Unit 5 – Anatomy & Physiology Circulatory System Sophie Bevan

Objectives By the end of the lesson you will be able to:- Identify the gross structures of the CV system; Describe, in detail, the flow of blood around the body: Discuss the structure & function of different types of blood vessels.

The circulatory system is also known as the cardiovascular system. It consists of… 3. The Heart1. Blood2. Blood Vessels The three main types of blood vessels are arteries, veins and capillaries. The Circulatory System

Blood does the job of a non-stop courier service - it collects chemicals from one part of the body and delivers them to other parts, for use or disposal. What is Blood made of? If blood is spun in a centrifuge it will separate into 4 parts… What does Blood do? Plasma is a straw-coloured liquid. It is mostly water with dissolved nutrients, salts, hormones and proteins. White blood cells help to fight infection. Platelets are cell fragments. Blood spinning in a centrifuge. Red blood cells make up about 45% of the total volume of the blood

Blood Structure A photomicrograph of a blood smear showing the appearance of blood as seen with the light microscope (1000 x Magnification). A photomicrograph of a blood smear showing the appearance of blood as seen with the light microscope (1000 x Magnification). White blood cells Plasma Platelets Red blood cells White blood cells Plasma Platelets Red blood cells

PLASMA This is the liquid part of blood - it is straw coloured. A.Carbon dioxide away from cells to the lungs for removal from the body. B.Glucose from the small intestine to the cells for use in energy production. C.Nutrients from the small intestine to the cells for use in growth and repair. D.Other waste products away from cells for removal from the body, e.g. urea and heat when the body is hot. Its main role is the transport of: Function

These have a nucleus (control centre) and vary in shape and size. White Blood Cells A.Engulfing any invading microbes, defending the body from disease. B.Producing antibodies which help the body attack disease. Their main role is to protect the body from disease by: Function

These are tiny pieces of cell which have no nucleus. Platelets Clump together when blood vessels are damaged and help to clog a ‘meshwork’ of fibres which create a clot, to help stop bleeding. Their main role is to: Function

These have no nucleus and are very flexible so they can pass through the extremely tiny capillaries of the body. Red Blood Cells Their main role is to: A.Collect and carry oxygen to all the cells of the body so they can create energy. B.In order to do this, red blood cells contain Haemoglobin, which combines with oxygen to become Oxyhaemoglobin. Function

Red Blood Cells A scanning electron micrograph of human red blood cells showing the biconcave disc shape that gives these cells a large surface area to volume ratio. (x6000 Magnification). A scanning electron micrograph of human red blood cells showing the biconcave disc shape that gives these cells a large surface area to volume ratio. (x6000 Magnification).

Arteries Veins Capillaries Blood Vessels Lumen Muscle + elastic fibres Non-elastic fibres Muscle + elastic fibres Non-elastic fibres Muscle + elastic fibres Arteries carry blood away from the heart and have a thick, elastic, muscular wall. They stretch as blood is pumped in and the muscle wall contracts to force blood along. Veins have a relatively thinner and less muscular wall than arteries. The blood is under a lower pressure than in the arteries. Capillary walls are one cell thick. Exchange of nutrients and respiratory gases occurs across their surface.

Valve Closed Veins - Valves The blood pressure is lower in the veins than the arteries. Valve Open Muscle contraction and relaxation also squeezes the walls of the veins to help blood flow back towards the heart. To ensure that blood does not flow back towards the heart, between heartbeats, valves are present every few centimetres. The valves only allow blood to flow in one direction.

Arteries Veins The Major Blood Vessels

The Heart - Structure Right ventricle Septum (dividing wall) Tricuspid valve Vena cavae Aorta Right atrium Semilunar valves Pulmonary artery Pulmonary veins Left atrium Bicuspid valve Left ventricle Cardiac muscle

(A) (V) Lungs Heart Body How Blood is Pumped around the Body Blood flows around the body in a ‘figure of eight’ circuit, passing through the heart twice on each circuit. Blood travels away from the heart through arteries (A). Blood returns to the heart through veins (V). There are 2 separate ‘loops’ to the circuit: The top loop – carries blood from the heart to the lungs and back. The bottom loop – carries blood from the heart to all over the body and back. (A) (V)

The heart is divided into 2 parts. Each part is a pump, so the heart is a double pump. right side The right side pumps deoxygenated blood to the lungs to pick up oxygen. left side The left side pumps oxygenated blood to the rest of the body for use. From the lungs From the body To the lungs To the body How the Heart Pumps Blood

The Cardiac Cycle - How the Heart Beats Every time the heart beats it goes through a 3-part cycle: Stage 1 The top chambers (atria) relax and fill up with blood from the veins. Stage 2 The atria contract and the blood is forced into the relaxing bottom chambers (ventricles). Stage 3 The ventricles contract and the blood is forced out of the heart into the arteries.

The Cardiac Cycle - How the Heart Beats

1. 1.Blood leaves the right side of the heart via the pulmonary artery and goes to the lungs where it is oxygenated It then travels back to the left side of the heart via the pulmonary vein. Pulmonary artery Pulmonary vein Body Heart Lungs Blood Flow around the Body – Top Loop

3. 3.The left side of the heart then pumps the oxygenated blood around the rest of the body for use, via the aorta Once the oxygen has been used, the blood becomes deoxygenated and returns to the right side of the heart via the vena cava. Vena Cava Aorta Blood Flow around the Body - Bottom Loop Body Heart Lungs

Circulatory System Functions - Transport All the cells of the body require energy in order to work properly, e.g. muscle cells would not be able to contract without a supply of oxygen and fuel. Blood from the heart to all the cells of the body, providing them with fuel and oxygen. Waste products away from all the cells of the body, including carbon dioxide and urea. It is a delivery service… The circulatory system is therefore the body’s ‘transport system’. It carries… …and a waste disposal unit!

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