Chapter 15

The Cardiorespiratory System Includes function of the heart, blood vessels, circulation, and gas exchange, between the blood and atmosphere. Heart pumps blood through the body through pathways (arteries, veins, and capillaries) Blood is enriched with oxygen when it passes through the lungs As oxygen enters the bloodstream, carbon dioxide leaves it (respiration)

The Circulatory System Course taken by blood through the arteries, capillaries, and veins & back to heart Uses blood to transport dissolved materials throughout body Oxygen, carbon dioxide, nutrients, waste Picks up waste products of cell metabolism & takes to lungs and kidneys (to be expelled from body)

The Heart Two major circulations Each has its own pump Both pumps are incorporated into the heart Location Middle of chest, behind sternum, within ribcage Pericardial cavity Above diaphragm Structure Primarily a shell with four chambers inside

Heart Facts Adult human heart approx size of closed fist About 5 inches long and 3 ½ inches wide Weighs just less than 1 pound Beats about 100,000 times each day Pump about 8,000 gallons of blood through 12,000 miles of vessels each day Contracts and relaxes bpm

Structure of Heart Four cavities Atria Form curved top of heart Ventricles Meet at bottom of heart to form pointed base Points toward left side of chest

Structure of Heart Left Side Right Side One ventricle One atrium Mitral valve—connects left atrium to left ventricle One ventricle One atrium Tricuspid valve—connects right atrium to right ventricle Wall, septum, separates right and left sides

Aorta heart’s main artery carries blood away from heart to body’s cells Pulmonary artery artery that connects heart to lungs Two largest veins: Superior vena cava Inferior vena cava Structure of Heart

Heart Anatomy

Blood Flow Two sides of heart are anatomically and functionally separate pumping units Right side  pumps blood through pulmonary circulation Left side  pumps blood through systemic circulation

As heart contracts, it pushes blood though chambers and into the vessels Nerves connected to the heart regulate the speed of contractions Greater the activity, faster the heart will pump; faster heart pumps, more oxygen and nutrient are carried throughout body Blood Flow

Flow of Blood through Heart Superior/inferior vena cava Right atrium Tricuspid valve Right ventricle Semi-lunar valve Pulmonary artery Lungs s/hhw/hhw_pumping.html

Flow of Blood through Heart Back to heart via pulmonary vein Left atrium Bicuspid valve Left ventricle Semi-lunar valve Aorta Organs in the body

Heart’s Conduction System Heart’s electrical system Consisting of specialized cells within heart muscle that carry an electrical signal Regulates pumping of heart

Heart Muscle Pericardium Epicardium Myocardium Endocardium

Blood Only tissue that flows throughout body Carries oxygen & nutrients to all parts of body and transports waste products back to lungs, kidneys, and liver for disposal Essential part of immune system Crucial for fluid and temperature balance Hydraulic fluid for certain functions Highway for hormonal messages Composed of plasma and billions of cells

Plasma The yellowish, liquid part of blood River in which blood cells travel Makes up 55% of total volume Carries blood cells + Nutrients (sugars, amino acids, fats, salts, minerals) Waste products (CO2, lactic acid, urea) Antibodies Clotting proteins (called clotting factors) Chemical messengers (hormones) Proteins that help maintain body’s fluid balance

Blood—RBCs & Hemoglobin Red Blood Cells (erythrocytes) Highly specialized cells that have been “stripped” of everything, including nucleus Major job: transporting oxygen Percentage of RBCs in total blood volume called hematocrit Hemoglobin Special red-colored molecule that fills RBCs Picks up oxygen in areas where O2 is abundant and releases O2 in tissues where O2 concentration lowest

Blood—White Blood Cells 5 distinct kinds Neutrophils, monocytes, lymphocytes, eosinophils, basophils Able to change according to need and situation in body Can leave blood stream, sliding out through vessel walls & attacking invaders at site of infections

Blood—Platelets Fragments of much larger cell (megakaryocyte) which stays in bone marrow after it differentiates and matures from stem cell Platelets leave bone marrow & circulate throughout the body When stimulated by substance from damaged tissue, platelets release substance to help clot blood

Blood Vessels Hollow tubes running throughout the body 5 types Arteries Arterioles Veins Venules Capillaries Provide 2 measurements: Pulse Blood pressure

Arteries Blood vessels that carry blood from the heart to organs & cells Muscular walls that allow them to dilate or constrict Arterioles: very small arteries Largest artery=aorta Runs from chest into abdomen Receives blood directly from left ventricle

Veins Blood vessels that carry blood back to heart Thinner wall Contain numerous one-way valves (keep blood moving toward heart) Deep veins in LE surrounded by large muscle groups; compress the deep veins when muscles contract Contractions in extremities helps propel blood toward heart; increase venous return

Veins Largest vein=superior & inferior vena cava Bring blood from upper and lower body into right atrium Venules: smallest veins

Capillaries Tiny, microscopic blood vessels that connect arteries to veins Responsible for transferring oxygen and nutrients to cells Wall so thin that O2 passes from arterial blood through them into cells in organs/tissues Waste products (CO2) pass into capillaries to be carried back by veins to heart/lungs

Coronary Arteries The heart’s own system of blood vessels Located around heart muscle to provide blood and oxygen to all parts of heart Two primary coronary arteries  branch off into smaller vessels Right coronary artery: feeds right atrium & ventricle and bottom of left ventricle Left main coronary artery: supplies blood to rest of heart Left anterior descending Circumflex

Blood Pressure Heart pumps blood into arteries; surge of blood filling vessels creates pressure against vessel walls Pressure measured by 2 numbers: Systolic: highest pressure in heart correlates to ventricular contraction Average 120 mm/Hg Diastolic: lowest pressure in heart correlates to ventricular relaxation Average 80 mm/Hg Pulse pressure: difference between diastolic and systolic pressures

Pulse Rhythmical beating of heart Created by alternating expansion and contraction of artery as blood flows through 7 areas where pulse can be felt Brachial artery Common carotid artery Femoral artery Dorsalis pedis artery Popliteal artery Radial artery Temporal artery

Target Heart Rate Percentage of the maximum heart rate that is safe to reach during exercise AHA recommends 50-75% for average healthy person Calculated 220-age THR is sliding scale that decreases with age Tool for measuring cardiovascular exercise Maintain THR for min daily  health benefits

Flow of Blood through Heart

Can you label the heart?