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 cellsBody 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 HeartStructure• 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

http://www.echalk.co.uk/Science/Biology/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 CavaVein that brings oxygen-poor blood from the lower part of the body to the right atrium

Tricuspid ValvePrevents blood from flowing back into the right atrium after it has entered the right ventricle

Pulmonary ValvePrevents blood from flowing back into the right ventricle after it has entered the pulmonary artery

Pulmonary VeinsBring oxygen-rich blood from each of the lungs to the left atrium

Superior Vena CavaLarge vein that brings oxygen-poor blood from the upper part of the body to the right atrium

AortaBrings oxygen-rich blood from the left ventricle to the rest of the body

Pulmonary ArteriesBring oxygen-poor blood to the lungs

Aortic ValvePrevents blood from flowing back into the left ventricle after it has entered the aorta

Mitral ValvePrevents 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– 1st – contraction of the atria – SA node

started at the pacemaker in the right atria

– 2nd – 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

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