!+Star+Fish+!

= = = Star Fish vs Human Nature = = By Angela Howes and Rebecca Judhan =



** Human Anatomy **
Digestive System

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 * The digestive process starts in the **mouth**. Food is broken down by teeth and the chemical action of salivary enzymes produced by **salivary glands**. Starches are broken down into very small molecules at this point. After being chewed and swallowed, the food enters the **esophagus** which is a long tube connecting the mouth and stomach. Rythmic, wave-like musclue movements are used to push food down into the stomach. Once in the **stomach** the food is churned and bathed in a very strong acid. Food then enters the duodenum, the first part of the **small intestine**. Then it enters the jejunum and then the ileum (the final part of the small intestine). Bile (produced in the **liver** and stored in the **gallbladder**), pancreatic enzymes (produced in the **pancreas**), and other digestive enzymes produced by the inner walls of the small intestine help break down the food. Food then passes through the **large intestine** where some water and electrolytes are removed from the food. Many other nutrients are absorbed by the large intestine as it travels up the colon, across the abdomen and down the other side of the body.

Excretory system

> function in both sexes to pass urine. >[]
 * The excretory system removes unnecessary materials from the body. The **kidneys** main function is to remove waste from the bloodstream. Kidneys also maintain volume of extracellular fluid, maintain ionic balance in extracellular fluid, maintain pH and osmotic concentration of the extracellular fluid, and excrete toxic metabolic by-products (such as urea, ammonia, and uric acid). With about 1 million nephrons in each kidney, it is able to complete these tasks. They act as fillers in the kidney. The **ureters** move the urine from the kidney to the urinary bladder. In adults, the ureters are usually 25- 30 cm long. The **urinary bladder** collects urine excreted by the kidneys before being disposed of by urination. It is a hollow and elastic muscular organ that sits on the pelvic floor. The **urethra** is a tube that connects the urinary bladder to the outside of the body. It has an excretory

Respiratory System

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 * The **nose** is the first and last organ that air passes through. It cleans the air of dust and other impurities, warms the air if it is too cool, and moistens the air if it is too dry. After air passes through the nostrils, it passes through the **nasal cavity** where it is purified made to the bodies liking. The **pharynx** is most commonly known as the throat. It moves the air into the lungs. The pharynx is about 5 inches long and is separated in 3 distinct regions: the nasopharynx, the oropharynx, and the laryngopharynx. The **larynx**, also known as the voice box, is what allows you to speak. The larynx contains an inlet at the top which allows substances to pass through or not. The inlet is wide open when air is breathed so it can enter your lungs. The **trachea** connects the larynx to the bronchi. this organ is different than the others because it is flexible. It is made up with cartilage rings in the shape of a "C". It then branches off into two main **bronchi**. Each bronchi enters its lung and begins on a series of branches called bronchial. Each branch continues to branch into smaller and smaller bronchioles. The final branch is called the terminal bronchioles. The bronchioles are covered in sacs that are filled with **alveoli**. They are covered in inter linking capillaries which is where blood flows through. **Respiration** begins when the terminal bronchioles lead into the respiratory bronchioles.

Circulatory system

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 * The Circulatory system consists of a **four-chambered heart** with two atria and two ventricles. Deoxygenated and oxygenated blood are not mixed. The four chambers ensure efficient and rapid movement of highly oxygenated blood to the organs of the body. A **beating heart** contracts and relaxes. The conduction system keeps your heart beating in a coordinated and normal rhythm, which in turn keeps blood circulating. Contraction is called systole, and relaxing is called diastole. **Blood vessels** called coronary **arteries** extend over the surface of your heart and branch into smaller **capillaries**. Blood vessels are part of a closed extensive network of narrow elastic passageways whose main function is to circulate blood to all the far out places of the body. There are two kinds of blood vessels: arterial **arteries** (carry blood away from the heart) and venous **veins**(carry blood toward the heart to be repumped). The human body contains about 9.5 pints, 4.5 liters, 6 quarts of **blood**. It is the medium through which the entire body is nourished and supported carrying nutrient molecules from digested foods, as well as carrying away harmful waste products such as carbon dioxide. Our blood contains a watery liquid part called **plasma** and makes up about 55 percent of the volume of blood. Plasma is over 90% water and enables our blood to navigate fast moving substances in solution and slow moving thicker substances in suspension. **Platelets** are very tiny vital blood components lacking nuclei and are one fourth of the size of red blood cells. Platelets travel with the blood and assist to prevent us from bleeding to death even with the smallest of wounds. **Hemoglobin** is a complex iron protein substance. It is the component of red blood cells which gives red blood cells their special oxygen carrying proficiency as well as their color.

Nervous system >[|http://kidshealth.org/kid/htbw/brain.html#] >[] >[]
 * The biggest part of the brain is the **cerebrum**. The cerebrum makes up 85% of the brain's weight. It is the thinking part of the brain and it controls your voluntary muscles. The **cerebellum** is at the back of the brain, below the cerebrum. It's a lot smaller than the cerebrum at only 1/8 of its size. It controls balance, movement, and coordination. The anterior parts of the cerebral hemispheres are called the **olfactory bulbs**. It receives input from the olfactory nerves (smell). The olfactory bulbs of primitive vertebrates comprise a large proportion of the cerebrum. The **optic lobe** consists either of two lobes of the dorsal mesencephalon, containing primary visual centers.The **medulla oblongata** is a portion of the hindbrain that controls autonomic functions such as breathing, digestion, heart and blood vessel function, swallowing and sneezing. Within the **spinal cord** you can find the association neuron. This neuron composes the majority of the spinal cord, and serves as an integration center or interpretation center, of sensory neurons and motor neurons. A sensory neuron informs the body of its environment, the association neuron interprets the information, and responds to the environment with the motor neuron.

Locomotion (muscular and skeletal systems)

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 * The **axial skeleton**, making up 80 of your 206 bones, encompasses all your upper body bones. It's main purposes are to protect your vital organs, such as the brain, heart, and lungs, and to provide an efficient structure to preform a variety of work. The **appendicular skeleton** refers to your arms and legs. The fibrous, flexible, elastic connective tissue found in the human skeleton is **cartilage.** In the human embryo, the skeleton is made up mostly of cartilage. By adulthood, most of the cartilage has been replaced by bone. In the adult, cartilage is found in the nose, ears, and trachea, at the ends of ribs and other bones, and between the vertebrae. At the ends of bones, cartilage provides flexibility. Between bones, cartilage provides cushioning. In the ears, nose, and trachea, cartilage provides flexible, rather than rigid, support. Bones are connected at places called **joints**. Most joints allow bone movement. Ball and socket joints are located at the hip and shoulder. They permit circular movement. Hinge joints are located at the elbows and knees. They allow a back and forth movement. Hinge joints do not permit as much movement as ball and socket joints. Pivot joints are found where the skull joins the vertebral column. **Skeletal muscles** are attached to the bones of the skeleton. The bones and body parts are moved by the contraction of these muscles. Skeletal muscles usually function in opposite pairs. ** Smooth muscle ** is found in the walls of arteries and organs of the body. Contraction of smooth muscle is controlled by the nervous system. **Cardiac muscle**, found in the walls of the heart. causes the heart to beat. **Tendons** and ligaments are both composed of connective tissue. Tendons are bands of dense tissue that connect muscles to bones

Star Fish Anatomy
Taxonomy: The common starfish is named Asterias rubens >[]
 * Phylum: Echinodermata
 * Subphylum: Asterozoa
 * Class: Asteriodea
 * Family: Asteriidae
 * Genus: Asterias
 * Species: Rubens

__ Question and Answer __

Q: Where is a Starfish's Habitat? A: A Starfish normally lives in a shallow marine environmet, but they can usually be found in the intertidal zone.

Q: How do Starfish mate? A: " Sea stars are capable of both sexual and asexual reproduction. Individual sea stars are male or female. Fertilization takes place externally, both male and female releasing their gametes into the environment. Resulting fertilised embryos form part of the zooplankton." []

Q: What Do Starfish eat? A: "Most sea star species are generalist predators, some eating bivalves like mussels, clams, and oysters; or any animal slow enough to be unable to evade the attack (e.g. dying fish). Some species are detritivores, eating decomposed animal and plant material, or organic films attached to substrate. The others may consume coral polyps (the best-known example for this is the infamous Acanthaster planci), sponges or even suspended particles and planktons (sea stars from the Order Brisingida). The process of feeding or capture may or may not be aided by special parts; Pisaster brevispinus or Short-spined Pisaster from west coast of America may use a set of specialized tube feet capable of extending itself deep into the soft substrata, hauling out the prey (usually clams) from within." []

Digestive System/ Excretory System

Sea star digestion is carried out in two separate stomachs, the cardiac stomach and the pyloric stomach. The cardiac stomach, which is a sack like stomach located at the center of the body may be everted - pushed out of the organism's body and used to engulf and digest food. Some species take advantage of the great endurance of their water vascular systems to force open the shells of bivalve mollusks such as clams and mussels, and inject their stomachs into the shells. Once the stomach is inserted inside the shell it digests the mollusk in place. Because of this ability to digest food outside of its body, the sea star is able to hunt prey that are much larger than its mouth would otherwise allow including arthropods, and even small fish in addition to mollusks. Some echinoderms have been shown to live for several weeks without food under artificial conditions—it is believed that they may receive some nutrients from organic material dissolved in seawater." []





Respiratory System/Circulatory System

"Starfish are almost unique in the fact that, unlike most other animals, they do not have blood but instead use sea water to pump around their bodies. The water vascular system uses cilia and the constantly contracting ampullae to keep things moving. An ionic imbalance causes water to flow into the madreporite, entering the water vascular system. Some of this water is diverted into the perivisceral coelom (the large cavity in which major organs are suspended), where it is circulated by the beating of cilia. Most oxygen enters the starfish via diffusion into the tube feet (with the water vascular system), or the papulae (small sacs covering the upper body surface)." []



Nervous System

"Echinoderms have rather complex nervous systems, but lack a true centralized brain. All echinoderms have a nerve plexus (a network of interlacing nerves), which lies within as well as below the skin. The esophagus is also surrounded by a number of nerve rings, which send radial nerves that are often parallel with the branches of the water vascular system. The ring nerves and radial nerves coordinate the starfish's balance and directional systems. Although the echinoderms do not have many well-defined sensory inputs, they are sensitive to touch, light, temperature, orientation, and the status of water around them. The tube feet, spines, and pedicellariae found on starfish are sensitive to touch, while eyespots on the ends of the rays are light-sensitive." []

Locomotion " Sea stars move using a water vascular system. Water comes into the system via the madreporite. It is then circulated from the stone canal to the ring canal and into the radial canals. The radial canals carry water to the ampullae and provide suction to the tube feet. The tube feet latch on to surfaces and move in a wave, with one body section attaching to the surfaces as another releases. Most sea stars cannot move quickly. However, some burrowing species like sea stars from genus Astropecten and Luidia are quite capable of rapid, creeping motion - it "glides" across the ocean floor. This motion results from their pointed tubefeet adapted specially for excavating local area of sand." []