Heart and Respiratory Systems

1. Heart and Respiratory Systems

2. Blood links every system of the body • Functions of Blood • Transportation of dissolved gases, nutrients, hormones and metabolic wastes • Carries hormones, carbon dioxide and oxygen, carries waste to kidneys • Regulation of the pH and ion composition of interstitial fluids throughout the body • Carries ions like calcium or potassium, absorbs and neutralizes acids like lactic acid • Restricts and eventually stops blood/fluid loss at injury sites • Responds to breaks in vessel walls by starting the process of blood clotting

3. Defends against toxins and pathogens • White blood cell, migrate into body tissues to fight infections and remove debris, delivers antibodies that attack invading organisms • Stabilizes the temperature of the body • Absorbs heat generated by skeletal muscles and redistributes it to other tissues. When the core temperature is high blood vessels in the skin surface dilate, when it is too low the same vessels constrict causing the blood to flow to critical structures like the brain and kidneys • More blood facts • Temperature of blood is roughly 100.4 degrees F (38 degrees C) • pH is slightly alkaline 7.35 – 7.45 • 5 times stickier , more cohesive and resistant to flow than water (viscosity) creating better interaction among the dissolved elements in the blood • Plasma contains dissolved proteins and formed elements • RBCs or erythrocytes, WBCs leukocytes, Platelets membrane-enclosed sacs of cytoplasm that contain enzymes and factors for blood clotting

4. Major contributors to osmotic pressure of plasma, transports lipids, steroid hormones Plasma Proteins Albumins 60% Globulins 35% Fibrinogen 4% Regulatory proteins <1% Transport ions, hormones, lipids, immune function Plasma Plasma proteins 7% Other solutes 1% Water 92% Transports organic and inorganic molecules, formed elements and heat Essential component of clotting, can be converted to insoluble fibrin Enzymes, proenzymes, hormones Other solutes Electrolytes Organic nutrients Organic wastes Na, K, Ca, + ions Cl HCO3 - ions Fatty acids, glucose, amino acids Urea, bilirubin Formed elements Platelets and WBCs 0.1% Red blood cells 99.9% Platelets White blood cells Red blood cells 99.9% The liver synthesizes 90% of plasma proteins , antibodies are produced by the plasma cells of the lymphatic system

5. Blood factoids Red blood cells take a terrible “beating” in their lives Squeezed, bounced of vessel walls, and bump into each other and other blood elements RBC life span is about 120 days About 3 million new RBCs enter circulation each second RBCs carry oxygen and carbon dioxide. These gasses attach themselves to the hemewhich hold an iron ion, but the interaction is weak so gasses are easily released when necessary. Usually RBCs are broken down in the blood and the polypeptide chains are filtered by the kidneys. Each heme molecule is stripped of its iron and converted to biliverdin (green color), than converted to bilirubin (yellow color) and absorbed by the liver and released in bile Globular proteins are converted back into amino acids . Along with iron, it is recycled to the myeloid tissue. 26 mg of iron are needed to produce hemoglobin a day

6. Factoids cont’d WBCs are larger than RBCs and have a nucleus and other organelles but lack hemoglobin. WBC use the blood stream for transportation but spend most of their lives in the tissues of organs. They squeeze between epithelial cells in capillary walls. Neutrophils, eosinophils and monocytes are capable of phagocytosis. Huge cells with large nuclei (called megakaryocytes) shed cytroplasm in small membrane enclosed packets. These packets are platelets the circulate for 9-12 days. For blood to clot is must have clotting factors, which include calcium ions and 11 different proteins that are converted from proenzymes. More blood info can be found in Chapter 11 of the text

7. Anatomy of the Heart Lies in the mediastinum which also contains the trachea, esophagus and thymus The heart lies to the left of the midline near the anterior chest wall, directly behind the sternum The apex of the heart lies along the diaphragm

8. CPR is possible The heart lies: under the sternum in front of vertebrae T 2 - T 8 Compressions occur when the ventricles are squeezed between the lower sternum and T 7 & 8

9. Covering and Layers Tissues of the Heart Built for strength and endurance Reduces friction

10. Size and Shape of the Heart An infant heart is about 1/130th of its total body weight An adult heart is about 1/300th of the adults body weight 310 g in the male 225g in the female Does body size affect heart size?

11. Three layers of the heart Epicardium covers the outer surface of the heart Serous membrane and underlying layer of loose connective tissue that is attached to the myocardium. Myocardium – muscular wall of the heart Contains cardiac muscle, blood vessels and nerves Wraps around the atria and in to the walls of the ventricles Endocardium Simple squamous epithelium that is continuous with the epithelial lining of the blood vessels

12. Chambers of the Heart Atria Ventricles

13. Valves of the heart Atrioventricular valves Tricuspid Mitral (bicuspid) Chordaetendineae Keeps the valves from turning inside out like an umbrella in the wind Semilunar Valves Pulmonary Aortic Regurgitation is the reason for a heart murmur Great pictures in your text page 396

14. Why are the walls of the left ventricle thicker than the right ventricle?

15. Heart contraction lasts 25-30 times longer than skeletal muscle contraction View heart contraction The contraction of the heart muscle is different than skeletal muscle. Because of this the heart can contract only about 200 times per minute. In cardiac muscle the refractory period continues until relaxation is underway. It cannot reach tetanus as skeletal muscle does. Refractory period

16. Heart factoids Cardiac Output= Stroke Volume x Heart Rate CO = SV x HR Average Cardiac Output is about 5.6L /min During exercise SV can double and HR can rise as much as 250% Cardiac Output can rise as much as 500% to 700% --as much as 30 L/minute. Aerobic exercise can increase both Stroke Volume and Heart Rate When these are increased the heart has more resting time. Cooler body temperatures slow down the HR because it slows the rate of depolarization at the SA node. Elevated body temperature causes the HR to speed up as when one has a fever. Could this be an advantage is some instances? The stretching of the heart muscle effects how hard the heart forcefully contracts. Therefore if more venous blood enters the heart the more it forcefully contracts.

17. Would increased venous return have an effect on stroke volume? If the semilunar valve on the right side of the heart were damaged, how would it interfere with blood flow? What prevents the AV valves from opening back into the atria? 4. Why is it important for the impulses from the atria to be delayed at the AV node before passing into the ventricles? 5. What causes the lubb-dubb sound of the heart that can be heard with a stethoscope? 6. Blood doping was temporarily widespread among competitive athletes. RBC were harvested several weeks before an athletic event and then given back to an athlete right before the event. The consequence is that the athlete’s heart is placed under a tremendous strain. However the raise of RBC can happen in a normal person. Can you describe an event that might raise one’s hematocrit?