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Human Anatomy Semester 2 > The Cardiovascular System > Flashcards

The Cardiovascular System Flashcards

1
Q

How many layers does the myocardium contain and what are their names?

A
  1. Epicardium (outer)
  2. Myocardium
  3. Endocardium (inner)
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1
Q

Describe the structure of the Myocardium

A

Surrounded by the Pericardium followed by the myocardial wall

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2
Q

Describe the structure of cardiac muscle tissue

A

Single, branched striated muscle cells known as cardiomyocytes

Mononucleated

Rich in mitochondria for contractions

Connected at intercalated discs containing gap junctions and desmosomes

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3
Q

How do T-Tubules enable heart contraction?

A

Rich in ion channels, transporters, receptors and pumps which allow for transmission of an action potential into the muscle cells.

Regulate intracellular calcium ion concentrations

Synchronise Calcium ion entry with release from the sarcoplasmic reticulum

Defined by sarcolemma-ryanodine receptor (SR) complex which is required for excitation-contraction coupling

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4
Q

What are the major heart structures and the valves connecting them?

A
  1. Right atrium and the tricuspid AV valve
  2. Right ventricle and the pulmonary artery (semilunar and pulmonary valves)
  3. Left atrium and the bicuspid atrioventricular valve
  4. Left ventricle and the aorta (Semilunar and aortic valves)
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5
Q

How are the sounds of a heartbeat produced

A

Characteristic ‘lub’ (s1) and ‘dub’ (s2) sounds are produced by the closure of valves
S1 - AV valve
S2 - Semilunar valve
3rd heart sound produced by blood flow turbulence

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6
Q

Describe the Left Coronary Artery

A

Passes anterior to the left atria

Divides into 2 main branches, the anterior interventricular and the circumflex branches

Left anterior descending artery (LAD) extends along the anterior IV sulcus - supplying blood to the walls of both ventricles

Circumflex branch runs along the coronary sulcus supplying the left ventricle and atrium walls

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7
Q

Describe the right coronary artery

A

Extends inferiorly to the right atria with small branches supplying the right atrium

Branches into the posterior IV and right marginal branches

Posterior IV branch follows the posterior IV sulcus, supplying the walls of both ventricles

Right marginal branches follow the coronary sulcus - supplying the right ventricle

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8
Q

What are anastomoses?

A

Specific regions of the heart receive blood from more than one arterial branch, where these meet are known as anastomoses

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9
Q

What is the purpose of anastomoses?

A

Provide an alternate route for blood to take if another becomes blocked

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10
Q

How is blood drained in coronary veins?

A

Deoxygenated blood drains from the coronary capillaries to coronary veins which transport blood into he coronary sinus.

This in turn drains into the right atrium

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11
Q

Which blood vessels supply the coronary sinus with deoxygenated blood?

A

The Great Cardiac Vein and The Middle Cardiac Vein

Great cardiac vein drains the anterior region while the middle cardiac vein drains the posterior region of the heart

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12
Q

Define a heartbeat

A

One period of diastole followed by one period of systole

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13
Q

How does the heart contract?

A

A wave of depolarization spreads from the sinoatrial node, across the atria to the atrioventricular node and then down the bundle of His and into the ventricle muscle via Purkinje fibres

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14
Q

What does an ECG measure?

A

An Electrocardiogram measures electrical changes in cardiac tissue during a heart contractile cycle

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15
Q

What is the sinoatrial node (SA node?)

A

In the upper region of the right atrium - Site of origin for action potential that stimulates heart muscle contraction

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16
Q

What is the atrioventricular node (AV node)?

A

Specialised for slow conduction - acts as an electrical filter, preventing the ventricles from contracting faster than they can fill with blood

17
Q

What are the Bundle of His and bundle branches?

A

Specialised for rapid conduction, delivering a wave of action potentials to the endocardium via the purkinje fibres

18
Q

Describe a typical ECG trace

A

P wave - atria depolarised

QRS - ventricles depolarised

T wave - ventricles repolarised

P-Q interval - Conduction time between SA node and ventricular depolarisation

S-T segment - Period of ventricular depolarization in plateau phase

Q-T interval - Time between ventricular depolarization and repolarisation

19
Q

How do phases of the cardiac cycle affect chamber presusre

A

Atrial contraction - plateau

Isovolumetric contraction - increase

Ventricular ejection - plateau

Isometric relaxation – decrease

Ventricular filling - plateau

20
Q

Describe the ventricular action potential

A

Na+ Channels open

Na+ Channels close

Ca2+ Channels open, fast K+ channels close

Ca2+ channels close, slow K+ channels open

Resting potential reached

21
Q

Describe the 4 actions of the cardiomyocyte action potential

A
  1. Rapid depolarisation due to Na+ influx upon the opening of fast Na+ channels
  2. Plateau due to Ca2+ inflow as voltage gatedcalcium ion channels open and some potassium channels close
  3. Repolarization due to K+ outflow when voltage gated potassium channels open
  4. Recovery phase
22
Q

Describe arterial structure

A

Elastic - Tend to be exposed to large pressure or volume changes

Muscular - Thicker smooth muscle layer in media

23
Q

Describe nutrient exchange in capillaries

A

Filtration - Fluid exits the capillary since hydrostatic pressure is greater inside than the blood colloidal osmotic pressure

No Net movement - Capillary pressure and blood osmotic pressure

Fluid re-enters capillary as hydrostatic pressure is lower than blood osmotic pressure

24
Q

What is Net filtration pressure (NFP)?

A

Determines overall direction of fluid movement into or out of the vessel

25
Q

What are the two types of fluid?

A

Intracellular fluid - Largest, the fluid within cells

Extracellular fluid - Everything outside of the cells including blood and lymph

26
Q

What is a normal blood pressure?

A

120/80 mmHg (Systolic/Diastolic pressure in the aorta)

27
Q

What is pulse pressure?

A

The difference between systolic and diastolic pressures, measured with the sphygmomanometer

28
Q

How do you calculate mean arterial blood pressure

A

MABP = Diastolic pressure + (pulse pressure / 3)

29
Q

How do blood vessels resist flow of blood?

A

Dependent on vascular compliance which is a combination of lumen diameter, viscosity of blood and blood vessel length

30
Q

How does lumen size affect resistance

A

Inversely proportional to the fourth power of the diameter.

The smaller the diameter the greater the resistance

1/d^4

31
Q

How does blood vessel length affect resistance

A

Directly proportional

32
Q

What is systemic vascular resistance (SVR)?

A

Resistance to flow in the vascular system. SVR is dependent on arterioles (most important), capillaries and venules

33
Q

How can MAP be controled?

A

The aorta (Elastic arteries) can stretch and recoil, increasing the volume of the vessel and therefore reducing the pressure

34
Q

What is preload?

A

End diastolic volume.

Directly proportional to the force of contraction during systole

35
Q

How can contractility be changed?

A

Using positive inotropic agents to increase and negative inotropic agents to decrease

36
Q

What are positive inotropic agents?

A

Include neurotransmitters and hormones of the sympathetic nervous system and beta adrenergic pharmacological agonists

37
Q

What are negative inotropic agents?

A

Include parasympathetic neurotransmitters, muscarinic agonists and calcium channel blockers

38
Q

What is afterload

A

Describes the pressures in the aorta and pulmonary trunk that need to be overcome by systole in order to pump blood into the systemic circulation

39
Q

What happens if afterload increases and preload is constant

A

Stroke volume will decrease, causing more blood to remain in the ventricles and the cardiac output will decrease

40
Q
A

Human Anatomy Semester 2 (3 decks)

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