Capillary Func4on exchange of substances between blood and inters44al fluid across thin endothelial capillary walls difference between blood pressure and osmo4c pressure Drives fluids out of capillaries at the arteriole end and into capillaries at the venule end Body tissue Capillary Pressure Direction of blood flow INTERSTITIAL FLUID Net fluid movement out Outward flow Blood pressure Arterial end of capillary Osmotic pressure Net fluid movement in Inward flow Venous end Lympha'c system Fluid Return by the Lympha4c System Returns fluid that leaks out of capillary beds Inters44al fluid Also aids in body defense Lymph Reenters circula4on directly at venous end of the capillary bed and indirectly through the lympha4c system lympha4c system drains into veins in neck Lymph nodes Fluid Return by the Lympha4c System Organs that filter lymph and play an important role in the body s defense Filled with lymphocytes Edema is swelling caused by disrup4ons in the flow of lymph 1
Blood Composi4on and Func4on Blood Consists of several kinds of cells suspended in a liquid matrix called plasma cellular elements occupy about 45% of the volume of blood Plasma 55% Constituent Major functions Cellular elements 45% Water Solvent for carrying other substances Ions (blood electrolytes) Sodium Osmotic balance, Separated Potassium ph buffering, and blood Calcium regulation of elements Magnesium membrane Chloride permeability Bicarbonate Plasma proteins Albumin Osmotic balance ph buffering Fibrinogen Clotting Immunoglobulins Defense (antibodies) Substances transported by blood Nutrients (such as glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O 2 and CO 2) Hormones Cell type Erythrocytes (red blood cells) Number per µl (mm 3 ) of blood 5 6 million Functions Transport oxygen and help transport carbon dioxide Leukocytes 5,000 10,000 Defense and (white blood cells) immunity Basophil Platelets Neutrophil Eosinophil 250,000 400,000 Lymphocyte Monocyte Blood clotting Plasma Blood plasma about 90% water Solutes Inorganic salts in the form of dissolved ions electrolytes Plasma proteins Which influence blood ph Osmo4c pressure Viscosity Various plasma proteins func4on in lipid transport, immunity, and blood closng Cellular Elements Suspended in blood plasma are two types of cells: Erythrocytes (Red blood cells) Transport oxygen Leukocytes (White blood cells) Immunity Platelets Cellular fragments involved in closng 2
Erythrocytes Erythrocytes By far the most numerous blood cells Transport oxygen throughout the body Contain hemoglobin Iron- containing protein that transports oxygen Mammalian anucleate Leukocytes Leukocytes Five major types: Monocytes, neutrophils, basophils, eosinophils, and lymphocytes Func4on in defense Phagocy4ze bacteria and debris or produce an4bodies Found both in and outside of the circulatory system Platelets Platelets (thrombocyte) Fragments of cells (megakaryocyte) Func4on in blood closng 3
Blood CloSng Occurs when endothelium of blood vessel is damaged Cascade of complex reac4ons converts fibrinogen to fibrin Forms a clot Collagen fibers Platelet plug Platelet releases chemicals that make nearby platelets sticky Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Fibrin clot Red blood cell Thrombus A blood clot formed within a blood vessel Prothrombin Thrombin Fibrinogen Fibrin 5 µm Can block blood flow Respiratory System Gas exchange Supplies oxygen for cellular respira4on and disposes of carbon dioxide Par4al Pressure Gradients in Gas Exchange Gases Diffuse down pressure (concentra4on) gradients as a result of differences in par4al pressure In the lungs External Respira4on Other organs Internal Respira4on Par'al pressure Pressure exerted by a par4cular gas in a mixture of gases 4
Par4al Pressure Gradients in Gas Exchange gas diffuses from a region of higher par4al pressure to a region of lower par4al pressure In the lungs and 4ssues O 2 and CO 2 diffuse from where their par4al pressures are higher to where they are lower Animals Respiratory Media Can use air or water as a source of O 2 or respiratory medium In a given volume there is less O 2 available in water than in air Colder water can hold more O 2 than warmer Obtaining O 2 from water requires greater efficiency than air breathing Respiratory surfaces vary by animal Can include outer surface skin, gills, tracheae, and lungs Gills in Aqua4c Animals Gills Out- foldings of the body create a large surface area for gas exchange Coelom Parapodium (functions as gill) (a) Marine worm Gills (b) Crayfish Gills (c) Sea star Tube foot 5
Ven'la'on Moves the respiratory medium over the respiratory surface Aqua4c animals Move through water or move water over their gills Fish gills for ven4la4on Gills in Aqua4c Animals Anatomy of gills Gill arch Water flow Operculum Use a countercurrent exchange system blood flows in the opposite direc4on to water passing over the gills Blood is always less saturated with O 2 than the water it meets Gill arch Gill filaments Gill filament organization Blood vessels Oxygen-poor blood Oxygen-rich blood Net diffusion of O 2 from water to blood Water flow between lamellae Fluid flow through gill filament Lamella Blood flow through capillaries in lamella Countercurrent exchange P O2 (mm Hg) in water 150 120 90 60 30 140110 80 50 20 P O2 (mm Hg) in blood Tracheal system Tracheal Systems in Insects Consists of 4ny branching tubes that penetrate the body Air sacs Tracheal tubes supply O 2 Tracheae directly to body cells External opening Tracheoles Mitochondria Muscle fiber Respiratory and circulatory systems are separate Body cell Tracheole Air sac Larger insects Trachea must ven4late their tracheal Air Body wall 2.5 µm system to meet O 2 demands Lungs Lungs An in- folding of the body surface 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 6
Mammalian Respiratory Systems: A Closer Look Air inhaled through the nostrils passes through Pharynx Larynx Trachea Bronchi Pharynx Larynx (Esophagus) Trachea Right lung Branch of pulmonary vein (oxygen-rich blood) Nasal cavity Left lung Terminal bronchiole Branch of pulmonary artery (oxygen-poor blood) Alveoli Bronchioles Bronchus Bronchiole Alveoli Diaphragm where gas exchange occurs Heart SEM Colorized 50 µm SEM 50 µm Exhaled air passes over the vocal cords to create sounds Secre4ons called surfactants coat the surface of the alveoli How an Amphibian Breathes Posi've pressure breathing Amphibian lung ven4la4on Air drawn into oral cavity Nostrils close Floor of oral cavity raised Forces air down the trachea Nega've pressure breathing How a Mammal Breathes Diaphragm contracts, pulling down Tidal volume Lung volume increases Creates nega4ve pressure Volume of air inhaled with each relaxed breath Rib cage expands as rib muscles contract Rib cage gets Air smaller as Air inhaled rib muscles exhaled relax Lung Diaphragm INHALATION EXHALATION Diaphragm contracts Diaphragm relaxes (moves down) (moves up) Vital Capacity Maximum inhala4on volume Aaer exhala4on, a residual volume of air remains in the lungs 7
How a Bird Breathes Birds Have eight or nine air sacs Func4on as bellows that keep air flowing through the lungs Air passes through the lungs in one direc4on only Every exhala4on completely renews the air in the lungs Anterior air sacs Air Air Posterior air sacs Lungs Trachea Lungs INHALATION Air sacs fill Air tubes (parabronchi) in lung EXHALATION Air sacs empty; lungs fill 1 mm Control of Breathing in Humans Breathing control centers Are in two regions of the brain Medulla oblongata and the pons Medulla Regulates the rhythm and depth of breathing In response to ph changes in the cerebrospinal fluid Adjusts breathing rhythm and depth to match metabolic demands Pons Regulates the rate Control of Breathing in Humans Sensors in the aorta and caro4d arteries Monitor O 2 and CO 2 concentra4ons in the blood These sensors exert secondary control over breathing Breathing control centers Cerebrospinal fluid Pons Medulla oblongata Carotid arteries Aorta Diaphragm Rib muscles 8
Coordina4on of Circula4on and Gas Exchange Blood arriving in the lungs Has a low par4al pressure of O 2 and a high par4al pressure of CO 2 In the alveoli Rela4ve to air in the alveoli O 2 diffuses into the blood and CO 2 diffuses into the air In 4ssue capillaries O 2 diffuses into inters44al fluids and CO 2 into the blood Alveolus P O2 = 100 mm Hg P O2 = 40 P O2 = 100 P O2 = 40 (a) Oxygen Circulatory system P O2 40 mm Hg P O2 = 100 Body tissue P CO2 = 46 P CO2 = 40 mm Hg Circulatory system Alveolus P CO2 = 40 P CO2 = 46 P CO2 = 40 (b) Carbon dioxide P CO2 46 mm Hg Body tissue 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 contained within erythrocytes A single hemoglobin molecule Can carry four molecules of O 2 The hemoglobin dissocia4on curve Hemoglobin β Chains α Chains Hemoglobin Shows that a small change in the par4al pressure of oxygen Iron Heme O 2 saturation of hemoglobin (%) 100 80 60 40 20 0 O 2 unloaded to tissues at rest O 2 unloaded to tissues during exercise 20 60 0 40 80 100 Tissues during exercise Tissues at rest P O2 (mm Hg) Lungs (a) P O2 and hemoglobin dissociation at ph 7.4 can result in a large change in delivery of O 2 CO 2 produced during cellular respira4on Lowers blood ph and decreases the affinity of hemoglobin for O 2 O 2 saturation of hemoglobin (%) 100 80 60 40 20 ph 7.4 ph 7.2 Hemoglobin retains less O 2 at lower ph (higher CO 2 concentration) Called the Bohr shif 0 20 60 0 40 80 100 P O2 (mm Hg) (b) ph and hemoglobin dissociation 9
CO 2 Carbon Dioxide Transport Hemoglobin Also helps transport CO 2 and assists in buffering CO 2 from respiring cells Diffuses into the blood and is transported either In blood plasma 7% Bound to hemoglobin Carboxyhemoglobin - 23% Bicarbonate ions (HCO 3 ) 70% Body tissue CO 2 transport CO 2 produced from tissues Interstitial CO fluid 2 Plasma CO 2 Capillary within capillary wall CO 2 H 2 O Red Hemoglobin H blood 2 CO 3 Hb picks up cell Carbonic acid CO 2 and H + HCO 3 + H + Bicarbonate HCO 3 To lungs CO 2 transport HCO 3 to lungs HCO H + 3 + Hemoglobin H Hb releases 2 CO 3 CO 2 and H + H 2 O CO 2 CO 2 CO 2 Alveolar space in lung You should now be able to: 1. Compare and contrast open and closed circulatory systems 2. Compare and contrast the circulatory systems of fish, amphibians, non- bird rep4les, and mammals or birds 3. Dis4nguish between pulmonary and systemic circuits and explain the func4on of each 4. Trace the path of a red blood cell through the human heart, pulmonary circuit, and systemic circuit 5. Define cardiac cycle and explain the role of the sinoatrial node 6. Relate the structures of capillaries, arteries, and veins to their func4on 7. Define blood pressure and cardiac output and describe two factors that influence each 8. Explain how osmo4c pressure and hydrosta4c pressure regulate the exchange of fluid and solutes across the capillary walls You should now be able to: 9. Describe the role played by the lympha4c system in rela4on to the circulatory system 10. Describe the func4on of erythrocytes, leukocytes, platelets, fibrin 11. Discuss the advantages and disadvantages of water and of air as respiratory media 12. For humans, describe the exchange of gases in the lungs and in 4ssues 13. Draw and explain the hemoglobin- oxygen dissocia4on curve 10