Animal Physiology.docx

21.Animal Physiology   Ingestion is the First stage of the digestive process. The intake of food into the body takes place in the mouth. The Physical (mechanical) process threw teeth & tongue.    Chemical process is throwing saliva (enzymes) which help break down food.     Diagram of the tooth  ...

21.Animal Physiology   Ingestion is the First stage of the digestive process. The intake of food into the body takes place in the mouth. The Physical (mechanical) process threw teeth & tongue.    Chemical process is throwing saliva (enzymes) which help break down food.     Diagram of the tooth      Dental formulas of animals  Incisors are used for biting.   Canines are used for tearing.   Premolars are used for grinding.   Movers are used for Cushing.     Chemical digestion in the mouth  Monogastric animals (humans, pigs) secrete an enzyme called amylase breaks down starch (substrate) into maltose (product).  Saliva has a secondary function to act as a lubricant to soften food for swallowing. Food is passed as a bolus into the oesophagus where it travels to the stomach by a process called peristalsis it has an Involuntary muscular contractions which have a wave like motion.     Digestion in the ruminant animal  Cattle & sheep are ruminant animals.   They have a four-chamber stomach The rumen, reticulum, omasum & abomasum.   The four chambers are important to help cows digest the tough material cellulose found in grass. Grass enters the first chamber where partial digestion occurs.   The plant material, now known as ‘cud ’, is regurgitated from the second chamber, and chewed again before being swallowed and passed into the other two chambers where it is fully digested.        The rumen contains microorganisms (bacteria & protozoans) to help digest cellulose It has a pH of 7.  Carbon dioxide and methane gas are also produced in rumen and forces the gases out when this doesn’t occur it causes bloat see image below        This mainly Occurs in cattle that rumen ph. falls below a ph. of 5 due to been put out on early grass containing white clover. White clover causes a foam which traps the gases.  Gases build and the left side of abdomen becomes swollen.   The Cure for bloat is Antacid solution or a vet can create an incision in the abdomen and insert a troika and cannula allowing the gas to escape.  Bacteria and microbes build up due to acidic environment.    Symbiosis  Is when Two organisms living in close to one another where at least one of them benefits.  Example: bacteria in rumen feed off cellulose while providing cow with glucose for energy as well as vitamins.    The reticulum Second chamber in ruminant. It Helps to regurgitate partially digested food ‘cud’ from rumen back to mouth for further chewing, i.e., ‘chewing the cud’.    The omasum is the Third chamber in ruminant. The Regurgitated food is passed from mouth to omasum. It has many layers of tissue and squeezes the food, reabsorbing water and liquid from it.     The abomasum Fourth chamber in ruminant and is known as the real stomach. It breaks down proteins and aid the final stage of digestion.    The small intestine is Composed of duodenum and ileum. Food moves through the small intestine by the process peristalsis.   The first section is called the duodenum. This connects the stomach to ileum in the ileum is where majority of reabsorption of nutrients occurs. Bile and pancreatic juices are secreted into the small intestine.    The large intestine Consists of the caecum and the colon. Primary function is the reabsorption of water and to pass waste to the anus.     Digestion in young ruminant such as calves or lambs do not have a fully functioning ruminant. milk is brought straight to the abomasum for digestion. As they begin to feed, microorganisms begin to develop in the rumen, it takes six weeks for rumen and reticulum to fully developed.          The monogastric animal such as pigs and humans. Have only one stomach. They have No rumen and cannot digest cellulose.    The liver in a monogastric is a vital organ that carries out a range of functions it’s stores Glucoses as glycogen here. Glycogen can be broken down into glucose when energy levels are low, along with a range of vitamins and minerals. It Breaks down toxic substances such as Ammonia is converted to urea in the liver. Ammonia is produced when excess amino acids.  Red blood cells are recycled in the liver and used as pigments in bile production. It also regulates Temperature Heat is produced by the liver and warms the blood as it passes through the organ.       The digestive system of a chicken  Chickens do not have teeth. They have a beak which is adapted for different types of feeding, depending on species. Food is passed down from oesophagus to stomach. Chickens swallow grit which ends up in the gizzard. When food enters the gizzard, the grit grinds down the food mechanically. Chickens also have a crop which allows them to store food for later consumption.  The stomach is divided into two parts: the proventriculus and the gizzard. Chickens do not contain a separate urinary tract, so urine and faeces are passed out together.                     

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