Animal Circulatory Systems

Transport of Essential Materials

• The gastrovascular cavity diffuses gases and oxygen.
• Open circulatory systems pump fluid through open-ended vessels, mixing circulating fluid (blood) with interstitial fluid (hemolymph).
• Tubular hearts are muscular tubes that pump hemolymph through channels into chambers, draining back to a central cavity.
• Closed circulatory systems confine blood within vessels, separating it from interstitial fluid, found in complex invertebrates and vertebrates.
• Single circulation involves blood passing through the heart only once.
• Pulmocutaneous circulation is where gas exchange occurs in both lungs and skin.
• Incomplete circulation requires the blood to be pumped twice.
• Double circulatory systems are present in mammals.

Mammalian Circulatory System

• The cardiovascular system is a closed system with a four-chambered heart and blood vessels, including the lymphatic system.
• Transportation moves respiratory gases (oxygen and carbon dioxide), nutritive molecules (nutrients), and excretory wastes.
• Regulation transports hormones and assists in heat regulation.
• Protection includes blood clotting and immune defense.
• Homeostasis maintains bodily equilibrium.

Human Heart

• The muscular organ positioned behind the rib cage between the lungs, pumping blood throughout the body.
• The septum divides the heart, preventing blood flow between atria and ventricles.
• The tricuspid, or atrioventricular, valve allows oxygen-poor blood to flow to the right ventricle, preventing backflow.
• The bicuspid, or mitral, valve receives oxygen-rich blood from the left atrium, directing it to the left ventricle and then the aorta.
• The aorta is the body's major artery, carrying oxygen-rich blood to organs and muscles, called double circulation.

The Blood

• Blood consists of plasma (fluid) and blood cells (WBCs, RBCs, and platelets).
• Red blood cells (erythrocytes) make up 49% and transport oxygen and some carbon dioxide.
• White blood cells (leukocytes) are colorless, lack hemoglobin, are larger but fewer in number than RBCs and are irregularly shaped containing a nucleus.
• Neutrophils, eosinophils (target pathogens) and basophils (target parasites).
• Platelets (thrombocytes) stop bleeding and are cytoplasm fragments from megakaryocytes.
• Fibrin forms long, sticky strands to aid in clotting.

Blood Vessels

• Arteries carry blood away from the heart; smaller arteries are arterioles.
• Capillaries are narrow, thin-walled tubes where exchange occurs.
• Venules collect blood from capillaries.
• Veins return blood towards the heart.
• Valves prevent backflow in veins.
• Pulmonary circulation moves blood from the heart to the lungs and back.
• Systemic circulation moves blood from the heart to the rest of the body.
• Blood flow = Right Ventricle to Capillaries/Alveoli to Pulmonary Vein to Left Atrium to Left Ventricle to Aorta to Organs/Tissues to Superior Vena Cava to Right Atrium to Right Ventricle.
• The superior vena cava carries deoxygenated blood from the top of the body, while the inferior vena cava carries it from the bottom.
• The right atrium receives deoxygenated blood, and the left atrium receives oxygenated blood.
• The aorta is the largest blood vessel.

Plant Transport System

• Marcello Malphagi discovered sweet fluid after removing bark, revealing the plant transport system.
• Vascular tissues transport water (xylem) and nutrients (phloem).
• Tracheids are xylem cells in all vascular plants; flowering plants also have vessels.
• Angiosperms are flowery/fruit-bearing, while gymnosperms are nonflowering.
• Root pressure involves cells pumping water/ions into xylem, creating guttation (upward pressure).
• Capillary action is a substance's ability to draw another into it, causing water to rise.
• Cohesion-tension is when water molecules’ attraction pulls water upward from below.
• Transpiration pull or cohesion-tension explains water movement in tall plants.
• Phloem tissue conducts manufactured food (glucose and amino acids) via translocation.
• Herbaceous plant stems contain vascular bundles of xylem and phloem.
• Heartwood is wood in the center of matured trunks.
• Sapwood lies outside the heartwood.
• Monocots have one cotyledon and are not separated, while dicots have two and are separated.
• Mass-flow theory involves osmosis and dynamic pressure in material movement.

Immune System

• The immune system consists of cells, proteins, tissues, and organs protecting the body from foreign dangers.
• The immune response is the collective process by which the body distinguishes its own cells and tissues

First Line of Defense

• The innate immune system defends the body against pathogens nonspecifically.
• Involves physical and chemical barriers like skin, mucus, and saliva.
• Lysozyme is in saliva, tears, and nasal secretions.
• Mucus acts as a barrier, blocking bacteria from epithelial cells.
• Infection occurs when a pathogenic organism successfully invades the body.

Second Line of Defense

• The lymphatic system regulates the immune system, with vessels, organs, nodes, and lymph nodes that store cells for immune response.
• Macrophages are irregular WBCs that patrol and ingest microorganisms via phagocytosis, engulfing viruses, dust, and debris.
• Neutrophils are abundant WBCs that engulf bacteria via phagocytosis, releasing disinfecting chemicals.
• Natural killer cells act on virus-infected cells, killing them by puncturing the plasma membrane (with perforins).
• Dendritic cells are phagocytes that process and alert the adaptive immune system (lymphocytes) to antigens.
• Eosinophils target parasitic worms.
• Basophils contain histamines, causing inflammation during immune responses and allergic reactions.
• Mast cells also contain histamine, anchoring in response to injury/allergy.
• Lymphocytes are responsible for specific immunity.
• Antigens trigger an immune response.
• Cytokines are signaling proteins secreted when macrophages bind to an antigen.
• Histamines and prostaglandins are chemical signals released by infected/damaged cells.
• Interleukin-1, a regulatory protein produced by macrophages, is transported to the brain.

Third Line of Defense / Adaptive Immune Response

• Lymphocytes include T cells and B cells.
• B lymphocytes (B cells) mature in bone marrow.
• T lymphocytes (T cells) mature in the thymus gland.
• Activated T cells aid cellular immunity or cell-mediated immune response.
• Activated B cells direct antibody immunity/humoral immune response.

Humoral Immune Response

• Helper T cells are special T cells presented with an antigen.
• B cells divide rapidly, differentiating into plasma and memory cells upon encountering an antigen.
• Antibodies, produced by daughter plasma cells, are specialized proteins circulating in blood plasma and lymph.
• Neutralization prevents viruses or toxic proteins from binding to their target.
• Opsonization involves pathogens tagged by antibodies being consumed by macrophages/neutrophils.
• Complement activation occurs when antibodies attached to a pathogen's surface activate the complement system.
• IgA (Immunoglobulin Alpha) are found in mucosal areas (gut, respiratory tract) preventing colonization (in saliva, tears, breast milk).
• IgD (Immunoglobulin Delta) functions as an antigen receptor on B cells and may activate basophils/mast cells.
• IgE (Immunoglobulin Epsilon) binds to allergens, triggering histamine release from mast cells/basophils and protects against parasitic worms.
• IgG (Immunoglobulin Gamma) provides antibody-based immunity against pathogens (in blood).
• IgM (Immunoglobulin Mu) ia expressed on B cells (monomer) and in secreted form (pentamer).

Cell Mediated Immune Response

• Cytotoxic T cells, presented with a processed antigen by helper T cells, destroy infected cells and stops the spread of cancer and hepatitis B.
• Cytokines attract immune cells to the area.
• Immunity is resistance to illness.