Lab #11

interval

An ... is a time measurement that includes waves and/or complexes;

open circulatory system

Arthropods and most molluscs have an ... in which the circulatory fluid comes into direct contact with body tissues during circulation. -In these animals, the circulatory fluid, called HEMOLYMPH, is also the interstitial fluid that bathes body cells. -Contraction of one or more hearts pumps the hemolymph through the circulatory vessels into interconnected SINUSES, spaces surrounding the organs. -Within the sinuses, exchange of substances occurs between the hemolymph and body cells. -Relaxation of the heart draws hemolymph back in through pores, which are equipped with valves that close when the heart contracts. -Body movements help circulate the hemolymph by periodically squeezing the sinuses. -open circulatory system of larger crustaceans, such as lobsters and crabs, includes a more extensive system of vessels as well as an accessory pump. -The lower pressures associated with open circulatory systems make them less costly than closed systems in terms of energy expenditure. heart, hemolymph in sinuses surrounding organs, pores, tubular heart

Waste products

-... of cellular metabolism, such as carbon dioxide and urea (CH4N2O; nitrogenous waste from protein degradation), are transported from body cells to the lungs and kidneys via blood, where they are eliminated.

segment

A ... is a time measurement that does not include waves and/or complexes, in other words, segments are flat portions of the ECG

fish

A ... that lives in water has a 2 chambered heart -so its heart has 2 chambers its separated by a valve and the reason why its because they live in water. -one single loop The blood is going to go to the gills where its going to get oxygen and then it's going to go to the body and then it's going to continue back to the heart. -this works great in water

heart

A circulatory system has three basic components: a circulatory fluid, a set of interconnecting vessels, and a muscular pump, the ... -the ... powers circulation by using metabolic energy to elevate the pressure of the circulatory fluid which then flows through the vessels and back to the heart. -Several basic types of circulatory systems have arisen during evolution. Circulatory systems are either open or closed, vary with regard to the number of circuits in the body, and rely on pumps that differ in structure and organization.

electrocardiogram

-Faint traces of the electrical activity occurring along the heart wall spread through the rest of the body and create changes in the electrical potential of the skin. -These electrical changes can be detected by electrodes on the skin and recorded in an ... (ECG, or EKG from the German spelling). -The resulting graph of current against time has a characteristic shape that represents the stages in the cardiac cycle. -The normal ECG tracing is a flat baseline interrupted by a series of waves.

Capillaries

-are microscopic vessels with thin, porous walls. -Networks of these vessels, called capillary beds, infiltrate every tissue, passing within a few cell diameters of every cell in the body. -Across the walls of capillaries, chemicals, including dissolved gases, are exchanged by diffusion between blood and interstitial fluid around cells. -At their "downstream" end, capillaries converge into venules, and venules converge into VEINS, the vessels that carry blood back to the heart.

Frogs and other amphibians

-have a heart with three chambers: two atria and one ventricle. -A ridge within the ventricle diverts most (about 90%) of the oxygen-poor blood from the right atrium into the pulmocutaneous circuit and most of the oxygen-rich blood from the left atrium into the systemic circuit, so that there is minimal mixing of oxgyen-poor and oxygen-rich blood. -In the three-chambered heart of turtles, snakes, and lizards, an incomplete septum partially divides the single ventricle into separate right and left chambers.

heart

-lets start with the heart then because its important that we understand the chambers of the heart and where blood is essentially going -remember that for the heart image the right is your left and that the left is your right -deoxygenated blood: means that its coming back from your body. its coming from your superior and inferior vena cava. So basically its entering into what's called your right atrium. It then goes through a valve. this valve is called the AV valve sometimes we call it the tricuspid valve, but the blood is now going to go from here into the ventricles. So its going to go into your right ventricle. its then going to move out through the semilunar valve, its going to move into what's called the pulmonary artery. -Pulmonary artery: interesting because its an artery that has deoxygenated blood. the reason why is because its headed to the lungs. blood is going out that artery. that's what an artery is. it moves away from the heart into the lungs and now it becomes oxygenated. -so that oxygenated blood is going to come back into your left atrium its then going to flow through our left AV valve down into our left ventricle -then its going to move out the back into this big artery called the Aorta -so it goes through the aorta down at the bottom and then this aorta as it moves up at the top is going to send up arteries that go up to the head. -its then going to go to the body and then its going to came back again.

Evolution of Circulatory Systems

-unicellular organisms, exchange occurs directly with the external environment. -multicellular organisms, however, direct transfer of materials between every cell of the body and the environment is not possible because diffusion of materials is rapid only over very small distances (less than a few millimeters). -Natural selection has resulted in two general solutions to the need for exchange in animals: 1)The first solution is a body size and shape that keep many or all cells in direct contact with the environment, allowing each cell to exchange materials directly with the surrounding medium. found only in certain invertebrates, such as cnidarians and flatworms. 2) found in all other animals, is a circulatory system that moves fluid between the tissues where exchange with the environment occurs (e.g. gills, lungs, small intestines, kidneys) and each cell in the body. -Animals about the size of earthworms and larger require circulatory systems to move substances around their bodies; thus, circulatory systems were a necessary step in the evolution of complex, larger animals.

birds and mammals

-we have a 4 chambered heart -what we've done is sealed up the 3rd chamber. and now we have 4 chambers -while still maintaining that double loop -those have evolved as we've had different constraints depending on the environment and where they live.

cardiac cycle

-your heart goes through a cardiac cycle -the cardiac cycle is going to have 2 parts to it, it has diastole and systole -diastole means filling -systole means pumping. -if you were to take a turkey baster. and so what you do is squeeze the bulb at the top and that like systole. you're squeezing it and the liquid would flow out. and then when you relax it, its going to suck that fluid back into it. -the heart is going to have a systole when it contracts and then its going to have a diastole where its relaxing. and so we have to time it as well. because if the whole thing were to contract that wouldn't work. -and so basically what you have is the systole up here where you're contracting the atrium and that pushes it down into your ventricle -your ventricle at that point would be relaxed and then as we pump our ventricle its going to move it back in this direction and we're going to have relaxation of the atrium so we can get new blood flowing into it. And so what you hear in a heart is that lab dub. and why do we hear that? well you're getting that contraction of the atrium. and then they relax and then contraction of the ventricle. And the ventricle is more powerful because it has to push it into the lungs or it has to push it to rest of the body. And so its going to be way more muscle than we have down here in the ventricles that we do in the heart. And we're going to have way more on the left side because that has to push it all the way around the whole body. so timing is important as well.

Oxygen

... is used during aerobic respiration to release energy from acquired nutrients. -Gas exchange occurs when oxygen from the atmosphere passes into the respiratory system of the animal, where it crosses cells in the lungs/gills/skin and enters the circulatory system for transport to body cells.

cardiovascular system

Blood circulates to and from the heart through arteries, veins, and capillaries. Within each type of blood vessel, blood flows in only one direction

interstitial fluid

Exchange occurs as substances dissolved in aqueous solution outside of a cell (e.g. interstitial fluid(extracellular fluid between cells)) move across the plasma membrane to enter a cell, and vice versa. -for an animal to receive the benefits of nutrients processed by the digestive system (e.g. glucose, amino acids), these nutrients must pass across intestinal cells and into blood vessels to be transported to all cells of the animal's body. -Only then can the nutrients cross plasma membranes to enter body cells, where they can be utilized.

cell layers

For animals with many ..., diffusion distances are too great for adequate exchange of nutrients and wastes by a gastrovascular cavity -In these organisms, a circulatory system minimizes the distances that substances must diffuse to enter or leave a cell.

autorhythmic

Function of the Circulatory System -In vertebrates, the heartbeat originates in the heart itself. -Some cardiac muscle cells are ... meaning they can contract and relax repeatedly without any signal from the nervous system.

cardiac cycle

Function of the Circulatory System -One complete sequence of pumping and filling (i.e. one heartbeat) is referred to as a ... -The contraction phase of the cycle is called SYSTOLE, and the relaxation phase is called DIASTOLE. -During one cycle, the two atria contract simultaneously while the ventricles are relaxed. Then, the atria relax and the two ventricles contract simultaneously, and then relax. -During the cycle, changes in blood pressure inside the chambers and great arteries cause the heart valves to open and close. -These events regulate the flow of blood through the heart and into the systemic and pulmonary circuits.

atrioventricular node

Function of the Circulatory System During atrial contraction, the impulses originating at the SA node reach other autorhythmic cells located in the wall between the left and right atria, the .... -Here the impulses are delayed for about 0.1 second before spreading to the ventricles -This delay allows the atria to empty completely before the ventricles contract. -Then the impulses from the AV node are conducted rapidly throughout the ventricular walls by specialized cardiac muscle cells called the AV bundle, bundle branches and Purkinje fibers, leading to ventricular contraction. -Because electrical impulses have left the atria, they are in relaxation. -Thus, electrical signals cause the mechanical pumping action of the heart; mechanical events always follow the electrical events.

sinoatrial node

Function of the Circulatory System -A group of autorhythmic cells in the wall of the right atrium (near where the superior vena cava enters the heart) called the .... or pacemaker, sets the rate and timing at which all cardiac muscle cells contract -The ... node generates electrical impulses much like those produced by neurons.

gap junctions

Function of the Circulatory System -Because cardiac muscle cells are electrically connected through ... (pores between adjacent cardiac muscle cells that permit ion flow), impulses from the SA node spread rapidly within heart tissue. -Impulses from the SA node first spread rapidly through the walls of the atria, causing both atria to contract in unison.

SA node

Function of the Circulatory System -The ... sets a heart rate of 100 beats per minute (bpm), yet resting heart rate is often lower than this (~75 bpm for an average healthy adult). -This is because both the heart rate and strength of contraction are modified by input from the nervous system. -Two portions of the nervous system, the sympathetic and parasympathetic divisions, are largely responsible for this regulation.

alligators and other crocodilians

In ... , the ventricles are divided by a complete septum, which is technically a four-chambered heart.

mammals

In ... for example, oxygen from inhaled air diffuses across only two layers of cells in the lungs to reach the blood. Blood vessels then carry this oxygen-rich blood to all parts of body. -As the blood travels throughout body tissues in tiny blood vessels, oxygen in the blood diffuses only a short distance before entering the interstitial fluid that directly bathes the cells.

mammals and birds

In ..., there are two atria and two completely divided ventricles. -The left side of the heart receives and pumps only oxygen-rich blood, while the right side receives and pumps only oxygen-poor blood. -As endotherms, ... use about ten times as much energy as equal-sized ectotherms. -Their circulatory systems therefore need to deliver about ten times as much fuel and oxygen to their tissues (and remove ten times as much carbon dioxide and other wastes). -This large traffic of substances is made possible by separate and independently powered systemic and pulmonary circuits and by large hearts that pump the necessary volume of blood. -A powerful four-chambered heart arose independently in the distinct ancestors of mammals and birds and thus reflects convergent evolution.

closed circulatory system

In a ... circulatory fluid called BLOOD is confined to vessels and is distinct from the interstitial fluid. -One or more hearts pump blood into large vessels that branch into smaller ones that infiltrate the organs. -Exchange occurs between the blood and interstitial fluid, and then between the interstitial fluid and body cells. -Annelids, cephalopods, and all vertebrates have closed circulatory systems. -The benefits of closed circulatory systems include relatively high blood pressures, which enable the effective delivery of oxygen and nutrients to the cells of larger and more active animals. -Among the molluscs, for instance, closed circulatory systems are found in the largest and most active species, the squids and octopuses. -Closed systems are also particularly well suited to regulating the distribution of blood to different organs. -heart, interstitial fluid, blood, small branch vessels in each organ, dorsal vessel (main heart), axillary hearts, ventral vessels

P wave

In a single cardiac cycle, the ... indicates the DEPOLARIZATION* (see note below) of the atria just prior to the beginning of atrial systole -*Most cells in higher organisms maintain an internal environment that is negatively charged relative to the cell's exterior. This difference in charge across the membrane is called the cell's MEMBRANE POTENTIAL. In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive. The change in charge typically occurs due to an influx of positively charged sodium ions (Na+) into the cell. During an action potential, the depolarization is so large that the potential difference across the cell membrane briefly reverses polarity, with the inside of the cell becoming positively charged. -Depolarization is necessary for muscle contraction to occur. BUT, DEPOLARIZATION IS NOT THE SAME AS CONTRACTION; RATHER DEPOLARIZATION IS THE ELECTRICAL SIGNAL THAT IMMEDIATELY PRECEDES CONTRACTION. -Repolarization refers to the change in membrane potential when the inside of the cell returns to its normal negative value, just after the depolarization phase. Repolarization precedes relaxation.

Single Circulation

In fish, the heart consists of two chambers: an atrium and a ventricle. -The blood passes through the heart once in each complete circuit, an arrangement called ... -Blood entering the heart collects in the atrium before transfer to the ventricle. -Contraction of the ventricle pumps blood to the gills, where there is a net diffusion of oxygen into the blood and of carbon dioxide out of the blood. -As blood leaves the gills, the capillaries converge into a vessel that carries oxygen-rich blood to capillary beds throughout the body. -Blood then returns to the heart. -In ..., blood that leaves the heart passes through two capillary beds (gill capillaries and systemic capillaries) before returning to the heart. -When blood flows through a capillary bed, blood pressure drops substantially -The drop in blood pressure in the gills as blood flows through gill capillaries limits the rate of blood flow throughout the rest of the fish's body. -As the fish swims, however, the contraction and relaxation of its muscles help accelerate the relatively sluggish pace of circulation.

insects

Insects don't have actual blood they have this thing called hemolymph -it is both blood and interstitial fluid -interstitial fluid is going to be the fluid that bathes the cells inside us -in insects those things are combined together that why when you squish a bug you get that goo that comes out of the bug. -OPEN CIRCULATORY SYSTEM

pulmonary circuit

One pump, the right side of the heart, delivers oxygen-poor blood to the capillary beds of the gas exchange tissues (lungs/skin), where there is a net movement of oxygen into the blood and of carbon dioxide out of the blood -This type of circulation is called a ... if the capillary beds involved are all in the lungs, as in reptiles and mammals.

pulmocutaneous circuit

One pump, the right side of the heart, delivers oxygen-poor blood to the capillary beds of the gas exchange tissues (lungs/skin), where there is a net movement of oxygen into the blood and of carbon dioxide out of the blood. -It is called a .... if it includes capillaries in both the lungs and the skin, as in many amphibians.

Invertebrates

Some animals lack distinct circulatory systems. These animals, whose body walls are exceedingly thin, comprised of only a few cell layers, exchange materials directly with their environment.

heart

The ... of all vertebrates contain two or more muscular chambers. -The number of chambers and the extent to which they are separated from one another differ substantially among vertebrates. These important differences reflect the close fit of form to function that arises from natural selection.

QRS complex

The ... represents the depolarization of the ventricles, which immediately precedes ventricular systole.

pericardial cavity

The Mammalian Heart -The heart lies in the ... within the thoracic cavity. -It consists mostly of cardiac muscle. -The two atria have relatively thin walls and serve as collection chambers for blood returning to the heart from the lungs (left atrium) or other body tissues (right atrium). -The ventricles have thicker walls and contract much more forcefully than the atria, especially the left ventricle, which pumps blood to all body organs through the systemic circuit. -Although the left ventricle contracts with greater force than the right ventricle, it pumps the same volume of blood as the right ventricle during each contraction. -Four valves in the heart, made of flaps of connective tissue, prevent backflow and keep blood moving in the correct direction.

Semilunar valves

The Mammalian Heart are located at the two exits of the heart: where the aorta leaves the left ventricle (AORTIC SEMILUNAR VALVE) and where the pulmonary artery leaves the right ventricle (PULMONARY SEMILUNAR VALVE). -These valves are pushed open by the pressure generated during contraction of the ventricles. -When the ventricles relax, blood pressure built up in the aorta closes the ... valves and prevents significant backflow.

atrioventricular valve

The Mammalian heart An .... lies between each atrium and ventricle (right AV valve = tricuspid valve; left AV valve = bicuspid or mitral valve) -The ... valves are anchored by strong fibers the CHORDAE TENDINEAE, to PAPILLARY MUSCLES, that prevent them from turning inside out. -pressure generated by the powerful contraction of the ventricles closes the ... valves, keeping blood from flowing back into the atria.

Double Circulation

The cardiovascular systems of amphibians, reptiles (including birds), and mammals have two circuits, an arrangement called ... -The pumps for the two circuits are combined into a single heart, which simplifies coordination of the pumping cycles. - One pump, the right side of the heart, delivers oxygen-poor blood to the capillary beds of the gas exchange tissues (lungs/skin), where there is a net movement of oxygen into the blood and of carbon dioxide out of the blood. This type of circulation is called a PULMONARY CIRCUIT if the capillary beds involved are all in the lungs, as in reptiles and mammals. -It is called a PULMOCUTANEOUS CIRCUIT if it includes capillaries in both the lungs and the skin, as in many amphibians. -After the oxygen-enriched blood leaves the gas exchange tissues, it enters the other pump, the left side of the heart. -Contraction of the heart propels this blood to capillary beds in organs and tissues throughout the body, the SYSTEMIC CIRCUIT. -Following the exchange of oxygen and carbon dioxide, as well as nutrients and waste products, the now oxygen-poor blood returns to the heart, completing the systemic circuit. -.... provides a vigorous flow of blood to the brain, muscles, and other organs because the left side of the heart repressurizes the blood (by pumping it) after it passes through the capillary beds of the lungs or skin. -This contrasts sharply with single circulation, in which blood flows under reduced pressure directly from the gas exchange organs to other body tissues.

ventricles

The chambers responsible for pumping blood out of the heart are called ....

atria

The chambers that receive blood entering the heart are called ... (singular, atrium).

Vertebrates

The closed circulatory system of humans and other vertebrates is often called the CARDIOVASCULAR SYSTEM.

Function of the Circulatory System

The heart contracts and relaxes in a rhythmic cycle. When it contracts, it pumps blood; when it relaxes, its chambers fill with blood.

repolarization

The wave associated with ... of the atria (immediately preceding atrial diastole) is hidden by the much larger QRS complex. In addition to the wave components of the ECG, there are also intervals and segments.

lab

Your lab team will examine ECG components of cardiac cycles and measure amplitudes (measured in millivolts; mV) and durations (measured in seconds; s) of the ECG components and investigate the effects of body position, breathing and physical activity on rate and rhythm changes in the ECG. -How will the cardiac cycle be affected by the activities described above? using the word "because" to explain how increased physical activity will affect the cardiac cycle. And predict results of your ECG experiment using an "if/then" statement.

the conducting system

a) An electrical impulse travels from the sinoatrial node to the walls of the atria, causing them to contract b) The impulse reaches the atrioventricular node, which delayed it by about 0.1 second c) Bundle branches carry signals from the atrioventricular node to the heart apex d) The signal spreads through the ventricle walls, causing them to contract

blood

blood is made up of 4 things essentially. We got red blood cells. Those are carrying the oxygen around your body. We also have the plasma. plasma is going to be the liquid portion. it has a lot of nutrients in it but its also going to carry that carbon dioxide as bicarbonate. -we have white blood cells that are going to fight infection -then finally we have platelets these are important in blood clotting so if you get cut the platelets will form almost a lattice across that cut and eventually you'll have the formation of a scab. -in a tube red blood cells are going to be down at the bottom, and then were going to have the other things continue throughout that whole of the blood, like plasma.

Arteries

carry blood away from the heart to organs throughout the body -Within organs, arteries branch into arterioles, small vessels that convey blood to the capillaries.

sequence

heart → arteries → arterioles → capillaries → venules → veins → heart

hydra

in hydra and other cnidarians, nutrients circulate through the gastrovascular cavity and come in contact with the inner layer of body cells. Nutrients diffuse the short distance to the outer layer of cells

planarian flatworms

in planarian flatworms, the branched gastrovascular cavity allows nutrients to come within close proximity of most body cells

humans

in us we put our blood inside blood vessels and then the interstitial fluid is going to be everywhere else inside our body. and so we keep those separate -CLOSED CIRCULATORY SYSTEM

gastrovascular cavity

invertebrates In cnidarians and flatworms with a ... (functions in both digestion and the distribution of substances around the body), fluid directly bathes both the inner and outer tissue layers, facilitating exchange of gases (O2 and CO2) and cellular waste. -Only the cells lining the gastrovascular cavity have direct access to nutrients released by digestion. -However, because the body wall is only a few cells thick, nutrients diffuse only a short distance to reach the cells of the outer tissue layer.

circulatory system

is important it moves oxygen around your body. It moves carbon dioxide out of your body and it move nutrients to the cells in your body. -we also need it to keep beating

heart attack

now your heart continues to beat your whole life but its a muscle and it needs oxygen and it needs nutrients as well. So how does it get those? Well we have what are called coronary/carotid arteries that are on the outside of your heart. And those carotid arteries are going to serve all of the muscle inside the heart. And if we ever have a blockage inside one of those what's that going to do? Well we're not going to get nutrients and oxygen to that part of the body and so that part of the body is going to die. Its not going to be able to do its job. -And so what is a heart attack? A heart attack is simply when you have blockage in the vessels that serve the heart. And so the heart muscle can die. And that's why its super important that we take care of our heart. We keep our vessels very clean because we need our heart to beat our whole life.

land

on ... you loose quite a bit of that pressure as you go to the gills or if on land as you go to the lungs, and so it simply isn't a system that that works -this is why on land we have a 3 chambered heart -so things like this a breaded dragon have a 3 chambered heart -What we have now is 2 loops -and so we have one loop that goes to the lungs and then it comes back to the heart -and then we have another loop that goes to the rest of the body -and so that deals with that pressure issue -one thing that is interesting is that instead of having red and blue blood we now have this purple blood. This means we are getting a mixing of the blood. we are having a mixing of the oxygenated blood in the red and the deoxygenated blood in the blue. And that's only because we have 3 chambers in the heart -once we become endothermic this is no longer efficient

circulatory system

plays a central role in the maintenance of homeostasis by linking exchange surfaces (e.g. digestive tract, lungs, kidneys) with cells throughout the body allowing the body to effectively utilize environmental materials (e.g. food and oxygen) and eliminate wastes (e.g. carbon dioxide, nitrogenous wastes, hormones).

Mammalian Circulation

pulmonary circuit begins when the right ventricle contracts to pump blood to the lungs via the pulmonary arteries. -As the blood flows through capillary beds in the left and right lungs, it loads oxygen and unloads carbon dioxide. -Oxygen-rich blood returns from the lungs via the pulmonary veins to the left atrium of the heart. -Next, the oxygen-rich blood flows into the left ventricle, which pumps the oxygen-rich blood out to all body tissues except the lungs through the systemic circuit. -Blood leaves the left ventricle via the aorta, which conveys blood to arteries throughout the body. -The first branches leading from the aorta are the coronary arteries, which supply blood to the heart muscle itself. Other branches lead to capillary beds in the head and arms. -The aorta then descends into the abdomen, supplying oxygen-rich blood to arteries leading to capillary beds in the abdominal organs, legs and tail (if present). -Capillaries rejoin, forming venules, which convey blood to veins. -Oxygen-poor blood from the head, neck, and forelimbs is channeled into a large vein, the superior/cranial/anterior vena cava -Another large vein, the inferior/caudal/posterior vena cava, drains oxygen-poor blood from the trunk and hind limbs. -The two vena cavae empty their blood into the right atrium, from which the oxygen-poor blood flows into the right ventricle.

sinoatrial node

so basically you have this sinoatrial node or the SA node, and what its going to do is this is where the heart contraction is going to start. so basically what's going to happen is you're going to start the contraction at the top of the heart and its going to squeeze the atrium shut, so were going to get a flow of electricity in contraction, pushing it down. But then what happens is that electrical signal will go all the way down here to the apex of the heart and then were going to get it flowing in the other direction. so now we have that flow going up to the ventricle because we want to move that blood remember from the atrium to the ventricle. And then the ventricle either out to the pulmonary artery or out to the aorta. So it goes to rest of the body. so that's an electrical signal that does that.

the loop

so what doe blood do? Blood follows a ... -And so its going to start at the heart. its going to move throughout rest of the body in arteries, arterioles eventually down to capillaries and then come back again. And so it keeps moving around your body -its moving nutrients and its moving carbon dioxide out and its moving oxygen to the parts of your body that need it.

sympathetic division

the ... (fight-or-flight response) speeds up the pacemaker, -For example, when you stand up and start walking, the ... increases your heart rate, an adaptation that enables your circulatory system to provide the additional oxygen needed by the muscles that are powering your activity

parasympathetic division

the ... (rest-or-digest response) slows the pacemaker down -for example when you stand up and start walking, the sympathetic division increases your heart rate, an adaptation that enables your circulatory system to provide the additional oxygen needed by the muscles that are powering your activity. If you then sit down and relax, the .... decreases your heart rate, an adaptation that conserves energy.

T wave

the ... results from ventricular REPOLARIZATION, which occurs immediately before ventricular diastole.

arteries and veins

the arteries differ from the veins in a few ways 1) they're not going to be as strong, theres not as much connective tissue around it. But they also have valves in them because once that blood has gone all the way down to the bottom like to your feet it has to get its way all the way back to your heart. we've lost a lot of that pressure and so as the blood flows up, we have valves that are found in the veins and so it will actually move up And then its can't go back down again because something closes. and so its going to work its way back up the heart. And that's why if you're on bed rest for example its important that we move your body around because as you move muscles you're actually helping to return that blood back to your heart.

getting started

the plastomount hearts have been artificially colored so that deoxygenated portions are blue, and oxygenated portions are red. Fish (all blue, 1 section) , Amphibian (3 blue, 1 Red), Reptile (2 blue, 2 red) , Bird (2 blue, 2 red), and Mammal (2 blue, 2 red) (order from left to right)

Circulation

the transport of fluid around a body, connects the cells of multicellular organisms even though they are separated physically, allowing these cells to exchange materials between themselves and with the environment. -animals are composed of many cells, each cell has to have access to all neededsubstances (e.g. oxygen, nutrients) in a suitable aqueousenvironment (either inside or outside of the animal'sbody)

veins

the vessels that carry blood back to the heart. -Arteries and veins are distinguished by the direction in which they carry blood, not by the oxygen content or other characteristics of the blood they contain.

blood vessels

they go from the arteries to the arterioles then its going to go to the capillaries and then its going to go back to the venules and then its going to go back to the veins. and so most of the pressure is being handled by the arteries and the veins. -So the red is going going to be the arteries moving away from the heart -and the blue is going to be the veins coming back -blood is red and its always red. -veins are blue because that's the connective tissue in those veins but its not the blood.