Skeletal System
Overview
The skeletal system is comprised of bones, cartilage, ligaments, and tendons. This system is vital to the survival of many organisms including bears and humans. The skeleton helps provide structural support, allows movement to occur, produces red and white blood cells, stores minerals, and helps protect internal organs. The most important part of the skeletal system are the bones which are comprised of the periosteum, haversian canals, and bone marrow(produces blood cells). Other parts of the skeletal system are the cartilage which allows for flexibility, ligaments which connect bone to bone, and tendons which connect bone to muscle. The skeletal system plays an important roles in maintaining homeostasis in organisms.
Comparison
Most of the main features of the skeletal system are shared by both bears and humans. This includes the basic framework of the skull, the rib cage, the spinal cord, the arms and legs, and the tail bone. But since bears have evolved to suit their physical environments some parts of their skeletal system are unique and are very effective for the biomes in which they live in. An example of this is the elongated and wide skull shape which accommodates a very wide jawbone that allows for heavy jaw muscles. Another skeletal feature that black bears possess is the tail bone but unlike in humans these black bears have slightly longer tail bones which are 4 inches long.
Muscular System
Overview
The muscular system is comprised of three types of muscular tissue which are skeletal tissue, cardiac tissue, and smooth tissue. The skeletal tissue attach to bones through tendons and pulls on bones like levers allowing movement. The cardiac tissue is the tissue that the heart is mostly made of, it is the strongest of the three muscular tissues and is packed with mitochondria. Finally, the smooth tissue makes up most of the organs, and allows the organ to function. The muscular system is very essential for organisms to survive.
ComparisonMost of the main features of the muscular system are shared by both bears and humans. This includes the cardiac tissue, the skeletal tissue, and the smooth tissue. As in humans the cardiac tissue is found in the heart of the bear, the smooth tissue is found in the inner linings of organs, and the skeletal tissue is attached to the skeleton and help the bear move. But in bears, the skeletal tissue is found further away from the bone than in a human. This allows the bear to have very strong movements but this structure also makes the bear slower, while in humans the skeletal tissue is found near the bone allowing for weaker and faster movements.
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Nervous System
Overview
The nervous system is made up of the CNS(Central Nervous System) which is comprised of the brain and spinal cord and the PNS(Peripheral Nervous System) which is comprised of the motor and sensory neurons. These two systems work together to help form the complete nervous system. The nervous system works off electrical impulses and specialized cells called neurons. When an organism comes into contact with a stimuli such as hot water, electrical impulses travel to the brain which then get interpreted and sent back which then causes an action. The nervous system is the most important system along with the endocrine system to helping maintain homeostasis in an organism.
Comparison
Most of the main features of the nervous system are shared by both bears and humans. This includes the basic framework of the CNS(Central Nervous System) and the PNS(Peripheral Nervous System). These two systems work together to form the nervous system. But in bears the nervous system is more tuned to the senses than in humans. An average bear’s smell is a 100 times better than a human's, their ears are 2 times better at hearing sounds than ours and they can hear a wider range of frequencies,and a bear’s vision is just as good or even slightly better than ours. This allows the bear to better hunt and capture prey.
RESPIRATORY System
Overview
The respiratory system is mainly comprised of the lungs, trachea, diaphragm, bronchi, aveoli, and the nose. The respiratory system is vital to survival of large organisms like the bear and the human because it allows for aerobic cellular respiration. When an organism breaths the air goes down the trachea till it reaches the lungs where gas exchange occurs in the aveoli then the carbon dioxide gets expelled when you exhale. The respiratory system is most closely tied in with the circulatory system but it also interacts with other system to help provide homeostasis.
Comparison
Most of the main features of the respiratory system are shared by both bears and humans. This includes the basic framework of the lungs, trachea, and diaphragm. The respiratory system works through the exchange of gases in the lungs.The organism breaths allowing oxygen to travel down the trachea reaching the lung where the exchange of gasses occur. But in bears the lungs are much larger than humans allowing bears to stay longer without a breath. This adaptation is used to help the bear catch it’s prey in the water. Another adaptation that bears have is that they can close their nasal cavity so when they swim in water, the water won’t go down the bear’s nose.
Circulatory System
Overview
The circulatory system is comprised of the heart, blood, veins, capillaries, and arteries. The circulatory system helps deliver oxygen, nutrients, and hormones to cells, it helps fight infections, it removes cellular waste, and it helps regulate body temperature. The circulatory system is essential for large organisms so all parts of the body can receive nutrients. The circulatory system is most closely tied in with the respiratory system but it also interacts with various system to help provide homeostasis to the organism.
Comparison
Most of the main features of the circulatory system are shared by both bears and humans. This includes the basic framework of the heart, arteries, veins, and capillaries. Both in bears and humans the circulatory system is vital to the survival of the organism, it helps move nutrients, oxygen, waste, and white blood cells around the organism. But in bears the veins have more valves than in humans because a bear doesn’t stand upright making the risk of blood going the wrong direction higher. Bears also have red blood cells that can hold more oxygen than human blood cells. This adaptation is used to help the bear stay longer underwater allowing them to hunt prey more effectively. The bear also can dilate their blood vessels more than human which allows them to maintain heat in colder frigid waters.
Digestive System
Overview
The digestive system is comprised of the mouth, esophagus, stomach, liver, small intestine, large intestine, and the rectum. The digestive system helps convert food into substances that cell can use to make ATP, it helps absorb food, and it also eliminates waste through the rectum. The digestive system is very important to the survival of the organism because it helps digest polymers to monomers which then cells can use to help function. The digestive system is also very diverse among different organisms because the digestive system is mostly going to be adapted to what the diet of the organism is.
Comparison
Most of the main features of the digestive system are shared by both bears and humans. This includes the basic framework of esophagus, stomach, small intestine, large intestine, liver and rectum. But in bears most of the fermentation takes place in the colon of the bear, bears also have a long gut for digesting grasses but don't digest starches that well. The bear's digestive tract is different than a carnivores because they have a longer small intestine but it is also different than a herbivore because the digestive tract lacks features of a true herbivore. These adaptations are best suited to the diet that bears eat, they eat various small fruits and shrubs but also eat other animals.
Excretory System
Overview
The excretory system is comprised of the kidneys, the ureter, urinary bladder, and urethra. The excretory system helps eliminate waste, maintain blood Ph, and regulate blood volume. The elimination happens when the body excretes urine(nitrogen-containing metabolic waste). Similar to the other body systems, the excretory system interacts with other systems and helps maintain homeostasis. The excretory system only deals with the bodily fluids, not solid wastes that are taken care of in the digestive system.
Comparison
Most of the main features of the excretory system are shared by both bears and humans. This includes the basic framework of the kidney, ureter, urethra, and urinary bladder. They both have the basic function of taking wastes out of the body that would damage the body if not taken care of properly. They both attempt to maintain chemical balance particularly balance of water, salts, and nutrients. The similar structures between both would include the ureters, kidneys, bladder, and the urethra. The bears excretory system is very similar to ours and is not very different.