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1/05/12 Overview: Trading Places Circulatory System
or Blood!!
BIOL212 •  Every organism must exchange materials with its environment •  Exchanges ul?mately occur at the cellular level by crossing the plasma membrane •  In unicellular organisms, these exchanges occur directly with the environment © 2011 Pearson Education, Inc.
Figure 42.1
•  For most cells making up mul?cellular organisms, direct exchange with the environment is not possible •  Gills are an example of a specialized exchange system in animals –  O2 diffuses from the water into blood vessels –  CO2 diffuses from blood into the water •  Internal transport and gas exchange are func?onally related in most animals © 2011 Pearson Education, Inc.
Concept 42.1: Circulatory systems link exchange surfaces with cells throughout the body •  Diffusion ?me is propor?onal to the square of the distance •  Diffusion is only efficient over small distances •  In small and/or thin animals, cells can exchange materials directly with the surrounding medium •  In most animals, cells exchange materials with the environment via a fluid-­‐filled circulatory system © 2011 Pearson Education, Inc.
Gastrovascular Cavi?es •  Some animals lack a circulatory system •  Some cnidarians, such as jellies, have elaborate gastrovascular cavi?es •  A gastrovascular cavity func?ons in both diges?on and distribu?on of substances throughout the body •  The body wall that encloses the gastrovascular cavity is only two cells thick •  Flatworms have a gastrovascular cavity and a large surface area to volume ra?o © 2011 Pearson Education, Inc.
1 1/05/12 Figure 42.2
Circular
canal
Figure 42.2a
Circular
canal
Mouth
Mouth
Gastrovascular
cavity
Mouth
Pharynx
Radial canals
2 mm
5 cm
(a) The moon jelly Aurelia, a cnidarian
(b) The planarian Dugesia, a flatworm
Radial canals
5 cm
(a) The moon jelly Aurelia, a cnidarian
Figure 42.2b
Evolu?onary Varia?on in Circulatory Systems Gastrovascular
cavity
•  A circulatory system minimizes the diffusion distance in animals with many cell layers Mouth
Pharynx
2 mm
(b) The planarian Dugesia, a flatworm
© 2011 Pearson Education, Inc.
General Proper+es of Circulatory Systems •  A circulatory system has –  A circulatory fluid –  A set of interconnec?ng vessels –  A muscular pump, the heart •  The circulatory system connects the fluid that surrounds cells with the organs that exchange gases, absorb nutrients, and dispose of wastes •  Circulatory systems can be open or closed, and vary in the number of circuits in the body © 2011 Pearson Education, Inc.
Open and Closed Circulatory Systems •  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 dis?nc?on between blood and inters??al fluid, and this general body fluid is called hemolymph © 2011 Pearson Education, Inc.
2 1/05/12 Figure 42.3
Figure 42.3a
(a) An open circulatory system
(a) An open circulatory system
Heart
(b) A closed circulatory system
Heart
Heart
Interstitial fluid
Hemolymph in sinuses
surrounding organs
Pores
Hemolymph in sinuses
surrounding organs
Blood
Small branch
vessels in
each organ
Dorsal
Auxiliary
vessel
hearts
(main heart)
Tubular heart
Pores
Ventral vessels
Tubular heart
Figure 42.3b
(b) A closed circulatory system
•  In a closed circulatory system, blood is confined to vessels and is dis?nct from the inters??al fluid •  Closed systems are more efficient at transpor?ng circulatory fluids to ?ssues and cells •  Annelids, cephalopods, and vertebrates have closed circulatory systems Heart
Interstitial fluid
Blood
Small branch
vessels in
each organ
Dorsal
Auxiliary
vessel
hearts
(main heart)
Ventral vessels
© 2011 Pearson Education, Inc.
Organiza?on of Vertebrate Circulatory Systems •  Humans and other vertebrates have a closed circulatory system called the cardiovascular system •  The three main types of blood vessels are arteries, veins, and capillaries •  Blood flow is one way in these vessels © 2011 Pearson Education, Inc.
•  Arteries branch into arterioles and carry blood away from the heart to capillaries •  Networks of capillaries called capillary beds are the sites of chemical exchange between the blood and inters??al fluid •  Venules converge into veins and return blood from capillaries to the heart © 2011 Pearson Education, Inc.
3 1/05/12 Single Circula+on •  Arteries and veins are dis?nguished by the direc?on of blood flow, not by O2 content •  Vertebrate hearts contain two or more chambers •  Blood enters through an atrium and is pumped out through a ventricle © 2011 Pearson Education, Inc.
•  Bony fishes, rays, and sharks have single circula?on with a two-­‐chambered heart •  In single circula7on, blood leaving the heart passes through two capillary beds before returning © 2011 Pearson Education, Inc.
Figure 42.4
Figure 42.4a
(a) Single circulation
(a) Single circulation
(b) Double circulation
Pulmonary circuit
Gill
capillaries
Gill
capillaries
Lung
capillaries
Artery
Artery
Heart:
A
Atrium (A)
V
Right
Ventricle (V)
Heart:
A
Atrium (A)
V
Left
Ventricle (V)
Vein
Vein
Systemic
capillaries
Body
capillaries
Body
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
Key
Oxygen-rich blood
Oxygen-poor blood
Figure 42.4b
(b) Double circulation
Double Circula+on Pulmonary circuit
Lung
capillaries
•  Amphibian, rep?les, and mammals have double circula7on •  Oxygen-­‐poor and oxygen-­‐rich blood are pumped separately from the right and le[ sides of the heart A
V
Right
A
V
Left
Systemic
capillaries
Key
Systemic circuit
Oxygen-rich blood
Oxygen-poor blood
© 2011 Pearson Education, Inc.
4 1/05/12 •  In rep?les and mammals, oxygen-­‐poor blood flows through the pulmonary circuit to pick up oxygen through the lungs •  In amphibians, oxygen-­‐poor blood flows through a pulmocutaneous circuit to pick up oxygen through the lungs and skin •  Oxygen-­‐rich blood delivers oxygen through the systemic circuit •  Double circula?on maintains higher blood pressure in the organs than does single circula?on © 2011 Pearson Education, Inc.
Adaptations of Double Circulatory Systems
•  Hearts vary in different vertebrate groups © 2011 Pearson Education, Inc.
Figure 42.5a
Amphibians
Pulmocutaneous circuit
Amphibians
Lung
and skin
capillaries
•  Frogs and other amphibians have a three-­‐chambered heart: two atria and one ventricle •  The ventricle pumps blood into a forked artery that splits the ventricle s output into the pulmocutaneous circuit and the systemic circuit •  When underwater, blood flow to the lungs is nearly shut off Atrium
(A)
Atrium
(A)
Right
Left
Ventricle (V)
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2011 Pearson Education, Inc.
Figure 42.5b
Reptiles (Except Birds)
Pulmonary circuit
Reptiles (Except Birds)
•  Turtles, snakes, and lizards have a three-­‐chambered heart: two atria and one ventricle •  In alligators, caimans, and other crocodilians a septum divides the ventricle •  Rep?les have double circula?on, with a pulmonary circuit (lungs) and a systemic circuit Lung
capillaries
Right
systemic
aorta
Atrium
(A)
Ventricle
(V)
A
Right
V
Left
Left
systemic
aorta
Incomplete
septum
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2011 Pearson Education, Inc.
5 1/05/12 Figure 42.5c
Mammals and Birds
Pulmonary circuit
Mammals and Birds
•  Mammals and birds have a four-­‐chambered heart with two atria and two ventricles •  The le[ side of the heart pumps and receives only oxygen-­‐rich blood, while the right side receives and pumps only oxygen-­‐poor blood •  Mammals and birds are endotherms and require more O2 than ectotherms Lung
capillaries
A
Atrium
(A)
Ventricle
(V)
Right
V
Left
Systemic
capillaries
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2011 Pearson Education, Inc.
Figure 42.5
Amphibians
Pulmocutaneous circuit
Pulmonary circuit
Lung
and skin
capillaries
Atrium
(A)
Atrium
(A)
Right
Pulmonary circuit
Lung
capillaries
Lung
capillaries
Right
systemic
aorta
A
V
Right
Left
Mammals and Birds
Reptiles (Except Birds)
A
V
Left
•  The mammalian cardiovascular system meets the body’s con?nuous demand for O2 Left
systemic
aorta
Incomplete
septum
A
V
Right
Concept 42.2: Coordinated cycles of heart contrac?on drive double circula?on in mammals A
V
Left
Ventricle (V)
Systemic
capillaries
Systemic
capillaries
Systemic
capillaries
Systemic circuit
Systemic circuit
Systemic circuit
Key
Oxygen-rich blood
Oxygen-poor blood
© 2011 Pearson Education, Inc.
Mammalian Circula?on •  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 le[ atrium and is pumped through the aorta to the body ?ssues by the le[ 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 Anima?on: Path of Blood Flow in Mammals © 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
6 1/05/12 Figure 42.6
Superior vena cava
Capillaries of
head and forelimbs
Pulmonary
artery
Pulmonary
artery
Capillaries
of right lung
Aorta
Pulmonary
vein
Capillaries
of left lung
The Mammalian Heart: A Closer Look •  A closer look at the mammalian heart provides a beder understanding of double circula?on Pulmonary vein
Left atrium
Right atrium
Left ventricle
Right ventricle
Aorta
Inferior
vena cava
Capillaries of
abdominal organs
and hind limbs
© 2011 Pearson Education, Inc.
Figure 42.7
Aorta
Pulmonary artery
Pulmonary
artery
Right
atrium
Left
atrium
Semilunar
valve
Semilunar
valve
Atrioventricular
valve
Atrioventricular
valve
Right
ventricle
Figure 42.8-1
Left
ventricle
•  The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle •  The contrac?on, or pumping, phase is called systole •  The relaxa?on, or filling, phase is called diastole © 2011 Pearson Education, Inc.
Figure 42.8-2
1 Atrial and
ventricular diastole
2 Atrial systole and ventricular
diastole
1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.4
sec
7 1/05/12 Figure 42.8-3
2 Atrial systole and ventricular
diastole
•  The heart rate, also called the pulse, is the number of beats per minute •  The stroke volume is the amount of blood pumped in a single contrac?on •  The cardiac output is the volume of blood pumped into the systemic circula?on per minute and depends on both the heart rate and stroke volume 1 Atrial and
ventricular diastole
0.1
sec
0.4
sec
0.3 sec
3 Ventricular systole and atrial
diastole
© 2011 Pearson Education, Inc.
•  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 © 2011 Pearson Education, Inc.
•  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 •  Backflow of blood through a defec?ve valve causes a heart murmur © 2011 Pearson Education, Inc.
Figure 42.9-1
Maintaining the Heart s Rhythmic Beat •  Some cardiac muscle cells are self-­‐excitable, meaning they contract without any signal from the nervous system •  The sinoatrial (SA) node, or pacemaker, sets the rate and ?ming at which cardiac muscle cells contract •  Impulses that travel during the cardiac cycle can be recorded as an electrocardiogram (ECG or EKG) 1
SA node
(pacemaker)
ECG
© 2011 Pearson Education, Inc.
8 1/05/12 Figure 42.9-2
1
Figure 42.9-3
2
SA node
(pacemaker)
1
AV
node
2
SA node
(pacemaker)
ECG
AV
node
3
Bundle
branches
Heart
apex
ECG
Figure 42.9-4
1
2
SA node
(pacemaker)
AV
node
3
Bundle
branches
4
Heart
apex
•  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 Purkinje
fibers
ECG
© 2011 Pearson Education, Inc.
•  The pacemaker is regulated by two por?ons of the nervous system: the sympathe?c and parasympathe?c divisions •  The sympathe?c division speeds up the pacemaker •  The parasympathe?c division slows down the pacemaker •  The pacemaker is also regulated by hormones and temperature © 2011 Pearson Education, Inc.
Concept 42.3: Paderns of blood pressure and flow reflect the structure and arrangement of blood vessels •  The physical principles that govern movement of water in plumbing systems also influence the func?oning of animal circulatory systems © 2011 Pearson Education, Inc.
9 1/05/12 Figure 42.10
Artery
Vein
LM
Blood Vessel Structure and Func?on Red blood cells
•  A vessel s cavity is called the central lumen •  The epithelial layer that lines blood vessels is called the endothelium •  The endothelium is smooth and minimizes resistance 100 µm
Valve
Basal lamina
Endothelium
Endothelium
Smooth
muscle
Connective
tissue
Smooth
muscle
Connective
tissue
Capillary
Artery
Vein
Arteriole
15 µm
Venule
Red blood cell
LM
Capillary
© 2011 Pearson Education, Inc.
Figure 42.10a
Figure 42.10b
Valve
Basal lamina
Endothelium
Smooth
muscle
Connective
tissue
Endothelium
Capillary
Smooth
muscle
Connective
tissue
Artery
Artery
Vein
LM
Vein
Red blood cells
Arteriole
100 µm
Venule
Capillary
LM
Red blood cell
15 µm
Figure 42.10c
•  Capillaries have thin walls, the endothelium plus its basal lamina, to facilitate the exchange of materials •  Arteries and veins have an endothelium, smooth muscle, and connec?ve ?ssue •  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 ac?on © 2011 Pearson Education, Inc.
10 1/05/12 Figure 42.11
Systolic
pressure
V
ca en
va ae
e
A
A
A
r
C teri
ap o
ill les
Ve arie
nu s
le
s
Ve
in
s
a
ie
s
Diastolic
pressure
or
t
120
100
80
60
40
20
0
er
50
40
30
20
10
0
rt
Velocity
(cm/sec)
5,000
4,000
3,000
2,000
1,000
0
Pressure
(mm Hg)
•  Physical laws governing movement of fluids through pipes affect blood flow and blood pressure •  Velocity of blood flow is slowest in the capillary beds, as a result of the high resistance and large total cross-­‐
sec?onal area •  Blood flow in capillaries is necessarily slow for exchange of materials Area (cm2)
Blood Flow Velocity © 2011 Pearson Education, Inc.
Blood Pressure •  Blood flows from areas of higher pressure to areas of lower pressure •  Blood pressure is the pressure that blood exerts against the wall of a vessel •  In rigid vessels blood pressure is maintained; less rigid vessels deform and blood pressure is lost © 2011 Pearson Education, Inc.
Changes in Blood Pressure During the Cardiac Cycle •  Systolic pressure is the pressure in the arteries during ventricular systole; it is the highest pressure in the arteries •  Diastolic pressure is the pressure in the arteries during diastole; it is lower than systolic pressure •  A pulse is the rhythmic bulging of artery walls with each heartbeat © 2011 Pearson Education, Inc.
Regula+on of Blood Pressure •  Blood pressure is determined by cardiac output and peripheral resistance due to constric?on of arterioles •  Vasoconstric7on is the contrac?on of smooth muscle in arteriole walls; it increases blood pressure •  Vasodila7on is the relaxa?on of smooth muscles in the arterioles; it causes blood pressure to fall © 2011 Pearson Education, Inc.
•  Vasoconstric?on and vasodila?on help maintain adequate blood flow as the body s demands change •  Nitric oxide is a major inducer of vasodila?on •  The pep?de endothelin is an important inducer of vasoconstric?on © 2011 Pearson Education, Inc.
11 1/05/12 Figure 42.12
Blood Pressure and Gravity •  Blood pressure is generally measured for an artery in the arm at the same height as the heart •  Blood pressure for a healthy 20 year old at rest is 120 mm Hg at systole and 70 mm Hg at diastole Blood pressure reading: 120/70
1
3
2
120
120
70
Artery
closed
Sounds
audible in
stethoscope
Sounds
stop
© 2011 Pearson Education, Inc.
Figure 42.13
•  Fain?ng is caused by inadequate blood flow to the head Direction of blood flow
in vein (toward heart)
•  Animals with longer necks require a higher systolic pressure to pump blood a greater distance against gravity Valve (open)
Skeletal muscle
•  Blood is moved through veins by smooth muscle contrac?on, skeletal muscle contrac?on, and expansion of the vena cava with inhala?on Valve (closed)
•  One-­‐way valves in veins prevent backflow of blood © 2011 Pearson Education, Inc.
Capillary Func?on •  Blood flows through only 5-­‐10% of the body s capillaries at a ?me •  Capillaries in major organs are usually filled to capacity •  Blood supply varies in many other sites •  Two mechanisms regulate distribu?on of blood in capillary beds –  Contrac?on of the smooth muscle layer in the wall of an arteriole constricts the vessel –  Precapillary sphincters control flow of blood between arterioles and venules •  Blood flow is regulated by nerve impulses, hormones, and other chemicals © 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
12 1/05/12 Figure 42.14
Precapillary
sphincters
Thoroughfare
channel
Arteriole
(a) Sphincters relaxed
Arteriole
•  The exchange of substances between the blood and inters??al fluid takes place across the thin endothelial walls of the capillaries •  The difference between blood pressure and osmo?c pressure drives fluids out of capillaries at the arteriole end and into capillaries at the venule end •  Most blood proteins and all blood cells are too large to pass through the endothelium Capillaries
Venule
Venule
(b) Sphincters contracted
© 2011 Pearson Education, Inc.
Figure 42.15
Fluid Return by the Lympha?c System INTERSTITIAL
FLUID
Net fluid movement out
Body cell
Blood
pressure
Osmotic
pressure
Arterial end
of capillary
Direction of blood flow
•  The lympha7c system returns fluid that leaks out from the capillary beds •  Fluid, called lymph, reenters the circula?on directly at the venous end of the capillary bed and indirectly through the lympha?c system •  The lympha?c system drains into veins in the neck •  Valves in lymph vessels prevent the backflow of fluid Venous end
of capillary
© 2011 Pearson Education, Inc.
Figure 42.16
•  Lymph nodes are organs that filter lymph and play an important role in the body s defense •  Edema is swelling caused by disrup?ons in the flow of lymph © 2011 Pearson Education, Inc.
13 1/05/12 Concept 42.4: Blood components contribute to exchange, transport, and defense •  With open circula?on, the fluid that is pumped comes into direct contact with all cells •  The closed circulatory systems of vertebrates contain blood, a specialized connec?ve ?ssue © 2011 Pearson Education, Inc.
Blood Composi?on and Func?on •  Blood consists of several kinds of cells suspended in a liquid matrix called plasma •  The cellular elements occupy about 45% of the volume of blood © 2011 Pearson Education, Inc.
Figure 42.17
Figure 42.17a
Plasma 55%
Cellular elements 45%
Plasma 55%
Constituent
Water
Solvent for
carrying other
substances
Ions (blood
electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering,
and regulation
of membrane
permeablity
Plasma proteins
Albumin
Fibrinogen
Cell type
Major functions
Number per µL
(mm3) of blood
Functions
5,000–10,000
Defense and
immunity
Leukocytes (white blood cells)
Separated
blood
elements
Constituent
Lymphocytes
Basophils
Eosinophils
Neutrophils
Osmotic balance,
pH buffering
Monocytes
Platelets
250,000–400,000
Clotting
Immunoglobulins Defense
(antibodies)
Erythrocytes (red blood cells)
5–6 million
Substances transported by blood
Blood
clotting
Transport
of O2 and
some CO2
Nutrients
Waste products
Respiratory gases
Hormones
Major functions
Water
Solvent for
carrying other
substances
Ions (blood
electrolytes)
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate
Osmotic balance,
pH buffering,
and regulation
of membrane
permeablity
Plasma proteins
Albumin
Fibrinogen
Immunoglobulins (antibodies)
Separated
blood
elements
Osmotic balance, pH buffering
Clotting
Defense
Substances transported by blood
Nutrients
Waste products
Respiratory gases
Hormones
Figure 42.17b
Cellular elements 45%
Cell type
Leukocytes (white blood cells)
Separated
blood
elements
Number per µL
(mm3) of blood
Functions
5,000–10,000
Defense and
immunity
Lymphocytes
Basophils
Eosinophils
Neutrophils
Monocytes
Platelets
Erythrocytes (red blood cells)
250,000–400,000
5–6 million
Blood
clotting
Plasma •  Blood plasma is about 90% water •  Among its solutes are inorganic salts in the form of dissolved ions, some?mes called electrolytes •  Another important class of solutes is the plasma proteins, which influence blood pH, osmo?c pressure, and viscosity •  Various plasma proteins func?on in lipid transport, immunity, and blood clojng Transport
of O2 and
some CO2
© 2011 Pearson Education, Inc.
14 1/05/12 Cellular Elements •  Suspended in blood plasma are two types of cells –  Red blood cells (erythrocytes) transport oxygen O2 –  White blood cells (leukocytes) func?on in defense •  Platelets, a third cellular element, are fragments of cells that are involved in clojng © 2011 Pearson Education, Inc.
Erythrocytes •  Red blood cells, or erythrocytes, are by far the most numerous blood cells •  They contain hemoglobin, the iron-­‐containing protein that transports O2 •  Each molecule of hemoglobin binds up to four molecules of O2 •  In mammals, mature erythrocytes lack nuclei and mitochondria © 2011 Pearson Education, Inc.
•  Sickle-­‐cell disease is caused by abnormal hemoglobin proteins that form aggregates •  The aggregates can deform an erythrocyte into a sickle shape •  Sickled cells can rupture, or block blood vessels © 2011 Pearson Education, Inc.
Leukocytes
•  There are five major types of white blood cells, or leukocytes: monocytes, neutrophils, basophils, eosinophils, and lymphocytes •  They func?on in defense by phagocy?zing bacteria and debris or by producing an?bodies •  They are found both in and outside of the circulatory system © 2011 Pearson Education, Inc.
Blood CloCng Platelets
•  Platelets are fragments of cells and func?on in blood clojng © 2011 Pearson Education, Inc.
•  Coagula?on is the forma?on of a solid clot from liquid blood •  A cascade of complex reac?ons converts inac?ve fibrinogen to fibrin, forming a clot •  A blood clot formed within a blood vessel is called a thrombus and can block blood flow © 2011 Pearson Education, Inc.
15 1/05/12 Figure 42.18
Figure 42.18a
2
1
3
2
1
3
Collagen fibers
Collagen fibers
Platelet
plug
Platelet
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Platelet
plug
Platelet
Fibrin
clot
Red blood cell
Fibrin clot formation
Fibrin
clot
5 µm
Clotting factors from:
Platelets
Damaged cells
Plasma (factors include calcium, vitamin K)
Fibrin clot
formation
Enzymatic cascade
Prothrombin
+
Thrombin
Fibrinogen
Enzymatic cascade
Prothrombin
Fibrin
+
Thrombin
Fibrinogen
Fibrin
Figure 42.18b
Stem Cells and the Replacement of Cellular Elements Fibrin
clot
Red blood cell
5 µm
•  The cellular elements of blood wear out and are being replaced constantly •  Erythrocytes, leukocytes, and platelets all develop from a common source of stem cells in the red marrow of bones, especially ribs, vertebrae, sternum, and pelvis •  The hormone erythropoie7n (EPO) s?mulates erythrocyte produc?on when O2 delivery is low © 2011 Pearson Education, Inc.
Figure 42.19
Stem cells
(in bone marrow)
Myeloid
stem cells
Lymphoid
stem cells
B cells T cells
Erythrocytes
Lymphocytes
Monocytes
Neutrophils
Platelets
Cardiovascular Disease •  Cardiovascular diseases are disorders of the heart and the blood vessels •  Cardiovascular diseases account for more than half the deaths in the United States •  Cholesterol, a steroid, helps maintain membrane fluidity Basophils
Eosinophils
© 2011 Pearson Education, Inc.
16 1/05/12 •  Low-­‐density lipoprotein (LDL) delivers cholesterol to cells for membrane produc?on •  High-­‐density lipoprotein (HDL) scavenges cholesterol for return to the liver •  Risk for heart disease increases with a high LDL to HDL ra?o •  Inflamma?on is also a factor in cardiovascular disease © 2011 Pearson Education, Inc.
•  One type of cardiovascular disease, atherosclerosis, is caused by the buildup of plaque deposits within arteries © 2011 Pearson Education, Inc.
Figure 42.20
Lumen of artery
Endothelium
Smooth
muscle
1
LDL
Atherosclerosis, Heart AFacks, and Stroke Foam cell
Macrophage
Plaque rupture
Plaque
2
Extracellular
matrix
•  A heart aGack, or myocardial infarc?on, is the death of cardiac muscle ?ssue resul?ng from blockage of one or more coronary arteries •  Coronary arteries supply oxygen-­‐rich blood to the heart muscle •  A stroke is the death of nervous ?ssue in the brain, usually resul?ng from rupture or blockage of arteries in the head •  Angina pectoris is caused by par?al blockage of the coronary arteries and results in chest pains Smooth
muscle
cell
T lymphocyte
4
3
Fibrous cap
Cholesterol
© 2011 Pearson Education, Inc.
Figure 42.21
•  The propor?on of LDL rela?ve to HDL can be decreased by exercise, not smoking, and avoiding foods with trans fats •  Drugs called sta?ns reduce LDL levels and risk of heart adacks RESULTS
Average = 105 mg/dL
30
20
10
0
0
50
100
150
200
250
300
Plasma LDL cholesterol (mg/dL)
Individuals with two functional copies of
PCSK9 gene (control group)
Percent of individuals
•  A high LDL to HDL ra?o increases the risk of cardiovascular disease Percent of individuals
Risk Factors and Treatment of Cardiovascular Disease Average = 63 mg/dL
30
20
10
0
0
50
100
150
200
250
300
Plasma LDL cholesterol (mg/dL)
Individuals with an inactivating mutation in
one copy of PCSK9 gene
© 2011 Pearson Education, Inc.
17 1/05/12 •  Inflamma?on plays a role in atherosclerosis and thrombus forma?on •  Aspirin inhibits inflamma?on and reduces the risk of heart adacks and stroke •  Hypertension, or high blood pressure, promotes atherosclerosis and increases the risk of heart adack and stroke •  Hypertension can be reduced by dietary changes, exercise, and/or medica?on © 2011 Pearson Education, Inc.
Par?al Pressure Gradients in Gas Exchange •  A gas diffuses from a region of higher par?al pressure to a region of lower par?al pressure •  Par7al pressure is the pressure exerted by a par?cular gas in a mixture of gases •  Gases diffuse down pressure gradients in the lungs and other organs as a result of differences in par?al pressure © 2011 Pearson Education, Inc.
Respiratory Surfaces •  Animals require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium, either air or water •  Gas exchange across respiratory surfaces takes place by diffusion •  Respiratory surfaces vary by animal and can include the outer surface, skin, gills, tracheae, and lungs © 2011 Pearson Education, Inc.
Concept 42.5: Gas exchange occurs across specialized respiratory surfaces •  Gas exchange supplies O2 for cellular respira?on and disposes of CO2 © 2011 Pearson Education, Inc.
Respiratory Media •  Animals can use air or water as a source of O2, or respiratory medium •  In a given volume, there is less O2 available in water than in air •  Obtaining O2 from water requires greater efficiency than air breathing © 2011 Pearson Education, Inc.
Gills in Aqua?c Animals •  Gills are ouloldings of the body that create a large surface area for gas exchange © 2011 Pearson Education, Inc.
18 1/05/12 Figure 42.22
Figure 42.22a
Coelom
Gills
Parapodium
(functions as gill)
(a) Marine worm
Gills
Tube foot
(b) Crayfish
(c) Sea star
Parapodium (functions as gill)
(a) Marine worm
Figure 42.22b
Figure 42.22c
Coelom
Gills
Gills
Tube foot
(c) Sea star
(b) Crayfish
Figure 42.23
O2-poor blood
•  Ven7la7on moves the respiratory medium over the respiratory surface •  Aqua?c animals move through water or move water over their gills for ven?la?on •  Fish gills use a countercurrent exchange system, where blood flows in the opposite direc?on to water passing over the gills; blood is always less saturated with O2 than the water it meets Gill
arch
O2-rich blood
Lamella
Blood
vessels
Gill arch
Water
flow
Operculum
Water flow
Blood flow
Countercurrent exchange
PO2 (mm Hg) in water
Gill filaments
150 120 90 60 30
Net diffusion of O2
140 110 80 50 20
PO 2 (mm Hg)
in blood
© 2011 Pearson Education, Inc.
19 1/05/12 Figure 42.23a
Figure 42.23b
Gill
arch
O2-poor blood
O2-rich blood
Lamella
Blood
vessels
Gill arch
Water
flow
Operculum
Water flow
Blood flow
Countercurrent exchange
PO2 (mm Hg) in water
150 120 90 60 30
Gill filaments
Net diffusion of O2
Figure 42.24
140 110 80 50 20
PO2 (mm Hg)
in blood
Tracheoles Mitochondria
Muscle fiber
Tracheal Systems in Insects 2.5 µm
•  The tracheal system of insects consists of ?ny branching tubes that penetrate the body •  The tracheal tubes supply O2 directly to body cells •  The respiratory and circulatory systems are separate •  Larger insects must ven?late their tracheal system to meet O2 demands Tracheae
Body
cell
Air
sac
Air sacs
Tracheole
Trachea
External opening
Air
© 2011 Pearson Education, Inc.
Figure 42.24a
Lungs Muscle fiber
•  Lungs are an infolding of the body surface •  The circulatory system (open or closed) transports gases between the lungs and the rest of the body •  The size and complexity of lungs correlate with an animal s metabolic rate 2.5 µm
Tracheoles Mitochondria
© 2011 Pearson Education, Inc.
20 1/05/12 Figure 42.25
Mammalian Respiratory Systems: A Closer Look •  A system of branching ducts conveys air to the lungs •  Air inhaled through the nostrils is warmed, humidified, and sampled for odors •  The pharynx directs air to the lungs and food to the stomach •  Swallowing ?ps the epiglojs over the glojs in the pharynx to prevent food from entering the trachea Branch of
pulmonary vein
(oxygen-rich
blood)
Terminal
bronchiole
Branch of
pulmonary artery
(oxygen-poor
blood)
Nasal
cavity
Pharynx
Left
lung
Larynx
(Esophagus)
Alveoli
50 µm
Trachea
Right lung
Capillaries
Bronchus
Bronchiole
Diaphragm
(Heart)
Dense capillary bed
enveloping alveoli (SEM)
© 2011 Pearson Education, Inc.
Figure 42.25a
Figure 42.25b
Branch of
pulmonary vein
(oxygen-rich
blood)
Nasal
cavity
Pharynx
Terminal
bronchiole
Branch of
pulmonary artery
(oxygen-poor
blood)
Left
lung
Larynx
(Esophagus)
Trachea
Right lung
Bronchus
Alveoli
Bronchiole
Diaphragm
(Heart)
Capillaries
Figure 42.25c
50 µm
Dense capillary bed
enveloping alveoli (SEM)
•  Air passes through the pharynx, larynx, trachea, bronchi, and bronchioles to the alveoli, where gas exchange occurs •  Exhaled air passes over the vocal cords in the larynx to create sounds •  Cilia and mucus line the epithelium of the air ducts and move par?cles up to the pharynx •  This mucus escalator cleans the respiratory system and allows par?cles to be swallowed into the esophagus © 2011 Pearson Education, Inc.
21 1/05/12 •  Gas exchange takes place in alveoli, air sacs at the ?ps of bronchioles •  Oxygen diffuses through the moist film of the epithelium and into capillaries •  Carbon dioxide diffuses from the capillaries across the epithelium and into the air space © 2011 Pearson Education, Inc.
© 2011 Pearson Education, Inc.
Figure 42.26
RDS deaths
RESULTS
Surface tension (dynes/cm)
•  Alveoli lack cilia and are suscep?ble to contamina?on •  Secre?ons called surfactants coat the surface of the alveoli •  Preterm babies lack surfactant and are vulnerable to respiratory distress syndrome; treatment is provided by ar?ficial surfactants Deaths from other causes
40
Concept 42.6: Breathing ven?lates the lungs •  The process that ven?lates the lungs is breathing, the alternate inhala?on and exhala?on of air 30
20
10
0
0
800
1,600
2,400
3,200
4,000
Body mass of infant (g)
© 2011 Pearson Education, Inc.
How an Amphibian Breathes •  An amphibian such as a frog ven?lates its lungs by posi7ve pressure breathing, which forces air down the trachea © 2011 Pearson Education, Inc.
How a Bird Breathes •  Birds have eight or nine air sacs that func?on as bellows that keep air flowing through the lungs •  Air passes through the lungs in one direc?on only •  Every exhala?on completely renews the air in the lungs © 2011 Pearson Education, Inc.
22 1/05/12 Figure 42.27
Figure 42.27a
Anterior
air sacs
Posterior
air sacs
Lungs
Airflow
Air tubes
(parabronchi)
in lung
Airflow
1 mm
Posterior
air sacs
Lungs
3
Air tubes
(parabronchi)
in lung
Anterior
air sacs
2
1 mm
4
1
1 First inhalation
3 Second inhalation
2 First exhalation
4 Second exhalation
Figure 42.28
How a Mammal Breathes •  Mammals ven?late their lungs by nega7ve pressure breathing, which pulls air into the lungs •  Lung volume increases as the rib muscles and diaphragm contract •  The 7dal volume is the volume of air inhaled with each breath 1
2
Rib cage
expands.
Air
inhaled.
Rib cage gets
smaller.
Air
exhaled.
Lung
Diaphragm
© 2011 Pearson Education, Inc.
Control of Breathing in Humans •  The maximum ?dal volume is the vital capacity •  A[er exhala?on, a residual volume of air remains in the lungs © 2011 Pearson Education, Inc.
•  In humans, the main breathing control centers are in two regions of the brain, the medulla oblongata and the pons •  The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid •  The medulla adjusts breathing rate and depth to match metabolic demands •  The pons regulates the tempo © 2011 Pearson Education, Inc.
23 1/05/12 Figure 42.29
Homeostasis:
Blood pH of about 7.4
•  Sensors in the aorta and caro?d arteries monitor O2 and CO2 concentra?ons in the blood •  These sensors exert secondary control over breathing CO2 level
decreases.
Response:
Rib muscles
and diaphragm
increase rate
and depth of
ventilation.
Stimulus:
Rising level of
CO2 in tissues
lowers blood pH.
Carotid
arteries
Aorta
Sensor/control center:
Cerebrospinal fluid
Medulla
oblongata
© 2011 Pearson Education, Inc.
Concept 42.7: Adapta?ons for gas exchange include pigments that bind and transport gases •  The metabolic demands of many organisms require that the blood transport large quan??es of O2 and CO2 © 2011 Pearson Education, Inc.
Figure 42.30a
2 Alveolar
spaces
O2
Alveolar
capillaries
7 Pulmonary
arteries
3 Pulmonary
veins
6 Systemic
veins
4 Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
Partial pressure (mm Hg)
1 Inhaled air
8 Exhaled air
CO2
•  Blood arriving in the lungs has a low par?al pressure of O2 and a high par?al pressure of CO2 rela?ve to air in the alveoli •  In the alveoli, O2 diffuses into the blood and CO2 diffuses into the air •  In ?ssue capillaries, par?al pressure gradients favor diffusion of O2 into the inters??al fluids and CO2 into the blood © 2011 Pearson Education, Inc.
Figure 42.30
Alveolar
epithelial
cells
Coordina?on of Circula?on and Gas Exchange 160
PO2
PCO2
Inhaled
air
1 Inhaled air
8 Exhaled air
Alveolar
epithelial
cells
2 Alveolar
spaces
CO2
O2
Alveolar
capillaries
Exhaled
air
120
7 Pulmonary
arteries
80
3 Pulmonary
veins
40
0
1
2
3
4
5
6
7
8
6 Systemic
veins
4 Systemic
arteries
Heart
(b) Partial pressure of O2 and CO2 at different points in the
circulatory system numbered in (a)
5 Body tissue
(a) The path of respiratory gases in the circulatory
system
CO2
O2
Systemic
capillaries
5 Body tissue
(a) The path of respiratory gases in the circulatory
system
24 1/05/12 Partial pressure (mm Hg)
Figure 42.30b
PO2
PCO 2
Inhaled
air
160
Exhaled
air
120
80
40
0
1
2
3
4
5
6
7
8
Respiratory Pigments •  Respiratory pigments, proteins that transport oxygen, greatly increase the amount of oxygen that blood can carry •  Arthropods and many molluscs have hemocyanin with copper as the oxygen-­‐binding component •  Most vertebrates and some invertebrates use hemoglobin •  In vertebrates, hemoglobin is contained within erythrocytes (b) Partial pressure of O2 and CO2 at different points in the
circulatory system numbered in (a)
© 2011 Pearson Education, Inc.
Figure 42.UN01
Hemoglobin •  A single hemoglobin molecule can carry four molecules of O2, one molecule for each iron containing heme group •  The hemoglobin dissocia?on curve shows that a small change in the par?al pressure of oxygen can result in a large change in delivery of O2 •  CO2 produced during cellular respira?on lowers blood pH and decreases the affinity of hemoglobin for O2; this is called the Bohr shiM Iron
Heme
Hemoglobin
© 2011 Pearson Education, Inc.
O2 unloaded
to tissues
at rest
80
O2 unloaded
to tissues
during exercise
60
40
20
0
0
20
40
60
Tissues during Tissues
at rest
exercise
PO2 (mm Hg)
80
100
Lungs
(a) PO2 and hemoglobin dissociation at pH 7.4
100
pH 7.4
80
pH 7.2
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration)
60
40
20
0
0
20
40
60
80
PO2 (mm Hg)
100
O2 saturation of hemoglobin (%)
100
Figure 42.31a
O2 saturation of hemoglobin (%)
O2 saturation of hemoglobin (%)
Figure 42.31
100
O2 unloaded
to tissues
at rest
80
O2 unloaded
to tissues
during exercise
60
40
20
0
0
20
40
60
80
100
(b) pH and hemoglobin dissociation
Tissues during Tissues
at rest
exercise
PO2 (mm Hg)
Lungs
(a) PO2 and hemoglobin dissociation at pH 7.4
25 1/05/12 O2 saturation of hemoglobin (%)
Figure 42.31b
100
Carbon Dioxide Transport pH 7.4
80
pH 7.2
Hemoglobin
retains less
O2 at lower pH
(higher CO2
concentration)
60
40
•  Hemoglobin also helps transport CO2 and assists in buffering the blood •  CO2 from respiring cells diffuses into the blood and is transported either in blood plasma, bound to hemoglobin, or as bicarbonate ions (HCO3–) 20
0
Anima?on: O2 from Blood to Tissues Anima?on: CO2 from Tissues to Blood 0
20
40
60
80
100
Anima?on: CO2 from Blood to Lungs PO2 (mm Hg)
Anima?on: O2 from Lungs to Blood (b) pH and hemoglobin dissociation
© 2011 Pearson Education, Inc.
Figure 42.32
Figure 42.32a
Body tissue
Body tissue
CO2 transport
from tissues
CO2 produced
CO2 produced
Interstitial
CO2
fluid
Plasma
CO2
within capillary
Capillary
wall
CO2 transport
from tissues
Interstitial
CO2
fluid
CO2
H 2O
Red
blood
cell
H2CO3
Hb
Carbonic
acid
HCO3- +
Bicarbonate
HCO3-
HCO3
H2CO3
Plasma
CO2
within capillary
Capillary
wall
CO2
To lungs
H 2O
CO2 transport
to lungs
-
HCO3- +
Hemoglobin (Hb)
picks up
CO2 and H+.
H+
Red
blood
cell
H+
Hb
Hemoglobin
releases
CO2 and H+.
H2CO3
Hb
Carbonic
acid
HCO3- +
Bicarbonate
H 2O
CO2
Hemoglobin (Hb)
picks up
CO2 and H+.
H+
CO2
HCO3-
CO2
To lungs
CO2
Alveolar space in lung
Figure 42.32b
To lungs
CO2 transport
to lungs
HCO3HCO3- +
H2CO3
H+
Hb
Hemoglobin
releases
CO2 and H+.
H 2O
CO2
CO2
Respiratory Adapta?ons of Diving Mammals •  Diving mammals have evolu?onary adapta?ons that allow them to perform extraordinary feats –  For example, Weddell seals in Antarc?ca can remain underwater for 20 minutes to an hour –  For example, elephant seals can dive to 1,500 m and remain underwater for 2 hours •  These animals have a high blood to body volume ra?o CO2
CO2
Alveolar space in lung
© 2011 Pearson Education, Inc.
26 1/05/12 Figure 42.UN02
Inhaled air
Exhaled air
Alveolar
epithelial
cells
•  Deep-­‐diving air breathers stockpile O2 and deplete it slowly •  Diving mammals can store oxygen in their muscles in myoglobin proteins •  Diving mammals also conserve oxygen by Alveolar
spaces
CO2
O2
Alveolar
capillaries
Pulmonary
arteries
Pulmonary
veins
Systemic
veins
–  Changing their buoyancy to glide passively –  Decreasing blood supply to muscles –  Deriving ATP in muscles from fermenta?on once oxygen is depleted Systemic
arteries
Heart
CO2
O2
Systemic
capillaries
Body tissue
© 2011 Pearson Education, Inc.
Figure 42.UN04
O2 saturation of
hemoglobin (%)
Figure 42.UN03
100
80
60
Fetus
Mother
40
20
0
0 20 40 60 80 100
PO2 (mm Hg)
27