Cardiovascular System Flashcards Preview

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Flashcards in Cardiovascular System Deck (51)
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What is Hydrostatic Pressure?

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)


What is the Frank-Starling Mechanism?

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


What links Mean Arterial Pressure with Peripheral resistance?

MAP = Q x Total PR


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

The abdominal organs and kidneys


Explain what Korotkoff sounds are

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


What is the difference between Diastole and Systole?

Diastole - Ventricular relaxation, and blood filling


Systole - Ventricular contraction, and blood ejection


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

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




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

Diastolic pressure + 1/3 (Pulse pressure)


Pulse Pressure = Difference between systolic and diastolic pressure


At what distance does diffusion become very slow?



Explain the role of baroreceptors in the maintainance of blood pressure

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


What type of cells does the lymph fluid contain?



Dendritic cells


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

The radius of the blood vessel

As its increased by the power of 4


Describe the permeabilities of cellular membranes

Permeable to water

Impermeable to solutes/ions


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


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

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)


How is the SA node innervated?

Parasympathetic = Vagus Nerve

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



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


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


Describe the mechanism of contraction of the ventricular cardiomyocytes

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


Describe the intrinsic (local) regulation of blood flow

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


How does the skeletal muscle pump work in the body?

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


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

Short term - Baroceptors firing


Long term - Kidneys (Renin-Agniotensin System)


What are the meanings of the points in an ECG?

P = Atrial Depolarization

QRS = Ventricular Depolarisation

T = Ventricular Repolarization

PQ = Atrial Contraction

QT = Ventricular Contraction


What do the kidneys do when cardiac output decreases?

Increases water reabsorption to increase the blood volume


What is the Neural effect on arterioles?

Symapthetic nerves cause noradrenaline to vasoconstrict or dialate arterioles


No parasympahtetic innervation


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


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

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


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


What is the difference between Veins and Arteries

Veins - Take blood towards the heart


Arteries - Take blood away from the heart


What is an Osmole?

One osmole is 1 mole of a solute in 1L


Eg, 1M Glucose = 1 Osm

1M NaCL = 2 Osm

1M MgCl2 = 3 Osm


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

A long refractory period


What occurs to baroreceptors during exercise?

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


What are the two major functions of the lymphatic system?

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


Maintainance of the immune system


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