The Heart

4 distinct circuits for the flow of blood Pulmonary Circulation – heart to lungs and back Systemic Circulation – heart to entire body and back Renal Circulation – blood flow through kidneys Hepatic-Portal Circulation – blood flow through liver and digestive system Transporting O 2 and other stuff (The Circulatory System)

You must be able to recognise all the major features of the heart and appreciate their relationships. A science picture from grade 5 - any mistakes? Can you recognise all of these structures? Can you relate what you see in diagrams to what you see in real life?

The Heart A.Heart Facts 1.Size of human fist 2.Located in center of chest under the sternum. 3.Outside covered with a protective sac called the pericardium which helps lubricate the surface of the moving heart.

B.Structure 1.Has four chambers R. atrium R. ventricle L. atrium L. ventricle

2.Divided into two sides by the septum. Septum

3.Each side has 2 chambers a.Atrium - thin walled on top b.Ventricle - thick walled on bottom

4.The heart muscle is nourished by its own series of coronary arteries, capillaries and veins. Coronary artery Coronary vein

5.The heart contains 4 valves that ensure blood flows in one direction. a.Between the atria and ventricles are the atrioventricular valves Tricuspid valve Bicuspid valve

b.There are two semilunar valves at the exit of the ventricles. Pulmonary valve Aortic valve

6.Blood flow summary a.O 2 poor and CO 2 rich blood from the body enters the R. atrium from the vena cava Posterior Vena cava Superior Vena cava

b.Blood pumped to the R. ventricle through the tricuspid valve. Tricuspid valve

c.R. ventricle pumps blood through pulmonary valve to L and R pulmonary arteries. Pulmonary valve Pulmonary arteries

d.Blood travels to lung capillaries where O 2 is picked up and CO 2 dropped off.

e.Blood enters the L. atrium through 4 pulmonary veins. Pulmonary veins

f.Blood pumped into L. ventricle through bicuspid valve. Bicuspid valve

g.Blood is pumped from the L. ventricle through the aortic valve into the aorta. aorta aortic valve Aorta

How Blood Flows: The Heart

You must be able to follow the path of blood flow through the heart without any problem.

- The two atria work together to collect blood (VEINS) and then pump it into the ventricles. - The two ventricles work together by collecting blood from the atria and then pumping it AWAY from the heart. (ARTERIES)

You must be able to follow the path of blood flow through the heart without any problem. - a right heart pumping blood to the lungs - a left heart pumping blood around the body Two separate circuits - The two atria work together to collect blood (VEINS) and then pump it into the ventricles. - The two ventricles work together by collecting blood from the atria and then pumping it AWAY from the heart. (ARTERIES)

You must be able to follow the path of blood flow through the heart without any problem. Blood flow AFTER birth Blood flow BEFORE birth Before birth, bypass the lungs: - ductus arteriosus - foramen ovale -‘best blood’ goes to liver, heart and brain - blood flows from high to low pressure

C.Heart Valves 1.Ensure one way flow of blood through the heart. 2.AV valves are anchored with cordae tendonae.

3.Heart sounds are produced by closing valves. a.Described as “lub dub” b.Lub = AV Valves closing during contraction (systole) c.Dub = Semilunar valves closing during relaxation (diastole)

D.Measuring Heart Rate 1.Pulse or heart rate = contractions per minute. 2.Your heart rate changes in response to: a.Exercise – muscles demand food and O 2 and generate more waste. b.Stress or excitement – body perceives need for fight or flight. c.Chemicals – nicotine, caffeine directly stimulate the nerves that control the heart. Heart rate 1 Heart rate 2

Coordination of the Beating Heart cells naturally beat slowly if ATP is present If there was no coordination, the heart cells would all beat randomly (fibrillation) Coordinated beating occurs because a group of cells (the pacemaker cells) send nerve impulses to the other cells stimulating them to beat at the right time Atria beat from top down, pause, Ventricals beat from bottom up

The heart muscle is self-stimulating because of the action of the sinoatrial node, a collection of nerves in the right atrium.

The SA node acts as a pacemaker and sends signals to the atria and atrioventricular node in the septum of the heart.

The AV node distributes the nerve impulse via nerves of the Bundle of His and then Purkinje fibres to the ventricles.

The heart contracts from top to bottom; atria, followed by ventricles.heart contracts

Heart rate can be altered by two nerves coming from the medulla oblongata of the brain to the SA node. i.Vagus nerve – more impulses slows heart rate. Part of the parasympathetic nervous system. ii.Sympathetic Nerve – more impulses increase heart rate. Part of the sympathetic nervous system.

Heart rate can also be increased by the release of epinephrine (adrenaline) by the adrenal gland into the blood.

Assignment: Create a valentine Include Diagram of heart Structure of heart (labeled) Colour red for oxygenated and blue for deoxygenated Direction of blood flow How the heart beats Catchy phrase describing a function of the heat