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Comparing Humans and Crocodiles
Transcript of Comparing Humans and Crocodiles
Each nephron contains a tiny blood vessel known as a glomerulus and a tiny urine collecting tube called a tubule The glomerulus acts as a filtering unit, passing wastes though to the tubule and keeping normal proteins and cells in the bloodstream Water Balance The kidneys also maintain the water balance of the body. they do this in the bowman's capsules. When filtration occurs, the water in the bloodstream becomes part of the filtrate. Then, when reabsorption occurs, the filtered substances leave through the renal tube, and the water follows due to osmosis. When you drink water, the kidneys decrease water reabsorption, causing less water to be returned by the kidneys and more to be sent to the urinary bladder. If not for this process, your cells would swell and burst from the effects of osmosis If you digest more salt, the kidneys cause less salt to be reabsorbed into the bloodstream, and the excess salt in excreted as urine Reproduction Reproduction begins in humans with puberty, a period of rapid growth and sexual maturity, along with the production of testosterone in males and estrogen in females. In males, sperm (the male gamete) is produced. The consist of a head containing a nucleus (with the information to help create a offspring) and a mitochondrial powered tail allowing it to swim to the female gamete The female gamete is known as an egg and is produced in the ovaries. Once roughly every 28 days, a eg is released from the ovaries down the fallopian tubes. During sexual reproduction, sperm are released into the woman's vagina, and swim up the fallopian tubes to hopefully meet an egg cell. With millions of sperm cells released, their is a good chance one will find the egg cell. Once a sperm finds an egg cell, the nuclei merge to become one cell This cell finds its way to the uterus, where the fetus begins to develop by mitosis. Over time, the embryo forms, fueled by nutrients taken in by the mother After the 9 month gestation period, the baby is ready to be born. Muscles in the uterus wall are stimulated by hormonal release. Contractions occur known as labor and the amniotic sac breaks, and contractions force the child out of the vagina. From there, the child develops on its own Transport Crocodiles have a four chambered heart simliar to humans and birds, with two atria and two ventricles, however, they can completely shut off a ventricle to save oxygen and allow them to dive for longer periods of time The two ventricles in a crocodile's heart are completely separated, allowing for different pressures for blood returning the lungs or leaving to the rest of the body. Their heart completely separates oxygenated and deoxygenated blood The different pressures allow them to move blood quickly through their body without endangering their alveoli. The crocodile heart is thought to be the most efficient and complex heart known to science Crocodiles also have a special valve which allows the to cut off blood to the lungs, and the extra blood is shot from the left aorta to the right aorta Digestion Crocodiles have the most acidic stomach of any vertebrate, allowing them to digest bone, hooves, and horns Some swallow stones to aid in digestion and to act as ballast Crocodiles have developed sharp teeth to grab onto prey and tear, a large part of their hunting Their stomach resembles that of birds, with a gizzard, unlike other reptiles. A crocodile's stomach contains two chambers, one grinds up food while the other contains a digestive system which remove nutrients Crocodiles swallow their food whole if possible, other wise they tear their food into smaller chunks. Reproduction Crocodiles reproduce by laying eggs, like all other reptiles Mating takes place in the water Crocodiles do not have sex chromosomes, instead the gender depends upon the temperature of the eggs At 30 degrees Celsius they are males, at 31 they are both sexes, at 32 degrees they are males, and at 33 they are females. Incubation period is about 80 days Females can store sperm until conditions are right. Waste Removal Crocodiles lack a urinary bladder, instead they excrete it directly after it is removed from the bloodstream by the kidneys Crocodiles have three kidneys which are developed early in embryonic development Crocodiles excrete nitrogenous wastes in liquid form, with liquid between 40% and 70% ammonia Water Balance Saltwater crocodiles get their drinking water from their food, they cannot drink saltwater Salt glands in mouth excrete salt and potassium to maintain electrolyte and internal water balance while out of water, and become larger or smaller depending on the level of salt in the water Transport Crocodiles and humans have very similar hearts, each with four chambers. However, crocodiles can shut off one of their ventricles to save oxygen, unlike humans Both crocodiles and humans have different pressures in their hearts, so they can quickly pump blood without damaging the alveoli in the lungs Crocodiles have a special valve which humans do not, it allows them to completely cut off blood the their lungs to save oxygen when they are underwater Digestion Both humans and crocodiles have a stomach which connects to their mouth by their esophagus, where nutrients are digested However, a crocodiles stomach is divided into two, one which breaks down the food, and the other which takes in nutrients A crocodile also only has one intestine, which does the job of both the large and small intestines in humans A crocodiles stomach is much more acidic than a humans, due to the food it eats. Waste Removal Both humans and crocodiles filter nitrogenous wastes through their kidneys, however, crocodiles have three sets of kidneys while human have one While humans excrete wastes as urea, crocodiles excrete their nitrogenous wastes as uric acid. However, in humans urine is first sent to a urinary bladder, while in crocodiles it is excreted directly after being filtered from the bloodstream Water Balance In both humans and crocodiles kidneys take care of most of the water balance However, crocodiles have salt glands which help them balance the salt from the salt water Reproduction While both crocodiles and humans both reproduce heterosexually, crocodiles lay eggs while humans birth live offspring Also, humans have sex chromosomes while crocodiles do not. Blood flows into the nephron from the glomerus and, as it is under pressure, it filters through the capillaries and into the bowman's capsule. Glucose, salts, amino acids and some vitamins are filtered through, while the plasma remains because of its size.
The remaining waste is excreted as urea. Gas Exchange Works Cited "Nile Crocodile Fact Sheet." Nile Crocodile Fact Sheet. San Diego Zoo Global, 01 May 2010. Web. 15 May 2013. Hosking, Chris. "Freshwater Crocodile - Australian Museum." Freshwater Crocodile - Australian Museum. Australian Museum, 01 Nov. 2010. Web. 15 May 2013. "The Reptipage: Crocodylian Bodyplans." The Reptipage: Crocodylian Bodyplans. N.p., 07 Sept. 2012. Web. 15 May 2013. "reptile." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2013. Web. 30 May. 2013. <http://www.britannica.com/EBchecked/topic/498684/reptile>. Britton, Adam. "Crocodilian Biology Database - General Biology." Crocodilian Biology Database. Adam Britton, n.d. Web. 15 May 2013.