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What is the primary function of the cardiovascular system in terms of protection?
What is the primary function of the cardiovascular system in terms of protection?
What occurs during the systole phase of the cardiac cycle?
What occurs during the systole phase of the cardiac cycle?
Which feature of cardiac muscle cells contributes to their unique contraction capability?
Which feature of cardiac muscle cells contributes to their unique contraction capability?
How are the two circuits of the cardiovascular system primarily differentiated?
How are the two circuits of the cardiovascular system primarily differentiated?
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Which statement accurately describes the myocardium?
Which statement accurately describes the myocardium?
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What does a higher systolic pressure indicate?
What does a higher systolic pressure indicate?
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Which component of the cardiac conducting system does not function in contraction but is essential for normal heart excitation?
Which component of the cardiac conducting system does not function in contraction but is essential for normal heart excitation?
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What is the resting membrane potential inside a neuron?
What is the resting membrane potential inside a neuron?
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What primarily drives the depolarization process in a neuron?
What primarily drives the depolarization process in a neuron?
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What restores the original membrane potential after repolarization?
What restores the original membrane potential after repolarization?
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Which of the following best describes the function of the SA node?
Which of the following best describes the function of the SA node?
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What happens during the repolarization phase of a neuron?
What happens during the repolarization phase of a neuron?
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What triggers the opening of more Na channels during depolarization?
What triggers the opening of more Na channels during depolarization?
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What is the primary role of the sinoatrial (SA) node in the heart?
What is the primary role of the sinoatrial (SA) node in the heart?
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Which condition could potentially lead to arrhythmias?
Which condition could potentially lead to arrhythmias?
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What formula represents cardiac output (CO)?
What formula represents cardiac output (CO)?
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What physiological change occurs when calcium ions flow into cardiac myocytes?
What physiological change occurs when calcium ions flow into cardiac myocytes?
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How is stroke volume (SV) defined in relation to the left ventricle?
How is stroke volume (SV) defined in relation to the left ventricle?
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What effect does the parasympathetic nervous system (PNS) have on heart rate?
What effect does the parasympathetic nervous system (PNS) have on heart rate?
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Which blood vessel type is primarily responsible for oxygen and nutrient exchange?
Which blood vessel type is primarily responsible for oxygen and nutrient exchange?
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What is the primary purpose of vasoconstriction in arterioles?
What is the primary purpose of vasoconstriction in arterioles?
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What factor influences the afterload that ventricles must overcome?
What factor influences the afterload that ventricles must overcome?
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What does the term preload refer to in cardiac physiology?
What does the term preload refer to in cardiac physiology?
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What role does the right atrium play in the circulatory system?
What role does the right atrium play in the circulatory system?
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What is the primary cause of cardiovascular disease?
What is the primary cause of cardiovascular disease?
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Which of the following describes normal healthy blood pressure?
Which of the following describes normal healthy blood pressure?
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What is a common symptom of ischemia affecting the heart muscle?
What is a common symptom of ischemia affecting the heart muscle?
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What occurs during a transient ischemic attack (TIA)?
What occurs during a transient ischemic attack (TIA)?
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Which component of blood is primarily responsible for oxygen and CO2 transport?
Which component of blood is primarily responsible for oxygen and CO2 transport?
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What is the function of vasodilators in blood pressure management?
What is the function of vasodilators in blood pressure management?
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What is a potential effect of untreated hypertension?
What is a potential effect of untreated hypertension?
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What component of blood comprises 55-58% of its total volume?
What component of blood comprises 55-58% of its total volume?
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Which blood type is known as the universal donor?
Which blood type is known as the universal donor?
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What is one cause of hemorrhages in the capillaries related to hypertension?
What is one cause of hemorrhages in the capillaries related to hypertension?
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Which type of leukocyte is primarily involved in combating infections?
Which type of leukocyte is primarily involved in combating infections?
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What does the term 'hemophilia' refer to in relation to blood components?
What does the term 'hemophilia' refer to in relation to blood components?
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Study Notes
Unit 12: Cardiovascular System
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Role:
- Transportation: Oxygen (O2) and carbon dioxide (CO2), nutrients, waste, hormones
- Regulation: Temperature (vasoconstriction and vasodilation), blood pressure in tissues
- Protection: Blood clotting, immune cells
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Circuits:
- Pulmonary: Blood travels to the lungs to pick up oxygen.
- Systemic: Delivers oxygen to the body.
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Heart Structure:
- Composed of cardiac muscle tissue
- Four chambers: 2 atria and 2 ventricles
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Cardiac Muscle Tissue:
- Cells have one to two nuclei, located centrally.
- Striated and use the sliding filament mechanism to contract.
- Large mitochondria, preventing fatigue.
- Intercalated discs contain desmosomes and gap junctions for efficient heart contractions. Gap junctions allow ions and action potentials to travel between cells, connecting muscle fibers.
- Contains specialized cells called nodes that stimulate their own action potential (autorhythmicity).
- Myocardium is involuntary.
Cardiac Cycle and Conducting System
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Cardiac Cycle: All events involved with blood flow through the heart during 1 heartbeat.
- Systole: Contraction phase
- Diastole: Relaxation phase
- Arterial blood pressure is measured as systolic/diastolic; Higher systolic pressure indicates stronger contraction, and higher diastolic pressure indicates increased resistance in the arteries.
Conducting System
- 1% of cardiac myocytes don't contract but have specialized features for normal heart excitation (nodes).
- Nodes form networks that contact cardiac muscle cells via gap junctions, initiating and spreading impulses throughout the heart rapidly.
- The heart spontaneously generates electrical signals; it doesn't need a signal from the brain to beat.
- The heart is innervated by both sympathetic and parasympathetic nerve fibers influencing heart rate.
Electrical Conduction
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Action Potential: There must be a change in ion concentration for an electrical current to move down a neuron. More Na+ and Cl– ions are in the interstitial fluid, and K+ ions are in the cytoplasm. This difference in concentration (concentration gradient) and the charge difference across the cell membrane (electrical gradient) polarize the cell. Resting membrane potential is -70mV inside the cell.
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SA Node: The heart's pacemaker. Cells have a fluctuating resting membrane potential (usually around -60mV) that spontaneously depolarizes. Sodium channels slowly leak Na+ into the cell; when it reaches -40mV, Calcium channels open causing further depolarization until +10mV; K+ channels then open which causes repolarization. These steps repeat as sodium slowly leaks back in.
Conducting System of the Heart
- Sinoatrial (SA) Node: Generates cardiac impulses.
- Atrioventricular (AV) Node: Passes impulses to the AV bundle.
- AV Bundle: Impulses travel down the interventricular septum.
- Bundle Branches: Divide into left and right bundle branches, stimulating the ventricles to contract.
Excitation of Cardiac Myocytes
- Cardiac myocytes must be stimulated by electrical currents.
- Myocytes contain channels (sarcoplasmic reticulum) to hold calcium ions, which initiate a depolarization action that spreads to adjacent cells. The calcium influx causes contraction.
Arrhythmias
- Irregular heart rhythm due to defects in the conduction system.
- Causes include coronary artery disease, hypertension, myocardial infarction, hyperthyroidism, defective heart valves, stress and drugs.
Cardiac Output
- Total amount of blood ejected from the left ventricle per minute.
- Formula: Cardiac Output (CO) = Heart Rate x Stroke Volume.
Heart Rate (Beats/min)
- Influenced by stress, exercise, blood ion concentrations, and the sympathetic and parasympathetic nervous systems.
- Sympathetic nervous system: Releases norepinephrine, increasing heart rate and force of contractions, related to the “fight-or-flight” response.
- Parasympathetic nervous system: Releases acetylcholine, decreasing heart rate and force of contractions, related to the “rest-and-digest” response.
Stroke Volume (mL/Beat)
- Stroke volume is the product of the stretch of the heart muscle. Larger the blood volume the higher the stretch. The pressure in the ventricles (preload) before contraction and the resistance in the arteries (afterload) during contraction proportionally influence the strength of the contraction and the amount of blood ejected in one beat.
Anatomy of the Blood Vessels
- Arteries: Carry blood away from the heart under high pressure. Contain elastic and muscle layers for vasoconstriction and vasodilation. Controlled by the autonomic nervous system.
- Veins: Return blood to the heart under low pressure. Contain valves to prevent backflow.
- Capillaries: Sites of oxygen and nutrient exchange between blood and body cells. Composed only of endothelial cells and precapillary sphincters, which regulate blood flow to tissues.
Circulatory Routes
- Deoxygenated blood enters the right atrium from the body via the superior and inferior vena cava.
- Right ventricle pumps blood to the lungs for oxygenation (pulmonary circulation).
- Oxygenated blood returns to the left atrium via the pulmonary veins.
- Left ventricle pumps blood to the body via the aorta (systemic circulation).
Vascular Resistance and Blood Pressure
- Sphygmomanometer: Measures blood pressure—normal healthy ≈ 120/80.
- Atherosclerosis: A primary cause of cardiovascular disease; plaque buildup in blood vessel walls increases resistance, decreases blood flow, and increases risk of clots.
Cardiovascular Disease
- Hypertension: sustained high blood pressure, can cause damage over time (enlarged heart, arrhythmias, hypoxia).
- Stress on the heart, increased size to compensate for increased load, small hemorrhages in capillaries. Risk factors like Kidney damage, brain damage (stroke, retinal damage and lung damage).
Hemorrhage Classifications and Medication
- Hemorrhage: Classification of bleeding (capillary, venous, arterial)
- Medical Interventions: Diuretics to reduce blood volume, and vasodilators to decrease vascular resistance.
Angina/Myocardial Infarction
- Symptoms: Chest pain, pressure, tightness.
- Symptoms can last from minutes to hours.
- Caused by ischemia or hypoxia (lack of oxygen to heart muscle)
- Ischemia caused by decreased blood flow to coronary arteries (atherosclerosis -plaque build-up).
Stroke
- Transient ischemic attack (TIA): Short-lived stroke-like symptoms.
- Stroke: Ischemia (lack of O2) to the brain caused by blockage.
- Symptoms vary based on brain area affected.
Component of the Blood
- Plasma: Water, ions, vitamins, hormones, proteins, waste.
- Platelets: Cell fragments for blood clotting (coagulation).
- Erythrocytes (RBCs): Oxygen transport; contain hemoglobin.
- Leukocytes: White blood cells involved in the immune system.
Blood Types
- Blood type is determined by antigens on the surface of red blood cells.
- Incompatibility issues exist between different blood types, causing potential harm in certain transfusion situations.
- RH factor determines blood types as Rh+ or Rh-.
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Description
Explore the essentials of the cardiovascular system in this quiz. Learn about the heart's structure, its role in transportation, regulation, and protection, as well as the different circulatory circuits. Dive into the details of cardiac muscle tissue and how it functions effectively.
