Mastering Heart Failure Pathophysiology

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Define systolic dysfunction and diastolic dysfunction in the context of heart failure.

Systolic dysfunction refers to impaired cardiac contractility leading to a decreased ejection fraction. Diastolic dysfunction refers to impaired ventricular relaxation leading to decreased filling and increased ventricular pressure.

What are the main components of afterload?

The main components of afterload are vascular resistance and ventricular wall tension.

How does excessive afterload affect ventricular ejection and wall tension?

Excessive afterload may impair ventricular ejection and increase wall tension.

What is the formula for cardiac output?

Cardiac output = heart rate x stroke volume. Signup and view all the answers

What determines pre-load?

Pre-load is determined by venous return and end-diastolic volume (EDV). Signup and view all the answers

How does increased myocardial contractility affect cardiac output?

Increased contractility increases cardiac output independent of preload and afterload. Signup and view all the answers

What are the factors that influence myocardial contractility?

Myocardial contractility is influenced by Ca2+ levels, L-type channels opening facilitated by cAMP, and Na+/Ca2+ exchange inhibited indirectly by cardiac glycosides. Signup and view all the answers

What is the New York Heart Association (NYHA) classification of heart failure?

The NYHA classification of heart failure categorizes patients based on their symptoms and limitations in physical activity. Signup and view all the answers

Describe Class II heart failure according to the NYHA classification.

Class II heart failure is characterized by slight limitation of physical activity. Patients are comfortable at rest, but ordinary physical activity results in fatigue, palpitation, and shortness of breath. Signup and view all the answers

Differentiate between systolic and diastolic dysfunction based on ejection fraction.

Systolic dysfunction is characterized by a decreased ejection fraction, indicating impaired cardiac contractility. Diastolic dysfunction is characterized by a preserved ejection fraction, but impaired ventricular relaxation and increased ventricular pressure. Signup and view all the answers

What is the role of the capillary wall in regulating the movement of proteins and solutes?

The capillary wall is generally a barrier to proteins, but is permeable to water and most solutes. It is not a perfect filter, with the permeability for albumin being 1/1000th that of water. Signup and view all the answers

What is the oncotic pressure and how is it generated?

Oncotic pressure is generated by plasma proteins, predominantly by albumin and to a lesser extent by globulins. It is approximately 28mmHg and draws fluid into the capillaries. Signup and view all the answers

What is the role of hydrostatic pressure in capillary fluid dynamics?

Capillary hydrostatic pressure forces fluid out of the capillaries and into the interstitium. It decreases from the arterial end to the venous end, with a pressure of approximately 30-40mmHg at the arterial end and 10-15mmHg at the venous end. Signup and view all the answers

What is the role of the lymphatic system in controlling interstitial fluid?

The lymphatic system drains excess fluid from the capillaries, helping to control the volume of interstitial fluid. It also plays a role in controlling the concentration of proteins in interstitial fluids and is involved in the immune response. Signup and view all the answers

What factors affect venous return and why is it important for cardiac output?

Venous return to the heart is influenced by factors such as sympathetic innervation, muscle pumps, and postural changes in hydrostatic pressure. It is a major determinant of cardiac output, which is important for overall circulation. Signup and view all the answers

Explain the effect of decreased alveolar O2 on local alveolar blood flow in the lungs. What is the opposite effect observed in systemic vessels? What is the mediator responsible for this effect?

Decreased alveolar O2 reduces local alveolar blood flow in the lungs. The opposite effect observed in systemic vessels is increased blood flow. The mediator responsible for this effect is unknown. Signup and view all the answers

What are the major routes across capillary membranes for fluids, solutes, and larger molecules/proteins? Explain how Starling's forces contribute to fluid homeostasis and the net transcapillary movement of water across capillary beds.

The major routes across capillary membranes for fluids, solutes, and larger molecules/proteins are diffusion and bulk flow. Starling's forces, including hydrostatic and oncotic pressures, contribute to fluid homeostasis by balancing the movement of water between the capillaries and interstitial space. These forces determine the net transcapillary movement of water across capillary beds. Signup and view all the answers

What factors affect venous return and consequently determine cardiac output and blood pressure?

The factors that affect venous return and consequently determine cardiac output and blood pressure include blood volume, venous tone, skeletal muscle pump, and respiratory pump. Signup and view all the answers

What is the role of the lymphatic system in fluid homeostasis and the movement of water across capillary beds?

The lymphatic system plays a crucial role in fluid homeostasis by collecting excess interstitial fluid and returning it to the bloodstream. It helps maintain the balance of fluid between the capillaries and interstitial space, preventing edema and contributing to the movement of water across capillary beds. Signup and view all the answers

Describe the process of capillary diffusion and its significance in nutrient and gas exchange.

Capillary diffusion is the net movement of nutrients, oxygen, and metabolic end products across capillary membranes. It is essential for the exchange of gases and nutrients between the blood and surrounding tissues. Through diffusion, these substances move from an area of higher concentration to an area of lower concentration, ensuring adequate supply to the tissues and removal of waste products. Signup and view all the answers