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Giraffes have – Very strong hearts – Higher blood pressure – Sinuses that function like check valves to lower pressure to head when bending down – Valves in veins of legs to keep blood moving upward Copyright © 2009 Pearson Education, Inc. Blood and respiratory gasses are passed through which organ system? Circulatory system All cells need – Nutrients – Gas exchange – Removal of wastes Diffusion alone is inadequate for large and complex bodies Copyright © 2009 Pearson Education, Inc. ◦ 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. 1. Open circulatory systems – Arthropods and many molluscs – Heart pumps blood through open-ended vessels – Cells directly bathed in blood Tubular heart Pores Copyright © 2009 Pearson Education, Inc. 2. 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 Arteriole Capillary beds Artery (O2-rich blood) Venule Vein Gill capillaries Copyright © 2009 Pearson Education, Inc. Artery (O2-poor blood) Atrium Ventricle Heart Land vertebrates have double circulation Lung capillaries – Separate pulmonary (lung) and systemic (body) circuits – Two circuits that do not mix – Right side pumps blood from body to lungs – Left side pumps blood from lungs to body Pulmonary circuit A V Right A V Left Systemic circuit Systemic capillaries Copyright © 2009 Pearson Education, Inc. ◦Four-chambered hearts Lung capillaries – Crocodilians, birds, mammals – Two atria and two ventricles – Higher blood pressure – Supports more efficient movement of blood Pulmonary circuit A A V V Left Right Systemic circuit Systemic capillaries THE HUMAN CARDIOVASCULAR SYSTEM Copyright © 2009 Pearson Education, Inc. 8 Superior vena cava Capillaries of head, chest, and arms Pulmonary artery Pulmonary artery Capillaries of right lung 9 Capillaries of left lung Aorta 2 7 2 3 3 4 5 10 4 Pulmonary vein Right atrium 6 1 9 Pulmonary vein Left atrium Left ventricle Right ventricle Inferior vena cava Aorta 8 Capillaries of abdominal region and legs ◦ The mammalian heart – Two thin-walled atria that – Pump blood – To ventricles – Two thick-walled ventricles that – Pump blood Right atrium To lung To lung Left atrium From lung From lung Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricula (AV) valve – To lungs and all other body regions Left Right ventricle ventricle Copyright © 2009 Pearson Education, Inc. ◦ During diastole, blood flows Veins heart ◦ During systole, blood flows Atria ventricles 1 Heart is relaxed. 2 Atria contract. Semilunar valves closed 0.1 sec Systole AV valves are open. 0.3 sec 0.4 sec Semilunar valves are open. Diastole AV valves closed Copyright © 2009 Pearson Education, Inc. 3 Ventricles contract. ◦ 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 (SA node) – Sets the rate of heart contractions – Generates electrical signals in atria ◦ The AV node – Relays these signals to the ventricles Copyright © 2009 Pearson Education, Inc. Pacemaker (SA node) AV node Specialized muscle fibers Right atrium Apex 1 Pacemaker generates signals to contract ECG 2 Signals spread through atria and are delayed at AV node 3 Signals relayed to apex of heart 4 Signals spread through ventricle ◦ An electrocardiogram (ECG or EKG) – Records electrical changes in heart ◦ Heart rate normally adjusts to body needs ◦ Abnormal rhythms may occur in a heart attack Copyright © 2009 Pearson Education, Inc. Heart A heart attack is damage to cardiac muscle – Typically from a blocked coronary artery Superior vena cava Pulmonary artery Right coronary artery Copyright © 2009 Pearson Education, Inc. Aorta Left coronary artery Blockage Dead muscle tissue Stroke – Death of brain tissue from blocked arteries in the head Copyright © 2009 Pearson Education, Inc. Atherosclerosis – Plaques develop inside inner walls of blood vessels – Plaques narrow blood vessels – Blood flow is reduced Connective tissue Smooth muscle Epithelium Copyright © 2009 Pearson Education, Inc. Plaque 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 Red blood cell Capillary Copyright © 2009 Pearson Education, Inc. Nuclei of smooth muscle cells Capillary Interstitial fluid Tissue cell Diffusion of molecules 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 Copyright © 2009 Pearson Education, Inc. Tissue cells Blood pressure Interstitial fluid Osmotic pressure Osmotic pressure Arterial end of capillary Net fluid movement out Blood pressure Net fluid movement in Venous end of capillary Arteries and veins – Lined by single layer of epithelial cells; smooth muscle in walls – Veins have one-way valves that restrict backward flow Epithelium Epithelium Smooth muscle Connective tissue Capillary Basal lamina Valve Epithelium Smooth muscle Connective tissue Artery Vein Arteriole Copyright © 2009 Pearson Education, Inc. Venule – Pressure from muscle contractions – Squeezes veins – One-way valves limit blood flow to one direction, towards heart Copyright © 2009 Pearson Education, Inc. Direction of blood flow in vein Valve (open) Skeletal muscle Valve (closed) – Deep Vein Thrombosis (DVT) – Blood pools deep within body- usually lower leg or thigh – Clot can form- travel to lungs- pulmonary embolism Copyright © 2009 Pearson Education, Inc. – – – – – Maintain healthy weight Don’t smoke Stretch or move legs on long flights or car rides Compression garments Blood thinners Copyright © 2009 Pearson Education, Inc. ◦ Blood pressure – The force blood exerts on vessel walls – Depends on – Cardiac output – Resistance of vessels – Decreases as blood moves away from heart Copyright © 2009 Pearson Education, Inc. Pressure (mm Hg) 120 100 80 60 40 20 0 Systolic pressure Diastolic pressure Venae cavae Veins Venules Capillaries Arterioles Arteries 50 40 30 20 10 0 Aorta Velocity (cm/sec) Relative sizes and numbers of blood vessels Blood pressure is – Highest in ________ – Lowest in _________ Blood pressure is measured as – Systolic pressure—caused by ventricular contraction – Diastolic pressure—low pressure between contractions Copyright © 2009 Pearson Education, Inc. 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 120 120 Rubber cuff inflated with air Artery 1 Copyright © 2009 Pearson Education, Inc. Pressure in cuff at 70 Pressure in cuff at 120 120 70 Sounds audible in stethoscope Artery closed 2 3 Sounds stop 4 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. STRUCTURE AND FUNCTION OF BLOOD Copyright © 2009 Pearson Education, Inc. Plasma is about 90% water Plasma contains – Various inorganic ions – Proteins, nutrients – Wastes, gases – Hormones Copyright © 2009 Pearson Education, Inc. Plasma (55%) Constituent Major functions Water Solvent for carrying other substances Ions (blood electrolytes) Osmotic balance, pH buffering, and maintaining ion concentration of interstitial fluid Sodium Potassium Calcium Magnesium Chloride Bicarbonate Plasma proteins Osmotic balance and pH buffering Fibrinogen Clotting Immunoglobulins (antibodies) Defense Substances transported by blood Nutrients (e.g., glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Centrifuged blood sample ◦ Red blood cells (erythrocytes) – Transport O2 bound to hemoglobin ◦ White blood cells (leukocytes) – Function inside and outside the circulatory system – Fight infections and cancer ◦ Platelets Copyright © 2009 Pearson Education, Inc. Cellular elements (45%) Cell type Functions Number 3 per µL (mm ) of blood Erythrocytes (red blood cells) 5–6 million Centrifuged blood sample Leukocytes 5,000–10,000 (white blood cells) Transport of oxygen (and carbon dioxide) Defense and immunity Lymphocyte Basophil Eosinophil Monocyte Neutrophil Platelets 250,000– 400,000 Blood clotting Plasma (55%) Constituent Major functions Water Solvent for carrying other substances Ions (blood electrolytes) Osmotic balance, pH buffering, and maintaining ion concentration of interstitial fluid Sodium Potassium Calcium Magnesium Chloride Bicarbonate Plasma proteins Cellular elements (45%) Cell type Functions Number per µL (mm3) of blood Erythrocytes (red blood cells) 5–6 million Centrifuged blood sample Leukocytes 5,000–10,000 (white blood cells) Transport of oxygen (and carbon dioxide) Defense and immunity Osmotic balance and pH buffering Fibrinogen Clotting Immunoglobulins (antibodies) Defense Substances transported by blood Nutrients (e.g., glucose, fatty acids, vitamins) Waste products of metabolism Respiratory gases (O2 and CO2) Hormones Lymphocyte Basophil Eosinophil Neutrophil Platelets Monocyte 250,000– 400,000 Blood clotting ◦ Function: ◦ If too few: – Anemia: abnormally low amounts of hemoglobin or red blood cells – Causes fatigue due to lack of oxygen in tissues Copyright © 2009 Pearson Education, Inc. Function: Clot formation during tissue damage ◦ When a blood vessel is damaged – Platelets help trigger the conversion of fibrinogen to fibrin – Fibrin forms a net with cells (clot) that plugs the leak Copyright © 2009 Pearson Education, Inc. 1 Platelets adhere to exposed connective tissue Epithelium Connective tissue Platelet 1 Platelets adhere to exposed connective tissue 2 Platelet plug forms Epithelium Connective tissue Platelet Platelet plug 1 Platelets adhere to exposed connective tissue 2 Platelet plug forms 3 Epithelium Connective tissue Platelet Platelet plug Fibrin clot traps blood cells