CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman

CAMPBELL BIOLOGY TENTH EDITION Reece  Urry  Cain  Wasserman

CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman Minorsky Jackson 42 Circulation and Gas Exchange Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick 2014 Pearson Education, Inc.

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 2014 Pearson Education, Inc. For most cells of 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 2014 Pearson Education, Inc. Figure 42.1 2014 Pearson Education, Inc. Concept 42.1: Circulatory systems link exchange surfaces with cells throughout the body Small molecules can move between cells and their surroundings by diffusion Diffusion is only efficient over small distances because the time it takes to diffuse is proportional

to the square of the distance 2014 Pearson Education, Inc. In small 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 2014 Pearson Education, Inc. Gastrovascular Cavities Some animals lack a circulatory system Some cnidarians 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 flat body that minimizes diffusion distances 2014 Pearson Education, Inc. Figure 42.2 Mouth Radial canals Circular canal (a) The moon jelly Aurelia, a cnidarian 2014 Pearson Education, Inc.

2.5 cm Mouth Gastrovascular 1 mm cavity (b) The planarian Dugesia, a flatworm Pharynx Open and Closed 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 2014 Pearson Education, Inc. In insects, other arthropods, and some molluscs, circulatory fluid called hemolymph bathes the organs directly in an open circulatory system In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid Annelids, cephalopods, and vertebrates have closed circulatory systems 2014 Pearson Education, Inc. Figure 42.3

(a) An open circulatory system (b) A closed circulatory system Heart Heart Interstitial fluid Hemolymph in sinuses Pores Small branch vessels in each organ Dorsal

vessel (main heart) Tubular heart 2014 Pearson Education, Inc. Blood Auxiliary hearts Ventral vessels Figure 42.3a

(a) An open circulatory system Heart Hemolymph in sinuses Pores Tubular heart 2014 Pearson Education, Inc. Figure 42.3b (b) A closed circulatory system Heart Interstitial fluid Blood Small

branch vessels in each organ Dorsal vessel (main heart) Auxiliary hearts Ventral vessels 2014 Pearson Education, Inc. 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 2014 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 2014 Pearson Education, Inc. 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 2014 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 2014 Pearson Education, Inc. Figure 42.4a

(a) Single circulation: fish Gill capillaries Artery Heart: Atrium (A) Ventricle (V) Vein Key 2014 Pearson Education, Inc. Oxygen-rich blood Oxygen-poor blood

Body capillaries Double Circulation Amphibians, reptiles, and mammals have double circulation Oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart 2014 Pearson Education, Inc. 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 2014 Pearson Education, Inc. Figure 42.4b (b) Double circulation: amphibian Pulmocutaneous circuit Lung and skin capillaries Atrium (A)

Atrium (A) Right Left Ventricle (V) Systemic capillaries Key 2014 Pearson Education, Inc. Systemic circuit Oxygen-rich blood Oxygen-poor blood Figure 42.4c

(c) Double circulation: mammal Pulmonary circuit Lung capillaries A A V V Right Left

Systemic capillaries Systemic circuit Key 2014 Pearson Education, Inc. Oxygen-rich blood Oxygen-poor blood Evolutionary Variation in Double Circulation Some vertebrates with double circulation are intermittent breathers For example, amphibians and many reptiles may pass long periods without gas exchange, or relying on gas exchange from another tissue, usually the skin

2014 Pearson Education, Inc. Frogs and other amphibians have a threechambered heart: two atria and one ventricle The ventricle pumps blood into a forked artery that splits the ventricles output into the pulmocutaneous circuit and the systemic circuit When underwater, blood flow to the lungs is nearly shut off 2014 Pearson Education, Inc. Turtles, snakes, and lizards have a threechambered heart: two atria and one ventricle, partially divided by an incomplete septum In alligators, caimans, and other crocodilians a septum divides the ventricles but pulmonary and systemic circuits connect where arteries exit the heart

2014 Pearson Education, Inc. 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 2014 Pearson Education, Inc. Concept 42.2: Coordinated cycles of heart contraction drive double circulation in mammals The mammalian cardiovascular system meets the

bodys continuous demand for O2 2014 Pearson Education, Inc. Mammalian Circulation Blood begins its flow with the right ventricle pumping blood to the lungs via the pulmonary arteries In the lungs, the blood loads O2 and unloads CO2 Oxygen-rich blood from the lungs enters the heart at the left atrium via the pulmonary veins It is pumped through the aorta to the body tissues by the left ventricle 2014 Pearson Education, Inc. 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 2014 Pearson Education, Inc. Figure 42.5 Superior vena cava Capillaries of head and

forelimbs 7 Pulmonary artery Capillaries of right lung Pulmonary artery Aorta 9 6 2

3 3 4 11 Pulmonary vein Right atrium Right ventricle Capillaries of left lung

1 Pulmonary vein Left atrium Left ventricle 5 10 Aorta Inferior vena cava 8

2014 Pearson Education, Inc. Capillaries of abdominal organs and hind limbs Animation: Path of Blood Flow in Mammals 2014 Pearson Education, Inc. The Mammalian Heart: A Closer Look A closer look at the mammalian heart provides a better understanding of double circulation The two atria have relatively thin walls and serve as collection chambers for blood returning to the heart The ventricles have thicker walls and contract

much more forcefully 2014 Pearson Education, Inc. Figure 42.6 Aorta Pulmonary artery Pulmonary artery Right atrium Left atrium

Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Right ventricle 2014 Pearson Education, Inc.

Left ventricle 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 2014 Pearson Education, Inc. Figure 42.7-1 1 Atrial and ventricular diastole 0.4

sec 2014 Pearson Education, Inc. Figure 42.7-2 2 Atrial systole and ventricular diastole 1 Atrial and ventricular diastole 0.1 sec 0.4 sec

2014 Pearson Education, Inc. Figure 42.7-3 2 Atrial systole and ventricular diastole 1 Atrial and ventricular diastole 0.1 sec 0.4 sec 0.3 sec

3 Ventricular systole and atrial diastole 2014 Pearson Education, Inc. 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 2014 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 2014 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 defective valve causes a heart murmur 2014 Pearson Education, Inc. Maintaining the Hearts Rhythmic Beat Some cardiac muscle cells are autorhythmic, 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) 2014 Pearson Education, Inc. Figure 42.8-1 1 Signals (yellow) from SA node spread through atria.

SA node (pacemaker) ECG 2014 Pearson Education, Inc. Figure 42.8-2 1 Signals (yellow) from SA node spread through atria. SA node (pacemaker)

ECG 2014 Pearson Education, Inc. 2 Signals are delayed at AV node. AV node Figure 42.8-3 1 Signals (yellow) from SA node spread through atria.

SA node (pacemaker) ECG 2014 Pearson Education, Inc. 2 Signals are delayed at AV node. AV node 3 Bundle branches pass signals to

heart apex. Bundle branches Heart apex Figure 42.8-4 1 Signals (yellow) from SA node spread through atria. SA node (pacemaker)

ECG 2014 Pearson Education, Inc. 2 Signals are delayed at AV node. AV node 3 Bundle branches pass signals to heart apex. Bundle

branches Heart apex 4 Signals spread throughout ventricles. Purkinje fibers 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 2014 Pearson Education, Inc. 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 2014 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 apply to the functioning of blood vessels 2014 Pearson Education, Inc. Blood Vessel Structure and Function A vessels cavity is called the central lumen The epithelial layer that lines blood vessels is called the endothelium The endothelium is smooth and minimizes resistance Capillaries are only slightly wider than a red blood cell 2014 Pearson Education, Inc.

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 2014 Pearson Education, Inc. Figure 42.9 Vein

LM Artery Red blood cells 100 m Valve Basal lamina Endothelium Smooth muscle Connective Capillary tissue Endothelium

Smooth muscle Connective tissue Artery Vein Capillary 2014 Pearson Education, Inc. 15 m Red blood cell Venule

LM Arteriole Figure 42.9a Valve Basal lamina Endothelium Smooth muscle Connective Capillary tissue Endothelium

Smooth muscle Connective tissue Artery Vein Arteriole 2014 Pearson Education, Inc. Venule Figure 42.9b

Vein LM Artery Red blood cells 100 m 2014 Pearson Education, Inc. Capillary 2014 Pearson Education, Inc. LM Red blood cell

15 m Figure 42.9c 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 2014 Pearson Education, Inc. 2014 Pearson Education, Inc.

Systolic pressure Venae cavae Veins Venules Capillaries Diastolic pressure Arterioles

120 100 80 60 40 20 0 Arteries 50 40 30 20 10 0

Aorta Velocity (cm/sec) 5,000 4,000 3,000 2,000 1,000 0 Pressure (mm Hg) Area (cm2)

Figure 42.10 2014 Pearson Education, Inc. Systolic pressure Venae cavae Veins Venules Capillaries Diastolic

pressure Arterioles 120 100 80 60 40 20 0 Arteries 50 40 30 20

10 0 Aorta Velocity (cm/sec) 5,000 4,000 3,000 2,000 1,000 0 Pressure (mm Hg)

Area (cm2) Figure 42.10a Blood Pressure Blood flows from areas of higher pressure to areas of lower pressure Blood pressure is the pressure that blood exerts in all directions, including against the walls of blood vessels The recoil of elastic arterial walls plays a role in maintaining blood pressure The resistance to blood flow in the narrow diameters of tiny capillaries and arterioles dissipates much of the pressure 2014 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 2014 Pearson Education, Inc. Regulation of Blood Pressure Homeostatic mechanisms regulate arterial blood pressure by altering the diameter 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 2014 Pearson Education, Inc. Nitric oxide is a major inducer of vasodilation The peptide endothelin is a strong inducer of vasoconstriction Vasoconstriction and vasodilation are often coupled to changes in cardiac output that affect blood pressure 2014 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 human at rest is about 120 mm Hg at systole and 70 mm Hg at diastole Gravity has a significant effect on blood pressure 2014 Pearson Education, Inc. Figure 42.11 Pressure in cuff greater than 120 mm Hg Cuff inflated with air

1 Artery closed 2014 Pearson Education, Inc. Pressure in cuff drops below 120 mm Hg 120 Pressure in cuff below 70 mm Hg

120 70 2 Sounds audible in stethoscope 3 Sounds stop Fainting is caused by inadequate blood flow to the head

Animals with long necks require a very high systolic pressure to pump blood a great 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 2014 Pearson Education, Inc. Figure 42.12 Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle

Valve (closed) 2014 Pearson Education, Inc. Capillary Function Blood flows through only 510% of the bodys capillaries at any given time Capillaries in major organs are usually filled to capacity Blood supply varies in many other sites 2014 Pearson Education, Inc. Two mechanisms regulate distribution of blood in capillary beds Constriction or dilation of arterioles that supply

capillary beds Precapillary sphincters that control flow of blood between arterioles and venules Blood flow is regulated by nerve impulses, hormones, and other chemicals 2014 Pearson Education, Inc. Figure 42.13 Precapillary sphincters Arteriole Thoroughfare channel

Capillaries Venule (a) Sphincters relaxed Arteriole (b) Sphincters contracted 2014 Pearson Education, Inc. Venule 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 2014 Pearson Education, Inc. Figure 42.14 INTERSTITIAL FLUID Net fluid movement out Body cell Blood

pressure Osmotic pressure Arterial end of capillary 2014 Pearson Education, Inc. Direction of blood flow Venous end of capillary Fluid Return by the Lymphatic System The lymphatic system returns fluid that leaks out from the capillary beds

Fluid lost by capillaries is called lymph The lymphatic system drains into veins in the neck Valves in lymph vessels prevent the backflow of fluid 2014 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 bodys defense When the body is fighting an infection, lymph nodes become swollen and tender 2014 Pearson Education, Inc. Figure 42.15

Lymph nodes 2014 Pearson Education, Inc. Concept 42.4: Blood components function in exchange, transport, and defense With open circulation, the fluid is continuous with the fluid surrounding all body cells The closed circulatory systems of vertebrates contain a more highly specialized fluid called blood 2014 Pearson Education, Inc. Blood Composition and Function Blood in vertebrates is a connective tissue consisting of several kinds of cells suspended

in a liquid matrix called plasma The cellular elements occupy about 45% of the volume of blood 2014 Pearson Education, Inc. Figure 42.16 Plasma 55% Constituent Major functions Water Solvent

Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance, pH buffering, and regulation of membrane permeability Plasma proteins Albumin

Cellular elements 45% Separated blood elements Osmotic balance, pH buffering Defense Apolipoproteins Lipid transport Fibrinogen

Clotting 5,00010,000 Leukocytes (white blood cells) Functions Defense and immunity Lymphocytes Basophils Immunoglobulins (antibodies)

Number per L (mm3) of blood Cell type Eosinophils Neutrophils Platelets Monocytes 250,000400,000 Blood clotting Substances transported by blood

Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones 2014 Pearson Education, Inc. Erythrocytes (red blood cells) 5,000,0006,000,000 Transport of O2 and some CO2 Figure 42.16a Plasma 55%

Constituent Major functions Water Solvent Ions (blood electrolytes) Sodium, Potassium Calcium, Magnesium Chloride, Bicarbonate Osmotic balance, pH buffering, and regulation

of membrane permeability Plasma proteins Albumin Immunoglobulins (antibodies) Apolipoproteins Fibrinogen Osmotic balance, pH buffering Defense Lipid transport Clotting Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins)

Waste products of metabolism Respiratory gases (O2 and CO2) Hormones 2014 Pearson Education, Inc. Figure 42.16b Cellular elements 45% Number per L (mm3) of blood Cell type Leukocytes (white blood cells) 5,00010,000

Functions Defense and immunity Lymphocytes Basophils Eosinophils Neutrophils Platelets Erythrocytes (red blood cells) 2014 Pearson Education, Inc.

Monocytes 250,000400,000 Blood clotting 5,000,0006,000,000 Transport of O2 and some CO2 Plasma Plasma contains inorganic salts as dissolved ions, sometimes called electrolytes Plasma proteins influence blood pH and help maintain osmotic balance between blood and interstitial fluid Particular plasma proteins function in lipid

transport, immunity, and blood clotting Plasma is similar in composition to interstitial fluid, but plasma has a much higher protein concentration 2014 Pearson Education, Inc. Cellular Elements Suspended in blood plasma are two types of cells Red blood cells (erythrocytes) transport O2 White blood cells (leukocytes) function in defense Platelets are fragments of cells that are involved in clotting 2014 Pearson Education, Inc. Erythrocytes

Red blood cells, or erythrocytes, are 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 2014 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 2014 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 either by phagocytizing bacteria and debris or by mounting immune responses against foreign substances They are found both in and outside of the circulatory system 2014 Pearson Education, Inc. Platelets Platelets are fragments of cells and function in blood clotting 2014 Pearson Education, Inc.

Stem Cells and the Replacement of Cellular Elements 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 Physicians can use recombinant EPO to treat people with conditions such as anemia 2014 Pearson Education, Inc. Figure 42.17 Stem cells

(in bone marrow) Myeloid stem cells Lymphoid stem cells B cells T cells Erythrocytes Lymphocytes Monocytes 2014 Pearson Education, Inc.

Neutrophils Platelets Basophils Eosinophils 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 2014 Pearson Education, Inc.

Figure 42.18 1 2 3 Collagen fibers Platelet plug Platelet Clotting factors from:

Platelets Damaged cells Plasma (factors include calcium, vitamin K) Enzymatic cascade Prothrombin Thrombin Fibrinogen 2014 Pearson Education, Inc. Fibrin Fibrin clot Fibrin clot formation

Red blood cells caught in threads of fibrin 5 m Figure 42.18a 1 2 3 Platelet plug

Collagen fibers Platelet Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Enzymatic cascade Prothrombin Thrombin Fibrinogen 2014 Pearson Education, Inc. Fibrin

Fibrin clot Fibrin clot formation Figure 42.18b Red blood cells caught in threads of fibrin 2014 Pearson Education, Inc. 5 m Cardiovascular Disease Cardiovascular diseases are disorders of the heart and the blood vessels These diseases range in seriousness from minor

disturbances of vein or heart function to lifethreatening disruptions of blood flow to the heart or brain 2014 Pearson Education, Inc. Atherosclerosis, Heart Attacks, and Stroke One type of cardiovascular disease, atherosclerosis, is caused by the buildup of fatty deposits (plaque) within arteries Cholesterol is a key player in the development of atherosclerosis 2014 Pearson Education, Inc. Low-density lipoprotein (LDL) delivers cholesterol to cells for membrane production High-density lipoprotein (HDL) scavenges

excess 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 2014 Pearson Education, Inc. Figure 42.19 Endothelium Lumen Thrombus Plaque 2014 Pearson Education, Inc.

A heart attack, or myocardial infarction, is the damage or death of cardiac muscle tissue resulting from blockage of one or more coronary arteries 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 chest pain caused by partial blockage of the coronary arteries 2014 Pearson Education, Inc. Figure 42.20 1 A stent and a balloon are inserted into an

obstructed artery. Artery Plaque Stent around balloon 2 Inflating the balloon expands the stent, widening the artery. 3 The balloon is removed, leaving the stent in place.

2014 Pearson Education, Inc. Increased blood flow Risk Factors and Treatment of Cardiovascular Disease A high LDL/HDL ratio increases the risk of cardiovascular disease The proportion of LDL relative to HDL can be decreased by exercise and by avoiding smoking and foods with trans fats Drugs called statins reduce LDL levels and risk of heart attacks 2014 Pearson Education, Inc.

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, also contributes to heart attack and stroke, as well as other health problems Hypertension can be controlled by dietary changes, exercise, and/or medication 2014 Pearson Education, Inc. Partial Pressure Gradients in Gas Exchange Partial pressure is the pressure exerted by a particular gas in a mixture of gases Partial pressures also apply to gases dissolved in liquids such as water

Gases undergo net diffusion from a region of higher partial pressure to a region of lower partial pressure 2014 Pearson Education, Inc. Table 42.1 2014 Pearson Education, Inc. Respiratory Media Animals can use air or water as the O2 source, 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

2014 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 skin, gills, tracheae, and lungs 2014 Pearson Education, Inc. Gills in Aquatic Animals Gills are outfoldings of the body that create a large surface area for gas exchange

Ventilation moves the respiratory medium over the respiratory surface Aquatic animals move through water or move water over their gills for ventilation 2014 Pearson Education, Inc. 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 animals metabolic rate 2014 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 filtered, warmed, humidified, and sampled for odors The pharynx directs air to the lungs and food to the stomach Swallowing moves the larynx upward and tips the epiglottis over the glottis in the pharynx to prevent food from entering the trachea 2014 Pearson Education, Inc. 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 2014 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 2014 Pearson Education, Inc. Figure 42.24

Branch of pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch of pulmonary artery (oxygen-poor blood) Nasal cavity Pharynx Larynx

Left lung (Esophagus) Alveoli 50 m Trachea Right lung Capillaries Bronchus Bronchiole Diaphragm (Heart)

2014 Pearson Education, Inc. Dense capillary bed enveloping alveoli (SEM) Figure 42.24a Nasal cavity Pharynx Larynx Left lung (Esophagus) Trachea

Right lung Bronchus Bronchiole Diaphragm (Heart) 2014 Pearson Education, Inc. Figure 42.24b Branch of pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch of

pulmonary artery (oxygen-poor blood) Alveoli Capillaries 2014 Pearson Education, Inc. Figure 42.24c 50 m Dense capillary bed enveloping alveoli (SEM)

2014 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 2014 Pearson Education, Inc. Concept 42.6: Breathing ventilates the lungs The process that ventilates the lungs is breathing, the alternate inhalation and exhalation of air 2014 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 2014 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 Passage of air through the entire system of lungs and air sacs requires two cycles of inhalation and exhalation Ventilation in birds is highly efficient

2014 Pearson Education, Inc. The tidal volume is the volume of air inhaled with each breath The maximum tidal volume is the vital capacity After exhalation, a residual volume of air remains in the lungs 2014 Pearson Education, Inc. Figure 42.27 Rib cage gets smaller as rib muscles relax.

Rib cage expands as rib muscles contract. Lung Diaphragm 1 INHALATION: Diaphragm contracts (moves down). 2014 Pearson Education, Inc. 2 EXHALATION: Diaphragm relaxes (moves up).

Control of Breathing in Humans In humans, breathing is usually regulated by involuntary mechanisms The breathing control centers are found in the medulla oblongata of the brain The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid 2014 Pearson Education, Inc. Figure 42.28 Blood CO2 level falls and pH rises. NORMAL BLOOD pH

(about 7.4) Medulla detects decrease in pH of cerebrospinal fluid. Cerebrospinal fluid Signals from medulla to rib muscles and diaphragm increase rate and depth of ventilation. 2014 Pearson Education, Inc.

Carotid arteries Aorta Medulla oblongata Blood pH falls due to rising levels of CO2 in tissues (such as when exercising). Medulla receives signals from major blood vessels. Sensors in major

blood vessels detect decrease in blood pH. Sensors in the aorta and carotid arteries monitor O2 and CO2 concentrations in the blood These signal the breathing control centers, which respond as needed Additional modulation of breathing takes place in the pons, next to the medulla 2014 Pearson Education, Inc. 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 2014 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 2014 Pearson Education, Inc. Figure 42.29

160 120 27 6 Exhaled air Inhaled air 1 PO 2 PCO 2 PO 2 PCO 2 Alveolar epithelial cells

40 CO2 O2 Alveolar spaces 2 Alveolar capillaries Blood entering alveolar capillaries 45

PO 2 PCO 2 0.2 104 40 PO 2 PCO 2 5 Pulmonary veins and systemic 3 arteries Pulmonary

arteries and systemic veins 104 40 PO 2 PCO 2 <40 >45 PO 2 PCO 2 2014 Pearson Education, Inc.

4 Body tissue CO2 O2 Systemic capillaries 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 2014 Pearson Education, Inc. Figure 42.UN02 Iron Heme Hemoglobin 2014 Pearson Education, Inc. A single hemoglobin molecule can carry four molecules of O2, one molecule for each ironcontaining 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 2014 Pearson Education, Inc. CO2 produced during cellular respiration lowers blood pH and decreases the affinity of hemoglobin for O2; this is called the Bohr shift Hemoglobin plays a minor role in transport of CO2 and assists in buffering the blood 2014 Pearson Education, Inc. Carbon Dioxide Transport Some CO2 from respiring cells diffuses into the blood and is transported in blood plasma, bound to hemoglobin The remainder diffuses into erythrocytes and

reacts with water to form H2CO3, which dissociates into H+ and bicarbonate ions (HCO3) In the lungs the relative partial pressures of CO 2 favor the net diffusion of CO2 out of the blood 2014 Pearson Education, Inc. 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

2014 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 2014 Pearson Education, Inc. Figure 42.UN01a 2014 Pearson Education, Inc.

Figure 42.UN01b 2014 Pearson Education, Inc. Figure 42.UN04 Inhaled air Exhaled air Alveolar epithelial cells Alveolar spaces CO2

O2 Alveolar capillaries Pulmonary arteries Pulmonary veins Systemic veins Systemic arteries Heart

CO2 Body tissue 2014 Pearson Education, Inc. O2 Systemic capillaries O2 saturation of hemoglobin (%) Figure 42.UN05 100

80 60 Mother 40 20 0 2014 Pearson Education, Inc. Fetus 0 20 40 60 80 100 PO 2 (mm Hg)

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