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Heart Anatomy and Physiology
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Heart Anatomy and Physiology
Heart Anatomy and Physiology
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1
Question
What is the heart?
Answer
A hollow, muscular organ located in the center of the thorax occupying the space between the lungs (mediastinum) and rests on the diaphragm. It pumps blood to the tissues, supplying them with oxygen and other nutrients. It weighs approximately 300g (10.6 oz).
2
Question
What factors influence the weight and size of the heart?
Answer
The weight and size of the heart are influenced by age, gender, body weight, extent of physical exercise and conditioning, and heart disease.
3
Question
What are the layers of the heart?
Answer
1. Endocardium - the inner layer, consists of endothelial tissue and lines the inside of the heart and valves. 2. Myocardium - the middle layer, made up of muscle fibers and is responsible for the pumping action, composed of specialized cells called myocytes. 3. Pericardium - the exterior layer encased in a thin, fibrous sac composed of two layers: - Visceral pericardium, which adheres to the epicardium, and - Parietal pericardium, which envelops the visceral pericardium.
4
Question
What is the purpose of the pericardial fluid?
Answer
The space between the two layers of the pericardium is normally filled with about 20mL of fluid that lubricates the surface of the heart and reduces friction during systole.
5
Question
What is the significance of the thickness of the heart chambers?
Answer
The thickness of the myocardial layer varies due to the workload required by each chamber. The myocardial layer of both atria is much thinner than that of the ventricles because there is little resistance as blood flows out of the atria and into the ventricles during diastole. The left ventricle is 2 or 3 times more muscular than the right ventricle due to the need to overcome high aortic and arterial pressures.
6
Question
What are the four chambers of the heart?
Answer
1. Right Atrium - receives venous blood returning to the heart from the superior vena cava, inferior vena cava, and coronary sinus. 2. Right Ventricle - distributes deoxygenated blood to the lungs via the pulmonary artery. 3. Left Atrium - receives oxygenated blood from the pulmonary circulation via four pulmonary veins. 4. Left Ventricle - distributes oxygenated blood to the rest of the body via the aorta.
7
Question
What is the function of the heart valves?
Answer
Heart valves allow the flow of blood in only one direction, composed of thin leaflets of fibrous tissue that open and close in response to the movement of blood and pressure changes within the chambers.
8
Question
What are the types of heart valves?
Answer
1. Atrioventricular valves - separate the atria from the ventricles (tricuspid and bicuspid valves). 2. Semilunar valves - composed of 3 leaflets, shaped like half moons (pulmonic and aortic valves).
9
Question
What are coronary arteries?
Answer
Coronary arteries supply arterial blood to the heart, originating from the aorta just above the aortic valve leaflets.
10
Question
What is cardiac electrophysiology?
Answer
Cardiac electrophysiology generates and transmits electrical impulses that stimulate contraction of the myocardium, allowing the ventricles to fill completely before ventricular ejection.
11
Question
What are the characteristics of specialized electrical cells in the heart?
Answer
1. Automaticity - ability to initiate an electrical impulse. 2. Excitability - ability to respond to an electrical impulse. 3. Conductivity - ability to transmit an electrical impulse from one cell to another.
12
Question
What is the sinoatrial node (SA Node)?
Answer
The primary pacemaker of the heart located at the junction of the superior vena cava and the right atrium, with an inherent firing rate of 60-100 impulses per minute.
13
Question
What is an electrocardiogram (ECG)?
Answer
A non-invasive graphic recording of the heart's electrical activity, reflecting the phase of the cardiac cycle in specific waveforms.
14
Question
What is the PR interval in an electrocardiogram?
Answer
The PR interval represents the time needed for sinus node stimulation, atrial depolarization, and conduction through the AV node before ventricular depolarization, measured from the beginning of the P wave to the beginning of the QRS complex. Normal duration is 0.12-0.20 seconds.
15
Question
What is cardiac action potential?
Answer
A brief change in voltage across the cell membrane of heart cells that stimulates the myocytes causing contraction due to the exchange of electronically charged particles.
16
Question
What is the refractory period in cardiac physiology?
Answer
The brief period immediately following the response of a muscle or nerve before it recovers the capacity to make a second response.
17
Question
What are cardiac biomarkers?
Answer
Specific enzymes released from myocardial cells that become necrotic from prolonged ischemia or trauma that leak into the interstitial spaces of the myocardium and are carried into general circulation, resulting in abnormally high levels in serum blood samples.
18
Question
What is myoglobin?
Answer
A protein which becomes elevated with any muscle damage, elevates within 1-4 hours from damage, peaks at 6-12 hours, and returns to normal within 1-2 days.
19
Question
What is troponin-1?
Answer
An enzyme specific to cardiac muscle that is released with ischemia and damage. It is the most consistent and reliable biomarker for cardiac muscle injury, beginning to rise within 4-6 hours, peaking at 18 hours, and taking a couple weeks to return fully to normal.
20
Question
What is the normal range for QTc interval in males and females?
Answer
Normal duration for QTc in males is 0.34 - 0.45 seconds and in females is 0.39 - 0.46 seconds.
21
Question
What is the formula for calculating cell membrane formation?
Answer
Cell membrane formation is calculated by adding the HDL, LDL, and 20% of the triglyceride level.
22
Question
What is Low-Density Lipoprotein (LDL)?
Answer
Low-Density Lipoprotein (LDL) is the primary transporter of cholesterol and triglycerides into the cell, which results in deposition on the walls of arterial vessels.
23
Question
What is High-Density Lipoprotein (HDL)?
Answer
High-Density Lipoprotein (HDL) transports cholesterol away from the tissue and cells of the arterial wall to the liver for excretion.
24
Question
What are triglycerides composed of?
Answer
Triglycerides are composed of free fatty acids and glycerol, stored in adipose tissue and are a source of energy.
25
Question
What factors can elevate triglyceride levels?
Answer
Triglyceride levels can be elevated by diabetes, alcohol use, and obesity.
26
Question
How do triglyceride levels correlate with LDL and HDL?
Answer
Triglyceride levels have a direct correlation with LDL and an inverse correlation with HDL.
27
Question
What is Brain Natriuretic Peptide (BNP)?
Answer
Brain Natriuretic Peptide (BNP) is a neurohormone that helps regulate blood pressure and fluid volume, primarily secreted from the ventricles in response to increased preload.
28
Question
What role does C-Reactive Protein (CRP) play in the body?
Answer
C-Reactive Protein (CRP) is produced by the liver in response to systemic inflammation and plays a role in the development and progression of atherosclerosis.
29
Question
What is homocysteine, and why is it significant?
Answer
Homocysteine is an amino acid linked to the development of atherosclerosis because it can damage the endothelial lining of arteries and promote thrombus formation.
30
Question
What are the potential risks associated with elevated homocysteine levels?
Answer
Elevated homocysteine levels indicate a high risk for coronary artery disease (CAD), stroke, and peripheral vascular disease.