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