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A & P - Cardiovascular system 2
Cardiovascular system -- week 2
39
Anatomy
Undergraduate 1
09/11/2012

Additional Anatomy Flashcards

 


 

Cards

Term
Where is the heart located?
Definition

Posterior to the sternum

Base of heart at the level of the 3rd costal cartilage

Slightly to the left (1.2 cms)

Apex at the 5th intercostal space

7.5 cms to the left

Rotated to the left

Anterior surface of heart is the right atrium and ventricle

 
Term
Parietal pericardium?
Definition
lines the inner surface of the pericardial sac
Term
Visceral pericardium 
Definition
covers the heart
Term
Three layers of the heart wall
Definition

Epicardium: Outer surface of the heart

Visceral peicardium

 

Myocardium: Muscle wall of the heart

Concentric layers of cardiac muscle

 

Endocardum: inner surface

Simple squamous epithelium

 
Term
How many septum, blood vessels & valves are in the heart?
Definition

Septum x 2

 

Blood vessels to and from the heart x 6

 

Valves x 4 

Chordae tendineae

Papillary muscles

Term
Describe relaxed ventricles
Definition

AV valves relaxed chordae tendineae are loose

Semilunar valves closed (stops back flow)

 
Term
Describe contracting ventricles
Definition

AV valves pushed shut by blood, chordae tendineae and papillary muscles stop them going into atria

 

Semilunar valves open

 
Term
What vessels are involved in coronary circulation?
Definition
Coronary arteries:
Right and left coronary arteries
 
Cardiac veins
Great cardiac vein
Coronary sinus
Term
What is coronary artery disease?
Definition

Blockage of coronary circulation

Reduced blood flow to the heart

Results in coronary ischemia

 
Term
What is the clinical term for a heart attack?
Definition
Myocardial Infarction
Term
Describe what occurs during a heart attack
Definition

Heart has its own blood supply (coronary arteries)

When this blood supply is blocked the heart muscle cells die from lack of oxygen

Heart attack

Myocardial infarction

 

Death of tissue this way 

Infarct

 

Most commonly from severe 

Coronary artery disease

 
Term
What is Atherosclerosis?
Definition

Vascular Disease

 

Atheromas, or fibro-fatty intimal plaques

Term
What occurs when a coronary artery is obstructed?
Definition

Depends on where the blockage is

 

Downstream from the obstruction dies from ischemia (loss of blood flow) and thus hypoxia (oxygen deficiency)

 

Temporary and reversible ischemia

 

Angina pectoris

 
Term
What are three investigations used for examining myocardial infarction?
Definition

ECG - Echo- cardiography

 

Cardiac enzymes

 

Troponin I or T

 

Creatinine kinase

 

Technetium pyrophosphate scanning

 

 
Term
Describe the relation of a heart beat and a pulse
Definition

Heart beat = 1 contraction of the heart

 

Pulse = the wave of blood forced out of the ventricles causing the artery walls to expand

 
Term
Describe impulse conduction through heart
Definition

1. The impulse begins in the pacemaker cells of the sinoatrial node and moves down along the internodal pathways in the interatrial septum (stimulates contractile cells of both atria)

2. Impulse spreads via cell-to-cell contact across the surface of the atria. Only affects atria not ventricles.

3. There is a delay at the atrioventricular node (bundle of His), which is important as the atria must contract before the ventricles do.
4. The impulse travels along the anterioventricular bundle in the interventricular septum. Then along the bundle branches to the Purkinje fibres 
5. The impulse travels to the ventricular myocardium and ventricular contraction begins (atrial contraction has stopped). Papillary muscles first. Purkinje fibres second. Starts at the apex and moves towards the base ensuring blood travels out the ventricles
 
Term
Tachycardia
Definition
Faster than normal heart rate (based on age and activity)
Term
Bradycardia
Definition

(brady = slowness and kardía = of the heart), 

In adults this is a resting heart rate below 60 bpm

 
Term
Describe an ECG
Definition

As the action potential moves through the heart the wave of depolarisation is strong enough to be detected on the surface of the skin

 
Placements of the ECG leads on the body affects the wave
 
Measures: Height of waves
Duration of waves
Relationship between different waves
Amount of depolarisation in P wave and QRS complex
E.G. Large QRS – enlarged heart
Smaller than normal electrical signal may mean the heart mass has reduced 
 
Term
What waves are measured on an ECG?
Definition

P wave – depolarisation of the atria. The atria begin contracting after the P wave

 

QRS complex – ventricles depolarise. Ventricles begin contracting after the R wave

 

Atrial repolarisation is not seen as it occurs during QRS (ventricular contraction)

 

T wave – ventricular repolarisation

 
Term
What are we looking for in an ECG?
Definition

Segments (extend from the end of one wave to the start of the next)

 

P-R interval – start of atrial depolarisation to start of ventricular depolarisation (QRS)

 

More than 200 msec = damaged conduction pathway

Q-T interval

 

Ventricular de- and re- polarisation

 

Cardiac arrhythmias

 
Term
4 phases of the cardiac cycle
Definition

Atrial systole - contraction

  Atrial diastole - relaxation

  Ventricular systole - contraction

  Ventricular diastole - relaxation

 
Term
Describe systole and diastole
Definition

Systole - contraction

Diastole - relaxation

 

Systole - high blood pressure in chambers

Diastole - low blood pressure in chambers

Term
What are the two main sounds with closing of heart valves
Definition

“Lubb” – Start of ventricular contraction, when atrio- ventricular valves close

 

“Dubb” – Start of ventricular filling when the semilunar valves close

 
Term
Cardiac output
Definition

the volume of blood pumped out by the ventricles in one minute

 

About 5-6 litres per minute in adults

 
Term
Stroke volume
Definition

The amount of blood pumped out of each ventricle with each contraction

 

SV = End-Diastolic volume minus End-Systolic volume

 
Term
End-Diastolic volume
Definition
Amount of blood in the ventricles at the end of ventricular diastole
Term
End-Systolic volume
Definition
Amount of blood in the ventricles at the end of ventricular systole
Term
How is cardiac output calculated?
Definition

Stroke Volume x Heart Rate = Cardiac Output

 

eg

80 mls x 75 bpm = 6000mls per minute (6 litres)

 
Term
What are the factors that influence cardiac output?
Definition

Heart rate affected by:

Autonomic innervation 

Hormones

 

Stroke volume affected by:

End-diastolic volume

End systolic volume

Term
What is Autonomic innervation?
Definition

Sympathetic and parasympathetic divisions of the autonomic nervous system innervate the heart via the cardiac plexus

 

Cardioacceleratory centre (sympathetic)

Cardioinhibitory centre (parasympathetic)

 
Term
What four hormones influence cardiac output?
Definition

Increase heart rate by their effect on the sinoatrial node:

Epinephrine

Norepinephrine

Thyroid hormone

 

Increase heart rate by their effect on the contractile muscle cells:

Epinephrine

 
Term
What is stroke volume?
Definition
is the difference between the End-Diastolic Volume and the End-Systolic Volume
Term
How is End-Diastolic volume influenced?
Definition

End-Diastolic Volume (amount of blood in a ventricle before it contracts) is influenced by:

1. Filling time - duration of ventricular diastole

Depends entirely on heart rate, fast = less filling time


2. Venous return – the rate of blood flow back to the heart

Velocity of blood flow

Pressure gradients

Sympathetic nerve activity

Skeletal muscle activity

Thoracic/abdominal pressure

Valves

 
Term
How is End-systolic volume influenced?
Definition

End-systolic volume (amount of blood in a ventricle after it contracts) influenced by:

1.Preload – the stretching of ventricular muscle cells during ventricular diastole (increase EDV, increased preload)

2. Contractility – the amount of force produced during a contraction (increased due to increased calcium entry into the cardiac muscle cells)

Sympathetic NS increases contractility (positive inotropic action)

Parasympathetic NS decreases contractility (negative inotropic action)

Hormones (e.g. Epinephrine) have positive inotropic actions

Drugs have positive inotropic actions (e.g. Dopamine)  and negative inotropic actions (e.g. Beta-blockers) 

3. Afterload – tension required to force open the semilunar valves (increased by any factor that decreases blood flow

Term
What is blood pressure?
Definition

The pressure exerted by blood on the walls of the blood vessels that contain it

 
Term
What is the difference between systolic and diastolic blood pressure and mean arterial pressure?
Definition

Systolic blood pressure (SBP) peak pressure in the arteries during cardiac systole

 

Diastolic blood pressure (DBP) minimum pressure in the arteries during cardiac diastole

Pulse pressure – difference between SBP and DBP

 

Mean arterial pressure (MAP) an estimate of the average blood pressure

 
Term
Normal arterial blood pressure:
Definition

SBP = 90-120 mm/Hg)

DBP = 60-80 mm/Hg

MAP = 70-95 mm/Hg

 
Term
Blood pressure is influenced by:
Definition

Vascular pressure gradients: pressure difference between the ends of a blood vessel

Vascular resistance: force that opposes the movement of blood through a vessel

Blood flow and velocity: volume and speed blood flows through a vessel

Venous return: amount of blood arriving at the right atrium each minute

Cardiac output and Heart rate

Baroreceptors: stimulated by changes in pressure

Chemoreceptors: stimulated by changes in checmicals

Vasomotor centre: controls blood vessel diametre

Autoregulation: local adjustment of blood flow (vasodilation)

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