ventricular filling

So SV is reduced

33
Q

Where is peripheral reistance primarily regulated?

A

The arterioles

34
Q

Explain what happens when the osmolarity of the extracellular fluid changes (when the intracellular is always 300mOsm/L)

A

When the extra/intracellular fluid is equal - There is no change to the cell –> this is known as isotonic

When the extracellular is smaller - Water flows into the cell due to the inside of the cell having a higher solute concentration –> this is known as hypotonic

When the extracellular is greater - Water flow out of the cell due to the outside of the cell having a greater solute concentration –> this is known as hypertonic

35
Q

Explain when the AV and aortic/pulmonary valves open/close

A

During ventricular ejection (systole) the aortic/pulmonary valves open due to the pressure in the ventricles being greater than the arteries

The AV valves open during ventricular filling (diastole) due to a greater pressure in the atria than the ventricles

36
Q

What is Colloid Osmotic Pressure?

A

This is where there is pressure exerted by the high conc of proteins in the plasma (compared to the ISF)

So these proteins draw water back into the plasma via osmosis

This only occurs in the capillaries due its semi-permeable nature

37
Q

How does intracellular oedema occur?

A

Metabolic system are depressed, causing reduced activity of Na+ channels –> resulting in a build up of intracellular sodium

This results in water moving into the cell

38
Q

Describe how the lymphatic system drains fluid and puts it back into the circulation

A

Fluid passes from the plasma –> ISF, and any excess fluid passes into the lymphatic system via lymph capillaries

The fluid then is scanned for infections by the lymph nodes

The lymphatic system contains many valves to ensure that the fluid has to move in one direction

The fluid is then returned to the blood in the neck (thoracic duct)

39
Q

Explain how filtraiton changed as you go through the capillaries

A

At the Arterial end - Hydrostatic pressure is high, and so causes a net outward filtration (as its pushing the fluid out)

At the Venous end - Hydrostatic pressure is low, so a net inwards filtration occurs (as the colloid osmotic pressure is too great)

40
Q

What would happen if the lymph nodes were blocked?

A

Liquid would not be able to move back into the blood, so the fluid would build up in the lymphatic system

41
Q

What causes a pulse in the artery?

A

The vibration of the artery from blood being ejected from the left ventricle

42
Q

Describe Poiseuille’s Law

A

Flow is proportional to the pressure gradient

  • Not just the pressure

And inversely proportional to the resistance

43
Q

What links HR and Respiration in ECGs?

A

Inspiration causes the HR to increase

Expiration causes the HR to decrease

44
Q

How is the exchange rate in the capillaries facilitated?

A

The flow rate is very low

The surface area is very large

45
Q

What is the hormonal effects on arterioles?

A

Vasoconstriction - Angiotensin / ADH

Vasodialation - Atrial Natriuretic Peptide (ANP)

46
Q

At rest, where does the most blood sit in the body?

A

The veins/venules

They act as a reservoir, with around 61% of the blood here at rest

47
Q

What are the 5 factors that can increase the central vein pressure (CVP) / venous return

A

Gravity

Respiratory pump

Reduced blood volume

Skeletal muscle pump

Contraction of central and peripheral veins (via sympathetic innervation)

48
Q

Describe what can occur when there is an increased hydrostatic pressure, or a decrease in colloid osmotic pressure

A

Hydrostatic - Causes water to leave the capillary at both the arterial and venular ends –> Causing a build up of liquid

This can be caused by heart faliure

Colloid Osmotic - Causes a lack of reabsorption of water back into the blood –> So lots of water is lost

This is caused by a reduction of plasma proteins

49
Q

Which side of the heart pumps blood to the majority of the body?

A

The left side

50
Q

What is osmotic pressure?

A

The pressure that is required to prevent osmosis

51
Q

What is the cornory sinus?

A

A single vein that drains deoxygenated blood from the heart cells back into the right atrium

PA10309 (9 decks)

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