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Circulatory System
| Question | Answer |
|---|---|
| How many chambers does the human heart have? | 4 — 2 atria and 2 ventricles |
| How many heart chambers do most reptiles have? What about crocodiles and alligators? | Most reptiles have 3 chambers; crocodiles and alligators have 4. |
| What are the two atrioventricular valves and what do they connect? | Tricuspid — connects right atrium to right ventricle. Bicuspid/Mitral — connects left atrium to left ventricle. |
| What are the two semilunar valves and what do they connect? | Pulmonary — connects right ventricle to pulmonary artery. Aortic — connects left ventricle to aorta. |
| What is systole? | Contraction of the atria/ventricles. |
| What is diastole? | Relaxation of the atria/ventricles. |
| What system regulates the cardiac cycle? | The autonomic nervous system. |
| What is the sinoatrial (SA) node and what does it do? | The pacemaker node located in the upper right atrium. It initiates contraction of the atria and stimulates the atrioventricular (AV) node. |
| What is the atrioventricular (AV) node? | A node stimulated by the SA node that passes the electrical impulse to the Bundle of His between the ventricles. |
| What is the Bundle of His? | A structure between the ventricles that passes the electrical signal from the AV node to the Purkinje fibers. |
| What are Purkinje fibers? | Fibers that receive the signal from the Bundle of His and trigger contraction of both ventricles. |
| What is the correct order of the cardiac conduction pathway? | SA node → AV node → Bundle of His → Purkinje fibers → ventricular contraction |
| What is the pulmonary circuit? | Heart (right) → Lungs → Heart (left). Carries deoxygenated blood to the lungs and returns oxygenated blood to the heart. |
| Which vessel has the lowest oxygen concentration in the body? | The pulmonary artery. |
| Which vessel has the highest oxygen concentration in the body? | The pulmonary vein. |
| What is the systemic circuit? | Heart (left) → Body → Heart (right). Delivers oxygenated blood to body tissues and returns deoxygenated blood to the heart. |
| Trace blood flow through the pulmonary circuit. | Deoxygenated blood: right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary artery → lungs (oxygenated) → pulmonary vein → left atrium |
| Trace blood flow through the systemic circuit. | Oxygenated blood: left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → arteries → arterioles → capillaries → tissues → venules → veins → vena cava → right atrium |
| What are arteries and what is their exception? | Arteries carry oxygenated blood away from the heart. Exception: the pulmonary artery carries deoxygenated blood to the lungs. |
| What are arterioles? | Small branches of arteries wrapped in smooth muscle; they are major determinants of blood pressure. |
| What are veins and what is their exception? | Veins carry deoxygenated blood toward the heart. Exception: the pulmonary vein carries oxygenated blood from the lungs to the heart. |
| What are venules? | Small vessels that collect blood and channel it back into veins. |
| What are capillaries? | The smallest blood vessels, consisting of a single layer of endothelial cells. They allow exchange of gas, nutrients, and waste with body tissues. |
| What are precapillary sphincters? | Structures that regulate blood flow into capillaries. A relaxed sphincter increases flow and nutrient delivery; a tighter sphincter reduces flow. |
| What is plasma? | An aqueous mix of blood proteins, salts, gases, and nutrients. |
| What is serum? | Plasma without clotting proteins. |
| What are platelets? | Cell fragments responsible for blood clotting. |
| What are erythrocytes (RBC)? | Red blood cells that transport oxygen on hemoglobin. |
| What are leukocytes (WBC)? | White blood cells; phagocytes that engulf foreign particles. |
| How are blood types (A, B, O) determined? | By the presence of specific antigens on the erythrocyte membrane. |
| What antibodies does each blood type produce? | Type A produces anti-B antibodies. Type B produces anti-A antibodies. Type AB produces neither. Type O produces both anti-A and anti-B antibodies. |
| What is agglutination? | When antibodies attack blood cells carrying foreign antigens, causing them to clump together. Occurs when mismatched blood types are given. |
| Why is blood type AB+ the universal recipient? | Because AB+ individuals do not produce antibodies against any blood type, so they can receive any blood without triggering an immune response. |
| Why is blood type O- the universal donor? | Because O- blood has no antigens to trigger an immune response in the recipient. |
| What is the Rhesus (Rh) factor? | Another blood surface antigen, classified as positive (+) or negative (−), that further determines blood type compatibility. |
| What has the lowest oxygen levels in the entire body? | Pulmonary arteries |
| What has the highest oxygen levels in the entire body? | Pulmonary veins |
| Superior and inferior vena cava | The two largest veins in the body, carrying deoxygenated blood from the upper and lower parts of the body, respectively, back to the right atrium of the heart. (Systemic circulation) |
| Mitral Valve | heart valve located between the left atrium and left ventricle that ensures blood flows in one direction and prevents backflow when the ventricle contracts (systemic circulation) |
| Tricuspid Valve | heart valve located between the right atrium and right ventricle that allows blood to flow from the atrium to the ventricle and prevents it from flowing backward when the ventricle contracts (systemic circulation) |
| Aortic Valve | valve located between the left ventricle and the aorta that opens to allow oxygen-rich blood to leave the heart and flow into the body, and closes to prevent blood from flowing back into the left ventricle (systemic circulation) |
| Electrical transmission: | Cardiac cells are separated by intercalated disks (cell-to-cell junctions), which contain gap junctions (permit ion flow between cells), allowing electrical signals to spread to adjacent cells and ensuring coordinated cell contraction. |
| Cardiac Output (CO) = | Stroke Volume (SV) * Heart Rate (HR) |
| CO | volume of blood pushed out of the ventricles/minute. |
| SV | volume of blood discharged from the ventricles/contraction. |
| HR | number of heart contractions/minute |
| Stroke Volume = | End Diastolic Volume (EDV) - End Systolic Volume (ESV) |
| EDV | volume of blood in the ventricles before contraction (completely filled). |
| ESV | volume of blood left in the ventricles following contraction (residual amount). |
| Blood Pressure (BP) = | Cardiac Output * Systemic Vascular Resistance (SVR) |
| BP: | pressure of circulating blood against the vessels. |
| SVR: | resistance to blood flow. Influenced by vessel diameter (narrow = high resistance) and blood viscosity (thicker blood = higher resistance). |
| Layers of artery wall (superficial to deep): | connective tissue, smooth muscle, elastic layer, endothelium |
| Hydrostatic pressure: | fluid inside of capillaries pushes up against vessel walls, causing fluid to exit (filtration: water, oxygen, and nutrients are pushed out of vessels, into cells). |
| Oncotic pressure: | blood protein concentration pulls fluid into the capillaries (reabsorption: extra fluid, waste products and CO2 re-enter capillaries). |
| Placenta: | interface between fetal and maternal blood supply; site of gas and waste exchange. |
| Ductus venosus: | blood vessel which bypasses the (nonfunctional) liver, allowing circulation to go straight from the umbilical vein to the inferior vena cava. |
| Foramen ovale: | hole between the two atria which allows blood to flow from right atrium into the left atrium, bypassing the (nonfunctional) lungs. |
| Ductus Arteriosus: | vessel that connects the pulmonary artery to the aorta; allows blood to bypass the lungs and heart. |
| Blood Brain Barrier (BBB): | highly selective, semi-permeable membrane separating brain cells from the blood to prevent harmful substances from entering brain tissue. Allows helpful molecules to pass (e.g., O2, CO2, small lipid-soluble molecules). |
| Tight junctions: | produce a watertight seal to prevent most substances from crossing the BBB. |
| Astrocytes: | nervous system support cells that wrap around blood vessels, supporting the BBB. |
| Myoglobin: | a protein in muscles that binds and stores O2 for use when availability is low. |
| Hemoglobin | protein which carries (binds and releases) O2; found in RBCs. Contains 4 heme groups (each with an Fe2+ atom) that exhibit cooperative binding |
Created by:
smurtab