the nervous system
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The polar has a nervous system that consists of its five senses that help them respond to external stimuli. They include:
Tactile
- Polar bears have been seen to touch with their nose, mouth, claws and paws to move around objects or food.
- Mother polar bears are often seen touching and grooming their young.
- They have broad feet with hairy soles which help them keep warm and grip the ice.
- Their broad feet also help them swim because, like paddles, they can push away more water.
- Polar bears use their tongues to taste and often prefer different foods. Yet, researchers do not know how acute their sense of taste is.
- Although not a lot of information is known about polar bears’ sense of hearing, they seem to have around the same frequencies of humans or slightly better.
- They have small and round ears which helps the preserve heat due to how there is less available space for the heat to escape.
- Polar bears can communicate to each other through sound such as growling and or chomping of teeth.
- A polar bear's sense of smell is very strong
- They can supposedly smell a seal up to 20 miles away.
- Polar bears have a nictitating membrane which protects their eyes from ultraviolet light.
- They also have good eyesight in both the light and the dark.
- They can hunt at night or in the day.
- Their eyes are dark brown, are set close together, and are face forward.
Details of the Nervous System
Within the nervous system there is the peripheral nervous system and the central nervous system. When there is an external stimuli a signal is sent throughout the body to a certain destination first through the peripheral nervous system then to the central nervous system which consists of the brain and spine. After the signal is processed in the brain, then a reaction will occur. For instance, if a polar bear sees a human coming to attack it, then it will move out of the way and start to run. The response to this situation is made possible due to the nervous system. At the beginning, the polar bear uses its eyes to sense that there is a certain danger involving the human. This signal is then sent through the peripheral nervous system using afferent neurons, or nerve cells that transport information to the central nervous system, so it can be understood by the brain. Once the signal of a predator reaches the brain, a response will be made made by the brain and by using efferent neurons, or nerve cells that transport information back to the peripheral nervous system, a signal will be sent to muscle cells and other nerves to run away. Overall, polar bears, and all other mammals, use the nervous system to react to external stimuli.
https://docs.google.com/presentation/d/1DEO_xSSBfhL075QncWefFm2KU5Fk2uZwUmPiz-jyciw/edit#slide=id.p27
Different parts of the nervous system
However there are many different systems that make up the central nervous system as a whole. For example, there is the:
Motor System - The motor system brings signals to the skeletal muscle and can be voluntary or involuntary, meaning a person can control it or it can be completely automatic.
Autonomic System - The autonomic nervous system regulates smooth and cardiac muscles and is most of the time involuntary.
Autonomic System - The autonomic nervous system regulates smooth and cardiac muscles and is most of the time involuntary.
- Sympathetic Division - A branch of the autonomic system that regulates the fight or flight method, or whether an organism should stay and try and solve a conflict or run away from it, and this division also helps to cope with an emergency situation.
- Parasympathetic Division - A branch of the autonomic system that calms an organism down after a certain conflict.
- Enteric Division - A branch of the autonomic system that focuses on the digestive system. Most likely during a dangerous conflict, this system shuts off in order to keep all other systems functioning better and correctly.
The endocrine system
The endocrine system is a system that deals with hormones and is much slower then the nervous system. It also transports those hormones to all areas of the body or to a certain destination through the blood stream. To maintain homeostasis, or balance in the body, the endocrine system is great at making gradual changes to the body. For instance, using the previous example, if a polar bear sees a human and needs to run quick, the adrenal gland will excrete epinephrine, or commonly known as adrenaline, so that the body can can produce more energy. The surplus of epinephrine will cause the body to slow down the production of insulin and speed up the production of glucagon in the pancreas. Also, epinephrine causes increased heart rate and dilated airways. Ultimately, the creation of epinephrine helps mammals in the fight or flight response, to allow them to run faster or fight harder. Other endocrine glands are the hypothalamus, pituitary gland, pancreas, and the ovaries in females and the testes in males. Every gland produces different hormones, but they all are made in order to keep the organism at homeostasis.
Other Internal Stimuli
Body Temperature - A polar bear regulates its body system by using negative feedback since it is an endotherm. When they get too hot their blood vessels will dilate and they will begin to pant. This will help them to cool down. Especially in animals in zoos located in warmer climates. Polar bears are not used to the warmth, so in order to keep them alive they need to make the environment cool enough for them to live in. However, to keep themselves warm, polar bears have very thick fat and fur. Since their main food source is fat from seal, the tend to grow warm outer coats to keep warm. Also when too hot, their blood vessels will constrict.
Waste Filtration and Elimination - Polar bears have the same type of digestive system as all other mammals. Once they eat their food, usually seal, using their teeth, the chewed up bits will travel down the esophagus and into the stomach where it will broken down by stomach acid into a liquid. This liquid travels through the small intestine, and into the blood stream, as well as through the large intestine where water will be used to help exit the excrement through the anus.
Water Balance - The majority of the way that polar bears get their water intake is by eating fats. The chemical process that breaks down these fats produces a large amount of water since they have a high fat low carbohydrate diet. Also, since the polar bears live an area that is always cold, they do not sweat due to the temperature and their large coat. This always them to maintain a balance in water.
Negative and Positive Feedback -- Polar bears' endocrine system works on either a negative or positive feedback mechanism. If the response that is triggered by the polar bear stops the stimulus, then it is working on a negative feedback loop. An example of this is the monitoring of body temperature. If the response triggers the stimulus even more, it is working on a positive feedback loop. A good example of a positive feedback loop in polar bears is the secretion of milk from mothers to their cubs.
Waste Filtration and Elimination - Polar bears have the same type of digestive system as all other mammals. Once they eat their food, usually seal, using their teeth, the chewed up bits will travel down the esophagus and into the stomach where it will broken down by stomach acid into a liquid. This liquid travels through the small intestine, and into the blood stream, as well as through the large intestine where water will be used to help exit the excrement through the anus.
Water Balance - The majority of the way that polar bears get their water intake is by eating fats. The chemical process that breaks down these fats produces a large amount of water since they have a high fat low carbohydrate diet. Also, since the polar bears live an area that is always cold, they do not sweat due to the temperature and their large coat. This always them to maintain a balance in water.
Negative and Positive Feedback -- Polar bears' endocrine system works on either a negative or positive feedback mechanism. If the response that is triggered by the polar bear stops the stimulus, then it is working on a negative feedback loop. An example of this is the monitoring of body temperature. If the response triggers the stimulus even more, it is working on a positive feedback loop. A good example of a positive feedback loop in polar bears is the secretion of milk from mothers to their cubs.