Starter Questions What is the difference between circulatory systems between unicellular and multicellular organisms. How many chambers does the heart have and identify if they have oxygenated or deoxygenated blood. How is an impulse transmitted across the heart?

The Circulatory System Introduction Chapter 37.1

Circulatory System Single cells can get nutrients from their environment and get rid of wastes by simple diffusion A circulatory system is only needed in larger organisms with multiple cells  Body cells must be bathed in fluid to transport nutrients and wastes

Types of Circulatory Systems Open Circulatory System –No vessels  Blood just floats in the body cavities Closed Circulatory System –Blood flows in a system of vessels

Human Circulatory System  The human circulatory system consists of the: 1. heart 2.a series of blood vessels 3.blood

The Heart Structure Composed of cardiac muscle Located near the center of your chest Pericardium: protective sac that encloses the heart Myocardium –thick middle muscle layer of the heart –Pumps blood through the c.s. Septum –divides the left and right side of the heart –prevents the mixing of oxygen-poor and oxygen-rich blood

The Heart Circulation through the body Two separate pumps –Pulmonary Circulation the right side of the heart pumps blood from the heart to the lungs and back again leaves deoxygenated, returns oxygenated –Systemic Circulation the left side of the heart pumps blood from the heart to the body and back again leaves oxygenated, returns deoxygenated

w.echalk. co.uk/Sci ence/Biol ogy/heart/ heart.htm

The Heart Both pumps have an atrium and a ventricle –Atrium – upper chamber (  receives blood) –Ventricle – lower chamber (  pumps out blood)

Pulmonary Circulation Right side of heart (right atria, right ventricle) –Pumps to and from lungs  oxygen poor blood to lungs  oxygen rich blood to heart –Includes tricuspid valve, pulmonary valve, pulmonary artery, pulmonary vein

Systemic Circulation Left side of heart (left atria, left ventricle) –Pumps blood to and from body  oxygen rich blood leaves the heart  oxygen poor blood comes from the body –Includes bicuspid valve, aortic valve, aorta, and vena cava

Inferior Vena Cava Vein that brings oxygen-poor blood from the lower part of the body to the right atrium Tricuspid Valve Prevents blood from flowing back into the right atrium after it has entered the right ventricle Pulmonary Valve Prevents blood from flowing back into the right ventricle after it has entered the pulmonary artery Pulmonary Veins Bring oxygen-rich blood from each of the lungs to the left atrium Superior Vena Cava Large vein that brings oxygen-poor blood from the upper part of the body to the right atrium Aorta Brings oxygen-rich blood from the left ventricle to the rest of the body Pulmonary Arteries Bring oxygen-poor blood to the lungs Aortic Valve Prevents blood from flowing back into the left ventricle after it has entered the aorta Mitral Valve Prevents blood from flowing back into the left atrium after it has entered the left ventricle Right Ventricle Right Atrium Left Ventricle Septum Left Atrium

Blood Flow Goes from atria to ventricles to blood vessels Valves flaps of connective tissue that prevent the back flow of blood guarantees one-way flow increase pumping efficiency of the heart 4 valves in the heart Tricuspid valve– found in between the right atrium and right ventricle Pulmonary valve - found in between the right ventricle and pulmonary artery Mitral (bicuspid) valve - found in between the left atrium and left ventricle Aortic valve - found in between the left ventricle and the aorta

Heart Control The heartbeat is actually two-different muscular contractions –1 st – contraction of the atria – SA node  started at the pacemaker in the right atria –2 nd – contraction of the ventricles – AV node

The Heartbeat

The EKG Measures the electricity passing through the heart at any specific time Can be used to diagnose heart conditions Each part of the EKG shows what is happening in the heart

EKG Parts P Wave  contraction of the atria QRS Complex  contraction of the ventricles T Wave  resetting of the heart

The EKG

 force that blood exerts on the arteries when the heart contracts Measures using a device called a sphygmomanometer Listen for the flow of blood through arteries –Top number is called systolic pressure  pressure exerted by contracting ventricles –Bottom number is called diastolic pressure  pressure exerted by resting ventricles Normal is 120/80 Blood Pressure

Regulated in two ways: –When stressed, neurotransmitters relax muscles around arteries Lowers blood pressure Controlled by autonomic nervous system –Hormones control retention in the blood Remove water to lower blood pressure