Circulation and Gas Exchange

Circulation and Gas Exchange
Chapter 42 Circulation and Gas Exchange

Overview: Trading Places
Every organism must exchange materials with its environment Exchanges ultimately occur at the cellular level by crossing the plasma membrane In unicellular organisms, these exchanges occur directly with the environment © 2011 Pearson Education, Inc.

Gills are an example of a specialized exchange system in animals
For most cells making up multicellular 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 functionally related in most animals © 2011 Pearson Education, Inc.

Figure 42.1 Figure 42.1 How does a feathery fringe help this animal survive?

Concept 42.1: Circulatory systems link exchange surfaces with cells throughout the body
Diffusion time is proportional 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 Cavities
Some animals lack a circulatory system Some cnidarians, such as jellies, have elaborate gastrovascular cavities A gastrovascular cavity functions in both digestion and distribution 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 ratio © 2011 Pearson Education, Inc.

(a) The moon jelly Aurelia, a cnidarian
Figure 42.2 Circular canal Mouth Gastrovascular cavity Mouth Figure 42.2 Internal transport in gastrovascular cavities. Pharynx Radial canals 5 cm 2 mm (a) The moon jelly Aurelia, a cnidarian (b) The planarian Dugesia, a flatworm

(a) The moon jelly Aurelia, a cnidarian
Figure 42.2a Circular canal Mouth Figure 42.2 Internal transport in gastrovascular cavities. Radial canals 5 cm (a) The moon jelly Aurelia, a cnidarian

(b) The planarian Dugesia, a flatworm
Figure 42.2b Gastrovascular cavity Mouth Figure 42.2 Internal transport in gastrovascular cavities. Pharynx 2 mm (b) The planarian Dugesia, a flatworm

Evolutionary Variation in Circulatory Systems
A circulatory system minimizes the diffusion distance in animals with many cell layers © 2011 Pearson Education, Inc.

General Properties of Circulatory Systems
A circulatory system has A circulatory fluid A set of interconnecting 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 distinction between blood and interstitial fluid, and this general body fluid is called hemolymph © 2011 Pearson Education, Inc.

(a) An open circulatory system (b) A closed circulatory system
Figure 42.3 (a) An open circulatory system (b) A closed circulatory system Heart Heart Interstitial fluid Hemolymph in sinuses surrounding organs Blood Small branch vessels in each organ Pores Dorsal vessel (main heart) Auxiliary hearts Figure 42.3 Open and closed circulatory systems. Tubular heart Ventral vessels

(a) An open circulatory system
Figure 42.3a (a) An open circulatory system Heart Hemolymph in sinuses surrounding organs Pores Figure 42.3 Open and closed circulatory systems. Tubular heart

Annelids, cephalopods, and vertebrates have closed circulatory systems
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 Annelids, cephalopods, and vertebrates have closed circulatory systems © 2011 Pearson Education, Inc.

Heart Dorsal vessel (main heart) Auxiliary hearts
Figure 42.3b (b) A closed circulatory system Heart Interstitial fluid Blood Small branch vessels in each organ Dorsal vessel (main heart) Auxiliary hearts Figure 42.3 Open and closed circulatory systems. Ventral vessels

Organization 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 interstitial fluid Venules converge into veins and return blood from capillaries to the heart © 2011 Pearson Education, Inc. © 2011 Pearson Education, Inc.

Vertebrate hearts contain two or more chambers
Arteries and veins are distinguished by the direction 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.

Single Circulation Bony fishes, rays, and sharks have single circulation with a two-chambered heart In single circulation, blood leaving the heart passes through two capillary beds before returning © 2011 Pearson Education, Inc.

(a) Single circulation (b) Double circulation
Figure 42.4 (a) Single circulation (b) Double circulation Pulmonary circuit Gill capillaries Lung capillaries Artery Heart: A A Atrium (A) V V Ventricle (V) Right Left Vein Figure 42.4 Single and double circulation in vertebrates. Systemic capillaries Body capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood

(a) Single circulation
Figure 42.4a (a) Single circulation Gill capillaries Artery Heart: Atrium (A) Ventricle (V) Figure 42.4 Single and double circulation in vertebrates. Vein Body capillaries Key Oxygen-rich blood Oxygen-poor blood

Double Circulation Amphibian, reptiles, and mammals have double circulation Oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart © 2011 Pearson Education, Inc.

(b) Double circulation
Figure 42.4b (b) Double circulation Pulmonary circuit Lung capillaries A A V V Right Left Figure 42.4 Single and double circulation in vertebrates. Systemic capillaries Systemic circuit Key Oxygen-rich blood Oxygen-poor blood

Oxygen-rich blood delivers oxygen through the systemic circuit
In reptiles 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 circulation maintains higher blood pressure in the organs than does single circulation © 2011 Pearson Education, Inc.

Adaptations of Double Circulatory Systems
Hearts vary in different vertebrate groups © 2011 Pearson Education, Inc.

Amphibians 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 © 2011 Pearson Education, Inc.

Amphibians Key Pulmocutaneous circuit Lung and skin capillaries Atrium
Figure 42.5a Amphibians Pulmocutaneous circuit Lung and skin capillaries Atrium (A) Atrium (A) Figure 42.5 Exploring: Double Circulation in Vertebrates Right Left Ventricle (V) Key Systemic capillaries Oxygen-rich blood Oxygen-poor blood Systemic 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 Reptiles have double circulation, with a pulmonary circuit (lungs) and a systemic circuit © 2011 Pearson Education, Inc.

Reptiles (Except Birds)
Figure 42.5b Reptiles (Except Birds) Pulmonary circuit Lung capillaries Right systemic aorta Left systemic aorta Atrium (A) A Incomplete septum V Ventricle (V) Right Left Figure 42.5 Exploring: Double Circulation in Vertebrates Key Systemic capillaries Oxygen-rich blood Oxygen-poor blood Systemic circuit

Mammals and Birds Mammals and birds have a four-chambered heart with two atria and two ventricles The left 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 © 2011 Pearson Education, Inc.

Mammals and Birds Pulmonary circuit Lung capillaries Atrium (A) A V
Figure 42.5c Mammals and Birds Pulmonary circuit Lung capillaries Atrium (A) A V Ventricle (V) Right Left Figure 42.5 Exploring: Double Circulation in Vertebrates Key Systemic capillaries Oxygen-rich blood Oxygen-poor blood Systemic circuit

Reptiles (Except Birds) Mammals and Birds
Figure 42.5 Amphibians Reptiles (Except Birds) Mammals and Birds Pulmocutaneous circuit Pulmonary circuit Pulmonary circuit Lung and skin capillaries Lung capillaries Lung capillaries Right systemic aorta Left systemic aorta Atrium (A) Atrium (A) A A A A V V Incomplete septum Incomplete septum V V Right Left Right Left Right Left Ventricle (V) Systemic capillaries Systemic capillaries Systemic capillaries Figure 42.5 Exploring: Double Circulation in Vertebrates Systemic circuit Systemic circuit Systemic circuit Key Oxygen-rich blood Oxygen-poor blood

Concept 42.2: Coordinated cycles of heart contraction drive double circulation in mammals
The mammalian cardiovascular system meets the body’s continuous demand for O2 © 2011 Pearson Education, Inc.

Mammalian Circulation
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 © 2011 Pearson Education, Inc.

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 Animation: Path of Blood Flow in Mammals © 2011 Pearson Education, Inc.

Animation: Path of Blood Flow in Mammals
Right-click slide / select “Play” © 2011 Pearson Education, Inc.

Superior vena cava Capillaries of head and forelimbs Pulmonary
Figure 42.6 Superior vena cava Capillaries of head and forelimbs Pulmonary artery Pulmonary artery Capillaries of right lung Aorta Capillaries of left lung Pulmonary vein Pulmonary vein Left atrium Figure 42.6 The mammalian cardiovascular system: an overview. Right atrium Left ventricle Right ventricle Aorta Inferior vena cava Capillaries of abdominal organs and hind limbs

The Mammalian Heart: A Closer Look
A closer look at the mammalian heart provides a better understanding of double circulation © 2011 Pearson Education, Inc.

Pulmonary artery Aorta Pulmonary artery Right atrium Left atrium
Figure 42.7 Pulmonary artery Aorta Pulmonary artery Right atrium Left atrium Semilunar valve Semilunar valve Figure 42.7 The mammalian heart: a closer look. Atrioventricular valve Atrioventricular valve Right ventricle Left ventricle

The contraction, or pumping, phase is called systole
The heart contracts and relaxes in a rhythmic cycle called the cardiac cycle The contraction, or pumping, phase is called systole The relaxation, or filling, phase is called diastole © 2011 Pearson Education, Inc.

Atrial and ventricular diastole 0.4 sec 1 Figure 42.8-1
Figure 42.8 The cardiac cycle. 0.4 sec

Atrial systole and ventricular diastole
Figure Atrial systole and ventricular diastole 2 Atrial and ventricular diastole 1 0.1 sec Figure 42.8 The cardiac cycle. 0.4 sec

Atrial systole and ventricular diastole
Figure Atrial systole and ventricular diastole 2 Atrial and ventricular diastole 1 0.1 sec Figure 42.8 The cardiac cycle. 0.3 sec 0.4 sec Ventricular systole and atrial diastole 3

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 contraction The cardiac output is the volume of blood pumped into the systemic circulation per minute and depends on both the heart rate and stroke volume © 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.

Backflow of blood through a defective valve causes a heart murmur
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 defective valve causes a heart murmur © 2011 Pearson Education, Inc.

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 timing at which cardiac muscle cells contract Impulses that travel during the cardiac cycle can be recorded as an electrocardiogram (ECG or EKG) © 2011 Pearson Education, Inc.

SA node (pacemaker) ECG 1 Figure 42.9-1
Figure 42.9 The control of heart rhythm. ECG

AV SA node node (pacemaker) ECG 1 2 Figure 42.9-2
Figure 42.9 The control of heart rhythm. ECG

AV SA node node (pacemaker) Bundle branches Heart apex ECG 1 2 3
Figure 1 2 3 AV node SA node (pacemaker) Bundle branches Heart apex Figure 42.9 The control of heart rhythm. ECG

AV SA node node (pacemaker) Bundle Purkinje branches fibers Heart apex
Figure 1 2 3 4 AV node SA node (pacemaker) Bundle branches Purkinje fibers Heart apex Figure 42.9 The control of heart rhythm. ECG

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 © 2011 Pearson Education, Inc.

The sympathetic division speeds up the pacemaker
The pacemaker is regulated by two portions of the nervous system: the sympathetic and parasympathetic divisions The sympathetic division speeds up the pacemaker The parasympathetic division slows down the pacemaker The pacemaker is also regulated by hormones and temperature © 2011 Pearson Education, Inc.

Concept 42.3: Patterns 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 functioning of animal circulatory systems © 2011 Pearson Education, Inc.

Blood Vessel Structure and Function
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 © 2011 Pearson Education, Inc.

Artery Vein LM Red blood cells 100 m Valve Basal lamina Endothelium
Figure 42.10 Artery Vein LM Red blood cells 100 m Valve Basal lamina Endothelium Endothelium Smooth muscle Smooth muscle Connective tissue Capillary Connective tissue Artery Vein Figure The structure of blood vessels. Arteriole Venule 15 m Red blood cell Capillary LM

Valve Basal lamina Endothelium Endothelium Smooth Smooth muscle muscle
Figure 42.10a Valve Basal lamina Endothelium Endothelium Smooth muscle Smooth muscle Connective tissue Capillary Connective tissue Artery Vein Figure The structure of blood vessels. Arteriole Venule

Artery Vein LM Red blood cells 100 m Figure 42.10b
Figure The structure of blood vessels.

15 m Red blood cell Capillary LM Figure 42.10c
Figure The structure of blood vessels.

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 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 © 2011 Pearson Education, Inc.

Blood Flow Velocity 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-sectional area Blood flow in capillaries is necessarily slow for exchange of materials © 2011 Pearson Education, Inc.

Area (cm2) Velocity (cm/sec) Pressure (mm Hg)
Figure 42.11 5,000 4,000 Area (cm2) 3,000 2,000 1,000 50 40 Velocity (cm/sec) 30 20 10 Figure The interrelationship of cross-sectional area of blood vessels, blood flow velocity, and blood pressure. 120 Systolic pressure 100 Pressure (mm Hg) 80 60 Diastolic pressure 40 20 Aorta Arteries Veins Venae cavae Venules Arterioles Capillaries

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.

Regulation of Blood Pressure
Blood pressure is determined by cardiac output and peripheral resistance due to constriction of arterioles Vasoconstriction is the contraction of smooth muscle in arteriole walls; it increases blood pressure Vasodilation is the relaxation of smooth muscles in the arterioles; it causes blood pressure to fall © 2011 Pearson Education, Inc.

Nitric oxide is a major inducer of vasodilation
Vasoconstriction and vasodilation help maintain adequate blood flow as the body’s demands change Nitric oxide is a major inducer of vasodilation The peptide endothelin is an important inducer of vasoconstriction © 2011 Pearson Education, Inc.

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 © 2011 Pearson Education, Inc.

Blood pressure reading: 120/70
Figure 42.12 Blood pressure reading: 120/70 1 2 3 120 120 70 Figure Measurement of blood pressure. Artery closed Sounds audible in stethoscope Sounds stop

Fainting is caused by inadequate blood flow to the head
Animals with longer necks require a higher systolic pressure to pump blood a greater distance against gravity Blood is moved through veins by smooth muscle contraction, skeletal muscle contraction, and expansion of the vena cava with inhalation One-way valves in veins prevent backflow of blood © 2011 Pearson Education, Inc.

Direction of blood flow in vein (toward heart) Valve (open)
Figure 42.13 Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle Figure Blood flow in veins. Valve (closed)

Capillary Function Blood flows through only 510% of the body’s capillaries at a time Capillaries in major organs are usually filled to capacity Blood supply varies in many other sites © 2011 Pearson Education, Inc.

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 Blood flow is regulated by nerve impulses, hormones, and other chemicals © 2011 Pearson Education, Inc.

(a) Sphincters relaxed
Figure 42.14 Precapillary sphincters Thoroughfare channel Capillaries Venule Arteriole (a) Sphincters relaxed Figure Blood flow in capillary beds. Arteriole Venule (b) Sphincters contracted

The 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 Most blood proteins and all blood cells are too large to pass through the endothelium © 2011 Pearson Education, Inc.

Direction of blood flow
Figure 42.15 INTERSTITIAL FLUID Body cell Net fluid movement out Blood pressure Osmotic pressure Figure Fluid exchange between capillaries and the interstitial fluid. Arterial end of capillary Venous end of capillary Direction of blood flow

Fluid Return by the Lymphatic System
The lymphatic system returns fluid that leaks out from the capillary beds Fluid, called lymph, reenters the circulation directly at the venous end of the capillary bed and indirectly through the lymphatic system The lymphatic system drains into veins in the neck Valves in lymph vessels prevent the backflow of fluid © 2011 Pearson Education, Inc.

Edema is swelling caused by disruptions in the flow of lymph
Lymph nodes are organs that filter lymph and play an important role in the body’s defense Edema is swelling caused by disruptions in the flow of lymph © 2011 Pearson Education, Inc.

Figure 42.16 Figure Human lymph nodes and vessels.

Concept 42.4: Blood components contribute to exchange, transport, and defense
With open circulation, the fluid that is pumped comes into direct contact with all cells The closed circulatory systems of vertebrates contain blood, a specialized connective tissue © 2011 Pearson Education, Inc.

Blood Composition and Function
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 The composition of mammalian blood.
Plasma 55% Cellular elements 45% Constituent Major functions Cell type Number per L (mm3) of blood Functions Water Solvent for carrying other substances Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Ions (blood electrolytes) Osmotic balance, pH buffering, and regulation of membrane permeablity Separated blood elements Lymphocytes Basophils Sodium Potassium Calcium Magnesium Chloride Bicarbonate Eosinophils Plasma proteins Monocytes Neutrophils Albumin Osmotic balance, pH buffering Platelets 250,000–400,000 Blood clotting Fibrinogen Figure The composition of mammalian blood. Clotting Immunoglobulins (antibodies) Defense Erythrocytes (red blood cells) 5–6 million Transport of O2 and some CO2 Substances transported by blood Nutrients Waste products Respiratory gases Hormones

Osmotic balance, pH buffering Fibrinogen Clotting
Figure 42.17a Plasma 55% Constituent Major functions Water Solvent for carrying other substances Ions (blood electrolytes) Osmotic balance, pH buffering, and regulation of membrane permeablity Separated blood elements Sodium Potassium Calcium Magnesium Chloride Bicarbonate Figure The composition of mammalian blood. Plasma proteins Albumin Osmotic balance, pH buffering Fibrinogen Clotting Immunoglobulins (antibodies) Defense Substances transported by blood Nutrients Waste products Respiratory gases Hormones

Leukocytes (white blood cells) 5,000–10,000 Defense and immunity
Figure 42.17b Cellular elements 45% Number per L (mm3) of blood Cell type Functions Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Separated blood elements Lymphocytes Basophils Eosinophils Monocytes Figure The composition of mammalian blood. Neutrophils Platelets 250,000–400,000 Blood clotting Erythrocytes (red blood cells) 5–6 million Transport of O2 and some CO2

Plasma Blood plasma is about 90% water
Among its solutes are inorganic salts in the form of dissolved ions, sometimes called electrolytes Another important class of solutes is the plasma proteins, which influence blood pH, osmotic pressure, and viscosity Various plasma proteins function in lipid transport, immunity, and blood clotting © 2011 Pearson Education, Inc.

Cellular Elements Suspended in blood plasma are two types of cells
Red blood cells (erythrocytes) transport oxygen O2 White blood cells (leukocytes) function in defense Platelets, a third cellular element, are fragments of cells that are involved in clotting © 2011 Pearson Education, Inc. © 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.

The aggregates can deform an erythrocyte into a sickle shape
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 function in defense by phagocytizing bacteria and debris or by producing antibodies They are found both in and outside of the circulatory system © 2011 Pearson Education, Inc.

Blood Clotting Coagulation is the formation of a solid clot from liquid blood A cascade of complex reactions converts inactive 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.

 Collagen fibers Platelet plug Fibrin clot Platelet Red blood cell
Figure 42.18 1 2 3 Collagen fibers Platelet plug Fibrin clot Platelet Red blood cell 5 m Clotting factors from: Fibrin clot formation Platelets Damaged cells Plasma (factors include calcium, vitamin K) Figure Blood clotting. Enzymatic cascade  Prothrombin Thrombin Fibrinogen Fibrin

Clotting factors from: Fibrin clot formation Platelets Damaged cells
Figure 42.18a 1 2 3 Collagen fibers Platelet plug Fibrin clot Platelet Clotting factors from: Fibrin clot formation Platelets Damaged cells Plasma (factors include calcium, vitamin K) Figure Blood clotting. Enzymatic cascade  Prothrombin Thrombin Fibrinogen Fibrin

Fibrin clot Red blood cell 5 m Figure 42.18b
Figure Blood clotting. Fibrin clot Red blood cell 5 m

Stem Cells and the Replacement of Cellular Elements
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 erythropoietin (EPO) stimulates erythrocyte production when O2 delivery is low © 2011 Pearson Education, Inc.

Stem cells (in bone marrow) Myeloid stem cells Lymphoid stem cells
Figure 42.19 Stem cells (in bone marrow) Myeloid stem cells Lymphoid stem cells B cells T cells Figure Differentiation of blood cells. Erythrocytes Basophils Neutrophils Lymphocytes Monocytes Eosinophils 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 © 2011 Pearson Education, Inc.

Risk for heart disease increases with a high LDL to HDL ratio
Low-density lipoprotein (LDL) delivers cholesterol to cells for membrane production High-density lipoprotein (HDL) scavenges cholesterol for return to the liver Risk for heart disease increases with a high LDL to HDL ratio Inflammation is also a factor in cardiovascular disease © 2011 Pearson Education, Inc.

Atherosclerosis, Heart Attacks, and Stroke
One type of cardiovascular disease, atherosclerosis, is caused by the buildup of plaque deposits within arteries © 2011 Pearson Education, Inc.

Lumen of artery Plaque Endothelium Smooth muscle 1 2 Smooth muscle
Figure 42.20 Lumen of artery Plaque Endothelium Smooth muscle 1 2 Smooth muscle cell LDL Foam cell Extra- cellular matrix Macrophage T lymphocyte Plaque rupture 3 4 Figure Atherosclerosis. Fibrous cap Cholesterol

Coronary arteries supply oxygen-rich blood to the heart muscle
A heart attack, or myocardial infarction, is the death of cardiac muscle tissue resulting 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 tissue in the brain, usually resulting from rupture or blockage of arteries in the head Angina pectoris is caused by partial blockage of the coronary arteries and results in chest pains © 2011 Pearson Education, Inc.

Risk Factors and Treatment of Cardiovascular Disease
A high LDL to HDL ratio increases the risk of cardiovascular disease The proportion of LDL relative to HDL can be decreased by exercise, not smoking, and avoiding foods with trans fats Drugs called statins reduce LDL levels and risk of heart attacks © 2011 Pearson Education, Inc.

Percent of individuals Percent of individuals
Figure 42.21 RESULTS Average  105 mg/dL Average  63 mg/dL 30 30 20 20 Percent of individuals Percent of individuals 10 10 50 100 150 200 250 300 50 100 150 200 250 300 Plasma LDL cholesterol (mg/dL) Figure Inquiry: Can inactivating a liver enzyme lower plasma LDL levels? Plasma LDL cholesterol (mg/dL) Individuals with two functional copies of PCSK9 gene (control group) Individuals with an inactivating mutation in one copy of PCSK9 gene

Inflammation plays a role in atherosclerosis and thrombus formation
Aspirin inhibits inflammation and reduces the risk of heart attacks and stroke Hypertension, or high blood pressure, promotes atherosclerosis and increases the risk of heart attack and stroke Hypertension can be reduced by dietary changes, exercise, and/or medication © 2011 Pearson Education, Inc.

Concept 42.5: Gas exchange occurs across specialized respiratory surfaces
Gas exchange supplies O2 for cellular respiration and disposes of CO2 © 2011 Pearson Education, Inc.

Partial Pressure Gradients in Gas Exchange
A gas diffuses from a region of higher partial pressure to a region of lower partial pressure Partial pressure is the pressure exerted by a particular gas in a mixture of gases Gases diffuse down pressure gradients in the lungs and other organs as a result of differences in partial pressure © 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.

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.

Gills in Aquatic Animals
Gills are outfoldings of the body that create a large surface area for gas exchange © 2011 Pearson Education, Inc.

Coelom Gills Gills Tube foot Parapodium (functions as gill)
Figure 42.22 Coelom Gills Gills Figure Diversity in the structure of gills, external body surfaces that function in gas exchange. Tube foot Parapodium (functions as gill) (a) Marine worm (b) Crayfish (c) Sea star

Parapodium (functions as gill)
Figure 42.22a Figure Diversity in the structure of gills, external body surfaces that function in gas exchange. Parapodium (functions as gill) (a) Marine worm

Gills (b) Crayfish Figure 42.22b
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange. Gills (b) Crayfish

Coelom Gills Tube foot (c) Sea star Figure 42.22c
Figure Diversity in the structure of gills, external body surfaces that function in gas exchange. Gills Tube foot (c) Sea star

Ventilation moves the respiratory medium over the respiratory surface
Aquatic animals move through water or move water over their gills for ventilation Fish gills use a countercurrent exchange system, where blood flows in the opposite direction to water passing over the gills; blood is always less saturated with O2 than the water it meets © 2011 Pearson Education, Inc.

Countercurrent exchange PO (mm Hg) in water 2
Figure 42.23 O2-poor blood Gill arch O2-rich blood Lamella Blood vessels Gill arch Water flow Operculum Water flow Blood flow Countercurrent exchange Figure The structure and function of fish gills. PO (mm Hg) in water 2 150 120 90 60 30 Gill filaments Net diffusion of O2 140 110 80 50 20 PO (mm Hg) in blood 2

Gill arch Blood vessels Gill arch Water flow Operculum Gill filaments
Figure 42.23a Gill arch Blood vessels Gill arch Water flow Operculum Figure The structure and function of fish gills. Gill filaments

Countercurrent exchange PO (mm Hg) in water
Figure 42.23b O2-poor blood O2-rich blood Lamella Water flow Blood flow Figure The structure and function of fish gills. Countercurrent exchange PO (mm Hg) in water 2 150 120 90 60 30 Net diffusion of O2 140 110 80 50 20 PO (mm Hg) in blood 2

Tracheal Systems in Insects
The tracheal system of insects consists of tiny 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 ventilate their tracheal system to meet O2 demands © 2011 Pearson Education, Inc.

Tracheoles Mitochondria Muscle fiber 2.5 m Body cell Tracheae Air sac
Figure 42.24 Tracheoles Mitochondria Muscle fiber 2.5 m Body cell Tracheae Air sac Tracheole Figure Tracheal systems. Air sacs Trachea Air External opening

Tracheoles Mitochondria Muscle fiber 2.5 m Figure 42.24a
Figure Tracheal systems. 2.5 m

Lungs 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 © 2011 Pearson Education, Inc.

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 tips the epiglottis over the glottis in the pharynx to prevent food from entering the trachea © 2011 Pearson Education, Inc.

enveloping alveoli (SEM)
Figure 42.25 Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary artery (oxygen-poor blood) Terminal bronchiole Nasal cavity Pharynx Left lung Larynx (Esophagus) Alveoli Trachea 50 m Right lung Capillaries Bronchus Figure The mammalian respiratory system. Bronchiole Diaphragm (Heart) Dense capillary bed enveloping alveoli (SEM)

Nasal cavity Pharynx Left Larynx lung (Esophagus) Trachea Right lung
Figure 42.25a Nasal cavity Pharynx Left lung Larynx (Esophagus) Trachea Right lung Figure The mammalian respiratory system. Bronchus Bronchiole Diaphragm (Heart)

Branch of pulmonary vein (oxygen-rich blood) Branch of
Figure 42.25b Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary artery (oxygen-poor blood) Terminal bronchiole Figure The mammalian respiratory system. Alveoli Capillaries

enveloping alveoli (SEM)
Figure 42.25c 50 m Figure The mammalian respiratory system. Dense capillary bed enveloping alveoli (SEM)

Exhaled air passes over the vocal cords in the larynx to create sounds
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 particles up to the pharynx This “mucus escalator” cleans the respiratory system and allows particles to be swallowed into the esophagus © 2011 Pearson Education, Inc.

Gas exchange takes place in alveoli, air sacs at the tips 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.

Alveoli lack cilia and are susceptible to contamination
Secretions called surfactants coat the surface of the alveoli Preterm babies lack surfactant and are vulnerable to respiratory distress syndrome; treatment is provided by artificial surfactants © 2011 Pearson Education, Inc.

Deaths from other causes
Figure 42.26 RESULTS RDS deaths Deaths from other causes 40 30 Surface tension (dynes/cm) 20 10 Figure Inquiry: What causes respiratory distress syndrome? 800 1,600 2,400 3,200 4,000 Body mass of infant (g)

Concept 42.6: Breathing ventilates the lungs
The process that ventilates the lungs is breathing, the alternate inhalation and exhalation of air © 2011 Pearson Education, Inc.

How an Amphibian Breathes
An amphibian such as a frog ventilates its lungs by positive pressure breathing, which forces air down the trachea © 2011 Pearson Education, Inc.

How a Bird Breathes Birds have eight or nine air sacs that function as bellows that keep air flowing through the lungs Air passes through the lungs in one direction only Every exhalation completely renews the air in the lungs © 2011 Pearson Education, Inc.

Anterior air sacs Posterior air sacs Airflow Air tubes (parabronchi)
Figure 42.27 Anterior air sacs Posterior air sacs Lungs Airflow Air tubes (parabronchi) in lung 1 mm Lungs Posterior air sacs Anterior air sacs 3 Figure The avian respiratory system. 2 4 1 1 First inhalation 3 Second inhalation 2 First exhalation 4 Second exhalation

Airflow Air tubes (parabronchi) in lung 1 mm Figure 42.27a
Figure The avian respiratory system. 1 mm

How a Mammal Breathes Mammals ventilate their lungs by negative pressure breathing, which pulls air into the lungs Lung volume increases as the rib muscles and diaphragm contract The tidal volume is the volume of air inhaled with each breath © 2011 Pearson Education, Inc.

1 2 Rib cage expands. Air inhaled. Rib cage gets smaller. Air exhaled.
Figure 42.28 1 2 Rib cage expands. Air inhaled. Rib cage gets smaller. Air exhaled. Lung Figure Negative pressure breathing. Diaphragm

The maximum tidal volume is the vital capacity
After exhalation, a residual volume of air remains in the lungs © 2011 Pearson Education, Inc.

Control of Breathing in Humans
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.

These sensors exert secondary control over breathing
Sensors in the aorta and carotid arteries monitor O2 and CO2 concentrations in the blood These sensors exert secondary control over breathing © 2011 Pearson Education, Inc.

Sensor/control center: Aorta Cerebrospinal fluid
Figure 42.29 Homeostasis: Blood pH of about 7.4 CO2 level decreases. Stimulus: Rising level of CO2 in tissues lowers blood pH. Response: Rib muscles and diaphragm increase rate and depth of ventilation. Carotid arteries Figure Homeostatic control of breathing. Sensor/control center: Aorta Cerebrospinal fluid Medulla oblongata

Concept 42.7: Adaptations for gas exchange include pigments that bind and transport gases
The metabolic demands of many organisms require that the blood transport large quantities of O2 and CO2 © 2011 Pearson Education, Inc.

Coordination of Circulation and Gas Exchange
Blood arriving in the lungs has a low partial pressure of O2 and a high partial pressure of CO2 relative to air in the alveoli In the alveoli, O2 diffuses into the blood and CO2 diffuses into the air In tissue capillaries, partial pressure gradients favor diffusion of O2 into the interstitial fluids and CO2 into the blood © 2011 Pearson Education, Inc.

Figure 42.30 8 Exhaled air 1 Inhaled air PO 2 Inhaled air PCO 2 2 Alveolar spaces 160 Alveolar epithelial cells Exhaled air CO2 O2 Alveolar capillaries 120 Partial pressure (mm Hg) 7 Pulmonary arteries 3 Pulmonary veins 80 40 6 Systemic veins 4 Systemic arteries Heart 1 2 3 4 5 6 7 8 (b) Partial pressure of O2 and CO2 at different points in the circulatory system numbered in (a) Figure Loading and unloading of respiratory gases. Systemic capillaries CO2 O2 5 Body tissue (a) The path of respiratory gases in the circulatory system

(a) The path of respiratory gases in the circulatory system
Figure 42.30a 8 Exhaled air 1 Inhaled air 2 Alveolar spaces Alveolar epithelial cells CO2 O2 Alveolar capillaries 7 Pulmonary arteries 3 Pulmonary veins 6 Systemic veins 4 Systemic arteries Heart Figure Loading and unloading of respiratory gases. Systemic capillaries CO2 O2 5 Body tissue (a) The path of respiratory gases in the circulatory system

Partial pressure (mm Hg)
Figure 42.30b PO 2 Inhaled air PCO 2 160 Exhaled air 120 Partial pressure (mm Hg) 80 40 Figure Loading and unloading of respiratory gases. 1 2 3 4 5 6 7 8 (b) Partial pressure of O2 and CO2 at different points in the circulatory system numbered in (a)

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 © 2011 Pearson Education, Inc.

Hemoglobin A single hemoglobin molecule can carry four molecules of O2, one molecule for each iron containing heme group The hemoglobin dissociation curve shows that a small change in the partial pressure of oxygen can result in a large change in delivery of O2 CO2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O2; this is called the Bohr shift © 2011 Pearson Education, Inc. © 2011 Pearson Education, Inc.

Iron Heme Hemoglobin Figure 42.UN01
Figure 42.UN01 In-text figure, p. 924 Iron Heme Hemoglobin

O2 saturation of hemoglobin (%) O2 saturation of hemoglobin (%)
Figure 42.31 100 100 O2 unloaded to tissues at rest pH 7.4 80 80 pH 7.2 O2 unloaded to tissues during exercise Hemoglobin retains less O2 at lower pH (higher CO2 concentration) 60 60 O2 saturation of hemoglobin (%) O2 saturation of hemoglobin (%) 40 40 20 20 20 40 60 80 100 20 40 60 80 100 Figure Dissociation curves for hemoglobin at 37°C. PO (mm Hg) Tissues during exercise Tissues at rest Lungs 2 (b) pH and hemoglobin dissociation PO (mm Hg) 2 2 (a) PO and hemoglobin dissociation at pH 7.4

O2 saturation of hemoglobin (%)
Figure 42.31a 100 O2 unloaded to tissues at rest 80 O2 unloaded to tissues during exercise 60 O2 saturation of hemoglobin (%) 40 20 Figure Dissociation curves for hemoglobin at 37°C. 20 40 60 80 100 Tissues during exercise Tissues at rest Lungs PO (mm Hg) 2 (a) PO and hemoglobin dissociation at pH 7.4 2

O2 saturation of hemoglobin (%)
Figure 42.31b 100 pH 7.4 80 pH 7.2 Hemoglobin retains less O2 at lower pH (higher CO2 concentration) 60 O2 saturation of hemoglobin (%) 40 20 Figure Dissociation curves for hemoglobin at 37°C. 20 40 60 80 100 PO (mm Hg) 2 (b) pH and hemoglobin dissociation

Carbon Dioxide Transport
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–) Animation: O2 from Blood to Tissues Animation: CO2 from Tissues to Blood Animation: CO2 from Blood to Lungs Animation: O2 from Lungs to Blood © 2011 Pearson Education, Inc.

Animation: CO2 from Tissues to Blood Right-click slide / select “Play”

Animation: CO2 from Blood to Lungs Right-click slide / select “Play”

Animation: O2 from Lungs to Blood Right-click slide / select “Play”

Figure 42.32 Carbon dioxide transport in the blood.
Body tissue CO2 transport from tissues CO2 produced Interstitial fluid CO2 Plasma within capillary CO2 Capillary wall CO2 H2O Red blood cell H2CO3 Hemoglobin (Hb) picks up CO2 and H+. Hb Carbonic acid HCO3 Bicarbonate  H+ HCO3 To lungs CO2 transport to lungs HCO3 HCO3  H+ Hemoglobin releases CO2 and H+. Figure Carbon dioxide transport in the blood. H2CO3 Hb H2O CO2 CO2 CO2 CO2 Alveolar space in lung

Body tissue CO2 transport from tissues CO2 produced Interstitial fluid
Figure 42.32a Body tissue CO2 transport from tissues CO2 produced Interstitial fluid CO2 Plasma within capillary CO2 Capillary wall CO2 H2O Hemoglobin (Hb) picks up CO2 and H+. Red blood cell H2CO3 Hb Carbonic acid Figure Carbon dioxide transport in the blood. HCO3 Bicarbonate  H+ HCO3 To lungs

To lungs CO2 transport to lungs HCO3 HCO3  H+ Hemoglobin releases
Figure 42.32b To lungs CO2 transport to lungs HCO3 HCO3  H+ Hemoglobin releases CO2 and H+. Hb H2CO3 H2O CO2 CO2 Figure Carbon dioxide transport in the blood. CO2 CO2 Alveolar space in lung

Respiratory Adaptations of Diving Mammals
Diving mammals have evolutionary adaptations that allow them to perform extraordinary feats For example, Weddell seals in Antarctica 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 ratio © 2011 Pearson Education, Inc.

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 Changing their buoyancy to glide passively Decreasing blood supply to muscles Deriving ATP in muscles from fermentation once oxygen is depleted © 2011 Pearson Education, Inc.

Exhaled air Inhaled air Alveolar spaces Alveolar epithelial cells CO2
Figure 42.UN02 Exhaled air Inhaled air Alveolar spaces Alveolar epithelial cells CO2 O2 Alveolar capillaries Pulmonary arteries Pulmonary veins Systemic veins Systemic arteries Heart Figure 42.UN02 Summary figure, Concept 42.2 Systemic capillaries CO2 O2 Body tissue

100 Fetus 80 Mother O2 saturation of hemoglobin (%) 60 40 20 20 40 60
Figure 42.UN03 100 Fetus 80 Mother O2 saturation of hemoglobin (%) 60 40 20 Figure 42.UN03 Test Your Understanding, question 11 20 40 60 80 100 PO (mm Hg) 2

Figure 42.UN04 Figure 42.UN04 Appendix A: answer to Test Your Understanding, question 11

Circulation and Gas Exchange

Similar presentations

Presentation on theme: "Circulation and Gas Exchange"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Circulation and Gas Exchange

Similar presentations

Presentation on theme: "Circulation and Gas Exchange"— Presentation transcript:

Similar presentations

About project

Feedback