Afferent arteriole, Henle's loop, vasa rectae,efferent arteriole.

Answer

### Step-by-Step Solution:

1. **Understanding the Afferent Arteriole**:
- The afferent arteriole is a blood vessel that carries blood to the glomerulus, which is a network of capillaries located at the beginning of a nephron in the kidney. It is a branch of the renal artery.

2. **Explaining Henle's Loop**:
- Henle's loop, also known as the loop of Henle, is a U-shaped portion of the nephron tubule. It plays a crucial role in the concentration of urine by facilitating the recovery of water and sodium chloride from the filtrate.

3. **Describing Vasa Recta**:
- The vasa recta are straight blood vessels that supply the renal medulla. They are essential for maintaining the osmotic gradient in the kidney, allowing for the concentration of urine. The vasa recta descend into the medulla as straight arterioles and ascend back to the cortex as venules.

4. **Understanding the Efferent Arteriole**:
- The efferent arteriole is the blood vessel that drains blood away from the glomerulus. It carries blood away from the nephron and eventually leads to the peritubular capillaries or vasa recta, depending on the nephron type.

### Summary:
- Afferent arteriole: Brings blood to the glomerulus.
- Henle's loop: U-shaped tubule for water and sodium recovery.
- Vasa recta: Straight blood vessels supplying the renal medulla.
- Efferent arteriole: Drains blood away from the glomerulus.