The main difference between glomerular capillaries and peritubular capillaries is that glomerular capillaries originate from afferent arteriole, whereas peritubular capillaries originate from efferent arterioles.
Glomerular and peritubular capillaries are two capillary types that occur in the kidney.
Key Areas Covered
1. What are Glomerular Capillaries
– Definition, Structure, Function
2. What are Peritubular Capillaries
– Definition, Structure, Function
3. Similarities Between Glomerular Capillaries and Peritubular Capillaries
– Outline of Common Features
4. Difference Between Glomerular Capillaries and Peritubular Capillaries
– Comparison of Key Differences
Key Terms
Glomerular Capillaries, Peritubular Capillaries
What are Glomerular Capillaries
Glomerular capillaries are tiny blood vessels originating from the kidney’s afferent arteries. They form the glomerulus, the main filtering unit of the kidney. Also, they occur in an enclosed sac called Bowman’s capsule. It occurs at the beginning of the nephron. The afferent arteriole provides the blood supply to the glomerulus. Therefore, the blood from the afferent artery circulates inside the glomerular capillaries. It leaves the glomerulus into the efferent artery. However, the main function of the glomerular capillaries is ultrafiltration, the filtration of blood into urine.
Figure 1: Glomerular Capillaries
Furthermore, the three types of cells in the glomerulus include endothelial cells, smooth muscle cells, and epithelial cells such as parietal cells and podocytes. Endothelial cells surround the glomerular capillaries allowing the rapid filtration of blood. Smooth muscle cells affect the glomerular filtration rate and regulate vascular resistance. Also, parietal cells form the space of Bowman’s capsule. Additionally, the foot processes of the podocytes surround the glomerular capillaries.
What are Peritubular Capillaries
Peritubular capillaries are tiny blood vessels originating from the kidney’s efferent artery. They surround the nephron’s cortical parts, allowing the reabsorption and secretion between the inner lumen of the nephron and the blood. However, the vasa recta surround the medullary parts of the nephron, such as the loop of Henle. Importantly, four-fifth of the blood plasma after the ultrafiltration comes to the peritubular capillaries. Active transport, transcytosis, and secondary active transport are the methods of resorption of ions and minerals from the filtrate into the peritubular capillaries. Other ions that need to be removed from the blood are secreted into the filtrate.
Figure 2: Peritubular capillaries
Moreover, peritubular capillaries reabsorb glucose and amino acids, secreting ions into the filtrate. Other methods that help reabsorption and secretion of components between the filtrate and blood are osmosis and hydrostatic pressure. Due to the loss of water, the colloidal osmotic pressure of the blood increases. It uptakes water from the filtrate when in the peritubular capillaries.
Similarities Between Glomerular Capillaries and Peritubular Capillaries
- Glomerular and peritubular capillaries are two capillary types that occur in the kidney.
- They have different functions in the kidney.
Difference Between Glomerular Capillaries and Peritubular Capillaries
Definition
Glomerular capillaries refer to a specialized bundle of capillaries that are uniquely situated between two resistance vessels, afferent and efferent vessels. In contrast, peritubular capillaries refer to tiny blood vessels in the kidney that deliver wastes to be secreted into the urine.
Origination
Glomerular capillaries originate from the afferent arteries, while peritubular capillaries originate from the efferent arteries.
Occurrence
Glomerular capillaries occur in the glomerulus, while peritubular capillaries surround the cortical parts of the proximal and distal tubules.
Function
Glomerular capillaries filter blood into urine, while peritubular capillaries allow resorption and secretion in the nephron.
Conclusion
In brief, glomerular and peritubular capillaries are two capillary types that occur in the kidney. Glomerular capillaries originate in the glomerulus and originate from the afferent artery. Their function is to filter blood into the urine. In comparison, peritubular capillaries occur surrounding the nephron in the cortex. Also, they originate from the efferent artery. Their function is to allow resorption and secretion of the nephron. Therefore, the main difference between glomerular and peritubular capillaries is their origin, occurrence, and function.
References:
- MD, R. G. (2023, January 25). Glomerulus. Kenhub. https://www.kenhub.com/en/library/anatomy/glomerulus
- (n.d.-g). Peritubular capillaries: Function, location, and health conditions. WebMD. https://www.webmd.com/a-to-z-guides/peritubular-capillaries-what-to-know
Image Courtesy:
- “Physiology of Nephron” By Madhero88 – Own work (CC-BY 3.0) via Commons Wikimedia
- “Figure 41 03 03” By CNX OpenStax – Own Work (CC-BY 4.0) via Commons Wikimedia
Leave a Reply