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Questions and Answers
What effect does an increase in venous return have on heart rate?
What effect does an increase in venous return have on heart rate?
How does a rise in body temperature impact heart rate?
How does a rise in body temperature impact heart rate?
Which hormone is primarily responsible for increasing heart rate?
Which hormone is primarily responsible for increasing heart rate?
What is the most direct relationship between stroke volume and cardiac output?
What is the most direct relationship between stroke volume and cardiac output?
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Which pathway is activated during severe pain, leading to a decrease in heart rate?
Which pathway is activated during severe pain, leading to a decrease in heart rate?
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Which valve is located between the left atrium and left ventricle?
Which valve is located between the left atrium and left ventricle?
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What is the main function of the papillary muscles within the heart?
What is the main function of the papillary muscles within the heart?
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Which part of the conduction system of the heart is known as the pacemaker?
Which part of the conduction system of the heart is known as the pacemaker?
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What type of blood vessels function primarily as exchange vessels?
What type of blood vessels function primarily as exchange vessels?
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Which structure is responsible for the functional blood supply to the heart muscle?
Which structure is responsible for the functional blood supply to the heart muscle?
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What distinguishes end arteries from other arteries?
What distinguishes end arteries from other arteries?
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Which type of valve is found between the right ventricle and the pulmonary artery?
Which type of valve is found between the right ventricle and the pulmonary artery?
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What is the primary role of resistance vessels in the circulatory system?
What is the primary role of resistance vessels in the circulatory system?
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What components of the heart's conduction system are responsible for distributing electrical impulses throughout the ventricles?
What components of the heart's conduction system are responsible for distributing electrical impulses throughout the ventricles?
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Which layer of the heart wall is primarily responsible for making up the bulk of the heart's structure?
Which layer of the heart wall is primarily responsible for making up the bulk of the heart's structure?
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What is the role of the pericardial cavity?
What is the role of the pericardial cavity?
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Which statement accurately describes the location of the heart?
Which statement accurately describes the location of the heart?
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Which part of the heart is responsible for receiving blood returning from the body?
Which part of the heart is responsible for receiving blood returning from the body?
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What structure separates the atria from the ventricles?
What structure separates the atria from the ventricles?
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What is the function of the left atrium in the circulatory system?
What is the function of the left atrium in the circulatory system?
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Which part of the heart is primarily involved in pumping blood into the pulmonary trunk?
Which part of the heart is primarily involved in pumping blood into the pulmonary trunk?
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What is the primary function of arteries?
What is the primary function of arteries?
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Which layer of blood vessels contains a prominent sheet of elastin in large arteries?
Which layer of blood vessels contains a prominent sheet of elastin in large arteries?
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What is the primary difference between small arteries and arterioles?
What is the primary difference between small arteries and arterioles?
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How does the thickness of the tunica media change as the vessel diameter decreases?
How does the thickness of the tunica media change as the vessel diameter decreases?
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Which type of artery is classified as a muscular artery?
Which type of artery is classified as a muscular artery?
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What characteristic feature distinguishes large elastic arteries from other types of arteries?
What characteristic feature distinguishes large elastic arteries from other types of arteries?
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In which layer are smooth muscle cells more abundant in muscular arteries?
In which layer are smooth muscle cells more abundant in muscular arteries?
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What role do the layers of blood vessels serve in relation to high blood pressure in muscular arteries?
What role do the layers of blood vessels serve in relation to high blood pressure in muscular arteries?
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Which vessels are primarily composed of a thin tunica adventitia?
Which vessels are primarily composed of a thin tunica adventitia?
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What is the primary connective tissue feature of the tunica adventitia?
What is the primary connective tissue feature of the tunica adventitia?
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What is the primary role of the sinoatrial node (SAN) in cardiac function?
What is the primary role of the sinoatrial node (SAN) in cardiac function?
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Which of the following properties of cardiac muscle describes its ability to generate its own action potentials?
Which of the following properties of cardiac muscle describes its ability to generate its own action potentials?
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How do both atria function in terms of their physiological role in the heart?
How do both atria function in terms of their physiological role in the heart?
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Which factor predominantly influences heart rate under normal conditions?
Which factor predominantly influences heart rate under normal conditions?
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What is the function of purkinje fibers in the cardiac conduction system?
What is the function of purkinje fibers in the cardiac conduction system?
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What structure drains the first capillary network in the hepatic portal circulation?
What structure drains the first capillary network in the hepatic portal circulation?
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Which term refers to the ability of cardiac muscle to transmit the excitation signal efficiently?
Which term refers to the ability of cardiac muscle to transmit the excitation signal efficiently?
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What is the effect of the autonomic nervous system's sympathetic branch on cardiac rhythmicity?
What is the effect of the autonomic nervous system's sympathetic branch on cardiac rhythmicity?
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How many ganglia are estimated to be contained within the heart?
How many ganglia are estimated to be contained within the heart?
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What physiological characteristic describes the heart's ability to respond to stimuli?
What physiological characteristic describes the heart's ability to respond to stimuli?
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Study Notes
Cardiovascular System Overview
- The cardiovascular system comprises the heart and blood vessels.
- It's responsible for transporting blood throughout the body.
Parts of the Circulatory System
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Heart: A fist-sized muscular pump (250-300 grams).
- Located in the mediastinum, between the lungs.
- Rests on the superior surface of the diaphragm.
- Two-thirds of the heart lies to the left of the midsternal line.
- Anterior to the vertebral column, posterior to the sternum.
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Blood vessels:
- Arteries: Distribute blood away from the heart.
- Veins: Return blood to the heart.
- Lymphatic vessels: Part of the lymphatic system; involved in fluid balance.
Heart: Pericardium
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Pericardium: A double-walled sac surrounding the heart.
- Superficial fibrous pericardium: Outer layer of the sac.
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Deep two-layer serous pericardium: Inner layer.
- Parietal layer: lines the internal surface of the pericardium.
- Visceral layer (epicardium): lines the surface of the heart.
- The space between the layers is the pericardial cavity, filled with fluid.
- Functions: Protect, anchor, and prevent overfilling of the heart. Allows for friction-free movement during contractions.
Layers of Heart Wall
- Epicardium (visceral pericardium): Outermost layer.
- Myocardium: Thick middle layer of cardiac muscle.
- Endocardium: Innermost layer, a thin endothelial layer.
External Markings of the Heart
- Apex: Pointed inferior region.
- Base: Upper region.
- Coronary sulcus: Separates atria from ventricles.
- Anterior and posterior interventricular sulcus: Separates the right and left ventricles.
Heart Chambers
- The heart has four chambers:
- Right atrium: Receives blood from the body.
- Left atrium: Receives blood from the lungs.
- Right ventricle: Pumps blood to the lungs.
- Left ventricle: Pumps blood to the body.
Heart Valves
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Atrioventricular valves: Control blood flow between atria and ventricles.
- Tricuspid valve: Between right atrium and right ventricle.
- Mitral (bicuspid) valve: Between left atrium and left ventricle.
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Semilunar valves: Control blood flow out of the ventricles.
- Pulmonary valve: Between right ventricle and pulmonary artery.
- Aortic valve: Between left ventricle and aorta.
Conduction System of the Heart
- Specialized myocardial cells coordinate the heart's rhythmic contractions.
- Sinu-atrial (SA) node: Pacemaker of the heart.
- Atrioventricular (AV) node: Delays impulse transmission.
- Atrioventricular (AV) bundle: Conducts impulses to the ventricles.
- Bundle branches: Distribute impulses through the ventricles.
- Purkinje fibers: Rapidly spread the impulse through the ventricular walls.
Coronary Circulation
- Functional blood supply to the heart muscle itself.
- Coronary arteries: Branches off the ascending aorta.
- Coronary sinus (vein): Empties into the right atrium.
Blood Vessels
- Arteries: Distribute blood.
- Arterioles: Resistance vessels.
- Capillaries: Exchange vessels (microscopic tubes).
- Venules: Collect blood from capillaries.
- Veins: Conduct blood back to the heart.
- Anastomosis: Communication between neighboring vessels.
Histology of Blood Vessels
- Tunica intima: Innermost layer (endothelium).
- Tunica media: Middle layer (smooth muscle and elastic fibers).
- Tunica adventitia/externa: Outer layer (connective tissue).
Types of Arteries
- Large (elastic) arteries: Thick walls with elastic fibers for expansion.
- Medium (muscular) arteries: Distribute blood to various parts.
- Small arteries and arterioles: Control blood flow into capillaries.
Types of Veins
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Small to medium veins
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Tunica intima: Thin, contains endothelium, subendothelial layer, may have valves.
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Tunica media: Thin, contains smooth muscle, collagen, and some elastic fibers.
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Tunica adventitia: Well-developed. -Large veins
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Tunica intima: Thicker, prominent internal elastic lamina.
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Tunica media: Thinner, sparse smooth muscle, and connective tissue abundant.
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Tunica adventitia: Thick, contains longitudinal bundles of smooth muscle, spirally arranged collagen fibers and laminated elastic fibers.
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Types of Capillaries
- Continuous: Uninterrupted endothelial layer, most organs.
- Fenestrated: Pores (fenestrations) in the endothelial layer, kidney/endocrine glands.
- Sinusoidal: Wider spaces between endothelial cells, spleen/liver/bone marrow.
Venules
- Postcapillary venules similar to capillaries, but more contractile cells.
- Become muscular venules with a thicker tunica media and larger lumen compared to the overall thinness of the wall.
Systemic Circulation
- Blood flow from the left ventricle, throughout the body, then returns to the right atrium.
- Keeps tissues alive by supplying continuous blood supply.
Pulmonary Circulation
- Blood flow from the right ventricle to the lungs and back to the left atrium.
- Oxygenates blood.
Portal Circulation
- Part of systemic circulation; Blood passes through two sets of capillaries before draining into a systemic vein.
- Example: Hepatic portal circulation.
Physiology of Cardiovascular System
Objectives: Understand properties of cardiac muscle, the heart's pacemaker mechanism, cardiac output, arterial blood pressure, and vascular system/capillary circulation.
The Heart: Cardiac Muscle
- The heart is more than a pump; it secretes hormones (oxytocin, atrial natriuretic factor), contains 40,000+ ganglia, has an electromagnetic field, and has a connection to the brain.
- Cardiac muscle characteristics:
- Interconnected by gap junctions (syncytium) in the atria and ventricles. Physiologically, these act as a single unit.
- Properties: Rhythmicity (automaticity), conductivity, excitability, and contractility.
- The sino-atrial (SA) node acts as a pacemaker.
Myocardial Contractility
- Defined by the ability of the cardiac muscle to contract as a response to stimulus.
- +ve inotropy: Increases cardiac muscle contraction.
- -ve inotropy: Decreases cardiac muscle contraction.
- Frank-Starling Law: Within limits, myocardial contraction force is directly proportional to myocardial fiber length.
Factors Affecting Cardiac Rhythmicity
Heart Sounds and Murmurs
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Heart Sounds (Lup-Dup): Sounds caused by valve closure.
- Lup: Atrioventricular valve closure.
- Dup: Semilunar valve closure.
- Murmurs: Abnormal heart sounds.
Heart Rate
- Autorhythmicity: Heart's inherent ability to beat regularly.
- ANS Regulation: Sympathetic increases heart rate, parasympathetic slows it down.
- Normal Range: 60-90 beats per minute (average 75 bpm).
- Factors affecting Heart Rate: Age, sex, physical activity, and emotions.
Regulation of Heart Rate
Cardiac Output (COP)
- The volume of blood pumped by each ventricle per minute.
- It is controlled to maintain an adequate supply to tissues.
- COP = Stroke Volume × Heart Rate (factors that affect stroke volume: venous return, myocardial strength).
Arterial Blood Pressure (ABP)
- Definition: The pressure of blood against the arterial walls.
- Systolic BP: The pressure during ventricular contraction.
- Diastolic BP: The pressure during ventricular relaxation.
- Normal Range: 120/80 mmHg.
- Pulse pressure: Difference between systolic and diastolic.
- Factors affecting ABP: Blood volume, cardiac output, vessel elasticity, vasoconstriction, blood viscosity.
Regulation of Arteriolar Diameter
- Vasoconstriction (sympathetic): Reduces vascular capacity (increase ABP).
- Vasodilation (parasympathetic): Increases vascular capacity (decrease ABP).
Edema
- Definition: Abnormal fluid accumulation in the extracellular spaces.
- Causes: Increased capillary blood pressure, decreased colloid osmotic pressure, lymphatic obstruction.
Factors Maintaining Normal Arterial Blood Pressure
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Description
Explore the components and functions of the cardiovascular system, including the heart and blood vessels. This quiz covers the anatomy of the heart, the structure of blood vessels, and the role of the pericardium. Test your knowledge on this essential body system!
