The pigment that is responsible for the color of the iris in the eye is: MCQ with Answer and Explanation

Explanation:
The cardiac conduction system ensures coordinated heartbeats. The sinoatrial (SA) node generates the electrical impulse, acting as the natural pacemaker. The impulse reaches the atrioventricular (AV) node, which delays it slightly to allow the atria to fully contract and empty into the ventricles. The impulse then travels down the Bundle of His to the Purkinje fibers, which rapidly distribute it throughout the ventricular myocardium, causing ventricular contraction. All statements are correct.

Explanation:
Transitional epithelium (urothelium) is stratified, with cells that can change shape from cuboidal to squamous when the bladder distends. It lines the renal pelvis, ureters, bladder, and part of the urethra. Squamous is flat, cuboidal cube-shaped, columnar tall.

Explanation:
Gastrin is a peptide hormone produced by the G cells (gastrin cells) located in the pyloric antrum of the stomach. Its primary function is to stimulate the parietal cells of the gastric glands to secrete hydrochloric acid (HCl) and the chief cells to secrete pepsinogen. This prepares the stomach for the digestion of food. Gastrin also stimulates gastric motility and growth of the gastric mucosa. Secretin and CCK stimulate the pancreas and gall bladder.