animal circulatory system

7/29/2019 Animal Circulatory System

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ANIMAL CIRCULATORY

SYSTEM


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FUNCTION

To carry digested food from the small intestine to

all areas in the body which need it.

To carry oxygen from the lungs to the rest of the

body. To aid in the disposal of all wastes from the body.

To distribute heat.

To fight diseases by using white blood cells tofight off infection.


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ANIMAL CIRCULATORY SYSTEM

An efficient circulatory system has:

1. a fluid, e.g., blood, to carry the materials to betransported;

2. a system of vessels to distribute the blood;

3. a pump to push the blood through the system;

4. exchange organs to carry out exchanges between theblood and external environment, e.g., lungs and intestine to add materials to the blood;

lungs and kidneys to remove materials from the blood.

5. The most crucial demand on the circulatory system is

the transport of oxygen and carbon dioxide to and from agas exchange organ:lungs or gills and the tissues.

6. All exchanges between blood and cells occur in the

capillaries.
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The Fish Heart

1. Blood collected from throughoutthe fish's body enters a thin-walledreceiving chamber, the atrium.

2. As the heart relaxes, the bloodpasses through a valve into the thick-walled, muscularventricle.

3. Contraction of the ventricle forcesthe blood into the capillary networksof the gills where gas exchangeoccurs.

4. The blood then passes on to thecapillary networks that supply the restof the body where exchanges with thetissues occur.

5. Then the blood returns to theatrium.

While obviously adequate to the fish's needs,

this is not a very efficient system. The pressure

generated by contraction of the ventricle is

almost entirely dissipated when the blood enters

the gills.


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Three Chambers: the Frog and Lizard


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The Frog HeartThe frog heart has 3 chambers: two atria and a single ventricle.

1. The atrium receives deoxygenated blood from the blood vessels (veins) that drain thevarious organs of the body.

2. The left atrium receives oxygenated blood from the lungs and skin (which also servesas a gas exchange organ in most amphibians).

3. Both atria empty into the single ventricle.

4. While this might appear to waste the opportunity to keep oxygenated anddeoxygenated bloods separate, the ventricle is divided into narrow chambers thatreduce the mixing of the two blood.

5. So when the ventricle contracts, oxygenated blood from the left atrium is sent, relatively pure, into the carotid

arteries taking blood to the head (and brain); deoxygenated blood from the right atrium is sent, relatively pure, to thepulmocutaneous arteries taking blood to the skin and lungs where fresh oxygencan be picked up.

Only the blood passing into the aortic arches has been thoroughly mixed, but evenso it contains enough oxygen to supply the needs of the rest of the body.

Note, that in contrast to the fish, both the gas exchange organs and the interior tissuesof the body get their blood under full pressure


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The Lizard Heart

1. Lizards have a muscularseptum which partiallydivides the ventricle.

2. When the ventricle contracts, the opening in the

septum closes and the ventricle is momentarily dividedinto two separate chambers.

3. This prevents mixing of the two bloods.

The left half of the ventricle pumps oxygenated blood (receivedfrom the left atrium) to the body.

The right half pumps deoxygenated blood (received from theright atrium) to the lungs.


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The Squid Hearts

This group of marineinvertebrates haveseparate pumps:

1. two gill hearts toforce blood underpressure to the gillsand

2. a systemic heart toforce blood underpressure to the rest ofthe body.
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MAMMALIAN

CIRCULATORYSYSTEM


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THE CARDIAC CYCLE

1) alternating periods ofcontraction (systole),during which the heart is

pumping blood, and2) relaxation (diastole),during which the heart'schambers are filling withblood.

An average adult has aheart rate of about 70beats per minute.

At this rate, a completecardiac cycle takesroughly 0.8 seconds to

complete.1) 0.1s is atrial systole,

2) followed by about0.3s of ventricularsystole,

3) followed by about0.4s of atrial andventricular diastole.


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Arteries: Carry blood away from the heart always. Have thick muscular walls

Have a pulse Deep under the skin Have no valves

Veins:

Carry blood to the heart. Have thin walls Do not have a pulse Near surface of the skin Have valves to stop back-flow of blood.

Capillaries: Are small blood vessels acting as veins and arteries. The walls of capillaries are only one cell thick so substances (Food

or cells) can easily get through them and into the blood or out.


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Composition of Blood

1. The blood is made up of different types ofcells and a liquid medium for which they are

transported.

2. The cells in the blood are Red Blood Cell

(Corpuscles), White Blood Cells and

Platelets.

3. Red Blood Corpuscles are technically not

cells at all, as they do not contain a nucleus.Their red colour is from a substance known as

haemoglobin.

4. Plasma is the liquid medium of blood.


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BLOOD CELL LINEAGE


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animal circulatory system

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