Erythrocytes Erythrocytes By far the most numerous blood cells Transport oxygen throughout the body Contain hemoglobin Iron containing protein that transports oxygen Leukocytes Leukocytes Five major types: Monocytes, neutrophils, basophils, eosinophils, and lymphocytes FuncBon in defense PhagocyBze bacteria and debris or produce anbbodies Found both in and outside of the circulatory system Platelets Platelets (thrombocyte) Fragments of cells (megakaryocyte) FuncBon in blood clohng 1
Blood Clo7ng Occurs when the endothelium of a blood vessel is damaged Cascade of complex reacbons converts fibrinogen to fibrin Thrombus Forms a clot A blood clot formed within a blood vessel Can block blood flow Fig. 42-18-1 Collagen fibers Platelet releases chemicals that make nearby platelets sticky Platelet plug Fig. 42-18-2 Collagen fibers Platelet releases chemicals that make nearby platelets sticky Platelet plug Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) 2
Fig. 42-18-3 Collagen fibers Platelet releases chemicals that make nearby platelets sticky Platelet plug Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Prothrombin Thrombin Fig. 42-18-4 Collagen fibers Platelet releases chemicals that make nearby platelets sticky Platelet plug Fibrin clot Red blood cell Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Prothrombin Thrombin Fibrinogen Fibrin 5 µm Stem Cells and Replacement of Cellular Elements Blood cells have limited life span RBC s: 100 120 days; WBC s 15 30 days Replaced constantly throughout a person s life Removed by phagocybc cells in liver and spleen Produce 2.4 million per second Erythrocytes, leukocytes, and platelets All develop from a common source of stem cells In the red marrow of bones The hormone erythropoie?n (EPO) sbmulates erythrocyte producbon when oxygen delivery is low 3
Fig. 42-19 Stem cells (in bone marrow) Lymphoid stem cells Myeloid stem cells Lymphocytes B cells T cells Erythrocytes Platelets Neutrophils Monocytes Eosinophils Basophils Cardiovascular diseases Cardiovascular Disease Disorders of the heart and the blood vessels Account for more than half the deaths in the United States Atherosclerosis Atherosclerosis Caused by the buildup of plaque deposits within arteries Connective tissue Smooth muscle Endothelium Plaque (a) Normal artery 50 µm (b) Partly clogged artery 250 µm 4
Heart ahack Death of cardiac muscle Bssue Stroke Heart AHacks and Stroke ResulBng from blockage of one or more coronary arteries Death of nervous Bssue in the brain Usually resulbng from rupture or blockage of arteries in the head Treatment and Diagnosis of Cardiovascular Disease Cholesterol Major contributor to atherosclerosis Low density lipoproteins (LDLs) Associated with plaque formabon; these are bad cholesterol High density lipoproteins (HDLs) Reduce the deposibon of cholesterol; these are good cholesterol The proporbon of LDL relabve to HDL can be decreased by exercise, not smoking, and avoiding foods with trans fats Treatment and Diagnosis of Cardiovascular Disease Hypertension, or high blood pressure Promotes atherosclerosis and increases the risk of heart aback and stroke Can be reduced by dietary changes, exercise, and/or medicabon Classification Systolic pressure Diastolic pressure mmhg kpa mmhg kpa Normal 90 119 12 15.9 60 79 8.0 10.5 Prehypertension 120 139 16.0 18.5 80 89 10.7 11.9 Stage 1 140 159 18.7 21.2 90 99 12.0 13.2 Stage 2 160 21.3 100 13.3 Isolated systolic hypertension 140 18.7 <90 <12.0 Source: American Heart Association (2003).[5] 5
Respiratory System Gas exchange Supplies oxygen for cellular respirabon and disposes of carbon dioxide Gases Par?al Pressure Gradients in Gas Exchange Diffuse down pressure (concentrabon) gradients as a result of differences in parbal pressure In the lungs External RespiraBon Other organs Internal RespiraBon Par?al pressure Pressure exerted by a parbcular gas in a mixture of gases Par?al Pressure Gradients in Gas Exchange A gas diffuses from a region of higher parbal pressure to a region of lower parbal pressure In the lungs and Bssues O 2 and CO 2 diffuse from where their parbal pressures are higher to where they are lower 6
Respiratory Media Animals 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 Animals Respiratory Surfaces Require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium, either air or water Occurs by diffusion Respiratory surfaces vary by animal Can include the outer surface, skin, gills, tracheae, and lungs Gills Gills in Aqua?c Animals Ougoldings of the body that 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 7
Ven?la?on Moves the respiratory medium over the respiratory surface AquaBc animals Move through water or move water over their gills for venblabon Fish gills Gills in Aqua?c Animals Use a countercurrent exchange system Where blood flows in the opposite direcbon to water passing over the gills Blood is always less saturated with O 2 than the water it meets Fig. 42-22 Anatomy of gills Gill arch Oxygen-poor blood Oxygen-rich blood Fluid flow through gill filament Lamella Gill arch Gill filament organization Water flow Operculum Blood vessels Water flow between lamellae Blood flow through capillaries in lamella Countercurrent exchange P O2 (mm Hg) in water 150 120 90 60 30 Gill filaments Net diffusion of O 2 from water to blood 140 110 80 50 20 P O2 (mm Hg) in blood Tracheal system Tracheal Systems in Insects Consists of Bny branching tubes that penetrate the body Tracheal tubes supply O 2 directly to body cells Respiratory and circulatory systems are separate Larger insects must venblate their tracheal system to meet O 2 demands 8
Fig. 42-23 Air sacs Tracheae External opening Tracheoles Mitochondria Muscle fiber Body cell Tracheole Air sac Trachea Air Body wall 2.5 µm Lungs Lungs An infolding 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 Mammalian Respiratory Systems: A Closer Look Air inhaled through the nostrils passes through Pharynx Larynx Trachea Bronchi Bronchioles Alveoli where gas exchange occurs Exhaled air passes over the vocal cords to create sounds SecreBons called surfactants coat the surface of the alveoli 9
Fig. 42-24 Branch of pulmonary vein (oxygen-rich blood) Branch of pulmonary artery (oxygen-poor blood) Terminal bronchiole Pharynx Nasal cavity Larynx (Esophagus) Trachea Left lung Alveoli Right lung Bronchus Bronchiole Diaphragm Heart SEM Colorized 50 µm 50 µm SEM How an Amphibian Breathes Posi?ve pressure breathing Amphibian lung venblabon Air drawn into oral cavity Nostrils close Floor of oral cavity raised Forces air down the trachea How a Mammal Breathes Nega?ve pressure breathing Diaphragm contracts, pulling down Lung volume increases Creates negabve pressure Tidal volume Volume of air inhaled with each relaxed breath 10
How a Mammal Breathes Vital Capacity Maximum inhalabon volume Ajer exhalabon, a residual volume of air remains in the lungs 11