Essential Knowledge: 2.A.3 Organisms must exchange matter with the environment to grow, reproduce, and maintain organization2.D.2 Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different environments.4.A.4 Organisms exhibit complex Properties due to interactions between constituent parts4.B.2 Cooperative interactions within organisms promote efficiency in the use of energy and matter

How do simple organisms like jelly fish and flat worms exchange reactants and products of cellular respiration?◦ Simple animals have a body wall that is only two

cells thick and that encloses a gastrovascular cavity

◦ This cavity functions in both digestion and distribution of substances throughout the body

◦ Materials can diffuse in or out of the gastrovascular cavity as needed.

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-2

Circularcanal

Radial canalMouth

(a) The moon jelly Aurelia, a cnidarian The planarian Dugesia, aflatworm

(b)

MouthPharynx

2 mm5 cm

How do more complex organisms exchanges the reactants and products of cellular respiration?◦ They have either an open or closed circulatory system.

How does an open circulatory system work?◦ In insects, other arthropods, and most molluscs,

blood bathes the organs directly in an open circulatory system

◦ In an open circulatory system, there is no distinction between blood and interstitial fluid, and this general body fluid is more correctly called hemolymph

Circulation of Glucose, Oxygen, and Carbon Dioxide

How does a closed circulatory system work?◦ In a closed circulatory system, blood is

confined to vessels and is distinct from the interstitial fluid

◦ Closed systems are more efficient at transporting circulatory fluids to tissues and cells

What do we call our circulatory system?◦ Humans and other vertebrates have a closed

circulatory system, often called the cardiovascular system

◦ The three main types of blood vessels are arteries, veins, and capillaries

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-3

Heart

Hemolymph in sinusessurrounding organs

Heart

Interstitialfluid

Small branch vesselsIn each organ

Blood

Dorsal vessel(main heart)

Auxiliary hearts Ventral vessels

(b) A closed circulatory system(a) An open circulatory system

Tubular heart

Pores

What are the major components of the vertebrate circulatory system?◦ Arteries branch into arterioles and carry blood to

capillaries ◦ Networks of capillaries called capillary beds are

the sites of chemical exchange between the blood and interstitial fluid

◦ Venules converge into veins and return blood from capillaries to the heart

◦ Vertebrate hearts contain two or more chambers◦ Blood enters through an atrium and is pumped

out through a ventricle

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-4

Artery

Ventricle

AtriumHeart

Vein

Systemic capillaries

Systemiccirculation

Gillcirculation

Gill capillaries

Single circulatory loop with a 2 chambered heart

Fig. 42-5

Amphibians

Lung and skin capillaries

Pulmocutaneouscircuit

Atrium (A)

Ventricle (V)

Atrium (A)

Systemiccircuit

Right Left

Systemic capillaries

Reptiles (Except Birds)

Lung capillaries

Pulmonarycircuit

Rightsystemicaorta

Right LeftLeftsystemicaorta

Systemic capillaries

A A

VV

Systemic capillaries

Pulmonarycircuit

Systemiccircuit

Right Left

A A

VV

Lung capillaries

Mammals and Birds

Double heart circulation w/ 3 chambered

Double circulation with a 3 chambered heart – ventricle partially divided

Double circulation with a 4 chambered heart

How does blood flow in a mammal?◦ Blood begins its flow with the right ventricle pumping

blood to the lungs◦ In the lungs, the blood loads O2 and unloads CO2

◦ Oxygen-rich blood from the lungs enters the heart at the left atrium and is pumped through the aorta to the body tissues by the left ventricle

◦ The aorta provides blood to the heart through the coronary arteries

◦ Blood returns to the heart through the superior vena cava (blood from head, neck, and forelimbs) and inferior vena cava (blood from trunk and hind limbs)

◦ The superior vena cava and inferior vena cava flow into the right atrium

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-6

Superiorvena cava

Pulmonaryartery

Capillariesof right lung

3

7

3

8

9

24

11

51

10

Aorta

Pulmonaryvein

Right atrium

Right ventricle

Inferiorvena cava

Capillaries ofabdominal organsand hind limbs

Pulmonaryvein

Left atrium

Left ventricle

Aorta

Capillariesof left lung

Pulmonaryartery

Capillaries ofhead andforelimbs

Fig. 42-7

Pulmonary artery

Rightatrium

Semilunarvalve

Atrioventricularvalve

Rightventricle

Leftventricle

Atrioventricularvalve

Leftatrium

Semilunarvalve

Pulmonaryartery

Aorta

How does the heart contract? What are the two phases of the cardiac cycle?◦ The contraction, or pumping, phase is called

systole◦ The relaxation, or filling, phase is called diastole

What is another name for the heart rate?◦ The heart rate, also called the pulse, is the

number of beats per minute

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-8

Semilunarvalvesclosed

0.4 secAVvalvesopen

Atrial andventriculardiastole

1

2

0.1 sec

Atrial systole;ventriculardiastole

3

0.3 sec

Semilunarvalvesopen

AV valvesclosed

Ventricular systole;atrial diastole

What are the four valves in the heart called? And what is their purpose?◦ Four valves prevent backflow of blood in the heart◦ The atrioventricular (AV) valves separate each

atrium and ventricle◦ The semilunar valves control blood flow to the

aorta and the pulmonary artery◦ The “lub-dup” sound of a heart beat is caused by

the recoil of blood against the AV valves (lub) then against the semilunar (dup) valves

Circulation of Glucose, Oxygen, and Carbon Dioxide

How does the heart maintain its rhythmic beat?◦ The sinoatrial (SA) node, or pacemaker, sets

the rate and timing at which cardiac muscle cells contract

◦ Impulses from the SA node travel to the atrioventricular (AV) node

◦ At the AV node, the impulses are delayed and then travel to the Purkinje fibers that make the ventricles contract

◦ The pacemaker (SA node) is influenced by nerves, hormones, body temperature, and exercise

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-9-5

Signals spreadthroughoutventricles.

4

Purkinjefibers

Pacemakergenerates wave ofsignals to contract.

1

SA node(pacemaker)

ECG

Signals aredelayed atAV node.

2

AVnode

Signals passto heart apex.

3

Bundlebranches Heart

apex

How is the structure of blood vessels adapted to transport material throughout the body?◦ Capillaries have thin walls, the endothelium plus its

basement membrane, to facilitate the exchange of materials

◦ Arteries and veins have an endothelium, smooth muscle, and connective tissue

◦ Arteries have thicker walls than veins to accommodate the high pressure of blood pumped from the heart

◦ In the thinner-walled veins, blood flows back to the heart mainly as a result of muscle action, valves prevent back flow

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-10Artery Vein

SEM100 µm

Endothelium

Artery

SmoothmuscleConnectivetissue Capillary

Basal lamina

Endothelium

Smoothmuscle

Connectivetissue

Valve

Vein

Arteriole Venule

Red blood cell

Capillary

15 µ

mLM

How does blood flow change as it moves from arteries to capillaries to veins?◦ Blood flow is fast in arteries due to pumping of

the heart◦ Blood flow slows in capillaries as the volume from

one artery spreads to feed an entire capillary bed – this is good it slows things down and allows for exchange of materials

◦ Blood flow increases slightly in veins due to decreased surface area

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-11

5,0004,0003,000

2,0001,000

0

0

5040302010

120

80100

6040200

Are

a (

cm

2)

Velo

cit

y(c

m/s

ec)

Pre

ssu

re(m

m H

g)

Aort

a

Art

eri

es

Art

eri

ole

s

Cap

illa

ries

Ven

ule

s

Vein

s

Ven

ae c

avae

Diastolicpressure

Systolicpressure

How can blood flow through capillaries be controlled?◦ Two mechanisms regulate distribution of blood in

capillary beds: Contraction of the smooth muscle layer in the

wall of an arteriole constricts the vessel Precapillary sphincters control flow of blood

between arterioles and venules

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-15

Precapillary sphinctersThoroughfarechannel

Arteriole

Capillaries

Venule

(a) Sphincters relaxed

(b) Sphincters contracted

Arteriole Venule

Where does the critical exchange of nutrients and gasses takes place in the circulatory system?◦ The critical exchange of substances between the

blood and interstitial fluid takes place across the thin endothelial walls of the capillaries

◦ The difference between blood pressure and osmotic pressure drives fluids out of capillaries at the arteriole end and into capillaries at the venule end

Circulation of Glucose, Oxygen, and Carbon Dioxide

Fig. 42-16

Body tissue

CapillaryINTERSTITIAL FLUID

Net fluidmovement out

Direction ofblood flow

Net fluidmovement in

Blood pressure

Inward flow

Outward flowOsmotic pressure

Arterial end of capillary Venous end

Pre

ssu

re