Mouth and oral structures
Lipase - digests fat. Your food may spend as long as 4 hours in the small intestine and will become a very thin, watery mixture. For example, trypsin is secreted by pancreas in the form of trypsinogen , which is activated in the duodenum by enterokinase to form trypsin. For specific medical advice, diagnoses, and treatment, consult your doctor. After some time typically 1—2 hours in humans, 4—6 hours in dogs, 3—4 hours in house cats , [ citation needed ] the resulting thick liquid is called chyme. Three organs play a pivotal role in helping the stomach and small intestine digest food:. Well, here's a hint:
The Digestive and Endocrine System Game
Stool, or waste left over from the digestive process, is passed through the colon by means of peristalsis contractions , first in a liquid state and ultimately in solid form as the water is removed from the stool. A stool is stored in the sigmoid colon until a "mass movement" empties it into the rectum once or twice a day. It normally takes about 36 hours for stool to get through the colon. The stool itself is mostly food debris and bacteria. These bacteria perform several useful functions, such as synthesizing various vitamins , processing waste products and food particles, and protecting against harmful bacteria.
When the descending colon becomes full of stool, or feces, it empties its contents into the rectum to begin the process of elimination. The rectum Latin for "straight" is an 8-inch chamber that connects the colon to the anus. It is the rectum's job to receive stool from the colon, to let you know there is stool to be evacuated, and to hold the stool until evacuation happens.
When anything gas or stool comes into the rectum, sensors send a message to the brain. The brain then decides if the rectal contents can be released or not. If they can, the sphincters muscles relax and the rectum contracts, expelling its contents. If the contents cannot be expelled, the sphincters contract and the rectum accommodates, so that the sensation temporarily goes away. The anus is the last part of the digestive tract.
It consists of the pelvic floor muscles and the two anal sphincters internal and external muscles. The lining of the upper anus is specialized to detect rectal contents.
It lets us know whether the contents are liquid, gas, or solid. The pelvic floor muscle creates an angle between the rectum and the anus that stops stool from coming out when it is not supposed to. The anal sphincters provide fine control of stool. The internal sphincter keeps us from going to the bathroom when we are asleep, or otherwise unaware of the presence of stool. Hope you have fun with this. CQ Here's an activity I've used with grade. Teacher Demonstration Messy but memorable: Take some panty hose and cut off one leg, leaving an opening at each end.
Cook some instant oatmeal. I usually cook 3 - 4 cups. Set aside until demonstration. Pack the oatmeat into one end and with the students watching, squeeze the oatmeal from one end to the other end. The porous hose will allow nutrients LOL to escape and by the time you've worked the oatmeal out the other end Sound effects not in lesson plan: The students watch anxiously as you do the demonstration, laughing, oohing, aahing, until that "final moment" when it passes all the way through.
Be prepared for the "Plop! View Item words Zip loc stomach simulator Posted by: The bag is like the stomach - a muscle that squeezes the food.
First have them pour a little orange juice or coke into the bag to act as the "digestive juices. Extracellular digestion takes place within this central cavity, which is lined with the gastrodermis, the internal layer of epithelium. This cavity has only one opening to the outside that functions as both a mouth and an anus: In a plant such as the Venus Flytrap that can make its own food through photosynthesis, it does not eat and digest its prey for the traditional objectives of harvesting energy and carbon, but mines prey primarily for essential nutrients nitrogen and phosphorus in particular that are in short supply in its boggy, acidic habitat.
A phagosome is a vacuole formed around a particle absorbed by phagocytosis. The vacuole is formed by the fusion of the cell membrane around the particle.
A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested. Phagosomes fuse with lysosomes in their maturation process, forming phagolysosomes. In humans, Entamoeba histolytica can phagocytose red blood cells. To aid in the digestion of their food animals evolved organs such as beaks, tongues , teeth, a crop, gizzard, and others.
Birds have bony beaks that are specialised according to the bird's ecological niche. For example, macaws primarily eat seeds, nuts, and fruit, using their impressive beaks to open even the toughest seed. First they scratch a thin line with the sharp point of the beak, then they shear the seed open with the sides of the beak.
The mouth of the squid is equipped with a sharp horny beak mainly made of cross-linked proteins. It is used to kill and tear prey into manageable pieces.
The beak is very robust, but does not contain any minerals, unlike the teeth and jaws of many other organisms, including marine species. The tongue is skeletal muscle on the floor of the mouth that manipulates food for chewing mastication and swallowing deglutition. It is sensitive and kept moist by saliva. The underside of the tongue is covered with a smooth mucous membrane. The tongue also has a touch sense for locating and positioning food particles that require further chewing.
The tongue is utilized to roll food particles into a bolus before being transported down the esophagus through peristalsis. The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlain by a plexus of veins. This is an ideal location for introducing certain medications to the body.
The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract. Teeth singular tooth are small whitish structures found in the jaws or mouths of many vertebrates that are used to tear, scrape, milk and chew food.
Teeth are not made of bone, but rather of tissues of varying density and hardness, such as enamel, dentine and cementum. Human teeth have a blood and nerve supply which enables proprioception. This is the ability of sensation when chewing, for example if we were to bite into something too hard for our teeth, such as a chipped plate mixed in food, our teeth send a message to our brain and we realise that it cannot be chewed, so we stop trying.
The shapes, sizes and numbers of types of animals' teeth are related to their diets. For example, herbivores have a number of molars which are used to grind plant matter, which is difficult to digest. Carnivores have canine teeth which are used to kill and tear meat.
A crop , or croup, is a thin-walled expanded portion of the alimentary tract used for the storage of food prior to digestion. In some birds it is an expanded, muscular pouch near the gullet or throat. In adult doves and pigeons, the crop can produce crop milk to feed newly hatched birds. Certain insects may have a crop or enlarged esophagus. Herbivores have evolved cecums or an abomasum in the case of ruminants. Ruminants have a fore-stomach with four chambers. These are the rumen , reticulum , omasum , and abomasum.
In the first two chambers, the rumen and the reticulum, the food is mixed with saliva and separates into layers of solid and liquid material.
Solids clump together to form the cud or bolus. The cud is then regurgitated, chewed slowly to completely mix it with saliva and to break down the particle size. Fibre, especially cellulose and hemi-cellulose , is primarily broken down into the volatile fatty acids , acetic acid , propionic acid and butyric acid in these chambers the reticulo-rumen by microbes: In the omasum, water and many of the inorganic mineral elements are absorbed into the blood stream.
The abomasum is the fourth and final stomach compartment in ruminants. It is a close equivalent of a monogastric stomach e. It serves primarily as a site for acid hydrolysis of microbial and dietary protein, preparing these protein sources for further digestion and absorption in the small intestine. Digesta is finally moved into the small intestine, where the digestion and absorption of nutrients occurs. Microbes produced in the reticulo-rumen are also digested in the small intestine.
Regurgitation has been mentioned above under abomasum and crop, referring to crop milk, a secretion from the lining of the crop of pigeons and doves with which the parents feed their young by regurgitation. Many sharks have the ability to turn their stomachs inside out and evert it out of their mouths in order to get rid of unwanted contents perhaps developed as a way to reduce exposure to toxins. Other animals, such as rabbits and rodents , practise coprophagia behaviours — eating specialised faeces in order to re-digest food, especially in the case of roughage.
Capybara, rabbits, hamsters and other related species do not have a complex digestive system as do, for example, ruminants.
Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft faecal pellets of partially digested food are excreted and generally consumed immediately. They also produce normal droppings, which are not eaten. Young elephants, pandas, koalas, and hippos eat the faeces of their mother, probably to obtain the bacteria required to properly digest vegetation.
When they are born, their intestines do not contain these bacteria they are completely sterile. Without them, they would be unable to get any nutritional value from many plant components. An earthworm 's digestive system consists of a mouth , pharynx , esophagus , crop , gizzard , and intestine. The mouth is surrounded by strong lips, which act like a hand to grab pieces of dead grass, leaves, and weeds, with bits of soil to help chew.
The lips break the food down into smaller pieces. In the pharynx, the food is lubricated by mucus secretions for easier passage.
The esophagus adds calcium carbonate to neutralize the acids formed by food matter decay. Temporary storage occurs in the crop where food and calcium carbonate are mixed. The powerful muscles of the gizzard churn and mix the mass of food and dirt. When the churning is complete, the glands in the walls of the gizzard add enzymes to the thick paste, which helps chemically breakdown the organic matter.
By peristalsis , the mixture is sent to the intestine where friendly bacteria continue chemical breakdown. This releases carbohydrates, protein, fat, and various vitamins and minerals for absorption into the body. In most vertebrates , digestion is a multistage process in the digestive system, starting from ingestion of raw materials, most often other organisms. Ingestion usually involves some type of mechanical and chemical processing. Digestion is separated into four steps:.
Underlying the process is muscle movement throughout the system through swallowing and peristalsis. Each step in digestion requires energy, and thus imposes an "overhead charge" on the energy made available from absorbed substances. Differences in that overhead cost are important influences on lifestyle, behavior, and even physical structures.
Examples may be seen in humans, who differ considerably from other hominids lack of hair, smaller jaws and musculature, different dentition, length of intestines, cooking, etc.