Lecture 5
Circulatory system:
· Two half’s of the heart the left and right
o Left half is for the systemic system
o Right half is for the pulmonary system
· Atrium receives the blood, and the ventricle pumps blood out
· Closed circulatory system: blood stays inside the circulatory system
o Distribution of specific ions or nutrients occurs only at specific regions the capillaries.
· Mammals and birds have 4 chambers two atria and two ventricles
o Therefore there are two loops
· In fishes there is only a two chambered heart… only a single atium and a ventricle
o There is a sinus venosus
§ Bony, jawless, n ___ have this type of heart
o Blood leaves ventricles and goes to gills then goes to the rest of the body
o There are two capillary beds in series… one at the gills the other at the body parts
o Blood goes from sinus anosus into the atrium into the ventricle into another expansion of a blood vessel then into the aorta
· In amphibia: frogs have 3 chambers!
o Two atria and only one ventricle
§ Some blood that leaves ventricle goes to skin some goes to the lungs- this blood pours out into either the left or right atrium
ú Which atrium it goes to depends on where the capillaries are located
§ Some blood goes into the gut/muscles then back to the right atrium
§ There are many groves that tend (trys) to keep deoxygenated and oxygenated blood seperate
· Reptilia also have three chambers – lizards snakes and many tutrles
o Two atria and a ventricle
o There is a partial wall that separates the two halves of the ventricle. It is not a full wall
§ Helps avoid mixing of deoxygenated and oxygenated blood
· Crocodilian heart has 4 chambers
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· Resistance to blood flow in blood vessels depends on diameter
· Blood coming from lungs tends to be sent to systemic loop, de oxygenated blood tends to be sent to the pulmonary loop
· Vertebrates have closed circulatory systems
· Closed circulatory systems are very effective in distrubiting blood in a specific pattern, ensures blood will pick up oxygen at a certain location give off co2 and pick up nutrients at a certain location and deliver it to all over the body
o Pushing blood through all the tubing requires a lot of pressure= muscle contraction in heart using up a lot of atp, animal must eat alot
· Open circulatory system. They have a heart, and have a fluid like blood. Some have vessels and some don’t.
o Hemolymph= is open circulatory blood
o Very little pressure is required, heart does not need to use up a lot of at, so the animal doesn’t need to eat too much
o There are no fixed pathways that the blood flows through, and because of this there is not nearly as good a guarantee that every part of the body will receive nutrients and gasses on a regular basis
· Invertebrates has an enormous variation in circulatory system plan
o most of the annelid worms have closed circulatory systems
o cephalopoda (octopus, squid, cuttle fish, chambered mol.. )
o most invertabrates have open circulatory system
