Filtración glomerular | Filtración glomerular fisiología | Filtración glomerular animación
Understanding Renal Physiology
Introduction to Renal Function
- The video introduces the importance of renal physiology, emphasizing the need to understand kidney functions after discussing their structure in a previous video.
- It highlights that plasma filtration in the renal corpuscle initiates a series of processes within nephrons essential for maintaining ideal substance concentrations in the body.
Mechanisms of Filtration
- Filtration is regulated by capillary pores, proteins, and glomerular cells, alongside hydrostatic and oncotic pressure gradients.
- As blood passes through glomerular capillaries, dissolved substances face an endothelium with sufficiently large pores allowing most plasma components to exit.
Glomerular Structure and Filtration Process
- A detailed view of glomerular structures shows how plasma is filtered: it must pass through endothelial pores, basal membrane proteins, and podocyte diaphragms before entering Bowman's capsule as filtrate.
- The resulting fluid is termed glomerular filtrate or ultrafiltrate, constituting about 20% of circulating plasma with an average filtration rate of 120 mL/min.
Composition and Characteristics of Filtrate
- The filtrate closely resembles plasma but contains minimal protein due to the negative charge on basal membrane proteins preventing significant protein passage.
- Substances bound to plasma proteins remain in capillaries while only small amounts like albumin can occasionally filter out due to specific conditions.
Forces Influencing Filtration
- The video explains that filtration rates vary between afferent and efferent arterioles due to two main forces: hydrostatic pressure (favoring filtration) and oncotic pressure (opposing it).
- Hydrostatic pressure inside glomerular capillaries drives plasma outwards while opposing pressures from Bowman's capsule liquid resist this flow.
Pressure Dynamics in Glomeruli
- Hydrostatic pressure results from systemic arterial blood pressure promoting filtration; conversely, pressures within Bowman's capsule work against this process.
Understanding Glomerular Filtration
Protein Pressure in the Glomerulus
- The protein pressure within the capsule space of the glomerulus is influenced by proteins present, creating a force that attracts water into this space and facilitates plasma exit. However, due to the low presence of proteins in this area, this force is considered negligible.
- In normal conditions, the highest pressure is found in the capillary due to a greater concentration of proteins. For effective filtration, hydrostatic and protein pressures must be balanced such that forces favoring filtration exceed those opposing it.
Hydrostatic and Protein Pressures
- Average values for pressures are assigned for clarity: capillary hydrostatic pressure ranges from 50 to 60 mmHg while capsule hydrostatic pressure is between 10 and 20 mmHg. The total hydrostatic force calculated is approximately 40 mmHg, which supports filtration.
- The protein pressure in the capillary averages between 20 to 30 mmHg, while it is effectively zero in the capsule. This results in a total protein force of about 25 mmHg opposing filtration.
Effective Filtration Pressure
- The net effective filtration pressure can be calculated as approximately 15 mmHg (40 mmHg favoring - 25 mmHg opposing), which allows for initial plasma-like liquid formation during glomerular capillary filtration.
- It’s noted that effective filtration decreases as blood moves through glomerular capillaries towards the efferent arteriole, indicating a reduction in filtering capacity over distance.
Factors Influencing Filtration