1. Chapter 23
Circulation

2. How Does Gravity Affect Blood Circulation?
How Does Gravity Affect Blood Circulation?
Few animals seem less alike than the giraffe and the corn snake
Despite their differences
They have many features in common

3. Most animals have a circulatory system
That transports O2 and nutrients to cells and takes away CO2 and other wastes
The circulatory system of land animals
Must deal with the problem of gravity

4. Functions of the circulatory system:
transporting oxygen  
transporting carbon dioxide  
transporting nutrients  
transporting metabolic wastes  

5. 23.1 The circulatory system connects with all body tissues
In many animals, microscopic blood vessels called capillaries
Form an intricate network among the tissue
Red
blood
cell
Nuclei of
smooth
muscle
cells
Capillary
LM 700
Figure 23.1A

6. Are the sites of exchange between blood and interstitial fluid
Capillaries
Are the sites of exchange between blood and interstitial fluid
Capillary
Interstitial
fluid
Diffusion of
molecules
Tissue
cell
Figure 23.1B

7. MECHANISMS OF INTERNAL TRANSPORT
23.2 Several types of internal transport have evolved in animals
In cnidarians and flatworms the gastrovascular cavity functions in both digestion and internal transport
In hydra, they do not need a circulatory system because they have very thin body walls & exchange oxygen directly with their environment.  
Mouth
Figure 23.2A
Circular
canal

8. In the open circulatory systems of arthropods and many molluscs, a heart pumps blood through open-ended vessels to bathe tissue cells directly
With an open circulatory system, like in grasshoppers, there is no distinction between blood and interstitial fluid.  
Tubular heart
Pores
Figure 23.2B

9. In closed circulatory systems
A heart pumps blood through arteries to capillaries
Veins return blood to the heart
Capillary beds
Artery
(O2-rich blood)
Arteriole
Venule
Vein
Atrium
Gill
capillaries
Artery
(O2-poor blood)
Heart
Ventricle
Figure 23.2C

10. 23.3 Vertebrate cardiovascular systems reflect evolution
The two-chambered heart of a fish pumps blood in a single circuit
From gill capillaries to systemic capillaries and back to the heart
Gill capillaries
Heart:
Ventricle (V)
Atrium (A)
Figure 23.3A
Systemic capillaries

11. Amphibians and reptiles Have three-chambered hearts Frog Heart
Lung and skin capillaries
Pulmocutaneous
circuit A A V
Right
Left
Systemic
circuit
Figure 23.3B
Systemic capillaries

12. Birds and mammals Have four-chambered hearts
Lung capillaries
Pulmonary
circuit A A V V
Right
Left
Systemic
circuit
Figure 23.3C
Systemic capillaries

13. THE MAMMALIAN CARDIOVACULAR SYSTEM
23.4 The human heart and cardiovascular system are typical of mammals
The mammalian heart
Has two thin-walled atria that pump blood into the ventricles
Has thick-walled ventricles that pump blood to all other body organs
The largest blood vessel in the human body is the aorta
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
(AV) valve
Atrioventricular
(AV) valve
Right
ventricle
Left
ventricle
Figure 23.4A

14. Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
(AV) valve
Atrioventricular
(AV) valve
Right
ventricle
Left
ventricle

17. Blood flow through the human cardiovascular system
Superior
vena cava
Capillaries of
head, chest, and
arms 8
Pulmonary
artery
Pulmonary
artery
Aorta
Capillaries
of right lung 9
Capillaries
of left lung 2 7 2 3 3 4 5 10
Pulmonary
vein 4
Pulmonary
vein 6 1
Right atrium 9
Left atrium
Right ventricle
Left ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal region
and legs 8
Figure 23.4B

18. 23.5 The structure of blood vessels fits their functions
A single layer of epithelial cells
Forms the walls capillaries
Arteries and veins
Have smooth muscle and connective tissue
Capillary
Basement
membrane
Epithelium
Valve
Epithelium
Epithelium
Smooth
muscle
Smooth
muscle
Connective
tissue
Connective
tissue
Artery
Vein
Figure 23.5
Arteriole
Venule

19. 23.6 The heart contracts and relaxes rhythmically
During diastole
Blood flows from the veins into the heart chambers & the heart fills with blood.
During systole
Contractions of the atria push blood into the ventricles
Stronger contractions of the ventricles propel blood into the large arteries; blood leaves the heart.

20. A cardiac cycle Heart is 2 Atria 1 relaxed. contract. AV valves
are open. 2
Atria
contract.
0.1sec
Systole
0.3 sec 3
Ventricles
contract.
Semilunar
valves
are open.
0.4 sec
Diastole
Figure 23.6

21. Cardiac output
the volume of blood pumped by the left ventricle each minute
Heart valves
Prevent the backflow of blood
The sounds of the contractions that you hear are due to the sounds of the valves in the heart closing.  

22. 23.7 The pacemaker sets the tempo of the heartbeat
The pacemaker (SA node) generates electrical signals, that trigger contraction of the atria
The AV node-Relays these signals to the ventricles
Heart Beat
Specialized
muscle fibers
Pacemaker
(SA node)
AV node
Right
atrium
Right
ventricle
Apex 1 2 3 4
ECG
Figure 23.7

23. Is influenced by: An electrocardiogram (ECG)
Records the electrical changes in the heart
Heart rate
Adjusts to body needs
Is influenced by:
emotional cues.
hormones.
exercise.
a pacemaker in the right atrium.

24. CONNECTION 23.8 What is a heart attack?
A heart attack results from the death of cardiac muscle cells
Usually resulting from a blocked coronary artery
Superior
Vena cava
Aorta
Left
coronary
artery
Pulmonary
artery
Right
coronary
artery
Blockage
Dead
muscle
tissue
Figure 23.8A

25. In atherosclerosis Plaques develop in the inner
walls of arteries and can block blood flow
Connective
tissue
Smooth
muscle
Plaque
Epithelium
LM 160 
LM 60 
Figure 23.8B

26. Cardiovascular disease is the leading cause of death in the United States

27. 23.9 Blood exerts pressure on vessel walls
Blood pressure
Is the force blood exerts on vessel walls
Depends on cardiac output and the resistance of vessels

28. Pressure is highest in the arteries And lowest in the veins
120
Systolic
pressure
100
Pressure (mm Hg) 80 60 40
Diastolic
pressure 20
Relative sizes and
numbers
of blood
vessels 50 40
Velocity (cm/sec) 30 20 10
Aorta
Arteries
Vains
Arterioles
Venules
Capillaries
Venae cavae
Figure 23.9A

29. Muscle contractions and one-way valves
Keep blood moving through the veins to the heart
Direction of
blood flow
in vein
Valve
(open)
Skeletal
muscle
Valve
(closed)
Figure 23.9B

30. 23.10 Measuring blood pressure can reveal cardiovascular problems
CONNECTION
23.10 Measuring blood pressure can reveal cardiovascular problems
Blood pressure
Is measured as systolic and diastolic pressures
Blood pressure 110 systolic 70 diastolic (to be measured)
Pressure in cuff above 110
Pressure in cuff at 110
Pressure in cuff at 70
Rubber cuff inflated with air
110
110 70
Sounds audible in stethoscope
Sounds stop
Artery
Artery closed
Figure 23.10 1 2 3 4

31. Hypertension (high blood pressure)
Is a serious cardiovascular problem
Can be caused by smoking

32. 23.11 Smooth muscle controls the distribution of blood
Constriction of arterioles and precapillary sphincters
Controls blood flow through capillary beds
Precapillary sphincters
Thoroughfare
channel
Capillaries
Arteriole
Venule 1
Sphincters relaxed
Thoroughfare
channel
Arteriole
Venule
Figure 23.11 2
Sphincters contracted

33. 23.12 Capillaries allow the transfer of substances through their walls
Interstitial
fluid
Iumen
Capillary
wall
Nucleus of
epithelial
cell
Cleft between
two epithelial
cells of the
capillary wall
Muscle
cell
TEM 5,000
Figure 23.12A

34. By pressure flow through clefts between epithelial cells
The transfer of materials between the blood and interstitial fluid occurs
By diffusion
By pressure flow through clefts between epithelial cells
Tissue cells
Osmotic
pressure
Arterial
end of
capillary
Osmotic
pressure
Venous
end of
capillary
Blood
pressure
Blood
pressure
Interstitial
fluid
Net fluid
Movement out
Net fluid
Movement in
Figure 23.12B

35. Blood pressure forces fluid out of the capillary at the arterial end
And osmotic pressure draws fluid at the venous end

36. STRUCTURE AND FUNCTION OF BLOOD
23.13 Blood consists of red and white blood cells suspended in plasma
Plasma (liquid portion of blood) is about 90% water
And contains various inorganic ions, proteins, nutrients, wastes, gases, and hormones
Plasma (55%)
Constituent
Major functions
Water
Solvent for
carrying other
substances
Salts (ions)
Osmotic balance,
pH buffering, and
nerve and muscle
function
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Centrifuged
blood
sample
Plasma proteins
Osmotic balance
and pH buffering
Fibrinogen
Immunoglobulins
(antibodies)
Clotting
Immunity
Substances transported by blood
Nutrients (e.g., glucose, fatty acids,vitamins) Waste products of metabolism
Respiratory gases (O2 and CO2)
Hormones
Figure (left part)

37. Blood proteins: fighting infection. maintaining osmotic balance.
acting as buffers.   
blood clotting.  

38. Phagocytes are monocytes and neutrophils
Red blood cells (erythrocytes)-Transport O2 bound to hemoglobin (formed in the bone marrow)
White blood cells (leukocytes)-Function both inside and outside the circulatory system to fight infections and cancer
Phagocytes are monocytes and neutrophils  
Cellular elements (45%)
Cell type
Number
per L (mm3) of blood
Functions
Erythrocytes
(red blood cells)
5–6 million
Transport
of oxygen
(and carbon
dioxide)
Centrifuged
blood
sample
Leukocytes
(white blood cells)
5,000–10,000
Defense and
immunity
Basophil
Lymphocyte
Eosinophil
Neutrophil
Monocyte
Figure (right part)
Platelets
250,000–
400,000
Blood clotting

39. CONNECTION 23.14 Too few or too many red blood cells can be unhealthy
Anemia is an abnormally low amount of hemoglobin or red blood cells; usually caused by an iron deficiency.
Colorized SEM 3,400
Figure 23.14

40. The hormone erythropoietin regulates red blood cell production
Human red blood cells circulate in the blood 3 to 4 months before they wear out
Some athletes artificially increase their red blood cell production, a dangerous practice
Blood doping can increase red blood cell concentration

41. 23.15 Blood clots plug leaks when blood vessels are injured
When a blood vessel is damaged, platelets help trigger the conversion of fibrinogen to fibrin, forming a clot that plugs the leak
Blood clots are formed by platelets and the plasma protein, fibrinogen.
Colorized SEM 3,400
Figure 23.15B

42. The blood-clotting process1
Platelets adhere to exposed
connective tissue 2
Platelet plug forms 3
Fibrin clot traps
blood cells
Epithelium
Connective
tissue
Platelet
Platelet plug
Figure 23.15A

43. CONNECTION
23.16 Stem cells offer a potential cure for blood cell diseases
Stem cells divide in bone marrow
To produce all blood cells
And may be used to treat some blood disorders
Cancer of white blood cells is called leukemia
Stem cells
Stem cells
Erythrocytes
Basophils
Platelets
Eosinophils
Figure 23.15B
Monocytes
Neutrophils
Lymphocytes