1. Circulation & Gas Exchange
Chapter 42:
Circulation & Gas Exchange

2. Gastrovascular Cavity Open vs. Closed Circulatory System
digestion & distribution of nutrients
2 cell layered thick organisms – Cnidarians
In the mouth, out the mouth

3. Figure 42.2 Internal transport in the cnidarian Aurelia
Circular canal
Radial canal
5 cm
Mouth

4. a) Open circulatory system: fig.42.3
Heart pumps hemolymph into large cavity
VERY inefficient due to mixing of good
& bad substances

5. Figure 42.3 Open and closed circulatory systems
Heart
Hemolymph in sinuses surrounding ograns
Interstitial fluid
Small branch vessels in each organ
Anterior vessel
Lateral vessels
Ostia
Tubular heart
Dorsal vessel (main heart)
Ventral vessels
Auxiliary hearts
(a) An open circulatory system
(b) A closed circulatory system
Heart pump hemolymph into large cavity
VERY inefficient due to mixing of good & bad substances
Heart pump blood through vessels in a complete circuit
More efficient & consistent

6. (b) closed circulatory system
Heart pump blood through vessels in a complete circuit
More efficient & consistent

7. Figure 42.3 Open and closed circulatory systems
Heart
Hemolymph in sinuses surrounding ograns
Interstitial fluid
Small branch vessels in each organ
Anterior vessel
Lateral vessels
Ostia
Tubular heart
Dorsal vessel (main heart)
Ventral vessels
Auxiliary hearts
(a) An open circulatory system
(b) A closed circulatory system
Heart pump hemolymph into large cavity
VERY inefficient due to mixing of good & bad substances
Heart pump blood through vessels in a complete circuit
More efficient & consistent

8. Compare vertebrate hearts
Figure 42.4
Fish:
1atrium & 1 ventricle
single circuit
blood flows from gills directly to rest
of the body
BP is LOW after gill capillaries
Swimming helps blood complete the circuit

9. Figure 42.4 Vertebrate Circulatory Systems
FISHES
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Systemic capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right
Left
Systemic circuit
Pulmocutaneous circuit
Pulmonary circuit
Systemic circulation
Vein
Atrium (A)
Heart: ventricle (V)
Artery
Gill circulation A V
Systemic aorta
Right systemic aorta
FISH
1atrium & 1 ventricle
single circuit
blood flows from gills directly to rest of the body
BP is LOW after gill capillaries
Swimming helps blood complete the circuit

10. Amphibians: 2 atria & 1 ventricle Double circulation blood flow:
heart ventricle  pulmocutaneous circuit heart systemic capillaries
Mixing of blood in ventricle – INEFFICIENT!

11. Figure 42.4 Vertebrate Circulatory Systems
FISHES
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Systemic capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right
Left
Systemic circuit
Pulmocutaneous circuit
Pulmonary circuit
Systemic circulation
Vein
Atrium (A)
Heart: ventricle (V)
Artery
Gill circulation A V
Systemic aorta
Right systemic aorta
AMPHIBIANS
2 atria & 1 ventricle
Double circulation
blood flows from ventricle to pulmocutaneous circuit, back to the heart
& then from the same ventricle to the systemic capillaries
- Mixing of blood in ventricle is INEFFICIENT

12. The heart of a normally developing human fetus has a hole between the left and right atria. In some cases, this hole doesn't not close completely before birth. If the hole weren't surgically corrected, how would it affect the O2 content of the blood entering the systemic circuit?

13. Reptiles: 2 atria & 1 ventricle pulmonary circuit since skin is dry
90% ridge between right & left ventricles
ridge is complete in crocodilians
Mixing of blood in ventricle is less

14. Figure 42.4 Vertebrate Circulatory Systems
FISHES
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Systemic capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right
Left
Systemic circuit
Pulmocutaneous circuit
Pulmonary circuit
Systemic circulation
Vein
Atrium (A)
Heart: ventricle (V)
Artery
Gill circulation A V
Systemic aorta
Right systemic aorta
REPTILES
2 atria & 1 ventricle
pulmonary circuit since skin is dry
90% ridge between right & left ventricles
ridge is complete in crocodilians
- Mixing of blood in ventricle is less

15. Mammals: 2 atria & 2 ventricles no mixing of O2-rich & O2 poor blood
2 complete circuits – pulmonary & systemic

16. Figure 42.4 Vertebrate Circulatory Systems
FISHES
AMPHIBIANS
REPTILES (EXCEPT BIRDS)
MAMMALS AND BIRDS
Systemic capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right
Left
Systemic circuit
Pulmocutaneous circuit
Pulmonary circuit
Systemic circulation
Vein
Atrium (A)
Heart: ventricle (V)
Artery
Gill circulation A V
Systemic aorta
Right systemic aorta
MAMMALS
2 atria & 2 ventricles
no mixing of O2-rich & O2 poor blood
2 complete circuits – pulmonary & systemic

17. Figure 42.5 The mammalian cardiovascular system: an overview
Route of blood flow thru our circulatory system:
Right atrium
Right ventricle
Posterior
vena cava
Capillaries of
abdominal organs
and hind limbs
Aorta
Left ventricle
Left atrium
Pulmonary
vein
artery
Capillaries
of left lung
head and
forelimbs
Anterior
of right lung 1 10 11 5 4 6 2 9 3 7 8

18. route of blood flow through our CV system: Right ventricle
Chapter 42: Circulation and Gas Exchange
route of blood flow through our CV system:
Right ventricle
Pulmonary artery
Pulmonary capillaries
Pulmonary veins
Left atrium
Left ventricle
Aorta arteries
Capillaries above heart – head & arms
Capillaries below heart – abdominal organs & legs
Anterior vena cava – from above heart
Posterior vena cava – from below heart
Right atrium

19. Figure 42.6 The mammalian heart: a closer look
Aorta
Pulmonary artery
Left atrium
Pulmonary veins
Semilunar valve
Atrioventricular valve
Left ventricle
Right ventricle
Anterior vena cava
Posterior vena cava
Right atrium

20. How does structure fit function of the heart?
Atria have thin walls
pump to ventricles
Ventricles have THICK walls
left is thickest
Valves prevent back flow
Atrioventricular valves (A-V)
between atria & ventricles
Semilunar valves (S-L)- b/t ventricles & exit vessels

21. Figure 42.8 The control of heart rhythm
heart beat control:
SA node (pacemaker)
AV node
Bundle branches
Heart apex
Purkinje fibers 1 2
Signals are delayed
at AV node.
Pacemaker generates wave of signals to contract. 3
Signals pass
to heart apex. 4
Signals spread
throughout ventricles.
ECG

22. Figure 42.9 The structure of blood vessels
blood flow thru our vessels:
Artery
Vein
100 µm
Arteriole
Venule
Connective tissue
Smooth muscle
Endothelium
Valve
Basement membrane
Capillary

23. Figure 42.10 Blood flow in veins
Direction of blood flow in vein (toward heart)
Valve (open)
Skeletal muscle
Valve (closed)

24. vessel size vs. BP vs. velocity?
Figure 42.11 The interrelationship of blood flow velocity, cross-sectional area of blood vessels, and blood pressure
vessel size vs. BP vs. velocity?
5,000 4,000
3,000
2,000
1,000
50 40 30 20 10 60 40
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Venae cavae
Pressure (mm Hg)
Velocity (cm/sec)
Area (cm2)
Systolic pressure
Diastolic pressure
Capillaries increase surface area
Cells flow through single file
Slow flow means better ability for exchange

25. Arterial end of capillary
Figure 42.14 Fluid exchange between capillaries and the interstitial fluid
Tissue cell
INTERSTITIAL FLUID
Net fluid
movement out
Net fluid
movement in
Capillary
Capillary
Red
blood
cell
15 m
At the venule end
of a capillary, blood
pressure is less than osmotic pressure, and
fluid flows from the
interstitial fluid into
the capillary.
At the arterial end of a
capillary, blood pressure is
greater than osmotic pressure,
and fluid flows out of the
capillary into the interstitial fluid.
Direction of
blood flow
Blood pressure
Osmotic pressure
Inward flow
Pressure
Outward flow
Arterial end of capillary
Venule end

26. Figure 42.15 The composition of mammalian blood
blood components:
Plasma 55%
Constituent
Major functions
Water
Solvent for
carrying other
substances
Sodium
Potassium
Calcium Magnesium
Chloride
Bicarbonate
Osmotic balance
pH buffering, and
regulation of
membrane
permeability
Albumin
Fibringen
Immunoglobulins
(antibodies)
Plasma proteins
Icons (blood electrolytes
Osmotic balance,
pH buffering
Clotting
Defense
Substances transported by blood
Nutrients (such as glucose, fatty acids, vitamins)
Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Cellular elements 45%
Cell type
Number per L (mm3) of blood
Separated blood elements
Functions
Erythrocytes (red blood cells)
5–6 million
Transport oxygen and help transport carbon dioxide
Leukocytes (white blood cells)
5,000–10,000
Defense and immunity
Eosinophil
Basophil
Platelets
Neutrophil
Monocyte
Lymphocyte
250,000 400,000
Blood clotting

27. Figure 42.16 Differentiation of blood cells
B cells
T cells
Lymphoid stem cells
Pluripotent stem cells (in bone marrow)
Myeloid stem cells
Erythrocytes
Platelets
Monocytes
Neutrophils
Eosinophils
Basophils
Lymphocytes
Origin of blood cells:
Erythropoeitin (EPO)
– kidney hormone
released in response
to low O2 to stimulate
production of erythrocytes

28. Blood clot: Figure 42.17 Blood clotting Collagen fibers Platelet plug3
This seal is reinforced by a clot of fibrin when vessel damage is severe. Fibrin is formed via a multistep process: Clotting factors released from the clumped platelets or damaged cells mix with clotting factors in the plasma, forming an activation cascade that converts a plasma protein called prothrombin to its active form, thrombin. Thrombin itself is an enzyme that catalyzes the final step of the clotting process, the conversion of fibrinogen to fibrin. The threads of fibrin become interwoven into a patch (see colorized SEM). 1
The clotting process begins when the endothelium of a vessel is damaged, exposing connective tissue in the vessel wall to blood. Platelets
adhere to collagen fibers in
the connective tissue and release a substance that
makes nearby platelets sticky. 2
The platelets form a plug that provides
emergency protection
against blood loss.
Collagen fibers
Platelet plug
Fibrin clot
Red blood cell
Platelet releases chemicals that make nearby platelets sticky
Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K)
Prothrombin
Thrombin
Fibrinogen
Fibrin
5 µm

29. CV diseases: >50% of deaths due to CV disease
LDLs – low-density lipoproteins - bad cholesterol
Associated with arterial plaques
HDLs – high-density lipoproteins – good cholesterol
Reduce deposition of cholesterol

30. Figure 42.18 Atherosclerosis
(a) Normal artery
(b) Partly clogged artery
50 µm
250 µm
Smooth muscle
Connective tissue
Endothelium
Plaque
Atherosclerosis
cholesterol plaques in arteries slows blood flow
Arteriosclerosis
hardening of the arteries due to Ca+2 added to plaques

31. CV diseases: Hypertension – high BP Heart attack –
death of heart muscle
due to blocked coronary arteries
Stroke –
death of nervous tissue in brain
due to blocked brain arteries