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39 Cards in this Set
- Front
- Back
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what are the 5 main functions of the CVS? How are these functions achieved? |
1. transport of respiratory gases 2. removal of waste products 3. body temperature control 4. hormone transport 5. movement of immune system components Achieved by circulation |
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what are the 2 blood circuits? |
systemic and pulmonary |
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How is cardiac muscle able to contact in more than one direction? |
striated cells muscle is wrapped around the heart |
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name the 4 valves |
1. pulmonary semilunar valve (between pulmonary valve and right ventricle) 2. aortic semilunar valve ( between aortic valve and left ventricle) 3. left AV valve- bicuspid 4. right AV valve- tricuspid |
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when will blood flow into the second chamber? |
when the pressure in the 1st exceeds the pressure in the second |
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Describe the 5 steps in the cardiac cycle. |
1. blood flows into atria- this is continuous 2. opening of AV valves- blood flows into ventricle 3. atrial systole- allows ventricles to fill 4. ventricular systole- pressure increases, closing of AV valves, aortic/pulmonary valves open 5. Ventricular diastole- closure of aortic and pulmonary valves |
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Explain why cardiac muscle is referred to as myogenic |
it is able to generate its own AP at SA node (pacemaker) |
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How does the AP in the heart spread? |
from cell to cell via intercalated discs- they gap (nexus) junction |
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explain the depolarisation, plateau and repolarisation in the heart AP. |
depolarisation- high permeability to sodium ions plateau- small gNA, increased gCA and gK repolarisation- decreased gCa and increased gK |
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how are calcium ions re-uptaken into the SR? |
ATP driven Ca pump |
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describe the cardiac excitation pathway |
AP depolarizes atria, impulses delayed for around 100ms at the AV node. His-bundles and purkinje fibres are activated- cause ventricular activation |
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what controls heart rate? |
SA node |
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In an ECG what does the P wave show? |
atria depolarisation |
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In an ECG what does the QRS wave show? |
ventricle depolarisation |
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In an ECG what does the T wave show? |
ventricular repolarisation |
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What are the 4 applications of ECG? |
1. measure automaticity (HR, pacemaker) 2. measure conductivity (pathway, re-entry, block) 3. hypertrophy (Increased in R-wave amplitude) 4. Ischemic damage (location, size, progress) |
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what is the cardiac output defined as? |
amount of blood pumped by heart in 1 minute |
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What is the stroke volume defined as? |
volume of blood pumped each ventricle in 1 contraction |
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what is the ejection fraction? |
% of volume pumped out |
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why does systemic arterial pressure decrease by 33% between systole and diastole? |
due to vessel elasticity and peripheral resistance |
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what is the equation for calculating caridac output? |
CO= HR.SV |
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what 2 things do the autonomic nerves in the heart modify? |
1. rate of activation 2. contraction force |
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Describe Parasympathetic modulation |
ACh released from vagal nerves. ACh causes decreased Ca and increased K- therfore depolarisation is slower |
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describe sympathetic modulation |
NAd released postganglionic nerve terminal (beta-adrenoreceptors) Atria- SAN is increased therefore depolarisation is quicker and HR increases Ventricles- increased contraction force due to increased calcium |
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which type of ANS modulation is dominant at rest? |
parasympathetic |
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which type of ANS modulation is dominant during exercise? |
sympathetic |
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what is the method of feedback control for ANS modulation? |
Via afferents from baroreceptors in aortic arch and cartoid sinus |
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what is the equation for stroke volume? |
end diastolic volume (EDV) - End systolic volume (ESV) |
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what two factors effect cardiac output? |
Intrinsic modulation Autonomic NS modulation |
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Why is contractility important? |
1. heart can deal with variations in venous return 2. balancing outputs of the two sides of the heart |
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according to starling's law, what determines cardiac output? |
venous return |
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what three things do autonomic nerves modify? |
1. HR (chronotropy) 2. Contractile force ( Ionotropy) 3. Relaxation rate (Lusitropy) |
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what does sympathetic stimulation release? |
Catecholamines |
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what is stroke volume regulated by? |
1. peripheral resistance 2. ionotropy 3. EDV --> preload --> degree of stretch |
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How does peripheral resistance effect Cardiac output? |
increased peripheral resistance leads to decreased cardiac output. doesn't change a lot |
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what are the three common layers in blood vessels? |
1. tunica intima (endothelium) 2. tunica media ( smooth muscle + controlled by SNS) 3. Tunica externa ( fibrous connective tissue) |
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What happens if endothelium is compromised? |
fibrin deposited in connective tissue- causes plaque and decreased functionality |
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what is Laplace's law? |
T is directly proportional to pressure x radius |
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name the 7 factors that affect BP |
1. Blood volume 2. stroke volume 3. ejection velocity 4. elesticity 5. gravity 6. peripheral resistance 7. heart rate |
