Week 8: Cardiovascular Evolution

Pumps

The heart acts as a dual-chambered, muscular, and autonomic pump, essential for propelling blood through the cardiovascular system. The right side (right atrium and ventricle) moves deoxygenated blood to the lungs, while the left side (left atrium and ventricle) pumps oxygenated blood throughout the body. Valves, such as the tricuspid, pulmonary, mitral, and aortic valves, ensure one-way blood flow. Key components include: Cardiac Muscle, Heart chambers, Blood vessels

Ventilation Pumps

the mechanical, muscular, or anatomical mechanisms that drive the movement of air or water over respiratory surfaces (such as lungs or gills) to facilitate gas exchange. These systems create pressure gradients—moving from high to low pressure—to ensure a continuous supply of oxygen and removal of carbon dioxide

Circulation Pumps

muscular organs—primarily the heart—that propel blood or hemolymph through vessels to deliver oxygen/nutrients and remove waste. They drive the cardiovascular system, with human hearts functioning as dual pumps (right/pulmonary, left/systemic) that maintain pressure, enabling a continuous, one-way, high-pressure flow.

Diffusion

is the passive movement of molecules (like O₂,CO₂ , or nutrients) from an area of higher concentration to lower concentration, driven by random molecular motion (Brownian motion). It requires no energy, allows substances to pass through cell membranes, and continues until equilibrium is reached

Bulk Transport

an energy-intensive active transport mechanism (using ATP) that moves large molecules, particles, or vast quantities of smaller molecules across cellular membranes via membrane-bound vesicles. It bypasses the limitation of transport proteins for materials too big to pass through the lipid bilayer, primarily using endocytosis (importing) and exocytosis (exporting)

Fluid, pumps, vessels (relationship)

fundamental hydraulic system where a pump generates pressure to move a fluid through a network of vessels (pipes/tubes). This system relies on pressure gradients, where fluid flows from areas of high pressure to low pressure. In biological systems, this is represented by the cardiovascular system (heart, blood, blood vessels), while in engineering, it represents hydraulic circuits

• Pumps (Energy Source): These create the necessary pressure (hydrostatic pressure) to drive fluid flow. In humans, the heart acts as a dual-pump, where the left ventricle drives blood through systemic circulation and the right drives it through pulmonary circulation.

• Vessels (Conduits): These are the pipes through which the fluid travels. Arteries carry high-pressure fluid away from the pump, while veins return lower-pressure fluid to the pump.

• Fluid (Medium): The substance being transported, which in biological systems is blood (carrying oxygen/nutrients) or lymph.

Open circulation

a, typically low-pressure, system found in most invertebrates (e.g., insects, crustaceans, mollusks) where circulating fluid (hemolymph) is not entirely confined to vessels. The heart pumps hemolymph into open body cavities called hemocoels to directly bathe tissues and organs, allowing nutrient exchange before returning to the heart

Closed circulation

a, cardiovascular network where blood is entirely confined within vessels (arteries, veins, capillaries) and never fills body cavities, efficiently transporting nutrients and gases under high pressure. It is found in vertebrates, including humans and mammals, and some invertebrates like earthworms.

Hematocrit

easures the percentage of red blood cells in your blood, with normal ranges typically 42%–52% for men and 37%–47% for women. High levels indicate polycythemia or dehydration, causing headache or dizziness. Low levels indicate anemia, stemming from blood loss, iron deficiency, or chronic illness, causing fatigue or pale skin

Hemoglobin

an iron-rich protein in red blood cells that transports oxygen from the lungs to tissues and brings carbon dioxide back to the lungs. Normal levels are generally for men and for women. Low levels (anemia) cause fatigue, dizziness, and shortness of breath, while high levels can cause thick, sluggish blood, headaches, and dizziness

Hemocyanin

a copper-based, blue-pigmented protein that transports oxygen in the hemolymph (blood) of many invertebrates, including mollusks (snails, octopuses) and arthropods (crustaceans, spiders). Unlike iron-based hemoglobin, hemocyanin binds oxygen using two copper atoms, turning blue when oxygenated. Beyond respiration, it supports immune defense and, as keyhole limpet hemocyanin (KLH), is used in immunology as a vaccine carrier

Extrinsic muscle pumps

the rhythmic contraction of muscles surrounding veins and lymph vessels that aid in returning blood and lymph toward the heart, crucial for circulation during exercise. These pumps prevent pooling by utilizing external compression to increase venous return.

hearts

a four-chambered, fist-sized muscular organ located in the mediastinum (center of the chest), responsible for pumping blood throughout the body via the cardiovascular system. It separates oxygen-poor blood (right side) from oxygen-rich blood (left side) using chambers, valves, and electrical impulses to ensure one-way circulation

Peristalsis

an involuntary, wave-like muscle contraction that moves food, liquids, and waste through the digestive tract, starting in the esophagus and ending at the rectum. Triggered by food stretching the gut walls, it also occurs in the bile duct and ureters. Problems cause issues like constipation or diarrhea.

single circulation

a, low-pressure circulatory system found in fish and some, other aquatic animals where blood passes through the heart only once per complete circuit of the body. Blood travels from the two-chambered heart to the gills for oxygenation, flows directly to the body tissues, and returns to the heart

Double circulation

a highly efficient, two-loop circulatory system found in mammals, birds, and reptiles where blood passes through the heart twice per complete circuit. It features separate pulmonary (heart-lung-heart) and systemic (heart-body-heart) circuits, ensuring complete separation of oxygenated and deoxygenated blood to maintain high metabolic rates

Divided Circulation

a system in mammals and birds where blood passes through the heart twice, separating oxygenated and deoxygenated blood into two distinct circuits: the pulmonary circuit (heart to lungs) and the systemic circuit (heart to body). This mechanism allows for higher, more efficient blood pressure and oxygen delivery

Pulmonary Circulation

the low-pressure, low-resistance pathway carrying deoxygenated blood from the right ventricle to the lungs for gas exchange and returning oxygenated blood to the left atrium. It facilitates oxygen absorption and carbon dioxide removal in the alveolar capillaries, critical for systemic oxygenation

Systemic circulation

the high-pressure, main circuit of the cardiovascular system that pumps oxygenated blood from the left ventricle through the aorta to the body's tissues, supplying nutrients and oxygen while removing waste. It returns deoxygenated blood to the right atrium via veins, crucial for homeostasis

perfusion

the essential delivery of oxygenated blood to body tissues via the cardiovascular system, crucial for organ function. A _____ is a specialized healthcare professional who operates heart-lung machines to maintain blood circulation during open-heart surgery. Poor _____ signs include fatigue, cyanosis, cold skin, or organ dysfunction, treated by improving blood flow via hydration, medications, or surgical interventions

Elastic storage

illustrates the reversible, linear, or non-linear relationship where a material stores mechanical energy without permanent deformation, following Hooke's Law () within its elastic limit. The slope represents Young's modulus (stiffness), and energy is stored as the area under this curve

Sinus venosus

a rare congenital heart anomaly where a defect near the superior or inferior vena cava causes a left-to-right shunt, often accompanied by anomalous pulmonary venous return. Symptoms include fatigue, palpitations, and shortness of breath due to right-sided heart overloading. It is primarily diagnosed via echocardiography and treated with surgical repair, usually in childhood, to prevent pulmonary hypertension

atrium

the two thin-walled upper chambers of the heart that act as receiving reservoirs for blood entering from the circulatory system. The right atrium receives deoxygenated blood from the body, while the left atrium receives oxygenated blood from the lungs. During the cardiac cycle, they contract to fill the ventricles

ventricle

the two lower, thick-walled pumping chambers of the heart (left and right) that receive blood from the atria and propel it to the lungs and body. The left ventricle pumps oxygenated blood to the body via the aorta, while the right ventricle pumps deoxygenated blood to the lungs. They are separated by the septum and are crucial for circulation

conus arteriosus

the smooth-walled, muscular outflow tract of the right ventricle leading to the pulmonary artery, crucial for transporting deoxygenated blood. It serves as a, conical, contractile, support structure for the pulmonary valve and is involved in regulating blood flow, with developmental significance in separating blood flow, especially in non-mammalian vertebrates

partial septa in atrium (lungfish)

unique, partially separated heart representing a transitional step towards tetrapods, featuring a partial atrial septum (interatrial septum) that divides the single atrium into larger right and smaller left chambers. This partial partition helps keep oxygenated blood from the lungs separate from deoxygenated systemic blood

ventricle (lungfish)

a saccular, entirely trabeculated chamber featuring an incomplete ventricular septum that partially divides it into left and right sides. This specialized, Type I heart structure enables partial separation of oxygenated and deoxygenated blood, reflecting the lungfish's evolutionary position as a link between fish and tetrapods

Valved conus arteriosus (lungfish)

a muscular conus arteriosus containing a spiral valve that helps separate oxygenated blood (from the lungs) and deoxygenated blood (from the body). This structure is part of an evolved, partially divided heart, allowing them to manage blood flow to specific gill arches or pulmonary arteries

Pulmonary artery (lungfish)

arises from the last (posterior) pair of efferent branchial arches (arteries), crucial for directing deoxygenated blood to the lungs for gas exchange. During air-breathing, 20–70% of total cardiac output shunts to the pulmonary circulation. This vascular system allows, particularly in African and South American species, for efficient oxygen uptake, and the pulmonary artery is under vagal/cholinergic control.

pulmonary vein (lungfish)

carries oxygenated blood from the lungs directly to the heart, specifically entering the sinus venosus or directly into the left side of the atrium. It plays a crucial role in separating oxygenated pulmonary blood from deoxygenated systemic blood, facilitating efficient respiration in air-breathing fish

Lung (lungfish)

ancient, air-breathing lobe-finned fish that possess both gills and one or two primitive lungs modified from their swim bladder. These, "living fossils" can breathe air to survive in low-oxygen, drying, or stagnant water by, in some species, forming a protective mud-and-mucus cocoon.

ductus arteriosus (lungfish)

a paired, muscular vessel connecting the pulmonary arteries to the dorsal aorta, serving as a critical, permanent shunt that aids in oxygenating blood during air breathing. Unlike tetrapods, this structure does not close at birth or metamorphosis but remains functional in adults to manage bimodal respiration

septum in atrium, ventricle (Mammal)

The interatrial septum divides the atria (often with a remnant hole, the fossa ovalis), while the interventricular septum separates the ventricles with a thick muscular lower part and a thinner membranous upper part