Q1
Compare and contrast the structure and function of teeth in mammals by:
- describing the structure and function of the different types of teeth in mammals
- explaining the importance of teeth in the overall process of digestion
- comparing and contrasting the structure and function of the teeth of carnivores, omnivores, and herbivores in relation to their role in food digestion.
There are four main types of teeth, incisors, canines, molars and pre-molars. They each have different functions; however, they all have similar structures. Canines are sharp pointed teeth, incisors are chisel-shaped teeth and premolars and molars are flat teeth for grinding. All types of teeth are made up of dentine, enamel and pulp. Enamel is the protective layer around the outside of the tooth, dentine is a softer protective layer and pulp is a soft central part that contains blood vessels and nerves. The purpose of incisors is to cut and tear food. They are commonly used for cutting and snipping grass and plant material. The purpose of canines is for puncturing and tearing food. They are commonly used for killing prey by puncturing their internal organs and for tearing meat. Premolars and molars have a similar function. They are used for grinding food into smaller pieces. Teeth are very important in digestion. This is because they begin the process of physical digestion. Since physical digestion occurs in the mouth, it allows the food to be cut into small pieces so that it can travel down the oesophagus to the stomach where chemical and physical digestion can continue to occur. Herbivores, carnivores and omnivores all have the same types of teeth, they all have incisors, canines, premolars and molars. However, due to the different animals’ diets, they can be of different sizes to allow for optimal function. Since herbivores mainly eat plant material and grass, they have large incisors. This is because they have to eat lots of food to get the required nutrients so as a result need large incisors to cut the grass so that they can digest it. In contrast, since carnivores diet is mainly meat-based they do not need large incisors. This is because they do not need to snip and cut plant material. Omnivores have medium-sized incisors this is because they have a mixed diet meaning they do need to cut and snip some plant material but not as much as herbivores because they eat meat as well. Carnivores diet is meat-based. This means they require large canines in order to catch prey and to puncture the preys internal organs to kill them. They also require large canines to rip the meat off the dead animal. In contrast, since herbivores do not eat meat they do not require large canines. Herbivores have greatly reduced sized canines and sometimes they are missing completely. However, omnivores have incisors as well they are usually smaller than carnivores canines because they do not require them for all food sources since they eat plant material as well. Herbivores, carnivores and omnivores all have pre-molars and molars. Carnivores premolars and molars are sometimes called carnassial teeth. This is because they are sharp and pointed however they still have a larger surface area than canines and incisors. They are used for grinding food. Carnivores and omnivores jaws can only move up and down because the food they eat is easier to be chewed into smaller pieces due to the structure. Omnivores premolars and molars are used to crush and grind the food into smaller pieces and so are herbivore molars. However, due to the tough structure of the plant material herbivores eat the food must be chewed for longer. To increase efficiency, herbivores can move their jaws laterally as well as up and down.
Q2
Discuss how FOUR parts of the digestive system work together to allow digestion to occur effectively, by:
- describing and explaining the function of the different parts of the digestive system
- explaining how the function of each part is important to the overall process of food digestion
- discussing how the parts of the digestive system work together to allow digestion to occur effectively.
The stomach, small intestine, pancreas and liver work together to ensure the digestive system works effectively. Once the food has been ingested by the mouth and some chemical digestion of carbohydrates and some physical digestion has occurred, the ball of food called the bolus travels down the oesophagus to the stomach. The stomach is essential in the digestive system. In the stomach, more physical digestion occurs due to the churning of the stomach. Chemical digestion also occurs. Enzymes that were produced in the pancreas are used in the stomach. In the stomach, pepsin breaks down proteins into polypeptides. The stomach is important because in order for nutrients to be absorbed food has to be broken down both chemically and physically and both of these types of digestion occur in the stomach. After the broken down food now called chyme travels into the small intestine. Since the small intestine has a higher pH than the stomach bile must be added to increase the pH. This allows for enzymes such as lipase which breaks down lipids into glycerol and fatty acid and protease which breaks down polypeptides into amino acids to function. The small intestine is also where the majority of absorption occurs. The villi which line the small intestine increase the surface area allowing for maximum absorption of nutrients. This makes the small intestine extremely important as the nutrients cannot be used if they are not absorbed into the bloodstream where they can travel around the body to the areas which need them. Although food does not travel through the pancreas it is extremely important because it produces many different enzymes. It produces lipase, protease and pepsin enzymes. Enzymes are extremely important because they speed up the process of chemical digestion which allows the nutrients to be absorbed into the bloodstream faster. Additionally, the liver also does not have food travel through it but it is important. The liver is responsible for creating bile. Bile is added at the start of the small intestine to increase the pH this means that the enzymes protease and lipase which have an optimal pH of 7 can work effectively. It also can emulsify large masses of fat allowing the nutrients to be absorbed. These organs all work together to allow for effective digestion the pancreas works with the stomach and small intestine by releasing enzymes which allow chemical digestion in these areas to occur faster meaning the digestive process is more effective. The liver works with the food coming out of the stomach and the small intestine to regulate the pH ensuring that all enzymes can work at their optimal pH. The stomach and small intestine work together to ensure food can be digested and absorbed efficiently so that the body can get the nutrients easily.
Q3
Discuss how the parts of the circulation system work together to allow the products of digestion to be transported around the body, by:
- describing the function of parts of the circulation system involved in transporting the products of digestion around the body
- explaining how the different parts of the circulation system transport the products of digestion around the body
- discussing how parts of the circulation system work together so that it can effectively transport the products of digestion around the body.
The small intestine is where the majority of nutrients are absorbed. It is lined with small finger-like projections called villi which are covered in even smaller microvilli. The villi and microvilli increase the surface area of the small intestine allowing for maximum absorption. In each villus is the lymph capillary this allows for the products absorbed through the villi to easily diffuse into the bloodstream so that they can be transported around the body. From the lymph capillary, the nutrients travel to the hepatic portal vein which takes them to the liver. In the liver simple amino acids are built up into proteins so that they can be used around the body, any excess protein is destroyed as the liver cannot store it. Glucose also travels to the liver and any excess glucose is stored as glycogen in the liver which can be used at a later time. From here the nutrients travel around the bloodstream in the arteries and then they travel in the capillaries which are one cell thick blood vessels so they can easily diffuse into the cells. The waste products in the cells then travel through the veins so they can be excreted. The veins, arteries and capillaries work together to allow effective transportation by a one-way system. The nutrients and oxygen travel through the arteries to the cells and once they get to the cells they travel in capillaries that link the arteries and veins. From here they diffuse into the cells and waste products diffuse out. They waste products then travel through the veins so they can be excreted. By having a one-way system it means the nutrients and waste products are not mixed so they can be efficiently transported to and from cells.