chapter 42 circulation and gas exchange. label the heart vessels & valves trace the flow of...

Chapter 42 Chapter 42 Circulation and Gas Circulation and Gas ExchangeExchange

Label the heart vessels & valvesLabel the heart vessels & valvesTrace the flow of blood beginning with return through the Trace the flow of blood beginning with return through the

Vena cava (list)Vena cava (list)

If you are only a couple of cell If you are only a couple of cell layers thick or very flat—a simple layers thick or very flat—a simple distribution system works just fine.distribution system works just fine.

Gastrovascular cavity Gastrovascular cavity in cnidariansin cnidarians

Highly branched Highly branched gastrovascular cavity gastrovascular cavity in flatwormsin flatworms

Circulatory SystemsCirculatory Systems

Complex animalsComplex animals 2 types2 types 3 basic components:3 basic components:

1. circulatory fluid (blood)1. circulatory fluid (blood)

2. set of tubes (blood vessels)2. set of tubes (blood vessels)

3. muscular pump (heart)3. muscular pump (heart)

The 2 Types of Circulatory Systems: The 2 Types of Circulatory Systems:

Open circulatoryOpen circulatory arthropods, mollusks arthropods, mollusks

circulatory fluid directly bathes cells--exchangecirculatory fluid directly bathes cells--exchange

hemolymphhemolymph (blood & interstitial fluid) •pumped into sinuses (blood & interstitial fluid) •pumped into sinuses (spaces surrounding organs) through vessels(spaces surrounding organs) through vessels

Closed circulatoryClosed circulatory:: blood confined to vessels; blood confined to vessels; earthworm, squid, vertebratesearthworm, squid, vertebrates

Cardiovascular systemCardiovascular system vertebrates •vertebrates • blood-circulatory fluid- circulates within vessels blood-circulatory fluid- circulates within vessels

(arteries, veins, capillaries)(arteries, veins, capillaries) Chemical exchange at capillariesChemical exchange at capillaries

Within organs:Within organs: Arteries arterioles capillary bedsArteries arterioles capillary beds

tissues – exchange venules veinstissues – exchange venules veins

return blood to heartreturn blood to heart

ArteriesArteries: carry blood AWAY from the heart: carry blood AWAY from the heart

Veins:Veins: return blood TO THE HEART return blood TO THE HEART

The Vertebrate HeartThe Vertebrate Heart

Atria:Atria: receive blood receive blood returningreturning to the to the heartheart

Ventricles:Ventricles: pump blood out of the heart pump blood out of the heart

Generalized Circulatory schemesGeneralized Circulatory schemes FishFish: 2-chambered heart (1 atrium & 1 ventricle); single circuit : 2-chambered heart (1 atrium & 1 ventricle); single circuit

of blood flow. Heart-to gills picks up O2, eliminates CO2--to of blood flow. Heart-to gills picks up O2, eliminates CO2--to systemic capillaries—then back to heart.systemic capillaries—then back to heart. Disadvantage: low pressure from GillsDisadvantage: low pressure from Gills

Generalized Circulatory schemesGeneralized Circulatory schemes AmphibiansAmphibians: 3-chambered heart; 1 Ventricle, 2 Atria; 2 circuits of blood : 3-chambered heart; 1 Ventricle, 2 Atria; 2 circuits of blood

flow- (double circulation) flow- (double circulation)

1.pulmocutaneous1.pulmocutaneous (lungs and skin); (lungs and skin);

2.systemic (some mixing of O2-rich and O2-poor blood occurs)2.systemic (some mixing of O2-rich and O2-poor blood occurs) Mammals, birds, crocodiliansMammals, birds, crocodilians: 4-chambered heart; : 4-chambered heart; double circulationdouble circulation; ;

complete separation between oxygen-rich and oxygen poor blood (2 complete separation between oxygen-rich and oxygen poor blood (2 ventricles)ventricles)

The mammalian heartThe mammalian heart located beneath located beneath consists mostly of cardiac muscle.consists mostly of cardiac muscle.

Two atria: relatively thin walls collection chambers for blood returning to the heart.

The ventricles have thicker walls and contract much more strongly than the atria.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Double circulationDouble circulation Advantage--Provides Advantage--Provides vigorous flow of blood-vigorous flow of blood-blood pumped through blood pumped through heart 2 TIMESheart 2 TIMES

From right ventricle to lungs From right ventricle to lungs via pulmonary arteriesvia pulmonary arteries through through semilunar valve (pulmonary semilunar valve (pulmonary circulation)circulation)

Capillary beds in lungs to left Capillary beds in lungs to left atrium via pulmonary veinsatrium via pulmonary veins

Left atrium to left ventricleLeft atrium to left ventricle (through atrioventricular valve) (through atrioventricular valve) to aortato aorta

Aorta to coronary arteriesAorta to coronary arteries; ; then systemic circulationthen systemic circulation

Back to heart via two venae Back to heart via two venae cavae (superior and inferior); cavae (superior and inferior); right atriumright atrium

The mammalianThe mammalian heart heart

Cardiac cycleCardiac cycle:: sequence of filling and sequence of filling and pumpingpumping SystoleSystole- contractioncontraction DiastoleDiastole- relaxationrelaxation

Cardiac outputCardiac output: volume of : volume of blood per minuteblood per minute

Heart rateHeart rate- number of - number of beats per minutebeats per minute

Stroke volumeStroke volume- amount of - amount of blood pumped with each blood pumped with each contractioncontraction

Heart ValvesHeart Valves Prevent backflowPrevent backflow Keep blood moving in correct directionKeep blood moving in correct direction

AV valvesAV valves close at ventricular contraction close at ventricular contraction

Semilunar ValvesSemilunar Valves: at the 2 arterial exits of : at the 2 arterial exits of the heartthe heart

forced open at ventricular contractionforced open at ventricular contraction

(arteries stretch under this pressure)(arteries stretch under this pressure)

For a human at rest with a pulse of about 75 beat per minute, one complete cardiac cycle takes about 0.8 sec.(1) During the relaxation phase (atria and

ventricles in diastole) lasting about 0.4 sec, blood returning from the large veins flows into atria and ventricles.

(2) A brief period (about 0.1 sec) of atrial systole forces all the remaining blood out of the atria and into the ventricles.

(3) During the remaining 0.3 sec of the cycle, ventricular systole pumps blood into the large arteries.


Cardiac outputCardiac output depends on two factors: depends on two factors: 1. the rate of contraction or 1. the rate of contraction or heart rateheart rate (number of (number of

beats per second)beats per second) and and stroke volumestroke volume, the amount of blood pumped by , the amount of blood pumped by

the left ventricle in each contraction.the left ventricle in each contraction. The average stroke volume for a human is about 75 mL.The average stroke volume for a human is about 75 mL. Cardiac output can increase about fivefold during heavy Cardiac output can increase about fivefold during heavy

exercise.exercise. Heart rate can be measured indirectly by measuring Heart rate can be measured indirectly by measuring

your your pulsepulse - - the rhythmic stretching of arteries the rhythmic stretching of arteries caused by the pressure of blood pumped by the caused by the pressure of blood pumped by the ventricles.ventricles.


A defect in one or more of the valves causes a heart murmur, which may be detectable as a hissing sound when a stream of blood squirts backward through a valve. born with damage to the valves by infection (rheumatic

fever) Most heart murmurs do not reduce the

efficiency of blood flow enough to warrant surgery.


Continuity and control of the heartbeat. Each cell has its own intrinsic contraction

rhythm. Synchronized by the sinoatrial (SA) node, or

pacemaker which sets the rate and timing at which all cardiac

muscle cells contract.

Located in the wall of the right atrium.


The cardiac cycle is regulated by electrical impulses that radiate throughout the heart. Cardiac muscle cells are electrically coupled

by intercalated disks between adjacent cells.


Fig. 42.7

(1) The SA node generates electrical impulses that spread rapidly (2) through the wall of the atria, making them contract in unison.

Delayed by about 0.1 sec at the atrioventricular (AV) node, the relay point to the ventricle, allowing the atria to empty completely before the ventricles contract.

(3) Specialized muscle fibers called bundle branches and Purkinje fibers conduct the signals to the apex of the heart and (4) throughout the ventricular walls.

This stimulates the ventricles to contract from the apex toward the atria, driving blood into the large arteries.


Impulses generated during the heart cycle produce electrical currents that are conducted through body fluids to the skin.

Here, the currents can be detected by electrodes and recorded as an electrocardiogram (ECG or EKG).


While the SA node sets the tempo for the entire heart, it is influenced by a variety of physiological cues. Two sets of nerves affect heart rate with one set

speeding up the pacemaker and the other set slowing it down Heart rate is a compromise regulated by the opposing

actions of these two sets of nerves.

hormones. For example, epinephrine from the adrenal glands

increases heart rate.

temperature and with exercise. .


arteries and veins have three similar layers. On the outside, a layer of connective tissue with

elastic fibers allows the vessel to stretch and recoil.

A middle layer has smooth muscle and more elastic fibers.

Lining the lumen of all blood vessels, including capillaries, is an endothelium, a single layer of flattened cells that minimizes resistance to blood flow.

5. Structure of arteries, veins, 5. Structure of arteries, veins, and capillaries and capillaries


Structural &functionStructural &function Capillaries lack the two outer layers and their Capillaries lack the two outer layers and their

very thin very thin


Fig. 42.8

Arteries have thicker middle and outer layers than veins. strength to accommodate blood pumped

rapidly and at high pressure by the heart. Their elasticity (elastic recoil) helps maintain

blood pressure even when the heart relaxes..


The thinner-walled veins convey blood back to the heart at low velocity and pressure. Blood flows mostly as a result of skeletal

muscle contractions when we move that squeeze blood in veins.

Within larger veins, flaps of tissues act as one-way valves that allow blood to flow only toward the heart.


Fig. 42.9

BloodBlood Plasma: liquid matrix of blood in which cells are suspended (90% Plasma: liquid matrix of blood in which cells are suspended (90%

water)water) Erythrocytes (RBCs): transport OErythrocytes (RBCs): transport O22 via hemoglobin via hemoglobin Leukocytes (WBCs): defense and immunityLeukocytes (WBCs): defense and immunity Platelets: clottingPlatelets: clotting Stem cells: pluripotent cells in the red marrow of bonesStem cells: pluripotent cells in the red marrow of bones Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia;

thrombus (clot)thrombus (clot)

Cardiovascular diseaseCardiovascular disease

Cardiovascular disease Cardiovascular disease (>50% (>50% of all deaths)of all deaths)

Heart attackHeart attack- death of cardiac - death of cardiac tissue due to coronary blockagetissue due to coronary blockage

StrokeStroke- death of nervous tissue - death of nervous tissue in brain due to arterial blockage in brain due to arterial blockage

AtherosclerosisAtherosclerosis: arterial plaques : arterial plaques depositsdeposits

ArteriosclerosisArteriosclerosis: plaque : plaque hardening by calcium depositshardening by calcium deposits

HypertensionHypertension: high blood : high blood pressurepressure

HypercholesterolemiaHypercholesterolemia::LDL, HDLLDL, HDL

Gas exchangeGas exchange

COCO22 <---> O <---> O22

Aquatic:Aquatic: •gills •ventilation•gills •ventilation ••countercurrent countercurrent exchangeexchange

Terrestrial: Terrestrial: •tracheal systems •lungs•tracheal systems •lungs

Mammalian respiratory systemsMammalian respiratory systems Larynx (upper part of Larynx (upper part of

respiratory tract)respiratory tract) Vocal cords (sound Vocal cords (sound

production)production) Trachea (windpipe)Trachea (windpipe)

Bronchi (tube to lungs)Bronchi (tube to lungs) Bronchioles Bronchioles Alveoli (air sacs)Alveoli (air sacs) Diaphragm (breathing muscle)Diaphragm (breathing muscle)

BreathingBreathing Positive pressure breathingPositive pressure breathing: pushes air into lungs (frog): pushes air into lungs (frog) Negative pressure breathingNegative pressure breathing:: pullspulls air into lungs (mammals)air into lungs (mammals) InhalationInhalation:: diaphragm contractiondiaphragm contraction;; Exhalation Exhalation: diaphragm : diaphragm

relaxationrelaxation Tidal volumeTidal volume: amount of air : amount of air inhaled and exhaledinhaled and exhaled with each breath with each breath

(500ml)(500ml) Vital capacityVital capacity: : maximum tidal volume during forced breathingmaximum tidal volume during forced breathing (4L) (4L) RegulationRegulation: CO: CO22 concentration in blood ( concentration in blood (medulla oblongatamedulla oblongata).). Detects blood pH changesDetects blood pH changes

Respiratory pigments: gas Respiratory pigments: gas transporttransport

Respiratory PigmentsRespiratory Pigments Oxygen transportOxygen transport-- HemocyaninHemocyanin: found in hemolymph of : found in hemolymph of

arthropods and mollusks (Cu)arthropods and mollusks (Cu) HemoglobinHemoglobin: vertebrates (Fe) : vertebrates (Fe) Carbon dioxide transportCarbon dioxide transport-- Blood plasma (7%)Blood plasma (7%) Hemoglobin (23%)Hemoglobin (23%) Bicarbonate ions (70%)Bicarbonate ions (70%) Deep-diving air-breathersDeep-diving air-breathers-- MyoglobinMyoglobin: oxygen storing protein: oxygen storing protein

Cooperative oxygen bindingCooperative oxygen binding Diffusion of O2 in air greaterDiffusion of O2 in air greater

Drop in pH lowers the affinity of hemoglobin Drop in pH lowers the affinity of hemoglobin for O2for O2

Bohr ShiftBohr Shift

The heartbeatThe heartbeat

Label the pictures below.Label the pictures below. Describe or list the steps in the Control of Heart RhythmDescribe or list the steps in the Control of Heart Rhythm

chapter 42 circulation and gas exchange. label the heart vessels & valves trace the flow of...

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