Copyright © 2009 Pearson Education, Inc. MECHANISMS OF INTERNAL TRANSPORT

Copyright © 2009 Pearson Education, Inc Circulatory systems facilitate exchange with all body tissues  All cells need –Nutrients –Gas exchange –Removal of wastes  Diffusion alone is inadequate for large and complex bodies

Copyright © 2009 Pearson Education, Inc Circulatory systems facilitate exchange with all body tissues  An internal transport system assists diffusion by moving materials between –Surfaces of the body –Internal tissues

Copyright © 2009 Pearson Education, Inc Circulatory systems facilitate exchange with all body tissues  A gastrovascular cavity in cnidarians and flatworms serves –Digestion –Distribution of substances  Most animals use a circulatory system –Blood –Heart –Blood vessels

Copyright © 2009 Pearson Education, Inc Circulatory systems facilitate exchange with all body tissues  Open circulatory systems –Arthropods and many molluscs –Heart pumps blood through open-ended vessels –Cells directly bathed in blood

Pores Tubular heart

Copyright © 2009 Pearson Education, Inc Circulatory systems facilitate exchange with all body tissues  Closed circulatory systems –Vertebrates, earthworms, squids, octopuses –Blood stays confined to vessels –A heart pumps blood through arteries to capillaries –Veins return blood to heart

Capillary beds Artery (O 2 -rich blood) Arteriole Artery (O 2 -poor blood) Heart Ventricle Atrium Vein Venule Gill capillaries

Copyright © 2009 Pearson Education, Inc EVOLUTION CONNECTION: Vertebrate Cardiovascular systems reflect evolution  Two-chambered heart –Fish –Pumps blood in a single circuit –From gill capillaries –To systemic capillaries –Back to heart

Gill capillaries Heart: Ventricle (V) Atrium (A) Systemic capillaries

Copyright © 2009 Pearson Education, Inc EVOLUTION CONNECTION: Vertebrate Cardiovascular systems reflect evolution  Land vertebrates have double circulation –Separate pulmonary and systemic circuits  Three-chambered hearts –Amphibians, turtles, snakes, lizards –Two atria –One undivided ventricle –Permits blood diversion away from lungs when diving –But some blood from body and lungs mixes in the ventricle when not diving

Lung and skin capillaries Pulmocutaneous circuit V Right Systemic capillaries AA Left Systemic circuit

Copyright © 2009 Pearson Education, Inc EVOLUTION CONNECTION: Vertebrate Cardiovascular systems reflect evolution  Four-chambered hearts –Crocodilians, birds, mammals –Two atria and two ventricles –Two circuits that do not mix –Right side pumps blood from body to lungs –Left side pumps blood from lungs to body –Higher blood pressure –Supports more efficient movement of blood –Needed in endothermic animals

Lung capillaries Pulmonary circuit V Right Systemic capillaries AA Left Systemic circuit V

Copyright © 2009 Pearson Education, Inc. THE HUMAN CARDIOVASCULAR SYSTEM

Copyright © 2009 Pearson Education, Inc The human cardiovascular system illustrates the double circulation of mammals  Blood flow through the double circulatory system of humans Animation: Path of Blood Flow in Mammals

Superior vena cava Pulmonary artery Capillaries of right lung Aorta Pulmonary vein 9 Right atrium Inferior vena cava Right ventricle Pulmonary artery Capillaries of left lung Aorta Pulmonary vein Left atrium Left ventricle 2 7 Capillaries of head, chest, and arms Capillaries of abdominal region and legs

Copyright © 2009 Pearson Education, Inc The human cardiovascular system illustrates the double circulation of mammals  The mammalian heart –Two thin-walled atria that –Pump blood –To ventricles –Thick-walled ventricles that –Pump blood –To lungs and all other body regions

Right atrium To lung From lung Semilunar valve Atrioventricular (AV) valve Left atrium To lung From lung Semilunar valve Atrioventricular (AV) valve Right ventricle Left ventricle

Copyright © 2009 Pearson Education, Inc The heart contracts and relaxes rhythmically  During diastole, blood flows –From veins –Into heart chambers  During systole, blood flows –From atria –Into ventricles

Semilunar valves closed 1 Heart is relaxed. AV valves are open. Diastole 0.4 sec

Semilunar valves closed 1 Heart is relaxed. AV valves are open. Diastole 0.4 sec 2 Atria contract. Systole 0.1 sec

Semilunar valves closed 1 Heart is relaxed. AV valves are open. Diastole 0.4 sec 2 Atria contract. Systole 0.1 sec Semilunar valves are open. 3 Ventricles contract. AV valves closed 0.3 sec

Copyright © 2009 Pearson Education, Inc The heart contracts and relaxes rhythmically  Cardiac output –Amount of blood/minute pumped into systemic circuit  Heart rate –Number of beats/minute  Heart valves –Prevent the backflow of blood  Heart murmur –A defect in one or more heart valves

Copyright © 2009 Pearson Education, Inc The pacemaker sets the tempo of the heartbeat  The pacemaker (SA node) –Sets the rate of heart contractions –Generates electrical signals in atria  The AV node –Relays these signals to the ventricles

Pacemaker (SA node) AV node Right atrium 1 Pacemaker generates signals to contract 2 Signals spread through atria and are delayed at AV node ECG 3 Signals relayed to apex of heart 4 Signals spread through ventricle Apex Specialized muscle fibers

Copyright © 2009 Pearson Education, Inc The pacemaker sets the tempo of the heartbeat  An electrocardiogram (ECG) –Records electrical changes in heart  Heart rate normally adjusts to body needs  Abnormal rhythms may occur in a heart attack –External defibrillator can restore rhythm –Implanted artificial pacemakers can trigger normal rhythms

Heart

Copyright © 2009 Pearson Education, Inc CONNECTION: What is a heart attack?  A heart attack is damage to cardiac muscle –Typically from a blocked coronary artery  Stroke –Death of brain tissue from blocked arteries in the head

Blockage Dead muscle tissue Right coronary artery Superior vena cava Pulmonary artery Aorta Left coronary artery

Copyright © 2009 Pearson Education, Inc CONNECTION: What is a heart attack?  Atherosclerosis –Plaques develop inside inner walls of blood vessels –Plaques narrow blood vessels –Blood flow is reduced

Plaque Epithelium Connective tissue Smooth muscle

Copyright © 2009 Pearson Education, Inc The structure of blood vessels fits their functions  Arteries and veins –Lined by single layer of epithelial cells –Smooth muscle in walls can reduce blood flow –Elastic fibers permit recoil after stretching –Veins have one-way valves that restrict backward flow

Connective tissue Capillary Venule Smooth muscle Arteriole ArteryVein Valve Epithelium Basal lamina Epithelium Smooth muscle Epithelium Connective tissue

Copyright © 2009 Pearson Education, Inc The structure of blood vessels fits their functions  Capillaries –Thin walls—a single layer of epithelial cells –Narrow—blood cells flow in a single file –Increase surface area for gas and fluid exchange

Nuclei of smooth muscle cells Red blood cell Capillary

Diffusion of molecules Capillary Interstitial fluid Tissue cell

Copyright © 2009 Pearson Education, Inc Blood pressure and velocity reflect the structure and arrangement of blood vessels  Blood pressure –The force blood exerts on vessel walls –Depends on –Cardiac output –Resistance of vessels –Decreases as blood moves away from heart

Systolic pressure Diastolic pressure Relative sizes and numbers of blood vessels Pressure (mm Hg) Velocity (cm/sec) Aorta Venae cavae Arteries CapillariesVenulesVeinsArterioles

Copyright © 2009 Pearson Education, Inc Blood pressure and velocity reflect the structure and arrangement of blood vessels  Blood pressure is –Highest in arteries –Lowest in veins  Blood pressure is measured as –Systolic pressure—caused by ventricular contraction –Diastolic pressure—low pressure between contractions

Copyright © 2009 Pearson Education, Inc Blood pressure and velocity reflect the structure and arrangement of blood vessels  How does blood travel against gravity, up legs? –Pressure from muscle contractions –Between two muscles –Between muscles and bone or skin –Squeezes veins –One-way valves limit blood flow to one direction, towards heart

Direction of blood flow in vein Valve (open) Skeletal muscle Valve (closed)

Copyright © 2009 Pearson Education, Inc CONNECTION: Measuring blood pressure can reveal cardiovascular problems  Hypertension is a serious cardiovascular problem –Consistent pressures above either –140 systolic –90 diastolic

Typical blood pressure 120 systolic 70 diastolic Pressure in cuff above Rubber cuff inflated with air Artery closed Artery 1 2 Pressure in cuff at Sounds audible in stethoscope 3 70 Sounds stop 4 Pressure in cuff at 70

Copyright © 2009 Pearson Education, Inc CONNECTION: Measuring blood pressure can reveal cardiovascular problems  Hypertension causes –Heart to work harder, weakening heart over time –Increased plaque formation from tiny ruptures –Increased risk of blood clot formation  Hypertension can cause –Heart attacks –Strokes –Kidney failure

Copyright © 2009 Pearson Education, Inc Smooth muscle controls the distribution of blood  Blood flow through capillaries –Is restricted by smooth muscle sphincters –Only about 5–10% of capillaries are open at one time

Capillaries Thoroughfare channel Precapillary sphincters Venule Sphincters relaxed Thoroughfare channel VenuleArteriole 2 1 Sphincters contracted Arteriole

Copyright © 2009 Pearson Education, Inc Capillaries allow the transfer of substances through their walls  Capillaries have very thin walls  Substances can cross through these thin walls –Between blood and interstitial fluids

Nucleus of epithelial cell Capillary lumen Interstitial fluid Capillary wall Muscle cell Clefts between the epithelial cells of the capillary wall

Copyright © 2009 Pearson Education, Inc Capillaries allow the transfer of substances through their walls  Blood and interstitial fluid exchange substances –By diffusion –By pressure flow through clefts between epithelial cells  Blood pressure forces fluid out of capillaries at the arterial end  Osmotic pressure draws in fluid at the venous end

Tissue cells Osmotic pressure Interstitial fluid Net fluid movement in Blood pressure Osmotic pressure Venous end of capillary Arterial end of capillary Blood pressure Net fluid movement out

Copyright © 2009 Pearson Education, Inc. STRUCTURE AND FUNCTION OF BLOOD

Copyright © 2009 Pearson Education, Inc Blood consists of red and white blood cells suspended in plasma  Plasma is about 90% water  Plasma contains –Various inorganic ions –Proteins, nutrients –Wastes, gases –Hormones

Copyright © 2009 Pearson Education, Inc Blood consists of red and white blood cells suspended in plasma  Red blood cells (erythrocytes) –Transport O 2 bound to hemoglobin  White blood cells (leukocytes) –Function inside and outside the circulatory system –Fight infections and cancer

Plasma (55%) Constituent Osmotic balance, pH buffering, and maintaining ion concentration of interstitial fluid Solvent for carrying other substances Water Ions (blood electrolytes) Major functions Sodium Potassium Calcium Magnesium Chloride Bicarbonate Plasma proteins ClottingFibrinogen Osmotic balance and pH buffering DefenseImmunoglobulins (antibodies) Substances transported by blood Nutrients (e.g., glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O 2 and CO 2 ) Hormones Cellular elements (45%) Centrifuged blood sample Number per µL (mm 3 ) of blood Cell typeFunctions Erythrocytes (red blood cells) 5–6 million Transport of oxygen (and carbon dioxide) Leukocytes (white blood cells) Basophil Lymphocyte Defense and immunity Eosinophil 5,000–10, ,000– 400,000 NeutrophilMonocyte Blood clotting Platelets

Copyright © 2009 Pearson Education, Inc Blood clots plug leaks when blood vessels are injured  The blood-clotting process –Platelets adhere to exposed connective tissue –Platelets form a plug –Platelets help trigger the conversion of fibrinogen to fibrin –A fibrin clot traps blood cells

Platelets adhere to exposed connective tissue 1 Epithelium Connective tissue Platelet

Platelets adhere to exposed connective tissue 1 Epithelium Connective tissue Platelet Platelet plug forms 2 Platelet plug

Platelets adhere to exposed connective tissue 1 Epithelium Connective tissue Platelet Platelet plug forms 2 Platelet plug Fibrin clot traps blood cells 3

Copyright © 2009 Pearson Education, Inc CONNECTION: Too few or too many red blood cells can be unhealthy  Anemia –Abnormally low amounts of hemoglobin or red blood cells –Causes fatigue due to lack of oxygen in tissues

Copyright © 2009 Pearson Education, Inc CONNECTION: Too few or too many red blood cells can be unhealthy  Hormone erythropoietin (EPO) –Regulates red blood cell production  Some athletes artificially increase red blood cell production by injecting erythropoietin –Can lead to –Clotting –Stroke –Heart failure –Death

Copyright © 2009 Pearson Education, Inc CONNECTION: Stem cells offer a potential cure for blood cell diseases  Stem cells divide in bone marrow –To produce all the types of blood cells throughout life –Are used to treat some blood disorders

Multipotent stem cell Lymphoid stem cell Myeloid stem cells Erythrocytes Platelets Eosinophils Basophils Neutrophils Monocytes Lymphocytes

Copyright © 2009 Pearson Education, Inc CONNECTION: Stem cells offer a potential cure for blood cell diseases  Leukemia is cancer of white blood cells –Leukemia results in extra leukocytes that do not function properly –Leukemia is usually fatal unless treated –Some treatments –Destroy all bone marrow in the patient –Transplant new bone marrow from a donor with similar bone marrow

Capillary Epithelium Valve Basement membrane Connective tissue Smooth muscle VeinArtery

a. c. d. e. f. g. h. i. b. p. o. n. m. l. k. j.

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Copyright © 2009 Pearson Education, Inc. You should now be able to 1.Explain how the circulatory systems of a giraffe and snake resist gravity 2.Describe the general need for and functions of a circulatory system 3.Compare the structures and functions of gastrovascular cavities, open circulatory systems, and closed circulatory systems 4.Compare the circulatory systems of a fish, frog, and mammal

Copyright © 2009 Pearson Education, Inc. You should now be able to 5.Explain how heartbeats are controlled 6.Describe the causes and consequences of a heart attack and cardiovascular disease 7.Relate the structure of blood vessels to their functions 8.Describe the components of blood and their functions

Copyright © 2009 Pearson Education, Inc. You should now be able to 9.Describe the process of blood clotting 10.Describe the causes and treatments for leukemia