Efferent arteriole

Definition

The efferent arteriole is a blood vessel that carries blood away from the glomerulus of a nephron in the kidney. After filtration occurs in the glomerulus, the efferent arteriole plays a crucial role in regulating blood flow and pressure within the nephron and ultimately influences the formation of urine. It is also involved in maintaining the kidney's overall function by controlling the filtration rate.

5 Must Know Facts For Your Next Test

1. The efferent arteriole has a smaller diameter compared to the afferent arteriole, which helps maintain higher pressure in the glomerulus for effective filtration.
2. It branches into peritubular capillaries, which play an essential role in reabsorption and secretion processes within the nephron.
3. The resistance offered by the efferent arteriole affects glomerular filtration rate (GFR), influencing how much fluid and solutes are filtered into the Bowman’s capsule.
4. Hormones like angiotensin II can constrict the efferent arteriole, leading to increased GFR during situations like dehydration or low blood pressure.
5. Disruptions in the function of the efferent arteriole can lead to conditions such as hypertension or reduced kidney function.

Review Questions

• How does the diameter of the efferent arteriole affect glomerular filtration rate (GFR)?
  • The smaller diameter of the efferent arteriole compared to the afferent arteriole increases resistance, which elevates pressure within the glomerulus. This elevated pressure is crucial for effective filtration of blood as it allows more fluid and solutes to be pushed into the Bowman’s capsule. Therefore, changes in the diameter of the efferent arteriole can significantly impact GFR.
• Discuss how hormonal regulation affects the function of the efferent arteriole and its impact on kidney health.
  • Hormonal regulation plays a vital role in controlling the diameter of the efferent arteriole. For example, angiotensin II can cause constriction of this vessel, leading to an increase in GFR during times of low blood volume or pressure. This regulatory mechanism helps maintain kidney function under stress; however, chronic overactivity can contribute to hypertension and damage to renal structures over time.
• Evaluate the importance of both afferent and efferent arterioles in maintaining homeostasis within the renal system.
  • Both afferent and efferent arterioles work together to regulate blood flow and pressure within each nephron, which is essential for maintaining homeostasis. The afferent arteriole controls how much blood enters the glomerulus, while the efferent arteriole manages how much leaves after filtration. This balance is crucial for adjusting GFR based on physiological needs, influencing urine production and electrolyte balance, and ensuring overall kidney health and function.

Related terms

afferent arteriole: The afferent arteriole is a blood vessel that carries blood toward the glomerulus, supplying it with blood rich in waste products for filtration.

glomerulus: The glomerulus is a network of capillaries located at the beginning of each nephron where blood filtration takes place.

peritubular capillaries: These are tiny blood vessels that surround the nephron's tubular structures, facilitating the exchange of substances between blood and renal tubules.