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Circulation and Gas Exchange
Chapter 42 Circulation and Gas Exchange
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Objective: You will be able to explain how various organisms use circulatory systems to exchange materials. Do Now: Read p. 872 – 873 “Open and closed circulatory…” Differentiate between closed and open circulatory systems
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Blood Connects the intercellular fluid to the organs that exchange nutrients, gasses and wastes
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Figure 42.3 Open and closed circulatory systems
Heart Hemolymph in sinuses surrounding ograns Interstitial fluid Small branch vessels in each organ Anterior vessel Lateral vessels Ostia Tubular heart Dorsal vessel (main heart) Ventral vessels Auxiliary hearts (a) An open circulatory system (b) A closed circulatory system
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Figure 42.4 Vertebrate Circulatory Systems
FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS Systemic capillaries Lung capillaries Lung and skin capillaries Gill capillaries Right Left Systemic circuit Pulmocutaneous circuit Pulmonary circuit Systemic circulation Vein Atrium (A) Heart: ventricle (V) Artery Gill circulation A V Systemic aorta Right systemic aorta
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Figure 42.5 The mammalian cardiovascular system: an overview
Right atrium Right ventricle Posterior vena cava Capillaries of abdominal organs and hind limbs Aorta Left ventricle Left atrium Pulmonary vein artery Capillaries of left lung head and forelimbs Anterior of right lung 1 10 11 5 4 6 2 9 3 7 8
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Figure 42.12 Measurement of blood pressure (layer 1)
Artery
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Figure 42.12 Measurement of blood pressure (layer 2)
Artery Rubber cuff inflated with air Artery closed 120 Pressure in cuff above120
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Figure 42.12 Measurement of blood pressure (layer 3)
Artery Rubber cuff inflated with air Artery closed 120 Pressure in cuff above120 Pressure in cuff below 120 Sounds audible in stethoscope
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Figure 42.12 Measurement of blood pressure (layer 4)
Artery Rubber cuff inflated with air Artery closed 120 70 Pressure in cuff above120 Pressure in cuff below 120 Pressure in cuff below 70 Sounds audible in stethoscope Sounds stop Blood pressure Reading: 120/170
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Objective: You will be able to explain how capillaries exchange materials with the intercellular fluid. Do Now: Read p. 877 – 888 “Structural differences…” Explain the structural differences between the three transport vessels
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Figure 42.6 The mammalian heart: a closer look
Aorta Pulmonary artery Left atrium Pulmonary veins Semilunar valve Atrioventricular valve Left ventricle Right ventricle Anterior vena cava Posterior vena cava Right atrium
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Figure 42.7 The cardiac cycle
Semilunar valves closed AV valve open AV valve closed Semilunar valves open Atrial and ventricular diastole 1 Atrial systole; ventricular diastole 2 Ventricular systole; atrial diastole 3 0.1 sec 0.3 sec 0.4 sec
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Figure 42.8 The control of heart rhythm
SA node (pacemaker) AV node Bundle branches Heart apex Purkinje fibers 1 2 Signals are delayed at AV node. Pacemaker generates wave of signals to contract. 3 Signals pass to heart apex. 4 Signals spread throughout ventricles. ECG
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Figure 42.9 The structure of blood vessels
Artery Vein 100 µm Arteriole Venule Connective tissue Smooth muscle Endothelium Valve Basement membrane Capillary
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Figure 42.13 Blood flow in capillary beds
Precapillary sphincters Thoroughfare channel Arteriole Capillaries Venule (a) Sphincters relaxed (b) Sphincters contracted (c) Capillaries and larger vessels (SEM) 20 m
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Arterial end of capillary
Figure 42.14 Fluid exchange between capillaries and the interstitial fluid Tissue cell INTERSTITIAL FLUID Net fluid movement out Net fluid movement in Capillary Capillary Red blood cell 15 m At the venule end of a capillary, blood pressure is less than osmotic pressure, and fluid flows from the interstitial fluid into the capillary. At the arterial end of a capillary, blood pressure is greater than osmotic pressure, and fluid flows out of the capillary into the interstitial fluid. Direction of blood flow Blood pressure Osmotic pressure Inward flow Pressure Outward flow Arterial end of capillary Venule end
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Figure 42.10 Blood flow in veins
Direction of blood flow in vein (toward heart) Valve (open) Skeletal muscle Valve (closed)
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Activity Many physiological changes occur during exercise.
Design a controlled experiment to test the hypothesis that an exercise session causes short-term increases in heart rate and breathing rate in humans. Explain how at least three organ systems are affected by this increased physical activity and discuss interactions among these systems.
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Give the functions of plasma
Objective:You will be able to discuss the structure and function of blood. Do Now: Read “Plasma” on p. 882 – 883 Give the functions of plasma
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Objective: You will be able to discuss the structure and function of blood.
Do Now: Read “Plasma” on p. 882 – 883 Give the functions of plasma
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Figure 42.15 The composition of mammalian blood
Plasma 55% Constituent Major functions Water Solvent for carrying other substances Sodium Potassium Calcium Magnesium Chloride Bicarbonate Osmotic balance pH buffering, and regulation of membrane permeability Albumin Fibringen Immunoglobulins (antibodies) Plasma proteins Icons (blood electrolytes Osmotic balance, pH buffering Clotting Defense Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Cellular elements 45% Cell type Number per L (mm3) of blood Separated blood elements Functions Erythrocytes (red blood cells) 5–6 million Transport oxygen and help transport carbon dioxide Leukocytes (white blood cells) 5,000–10,000 Defense and immunity Eosinophil Basophil Platelets Neutrophil Monocyte Lymphocyte 250,000 400,000 Blood clotting
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Figure 42.16 Differentiation of blood cells
B cells T cells Lymphoid stem cells Pluripotent stem cells (in bone marrow) Myeloid stem cells Erythrocytes Platelets Monocytes Neutrophils Eosinophils Basophils Lymphocytes
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Figure 42.17 Blood clotting Collagen fibers Platelet plug Fibrin clot
3 This seal is reinforced by a clot of fibrin when vessel damage is severe. Fibrin is formed via a multistep process: Clotting factors released from the clumped platelets or damaged cells mix with clotting factors in the plasma, forming an activation cascade that converts a plasma protein called prothrombin to its active form, thrombin. Thrombin itself is an enzyme that catalyzes the final step of the clotting process, the conversion of fibrinogen to fibrin. The threads of fibrin become interwoven into a patch (see colorized SEM). 1 The clotting process begins when the endothelium of a vessel is damaged, exposing connective tissue in the vessel wall to blood. Platelets adhere to collagen fibers in the connective tissue and release a substance that makes nearby platelets sticky. 2 The platelets form a plug that provides emergency protection against blood loss. Collagen fibers Platelet plug Fibrin clot Red blood cell Platelet releases chemicals that make nearby platelets sticky Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Prothrombin Thrombin Fibrinogen Fibrin 5 µm
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Figure 42.18 Atherosclerosis
(a) Normal artery (b) Partly clogged artery 50 µm 250 µm Smooth muscle Connective tissue Endothelium Plaque
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Figure 42.21 The structure and function of fish gills
Oxygen-poor blood Gill arch Oxygen-rich blood Lamella Blood vessel Gill arch 15% 40% 70% 5% 30% Water flow 60% 100% Operculum 90% Water flow over lamellae showing % O2 Gill filaments Blood flow through capillaries in lamellae showing % O2 Countercurrent exchange
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Figure 42.22 Tracheal systems
Spiracle Tracheae Air sacs Air sac Body cell Air Trachea Tracheole Tracheoles Mitochondria Myofibrils Body wall 2.5 µm (a) The respiratory system of an insect consists of branched internal tubes that deliver air directly to body cells. Rings of chitin reinforce the largest tubes, called tracheae, keeping them from collapsing. Enlarged portions of tracheae form air sacs near organs that require a large supply of oxygen. Air enters the tracheae through openings called spiracles on the insect’s body surface and passes into smaller tubes called tracheoles. The tracheoles are closed and contain fluid (blue-gray). When the animal is active and is using more O2, most of the fluid is withdrawn into the body. This increases the surface area of air in contact with cells. (b) This micrograph shows cross sections of tracheoles in a tiny piece of insect flight muscle (TEM). Each of the numerous mitochondria in the muscle cells lies within about 5 µm of a tracheole.
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Figure 42.23 The mammalian respiratory system
Branch from the pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch from the pulmonary artery (oxygen-poor blood) Alveoli Colorized SEM SEM 50 µm Heart Left lung Nasal cavity Pharynx Larynx Diaphragm Bronchiole Bronchus Right lung Trachea Esophagus
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Figure 42.24 Negative pressure breathing
Rib cage expands as rib muscles contract Rib cage gets smaller as rib muscles relax Air inhaled Air exhaled Lung Diaphragm INHALATION Diaphragm contracts (moves down) EXHALATION Diaphragm relaxes (moves up)
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Figure 42.26 Automatic control of breathing
Cerebrospinal fluid The control center in the medulla sets the basic rhythm, and a control center in the pons moderates it, smoothing out the transitions between inhalations and exhalations. 1 The medulla’s control center also helps regulate blood CO2 level. Sensors in the medulla detect changes in the pH (reflecting CO2 concentration) of the blood and cerebrospinal fluid bathing the surface of the brain. 4 Nerve impulses relay changes in CO2 and O2 concentrations. Other sensors in the walls of the aorta and carotid arteries in the neck detect changes in blood pH and send nerve impulses to the medulla. In response, the medulla’s breathing control center alters the rate and depth of breathing, increasing both to dispose of excess CO2 or decreasing both if CO2 levels are depressed. 5 Pons Nerve impulses trigger muscle contraction. Nerves from a breathing control center in the medulla oblongata of the brain send impulses to the diaphragm and rib muscles, stimulating them to contract and causing inhalation. 2 Breathing control centers Medulla oblongata Carotid arteries Aorta In a person at rest, these nerve impulses result in about 10 to 14 inhalations per minute. Between inhalations, the muscles relax and the person exhales. 3 The sensors in the aorta and carotid arteries also detect changes in O2 levels in the blood and signal the medulla to increase the breathing rate when levels become very low. 6 Diaphragm Rib muscles
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Figure 42.27 Loading and unloading of respiratory gases
Inhaled air Exhaled air 160 0.2 O2 CO2 Alveolar epithelial cells Pulmonary arteries Blood entering alveolar capillaries Blood leaving tissue capillaries Blood entering tissue capillaries Blood leaving alveolar capillaries Tissue capillaries Heart Alveolar capillaries of lung <40 >45 Tissue cells Pulmonary veins Systemic arteries Systemic veins Alveolar spaces 1 2 4 3
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Figure 42.28 Hemoglobin loading and unloading O2
Heme group Iron atom O2 loaded in lungs O2 unloaded In tissues Polypeptide chain O2
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Unnumbered figure page 897
100 80 60 40 20 PO2 (mm Hg) Fetus Mother O2 saturation of hemoglobin (%)
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