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Transportation

Transportation. Section 1: Blood. Cardiovascular system Includes: Fluid (blood) Includes ~75 trillion cells Series of conducting hoses (blood vessels) Pump (heart). Figure 17 Section 1 1. The Components of the Cardiovascular System. THE HEART.

tristram-davies
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Transportation

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  1. Transportation

  2. Section 1: Blood Cardiovascular system Includes: Fluid (blood) Includes ~75 trillion cells Series of conducting hoses (blood vessels) Pump (heart)

  3. Figure 17 Section 1 1 The Components of the Cardiovascular System THE HEART propels blood and maintains blood pressure. Heart BLOOD VESSELS distribute blood around the body. Capillaries Capillaries permit diffusion between blood and interstitial fluids. Arteries carry blood away from the heart to the capillaries. Artery Vein Veins return blood from capillaries to the heart. BLOOD distributes oxygen, carbon dioxide, and blood cells; delivers nutrients and hormones; transports waste products; and assists in temperature regulation and defense against disease.

  4. Section 1: Blood Functions of blood Transportation of dissolved gases, nutrients, hormones, and metabolic wastes Regulation of the pH and ion composition of interstitial fluids Restriction of fluid loss at injury sites Defense against toxins and pathogens Stabilization of body temperature

  5. Module 17.1: Blood components Blood Is a fluid connective tissue About 5 liters (5.3 quarts) in body 5–6 in males, 4–5 in females (difference mainly body size) Consists of: Plasma (liquid matrix) Formed elements (cells and cell fragments) Properties Temp is roughly 38°C (100.4°F) Is 5× more viscous than water (due to solid components) Is slightly alkaline (average pH 7.4)

  6. Module 17.1: Blood components Whole blood Term for removed blood when composition is unaltered May be fractionated or separated Plasma 46%–63% of blood volume Hematocrit (or packed cell volume [PCV]) Percentage of whole blood contributed by formed elements (99% of which are red blood cells) Average 47% for male (range 40%–54%) Average 42% for female (range 37%–47%)

  7. Module 17.1: Blood components Plasma Composition resembles interstitial fluid in many ways Exists because exchange of water, ions, and small solutes 92% water 7% plasma proteins 1% other solutes Primary differences Levels of respiratory gases (oxygen and carbon dioxide) Concentrations of dissolved proteins (cannot cross capillary walls)

  8. Module 17.1: Blood components Plasma proteins In solution rather than as fibers like other connective tissues Each 100 mL has ~7.6 g of protein ~5× that of interstitial fluid Large size and globular shapes prevent leaving bloodstream Liver synthesizes >90% of all plasma proteins

  9. Module 17.1: Blood components Plasma proteins (continued) Albumins ~60% of all plasma proteins Major contributors to plasma osmotic pressure Globulins ~35% of all plasma proteins Antibodies (immunoglobulins) that attack pathogens Transport globulins that bind ions, hormones, compounds Fibrinogen Functions in clotting and activate to form fibrin strands Many active and inactive enzymes and hormones

  10. Module 17.1: Blood components Plasma solutes Electrolytes Essential for vital cellular activities Major ions are Na+, K+, Ca2+, Mg2+, Cl–, HCO3–, HPO4–, SO42– Organic nutrients Used for cell ATP production, growth, and maintenance Includes lipids, carbohydrates, and amino acids Organic wastes Carried to sites of breakdown or excretion Examples: urea, uric acid, creatinine, bilirubin, NH4+

  11. Figure 17.1 1 Plasma (46–63%) Whole blood consists of Formed elements (37–54%)

  12. Module 17.1: Blood components Formed elements Platelets Small membrane-bound cell fragments involved in clotting White blood cells (WBCs) Also known as leukocytes (leukos, white + -cyte, cell) Participate in body’s defense mechanisms Five classes, each with different functions Red blood cells (RBCs) Also known as erythrocytes (erythros, red + -cyte, cell) Essential for oxygen transport in blood

  13. Module 17.1 Review a. Define hematocrit. b. Identify the two components constituting whole blood, and list the composition of each. c. Which specific plasma proteins would you expect to be elevated during an infection?

  14. Module 17.2: Red blood cells RBCs in blood Most numerous cell type in blood Roughly 1/3 of all cells in the body Red blood cell count (standard blood test) results Adult males: 4.5–6.3 million RBCs/1 µL or 1 mm3 of whole blood Adult females: 4.2–5.5 million RBCs/1 µL or 1 mm3 of whole blood One drop = 260 million RBCs

  15. Module 17.2: Red blood cells RBC characteristics Biconcave disc Average diameter ~8 µm Large surface area-to-volume ratio Greater exchange rate of oxygen Can form stacks (rouleaux) Facilitate smooth transport through small vessels Are flexible Allow movement through capillaries with diameters smaller than RBC (as narrow as 4 µm)

  16. Figure 17.2 1 LM x 450 Stained blood smear

  17. Figure 17.2 2 The size and biconcave shape of an RBC 7.2–8.4 μm 2.31–2.85 μm 0.45–1.16 μm RBCs Colorized SEM x 1800

  18. Figure 17.2 3 The advantages of the biconcave shape of RBCs Functional Aspects of Red Blood Cells • Large surface area-to-volume ration. Each RBC carries oxygen bound to intracellular proteins, and that oxygen must be absorbed or released quickly as the RBC passes through the capillaries. The greater the surface area per unit volume, the faster the exchange between the RBC’s interior and the surrounding plasma. The total surface area of all the RBCs in the blood of a typical adult is about 3800 square meters, roughly 2000 times the total surface area of the body. Rouleaux (stacks of RBCs) Blood vessels (viewed in longitudinal section) • RBCs can form stacks. Like dinner plates, RBCs can form stacks that ease the flow through narrow blood vessels. An entire stack can pass along a blood vessel only slightly larger than the diameter of a single RBC, whereas individual cells would bump the walls, bang together, and form logjams that could restrict or prevent blood flow. Nucleus of endothelial cell Red blood cell (RBC) • Flexibility. Red blood cells are very flexible and can bend and flex when entering small capillaries and branches. By changing shape, individual RBCs can squeeze through capillaries as narrow as 4 μm. LM x 1430 Sectional view of capillaries

  19. Module 17.2: Red blood cells RBC characteristics (continued) Lose most organelles including nucleus during development Cannot repair themselves and die in ~120 days Contain many molecules (hemoglobin) associated with primary function of carrying oxygen Each cell contains ~280 million hemoglobin (Hb) molecules Normal whole blood content (grams per deciliter) 14–18 dL (males), 12–16 dL (females) ~98.5% of blood oxygen attached to Hb in RBCs Rest of oxygen dissolved in plasma

  20. Module 17.2: Red blood cells Hemoglobin Protein with complex quaternary structure Each molecule has 4 chains (globular protein subunits) 2 alpha (α) chains 2 beta (β) chains Each chain contains a single heme pigment molecule Each heme (with iron) can reversibly bind one molecule of oxygen Forms oxyhemoglobin (HbO2) (bright red) Deoxyhemoglobin when not binding O2 (dark red)

  21. Figure 17.2 4

  22. Figure 17.2 5 The quaternary structure of hemoglobin β chain 1 α chain 1 Heme β chain 2 α chain 2

  23. Figure 17.2 6 The chemical structure of a heme unit Heme

  24. Module 17.2 Review a. Define rouleaux. b. Describe hemoglobin. c. Compare oxyhemoglobin with deoxyhemoglobin.

  25. Section 1: Heart Structure Location of the heart Near anterior chest wall, directly posterior to sternum Center lies slightly to the left of midline Entire heart is rotated slightly left

  26. Section 1: Heart Structure Gross anatomy Base (superior surface where major vessels attach) Apex (inferior pointed tip) Borders Superior border (formed by base) Right border (formed by right atrium) Left border (formed by left ventricle and small part of left atrium) Inferior border (formed mainly by inferior wall of right ventricle)

  27. Figure 18 Section 1 1 The location of the heart in the chest cavity Base 1 1 2 2 3 Ribs 3 4 4 5 5 Apex 6 6 7 7 8 8 9 9 10 10

  28. Figure 18 Section 1 2 An anterior view showing the borders of the heart Superior border Right border Left border Inferior border

  29. Module 18.1: Heart wall and tissue Layers of heart wall Epicardium (visceral pericardium) Covers surface of heart Serous membrane made of exposed mesothelium and underlying areolar tissue (attaching to myocardium) Parietal pericardium Not a heart wall layer but is continuous serousmembrane with visceral pericardium Lines pericardial cavity and fibrous pericardial sac

  30. Module 18.1: Heart wall and tissue Layers of heart wall (continued) Myocardium Middle, muscular layer forming atria and ventricles Contains cardiac muscle tissue, blood vessels, and nerves Concentric muscle tissue layers Form a figure-eight around the atria Superficial muscle layers wrap both ventricles Deep muscle layers form figure-eight around ventricles

  31. Figure 18.1 2 The direction of muscle bundles of the atrial and ventricular musculature Atrial musculature Ventricular musculature

  32. Module 18.1: Heart wall and tissue Layers of heart wall (continued) Endocardium Covering inner surfaces of heart, including valves Composed of simple squamous epithelial tissue and underlying areolar tissue Forms endothelium continuous with blood vessel endothelium

  33. Figure 18.1 1 A section of the heart showing its three layers: epicardium, myocardium, and endocardium Parietal Pericardium The serous membrane that forms the outer wall of the pericardial cavity; it and a dense fibrous layer form the pericardial sac surrounding the heart Pericardial cavity (contains serous fluid) Dense fibrous layer Areolar tissue Mesothelium Myocardium Muscular wall of the heart consisting primarily of cardiac muscle cells Epicardium Covers the outer surface of the heart; also called the visceral pericardium Mesothelium Areolar tissue Connective tissues Endocardium Covers the inner surfaces of the heart Endothelium Areolar tissue

  34. Module 18.1: Heart wall and tissue Cardiac muscle tissue Compared to skeletal muscle tissue Small cell size Single, centrally located nucleus Branching interconnections Specialized intercellular connections Intercalated discs

  35. Figure 18.1 3 A light micrograph showing the histological characteristics of cardiac muscle tissue Intercalated discs LM x 575 Cardiac muscle tissue

  36. Module 18.1: Heart wall and tissue Cardiac muscle tissue (continued) Found only in the heart Cells are striated due to organized myofibrils Almost totally dependent on aerobic metabolism for ATP Large numbers of mitochondria and myoglobin to store O2 Has large number of capillaries to supply nutrients and O2

  37. Module 18.1: Heart wall and tissue Intercalated discs Contain: Desmosomes Gap junctions Allow ions and molecules to move directly between cells Create direct electrical connection so an action potential can pass directly between cells Stabilize relative positions of adjacent cells Allow cells to “pull together” for maximum efficiency All cells to function “as one” (functional syncytium)

  38. Figure 18.1 4 – 5 The structure of cardiac muscle cells Size of a typical cardiac muscle cell: 10–20 μm in diameter and 50–100 μm in length Cardiac muscle cells, which feature organized myofibrils, aligned sarcomeres, and numerous mitochondria Intercalated disc (sectioned) Nucleus Mitochondria Bundles of myofibrils Intercalated disc The connection of cardiac muscle cells by intercalated discs, gap junctions, and desmosomes, forming a functional syncytium Gap junction Intercalated Disc Z lines bound to opposing cell membranes Desmosomes

  39. Module 18.1 Review a. From superficial to deep, name the layers of the heart wall. b. Describe how the cardiac muscle cells ‘talk’ to one another. c. Why is it important that cardiac tissue be richly supplied with mitochondria and capillaries?

  40. Module 18.2: Pericardial cavity Heart lies within pericardial cavity, a subdivision of the mediastinum Mediastinum also contains: Great vessels (entering and exiting the heart) Thymus Esophagus Trachea Because heart is closely associated with many organs, trauma can lead to fluid accumulation that can restrict heart movement (cardiac tamponade)

  41. Figure 18.2 1 – 3 Two views showing the location of the heart in the chest cavity The position and orientation of the heart relative to the major vessels and the ribs, sternum, and lungs A diagrammatic superior view of a partial dissection of the thoracic cavity showing the physical relationships among the components in the mediastinum Trachea Thyroid gland First rib (cut) Posterior mediastinum Esophagus Aorta (arch segment removed) Base of heart Right lung Left lung Left pulmonary artery Apex of heart Diaphragm Right pleural cavity Left pleural cavity Parietal pericardium (cut) Right lung Left lung Anterior view of chest cavity Left pulmonary vein Bronchus of lung Aortic arch Pulmonary trunk Right pulmonary artery Left atrium Right pulmonary vein Left ventricle Pericardial cavity Superior vena cava Epicardium Right atrium Pericardial sac Right ventricle Anterior mediastinum

  42. Module 18.2: Pericardial cavity Pericardial cavity and fluid Lined with parietal pericardium Continuous with visceral pericardium (like balloon with fist in it) Contains 10–15 mL of pericardial fluid secreted by membranes Acts as lubricant when heart beats Swelling of pericardial surfaces can occur with infection causing friction (pericarditis)

  43. Figure 18.2 1 The position and orientation of the heart relative to the major vessels and the ribs, sternum, and lungs Trachea Thyroid gland First rib (cut) Base of heart Right lung Left lung Apex of heart Diaphragm Parietal pericardium (cut) Anterior view of chest cavity

  44. Figure 18.2 2 Wrist (corresponds to base of heart) The positions of and relationship between the heart and the pericardial cavity Inner wall (corresponds to epicardium) The relationship between the heart and the pericardial cavity, which can be linked to a fist pressed into the center of a partially inflated balloon Air space (corresponds to pericardial cavity) Outer wall (corresponds to parietal pericardium) Balloon Base of heart The location of the pericardial cavity relative to the heart Cut edge of parietal pericardium Fibrous tissue of pericardial sac Parietal Pericardium Pericardial cavity containing pericardial fluid Areolar tissue Mesothelium Cut edge of epicardium Fibrous attachment to diaphragm Apex of heart

  45. Module 18.2 Review a. Define mediastinum. b. Describe the heart’s location. c. Why can cardiac tamponade be a life-threatening condition?

  46. Module 18.3: Heart surface anatomy Heart surface anoatomy Sulci (singular, sulcus) Surface grooves separating heart chambers Often with cardiac vessels covered with fat Anterior interventricular sulcus Anterior groove separating ventricles Posterior interventricular sulcus Posterior groove separating ventricles Coronary sulcus Separates atria from ventricles On posterior surface, contains coronary sinus (collects blood from myocardium and conveys to right atrium)

  47. Module 18.3: Heart surface anatomy Other surface features Auricles Expandable extensions of atria Ligamentum arteriosum Fibrous remnant of fetal connection between aorta and pulmonary trunk

  48. Figure 18.3 1 – 3 Two views of the anterior surface of the heart A diagrammatic view of the anterior surface of the heart A photograph of an anterior view of a heart from a preserved cadaver Ligamentum arteriosum Aortic arch Parietal pericardium Ascending aorta Ascending aorta Superior vena cava Pulmonary trunk Auricle of right atrium Superior vena cava Auricle of left atrium Pulmonary trunk Right atrium Right ventricle Auricle Auricle of left atrium Anterior interventricular sulcus Right atrium Coronary sulcus Fat Left ventricle Right ventricle Left ventricle Cadaver dissection, anterior view Coronary sulcus Anterior interventricular sulcus Anterior surface

  49. Module 18.3 Review b.Name and describe the shallow depressions and grooves found on the heart’s external surface. c. Which structures collect blood from the myocardium, and into which heart chamber does this blood flow?

  50. Module 18.4: Coronary circulation Coronary circulation Provides cardiac muscle cells with reliable supplies of oxygen and nutrients During maximum exertion, myocardial blood flow may increase to 9× resting levels Blood flow is continuous but not steady With left ventricular relaxation, aorta walls recoil (elastic rebound), which pushes blood into coronary arteries

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