Human Anatomy Class Quiz

Cardiovascular System Overview

• The cardiovascular system is a closed system of the heart and blood vessels.
• The heart pumps blood.
• Blood vessels allow blood to circulate to all parts of the body.
• The cardiovascular system delivers oxygen and nutrients, and removes carbon dioxide and other waste products.

Blood Components

• Blood is composed of 55% plasma and 45% cells.
• Plasma is 90% water, with ions, proteins, gases, nutrients, wastes, and hormones.
• Blood cells include red blood cells (RBCs), white blood cells (WBCs), and platelets.
• RBCs develop from stem cells in bone marrow.
• WBCs defend against infection and tumors.
• Platelets are cell fragments needed for blood clotting.

Blood Cell Formation

• Haematopoiesis is blood cell formation.
• It occurs in red bone marrow.
• Bone marrow locations include skull, pelvis, ribs, sternum, humerus, and femur.

Erythrocytes (Red Blood Cells)

• RBCs transport oxygen in the blood.
• They are biconcave discs, anucleate (no nucleus), and contain hemoglobin (iron-containing protein that binds to oxygen).
• RBC lifespan is 100-120 days.

Common Health Problems with RBCs

• Anemia: decrease in oxygen-carrying ability of blood, often due to low RBC count or deficient hemoglobin content.
• Sickle-cell disease: abnormal hemoglobin, a genetic disorder.

Leukocytes (White Blood Cells)

• WBCs defend against infection and tumors.
• They locate areas of tissue damage by responding to chemicals.
• WBC types include neutrophils, eosinophils, basophils, lymphocytes, and monocytes.
• Lymphocytes (T-cells, B-cells, NK cells) are important for immune function.

Common Health Problem with WBCs

• Leukemia: bone marrow cancer, characterized by an abnormal amount of WBCs.
• Treatment includes chemotherapy, radiotherapy, and stem cell transplant.

Platelets

• Platelets are cell fragments that are irregularly shaped.
• They are needed for blood clotting.

Functions of Blood

• Deliver oxygen and nutrients to body cells.
• Transport waste products from cells for elimination.
• Transport hormones.
• Maintain body temperature.
• Maintain blood pH (using buffers).
• Maintain blood volume.
• Prevent blood loss (through clotting).
• Prevent infection (through WBCs and antibodies).

Hemostasis: Stoppage of Bleeding

• Vascular spasm: constrict damaged blood vessels.
• Platelet plug: platelets stick to damaged site and release chemicals to attract more platelets.
• Coagulation: fibrin threads form a mesh that traps RBCs, leading to blood clotting.
• Clotting time: typically 3–6 minutes.

Clotting Factors

• The process involves various factors including fibrinogen, prothrombin, thromboplastin, and calcium ions.
• Several other clotting factors are involved and are identified with Roman numerals (I to XIII).

Blood Clotting Disorders

• Thrombus: blood clot in unbroken blood vessel.
• Embolus: a thrombus that breaks away and floats freely.
• Stroke (cerebral embolus).
• Heart attack (coronary thrombosis).
• Hemophilia: hereditary bleeding disorder, caused by lacking clotting factors.

Human Blood Groups

• Antigens: foreign substances that trigger an immune response.
• Antibodies: Y-shaped proteins secreted by WBCs that attach to antigens.
• Agglutination: clumping caused by antibodies binding to antigens on RBCs.
• ABO blood grouping: based on A, B, and O antigens, with corresponding antibodies.
• Rh factor: another system of human blood groups, which also has antibodies.

ABO Blood Grouping (Details)

• Blood types are identified by the presence or absence of A and B antigens on red blood cells (RBCs) .
• Plasma contains antibodies (i.e. anti-A, anti-B) that react with the opposing antigens.
• Different blood types have different combinations of antigens and antibodies.
• O is the most common blood type in the world.

Rh(+/-) Blood Grouping (Details)

• Rh factor (also known as RhD) is another system of human blood groups, with antibodies.
• Rh-positive individuals have RhD antigens.
• Rh-negative individuals lack RhD antigens.
• Hemolytic disease of the newborn can occur if an Rh-negative mother carries an Rh-positive fetus.

Heart Structure and Organization

• Location: thorax, between the lungs, in the mediastinum, with apex pointing to the left, around the 5th intercostal muscle
• Size: about the size of a fist
• Wall structure: fibrous pericardium (outer), serous pericardium (middle), pericardial fluid (inner), myocardium (muscle layer), endocardium (inner lining).
• Chambers: four – two atria (receiving chambers), two ventricles (discharging chambers).
• Heart valves: atrioventricular valves (tricuspid right, mitral/bicuspid left) and semilunar valves (pulmonary and aortic).

Operation of Heart Valves

• Flapping leaflets act as one-way inlets and outlets.
• Papillary muscles and chordae tendineae prevent backflow.

Heart Associated Great Vessels

• Aorta: leaves the left ventricle, carries oxygenated blood to the body.
• Pulmonary arteries: leave the right ventricle, carry deoxygenated blood to the lungs
• Vena cava: enters the right atrium, carries deoxygenated blood from the body
• Pulmonary veins: enter the left atrium, carry oxygenated blood from the lungs.

Coronary Circulation

• The heart has its own nourishing circulatory system.
• Coronary arteries supply blood to the myocardium.
• Cardiac veins drain blood away from the myocardium.
• Blood empties into coronary sinus, which empties into the right atrium.

Cardiac Cycle

• Diastole: heart muscle relaxes and refills wtih blood.
• Systole: contraction and pumping of blood.
• Five phases: atrial systole, early ventricular systole, ventricular systole, early ventricular diastole, and late ventricular diastole.

Cardiac Output

• The amount of blood pumped by the heart each minute.
• It's different for individuals, depending on body size, which also takes into account the amount of blood pumped with each beat.
• Normal resting values vary but is around 5 liters per minute.
• Activities such as running can multiply cardiac output significantly.

Stroke Volume (SV)

• Stroke volume is the volume of blood pumped by each ventricle during each heart contraction (systole).
• SV is the difference between end diastolic volume (EDV) and end systolic volume (ESV).
• Normal SV is approximately 70 ml.

Regulation of Heart Rate and Volume

• Heart rate increases during exercise, to efficiently distribute more oxygenated blood to the body.
• Stroke volume can increase if the heart contracts more forcefully.
• Stroke volume also increases if the amount of blood that fills the left ventricle before pumping is higher.

Blood Vessel Structure and Function

• Blood vessels have three layers: tunica intima (inner), tunica media (middle), and tunica externa (outer).
• Arteries carry blood away from the heart; have thick walls and narrow lumina (inside diameters).
• Veins carry blood to the heart; have thinner walls and wider lumina (inside diameters).
• Capillaries are extremely thin-walled (one cell layer) and are responsible for material exchange.

Differences Between Blood Vessels (summary)

• Arteries have thick walls, high pressure, narrow lumina, no valves, and large amounts of muscle and elastic fibres..
• Veins have thin walls, low pressure, wide lumina, and valves.
• Capillaries are extremely thin-walled, have very low pressure, and have extremely narrow lumina, and no valves and lacks significant muscle or elastic fibers

Blood Circulation (Pulmonary and Systemic)

• Pulmonary circulation: carries deoxygenated blood to the lungs and returns oxygenated blood to the heart.
• Systemic circulation: carries oxygenated blood to the body's tissues and returns deoxygenated blood to the heart.

Lymphatic System

• Components: lymphatic vessels, lymph nodes, lymphatic organs (tonsils, adenoids, spleen, thymus).
• Functions: return leaked blood to the bloodstream, part of the immune system (forming lymphocytes, filtering fluid for pathogens), helping with digestion absorption of fat.
• Circulation: lymphatic fluid moves through the lymphatic vessels (similar to veins).
• Lymph nodes (filters): located throughout the body.
• Drainage: lymph flows into lymphatic duct(s), which drain into veins near the heart.

Long-Term Blood Pressure Regulation

• Renin-angiotensin-aldosterone system (RAAS): regulates blood volume by increasing reabsorption of sodium and water.
• Antidiuretic hormone (ADH): increases water reabsorption in the kidneys, increasing blood volume and raising blood pressure.
• Other factors include natriuretic peptides (ANP), which promote sodium excretion, and prostaglandins, which act as vasodilators to control blood pressure, alongside nerve stimulation for blood pressure control.

Short-Term Blood Pressure Regulation

• Baroreceptors (in arch of aorta and carotid sinus) sense blood pressure changes.
• ANS (autonomic nervous system) regulates heart rate and cardiac contractility, responding according to changes in pressure.
• Increased arterial pressure: detected by baroreceptors.
  • This triggers parasympathetic fibers (vagus nerve) to reduce heart rate, lowering blood pressure.
• Decreased arterial pressure: detected by receptors.
  • This triggers sympathetic response to increase heart rate, increasing blood pressure.

Additional Notes

• Various diagrams are included for understanding the processes involved in different systems.