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BIOL Exam II - Ex 10
Comparative Anatomy
Question | Answer |
---|---|
What did you do in this exercise? | - Observe the external/internal structures of a crayfish - - Observe the external/internal structures of a rat - Study anatomical differences between male and female rats and crayfish |
What anatomical plane is similar to a cross section? | transverse plane |
Crayfish are placed in the phylum ___. | arthropoda |
Rats are placed in the phylum ___. | chordata |
The heart and arteries of the crayfish will be red in color because they ___. | have been injected with red latex |
The gills are located under the ___. | carapace |
The position of the esophagus is ___ to the trachea. | dorsal |
How is the uterus in the female rat different from that of humans? | the rat's uterus consists of a pair of elongated uterine horns |
What is the site of nutrient and mineral absorption in the rat? | small intestine |
The rat and crayfish carcasses and any dissected parts are considered to be a(n) ___ and should be most safely discarded ___. | - biohazard - in the "animal carcass disposal" container |
Is a crayfish a deuterostome or protostome? Why? | - a protostome; its mouth forms first - it is an arthropod |
What is an arthropod? | - an invertebrate animal having an exoskeleton, a segmented body, and jointed appendages - form the phylum Arthropoda, and include the insects, arachnids, myriapods, and crustaceans |
How are the bodies of crayfish divided up? How many segments are in them? | - into two major body regions: the (anterior) cephalothorax and the (posterior) abdomen - the cephalothorax is made up of 14 body segments - the abdomen is made up of 6 body segments |
What’s carapace? Where is it located? Function? | - hard portion of the exoskeleton - covers the dorsal surface of the cephalothorax - protection |
What is the purpose of the antennas? Antennules? | - sense other organisms - sense other organisms and help balance the crayfish |
What does ommatidia mean? | - the compound eyes of arthropods like insects, crustaceans and millipedes are composed of units called ommatidia - an ommatidium contains a cluster of photoreceptor cells surrounded by support cells and pigment cells; appear hexagonal |
Why does the structure/location of the mandibles make sense? What are maxillipeds? | - the mandibles cover the mouth; they bite food into bits small enough to swallow - maxillipeds hold food, touch, and taste |
How many pairs of walking legs are there? What’s the first pair called? What are they used for? | - 5 - chelipeds - used for protection and for feeding |
What/where is the nephridopore? | - part of their excretory system (for removing nitrogenous waste); crayfish propel water from the rear to the front and out the nephridiopores - they are located ventral to the eyes |
What is the difference between male and female crayfish? (Swimmerets, genital pores, and seminal receptacle.) | - males: first two pairs of swimmerets are modified to deliver sperm to female crayfish; genital openings - females: have gential pores between the 2nd and 3rd pairs of legs; have a small opening (seminal receptacle) between the 4th pair of legs |
What type of circulatory system does a crayfish have? Where does the blood drain to be oxygenated? Where does the heart lie? (Dorsal or ventral—think about why.) | - open - heart is dorsal; in thorax - it receives blood from the body cavity and pumping it into arteries for distribution to the body; drains into sinuses; oxygenated by gills |
What’s unique about the crayfish respiratory system? What’s a gill? | - a gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting CO2 - the microscopic structure of a gill presents a large surface area to the external environment |
Explain how the crayfish stomach works. | - food passes through the mouth and the esophagus to the 2-chambered stomach in the thorax - 1st is the cardiac chamber; has chintinous teeth (gastric mill); mechanical digestion - 2nd is the pyloric chamber; chemical digestion |
What’s the function of the green glands? | - major excretory organs (like kidneys); help to filter, process and remove impurities and waste products on a daily basis - base of each antenna |
What are the ganglia? | swellings around the ventral nerve cord that provide relay points and connections between different neurological structures in the body |
Where is the brain located in a crayfish? | - in the head - anterior/cranial to the stomach |
Why are cephalochordates, urochordates, and vertebrates in the same phylum? | all develop notochords (spinal column in vertebrates) |
What are 4 defining features of a chordate? The presence of ___ in the embryo and/or adult. | - pharyngeal gill slits - dorsal hollow nerve cord that runs the length of the body, w/ projections from neurons - supportive but flexible rod, called the notochord, that runs the length of the body - segmented body and muscular post-anal tail |
What defines the vertebrates? | - a column of cartilaginous or bony structures called vertebrae - the cranium (skull) |
What defines mammals? | - insulating hair or fur - mammary glands for lactation - endothermy—they regulate their body temperatures with internally generated heat |
What is a defining characteristic to animals in the order rodentia? | have two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing |
Brown rats are nocturnal omnivores with poor vision so they must rely on smell and touch. They are also extremely social creatures that reproduce often. Try to tie these characteristics to some of the structures. | - whiskers - nose - uterine horns - large testis |
State the function of the following structures, and whether they belong to humans or rats: uvula, gall bladder, appendix, and cecum. | - uvula: produces saliva quickly, helps with speech; humans - gall bladder: stores and concentrates bile; humans - appendix: unknown; humans - cecum: harbors microorganisms that aid in digestion, esp. with cellulose; humans and rats |
The uterus of a rat is shaped differently than that of a human, how? Why are the testes so large? | - uterine horns in rats; able to support multiple fetuses - 1 pear-shaped uterus in humans; best supports 1 fetus - testis large so more sperm is produced |
What type of circulatory system does a rat have? What is the cavity that the heart is contained in called? | - closed - thoracic/chest cavity; ventral |
Know the chambers of the heart, and how blood flows in the body. Which way does blood flow in arteries? Veins? | - deox. blood from the body -> right atrium -> right ventricle -> pulmonary artery -> lungs -> ox. blood to pulmonary veins -> left atrium -> left ventricle -> body - blood flows away from the heart in arteries - blood flows away from the heart in veins |
What does the diaphragm do? | vital to respiration: as the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs (b/c negative pressure) |
Know the differences between the male and female rat. | - male: large testes, penis - female: mammary glands, vulva |
What’s the purpose of the liver? Why is this especially important for rats? | - the liver filters and processes blood as it circulates through the body, metabolizes nutrients, detoxifies harmful substances, makes blood clotting proteins, etc. - important b/c rats eat almost anything |
Where does the bile go since rats don’t have a gall bladder? | - since no gall bladder, bile is less concentrated - bile collects in the ducts and passes directly to the small intestine |
What’s the purpose of the large intestine? | absorb water from the remaining indigestible food matter and transmit the useless waste material from the body |
What is the purpose of the pancreas? | - part of the digestive system and produces important enzymes and hormones that help break down foods - endocrine function because it releases juices directly into the bloodstream - exocrine function because it releases juices into ducts |
What is the cecum? | - large sac at the intersection of the large and small intestine - harbors microorganisms that aid in digestion |
What do the kidneys do? You can follow the ___ from the kidneys to the bladder. | - salt and water balance; elimination of toxic wastes - ureters |