Chapter 15

The Cardiorespiratory SystemIncludes 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 SystemCourse taken by blood through the arteries,

capillaries, and veins & back to heartUses blood to transport dissolved materials

throughout bodyOxygen, carbon dioxide, nutrients, waste

Picks up waste products of cell metabolism & takes to lungs and kidneys (to be expelled from body)

The HeartTwo major circulations

Each has its own pumpBoth pumps are

incorporated into the heart

LocationMiddle of chest,

behind sternum, within ribcage

Pericardial cavityAbove diaphragm

Structure Primarily a shell with

four chambers inside

Heart FactsAdult human heart approx size of closed fistAbout 5 inches long and 3 ½ inches wideWeighs just less than 1 poundBeats about 100,000 times each dayPump about 8,000 gallons of blood through

12,000 miles of vessels each dayContracts and relaxes 70-80 bpm

Structure of HeartFour 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 HeartLeft Side Right SideOne ventricleOne atriumMitral valve—connects

left atrium to left ventricle

One ventricleOne atriumTricuspid valve—

connects right atrium to right ventricle

Wall, septum, separates right and left sides

Aortaheart’s main artery carries blood away

from heart to body’s cells

Pulmonary arteryartery that connects

heart to lungsTwo largest veins:

Superior vena cavaInferior vena cava

Structure of Heart

Blood FlowTwo sides of heart

are anatomically and functionally separate pumping unitsRight 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

Heart’s Conduction SystemHeart’s electrical systemConsisting of specialized cells within heart

muscle that carry an electrical signalRegulates pumping of heart

Heart MusclePericardiumEpicardiumMyocardiumEndocardium

BloodOnly tissue that flows throughout bodyCarries oxygen & nutrients to all parts of

body and transports waste products back to lungs, kidneys, and liver for disposal

Essential part of immune systemCrucial for fluid and temperature balanceHydraulic fluid for certain functionsHighway for hormonal messagesComposed of plasma and billions of cells

PlasmaThe yellowish, liquid part of bloodRiver in which blood cells travelMakes up 55% of total volumeCarries blood cells +

Nutrients (sugars, amino acids, fats, salts, minerals)

Waste products (CO2, lactic acid, urea)AntibodiesClotting proteins (called clotting factors)Chemical messengers (hormones)Proteins that help maintain body’s fluid balance

Blood—RBCs & HemoglobinRed Blood Cells (erythrocytes)

Highly specialized cells that have been “stripped” of everything, including nucleus

Major job: transporting oxygenPercentage of RBCs in total blood volume

called hematocritHemoglobin

Special red-colored molecule that fills RBCsPicks up oxygen in areas where O2 is abundant

and releases O2 in tissues where O2 concentration lowest

Blood—White Blood Cells5 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 VesselsHollow tubes running throughout the body5 types

ArteriesArteriolesVeinsVenulesCapillaries

Provide 2 measurements:PulseBlood pressure

ArteriesBlood 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=aortaRuns from chest into

abdomen Receives blood directly

from left ventricle

VeinsBlood vessels that carry

blood back to heartThinner wallContain 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 cavaBring blood from

upper and lower body into right atrium

Venules: smallest veins

CapillariesTiny, 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 ArteriesThe heart’s own system of blood vesselsLocated around heart muscle to provide

blood and oxygen to all parts of heartTwo primary coronary arteries

branch off into smaller vesselsRight coronary artery: feeds right

atrium & ventricle and bottom of left ventricle

Left main coronary artery: supplies blood to rest of heartLeft anterior descendingCircumflex

Blood PressureHeart 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 ctx Average 120 mm/Hg

Diastolic: lowest pressure in heart Relates to ventricular ctx Average 80 mm/Hg

Pulse pressure: difference between diastolic and systolic pressures

PulseRhythmical beating of heartCreated by alternating expansion and

contraction of artery as blood flows through7 areas where pulse can be felt

Brachial arteryCommon carotid arteryFemoral arteryDorsalis pedis arteryPopliteal arteryRadial arteryTemporal artery

Target Heart RatePercentage of the maximum heart rate that is safe

to reach during exerciseAHA recommends 50-75% for average healthy

personCalculated 220-ageTHR is sliding scale that decreases with ageTool for measuring cardiovascular exerciseMaintain THR for 15-30 min daily health benefits

Flow of Blood through HeartSuperior/inferior vena cavaRight atriumTricuspid valveRight ventricleSemi-lunar valvePulmonary artery Lungs

http://www.nhlbi.nih.gov/health/dci/Diseases/hhw/hhw_pumping.html

Flow of Blood through HeartBack to heart via

pulmonary veinLeft atriumBicuspid valveLeft ventricleSemi-lunar valveAortaOrgans in the body

Can you label the heart?