Human Anatomy: Blood and Heart Study Notes

Study Notes

Human Anatomy: Blood and Heart Study Notes

Blood Function:
- Transportation of gases, nutrients, hormones, and waste products.
- Regulation of pH, body temperature, and osmotic pressure.
- Protection through clotting, white blood cells, and proteins.
Blood Characteristics:
- Volume: 8% of body weight (females: 4-5L, males: 5-6L)
- pH: 7.35 to 7.45
- Temperature: 38°C
Blood Components:
- Plasma (55%): Water, liquid extracellular matrix, proteins (albumins, globulins, fibrinogen), other solutes (electrolytes, nutrients, hormones, gases, waste).
- Formed Elements (45%): Cells and cell fragments (red blood cells, white blood cells, platelets).
Blood Cell Formation (Hematopoiesis):
- Red bone marrow is the primary site.
- Stem cells in red bone marrow reproduce and differentiate, forming all blood cells.
- Pluripotent stem cells differentiate into myeloid and lymphoid stem cells.
- Formed elements do not divide once they leave red bone marrow, except for lymphocytes.
- Cells enter the bloodstream through sinusoids.
Blood Cell Formation Regulation:
- Hematopoietic growth factors regulate differentiation and proliferation.
- Erythropoietin (EPO) from the kidney stimulates RBC production.
- Thrombopoietin (TPO) from the liver stimulates platelet production.
- Colony-stimulating factors (CSFs) and interleukins help with the formation of WBCs and other blood cells.
Red Blood Cells (RBCs/Erythrocytes):
- Structure: Biconcave, anucleate (no nucleus).
- Components: Hemoglobin (transports oxygen and carbon dioxide), lipids, ATP, carbonic anhydrase.
- Function: Transport oxygen and carbon dioxide.
- Normal Count: 4.8 x 10⁶/µL (female), 5.4 x 10⁶/µL (male).
- Disorders: Anemia
- Life cycle: Live for about 120 days, destroyed by macrophages in spleen and liver, broken down components are recycled.
Hemoglobin:
- Protein in RBCs.
- Composed of 4 globin molecules and 4 heme molecules.
- Transports oxygen and carbon dioxide.
- Iron is necessary for oxygen transport.
Erythropoiesis:
- RBC production begins in red bone marrow with proerythroblasts.
- Proerythroblasts develop into mature RBCs within 1-2 days.
- Regulation of erythropoiesis through negative feedback, controlled by the amount of oxygen delivery to tissues (low oxygen level causes release of EPO to produce more RBCs).
White Blood Cells (WBCs/Leukocytes):
- Types: Granular (neutrophils, eosinophils, basophils) and agranular (lymphocytes, monocytes).
- Functions: Combat invaders through phagocytosis and immune responses.
Platelets/Thrombocytes:
- Cell fragments from megakaryocytes in red bone marrow.
- Disc-shaped and contain vesicles, but no nucleus.
- Important in preventing blood loss by forming platelet plugs and promoting clot formation.
Blood Groups:
- Determined by antigens (agglutinogens) on RBC surface.
- Antibodies (agglutinins) in plasma can bind to antigens, causing agglutination or hemolysis.
- ABO and Rh blood groups are common examples.
Heart Location and Pericardium:
- Located in the mediastinum, between the lungs, about 2/3 to the left of the midsternal line and 1/3 to the right.
- Pericardium is a membrane around the heart, protecting and confining it while allowing free movement. The two main parts are the fibrous pericardium and the serous pericardium, which consists of a parietal and visceral layers.
Heart Walls:
- Three layers: Epicardium (outermost, visceral layer of serous pericardium). Myocardium (middle, cardiac muscle). Endocardium (innermost, endothelium).
Heart Chambers:
- Two atria (receiving chambers) and two ventricles (pumping chambers). Right atrium and ventricle handle deoxygenated blood and left atrium and ventricle handle oxygenated blood.
- Blood moves between atria and ventricles through atrioventricular valves. Blood moves between ventricles and arteries through semilunar valves.
Heart Valves:
- AV (atrioventricular) valves (tricuspid, bicuspid/mitral) control blood flow between atria and ventricles. Regulate blood flow and prevent backflow from ventricles to atria.
- Semilunar valves (aortic, pulmonary) control blood flow from ventricles into arteries. Prevent backflow from arteries into ventricles.
Circulation: - Two main circuits: Pulmonary circulation moves blood between the heart and lungs for gas exchange. Systemic circulation moves blood between the heart and the rest of the body.
Coronary Circulation:
- Network of blood vessels that supply blood to the heart muscle, originating from the ascending aorta.
- Main coronary arteries branch off into smaller branches (including posterior interventricular branch, marginal branch, anterior interventricular branch, circumflex branch).
- Coronary veins empty into the coronary sinus and then into the right atrium for drainage.