 The circulatory system carries blood and dissolved substances to and from different places in the body.  The Heart has the job of pumping these things around the body.  The Heart pumps blood and substances around the body in tubes called blood vessels.  The Heart and blood vessels together make up the Circulatory System. What is the circulatory system?

Lungs Body cells Our circulatory system is a double circulatory system. This means it has two parts parts. the right side of the system deals with deoxygenated blood. the left side of the system deals with oxygenated blood.

Two circulatory paths Pulmonary Systemic

The double pump

The Heart These are arteries. They carry blood away from the heart. This is a vein. It brings blood from the body, except the lungs. Coronary arteries, the hearts own blood supply The heart has four chambers 2 atria 2 ventricles now lets look inside the heart

The Heart Left Ventricle Left Atrium Right Atrium Right Ventricle valve Vein from Lungs Artery to Head and BodyArtery to Lungs Vein from Head and Body valve

II.Circulatory System Components Heart - divided into four chambers –right atrium, right ventricle, left atrium, left ventricle

Heart Chambers and Valves

How does the Heart work? blood from the body blood from the lungs The heart beat begins when the heart muscles relax and blood flows into the atria. STEP ONE

The atria then contract and the valves open to allow blood into the ventricles. How does the Heart work? STEP TWO

How does the Heart work? The valves close to stop blood flowing backwards. The ventricles contract forcing the blood to leave the heart. At the same time, the atria are relaxing and once again filling with blood. The cycle then repeats itself. STEP THREE

Right Heart Chambers: Pulmonary Circuit Right Atrium (forms most of posterior of heart) –Receives O 2 -poor blood from body via IVC, SVC, Right Ventricle –Receives O 2 -poor blood from right atrium through tricuspid valve –Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk

Left Heart Chambers: Systemic Circuit Left Atrium –Receives O 2 -rich blood from 4 Pulmonary Veins Left Ventricle (forms apex of heart) –Receives blood from Left Atrium via bicuspid valve –Pumps blood into aorta via Aortic Semilunar Valve to body

Heart Valves: Lub*-Dub** *Tricuspid Valve: Right AV valve –3 Cusps (flaps) made of endocardium and CT –Flow of blood pushes cusps open –When ventricle in diastole (relaxed), cusps hang limp in ventricle –Ventricular contraction increases pressure and forces cusps closed *Bicuspid (Mitral) Valve: Left AV valve –2 cusps anchored in Lft. Ventricle by chordae tendinae –Functions same as Rt. AV valve **Semilunar valves: prevents backflow in large arteries –Pulmonary Semilunar Valve: Rt Ventricle and Pulmonary Trunk –Aortic Semilunar Valve: Left Ventricle and Aorta

blood from the heart gets around the body through blood vessels There are 3 types of blood vessels a. ARTERY b. VEIN c. CAPILLARY

Three types of blood vessels –arteries carry blood away thicker walls to withstand the pressure of blood being pumped from heart –veins - toward heart lower pressure one-way valves to prevent blood from flowing backwards away from heart –capillaries tiny links b/w arteries and veins where oxygen and nutrients diffuse to body tissues smallest of blood vessels, are only visible by microscope ten capillaries lying side by side are barely as thick as a human hair.

The ARTERY thick muscle and elastic fibres A rteries carry blood A way from the heart. the elastic fibres allow the artery to stretch under pressure the thick muscle can contract to push the blood along.

The VEIN Veins carry blood towards the heart. thin muscle and elastic fibres veins have valves which act to stop the blood from going in the wrong direction. body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.

The CAPILLARY Capillaries link Arteries with Veins the wall of a capillary is only one cell thick they exchange materials between the blood and other body cells. The exchange of materials between the blood and the body can only occur through capillaries.

Arteries, veins, and capillaries - divided into two systems: –Systemic - carries oxygenated blood from heart to all tissues in body except lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to heart. oxygen-rich blood ejected under high pressure out of heart's main pumping chamber (L. ventricle) through largest artery (aorta) smaller arteries branch off from aorta to various parts of the body smaller arteries in turn branch out into even smaller arteries (arterioles) arterioles become progressively smaller eventually forming capillaries - blood pressure is greatly reduced

interstitial fluid fills the gaps between the cells of tissues or organs –dissolved oxygen and nutrients then enter the cells from interstitial fluid by diffusion –carbon dioxide and other wastes leave the cell via interstitial fluid, cross capillary walls, and enter blood. after delivering oxygen to tissues and absorbing wastes, deoxygenated blood in capillaries then starts the return trip to heart

capillaries merge to form tiny veins, called venules venules join together to form progressively larger veins veins converge into two large veins: –inferior vena cava-brings blood from the lower half of body –superior vena cava-brings blood from upper half – Both join at the right atrium of heart

FYI –Varicose Veins pressure is dissipated in arterioles and capillaries blood in veins flows back to heart at very low pressure, often running uphill when a person is standing Flow against gravity allowed by one-way valves –several centimeters apart in veins Veins with defective valves (allow the blood to flow backward) become enlarged or dilated to form varicose veins

Varicose veins

–Pulmonary Circulation deoxygenated blood returning from organs and tissues travel from R. atrium to R. ventricle. pushed through pulmonary artery to lung pulmonary artery divides forming pulmonary capillary region microscopic vessels pass adjacent to alveoli (air sacs) - gases are exchanged across thin membrane oxygen crosses membrane into blood while carbon dioxide leaves blood through same membrane newly oxygenated blood then flows into pulmonary veins and is collected by L. atrium of the heart (collecting pool for L.ventricle) contraction of L. ventricle sends blood into aorta completing circulatory loop

L. LUNG R. LUNG HEART AORTIC ARCH SUP. VENA CAVA INF. VENA CAVA AORTA PUL. ARTERY PUL. VEINS

Artery/Vein differences Arteries (aa.)Veins (vv.) Direction of flow Blood Away from Heart Blood to Heart PressureHigherLower WallsTHICKER: Tunica media thicker than tunica externa THINNER: Tunica externa thicker than tunica media LumenSmallerLarger ValvesNo valvesValves (see next)

what’s in red blood cells white blood cells platelets plasma carbon dioxide digested food waste (urea) hormones oxygen

The Blood plasma red blood cell white blood cell platelets

Red Blood Cells contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it. can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries. a biconcave disc that is round and flat without a nucleus

White Blood Cells there are many different types and all contain a big nucleus. the two main ones are the lymphocytes and the macrophages. some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them. other lymphocytes make antitoxins to break down poisons. macrophages ‘eat’ and digest micro- organisms. `

Platelets Platelets are bits of cell broken off larger cells. Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.

Plasma A straw- coloured liquid that carries the cells and the platelets which help blood clot. carbon dioxide glucose amino acids proteins minerals vitamins hormones waste materials like urea. It also contains useful things like;

Heart Chambers and Valves