The Cardiovascular System The cardiovascular system is composed of Blood Blood vessels The blood vessels transport blood throughout the body Heart The heart is a muscular pump that pumps blood

The Blood Vessels Conduct Blood in Continuous Loops Blood passes through the following loop of vessels moving away from the heart Arteries Arterioles Capillaries Venules Veins Blood returns to the heart from the veins

The Blood Vessels Conduct Blood in Continuous Loops Arteries- carry blood away from the heart Contain the thickest wall of the blood vessels Blood is usually oxygenated Arterioles-small arteries; carry blood to capillaries

The Blood Vessels Conduct Blood in Continuous Loops Venule- small veins that carry blood away from the capillary Vein- thinner walls than arteries; contain valves for one-way flow of blood. Carry blood to the heart Blood is usually deoxygentated

Valves & muscles moves blood in veins Valve closed Valve open Muscle contraction squeezes the vein, pushing blood through the open valve toward the heart. Skeletal muscles relax, and blood fills the valves and closes them. Valve closed (b) Relaxed calf muscles Contracted calf muscles Figure 12.6b

The Blood Vessels Conduct Blood in Continuous Loops Capillary- thinnest walls of all blood vessels Capillary-has walls that are one cell thick Site of exchange between the body and the blood

The Blood Vessels Conduct Blood in Continuous Loops Most materials simply diffuse across the capillary wall into the cells by the force of both blood pressure and osmotic pressure Figure 12.3

Blood Vessels Capillary-has the greatest total cross-sectional area More capillaries in the body than arteries or veins Figure 12.5

The Heart is a Muscular Pump The heart is located in the Thorax (chest ) Pericardium- sac around the heart Pericardial cavity is filled with fluid that cushions the heart

The Heart is a Muscular Pump Heart wall has 3 layers: Epicardium- outer layer Myocardium- thick middle layer made of cardiac muscle Endocardium- innermost layer Figure 12.7a

The Heart is a Muscular Pump The heart has 2 sides Right side pumps blood to the lungs Left side pumps blood to the body

The Heart is a double Pump The right side of the heart Contains blood low in oxygen (deoxygenated) Pumps blood to the lungs The left side of the heart Contains blood rich in oxygen Pumps blood out to the body

The Heart is a Muscular Pump Heart has 4 chambers: Atria- upper chambers; Left & right atrium Ventricles- lower chambers; Left & right ventricles

The Heart Valves 4 heart valves 2 Atrioventricular ( AV ) Valves 2 semilunar valves Closing of heart valves produce lub-dup heart sound

The Heart Valves AV valves - Separate the atria from ventricles Both AV valves contain strings called chordae tendinae that keep the valve from turning inside out. Tricuspid valve- separate right atrium from the right ventricle (3 flaps) Bicuspid valve- separate left atrium from the left ventricle (2 flaps)

The Heart Valves Keep blood from flowing backwards Semilunar valves - Separate the ventricles from the attached blood vessels Keep blood from flowing backwards Pulmonary semilunar valve- lead into the pulmonary artery Aortic Semilunar valve- lead into the aorta

Pulmonary circulation vs Systemic circulation Pulmonary Circuit- blood flow from the right side of the heart to the lungs and back to the left side of the heart

Pulmonary circulation vs Systemic circulation Systemic Circuit- blood flow from the left side of the heart to the body and back to the right side of the heart

Pulmonary circulation vs Systemic circulation

The Heart is a Muscular Pump The heart muscle is nourished by coronary circulation Coronary arteries –supply the heart with oxygenated blood Coronary veins- drain the heart

CARDIAC CYCLE = .85 SEC. Systole= contract Diastole= relax Time ATRIA VENTRICLES 0.15 sec SYSTOLE DIASTOLE 0.30 sec 0.40 sec Systole= contract Diastole= relax

The cardiac cycle Figure 12.11

Contraction of the heart Sinoatrial Node- commonly called the pacemaker Located in the wall of the upper right atrium It generates it’s own Impulses due to it’s natural ability to leak sodium ions

Contraction of the heart When the Sa node fires an electrical stimulus is sent across both upper chambers causing them to contract Av node (located in the interatrial septum) picks up the stimulus and passes it to the AV bundle and purkinje fibers in the wall of the ventricles Then the ventricles contract

Contraction Of The Heart

Regulation of Heart Beat A combination of nervous and endocrine signals control the strength and rate of contraction of the heart

Electrocardiogram (ECG/EKG) a recording of the electrical signals (voltage changes) across the myocardium Abnormal patterns can indicate heart problems

Electrocardiogram (ECG/EKG) A typical ECG/EKG consists of three waves P wave QRS wave T wave

Electrocardiogram (ECG/EKG) P wave- atrial depolarization & contraction QRS wave- ventricular depolarization & contraction T wave- recovery of the ventricles

Blood Pressure Sphygmomanometer – an instrument used to measure blood pressure Can provide early identification of hypertension, or high blood pressure, the silent killer

Blood Pressure Blood pressure Highest (systolic) when the ventricles contract, sending blood into the arteries Lowest (diastolic) when the heart relaxes between beats

Blood Pressure 120/80mmHg is normal blood pressure 120- pressure in the blood vessel when the ventricles contract 80- pressure in the blood vessel when the ventricles relax Figure 12.14 (2 of 2)

Cardiovascular Disease Atheroscloerosis A narrowing of the arteries due to fatty deposits and thickening of the wall Can lead to heart attack or stroke When this occurs in the arteries of the heart muscle, it is called coronary artery disease

Cardiovascular Disease (Angioplasty) Angioplasty- blocked artery is opened by inserting a balloon.

Cardiovascular Disease (Coronary bypass) Blood is rerouted around closed vessel by using a vein from the leg Figure 12.18

Cardiovascular Disease Figure 12.19

Cardiovascular Disease Myocardial Infarction (heart attack) - part of the myocardium dies due to the lack of oxygen. Heart failure Condition in which the heart becomes an inefficient pump Leads to shortness of breath, fatigue, and fluid accumulation

Lymphatic System Components of the lymphatic system Lymph Fluid identical to interstitial fluid Lymphatic vessels Vessels through which lymph flows Have one-way valves to prevent backflow Lymphoid tissues and organs

Lymphatic System Functions of the lymphatic system Return excess interstitial fluid to the bloodstream Transport products of fat digestion from the small intestine to the bloodstream Defend the body against disease-causing organisms and abnormal cells

Lymphatic System Elephantiasis A condition in which parasites block lymphatic vessels, preventing the return of fluid to blood Results in massive swelling, darkening, and thickening of the skin in the affected area

Lymphatic System Lymphatic capillaries Extra fluid enters these microscopic tubules Differ from blood capillaries End blindly More permeable Drain into larger lymphatic vessels Lymph eventually enters ducts that join with large veins at the base of the neck

Lymphatic System Lymph nodes Bean-shaped structures Filter lymph as it flows through them Contain macrophages and lymphocytes that actively defend against disease-causing organisms

Lymphatic System Lymphoid organs include Tonsils Thymus gland Spleen Peyer’s patches (nodules along the small intestine) Red bone marrow