Circulatory System PDF

8/27/24, 6:14 PM Platform | Study Fetch Types of Circulatory Systems (00:16 - 01:30) No Circulatory System Simplest organisms use simple diffusion to exchange gas and nutrients with their environment Includes prokaryote...

8/27/24, 6:14 PM Platform | Study Fetch Types of Circulatory Systems (00:16 - 01:30) No Circulatory System Simplest organisms use simple diffusion to exchange gas and nutrients with their environment Includes prokaryotes (archaea, bacteria) and some eukaryotes (protists, fungi, some invertebrates) Simple diffusion is sufficient for their needs Open Circulatory System Blood/hemolymph flows through open sinuses around organs and tissues No capillary beds, just open pockets that bathe the tissues Increases diffusion and exchange with the environment Found in invertebrates like molluscs, arthropods, and echinoderms Closed Circulatory System Blood flows through a closed system of blood vessels Found in both invertebrates and vertebrates Invertebrate systems are more simple, with a heart pumping blood through a basic capillary bed Vertebrate systems are more complex, with a 4-chambered heart and more intricate capillary networks The Human Heart (06:15 - 06:59) Anatomy and Physiology Pulmonary circulation: Deoxygenated blood flows into the heart through the superior and inferior vena cava Enters the right ventricle and is pumped to the lungs Oxygenated in the lung capillaries Systemic circulation: Oxygenated blood returns from the lungs to the heart Flows out of the heart through the aorta to deliver oxygen to tissues Deoxygenated blood returns to the heart through the vena cavae Blood Vessels and Blood Types (00:48 - 01:03) Blood Vessels Will be covered in more detail later in the lesson https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 1/7 8/27/24, 6:14 PM Platform | Study Fetch Blood Types Will also be covered in more detail later in the lesson Key Takeaways (00:00 - 06:59) Circulatory systems range from simple diffusion to complex closed systems The human heart has a 4-chambered structure that powers the pulmonary and systemic circulatory systems Blood vessels and blood types are important components of the circulatory system that will be explored further Blood Flow and the Cardiovascular System (00:07:14 - 00:13:56) Blood Flow from the Body to the Heart (00:07:14 - 00:08:25) Blood flows from the upper body and brain into the heart through the superior vena cava Blood from the lower body, lungs, digestive system, and internal organs flows into the inferior vena cava and up to the heart The blood enters the right atrium of the heart The blood then flows through the right AV (tricuspid) valve into the right ventricle Blood Flow from the Heart to the Lungs (00:08:25 - 00:08:54) The blood is ejected from the right ventricle through the pulmonary semilunar valve into the pulmonary arteries The blood in the pulmonary arteries is deoxygenated Arteries and veins denote the direction of blood flow, not the oxygenation status Blood Flow from the Lungs to the Heart (00:08:54 - 00:10:35) The oxygenated blood returns from the lungs through the pulmonary veins to the left atrium The blood then flows through the left AV (mitral or bicuspid) valve into the left ventricle Blood Flow from the Heart to the Body (00:10:35 - 00:13:33) The blood is ejected from the left ventricle through the aortic semilunar valve into the aorta https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 2/7 8/27/24, 6:14 PM Platform | Study Fetch The aorta is the largest artery in the body and distributes the oxygenated blood to the tissues Summary of the full blood flow: Blood returns to the heart through the vena cavae Flows through the right side of the heart to the lungs Returns oxygenated to the left side of the heart Pumped out through the aorta to the body Importance of Understanding Blood Flow (00:13:33 - 00:13:56) Understanding the schematic of blood flow is crucial for understanding human physiology It allows you to think about how changes in blood flow can affect the heart and blood pressure The Layers of the Heart (00:13:56 - 00:14:08) In cardiology, I have experience in these areas We will go over the different layers of the heart (00:14:08 - 00:14:21) The endocardium is the innermost layer of the heart, in direct contact with the blood The myocardium is the inner muscular layer that provides the force and squeezing energy to push blood out The myocardium is separated from the blood by the endocardium (00:14:21 - 00:14:31) The pericardium is a membranous layer that lays on the myocardium The pericardium creates a mainly frictionless layer that allows the heart to slide (00:14:31 - 00:14:48) The pericardium has two layers: The parietal pericardium The visceral pericardium These two layers slide over each other with a space in between (00:14:48 - 00:15:03) If there is a buildup of fluid in the space between the pericardial layers, it is called a pericardial effusion This space should stay very narrow to allow the heart to rock back and forth during expansion and contraction (00:15:03 - 00:15:15) The frictionless environment of the pericardial space is important to prevent problems The endocardium is in direct contact with the blood (00:15:15 - 00:15:40) If blood flow to the heart muscle is cut off, typically the endocardium does not die The deeper layers of the myocardium, furthest from the blood supply, are most prone to dying in the event of ischemia or a blood clot This is where damage often occurs during heart attacks or angina https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 3/7 8/27/24, 6:14 PM Platform | Study Fetch The Electrical Conduction System of the Heart (00:15:55 - 00:16:25) Understanding the electrical conduction system is important to know how the heart beats and coordinates its contractions Key components: SA node: The heart's main pacemaker AV node: Has a built-in delay timer to coordinate atrial and ventricular contractions (00:16:25 - 00:17:14) The SA node fires, sending signals to the AV node The AV node delays the signal to allow the atria to fully empty into the ventricles before the ventricles contract This ensures the ventricles are filled when they contract (00:17:14 - 00:18:22) The signal then travels down the bundle of His and the Purkinje fibers to stimulate the ventricular myocardium This allows the ventricles to contract and pump blood out to the body and lungs (00:18:22 - 00:18:34) Summary of electrical conduction: SA node -> AV node -> bundle of His -> Purkinje fibers -> ventricular myocardium Systole vs. Diastole (00:18:34 - 00:19:18) Systole is the contraction phase of the heart, when the ventricles are firing and exerting maximum pressure Diastole is the filling phase, when the atria are pushing blood into the ventricles (00:19:18 - 00:20:04) During systole, the semilunar valves are open and blood is forced into the aorta and pulmonary arteries During diastole, the semilunar valves are closed and the ventricles are filling (00:20:04 - 00:20:26) Blood pressure readings reflect these two phases: Systolic pressure: Peak pressure during ventricular contraction Diastolic pressure: Minimum pressure during ventricular filling (00:20:26 - 00:20:50) Mnemonic to remember: Systole = when ventricles fire Diastole = when ventricles fill https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 4/7 8/27/24, 6:14 PM Platform | Study Fetch The Cardiac Cycle and EKG Interpretation (00:20:50 - 00:22:30) The Cardiac Cycle Diastole is the filling phase of the heart, where the atria contract to fill the ventricles. Systole is the contraction phase of the heart, where the ventricles contract and pump blood out of the heart. The heart sounds "Boop Boop, boop, boop loop" are caused by the snapping of the heart valves: The "love" sound is when the ventricles contract and the semilunar valves open as the AV valves close. The "dub" sound is when the atria contract and the AV valves open as the heart is filling with blood. EKG Interpretation EKGs are very common tests used to assess heart function. The different waves and spikes on an EKG represent the electrical activity of the heart: The P wave represents the firing of the atria. The QRS complex represents the firing of the ventricles. The T wave represents the repolarization of the ventricles. The pause between the P wave and QRS complex is due to the AV node delaying the electrical signal to allow the atria to fill the ventricles. Fetal Circulation (00:24:52 - 00:26:50) Differences in Fetal Circulation Fetal circulation is different from adult circulation due to the fetus being bathed in amniotic fluid and not needing to use its lungs. There are two important shunts in fetal circulation: 1. Ductus Arteriosus: Connects the pulmonary artery to the aorta, bypassing the lungs. 2. Ductus Venosus: Bypasses the fetal liver, allowing the fetus to take advantage of the mother's liver function. These shunts allow the fetus to get oxygenated blood from the mother without using its own lungs or liver. Blood Vessels (00:27:02 - 00:27:47) Structure of Blood Vessels Blood vessels have three main layers: 1. Endothelial layer 2. Smooth muscle layer 3. Connective tissue layer Arteries tend to have a thicker, more muscular wall compared to veins due to the higher pressures they experience. https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 5/7 8/27/24, 6:14 PM Platform | Study Fetch The Circulatory System The Importance of Arterial Structure (00:27:47 - 00:28:02) Blood is pumped directly out of the heart into the arteries Arteries need a lot of connective tissue and muscle to contain the high pressure of blood flow Without this structural support, the arteries could fail or give out Differences Between Arteries and Veins (00:28:02 - 00:28:21) Veins have a much less intense structure surrounding them Veins have a thinner smooth muscle layer and less connective tissue Veins do not have the same strength as arteries The Portal Venous System (00:28:21 - 00:29:16) Normally, blood flows from the heart to an artery, through a capillary bed, into the venous circulation, and back to the heart But in some places, blood flows through multiple capillary beds before returning to the venous circulation The main example is the liver: Blood flows from the GI tract into the portal vein It then flows through the liver before returning to the vena cava and heart Blood Clotting (00:29:42 - 00:30:31) Blood clotting is essential for survival, as it plugs any leaks in blood vessels Clotting factors lead to the activation of prothrombin into thrombin Thrombin then causes fibrinogen to be cleaved into fibrin, forming a mesh that creates a clot Blood Composition (00:30:42 - 00:31:23) Blood is composed of: Plasma (55%) Buffy coat (white blood cells) Erythrocytes (red blood cells, 45%) The erythrocyte/red blood cell percentage is called the hematocrit Hematocrit can vary between men, women, and age groups https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 6/7 8/27/24, 6:14 PM Platform | Study Fetch Blood Types (00:31:23 - 00:33:25) There are four main blood group antigens: A, B, AB, and O People with type A make anti-B antibodies, and vice versa Type AB can receive any blood type (universal recipient) Type O has no antigens and can donate to any type (universal donor) Conclusion (00:33:38 - 00:34:20) The circulatory system is a complex but fascinating system It is highly relevant clinically, with many potential issues and diseases If you have any further questions, feel free to ask in the chat box https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce2cedf069b6d6b89c5eb8/document?go=note 7/7