Chapter 33: Circulatory and Respiratory Systems

Chapter 33.1: The Circulatory System

Functions of the Circulatory System Transports oxygen, nutrients, and body heat throughout the body Removes wastes from tissues Works with the immune system to protect against illness

Structures of the Circulatory System Heart Muscular pump that moves blood through the system Has special muscle tissue called myocardium - Divided into 4 chambers Upper chambers are the atria (single = atrium) Lower chambers are the ventricles Contains valves that separate the chambers from each other

Structures of the Circulatory System Blood Vessels Include arteries Carry blood away from the heart Have thick, elastic walls to help them withstand blood pressure from the heart’s pumping Include capillaries Are small vessels that allow diffusion of oxygen, nutrients, carbon dioxide, and waste

Structures of the Circulatory System Blood Vessels Include veins Carry blood back to the heart, against gravity Utilize skeletal muscle contractions to help push blood along Have thin walls and valves to prevent blood from flowing backwards

Flow of Blood Through the Heart Systemic Circulation Uses the left side of the heart Pumps oxygenated blood to the body Includes the coronary arteries that service the heart Pulmonary Circulation Uses the right side of the heart Pumps deoxygenated blood to the lungs

Flow of Blood Through the Heart Vena cava brings deoxygenated blood back to the heart Blood enters the right atrium Blood flows through the atrioventricular valves to the right ventricle Blood flows through the semilunar valves into the pulmonary arteries Pulmonary arteries take blood to the lungs

Flow of Blood Through the Heart Re-oxygenated blood flows back to the heart in the pulmonary veins Blood enters the left atrium Blood flows through the atrioventricular valves to the left ventricle Blood flows through the semilunar valves and exits the heart through the aorta

The Heartbeat The sinoatrial node (SA node, or pacemaker node) sends an electrical impulse over the atria Both atria contract, pushing blood into the ventricles, causing a “lub” sound The atrioventricular node (AV node) picks up the impulse from the SA node The AV node pauses for a millisecond, then sends the electrical impulse over the ventricles Both ventricles contract, pushing blood into blood vessels, causing a “dub” sound

Blood Pressure Is measured in systolic pressure Shows the pressure in the arteries when the ventricles contract - Is measured in diastolic pressure Shows the pressure in the arteries when the ventricles relax Is measured with a sphygmomanometer Written as systolic over diastolic pressure Average BP = 120/80