Let us first see the structure and function of the kidney briefly before looking at the difference between Bowmans capsule and Malpighian capsule. The kidney is one of the most important organs in the human body and mainly involved in the excretion of metabolic waste products. The main excretory products include water, urea, uric acid, creatinine, and salts of sodium, calcium, magnesium, and potassium. In addition, kidney also helps to maintain the fluid and electrolyte balance of the body, osmotic pressure, retain plasma constituents like glucose, amino acids, etc., and to regulate blood pH. The functional and structural unit of the kidney is nephron. Nephron is made up of mainly two parts; (a) Malpighian capsule, which includes Bowman’s capsule and renal glomerulus and (b) renal tubule that includes; proximal convoluted tubule, Henle’s loop with descending and ascending limbs, distal convoluted tubule, and collecting tubule. The key difference between them is, bowman’s capsule is the cup-shaped end of a renal tubule or nephron enclosing a glomerulus, that performs the first step in the filtration of blood to form urine and combined with the renal glomerulus, it forms the Malpighian capsule. This article discusses the difference between Bowman’s capsule and Malpighian capsule in detail.
What is Bowman’s Capsule?
Bowman’s capsule is a double-walled cup-shaped structure and forms the expanded blind end of the nephron. It is lined by a thin semipermeable squamous epithelium. The cavity of the Bowman’s capsule is about 0.2 mm in diameter and contains the mass of blood capillaries called glomerulus. Bowman’s capsule collects the water and other diffusible solutes from glomerulus through the ultrafiltration.
The labelled parts are 1. Glomerulus, 2. Efferent arteriole, 3. Bowman’s capsule, 4. Proximal convoluted tubule, 5. Cortical collecting duct, 6. Distal convoluted tubule, 7. Loop of Henle, 8. Papillary duct, 9. Peritubular capillaries, 10. Arcuate vein, 11. Arcuate artery, 12. Afferent arteriole, 13. Juxtaglomerular apparatus.
What is Malpighian Capsule?
The Bowman’s capsule and the glomerulus collectively form the Malpighian capsule or renal corpuscle. Glomerulus lies in close contact with the capsule. The blood circulated in the glomerulus is separated from the cavity of Bowman’s capsule by two very thin one cell layer thick membranes; the endothelial layer of blood capillaries and the epithelial layer of Bowman’s capsule. When blood enters to glomerulus through the afferent arteriole, many blood components including water molecules and other solute molecules in the blood plasma are diffused into the Bowman’s capsule. This filtration process of filtration of blood that takes place in the Malpighian capsule is called ultrafiltration.
The renal corpuscle in the cortex (outer layer) of the kidney. At the top, the renal corpuscle containing the glomerulus. The filtered blood exits into the renal tubule, at right. At left, blood flows from the afferent arteriole (red), enters into the renal corpuscle and feeds the glomerulus; blood flows out of the efferent arteriole (blue).
What is the difference between Bowmans Capsule and Malpighian Capsule?
Definition of Bowmans Capsule and Malpighian Capsule
Bowman’s capsule: It is the double walled rounded dilation that ensheathes the urinary tubule and the glomerulus, which has an inner (visceral) layer, formally the capsular epithelium, and an outer (parietal) layer, formally, the glomerular epithelium.
Malpighian capsule: It is the thin fibrous membrane enveloping the spleen and continued over the vessels entering at the hilus.
Characteristics of Bowmans capsule and Malpighian Capsule
Structure
Bowman’s capsule: Bowman’s capsule is a double-walled cup-shaped structure and forms the expanded blind end of the nephron.
Malpighian capsule: The Bowman’s capsule and the glomerulus collectively form the Malpighian capsule.
Function
Bowman’s capsule: Bowman’s capsule collects the water and other diffusible solutes filtered from glomerulus and pass the glomerular filter into proximal convoluted tubule.
Malpighian capsule: The ultrafiltration takes place in the Malpighian capsule.
Image Courtesy:
“Nephron illustration” by Burton Radons – Own work. (CC0) via Commons