digestive tract | Vet In Training

Cat with yellowing eyes (Photo credit, Thinkstock)

Cat Gallbladder

This week I’m going to tell you about the gallbladder. The feline gallbladder to be precise. The gallbladder rests in the abdomen, firmly affixed to the liver and serving as a storage receptacle for bile, a fluid that is essential for digesting food in the stomach and intestines. The bile duct transports bile from the liver into the gallbladder and into the small intestine, and the liver functions in the secretion of the bile. Inflammation of the gallbladder is often associated with obstruction and/or inflammation of the common bile duct and/or the liver/bile system, and is sometimes associated with gallstones. Severe cases of inflammation can result in rupture of the gallbladder and subsequent severe inflammation of the bile duct (bile peritonitis), necessitating combined surgical and medical treatments. Some of the symptoms that can be indicative of an inflamed gallbladder or bile duct are sudden loss of appetite, lethargy, vomiting, and abdominal pain. Mild to moderate jaundice with concurrent fever is commonly associated with conditions of the bile duct. Look for yellow eyes and yellowing of the gums. Shock due to infection and reduction in blood volume can also occur. Signs of shock include shallow breathing, hypothermia, pale or gray gums, and a weak but rapid pulse. Inflammation and adhesions involving the gallbladder and adjacent tissues can lead to swelled tissue; a palpable mass of tissue will be felt in the upper right abdomen, especially in smaller sized cats. The causes for an inflamed gallbladder or bile duct can result from one or more conditions that will lead up to it. Muscles in the gall bladder may be malfunctioning, which can lead to impaired bile flow in the cystic duct or gall bladder, irritating the walls of the gallbladder. Or the blood supply to the gallbladder wall is being restricted, in which case the cause for the restriction must be isolated and treated to improve the blood flow. Irritants in the bile can cause the bile duct to be overly sensitive and reactive; a backward flow of pancreatic enzymes may trigger and intensify inflammation. Previous abdominal surgery, or trauma to the abdomen, can directly lead to internal sensitivity, affecting one or more of the internal organs, including the liver and gallbladder. Gallbladders are essential in carnivores, but not so much in herbivores as the horse doesn’t even have one. All of the components of the digestive system work in tandem, and if one fails to function properly, the result is that most of the body will suffer ill effects.

To see what a gallbladder looks like, click here to watch my video.

Chicken stomach (photo credit nutrenaworld.com)

Chicken Stomachs

This week we’ll look at the chicken stomach. Bird stomachs are different from mammal stomachs in many ways. Today we will be looking at the Crop, the Proventriculus, and the Gizzard. The crop is an out-pocketing of the esophagus and is located just outside the body cavity in the neck region. Any swallowed food and water is stored in the crop until it is time to pass it on to the rest of the digestive tract. When the crop is empty, or nearly empty, it sends hunger signals to the brain so that the chicken will eat more. Although salivary glands of the mouth secrete the digestive enzyme amylase, very little digestion actually takes place in the crop, it is simply a temporary storage pouch. The proventriculus (also known as the ‘true stomach’) is the glandular stomach where digestion begins. As with human stomachs, hydrochloric acid and digestive enzymes (like pepsin) are added to the food here. At this point however, the food has not yet been ground up. The term ‘proventriculus’ is used since it comes before the ‘ventriculus’ or gizzard, with ‘pro’ being the Latin term meaning before. And finally, the gizzard. The gizzard, or ventriculus, is a part of the digestive tract unique to birds. It is often referred to as the ‘mechanical stomach’. It is made up of two sets of strong muscles which act as the bird’s teeth. Consumed food and the digestive juices from the salivary glands and the proventriculus pass into the gizzard for grinding, mixing, and mashing, which is aided by the small stones or grit the bird consumes. These stones remain in the gizzard until they become ground into pieces small enough to pass through to the rest of the digestive tract. The stones/grit are weakened by the acidic environment created in the proventriculus and then are ground into tiny pieces by the strong muscles of the gizzard. This is how chickens can eat a lot of hard seeds and not get digestive issues like humans. Ultimately, Chicken stomachs are designed to ingest the bugs and seeds which chickens need to survive. If any part of the stomach did not work correctly, the chicken might die. Which just goes to show how intricate the whole system is.